fim EARTH
SCI ENC E‘?

 

Structural Geology
of the Confusion Range,
West-Central Utah

 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 971

 

JAN 25 1977

{yr-54".}? $3
‘1' ‘ 7/» 5.1%;

 

Structural Geology
of the Confusion Range,
West-Central Utah

By Richard K. Hose

 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 971

 

 

 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1977

UNITED STATES DEPARTMENT OF THE INTERIOR

THOMAS S. KLEPPE. Sl‘fl’l‘ltln‘

GEOLOGICAL SURVEY

V. E. McKelvey, Din'dm

Library of Congress Cataloging in Publication Data

Hose, Richard Kenneth, 1920-
Structural geology of the Confusion Range, west-central Utah.

(Geological Survey Professional Paper 971)

Bibliography: p. 9.

Supt. of Docs. no.: I 19.162971

1. Geology—Utah—Confusion Range. 1. Title. II. Series: United States Geological Survey Professional Paper 971.
QE170.C59H67 551.8’09792’45 76-608301

 

For sale by the Superintendent of Documents, Us, Government Printing Office
Washington, DC. 20402
Stock Number 024-001—02923—5

CONTENTS

Page
Abstract ______________________________________________________________________________ 1
Introduction __________________________________________________________________________ 1
Structural history ______________________________________________________________________ 1
Late Mesozoic to early Cenozoic orogeny ________________________________________________ 3
Structures within the structural trough ________________________________________________ 3
Low-angle faults __________________________________________________________________ 3
Evidence for the higher décollement ________________________________________________ 4
Evidence for the lower décollement __________________________________________________ 6
Structures of the upper plate __________________________________________________________ 6
Structure of the intermediate plate ______________________________________________________ 6
Other structures ______________________________________________________________________ 7
Conger Range fault ________________________________________________________________ 7
Salt Marsh Range fault ____________________________________________________________ 7
Basin and Range orogeny __________________________________________________________ 7
Summary and conclusions ______________________________________________________________ 8
References cited ______________________________________________________________________ 9
ILLUSTRATIONS
Page
PLATE 1. Generalized geologic map of a part of the Confusion Range, west-central Utah ____________________________ In pocket
FIGURE 1. Index map of east-central Nevada and west-central Utah showing location of mountain ranges and position of
Butte and Confusion Range structural troughs ___________________________________________________________ 2
2. Generalized geologic map of northwest end of Plympton Ridge __________________________________________________ 5
3. Schematic cross sections showing stages of development of decollement and thrust faults and folds in axial part of
Confusion Range structural trough ______________________________________________________________________ 8

III

 

STRUCTURAL GEOLOGY OF THE CONFUSION RANGE,
WEST-CENTRAL UTAH

By RICHARD K. HOSE

ABSTRACT

More than 33,000 feet (10,000 metres) of generally conformable
upper Precambrian (present in the subsurface), Paleozoic, and Lower
Triassic strata, all overlain in profound unconformity by Oligocene
and younger volcanic and sedimentary rock, are present in the Con-
fusion Range of west-central Utah. During the late Mesozoic to early
Cenozoic, the pre-Tertiary rocks were deformed into a structural
trough or synclinorium concave in map view to the west. The de-
velopment of the trough generated two décollement-type faults,
above which rocks glided toward its axis. This gliding resulted in the
formation, in the highest plate, of isoclinal and recumbent folds, the
latter with their lobes directed into the axis. After the trough was
filled, additional steepening of the west flank caused the develop-
ment of a lower décollement that died out eastward toward the axis
of the trough. Movement of this décollement caused local overturn-
ing of the intermediate and upper plates and a more pronounced
westward concavity of the trough. Subsequent increase of the slope of
the flanks of the trough, whether by uplift or compression, achieved
relief of axial stress by thrusting away from the axis of the trough.

INTRODUCTION

The Confusion Range of west-central Utah (fig. 1) is
structurally different from ranges to the immediate
east and west in that it forms an elongate, curved
structural trough or synclinorium (Hose, 1966). The
House Range to the east is a block-faulted homoclinal
mountain range that dips gently to the east and is
made up mainly of Cambrian rocks. To the west, the
Snake Range contains intricately faulted allochthon-
ous rocks of Cambrian to Permian age that have moved
over a lower plate of Cambrian and older rocks. It has
been reasonably well established that the major low-
angle fault or fault complex of the Snake Range ex-
tends eastward beneath the Confusion Range (Misch,
1960; Hose and Danés, 1967, 1973). Although the
Paleozoic section in the Snake Range has been greatly
attenuated by low-angle faults that emplaced younger
rock or older, the section in the Confusion Range is
reasonably intact and is not greatly attenuated. This
paper describes the more important structural ele-
ments of the Confusion Range structural trough and
presents an explanation for their development.

STRUCTURAL HISTORY
The Confusion Range of west-central Utah (fig. 1; pl.

 

1) contains about 23,000 ft (7,000 m) of exposed Upper
Cambrian to Lower Triassic miogeosynclinal strata.
On the basis of outcrops in surrounding areas, it is
likely that an additional 6,000—8,000 ft (1,800—2,400
m) of Lower and Middle Cambrian strata, plus an inde-
terminate but great thickness of Precambrian rocks, is
present in the subsurface. There is some indirect evi-
dence that Middle and Upper Triassic and Jurassic
rocks were also deposited but were removed by post-
orogenic erosion. Rocks of this age (Triassic and J uras-
sic) are present at Blue Mountain in the southern Wah
Wah Range where they are overthrust by Cambrian
rocks (Miller, 1966). The Wah Wah Range and Confu-
sion Range are in general structurally continuous.

The region was affected by two major tectonic
events: the older one took place sometime between
Late Jurassic and Oligocene time, and the younger, the
Basin and Range orogeny, sometime after Oligocene
time. There is some uncertainty as to just when tec-
tonism took place within the older period and whether
it was a single or multiple event, representing
orogenesis perhaps in both the Cretaceous and the
early Tertiary.

Clearly the older event(s) occurred prior to 36.5 m.y.
(million years) ago, for gently dipping volcanic rocks of
this age (early Oligocene) rest on severely deformed
rocks of Permian age just north of the area covered by
plate 1.

In the Schell Creek Range of eastern Nevada, which
is about 40 mi (64 km) west of the Confusion Range,
Drewes (1967) reported clasts of Prospect Mountain
Quartzite, which was then considered Early Cambrian,
incorporated in what are believed to be equivalents of
the Eocene Sheep Pass Formation. Hose and Blake
(1976) suggested that unconformable relations at the
base of Sheep Pass equivalents elsewhere in eastern
Nevada, and the presence of Cambrian-derived mate-
rial, required significant physiographic and structural
relief prior to and during the deposition of the Sheep
Pass and its equivalents. Such tectonism was clearly
pre-Eocene, and if regionally operative, the episode(s)
would be limited to the latest Jurassic to Paleocene.

An additional indirect clue to the age of tectonism

1

STRUCTURAL GEOLOGY OF THE CONFUSION RANGE, UTAH

 

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FIGURE 1.——Index map of east-central Nevada and west-central Utah showing location of mountain ranges and position of Butte and

STRUCTURES WITHIN THE STRUCTURAL TROUGH 3

within the former miogeosyncline can be found to the
east in the para-autochthonous rocks just east of the
Sevier‘orogenic belt of central Utah. There, the con-
formable relatively fine grained Triassic and Jurassic
rocks are overlain by coarse-grained orogenic boulder
conglomerates of Cretaceous age. The amount of relief,
both structural and physiographic, indicated by the
coarse detritus is believed to define the climax of the
older structural events in eastern Nevada and western
Utah and thus dates the tectonism as Cretaceous. Ad—
mittedly, some or all of these assumptions may be un-
warranted, and conclusions on regional correlation and
genesis may likewise be unwarranted. Tectonism dur-
ing the early Tertiary (Laramide) is also known to
occur along the eastern part of the Cordillera and may
have affected western Utah. In view of the uncertain—
ties of dating, the older tectonism is referred to herein
as the late Mesozoic to early Cenozoic orogeny, and the
younger as the Basin and Range orogeny.

The younger event reached a climax in east-central
Nevada some time after 17 my. ago (middle Miocene)
and before early Pliocene (Hose and Blake, 1976).

LATE MESOZOIC TO
EARLY CENOZOIC OROGENY

At some time during the late Mesozoic to early
Cenozoic, the concordant Paleozoic and Triassic se-
quence of the Confusion Range was downwarped into a
structural trough or synclinorium more than 60 mi
(97 km) long and at least 8 mi (13 km) wide. More than
40 mi (64 km) of this trough lie within the mapped
area (fig. 1; pl. 1). From Cowboy Pass southward
through the Conger Range quadrangle and another 20
mi (32 km) beyond the map area, the trend of the
trough is N. 10°—15° E., whereas north of Plympton
Ridge in the Disappointment Hills the trend is about
N. 25° W. Instead of marking a smooth transition be-
tween these two trends, the segment between them
making up Plympton Ridge shows a sharp accentua-
tion to N. 45° E. at Cowboy Pass at the south end of the
segment, to north-south in the central part, to N. 50°
W. in the northern part of Plympton Ridge. The south-
ern part of the trough in the Needle Range is overlap-
ped by volcanic rocks, whereas the northwestward ex-
tension is truncated against a Basin-Range fault on
the east side of the Deep Creek Range (fig. 1). Its pre-
Basin and Range extent beyond this fault to the north
or northwest is unknown.

The east flank of the structural trough is fairly well
defined by dips of 10°—40° W. in the vicinity of Granite
Mountain, by west dips in the southern part of the
Cowboy Pass quadrangle, and by west dips at inter-
mediate latitudes in the buttes of White Valley (pl. 1).

 

The strikes or contact projections of Devonian units
beneath the alluvium of White Valley are mildly con-
cave westward and do not reflect the sharp westward
concavity of Plympton Ridge.

The west flank of the trough within the map area is

‘best shown by easterly dips of the pre-Permian

Paleozoic rocks in the Conger Range. To the south of
the map area, the pre-Permian Paleozoic of the west-
ern Burbank Hills also has pronounced easterly dips
(Hintze, 1963). A reconstructed cross section expresses
the west flank of the trough across the northern part of
the map area (Hose, 1975a). The variety of structures
along the axis of the trough are of particular signifi-
cance in that they provide the basis for a hypothesis on
their origin.

The original structural relief on the trough can be
approximated by removing the effects of the Basin and
Range orogeny. The top of the Precambrian Z and
Lower Cambrian Prospect Mountain Quartzite should
be at a depth of 20,000 ft (6,100 m) below sea level be-
neath Cowboy Pass along the axis of the trough, assum-
ing no significant repetition or elimination of strata
by faulting. To the east, the top of the Prospect Moun-
tain is present at an elevation of 6,000 ft (1,830 m) in
Marjum Pass in the House Range, but if the Basin and
Range flanking fault had dip slip of about 4,000 ft
(1,220 m), it should formerly have been at an elevation
of about 2,000 ft (610 m). This would provide about
4 mi (6.4 km) of structural relief between the House
Range and Cowboy Pass in 20 mi (32 km), indicating a
dip of about 11°.

To the west, the top of the Prospect Mountain is now
at an elevation of more than 8,000 ft (2,400 m) in the
northern Snake Range, and assuming it was elevated
along a Basin and Range fault with about a 2,000 ft
(610-m) displacement, its pre-Basin and Range eleva-
tion should have been at 6,000 ft (1,800 m) to give a
total relief of 26,000 ft (7,900 m) in 20 mi (32 km), or an
average slope of more than 15°. Present dips indicate
that the west flank was the steeper. It thus seems cer-
tain that rather high dips were attained on the flanks
of the trough as it developed.

If the Basin and Range orogeny significantly uplifted
the northern Confusion Range and accommodations
were made for a modest horstlike uplift, then the pre-
Basin and Range structural relief would be even great-
er than cited above.

STRUCTURES WITHIN THE
STRUCTURAL TROUGH

LOW-ANGLE FAULTS

Two principal types of low—angle faults characterize
the structural trough. The first and most important in

4 STRUCTURAL GEOLOGY OF THE CONFUSION RANGE, UTAH

terms of structural complexity is the décollement type
that emplaces younger rock on older, and the second is
the thrust fault that emplaces older rock over younger.
The thrust faults, which locally cut the décollements,
are of relatively small displacement and are rooted
(pl. 1, D—D’, E—E’, and G—G’).

The two décollements in the map area (pl. 1,D-D’ to
I—I’) formed within the stratigraphic zones of least
competence. The structurally higher of these two faults
has its sole in the upper part of the Arcturus Forma-
tion, usually close to beds of gypsum. In places, move-
ment on the uppermost décollement placed Arcturus
over Arcturus, but locally younger beds, such as the
Kaibab Limestone, Plympton Formation, or Gerster
Limestone (three units composing the Park City
Group), are in fault contact with the Arcturus. Gener-
ally the fault cuts the higher parts of the Arcturus, but
in places it cuts deeper into the Arcturus, as west of
Granite Mountain where Virturally the entire upper
part of the unit is faulted out. The outline of outcrop of
the Park City Group and the Thaynes Formation is
approximately coincident with the upper décollement,
and so these units are allochthonous everywhere in the
map area. This allochthon is referred to informally as
the upper plate.

The lower décollement cut out from 100 to 400 ft (30
to 122 m) of strata and emplaced highest Chainman
Shale and lower Ely Limestone over parts of the upper
300 ft (91 m) of the Chainman Shale. The fault under-
lies virtually all the Ely Limestone along the west
flank of the trough except for the Foote Range. The
fault is not present at any point on the east side of the
trough and is believed to have died out along bedding
somewhere beneath the trough or on its west flank.
The allochthonous Ely Limestone and most of the
Arcturus are interpreted as belonging to the inter-
mediate plate everywhere along the west flank of the
trough except in the Foote Range. The Ely Limestone
of the Foote Range, along with the Chainman Shale
and older units along the remainder of the west flank
of the trough, are interpreted as composing the lower
plate.

EVIDENCE FOR THE HIGHER DECOLLEMENT

The geologic map (pl. 1) has been generalized from
detailed maps originally published at a scale of
1:24,000 (pl. 1, index). A consequence of this generali-
zation is removal of much of the detailed data that
document the existence of the two décollements. A
brief review of the documentation is presented here, for
although the fault surfaces, particularly the higher
one, crop out at many places, they are mostly inferred.

At Desolation anticline, four rather persistent lime-

 

stone beds (A to D in ascending order) in an interval
from 500 to 600 ft (150 to 180 m) thick were mapped in
detail in the upper Arcturus by Hose and Repenning
(1963) and Hose and Ziony (1963). Overall, the beds
define a smoothly curved anticlinal fold, but high in
the section, as the upper plate is approached, the
Arcturus is severely deformed. Just west of the Disap-
pointment Hills and north of the Cowboy Pass NW
quadrangle, the D bed lies just below the fault surface
and is strongly deformed. Nevertheless, it extends
nearly as far north as the north end of the Disappoint-
ment Hills, as do the A and B beds (C bed was not
mapped north of the Cowboy Pass quadrangle).

About 11/2 mi (2.4 km) east of the northermost oc-
currence of the A, B, and D beds, on the east side of the
upper plate (Disappointment Hills), the A—D interval
is missing altogether from the intermediate plate. It
seems unlikely that this disappearance is due to
stratigraphic wedging out in View of the fact that some
of these beds (A and B) extend nearly the entire length
of the map area with only minor changes in lithology.
Furthermore, in the position that the limestone beds
should have occupied is a severely deformed gypsifer-
ous sandstone sequence of Arcturus that is underlain
by lower Arcturus with relatively uniform west dips
and overlain by about 30 feet (10 km) of upper
Arcturus that conformably underlies the Kaibab and is
part of the upper plate.

In the southeastern part of the Desolation anticline,
the Gerster Limestone or Plympton Formation are in
several places in fault contact with the upper Arcturus.
The fault is well exposed and gently dipping in this
area.

Figure 2 presents an example of general interme-
diate-upper plate relations.

The elongate folds in the allochthonous block under-
lying Plympton Ridge are terminated by a high-angle
fault at the northwest end (fig. 2). Abutting that fault
on the northwest is a synclinal block of Kaibab Lime-
stone which is an offset element of a syncline that ex-
tends virtually the entire length of Plympton Ridge.
This small offset element in effect demonstrates the
relations between the upper plate and the inter-
mediate plate for all of Plympton Ridge. Beds A—D are
continuous across the syncline on the west of Desola-
tion anticline. The A and B beds also continue around
the southwest side of the offset element, but the C and
D beds are overturned and were cut off by the décolle-
ment so that as much as 400 ft (120 m) of strata was
removed along the southwest side of the offset and
southward along the entire west side of Plympton
Ridge. To account for the removal of the C and D beds,
a fault must be inferred above the B bed and below the
upper 30 ft (10 m) or so of Arcturus, which is part of the

STRUCTURES WITHIN THE STRUCTURAL TROUGH 5

 

 

113°46’ “3045'
o , R. 17 w.
39 29 :; EXPLANATION
Pp
Park City Group

 

 

 

 

l
PERM IAN

 

 

 

Arcturus Formation
A — D, keybeds

 

Ely Limestone
Dashed line represents

 

 

  
 
 

I
MISSISSIPPIAN,
PENNSYLVANIAN,
AND PERMIAN

base of Permian _

Contact
—J_.__
T. High-angle fault
15y, Bar and ball on downt/zrown side
S. Arrows show relative horizon tal movement
_A_A_A__A_A_

Low-angle fault
Suwteeth on upper plate

Syncline

 

39° 27'

 

 

 

Showing trace ofaxial plane

+

Antiform in
overturned beds

—ifl—

Synform in
overturned beds

 

 

0
l
l7 |
O 1 KILOMETRE

1M|LE

FIGURE 2.—Generalized geologic map of northwest end of Plympton Ridge (Modified from Hose and Ziony, 1963).

upper plate. The position of the fault in the missing
C—D interval requires that the fault be subparallel to
the bedding in the Arcturus of the intermediate plate
and coincidentally subparallel to the bedding in the
lower part of the upper plate, or that the fault origi-
nally had about the same strike as the bedding. The
bedding in the upper and intermediate plates locally is
overturned along the west side of Plympton Ridge, as

so must be the upper décollement. Near Cowboy Pass
the 0—D interval is present, thus further precluding
any possibility that the missing interval resulted from
some stratigraphic phenomenon. Furthermore, a de-
formed gouge zone is present in some places at the
upper-intermediate plate boundary around the offset,
and if the fault underlies the offset, it must also under-
lie the rest of Plympton Ridge. Elsewhere the presence

6 STRUCTURAL GEOLOGY OF THE CONFUSION RANGE, UTAH

of the upper décollement is demonstrated by severe
deformation in the higher parts of the intermediate
plate.

EVIDENCE FOR THE LOWER DECOLLEMENT

Evidence for the lower décollement is based mainly
on the absence of strata at various places northwest,
north, and east of the Bishop Spring anticline. The
upper Chainman Shale and lower Ely Limestone of the
northern Foote Range are well exposed and the se-
quence is clear, so there is little doubt that strata are
removed along the trace of the fault in the area east of
the Foote Range (pl. 1, F—F’). The concealed position of
the trace southward from the latitude of Bishop Spring
anticline, however, is uncertain because of the depth of
Tertiary and Quaternary cover.

A relation comparable to that east of Bishop Spring
anticline exists in the Conger Range where missing
upper Chainman and lower Ely indicate faulting. Ad-
ditional evidence appears in a fenster close to the west
side of the Buckskin Hills (pl. 1, H—H’, and I—I’). A
geologic map of White Pine County, Nev. (Hose and
Blake, 1970), to the west, also shows several areas
where the upper Chainman Shale—lower Ely Lime-
stone is the locus of low-angle décollement faulting.

STRUCTURES OF THE UPPER PLATE

Cross sections accompanying maps of the Confusion
Range (Hose, 1963a, b; 1965a, b; 1966, 1975a, b; Hose
and Repenning, 1963) show that the upper plate is syn—
clinal and forms the core of the Confusion Range struc-
tural trough at least from Rattlesnake Bench north-
ward to the north end of the map area as well as a few
outliers in the area just northwest of the Conger
Range. Within this synclinally folded allochthon, there
are two common fold types: those that are nearly iso-
clinal with vertical to recumbent axes and those that
are broad and open. The isoclinal folds characterize the
northern part of the Disappointment Hills; the more
open folds, the southern part from the southern Disap-
pointment Hills to the south end of the upper plate
near Rattlesnake Bench. Plympton Ridge, which is
also part of the upper plate, contains tight folds that
are overturned to the east. Plympton Ridge also has a
much more pronounced bend in it than the contiguous
area of more open folds on the east with which it is in
fault contact.

Displacement on the thrust within the upper plate in
the Disappointment Hills (pl. 1, D—D’ and E—E ’) moved
units as old as the Arcturus Formation and the Kaibab
Limestone relatively westward over units as young as
Triassic. The thrust becomes vertical just north of the
latitude of the central part of Plympton Ridge, and in

 

places the relative displacement of the high-angle ex-
tension suggests a throw that is down on the east
rather than up, as it is to the north where clearly low
angle. Such a contrast in throw could be resolved if
there were an element of left-transcurrent motion on
the fault or later vertical movement.

Displacement on a second thrust cutting the upper
plate southeast of Cowboy Pass (pl. 1) moved Permian
beds, the Kaibab and Plympton, over Triassic units;
here, the movement of the hanging wall of the thrust is
clearly to the southeast. This thrust dies out just north
of Rattlesnake Bench, but to the northeast it effects a
contrast in trends of about N. 45°—55° E. in the upper
plate to about north-south to N. 35° E. on the average
in the lower plate. It seems likely that the broad open
syncline just north of Cowboy Pass (pl. 1, F—F’ and
G—G'), which is certainly a part of the upper plate of
the thrust southeast of Cowboy Pass, is continuous
northward to the southern Disappointment Hills
where it is also part of the upper plate of the thrust of
the western part of Disappointment Hills. This syn-
clinal unit then is the upper plate of two rooted thrusts,
one to the north that moved rocks relatively west and
the other in the south that moved rocks relatively
southeast (pl. 1, Disappointment Hills—Plympton
Ridge and northeast of Rattlesnake Bench; D—D’,
E—E’, and G—G’).

Two additional details of the upper plate structures
are cited here because of their bearing on interpreta-
tions of the genesis of the entire upper plate. Along the
west edge of and within the upper plate in the northern
part of the Disappointment Hills is a flaplike recum-
bent fold with its lobe directed eastward into the axis of
the structural trough (pl. 1, A—A’, B—B’, and C—C’).
The south end of the flap has a steep southerly plunge
and is believed to die out in a short distance beneath
right-side-up beds. A second flaplike fold is present
4—5 mi (6-8 km) south of the north end of the map area
on the east side of the upper plate (D—D’, E—E’). The
lobe of this flap is directed westward into the axis of the
structural trough.

STRUCTURE OF THE INTERMEDIATE PLATE

The intermediate plate in part outlines the west
flank of the Confusion Range structural trough. The
west edge of the plate is defined by the trace of a near
bedding plane fault that is cut in the upper Chainman
Shale and lower Ely Limestone. Since no fault at a
comparable stratigraphic position is present on the
east side of the trough, it is believed that the fault died
out somewhere in the subsurface beneath the trough.
Accordingly, the intermediate and lower plates merge
into a single plate on the east side of the trough. The

OTHER STRUCTURES 7

fault surfaces that mark the base of both the inter-
mediate and upper plates have the same synclinal form
as the structural trough.

Beds in the higher parts of the intermediate plate
where they are close to the upper décollement are se—
verely compressed into tight, small-amplitude folds. In
the area directly northwest of Plympton Ridge, the D
bed of the Arcturus Formation (Hose and Ziony, 1963)
is overturned and upside down for a distance of half a
mile. The beds in this flaplike upside-down element are
locally sharply folded. The direction of overturn
suggests that the upper plate moved in an easterly
direction. Except for this severe deformation high in
the intermediate plate, the folds of the intermediate
plate are much broader and of larger amplitude than
those of the upper plate.

The intermediate plate occupies the axial region of
the structural trough. Throughout the northern two-
thirds of the map area, the intermediate plate is partly
overlain by the upper plate, and so a complete view of
the axial structures is not available. In the southern
third of the map area, where erosion has exposed most
of the intermediate plate, the most conspicuous feature
is a faulted anticlinal fold along the very axis of the
structural trough. Interpretive cross sections (pl. 1,
H—H’ and I—I’) show both flanks of the faulted anticline
to be overturned in the southern Conger Range but
overturned only to the west in the northern part. The
overturns plus complex faulting give the fold a mush-
room shape in cross section in the southern part of the
Conger Range. In the southern part of the Conger
Range (pl. 1,1—1’), the anticline is flanked on both sides
by synclines, but the syncline on the east in the north-
ern part of the Conger Range is partly cut out by a
reverse fault. This fault and the precise anticline-
syncline relation are obscured by Quaternary cover in
the vicinity of Brown’s Wash. The slight northerly
plunge of about 15° of the anticline suggests that it
may die out beneath the upper plate, and so the inter-
mediate plate may be wholly synclinal beneath the
upper plate.

At the latitude of Plympton Ridge, both the upper
and intermediate plates are more concave to the west
than either the lower plate or the axis of the structural
trough. The area where the concavity is greatest is the
area of greatest overturn of the upper décollement as
well as the intermediate plate.

OTHER STRUCTURES

CONGER RANGE FAULT

Two large faults have had a profound effect on the
structure and thus deserve mention. Of these two, the
larger is the Conger Range fault, which offsets both of

 

the décollement faults and therefore is younger. It is
overlapped by Tertiary sedimentary and volcanic rocks
as young as 29 my, and also it is older than the Basin
and Range orogeny. The fault is composite, arcuate,
and high angle. It borders the lower and middle
Paleozoic rocks of the western part of the Conger
Range and where it trends easterly, cuts directly a-
cross the structural trough; on the east it trends south
beneath Tertiary sedimentary and volcanic rocks. The
maximum stratigraphic displacement is more than
2 mi (3.2 km) at the southwest end, diminishing to
perhaps 1,000 ft (305 m) at the east terminus of expo-
sure. The apparent offset of the anticline in the axis of
the intermediate plate is more than a mile (1.6 km).

SALT MARSH RANGE FAULT

The Salt Marsh Range fault flanks the range on the
southeast and trends northerly. The attitude of the
fault surface is unknown, but it is probably steep and
up on the west. The fault has moved Middle Devonian
strata on the west against the Ely Limestone, indicat-
ing a stratigraphic displacement of more than 4,000 ft
(1,200 m). The areas to the north and south of the Salt
Marsh Range are covered by Quaternary deposits, and
the continuation of the fault is unknown. However, the
scattered outcrops east of the northern part of the Salt
Marsh Range suggest that the trend changes to nearly
due north; the fault may die out to the north and also to
the southwest. Although the age of this fault is uncer-
tain, it may have formed during the Basin and Range
orogeny, but direct evidence is lacking.

BASIN AND RANGE OROGENY

A large measure of the present physiography of the
Basin and Range province was imposed by the Basin
and Range orogeny. This event was extensional and
produced steep fault scarps and high relief on one or
both flanks of most of the ranges of the province. The
total extension across the province has been estimated
by Thompson and Burke (1973) to be about 62 mi
(100 km), on the basis of careful geologic and geophysi-
cal work in Dixie Valley, Nev. To account for the rela-
tively uniform array of mountain ranges and basins
across the province, Stewart (1971) attributed the
structures to deep-seated extension of a plastic sub-
strate.

It is fairly certain that the development of the basins
and ranges occurred over a long period, probably start-
ing as early as Oligocene and continuing to the present
(Nolan, 1943, p. 183). It is also possible that the event
climaxed at different times in different places. In east-
central Nevada it is believed to have reached a climax
in the late Miocene (Hose and Blake, 1976).

8 STRUCTURAL GEOLOGY OF THE CONFUSION RANGE, UTAH

Precise dating of a tectonic event requires the pres-
ence of a sequence of datable rock whose age closely
brackets the event. In the Confusion Range the Basin
and Range orogeny can be dated no closer than post-
28—29 m.y. (the late Oligocene age of welded ash flows
at Toms Knoll in the Conger Range quadrangle and at
Cowboy Pass and other places) and pre-late Tertiary.

Block faulting is negligible or at least uncharacteris-
tic in the northern Confusion Range, inasmuch as the
prominent range-front scarps so common elsewhere
are here uncommon and relief is low. A Basin and
Range fault may have produced the scarp on the west
flank of the Salt Marsh Range, however, and may ex-
tend a considerable distance to the north and south,
buried beneath Quaternary pediment veneer. The
large Conger Range fault complex that produces the
prominent scarp along the west to north margin of the
Conger Range, however, is overlapped depositionally
by the limestone that underlies the 28—29-m.y.-old
welded ash flows. The southern part of the Confusion
Range beyond the map area to the east and southeast
is somewhat more typical, as it does have steep scarps.
No doubt Basin and Range faults cut the older faulted
terrane, but differentiation of these, where Tertiary
rocks are absent, is impossible. The sharp contrast in
the abundance of faults in the Paleozoic and Triassic
terrane with the sparsity of faults cutting the
Oligocene rocks in the Conger Range is probably rep-
resentative of the whole Confusion Range. Oligocene
volcanic rocks and limestone are cut by a fault along
the west side of Toms Knoll.

SUMMARY AND CONCLUSIONS

As the Confusion Range structural trough de-
veloped, the flanks became steeper. When some un-
known critical slope was reached, competent units
high in the section sheared loose from weak gypsifer—
ous zones of the upper Arcturus Formation and moved
in a quasi-viscous manner toward the axis of the
trough. The inward-directed movement of this upper
plate produced isoclinal and recumbent folds whose
basal disharmonic surfaces became coincident with the
major glide surface, or décollement. The occurrence of
recumbent folds with opposing directions of overturn
toward the axis of the Confusion Range structural
trough is best explained by gravity sliding and would
have evolved as shown schematically in figure 3. The
present configuration of the structural trough (pl. 1,
A—A’ to E—E’) shows some isoclinal and recumbent
folds. Significantly the lobes of the recumbent folds are
directed toward the axis or direction of movement. In
sections B—B’ and C—C’ the lobe is directed to the east
and suggests eastward movement of the upper plate;
sections D—D’ and E—E ’ show the lobe of the east flank

 

 

 

 

 

FIGURE 3.—Schematic cross sections showing stages of development
(1—4) of décollement and thrust faults and folds in axial part of
Confusion Range structural trough. Arrows show movement direc-
tion on faults; datum formation (such as the Kaibab Limestone) is
shaded.

directed toward the west.

The intermediate plate formed in a similar way to
the upper plate, but it developed on a lower strati-
graphic level and was confined to the west flank. It
played an important role in the present configuration
of the structural trough. Although it is believed to ex-
tend nearly the whole length of the map area (pl. 1,
D—D’ to I—I’), it seems to have had its maximum rela-
tive eastward movement at the latitude of Plympton
Ridge. At this latitude (pl. 1, F—F’) its movement pro-
duced an overturn of the upper and intermediate plates
and accentuated the westward concavity of the struc-
tural trough.

As a result of the two episodes of axially directed
gliding and flowage, the structural trough was filled

REFERENCES CITED 9

with folded rock. The presence of rooted thrust faults
that later cut this body of rock suggests that there was
a continued buildup of stress in the axial part of the
trough that was relieved by thrusting away from the
axis (to the west in pl. 1,D—D’ and E—E' and to the east
in G—G’). The nature of this stress is unknown but
could have been regionally compressive and quite dif-
ferent from the local compressive stress that produced
the axial folds.

REFERENCES CITED

Drewes, Harald, 1967, Geology of the Connors Pass quadrangle,
Schell Creek Range, east-central Nevada: US. Geol. Survey
Prof. Paper 557, 93 p.

Hintze, L. F., 1963, Geologic map of southwestern Utah: Utah State
Land Board.

Hose, R. K., 1963a, Geologic map and sections of the Cowboy Pass
NE quadrangle, Confusion Range, Millard County, Utah: US.
Geol. Survey Misc. Geol. Inv. Map I—377.

1963b, Geologic map and sections of the Cowboy Pass SE

quadrangle, Confusion Range, Millard County, Utah: US. Geol.

Survey Misc. Geol. Inv. Map I—391.

1965a, Geologic map and sections of the Conger Range NE

quadrangle and adjacent area, Confusion Range, Millard

County, Utah: US Geol. Survey Misc. Inv. Map I—436.

1965b, Geologic map and sections of the Conger Range SE

quadrangle and adjacent area, Confusion Range, Millard

County, Utah: US. Geol. Survey Misc. Geol. Inv. Map I—435.

1966, The Confusion Range structural trough, Utah [abs]:

Geol. Soc. America, Cordilleran Sec., Seismol. Soc. America, and

Paleont. Soc., Pacific Coast Sec., 62d Ann. Mtg, 1966, Reno,

Nev., Program, p. 45.

1975a, Geologic map of the Trout Creek SE quadrangle: U.S.

Geol. Survey Misc. Geol. Inv. Map I—827.

 

 

 

 

 

I}U.S. GOVERNMENT PRINTING OFFICE: 1976 - 789-025/13

 

—1975b, Geologic map of the Granite Mountain SW quadrangle:
U.S. Geol. Survey Misc. Geol. Inv. Map 1—831.

Hose, R. K. and Blake, M. 0., Jr., 1970, Geologic map of White Pine
County, Nevada: US. Geol. Survey open-file map.

1976, Geology of White Pine County, Nevada: Nevada Bur.
Mines and Geology Bull. (in press).

Hose, R. K., and Danés, Z. F., 1967, Late Mesozoic structural evolu-
tion of the eastern Great Basin [abs]: Geol. Soc. America and
associated societies, Ann. Mtg, 1967, New Orleans, La., Abs.
with Program, p. 102.

1973, Development of the late Mesozoic to early Cenozoic
structures of the eastern Great Basin, in DeJong, K. A., and
Scholten, Robert, eds, Gravity and tectonics: New York, John
Wiley and Sons, p. 429—441.

Hose, R. K., and Repenning, C. A., 1963, Geologic map and sections
of the Cowboy Pass NW quadrangle, Confusion Range, Millard
County, Utah: US. Geol. Survey Misc. Geol. Inv. Map I—378.

Hose, R. K., and Ziony, J. I., 1963, Geologic map and sections of the
Gandy NE quadrangle, Confusion Range, Millard County, Utah:
US. Geol. Survey Misc. Geol. Inv. Map I—376.

Miller, G. M., 1966, Structure and stratigraphy of southern part of
Wah Wah Mountains, southwest Utah: Am. Assoc. Petroleum
Geologists Bull., v. 50, p. 858—900.

Misch, Peter, 1960, Regional structural reconnaissance in central—
northeast Nevada and some adjacent areas—Observations and
interpretations: Intermountain Assoc. Petroleum Geologists
11th Ann. Field Conf. Guidebook, p. 17—42.

Nolan, T. B., 1943, The Basin and Range Province in Utah, Nevada,
and California: US. Geol. Survey Prof. Paper 197—D, p. 141—
196.

Stewart, J. H., 1971, Basin and Range structure; A system of horsts
and grabens produced by deep-seated extension: Geol. Soc.
America Bull., v. 82, no. 5, p. 1019—1044.

Thompson, G. A., and Burke, D. B., 1973, Rate and direction of
spreading in Dixie Valley, Basin and Range Province, Nevada:
Geol. Soc. America Bull., v. 84, no. 2, p. 627—632.

 

 

 

TRUE NORTH

APPROXIMATE MEAN

113°52’30"

39°37 '30"

UNITED STATES DEPARTMENT OF THE INTERIOR
GEOLOGICAL SURVEY

 

 

15'

 

39”00'

Qu

     
 

 

 

1 13°52’30"

39°00'
113°45'

1;

Upper plate

Intermediate plate
JL

Lower plate
1L

 

SCALE 1:125 000

4

   
    

113° 37'30"

113°37’30"

 

39°37’30"

 

EXPLANATION

 

Qu

 

 

 

Quaternary
unconsolidated deposits

 

Younger Tertiary
sedimentary rocks
(Pliocene)

Older Tertiary
volcanic and sedimentary
rocks (Oligocene)

JK J\_________JR,—/
PERMIAN

TRIASSIC

Thaynes Formation

 

Park City Group

 

 

 

  

 

 

Lower plate

 

I,___~_________________________________________

MNHTE(TULB

VALLEY

Qu

 

 

 

 

Laketown Dolomite

 

Fish Haven Dolomite;
Eureka Quartzite, and
Pogonip Group

I
\ J; "JW—J

CAMBRIAN ORDOVICIAN SILURIAN

Cambrian rocks
undivided

Contact

Dotted where concealed

 

Fault

Dotted where concealed

____.._L....L..

Low-angle fault

Dotted where concealed
Sawteeth on upper plate

Anticline

Showing trace of crestal plane and direction
of plunge. Dotted where concealed

Overturned anticline
Dotted where concealed

Syncline

Showing trace of trough plane
Dotted where concealed

Overturned anticline
Dotted where concealed

+

Axis of Confusion Range

 

 

M
1 b

. z”
Arcturus Formation :3 {>2 Q
gee?
3E2:
Ely Limestone a Z S m
I—t I-I-I Z 94
g 9..
Z
3 s
'— 9..
> Z O 9..
Chainman Shale, Joana 0 <2: 5
Limestone, and Pilot [5 2
Shale J Q a
....
, ‘ \ 2
Z
Guilmette Formation 5
Z
?c
>
LII
D
Simonson and Sevy
Dolomites
6 8 10 MILES
a ,____d
8 110 KILOMETRES

 

 

structural trough

 

113°30'
39°30'
-€
Dg
. %
\ 0
a
0 <3

 

 

PROFESSIONAL PAPER 971
PLATE 1

 

 

Note: Contacts between formations are shown within the Park City Group.
Key beds are shown within the Arcturus Formation

 

 

 

 

 

 

 

 

113°30'

 

 

 

 

 

 

 

 

 

39C15'
113°30'
113°52'30" 45' 37'30"
39°37'30"
TROUT GRANWE
CREEKSE MTN.SW
[—827 l—831
3o
GANDY cowaov cowaov
NE PASS Nw PASS NE
l—376 I—378 I—377
GANDY cowsov cowsov
SE PASSSW PASSSE
1-393 1-390 I—391
15
CONGER
RANGE
NE
I—436 ________1—‘——_—
CONGEH '
RANGE UTAH
SE
1—435
39°oo'

INDEX MAP OF PART OF CONFUSION RANGE SHOWING
LOCATION AND NUMBER OF PUBLISHED MAPS

 

O——O

“u"

 

 

 

 

 

 

127 Interior—Geological Survey, Menlo Park, CA.—1976—-G76057

SCALE 1:48 000

2 3 MILES
I I
I I |
4 KILOMETRES

CHEPIEHRAJLEZEHD’CHECHLCK}DC3BJAJP(DF‘ALIEAI117()F‘THHIE(ZCHNFWJEHIIBIILAIICHE,VVIMSTLCHEPTTTiAJ;IJUHAII

 

if: 5"". 7 DAYS

Correlation of Late Cenozoic Tuffs in the
Central Coast Ranges of California

by Means of Trace- and
Minor-Element Chemistry

 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 972

 

 

7:}‘1‘
( ,‘y I)

 

NW 1975

U.S.S.D.

Correlation of Late Cenozoic Tuffs in the

Central Coast Ranges of California
by Means of Trace- and
Minor—Element Chemistry

By Andrei M. Sarna—Wojcicki

 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 972

 

A geochemical approach to the correlation of
tufls in Pliocene and Pleistocene marine and
nonmarine strata of central California

 

 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1976

r ,1. :.~-__ ,.
" Kiel»

UNITED STATES DEPARTMENT OF THE INTERIOR

THOMAS S. KLEPPE, Srrrrtm)‘

GEOLOGICAL SURVEY

V. E. McKelvey, Director

Library of Congress Cataloging in Publication Data

Sarna-Wojcicki, Andrei M.
Correlation of late Cenozoic tuffs in the central coast ranges of California by means of trace- and minor-element chemistry.

(Geological Survey Professional Paper 972)

Bibliography: p. 29-30.

Supt. of Docs. no. I 19.161972

1. Volcanic ash, tuff, etc. California—Coast Range. 2. Stratigraphic correlation—California—Coast Range. 3. Geochemistry—
California—Coast Range. 4. Geology, Stratigraphic—Cenozoic. I. Title: Correlation of late Cenozoic tuffs in the central
coast ranges of California... II. Series: United States Geological Survey Professional Paper 972.

QE461.S324 552'.2 76—608254

 

For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, DC. 20402
Stock Number 024—001-02880—8

CONTENTS

 

Page Page
Abstract ____________________________________________________ 1 Discussion __________________________________________________ 24
Introduction and scope of study ______________________________ 1 Description of units ________________________________________ 26
Acknowledgments ______________________________________ 1 Thick sections of volcanic deposits ______________________ 26
Geologic setting ____________________________________________ 3 Sonoma Volcanic, Monticello Road section, southeastern
Sonoma volcanic field __________________________________ 3 part of Sonoma volcanic field, east of Napa ________ 26
Clear Lake volcanic field ________________________________ 4 Sonoma Volcanics, southernmost Sonoma volcanic field
Southern Cascade Range volcanic field __________________ 4 north of Suisun Bay (Goodyear Station section) ____ 26
Analytical methods ________________________________________ 4 Pinole Tuff ________________________________________ 26
Refractive indices of glass ______________________________ 4 Widespread tuffs interbedded with detrital sedimentary
Mafic-mineral analysis __________________________________ 4 deposits __________________________________________ 27
X-ray fluorescence spectrometric analysis ________________ 4 Western part of the main study area ________________ 27
Methods of evaluating chemical data ________________________ 7 Tuff in the type section of the Merced Formation__ 27
Graphic methods ________________________________________ 7 Tuff in the Merced(?) and Petaluma Formations of
Similarity coefficient ____________________________________ 8 Sonoma County ______________________________ 27
Cluster analysis ________________________________________ 8 Southeastern part of the main study area ____________ 27
Results of analyses __________________________________________ 9 Lawlor Tuff ____________________________________ 28
Tuff correlations ____________________________________________ 14 South of Mount Diablo __________________________ 28
Tuff in the Merced(?) Formation of Sonoma County ________ 15 Northeastern part of the study area __________________ 29
Pinole Tuff ____________________________________________ 16 Putah Tuff Member of the Tehama Formation ____ 29
Lawlor Tuff ____________________________________________ 16 Nomlaki Tuff Member of the Tehama Formation -_ 29
Putah and Nomlaki Tuff Members of the Tehama Formation 21 References cited ____________________________________________ 29
Tuff in the type section of the Merced Formation __________ 23
ILLUSTRATIONS
Page
FIGURE 1. Generalized geologic map showing location of samples, central Coast Ranges ________________________________________ 2
2. Stratigraphic section exposed along Monticello Road, southeastern part of Sonoma volcanic field _____________'_ ________ 4
3. Cross section showing structure of Sonoma Volcanics in vicinity of Monticello Road __________________________________ 5
4. Similarity coefficient matrix comparing trace- and minor-element analyses of all glass samples analyzed ______________ 10
5. Dendrogram from cluster analysis of all analyzed samples ___________________________________________________________ 12
6. Ternary diagram showing provincial differences between tuffs in central Coast Ranges and southern Cascade Range ____ 15
7. Binary diagram showing provincial differences between tuffs in central Coast Ranges and southern Cascade Range ____ 15
8. Maps showing maximum known areal distribution of five major eruptive tuff units __________________________________ 16
9. Correlation chart of late Cenozoic tuffs _____________________________________________________________________________ 18
10. Histogram of principal mafic mineral frequencies of three size fractions of tuff in the Merced(?) Formation of Sonoma
County _______________________________________________________________________________________________________ 20
11. Ternary diagram showing correlation of the Pinole Tufi' with volcanic deposits of the Sonoma Volcanics exposed along
Monticello Road east of Napa _________________________________________________________________________________ 20
12. Ternary diagram showing correlation of the Pinole Tufl' with tuffs in Tessajara area south of Mount Diablo ____________ 20
13. Diagram showing correlation of the Pinole Tuff at Rodeo with tuffs south of Mount Diablo, in the Highland syncline sec-
tion, Tassajara area ___________________________________________________________________________________________ 20
14. Histograms of concentrations of minor and trace elements in volcanic glass of the Lawlor Tuff and its correlatives _______ 20
15. Histograms of concentrations of minor and trace elements in volcanic glass of the Putah and Nomlaki Tuff Members
the Tehama Formation _______-____________--________--_________-_-__-___________-__________-__----___, _______ 21
16. Similarity coefficient matrix comparing trace- and minor-element analyses of glass samples of the Putah Tuff Member
and tuff in the Merced(?) Formation of Sonoma County __________________________________________________________ 22
17. Dendrogram from cluster analysis of trace- and minor—element data, using distance function ____________________________ 23

III

IV

TABLE

SQP‘PPPE“

CONTENTS
TABLES

Page
List of units studied _______________________________________________________________________________________________ 6
Analytical data on potassium-argon dates _________________________________________________________________________ 7
Summary of X-ray fluorescence spectrometer analytical conditions __________________________________________________ 7
Comparison of glass compositions of a silicic and an intermediate tuf‘f ________________________________________________ 9
Chemical analyses and petrographic data ___________________________________________________________________________ 13
Average minor- and trace-element composition of volcanic glass of the Lawlor Tuff and correlative localities ____________ 21
Trace- and minor-element analyses of volcanic glass of two thin water-laid tuffs in the Livermore Gravels of Clark
(1930) _______________________________________________________________________________________________________ 21

Average similarity coefficients comparing trace- and minor-element analyses of volcanic glass of two thin water-laid tuffs
in the Livermore Gravels of Clark (1930) _______________________________________________________________________ 22

CORRELATION OF LATE CENOZOIC TUFFS IN THE
CENTRAL COAST RANGES OF CALIFORNIA BY MEANS OF
TRACE- AND MINOR-ELEMENT CHEMISTRY

By ANDREI M. SARNA-WOJCICKI

ABSTRACT

Deformed late Cenozoic tuffs in the central Coast Ranges of
California have been correlated by means of trace- and minor-
element chemistry of volcanic glass, supported by potassium-argon
dates, petrographic data, and stratigraphy. Cluster analysis of the
chemical data indicates that four orders of chemical variability exist
in the trace- and minor-element composition of volcanic glass. The
greatest differences are between tephra of silicic and intermediate
composition. Considering silicic tephra alone, the greatest differ-
ences are observed between tephra erupted in different volcanic
provinces. Differences between samples of silicic tephra erupted
within the same volcanic field are smaller, while the smallest differ-
ences are observed between samples of tephra from individual erup—
tions.

Five widespread tuffs and composite tephra units erupted during a
period from approximately 1 to 6 million years ago have been recog-
nized in the study area. These include the tuff in the type section of
the Merced Formation, the Putah Tuff Member of the Tehama For-
mation, the Lawlor Tuff, the Pinole Tuff and the tuff in the Merced(?)
Formation of Sonoma County. All except the first were erupted from
local central Coast Range sources, probably in the Sonoma volcanic
field; the tuff in the type section of the Merced Formation was de-
rived from the southern Cascade Range, about 320 km north of the
main study area.

Tufi' correlations indicate that Suisun Bay and Mount Diablo, in
the eastern part of the main study area, were formed less than 4
million years ago and that drainage from the Great Valley of
California to the ocean in the vicinity of the San Francisco Bay was
established some time between 0.6 and 3.3 million years ago.

INTRODUCTION AND SCOPE OF STUDY

Correlations between the discontinuous exposures of
deformed Pliocene and lower Pleistocene strata in the
central Coast Ranges of California are important to an
understanding of late Cenozoic development of the re-
gion because the distribution and structure of these
strata record the tempo and style of ongoing deforma-
tion in the Coast Ranges. However, late Cenozoic
sedimentation has been too rapid and has occurred
under environmental conditions too diverse to permit
refined correlation on the basis of fossil chronology.
Radiometric dating of these geologically young de-
posits lacks sufficient precision as a correlation tool
owing to the large errors involved in correcting for at-
mospheric argon-40 in the potassium-argon method,

 

the effect of detrital contamination, and the general
scarcity of material suitable for dating Within
sedimentary sections.

Because of the problems in fossil and radiometric age
correlation, many of the late Cenozoic deposits in the
central Coast Ranges are lumped into a broad, ill-
defined "Plio-Pleistocene” category. A more detailed
regional correlation of these deposits on the basis of
tephrochronology, supported by radiometric, strati-
graphic, and paleontological data, can serve as one of
the basic tools in the solution of several longstanding
geologic problems, such as the late Cenozoic
paleogeography of the Coast Ranges and the nature
and rates of late Cenozoic deformation.

The principal approach to correlation discussed in
this paper is that of geochemical tephrochronology—
comparison of tuff beds in these deposits by means of
minor- and trace-element compositions of the volcanic
glass (chemical fingerprinting method of Jack and
Carmichael, 1968). Other comparative methods, such
as mafic-mineral frequency analysis, refractive indices
of glass, and potassium-argon dating of some of the
main tuff units, serve to support the correlations based
on this chemical fingerprinting of the tuff units.

This paper is mainly concerned with the results of
tuff correlations and their geologic implications. A
more detailed discussion of methods and the relative
merits of various correlation criteria can be found in
the author’s dissertation (Sarna-Wojcicki, 1971).

This study is limited to middle and late Pliocene and
early Pleistocene deposits in the central Coast Ranges
of California, between lat. 37°30’ N. and 38°45’ N.
(fig. 1). Some tuff units and volcanic sources outside of
this region, in the Clear Lake area and northern Great
Valley, were also studied (inset map, fig. 1).

ACKNOWLEDGMENTS

This report is based partly on a doctoral dissertation
submitted in 1971 to the Department of Geology and
Geophysics, University of California, Berkeley, and

1

CORRELATION OF LATE CENOZOIC TUFFS, COAST RANGES, CALIFORNIA

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5 § 2 g Major wide- Major fault . Sample
0 _ .
Late Cenozo c sed' E E a: Clear Lake :2 Sonoma -volcanic 353:“ mff 3:112:35; wfigrcifepgroxt locallty
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FIGURE 1.—Generalized geologic map showing location of samples, central Coast Ranges, Calif. Geology from Strand
and Koenig (1965), Koenig (1966), Rogers (1966), Jennings and Burnett (1961), and Ross Wagner (written com-

mun., 1974).

 

GEOLOGIC SETTING 3

partly on research performed during 1971—72 at the
US. Geological Survey.

I thank the following people at the Department of
Geology and Geophysics at Berkeley: Robert Jack, who
instructed me in XRF analytical procedures and
helped in the analyses; Frank H. Brown, who did elec-
tron microprobe analyses of volcanic glass and pheno-
crysts; Richard L. Hay, Clyde Wahrhaftig, and Donald
Savage, who advised me in this research; Garniss H.
Curtis, who ran potassium-argon dates on several of
the tuff samples in this study; Leonard Vigus, who
helped with construction of research equipment;
Leonard Leudke, who prepared and polished micro-
probe samples; and Katherine Condon, who helped in
laboratory preparation of tuff samples.

Thanks are given to the following people at the US.
Geological Survey in Menlo Park: Alan Bartow, who
gave me information on the tuff in the Merced(?) For-
mation of Sonoma County; Brent Fabbi, who ran XRF
analyses on several tuff samples; Kenneth F. Fox, Jr.,
who advised me on the use of the cluster analysis pro-
gram; and Paul C. Russell, who did glass separation on
tuff samples and helped with the drafting.

I also thank Donald 0. Emerson, of the University of
California, Davis, for information on the Putah Tuff
Member.

I am grateful for a Penrose Grant from the Geologi-
cal Society of America and for a Graduate Research
Grant from the University of California.

GEOLOGIC SETTING

Late Cenozoic deposits in the central Coast Ranges
of California are discontinuous sedimentary and vol-
canic prisms occupying axes of northwest-trending
post-Miocene 'basins, dissected remnants mantling up-
lifted northwest-trending ranges, elongate truncated
edges of sedimentary prisms upwarped along zones of
flexure or faulting between areas of uplift and subsid-
ence, and elongate northwest-trending fault-bounded
slivers situated along major fault zones. Throughout
much of the central Coast Ranges, late Cenozoic de-
posits lap onto deformed rocks of Jurassic to Miocene
age along major unconformities and are themselves
strongly deformed.

Late Cenozoic deposits include both sedimentary and
volcanic rocks. In the western part of the area, marine
Pliocene and Pleistocene sediments are associated with
brackish-water deposits and freshwater alluvial and
lacustrine deposits of approximately the same age,
though the contact relations between them in most
places are concealed by younger alluvium or severed
by faults. For instance, the marine Merced(?) Forma-
tion of Sonoma County probably interfingers to the

 

east and northeast with the brackish-water and fresh-
water Petaluma Formation and with the freshwater
alluvial Glen Ellen Formation (Bartow and others,
1973), but the transition from one formation to the
other is nowhere continuously exposed. In the eastern
basins, the late Cenozoic 'sediments are mainly allu-
vial, fan, and lacustrine deposits. Throughout most of
the study area, the western basins are separated from
the eastern by northwest-trending ranges underlain by
older rocks. The volcanic rocks, restricted primarily to
the northern part of the study area, form thick and
extensive fields and interfinger locally with sedimen-
tary rocks. Pyroclastic rocks in the study area are
found as thick deposits interbedded with flow rocks
within the volcanic fields and thinner tuff units inter-
bedded with sedimentary deposits. Most of these thin-
ner units were probably derived from volcanic fields
within the study area. Such tuffs are fairly widespread
in late Cenozoic sections throughout the central Coast
Ranges, though they constitute but a small percentage
of the total sediment volume. These tuffs are a useful
tool in correlating stratigraphic sections between
widely separated areas, especially between marine and
continental sections and between sedimentary and vol-
canic sections for which fossil and radiometric data are
often inadequate. ‘

Tuffs interbedded in thick volcanic piles were closer
to eruptive centers; consequently they contain coarser
material than tuffs in the outlying areas. Two such
thick volcanic piles within the study area are the
Sonoma volcanic field and the Clear Lake volcanic
field, but a major potential source of tuffs from outside
the Coast Ranges is the area southwest of Mount Las-
sen, in the southern Cascade Range of northeastern
California (inset map, fig. 1).

SONQMA VOLCANIC FIELD

The term Sonoma volcanic field, as used herein,
refers to an area of middle and late Pliocene volcanism
in the northern part of the study area. The Sonoma
Volcanics, deformed and partially eroded, is the rock
formation defined by Weaver (1949) which represents
the present distribution of the Sonoma volcanic field.
This formation is composed of pyroclastic deposits and
lava flows with associated intrusive dikes. The rocks
are predominantly silicic but range in composition
from basalt to rhyolite. Two sections in the southeast-
ern part of the field were studied in detail: the Monti-
cello Road section east of Napa (fig. 1, locs. 17, 45—51)
and the Goodyear Station section a few miles north-
west of Suisun Bay (fig. 1, locs. 19—21). The Monticello
Road section consists of more than 600 m of tuff, brec-
cia, and flows of predominantly dacitic composition
(figs. 2 and 3).

The Clear Lake volcanic field (Becker, 1888; Ander-
son, 1936; Brice, 1952), northeast of the Sonoma vol-
canic field, was active during late Pliocene and

Sample No.
Age (K—Ar), in m.y.

47

CLEAR LA

tion, in metres
column

Elevation in sec-
Stratigraphic

<

<%
/

CORRELATION OF LATE CENOZOIC TUFFS, COAST RANGES, CALIFORNIA

KE VOLCANIC FIELD

Lithology

Pebble, cobble,and boulder conglomerate
in channels in top of tuff
\Reddish paleosol developed in top of unit

 

<<<

<

600 -

500 -

Tuff with rounded pumice Iepilli as
much as 2.5 cm long in fine-grained
matrix

Tuff with angular to subrounded lithic
fragments as much as 0.6 cm in die»
meter, and pumice lapilli as much as
2 cm in diameter; lithic fragments are
andesite and rhyolite or dacite(?)

Pumice-Iapilli tuff-breccia and pumice»
block breccia. Massive beds, 0.6—6 m
thick, of unsorted, angular, tubular,
light-bluishgray to dark-gray pumice
fragments 1.3—5 cm in average dia-
meter. Pumice blocks as much as 40 cm
long. Pumice has pearly sheen, is rather
dense and hard, with small vesicles.

.\

 

 

 

Matrix consists of pink to brown,
soft opaline(?) material and mont-

 

 

400 — —’~

300-

morillionite clay, together with vitric
ash. Locally, this unit contains welded
tuff near top

Blocks, as much as 1 m in diameter, of
banded dacite and perlite in matrix
of pumice breccia and vitric ash

Perlite, approximately 3 m thick

Light-purplish-gray to gray flow-banded
vescicular dacite. Flow banding is very
irregular, forming dome-and-basin
shapes several metres across. Flow
bands are spaced 1-8 cm apart. Ve-
sicles are localized along flow bands

Massive bluish-gray flow-banded dacite

Dacite

._\

Black, porphyritic pitchstone, 10-60 cm
thick, containing angular to round
lithic fragments (= welded zone7).Un-
derlain by a zone of welded dacite(?)

 

4.220.1‘

49

50 -5.4 20.21

51

<

200 —

 
  

breccia approximately 1.5 to 2 m thick,
containing lenses of gray porphyritic
glass

Lithic breccia and tuff-breccia, 6-9 m
thick; decrease in amount of lithic
fragments downward, with increase
in amount of vitric ash and pumice
lapilli

Creamy,light-gray to white chalkypumice
I'apilli and vitric-ash tuff

Andesite(?) dike

Narrow zone of welded dacitic(?) pumice-
Iapilli tuff containing lenses and stream-
ers of glass

Dark grayishvbrown andesitic ash tuff,
12 m thick, containing black to very
dark brown scoria Iapilli and bread
crust scoria bombs as much as 30 cm
in diameter

Light-gray to tannishvgray pumice-lapilli
and vitric-ash tuff, 1.5 m thick, in
thin beds rangingfrom afew centimetres

 

 

   

to 0.6 m thick, interbedded with
tuffaceous sandstonecontaining round-
ed pumice lapilli as much as 1.2 cm

 

long

Lower part of section (upper part of lower part may be partly or wholly correlative with upper part shown at right)

Quaternary time (Brice, 1953; G. H. Curtis, oral com-
mun., 1971). The volcanic rocks erupted in the Clear
Lake area range in composition from basalt to rhyolite.
Pyroclastic rocks are rare, suggesting that explosive
volcanic activity was unimportant in the development

 

 

 

 

 

 

 

 

 

 

>3
E o u.
.s 82 u
- ,4 : a --
2 :x ‘2 E i =
o 5‘ .9 E g. E
_ c. a. ._ _
o e ~ v o
E a s .5 E °
0) < Lu "‘ in Lithology
3° — v “—JLight-gray to white porphyritic rhyolite
45.141.820.12——~‘~ —‘ flow or welded tuffi?) containing an-
" gular lithic volcanic fragments g
” a 0 D”\Black porphyritic pitchstone or obsidian ‘5
2° ’ D with angular lithic fragments and pla- §
o o O gioclase feldspar phenocrysts (welded ._
I: ‘2 top of tuff sequence?) 2
0°C Light-tan to grey indurated welded tuff, 3
with flattened pumice-lapilli as much ‘1
V V as 1 3 cm Ian 5
1° ' \ ' g o.
\/ Gray crudely stratified poorly sorted d.
\/ \l pumice-Iapilli tuff D
46 V Gray, coarse pumice-Iapilli tuff. Lapilli
V V as much as 1.3 cm long
0
E i‘.‘
7 7 x a
It? c
o 3
6 V v “White massive unstratified coarsepumice- u g
lapilli tuff, with pumice lapilli as much a =
- , _ .2 —l3 V ' o
17 “0+0 ) v \/ as 2 cm in diameter. Ash flow tuffl?) as .3
0 a 5 3
3: §-
3 o
p.

I Menkinen, 1972
1 G. H. Curtis, oral commun., 1971

3 Age inferred on basis of correlation with
chemically similar Lawlor Tuff, dated at
4.0 t 0.2 m.y.

FIGURE 2,—Stratigraphic section exposed along Monticello Road, southeastern part of Sonoma volcanic field (locs. 17, 45—51).

ANALYTICAL METHODS

SW

 

Older

Dacite
tuffs

Pumice flows

breccia
:‘ n ’

   

Young tuffs

  
   

St. Helena Rhyolite
Member of Sonoma
Volcanics

Oldest NE

Tuff WIth tuff

scoria bombs

      
  

 
 

 

 

 

 

4.0 1 0.23 3.8 t 0.12
METRES FEET
1000 a-
o 1/2 1 MILE 150°
L I l |
I I I n -1000
0 .5 1 KILOMETRE 500 -
— 500
0 «— 0

FIGURE 3,—Structure along a section roughly parallel to Monticello Road (sample locs. 17, 45—51), southeastern part of Sonoma vol-
canic field. Stratigraphic relations between monoclinal section in southwest and St. Helena Rhyolite Member of Sonoma
Volcanics in northeast are not clear, but the St. Helena appears to be youngest unit in section.

of the field. However, a small area of tuff is exposed at
Cobb Mountain and near Siegler Canyon in the Lower
Lake quadrangle (Brice, 1953). At the Siegler Canyon
locality, the tuff is a poorly vesiculated pumice breccia
forming part of the late Pliocene Cache Formation of
Anderson (1936).

SOUTHERN CASCADE RANGE VOLCANIC FIELD

The large volcanic field in the vicinity of Mount Las-
sen, northeast of Sacramento Valley (inset map, fig. 1),
has been active throughout late Cenozoic time, from at
least the late Pliocene to Holocene time (Macdonald,
1966). Tephra from some of the more explosive erup-
tions, such as the Nomlaki Tuff Member 'of the Tehama
Formation, was depoSited in northeastern and north-
western Great Valley (Russell, 1931; Anderson and
Russell, 1939). Although the southern Cascade Range
in the vicinity of Mount Lassen is approximately 320
km to the northeast of the main study area, it is a
potential source area for some of the water-transported
tuffs in the central Coast Ranges because this area has
drained through the San Francisco Bay area since at
least Pleistocene time (Hall, 1966; this study).

All tuff units examined in this study are listed in
table 1. A more detailed discussion of the texture, stra-
tigraphy, and structure of the tuffs and the strati-
graphic sections is given in the description of units.
Basic data on radiometric age determinations for this
study are given in table 2.

ANALYTICAL METHODS

Samples of tuff were collected both laterally and ver-
tically in a stratigraphic section wherever possible to
test for random and systematic variations within each
unit. Between 200 and 500 grams of sample were taken
for physical and chemical analysis. In addition, larger
samples, up to several kilograms, were taken at sev-
eral localities for radiometric dating. Laboratory work
consisted of five main operations: (1) physical descrip-
tion of the tuffs on the basis of microscopic examina-

 

tion, (2) measurement of the refractive indices of glass,
(3) mafic-mineral analysis, (4) X-ray fluorescence spec-
trometric analysis for minor and trace elements, and
(5) radiometric dating of the tuffs.

REF RACTIVE INDICES OF GLASS

The range of refractive indices for several samples of
each tuff were measured under the petrographic mi-
croscope after the samples were treated with 8 percent
hydrofluoric acid to remove altered and hydrated sur-
faces. The Becke line method, a D-line filter, and Car-
gille immersion liquids calibrated to 0.002 R.I. inter-
vals were used in determinations, and the ranges of
refractive indices were corrected for temperature vari-
ations. Precision attained for the average refractive
index of glass in the sample was $0.001.

MAFIC-MINERAL ANALYSIS

Samples were crushed and sieved, and the 120- to
60-mesh fraction (0.125 to 0.250 mm) was separated in
a Frantz magnetic separator. The magnetic fraction
was separated in bromoform, the heavy separate
placed in optic oils, and mafic mineral frequencies were
determined by line count under a petrographic micro-
scope fitted with a mechanical stage.

X-RAY FLUORESCENCE SPECTROMETRIC ANALYSIS

Relative and absolute concentrations of trace- and
minor-element concentrations in tuff samples were de-
termined by means of a Norelco Universal Vacuum
Spectrograph using the analytical procedures de-
scribed by Jack and Carmichael (1968; see table 3).
Samples were analyzed for iron, titanium, barium,
manganese, zirconium, rubidium, strontium, zinc, yt-
trium, gallium, niobium, copper, and nickel. Two types
of analyses were run: (1) rapid-scan analyses of acid-
treated whole-rock samples, which indicate relative
proportions of the rubidium-niobium group (rubidium,
strontium, yttrium, niobium) on the basis of relative

6 CORRELATION 0F LATE CENOZOIC TUFFS, COAST RANGES, CALIFORNIA

peak intensities (Jack and Carmichael, 1968) and (2)
“absolute” analyses of glass separated from the whole-
rock sample, which indicate concentrations of all ele-
ments listed above by comparison with analyzed
standards. Powdered whole-rock samples for rapid
scan were treated with 10 percent hydrochloric acid in
order to remove strontium in carbonate form, a com-
mon groundwater contaminant (Sarna-Wojcicki,
1971).

Rapid-scan analyses can be useful in indicating the
correlation between specific units. However, when con-
sidering a large number of units within a single pet-
rographic province, such as those erupted from the
Sonoma volcanic field, chemical similarities between
units often result in overlap of data for sample groups
from different tuff units. Variations in ground-water
and detrital contamination and in concentrations of
crystals and lithic fragments may cause a spread or

 

scatter of the data, again resulting in apparently over-
lapping sample groups. In either case, the results make
correlation on a fine scale difficult or impossible. In
such situations a procedure that has better resolution
than rapid scanning of whole-rock samples is neces-
sary. For this reason, volcanic glass of selected samples
was separated and scanned to see if the spread of data
for individual units could be reduced.

Selected samples were crushed and sieved, and glass
from the 120- to 60-mesh fraction (0.125 to 0.250 mm)
was separated using the Frantz magnetic separator.
The glass was treated with 10 percent hydrochloric
acid, etched with 5 percent hydrofluoric acid, and
cleaned in an ultrasonic vibrator to remove adhering
fine particles.

The magnetic properties of some samples prevented
complete separation of the salic minerals and altered-
glass fragments from the clean glass. Some of these

TABLE 1.——U nits studied
[See figure 1 for locations of samples]

 

 

   

 

 

    

 
  
    
 
  
 
   
   
   

 

 

 

 

Sample Radiometric age
locality Material Unit Geologic age (K-Ar), in my. References
1 Water- laid tufl‘ ,,,,,,,,,,,, Merced Formation (type section) 1. Late Plioceone and early Pleistocene 1. 49:0. 75 ,W, Hall (1966).
2 do ______________ Alameda Formation ________________________________________________________________________ do
3. 4 ,,,,,,,,,,,,,, Santa Clara Formation. Pliocene and Pleistocene Dibblee (1966)
5 Ash- fall(d?) tuff ____________ Tassajara Formation _____ Pliocene or Pleistocene __ Clark (1943).
6 Water-laid tuff ____________ Ohlson Ranch Formation _ _ Pliocene(?) ____________ Bartow, (oral commun., 1972).
7 Ash-flow tuff ____________ Unnamed formation ______________ Pleistocene ,,,,,,,,,,,,,,,,,,,,,, Wilson (1961); Gilbert (1969)"
Curtis (oral commun., 1971).*
8—11 do ______________ Nomlaki Tuff Member Late Pliocene ____________________ Anderson and Russel (1939);
of Tehama Formation. Evernden, Savage, Curtis,
and James (1964):“
12—15 Water-laid tufi" ____________ Putah Tuff Member of do ______________________ Miller (1966)*; Sims and
Tehama Formation. Sarna-Wojcicki (1974).
16 Ash.tufi” __________________ Sonoma Volcanics __________________________ do ________________ Present study.
17 Ash-flow tuff Sonoma Volcanics 11- Weaver ($949).
18 0.
19—21 Ash-flow tuffs __ . Do.
22—28 do 620.16 ____ Patten (1947); present study.*
29, 30 do 1 _ 4.00:1.00 ____ Clark. (1943); present study.*
31, 32 Water- laid tuf‘f" Livermore Gravels 4.46:0.45 ___. Huey. (1948); present study.*
of Clark (1930)
33, 34 do r" ____________ do ______________________________________________________________________ Do.
35-37 do Merced(?) Formation _ 5 68.0. 68 ,5” Travis (1952); present study.
38—40 Various types of do _________________________ , ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 6.- ______ Travis (1952); Bartow, Sarna- Wojcicki,
tuff. Addicott, and Lajoie (1973). *
41, 42 Water-laid tufi” ,,,,,,,,,,,, Petaluma Formation ,,,,,,,,,,,,,, Early or middle and late Pliocene __________________ Bartow, Sarna-Wojcicki, Addicott
and Lajoie (1973).
43 do ,,,,,,,,,,,,,, Tassajara Formation or ______________ Pliocene or Pleistocene ____________________________ Clark (1943).
Green Valley Formation.
44 do ______________ Unnamed tuff ____________________ Miocene or Pliocene ,,,,,,,,,,,,,, 8.18:2.0 111111 Curtis (oral commun., 1971))“
45—49 Tuff ,,,,,,,,,,,,,,,,,,,,,, Sonoma Volcanics ________________ Middle or Upper Pliocene __________ ‘3.79:0.08 “A. Weaver (1947); Curtis
(oral commun., 1971)*
50, 51 Tuff with scoria bombs ______________ do ________________________________ do ______________________ 253610.16 ,"1 Do.
52, 52A—C Tu ff ,,,,,,,,,,,,,,,,,,,,,, Pinole Tuff ______________________ Middle Pliocene ,,,,,,,,,,,,,,,,,, a5,210.1 ...... Weaver (1947); Evernden, Savage,
Curtis, and James (1964)“
53, 54 Tuff with scoria bombs ______________ do ________________________________ do ,,,,,,,,,,,,,,,,,,,,,, Do.
55—62, 79 Tu if ______________________________ do ________________________________ do _ Do.
63, 63A—C do ,,,,,,,,,,,,,, Tassajara or ________ do ________________________ Do._
Green Valley Formation
of Clark o(1943).
64 do ________________________________________________________ do _ Do.
65, 66 do ,,,,,,,, Green Valley Formation Pliocene ,,,,, Do.
of Clark (1943)
67 do _ Tassajara Formation ______________ Pliocene or Pleistocene ____________ Do.
68 Vent breccia. Unnamed breccia .n Pliocene(?) ,,,,,,,,,,,, Travis (1952),
69 Pumice at Nap Sonoma Volcanics ________________ Pliocene __________________________ Weaver (1949); Jack and
Glass Mountain. Carmichael (1968).
70 Obsidian at Napa do __________________________ 1,"-.. do ______________________ Do.
Glass Mountain.
71 Pumice breccia __________ Cache Formation of Upper Pliocene ,,,,,,,,,,,,,,,,,, Brice (1953).
Anderson (1936)
77 Ash-fem?) tuft ____________ Unnamed tuif ____________________ Pliocene(?) ________________________ Patten (1947).
78 Ash-flow(?) tuff __________ Sonoma Volcanics ________________ Pliocene __________________________ Weaver (1947).

 

*Reference to radiometric age date.
lAt top of unit.

2At base of unit.

“Near base of unit.

METHODS OF EVALUATING CHEMICAL DATA 7

samples were separated in bromoform-alcohol mix-
tures, but the use of heavy liquids was generally
avoided in order to avoid contamination with bromine,
which affects the rubidium analyses in the X-ray
fluorescence procedure.

The separated glass was then mixed with 20 percent
by weight fibrous cellulose binder and pressed into
3.2-cm-diameter discs in a hydraulic press at pressures
of about 2,500 kg/cm2 (35,000 lb/in2). The standards
were similarly prepared in order to provide uniform
surfaces for both sample and standard. Glass separates
were then analyzed for “absolute” concentrations of
other elements that cannot be easily analyzed by the
rapid-scan technique: iron, titanium, barium, man-
ganese, zinc, copper, nickel, and gallium, as well as the
rubidium-niobium group. The position for each of these
elements was calibrated with pure element standards
(for example, RbCl for rubidium), and element con-
centrations were determined by fixed-time counts at
fixed 20 positions. Additional counts were made at ad-
joining 26 positions to determine the shape and inten-

sity of the background curve. U.S. Geological Survey
standards used were G—1 and G2 for all elements ex-
cept for gallium, zinc, copper, and nickel, for which
W—l was used (Fleisher, 1969; Flanagan, 1969).

METHODS OF EVALUATING
CHEMICAL DATA

Trace- and minor-element analyses were compared
(1) graphically, utilizing binary and ternary diagrams
and histograms, (2) by calculation of similarity coeffi-
cients, using a computer program to perform analyses
of similarity, and (3) by cluster analysis, using a com-
puter program to calculate Q-mode cluster analysis on
distance function, and shown on a dendrogram.

GRAPHIC METHODS

Rapid-scan analyses of whole-rock samples for the
three most abundant elements in the rubidium-

 

niobium group (rubidium, strontium, and zirconium)

TABLE 2.—Analytical data on potassium-argon dates
[Age determinations were made at the potassium-argon laboratory of the Department of Geology and Geophysics, University of California, Berkeley. Spectrometric analyses by
N, Gilbert. Potassium analyses by J. Hempel]

 

 

 

 

 

Sample Sample 40 Ar atm. Age
loc. no. Unit Material (percent) (percent) (million years)
22 KA2310 Lawlor Tufl‘, Contra Costa Co. Coarse plagioclase crystals 0.7225 75.0 3.96:0.16
(24—48 mesh)
30 KA2319 Tuff in Tassajara Formation, Plagioclase crystals 0.6060 96.0 4.00: 1.00
south of Mount Diablo, Con- (60—120 mesh)
tra Costa Co.
31 KA2323 Lower tuff bed in Livermore Plagioclase crystals 0.6030 89.9 4.46:0.45
Gravels of Clark (1930) south (60—120 mesh)
of Livermore, Alameda Co.
37 KA2321 Tuff in the Merced(?) Formation Coarse plagioclase crystals 0.7642 92.1 5.68:0.68
near Roblar, Sonoma Co. (24-48 mesh)
TABLE 3.—Summary of X—ray fluorescence spectrometer analytical conditions
[Standard value of iron in percent; all other values in ppm. Modified in part from Jack and Carmichael (1968)]
Exciting Primary Detector Standard (assumed value)
Analytical Analyzing radiation beam (with pulse-height weight percent or
Element line crystal (50 kilovolts) filter discrimination) Path parts per million
LiF 200 W ________ Scintillation ____________ Air ________ G—2 (1.844)
LiF 200 W ________ Flow-proportional ________ Vacuum ____ G—l (1560); G2 (2930)
LiF 200 W _________ Scintillation ____________ Air ________ G—l (200); G-2 (280)
LiF 200 W ________ Flow-proportional ________ Vacuum ____ G-l (1040); G—2 (2030)
LiF 200 Mo 0.001”Ti Scintillation ____________ Air ________ W—l (78)
LiF 200 Mo 0.001"Ti ____________ do __________________ do____ W—l (110)
LiF 200 Mo 0.001”Ti ____________ do __________________ do_-__ W—l (82)
LiF 200 Mo 0.001”Ti ____________ do __________________ do____ W—l (16)
LiF 220 W ____________________ do __________________ do ___ G-l (220); G—2 (175)
LiF 220 W ____________________ do ___________________ do_-__ G—l (250); G—2 (465)
LiF 220 W ____________________ do __________________ do___- G—l (13); G—2 (10)
LiF 220 W ________ ‘ ____________ do __________________ do____ G—l (210); G~2 (320)
LiF 220 W ____________________ do __________________ do__-_ G—l (20); G2 (16)

 

 

‘Jack and Carmichael (1968).

8 CORRELATION OF LATE CENOZOIC TUFFS, COAST RANGES, CALIFORNIA

were recalculated to mutual percentages and plotted
on a ternary diagram. Analyses of absolute concentra—
tions of trace and minor elements in the purified glass
were plotted on histograms and on binary diagrams of
one element plotted against another.

SIMILARITY COEFFICIENT

A coefficient that allows all analyzed variables for a
pair of samples to be compared has been derived by
Borchardt, Aruscavage, and Millard (1972). This simi-
larity coefficient, which is 1 for identical analyses, is
given by:

M:

R.-
dm) =" 1,. , (1)

 

where

d(A,B) = d(B,A) = similarity coefficient for compari—
son between sample A and sample B,

i = element number,

n = number of elements

Ri = XiA/XiB iinBBXiA; otherwise XiB/XiA,

XiA = concentration of element i in sample A,
and

XiB = concentration of element i in sample B.

The similarity coefficient is a simple and effective
way of comparing any quantitative parameters for any
group of samples, and the method is readily adapted to
a simple computer program. The only disadvantage to
this method involves comparison of a large number of
samples. For 50 samples, 1,225 comparisons must be
made; for 100, 4,950, and for 200, 19,900 since the
number of comparisons increases exponentially with
increase of the sample population. For large sample
populations, provisions must be made to extract coeffi-
cients within a selected range.

Borchardt, Aruscavage, and Millard (1972) have also
introduced weighting coefficients in order to minimize
the effect of the least accurately determined elements
on the similarity coefficients. In this study, weighting
coefficients were not used. Instead, only those elements
were used that were considered reliable, both with re-
spect to the precision of the analysis and the natural
variability of the elements within the volcanic glass.
The reliability of any particular element was
evaluated by multiple analyses of samples from a
single, extensive tuff bed (locs. 22—28). Analyses were
made on samples collected both laterally and vertically
in the section in order to test the internal consistency
of chemical and physical properties within a single dep-
ositional unit. Analyses for only those elements that
showed a high degree of consistency (iron, titanium,
barium, manganese, zirconium, rubidium, strontium,

 

and zinc) were used in calculating similarity coeffi-
cients and the cluster analysis described in the next
section. Comparisons of multiple analyses of a single
unit indicated that copper, nickel, gallium, and, to a
lesser extent, yttrium were not reliable for correlation
purposes, mainly because these elements occur in low
concentrations not much above the detection limit of
the X-ray fluorescence method. Consequently, the pre-
cision for analyses of these elements was low and these
elements were not included in the comparison proce-
dure. In addition, strontium, though abundant, varies
greatly owing to ground-water contamination, con-
centration in feldspar and mafic microlites and
phenocrysts, and concentration in mafic and inter-
mediate lithic volcanic fragments. However, strontium
is important in distinguishing between tuffs derived
from different volcanic fields, so analyses of similarity
were run both with and without strontium.

CLUSTER ANALYSIS

In addition to calculation of similarity coefficients,
the chemical data were also compared by means of
Q-mode cluster analysis using a computer program by
Parks (1970). According to Parks, the program “com-
putes an R-mode principal components analysis (factor
analysis with unities in the principal diagonal)* * *”
using the simple distance function. Factor scores are
then calculated, forming a set of “new orthogonal (un-
correlated) variables.”1 The formula used for the sim-
ple distance function for R-mode analysis is

d1,2=1.O—[

Using the new orthogonal variables, the program
“computes a Q-mode similarity matrix, comparing
each sample with all other samples across all vari-
ables,” using the distance function as similarity coeffi-
cient. The formula for distance function for Q-mode
analysis is

N 2 1/2
2 (X1 i—le.) W] .

i:1

M 1/2
d1,2= [ Z (Xi 1 ‘Xi 2)2/M] -
i=1

The Q-mode similarity matrix now contains the eu-
clidian distance between all possible pairs of samples
measured in a space with dimensionality equivalent to
the number of factors found in the R-mode principal
components analysis. This matrix is then searched for
the two samples with the least distance between them,
which are then combined to form a cluster and the
measurements of the pair averaged. All distances be-

lSome of the elements analyzed in this study, for instance, iron and manganese, are not
independent variables but, on the contrary, show a high degree of correlation for certain
sample groups (see fig. 7).

RESULTS OF ANALYSES 9

tween either member of the pair and other samples are
recalculated using the newly averaged measurements
of the cluster. The process is repeated until all the
samples are grouped into a number of clusters of prog-
ressively greater distance (higher values of the dis-
tance function). The program plots all the groups on a
dendrogram that shows the relations of all individual
samples and all groups of samples to each other, with
respect to the distance function.

The advantage of this method is that several orders
of chemical variability and relations between samples
are readily apparent in a two-dimensional format.
Since the outcome of the clustering procedure is influ-
enced by the composition of every sample present in
the sample group, the actual values of the distance
function and the resulting clusters formed are affected
by the range of compositional types included in the
comparison. Inclusion of particularly unusual compo-
sional varieties in the cluster analysis results in
tighter clustering (smaller values of the distance func-
tion) for samples of similar composition, while exclu-
sion of such unusual varieties results in a greater
spread (higher values of the distance function) between
the remaining samples. Inclusion or exclusion of the
unusual compositional varieties serves as a device
with which to focus on compositional variations be-
tween sample groups of particular interest.

RESULTS OF ANALYSES

Before individual tuff units can be correlated by
means of trace- and minor-element chemistry, the var-
iability within and between individual eruptive units2
and within and between individual volcanic fields
must be established. Greatest differences in trace- and
minor-element chemistry were observed between
silicic tuffs on the one hand and intermediate pumice-
lapilli tuffs on the other. These differences are illus-
trated by the two analyses shown in table 4. The group
average similarity coefficients between silicic and in-
termediate tuff groups range between 0.42 and 0.61,
with an overall average of 0.51, the lowest average
coefficient for all sample groups considered (fig. 4).
Large differences between the silicic and intermediate
tephra are also indicated by the dendrogram derived
from cluster analysis (fig. 5). Silicic and intermediate
samples are grouped at highest values of the distance
function (0.25—0.48).

Among silicic tuffs, greatest differences are observed
between tuffs derived from different volcanic fields.
Tuffs that are definitely known to have been erupted in

2An eruptive unit is defined here as a collection of all those outcrops that, on the basis of
several criteria, primarily trace- and minor-element chemistry of the volcanic glass but also
petrographic characteristics, radiometric age, stratigraphic position, fossil data, and other
pertinent information, are considered to be products of a single eruption or of multiple
eruptions closely spaced in time.

 

TABLE 4.—Comparison of glass compositions of a silicic and an
intermediate tuff
[Concentrations of iron and silica, in percent; all other concentrations in parts million]

 

 

SiOz Fe0+ Fe203 Ti Ba Mn Zr Rb
Sample 501 .......... 62.70 6.86 7362 428 1596 207 54
Sample 372 __________ 71.43 1.62 803 698 237 247 181

 

‘Intermediate tuff with scoria bombs.
2Silicic tufl‘.

the southern Cascade Range, such as the Nomlaki Tuff
Member of the Tehama Formation (Anderson and Rus-
sell, 1939; Lydon, 1967) and a pumiceous tuff near
Mineral (Wilson, 1961; Gilbert, 1969), have higher
concentrations of strontium and lower concentrations
of iron, zirconium, zinc, and yttrium than tuffs erupted
in the Sonoma volcanic field (table 5). The samples of
pumice tuff near Mineral (fig. 1, loo. 7) and the Nom-
laki Tuff Member (fig. 1, locs. 8—11) have low similarity
coefficients when compared with silicic tuffs erupted
from the Sonoma volcanic field (fig. 4). Group average
similarity coefficients comparing tuffs from the south-
ern Cascade Range and the Sonoma volcanic field
range from 0.48 to 0.64, with an overall average of
0.60. Tuffs from different volcanic provinces have dis-
tance function values of between 0.135 and 0.210 (fig.
5). Differences between tuffs derived from the Sonoma
volcanic field, those from the southern Cascade Range,
and those of inferred southern Cascade Range prove-
nance are graphically illustrated in figures 6 and 7.
Silicic tuffs of different ages that are known to have
been erupted from the same volcanic field show smaller
compositional differences than those erupted from dif-
ferent volcanic fields. Age and source criteria inde-
pendent of chemical analyses are available to test the
validity of this assertion. Relative and absolute ages of
many of the units studied are known from stratigraph-
ic position and radiometric dates. With respect to
source, it is possible to identify those tuffs that were
erupted, for example, from the Sonoma volcanic field
by several criteria. First, coarse tuffs, tuff-breccias,
and agglomerates are interbedded with flow rocks in
the Sonoma volcanic field itself, indicating proximity
of the tuffs to vents. For instance, north of Suisun Bay
(fig. 1, locs. 19—2 1) pumice bombs as much as 30 cm in
diameter were found in coarse ash flow tuffs. Second, in
outlying areas beyond the Sonoma volcanic field, the
source of the more widespread silicic tuffs is indicated
by coarseness of the tuffs and by size gradients that
increase towards the Sonoma volcanic field. Independ-
ent confirmation of the source of these tuffs is obtained
from the trace- and minor-element analyses of the vol-
canic glass. Most analyses of tuffs in the central Coast
Ranges show strong chemical similarities between
tuffs of the Sonoma volcanic field and those of the out-

10 CORRELATION OF LATE CENOZOIC TUFFS, COAST RANGES, CALIFORNIA

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Formation of Ander-

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Lake area

FIGURE 4.——Similarity coefficient matrix. Similarity coefficients are calculated for each sample pair in study group. Individual values of

similarity coefficients are given in lower left half of matrix, while average values for main sample groups are given in symmetric
positions across the identity diagonal in upper right half of matrix. Calculations were made by comparison of following eight elements:
Fe, Ti, Ba, Mn, Zr, Sr, Rb and Zn. No iron analyses were available for samples 1 and 2; consequently these samples were compared
with other samples using remaining seven elements. Values of similarity coefficient are given in hundredths, with decimal point
omitted.

lying areas, including specific correlatives (fig. 1, locs. distance function are between 0.05 and 0.135.

17—34, 47, and 55). Similarity coefficients for silicic Smaller differences in chemical composition of vol-
tuffs erupted in the Sonoma volcanic field range from canic glass are observed between samples of the same
0.66 to 0.85, with an average of 0.75, and values of the , tuff unit. The similarity coefficient for seven samples of

RESULTS OF ANALYSES 11

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the Lawlor Tuff, for example, range from 0.91 to 0.97
with an average of 0.95. Values of the distance func-
tion for samples within the Lawlor Tuff range between
0.015 and 0.050. Values of the distance function for
duplicate analyses of single samples and on replicate
analyses of samples from single exposures are in the
lower part of this range (for example, locs. 3 and 4, 33
and 34, 65 and 66, fig. 1).

Graphic analysis of the chemical data was usually

sufficient to distinguish between most eruptive units
because variations in chemical composition within
units were considerably smaller than variations be-
tween units. However, in a few instances, for example,
the Putah Tuff Member of the Tehama Formation and
the tuff in the Merced(?) Formation of Sonoma County,
differences between tuffs erupted from a single vol-
canic province were rather subtle and could be resolved
only by statistical comparison of analyses.

CORRELATION 0F LATE CENOZOIC TUFFS, COAST RANGES, CALIFORNIA

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RESULTS OF ANALYSES 13

TABLE 5.—Chemical analyses and petrographic data

[Sample numbers are same as locality numbers shown in figure 1. ND, not determined. Concentration of iron in precent; all other concentrations in parts per

million. P, mineral present but not abundant]

 

 

 

 

 

 

 

a . , Concentrations of minor and trace elements in volcanic glass Main refractive Principal mafic mineral frequencies (percent) Rock
N°' Fe Ti Ba Mn Zr Rb Sr Zn Y Ga Nb Cu Ni Index °f glass Gr. hblde Br. hblde Hypersth. Augite type
Fine-grained tuffs in Coast Ranges derived from the southern Cascade Range

ND 1,628 1,166 395 107 125 130 26 ND 13 4 35 7 149910001 ‘72 10 ‘28 I0 Tuff

ND 1,867 1,130 377 111 120 131 34 ND 12 9 21 4O 1499:0001 80 0 20 0 Do.

281 102 115 113 25 9 13 13 39 13 ND 77 0 21 2 Do.

260 105 123 131 27 9 12 12 15 7 ND ND ND ND ND Do.

287 125 199 106 25 12 13 7 22 11 1.49910001 90 2 0 8 Do.

305 109 166 201 23 15 8 36 15 15 ND 96 0 3 1 Do.

 

 

Ash-flow tuffs near Mount Lassen and northern Great Valley, erupted from the southern Cascade Range (Nomlaki Tuff, 8—11)

 

 

 

 

 

 

 

 

 

7 .61 885 790 327 104 79 414 18 9 14 33 6 1 1.496_1.500:0.001 I48 10 152 I0 Tuff.
8 .90 1,372 1,052 518 169 102 177 28 9 12 30 9 10 1.500_1.501:0.001 24 0 68 8 Do.
9 .94 1,332 1,055 419 182 107 169 33 12 14 35 43 12 1501:0001 15 13 60 13 Do.
10 .87 1,168 965 387 181 103 162 28 14 13 4 10 7 1501:0001 26 8 55 10 Do.
11 “.108 1,453 1,003 420 161 99 168 32 9 13 20 11 12 1.501—1.502:0001 30 6 51 13 Do.
Tuffs erupted in the Sonoma volcanic field, or of inferred Sonoma volcanic prowenance, central Coast Ranges
(Putah Tuff Member, 12—15, and correlative, 16)
12 11.436 1,251 814 278 276 153 27 45 28 13 3 14 15 1503:0001 0 3 91 6 Tot)“.
13 .,._1.34 1,088 794 262 256 174 35 43 27 13 14 20 14 1502:0001 0 3 93 4 Do.
14 ____1.39 1,018 838 244 261 170 37 39 21 14 0 15 9 1501:0001 0 1 93 6 Do.
15 ___-1.40 1,131 981 244 263 158 68 37 24 13 0 12 8 1503:0001 0 1 98 1 Do.
16 ____1.44 1,006 875 247 274 186 38 41 17 16 7 17 10 1.502_1.503:0.001 1 4 85 10 Do.
Tuff erupted in the Sonoma volcanic field, or of inferred Sonoma volcanic provenance, central Coast Ranges
(Lawlor Tuff, 22—28, and correlative tuffs, l7—21, 29—34)
17 -_.-1.62 1,074 836 366 312 154 51 60 47 17 24 27 15 1506:0001 ND ND ND ND Tun”.
18 --__1.60 1,064 711 441 301 140 64 60 34 15 13 0 10 ND 0 98 2 0 Do.
19 --._1.73 1,174 817 459 326 154 59 58 26 19 18 12 11 1504:0001 ND ND ND ND Do.
20 --_-1.62 1,283 840 448 336 157 56 57 24 18 20 5 10 1505:0001 20 211 278 211 Do
3 Cl 3 3
21 “11.75 1,473 801 436 339 143 68 59 27 18 15 9 11 1.508; 1512:0001 N8 N53 Ni; N3 D0
22 ____1.72 1,174 758 433 301 148 58 54 26 16 25 8 9 ND ND ND ND ND Do'
23 __-_1.72 1,211 812 440 297 145 50 57 24 17 13 9 10 1505:0001 3 64 4 29 Do.
24 ____1.68 1,048 755 428 303 147 48 59 25 17 15 14 11 1505:0001 0 52 8 40 Do'
25 "1.1.81 1,180 796 470 304 149 62 63 25 20 16 16 12 1505:0001 ND ND ND ND DO'
26 ____1.78 1,203 845 447 326 152 62 56 25 17 23 2 9 1505:0001 7 49 6 39 DO‘
27 ___-1.73 1,173 830 437 329 143 54 59 18 18 18 7 15 ND ND ND ND ND DO'
28 ____1.72 1,129 768 454 319 146 57 56 18 17 15 4 8 ND 0 73 6 21 DO'
29 “-1168 1,258 913 456 313 144 71 67 32 22 3 18 11 41.504; 1506:0001 28 22 0 50 Do'
30 _.__1.83 1,183 849 449 304 148 53 61 24 17 14 4 10 41.500; 1506:0001 ,0 535 527 538 Do.
54 359 521 516 D0.
31 ___-1.70 1,134 809 422 305 148 71 59 29 17 14 9 12 41.503; 1505:0001 0 23 56 21 Do
32 ____1.75 1.213 733 431 297 143 60 58 25 17 16 11 13 41.499; 1505:0001 0 39 29 32 DO‘
33 ____1.82 1,136 684 502 306 135 74 60 23 14 21 13 11 1505: 001 0 23 52 24 Do.
34 ____1.82 1,137 718 517 290 137 82 56 24 13 9 8 8 ' ' ‘
Tuffs erupted in the Sonoma volcanic field, or of inferred Sonoma volcanic provenance, central Coast Ranges
(tuff in the Merced(?) Formation of Sonoma County, 35—40, and correlatives, 41—44)
35 --__1.18 876 686 237 247 181 41 40 24 17 17 11 12 1.498; 1501:0001 2 96 1 0 Tun“.
36 -_-_1.18 803 698 233 242 176 39 43 21 19 7 11 14 1.498; 1501:0001 ND ND ND ND Do.
60 61 6'70 629
37 -___1.21 710 759 250 216 174 40 40 19 15 3 13 12 1502:0001 { 71 712 757 766} Do.
50 529 530 513
38 _-__1.13 766 817 259 225 190 28 44 28 18 9 43 20 ND ND ND ND ND Do
39 ___11.09 750 751 310 249 179 27 44 24 19 4 11 8 ND ND ND ND ND Do
40 ___-1.11 755 755 285 228 183 27 48 28 18 9 6 6 ND ND ND ND ND Do
41 ___-1.07 729 724 278 221 181 44 41 23 15 17 34 13 ND 51 53 536 560 Do
42 -1__1.16 775 767 215 219 177 29 48 29 14 9 23 10 ND a0 91 s95 84 Do.
43 __-_1.16 738 667 240 261 179 59 39 20 14 10 1 11 1503:0001 10 11 36 43 Do.
44 1___1.27 857 654 250 279 163 39 46 41 18 8 15 14 1.501; 1503:0001 7 17 57 18 Do.
Tuffs and flows of the Sonoma Volcanics, Monticello Road section
45 .-__0.58 1,105 897 26 402 214 64 75 46 17 51 30 12 ND 9? 0 0 0 Welded
tuff(?).
46 ____1.36 1,348 817 266 333 190 29 51 35 14 46 15 17 ND ‘0 0 0 ~ 0 Tuff.
47 ____2.70 1,369 585 751 447 94 50 107 24 25 79 16 16 1515:0001 9P P P 0 Pumice
breccia.
48 ____1.05 818 625 97 418 152 22 33 24 22 73 18 6 1507:0001 9P 0 0 0 Deficits
ow.
49 ____2.08 1,178 694 576 530 132 20 113 46 23 49 23 10 1513:0001 “P 0 0 P Tuff.
50 _-__5.12 7,362 423 1,596 207 54 208 114 22 22 33 34 14 1565:0005 91 0 3 96 Do.
51 ,__-2.78 3,299 657 784 342 93 151 88 31 24 42 26 18 1511:0001 9.103 3 86 7 Do.

 

In summary, graphic and statistical evaluation of ity exist in trace- and minor-element compositions of
the chemical data indicates that four orders of variabil- volcanic glass. The greatest variability exists between

14

CORRELATION OF LATE CENOZOIC TUFFS, COAST RANGES, CALIFORNIA

TABLE 5.—Chemical analyses and petrographic data—Continued

 

Concentrations of minor and trace elements in volcanic glass

 

Principal mafic mineral frequencies (percent)

 

 

 

 

 

 

 

 

 

 

 

 

 

Sample Main refractive Rock
°‘ Fe Ti Ba Mn Zr Rb Sr Zn Y Ga Nb Cu Ni Index “81855 Gr. hblde Br. hblde Hypersth. Augite We
Tuffs erupted in the Sonoma volcanic field or of inferred Sonoma volcanic provenance, central Coast Ranges
(tuffs of the Pinole Tuff and correlative sample, 63)
52 ___1.20 1,014 584 236 230 160 55 37 26 16 17 9 11 1501:0001 H7 77 12 4 Tuff.
53 ""348 4.596 444 855 238 69 262 60 30 16 14 5 4 1533101001 “0 4 34 62 A9810-
merate
tufl‘.
54 -.__3.15 3,935 435 781 307 90 191 58 26 16 21 9 ‘5 a1509,1513; n0 0 31 70 Tun.
1528:0001
55 ,._,2.70 1,798 413 814 444 107 87 95 61 22 20 17 17 1509:0001 0 77 0 23 Do.
1 48 6 46
56 1,112.74 1,621 470 826 456 104 84 97 65 20 21 3 8 1501:0001 0 25 15 60 Do.
57 “1.147 1,615 529 232 244 151 69 33 16 17 12 5 5 1501:0001 0 16 73 11 Do.
58 “1.150 1,206 587 330 328 136 64 44 19 18 7 11 11 1502:0001 ND ND ND ND Do
59 111.230 2,308 743 616 405 108 107 70 54 18 17 8 3 1506:0001 x0.120 P 0 P Do
60 ".1299 4,663 1,135 643 381 87 156 83 25 17 23 10 8 1509:0001 100 0 P P Do
61 _,,.2.82 4,890 439 598 272 82 266 49 16 15 15 10 8 130 0 3 97 Do
0 5 30 64
62 __,13.63 3,624 498 983 371 88 118 89 20 20 14 9 15 nigpgfijgifi; 0 0 46 55 Do
63 ,___1.12 1,146 582 267 218 171 44 34 28 13 14 22 12 ND 4 7 6 83
140 145 148 1487 D0
157 159 155 1579
Uncorrelated tuffs of the Tassajara area, south of Mount Diablo
64 "1.1.25 989 686 250 306 172 44 40 32 16 23 6 10 31.501; 1502:0001 1 21 22 57 Do.
6516 __1.28 1,316 601 276 247 152 78 26 15 14 8 4 7 +0 1 { 0 0 2 98 Do.
66l7 “1.30 1,355 622 270 251 154 82 29 14 15 4 6 13 1-501: ‘00 ND ND ND ND Do.
67 _.__1.95 1,360 908 498 235 40 79 90 26 17 17 7 8 1501:0001 1 32 36 32 Do.
Vent tuff—breccia, 68; associated pumice and obsidian of Napa Glass Mountain, Sonoma County, 69, 70
68 W075 851 651 79 221 192 64 26 22 15 10 18 9 ND ND ND ND ND Vegit 4
reccxa.
69 -,,_1.08 555 447 202 283 199 11 57 30 16 26 8 12 ND 180 0 P 0 Pumice.
70 .___1.08 555 443 211 291 207 6 59 34 16 24 9 14 ND ‘80 0 P 0 Obsid-
lan.
Tuff in the Cache Formation of the Clear Lake area, north-central Coast Ranges
71 ____1.28 919 1,368 269 235 138 209 50 23 15 4 11 8 1503:0001 . 0 0 P 0 Tun“- ‘
breccta.
Altered and chemically contaminated tuff south of Suisun Bay
77 1,111.07 831 808 844 189 148 109 37 14 16 10 18 17
Hydrothermally altered tuff in the Sonoma Volcanics north of St. Helena
78 "No.21 5,400 682 20 526 142 57 3 35 8 44 12 8

 

Tuffaceous lake clays in the Pinole Tuff

 

79 ____1.97 1,167 1,3751,037 166 83 54 124 14 15 8 11 8

 

1Data from Hall (1965).

248—120 mesh.

“120 mesh.

‘More than one glass type in sample.

560—120 mesh.

628—48 mesh.

735—100 mesh.

328—32 mesh.

9Separate consists mostly of magnetite and ilmenite plus a few grains of pink zircon.

tephra of silicic and intermediate compositions. Con-
sidering silicic tephra alone, the greatest chemical var-
iability exists between units erupted from different
volcanic fields. Smaller chemical differences are ob-
served between silicic tuffs erupted at different times
from a single volcanic field, while the smallest varia-
bility is observed within a tuff layer representing a
single eruption. Of the silicic tuffs analyzed, variations

”Very few transparent mafic minerals present.

“Separate contains mostly biotite and ilmenite.

12Mafic mineral separate contains mostly magnetite or ilmenite.
13Mafic mineral separate from scoria lapillus in tuft".

l‘Angular mafic mineral grains.

lsRounded mafic mineral grains.

16Coarse glass separate, 60—120 mesh,

l"Fine glass separate, 120—200 mesh.

l“Dark-green to bluish-green amphibole (arfedsonite?)

in the trace- and minor-element compositions of the
glass are discontinuous from one order to the next,
making it possible in most instances to identify tephra
of individual eruptions, as well as the volcanic field
from which the tephra was erupted.

TUFF CORRELATIONS

Correlations were made on the basis of chemical fin-

TUFF CORRELATIONS

  

 

Sr
EXPLANATION

o
Tuffs of northern Great
Valley, erupted from
southern Cascade Range

Pyroclastic deposits of
central Coast Range
source, erupted mainly
from Sonoma volcanic
field

A
Tuffs in central Coast Range of
inferred Cascade Range provenance

FIGURE 6.—Provincial differences between tuffs in central
Coast Ranges and southern Cascade Range. Mutual per-
centages of net intensity peaks for Rb, Sr, and Zr. Inten-
sity peaks were obtained by using rapid X-ray fluores—
cence scans on powdered whole-rock samples treated with
10 percent HCl. Dashed line separates tuffs of Cascade
Range provenance from those of central Coast Ranges
provenance.

gerprinting of the volcanic glass, supported by addi-
tional evidence such as tuff petrography, stratigraphic
position and sequence, potassium-argon ages, and
available fossil data. Five widespread tuff units have
been recognized within the central Coast Ranges. Fig-
ure 8 shows the known maximum areal distribution of
these units. In order of decreasing age, the tuffs and
their chemical correlatives are: (1) the tuff in the
Merced(?) Formation of Sonoma County (fig. 9, locs.
35—44), (2) the Pinole Tuff and tuffs in the lower part of
the Monticello Road section in the Sonoma volcanic field
(fig. 9, lacs. 47, 50—56, 59—63), (3) the Lawlor Tuff (fig. 9,
locs. 17-34), (4) the Putah Tuff Member of the Tehama
Formation (fig. 9, locs. 12—16), and (5) the tuff in the
type section of the Merced Formation of western San
Francisco peninsula (fig. 9, locs. 1—4). In addition to the
above tuff units, there are approximately twelve more
known tuff units within the central Coast Ranges that
at this time have not been correlated with any wide-
spread eruptive unit.

TUFF IN THE MERCED(?) FORMATION OF SONOMA COUNTY

Exposures of correlative tuff have been found in the
marine Merced(?) Formation of Sonoma County (fig. 1,
locs. 35—40), in the fresh- or brackish-water Petaluma
Formation north of San Pablo Bay (fig. 1, locs. 41 and
42), and near the base of the continental Tassaja‘ra
Formation or the upper part of Clark’s (1943) Green
Valley Formation south of Mount Diablo (fig. 1, 10c. 43).
A tuff that overlies the Neroly Formation and underlies

 

 

 

 

 

15

E 1800 l I I l l
_l
2' 1600— I
2
5 1400— _
fl.
.9
I 1200— -
< ,
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l- A‘

800— . _
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o 1.0 2.0 3.0 . 4.0 5.0
IRON CONTENT, IN PERCENT

EXPLANATION
I
Central Coast Ranges, Sonoma volcanic

field (Monticello Road section)

A
Central Coast Ranges, Pinole tuffs

Central Coast Ranges: Putah Tuff,Lawlor
Tuff, and tuff in Merced (?) Formation
of Sonoma County

0
Southern Cascade Range provenance

0
Central Coast Ranges of probable Cascade
Range provenance

FIGURE 7 .——Provincial differences between tuffs from the central
Coast Ranges and from the southern Cascade Range, as illus-
trated by variations in concentrations of iron and manganese in
volcanic glass.

Ham’s (1952) Mulholland Formation in the eastern
Berkeley Hills (fig. 1, loc. 44) is a tentative correlative.
The tuff in the Merced(?) Formation of Sonoma County
has been dated at 6.1:0.1 m.y. (fig. 1, 10c. 40, Bartow
and others, 1973) and at 5710.5 m.y. (fig. 1, 10c. 37;
table 2), while the tuff in the eastern Berkeley Hills (fig.
1, 10c. 44) has been dated at 82:20 my (G. H. Curtis,
oral commun., 1971); consequently, its correlation with
the tuff in the Merced(?) Formation is uncertain.
Although the refractive indices of the glass are very
similar for those samples examined, the mafic-mineral
frequencies between fine and coarse facies are particu-
larly obvious. For instance, sample 35 (table 5), a fine
water-laid ash tuff, is considerably enriched in
hornblende with respect to sample 37, from a coarser
facies of the same tuff containing pumice lapilli and
cobbles. Presumably, the differences in mafic-mineral
frequencies vary considerably (table 5). Differences in
mafic-mineral frequencies between these samples are
due to hydraulic sorting. Frequency counts of mafic
minerals on three size fractions of the coarser facies of
this tuff indicate that the hornblende is finer grained

16

than augite and therefore would tend to be concen-
trated in the finer grained facies (fig. 10).

PINOLE TUFF

The Pinole Tuff, a 27 5-m-thick sequence of tuffs, con-
tains both silicic tuffs (fig. 1, locs. 52, 57 and 58) as well
as pumice-lapilli tuffs of intermediate composition (ta-
ble 1, locs. 53—56, 59—62). Glass composition of the in-
termediate tuffs is heterogeneous. Pumice lapilli of
several different compositions may be present within a
single sample, as indicated by presence of several glass

CORRELATION OF LATE CENOZOIC TUFFS, COAST RANGES, CALIFORNIA

types with different refractive indices (table 5, locs. 54,
62). This heterogeneity introduces considerable scatter
into the analytical data owing to sampling errors and
makes it difficult to make specific correlations on the
basis of glass chemistry.

The Pinole Tuff can be correlated in a general way
with the lower part of the Sonoma volcanic field in the
Monticello Road section east of Napa. At both localities,
andesitic tuffs containing scoria lapilli and bombs (fig.
9, locs. 50, 51, 53, 54, 60, 61, and 62) are exposed near
the base of the sections. At both sections, volcanic de-

 

 

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FIGURE 8.—Maximum known areal distribution of five major eruptive tuff units (horizontal lined areas) identified in present study.
A, Tuff at type locality of Merced Formation. B, Putah Tuff Member of Tehema Formation. C, Lawlor Tufi'. D, Pinole Tufl‘.

E, Tufl‘ in the Merced(?) Formation of Sonoma County.

TUFF CORRELATIONS

posits grade upwards into more silicic types. Figure 11
shows rapid-scan analyses on whole-rock samples from
both sections. Similarity coefficients for heterogeneous
intermediate tephra from the two localities are low,
probably for the reasons mentioned above. The highest
similarity coefficients for sample pairs from the two
sections range from 80 to 87 (locs. 47, 53, 56, 59—62),
about the same as the highest internal coefficients for
the Pinole Tuff, except for samples from localities 55
and 56, which have a coefficient of 0.96. Intermediate
tuffs from the Pinole and Monticello Road sections of the
Sonoma volcanic field are more similar to each other
than they are to any other analyzed tuff (fig. 4). In
addition, radiometric ages support the correlation of
these tuffs. A potassium-argon date of 5.2: 0.1 m.y. was
obtained on a sample from the Pinole Tuff near the base
of the section (10c. 61) (Evernden and others, 1964),
whereas a 5.4:0.2-m.y. date was obtained on a sample
of tuff with scoria bombs near the base of the Monticello
Road section (10c. 50) in the Sonoma volcanic field (G. H.
Curtis, oral commun., 1971).

Since the pyroclastic rocks in the Monticello Road
section are thicker and generally coarser and contain
interbedded flow rocks and intrusive dikes, we might
suspect that they are closer to the eruptive source than
are the Pinole Tuff (fig. 1, locs. 52—62). The tuff con-
taining the scoria bombs in the Pinole Tuff, however, is
coarser at locality 53 than at the Monticello Road local-
ity 50, suggesting that for this unit at least the erup-
tive vent was closer to the Pinole localities.

Similarities in stratigraphic sequence and glass
chemistry at the Pinole and Monticello Road localities,
as well as radiometric dates, suggest that the sections
are contemporaneous and had a common source. How-
ever, because niobium content in volcanic glass of the
Monticello Road volcanic rocks is systematically
higher (table 5, samples 45—62), it is still possible that
tephra was erupted from a series of separate but re-
lated vents and need not have had a common source.

The Pinole Tuff is correlated in a general way with a
60-m-thick sequence of tuffs and tuffaceous sediments
south of Mount Diablo. Rapid-scan analyses again
show vertically systematic changes in chemical com-
position in both sections (figs. 12 and 13). The similar-
ity coefficient between the only complete “absolute”
analysis made on a sample from the locality south of
Mount Diablo and a tuff in the Pinole Tuff section is
0.91 (locs. 52 and 63). The sample at locality 52, how-
ever, was obtained from near the top of the Pinole Tuff
at Rodeo, while the sample at locality 63 was obtained
from near the base of the section south of Mount Di-
ablo; consequently these tuffs may not be correlative.
Nevertheless, since the tuff at locality 63 is massive,
while that at locality 52 is composed of rounded pumice

 

17

lapilli in a tuffaceous matrix, it is possible that the tuff
at locality 52 was reworked from a more massive unit
lower in the Rodeo section.

LAWLOR TUFF

The known extent of the Lawlor Tuff (fig. 1, locs.
22—30) and its correlatives (fig. 1, locs. 17—21, 29—34) is
shown in figure 8. The Lawlor is an ash flow tuff, the
distant end of which has been found as far south as the
southwestern flank of Mount Diablo (fig. 1, locs. 29,
30), interbedded with the uppermost(?) part of the Tas-
sajara Formation; a reworked, water-laid correlative
has been found even further south on the north flank of
the Diablo Range, south of the town of Livermore,
where it is interbedded with the Livermore Gravels of
Clark (1930) (fig. 1, locs. 31—34). Three outcrops of ash
flow tuff correlative with the Lawlor have also been
found within the upper part of the Sonoma Volcanics
(fig. 1, 100. 17—21).

The average similarity coefficient for analyses of the
Lawlor Tuff and its correlatives is 0.93, while values of
the distance function in cluster analysis range from
0.015 to 0.035 for all but one sample (29) and from
0.015 to 0.060 for all samples (fig. 5). The similarity of
the chemical analyses can be easily visualized when
histograms of the analyses are compared (fig. 14). The
similarity of the analyses becomes even more remark-
able when average values of samples from the physi-
cally continuous Lawlor Tuff are compared with aver-
age values of samples from all other known correlative
but physically separate localities (table 6). Compari-
sons of average values indicate greater consistency in
concentrations even for some of those elements (yt-
trium, gallium, niobium, copper, and nickel) that show
considerable scatter in individual sample comparisons.

Radiometric ages support correlations made on the
basis of chemical fingerprints (fig. 9). A potassium-
argon date of 3.96: 0.16 m.y. has been obtained for the
Lawlor Tuff at its type locality in Lawlor Ravine in the
hills south of Suisun Bay, north of Mount Diablo (fig. 9,
locs. 22, 27, 28), a date of 4.01- 1.0 my on an exposure
in the Tassajara area, south of Mount Diablo (fig. 9,
table 2, 10c. 30), and a date of about 4.46:0.45 m.y.
from its southernmost correlative in the Livermore
Gravels of Clark (1930) (fig. 9, table 2, lacs. 31, 32). The
tuff exposure correlative with the Lawlor Tuff near the
top of the Monticello Road section (fig. 9, 10c. 17) is
overlain by the St. Helena Rhyolite Member of the
Sonoma Volcanics, dated at 3.8-: 0.1 m.y. (G. H. Curtis,
commun., 1971), and, if my interpretation of the struc-
ture in this area (fig. 3) is correct, is underlain by da-
cite dated at 42:01 my. (Mankinen, 1972).

At the southernmost locality correlative with the
Lawlor Tuff, two thin tuffs in the Livermore Gravels of

18 CORRELATION OF LATE CENOZOIC TUFFS, COAST RANGES, CALIFORNIA

Clark (1930) are exposed; the lower bed is approxi- by 7.6 m of tuffaceous sediments and were probably
mately 3 m thick (fig. 9, locs. 31 and 32), and the upper erupted within a short period of time of each other from
bed is approximately 1.8 m thick (fig. 9, locs. 33 and a common vent in the Sonoma volcanic field. Samples
34). Both tuffs are water laid, well bedded, laminated, of the glass separated from the two tuffs have very
and, locally, crossbedded. The two tuffs are separated similar minor- and trace-element concentrations and

: Central Coast Ranges

 

 

 

 

 

 

 

 

     

 

 

 

 

 

 

 

 

 

 

 

    

 

 

 

 

     

 

    

 

 

 

 

 

 

 

 

 

 

 

 

 

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“Miller. use v 5v .2
5 _ “This study V (AV g
aSavage. 1951 Vv T:
'Edward Mankinen. oral commun.. 1974 vW >
”Edward Mankinen. 1912 «:v
n v V
Evernden Incl others 1 9 6 4 s ‘0
. 5.4 I 0.2—— —
"Bartuw and others, 1973 _ _ L.
”Jundn, ”55 Pmole Tu" and tufls In lower vv— 51
"Jean Firby-Durham, am commun.. 1974 Part 0' M°“‘IC'“° Road ‘ ,
WC‘IO"
6 _

FIGURE 9.—Summary of correlations of late Cenozoic tuffs based on chemical fingerprinting and petrographic characteristics of tufi's,
stratigraphic position and sequence, potassium-argon ages, and fossil evidence. Solid horizontal lines indicate correlation certain;
dashed horizontal lines indicate correlation probable; and queries indicate correlation uncertain. Location of sections shown in
figure 1.

are hard to distinguish by these analyses (table 7).
Neutron activation analyses, however, indicate that
the glass composition of the two tuffs is distinct (H. R.
Bowman and Sarna-Wojcicki, unpub. data). Similarity

TUFF CORRELATIONS

 

 

| Northern
T Sacramento Valley
3 u
u = I I! 5 S E
5 a .3 S g E e 0 8: g
o c “ 3 a ‘ E )~ . _ l-
5 3 ° 9 w s .2 a 2 g z =-
' ‘5 0 ~ in . i z :
o “ 3 ° 3 t “ a > ° § §
.: g 0 a c E a l- .5
v- u o o u .. .l
g o t a a 8 c 3 °‘ u S
2 " 5 s E s .2 w 5 S e z
. - >.
~ 9 E v a; . - 3 2 .~ 0 a
E : L ~ . 0 = E : C 2
n o > - ‘— 0 . _
1’ " 0 0 a o a 2 a o
- U c m > a s > U 3 o .2 = 3 >
.aa ”a; :2 g: g: g: a_: 2,:
i3 83: ES .53 £3 453 5:33 5:33
3.! tags 30 .20 go .20 520 can
.— a g > > m > z z
D 6: 0.02
7 Erosional urine.
1 1 :::.::::
1 2 20.7’
Irvingtonian
fauna
3
'a
o
a
a
t:
u
s E»
_ _ .‘g 8
t—j __'I —_ _E1 *| “>-
— ._ - —_ _ 5- mom
i c -| :‘_ Bluncan'Lo-u Fttl (Burn
0- ._ .4 . _
PE 4 _~_- fauna hE";
f' E1 ‘_". 841 .fi' 3
°1 - — . l—- u.
u‘] - - u, Nomlakl Tu" 7
E 1 '__. E Member 2 0‘
l- '%-| __.__ a (type localitv) I" V‘W
a ' - ._ ~ _ v v
l” .2" - ' 3 I. .1 to.
_ — - 5
so — ' - E EXPLANATION
:- E
._ - n
4.0:”)1 {>1 0 E
....«._ :
.c 4 '5
7: '3'. = Volc-nic flow
rg E .‘u- o z.
r g ._ .m e c
D ‘ - - ': e
r .3 is - ~ 3
E u _ 2 t,
.‘E c . 't
:— Homphillian' _ N t _ | Clastlc sedimentary deposi I
5- D 3 l' “- WV
- i ., s —' We
— HempA .— E i'_ «LI
— E him“ . . . . l: E L' Tuff
2 fauna _ i- E- I
63c “ L “.1
633 F :31 2 Approximate position of fossil
:8 -| '5 assemblage
' at
63A :1 :1
c f-E -l 5 7
63 3 I'. 32.4 Location of chemically analyzed
_ '- r_U-_.I \‘5 sample. See fig. 1
i- 2 _. ._ [- __] V
_. o c
= _ - .1. u 52c
43 5 35-37 33“" 41.4" E: Locution of samples analyzed by
v I " V 7 > npid scan method
_‘ 5.7106 _ .s.1go_1 __ L :15
' _ " a
._ .i l'_ .1
_—— L— L —_| Reversed ma netic polarity
Green Valley I ‘i "I i' 3—] g
Formation F334 34 t 0.4
r- ”I
L‘J T‘g E'J K-Ar we. in m.y.
L": PM

 

 

 

 

 

 

 

 
   

 

 
    

  

 

 

 

 

 

 

 

 

 

 

 

 

 

   

FIGURE 9.—Continued.

    
 

  
       

 

Fresno County (not shown on

fig. 1)

Southeastern San Joaquin Valley

Pumice ash at
Friant

       

<

 

Laucustrino

  

lay Member

.l'.|._|.l.

u.

doran'. E111.

Cor

19

coefficients comparing these two tufi‘s with tuffs at
other localities correlative with the Lawlor show great-
er similarity in every instance between the lower bed
and the Lawlor eruptive unit (table 8).

San Joaquin I
Valley

NJ

80

60

4O

20

 

FREQUENCY, IN PERCENT

Brown hornblende
Green hornblende
Brown hornblende

Green hornblende

0
.8 ‘D
c :
2 .1;
g c
L I.
O O
J: .c

l:
l:
o g
33 9
0 ED

FIGURE 10.—Principa1 mafic mineral frequencies of three size fractions
of tuff in Merced(?) Formation of Sonoma County. Frequency counts
were made on coarse pumice-lapilli tufT (10c. 37, table 5). A, 28—48
mesh. B, 35—100 mesh. C, 60—120 mesh.

Hypersthene
Augite
Hypersthene
Augite
Hypersthene
Augite

/ \

Rb/ \F‘b
/ \

 

 

A .. .
O
(i\ . .9.”
O
\9
v v y
Sr Zr
// \ \
Rb o Rb
B ’\ O
/.\ .
I/ 0". ‘..o
l 0
AL AL )1
Sr Zr

FIGURE 11.———Correlation of the Pinole Tuff with the Sonoma
Volcanics. Mutual percentages of net intensity peaks for
Rb, Sr and Zr. Intensity rapid peaks obtained by using
rapid X-ray fluorescence scans on powdered whole-rock
samples treated with 10 percent HCl. A , Tuffs in the Pinole
Tuff at Rodeo, Wilson Point and south of town of Pinole. B ,
Tuffs and flows of Sonoma Volcanics, Monticello Road, east
of Napa. Tufi's of intermediate composition containing
bread crust scoria bombs are included within dashed lines.

Although the refractive indices of glass for the Law-
lor eruptive unit are virtually the same for all samples,
the mafic-mineral abundances vary considerably (table
5). These differences cannot be explained by eolian or
hydraulic sorting since the tuff at all but one of the
localities correlative with the Lawlor appears to be an
ash flow. Variations in mafia-mineral frequencies may
be due to inhomogeneous distribution of crystals in the
magma prior to eruption. Alternatively, the Lawlor

 

0 CORRELATION OF LATE CENOZOIC TUFFS, COAST RANGES, CALIFORNIA

EXPLANATION

Pinole Tuff

I
Tuffs in Tassaiara area,
south of Mount Diablo

    
 

Rb

Sr Zr

FIGURE 12.—Correlation of the Pinole Tufl‘ (loc. 52A, B, and C) with
tuffs south of Mount Diablo (loc. 63A, B, and C). Mutual percent-
ages of net intensity peaks for Rb, Sr and Zr. Intensity peaks
obtained by using rapid X-ray fluorescence scans on powdered
whole-rock samples treated with 10 percent HCl. Samples from a,
gray pumice-lapilli tuif near the base of the Pinole Tufl' (loc. 52A),
and basal tuff south of Mount Diablo (10c. 63A); b, intermediate
tufl‘ with scoria bombs in the Pinole Tufi‘ (10c. 52B), and similar
finer grained tufi‘ south of Mount Diablo (loc. 63B); 0, silky silvery
pumice lapilli from tuffaceous matrix near top of Pinole Tufi‘ (10c.
52A), and from near top of tufi sequence south of Mount Diablo
(10c. 63C).

Elevation in section.
in metres

300 4“/ Contra Costa Group

Tassaiara Formation
//Tuff with rounded,
‘\ silky, silvery pumice

lapilli (loo. 63C)
Tuff with scoria lapilli

  
  
    
  

Turf with rounded,
silky, silverv pumice
lapIIII (loc. 52C) 200‘

 

   

 

 

 

Pinole Tuff

2t '
/

 

Tuff with scoria 100 4 5;;‘5 G:;:°§ansile-lapilli
bombs (Ioc. 52B) ,’ tuff (Ioc. 63A)

Grev pumice-lapilli
tuff (loc. 52A) 0

 

 

Green Valley Forma-
tion of Clark (1943)

 

__/Neroly Formation

Rodeo section
FIGURE 13.——Correlation of Pinole Tuff at Rodeo (10c. 52A—C) with

tufi‘s in Highland syncline section, south of Mount Diablo (10c.
63A—C).

Highland syncline section

2000
1600
1200
800
400

1600
1200
800
400

O

o c o .— o—- o o c :— .—- n
b is in iv in 'o is in i9 27: E:
CONCENTRATION. IN PARTS PER MILLION
o

 

CONCENTRATION, IN PERCENT (IRON)

FIGURE 14.—Concentrations of minor and trace elements in volcanic
glass of Lawlor Tuff and its correlatives. A—C, Lawlor Tuff (fig. 5,
lacs. 22, 23, 25). D-H, Lawlor correlatives (fig. 5, locs. 17—19, 30,
31). Iron in percent; remaining elements in parts per million.

TUFF CORRELATIONS

Tuff and its correlatives may actually represent sev-
eral separate eruptions closely spaced in time.

The Lawlor Tuff and its correlatives form an erup-
tive unit extending over 112 km, interbedded with the
upper part of the Sonoma Volcanics, the base of the
Tehama Formation, the uppermost(?) part of the Tas-
sajara Formation, and the Livermore Gravels of Clark
(1930).

PUTAH AND NOMLAKI TUFF MEMBERS
OF THE TEHAMA FORMATION

A thin tuff bed (fig. 9, 10c. 16) correlative with the
Putah Tuff Member of the Tehama Formation of the
western Great Valley (fig. 9, locs. 12—15) has been
found south of Suisun Bay, stratigraphically above the
Lawlor Tuff. This thin tuff bed is interbedded with sed-
iments which have been referred to as the Los Medanos
Formation (Clark, 1943) or the Wolfskill Formation
(Weaver, 1949) but have been recently designated as
the Tehama Formation (Sims and Sarna-Wojcicki,
1975) on the basis of lithologic correlation with the
type Putah Tuff Member. This correlation extends the
maximum distance between correlative localities (locs.
15, 16, fig. 1; fig. 9) of the Putah Tuff Member to ap-
proximately 97 km.

The Putah Tuff Member is a composite unit of
water-laid tuffs and probably represents several erup-
tions closely associated in time. Similarity coefficients
for unweathered samples within the Putah (fig. 4, locs.
12, 13, and 14) are 0.91, 0.89, and 0.95. Coefficients
between these samples and a weathered sample (fig. 4,
Ice. 15) are lower (0.83, 0.86, and 0.89) possibly owing
to higher concentrations of barium and strontium in
the form of insoluble authigenic sulfate in the weath-
ered sample. The southernmost correlative sample (fig.
4, Ice. 16) is most similar (similarity coefficient of 0.96)
to the sample (fig. 4, loc. 14) obtained from the lower-

 

21

 

Z
'2 9
o :i
51.6 E 1600
51.2 51200
§o.83, 800
30.4 E 400
g0.0 E 0
cz;1.<55_1¢;oo
:12 31200
:03 : 800

<
50.4: 400
30.05 0
E u
U 6

0

FIGURE 15.—Concentrations of minor and trace elements in volcanic
glass of the Putah Tuff Member, a Putah correlative south of
Suisun Bay, and the Nomlaki Tuff Member (locs. 8—11) from its
type locality. A—C, Putah Tuff member of Tehama Formation (locs.
12—14). D, Putah correlative, south of Suisun Bay (10c. 16). E—H,
Nomlaki Tuff Member of Tehama Formation (locs. 8—11).

most emplacement unit at its type locality.

Miller (1966) has shown that the Nomlaki Tuff
Member (fig. 1, locs. 8—11), exposed within and near
the base of the Tehama Formation in northern Sac-
ramento Valley, is not correlative with the Putah (locs.
12—16) although both tuffs are about the same age3 and
in similar stratigraphic position. Miller’s conclusions
were confirmed during this study by chemical finger-
printing of glasses from the two tuffs (fig. 15).

Average within-unit similarity coefficients for the
Putah and Nomlaki Tuff Members of the Tehama
Formation are 0.90 and 0.92, respectively, while the
average similarity coefficients between the units is
0.63 (fig. 4). Samples of the Putah (locs. 12—15) and its
correlative (10c. 16) are clustered at distance function
values of about 0.050; the samples from both the Putah
and Nomlaki Tuff Members are grouped at values of
0.260 (fig. 5).

3The Nomlaki has been dated by potassium-argon methods at 3.3104 m.y. (Evernden and
others, 1964); the Putah at 33:01 my. (Miller, 1966; G. H. Curtis, oral commun., 1971).

TABLE 6.—Average minor- and trace-element composition of volcanic glass of the physically continuous Lawlor Tuff unit compared with

average compositions of correlative but physically separate outcrop localities
[Sample localities shown in figure 1. Concentrations of iron in percent; all other concentrations in parts per million]

 

 

Fe Ti Ba . Mn Zr Rb Sr Zn Y Nb Ga Cu Ni
Lawlor Tuff, average of seven
analyses (1008- 22-29) ______ 1.73 1160 795 444 311 147 56 58 23 19 17 9 11
Lawlor correlatives, average of
eleven analyses (locs. 17—21,
29L34) ____________________ 1.72 1193 791 448 311 146 64 60 29 15 17 11 11

 

TABLE 7 .—Trace— and minor-element analyses of volcanic glass of two thin water-laid tuffs in the Livermore Gravels of Clark (1930)

[Concentrations of iron in percent; all other concentrations in parts per million]

 

 

Sample 10c. Fe Ti Ba Mn Zr Rb Sr Zn Y Ga Nb Cu Ni

Upper bed ____________ 34 1.82 1137 718 517 290 137 82 56 24 13 9 8 8
do ________________ 33 1.82 1136 684 502 306 135 74 60 23 14 21 13 11
Lower bed ____________ 32 1.75 1213 733 431 297 143 60 58 25 17 16 11 13
do ________________ 31 1.70 1134 809 422 305 148 71 59 29 17 14 9 12

 

22

TABLE 8.—Average similarity coefficients comparing trace- and
minor-element analyses of volcanic glass of two thin water-laid tuffs
in the Livermore Gravels of Clark (1930) with all other outcrop
localities of the Lawlor Tuff

 

Tuffs in Livermore Gravels

 

Upper bed Lower bed
(loss. 33, 34) (locs. 31, 32)
Upper bed __________________________ 10.95 0.92
Lower bed __________________________ .92 2 .96
South of Mount Diablo
(sample 30) ______________________ .90 .94
South of Mount Diablo
(sample 29) ______________________ .90 .93
Lawlor Tuff (samples 22—28) -L ______ .90 .95
Southeast of Sonoma Volcanics
(samples 19—21) __________________ .89 .94
Sonoma Volcanics Monticello Road
(sample 17) ______________________ .86 .91
Sonoma Volcanics near Schellville
(sample 18) ______________________ .93 .94

 

'Sample from locality 33 compared with sample from locality 34.
2Sample from locality 31 compared with sample from locality 32.

Mafic-mineral frequencies of samples of the Putah
Tuff Member (table 3) are similar, as are the refractive
indices of glass (table 5); the same is true for the Nom-
laki Tuff Member. There are significant differences in
mafic-mineral frequencies between the two tuffs; how-
ever, differences in refractive indices of glass between
the Putah and Nomlaki are very slight (table 5).

Trace- and minor-element composition of the vol-
canic glass in the Putah Tuff Member is very similar to
that of the tuff in the Merced(?) Formation of Sonoma
County. Although the average similarity coefficient
between the Putah and the tuff in the Merced(?) For-

 

mation of Sonoma County is 0.85, individual sample

CORRELATION OF LATE CENOZOIC TUFFS, COAST RANGES, CALIFORNIA

pairs from the two tuffs may have similarity coeffi-
cients as high as 0.91 (fig. 4) for the eight-element
comparison used. It was not possible to distinguish
clearly between the two tuffs using cluster analysis on
the main group of eight elements or on a second run
using seven elements, omitting strontium. This is due
both to the chemical similarity of the glass of the two
tuffs and to a rather high variability for manganese,
rubidium, and strontium. It appears that chemical var-
iability of the glass for some elements can differ for
different eruptive units. Elements with consistent con-
centrations in one unit may be more variable in
another. For instance, amounts of rubidium in the
Lawlor Tuff are very consistent, while those in the
Putah and the tuff in the Merced(?) Formation of
Sonoma County are more variable. The two last tuffs
are known from independent evidence to be of different
age: the Putah was dated by potassium-argon analysis
at 3310.1 m.y. (fig. 9, locs. 12—15; G. H. Curtis, oral
commun., 1971), while the tuff in the Merced(?) For-
mation of Sonoma County was dated at 5.7: 0.6 (fig. 9,
locs. 35—37) and 6.1:0.1 m.y. (fig. 9, locs. 38—40). Calcu-
lations of similarity coefficients and cluster analysis
were performed on samples of these tuffs using only
the four most consistent variables: iron, titanium,
barium, and zirconium (fig. 16). By this procedure it
was possible to distinguish differences in composition
between the two tuffs. On the basis of these calcula-
tions, the average similarity coefficient between sam-
ples of the Putah and the tuff in the Merced(?) Forma-
tion is 0.82, while the average internal within-unit
similarity coefficient for both units was 0.93. The high-
est similarity coefficient for a pair of samples from the
two tuffs was 0.88. By means of cluster analysis with

 

 

Samplei
1°C. 14 13 1215 16 35 36 37 38 39 40 41 42 43 44
Putah Tuff Member of 14 1
Tehama Formation 13 .96 1
(loc.12-15)anda 12 .93 .94 1
correlative tuft (10c. 15 .92 .91 .90 1
16) 16 .97 32.92.93 1
35 .87 .88 .83 .80 .84 1
36 .85 .86 .81 .76 .83 .97 1
Tuffinthe Merced(?) 37 .83 .84 .79 .76 .80, .89 .92 1
Formation of Sonoma
County 38 .85 .85 .81 .78 .83 .90 .92 .94 1
39 .84 .86 .81.78 .82 .93 .94 .93 .94 1
4o .83 .84 .79 .76 .80 .95 .94 .95 .97 .97 l
Tuffin the Petaluma 41 .80 .81 .77 .74 .78 .90 .92 .95 .94 .95 .96 1
Formation 42 .84 .85 .80 .77 .81 .91 .94 .96 .97 .94 .97 .95 1
Tuffsouth ofMount —— 43 .84 .84 .80 .78 .81 .94 .95 .91 .90 .94 .92 .92 .92 1
Diablo
Tuffnear Lafayette — 44 .87 .87 .85 .81 .87 .94 .92 .85 .85 .87 .86 .85 .86 .92 1

FIGURE 16.—Simi1arity coefficient matrix comparing trace- and minor—element analyses
of glass samples of the Putah Tuff Member of Tehama Formation (locs. 12—16) and the
tuff in the Merced(?) Formation of Sonoma County. Calculations of coefficients for the
four most consistent elements, Fe, Ti, Ba, and Zr.

TUFF CORRELATIONS

23

SAMPLE NUMBER

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

a) _n _\ .1 a .a b u J> (.0 (a) w :5 A b (A 0'1 0'! U1 0') 5 O? O) O)
on yo mama hmumuwmoAm s: on no) a} 5 mm
0
c__v_,
W—4
|
< —"_
(D ‘—fir—’
3
,.. l
_v__,
V
| , -
W »——v—r 9.
Fine I 2
W“ ash :
fl—I --
..
Coarse g
pumice 0-
E‘
Z I:
9 5'
l-
o 1.?
2 3
a Putah TUff Tuff in Merced(?) %- _
m 0'2 _ Member Of Formation of E
U Tehama Sonoma County 1'1 ___v_,
2 Formation _v_« o .
< _ é‘ Tuff m
a —— Pnnole n, Tassajara
_ Tuff 1’- Formation
o g .
0.3 — _
0.4— V -

FIGURE 17.—Dendrogram from cluster analysis of trace- and minor-element data, using distance function, for Fe, ’I‘i, Ba, and Zr.
See text for explanation. Sample number is same as locality number shown in figure 1.

only these four elements, it was also possible to distin-
guish between the two eruptive units. To emphasize
differences between samples, the cluster analysis in
this instance was run only on samples of the Putah
Tuff Member, the tuff in the Merced(?) Formation of
Sonoma County, plus several close compositional rela-
tives (fig. 17).

TUFF IN THE TYPE SECTION OF THE MERCED FORMATION

A correlative of the tuff in the type section of the
Merced Formation of western San Francisco peninsula
(fig. 1, loo. 1) has been obtained from a drill hole 10
miles to the east, in sediments of the Alameda Forma-
tion beneath San Francisco Bay (fig. 1, 10c. 2): The

similarity coefficient for analyses of seven elements
(titanium, barium, manganese, zirconium, rubidium,
strontium, and zinc) in the volcanic glass of these two
tuffs is 0.93. No iron analyses have as yet been made
on these two samples, so they are not included in the
cluster analysis (fig. 5). A tuff similar to that in the
Merced and Alameda Formations was exposed in a
trench in the Santa Clara Formation, in the town of
Woodside (fig. 1, locs. 3 and 4) approximately 20 miles
south of the former localities. Though the tuff at the
Woodside locality has the same mineralogy as the tuffs
in the Merced and Alameda Formations (table 5), ear-
lier analyses had indicated that there are considerable
differences in titanium and manganese content of the

 

24 CORRELATION OF LATE CENOZOIC TUFFS, COAST RANGES, CALIFORNIA

glass. Similarity coefficients between samples 1 and 2
on the one hand, and 3 and 4 on the other, range be-
tween 0.81 and 0.87, with an average of 0.84. On the
basis of the earlier analyses alone, the correlation of
the tuff in the Santa Clara Formation with the tuff in
the Merced and Alameda Formations must be consid-
ered uncertain. However, new analyses by Brent
Fabbi, US. Geological Survey, Menlo Park, of tuff in
the Santa Clara Formation and in the type Merced
Formation show a high similarity coefficient of 0.97,
indicating that the tuffs are correlative (Fabbi and
Sarna-Wojcicki, unpub. data). The earlier analyses are
probably inaccurate owing to incomplete separation of
crystals and lithic fragments from the fine-grained vol-
canic ash.

The tuff in the Merced Formation is fine grained and
probably was deposited by water. It has no coarse-
grained facies within the central Coast Ranges that
might indicate local eruptive sources, and it differes in
glass chemistry from tuffs of local provenance. For in-
stance, the similarity coefficients between the tuff in
the Merced Formation (sample 1) and tuffs of local
Coast Range provenance, such as the Putah Tuff
Member (samples 12—15), the Lawlor Tuff (samples
22—28), and the tuff in the Merced(?) Formation of
Sonoma County (34—40), are low (0.59, 0.62, and 0.54,
respectively). The similarity coefficient between the
tuff in the Merced Formation and a tuff-breccia in An-
derson’s (1936) Cache Formation within the Clear
Lake volcanic field (sample 71) is also low (0.66). This
indicates that the Merced tuff probably did not have its
source in the Clear Lake area either, even though the
period of volcanism in the Clear Lake area encompas-
ses the age of the tuff in the type section of the Merced
Formation (G. H. Curtis, oral commun., 1971). A
15:08 m.y.-potassium-argon date on tuff in the
Merced Formation (fig. 9, loo. 1; Hall, 1966) is younger
than the youngest known potassium-argon age ob-
tained on rocks of the Sonoma Volcanics (2.9 m.y.,
Mankinen, 1972). These ages, if correct, further
exclude the Sonoma volcanic field as a likely source of
this tuff. However, the similarity coefficient between
the tuff in the type section of the Merced Formation
and the average for the Nomlaki Tuff Member, a unit
of known Cascade Range provenance (Anderson and
Russell, 1939; Lydon, 1967), is 0.81, a value typical of
provincial "relatives,” suggesting that the tuff in the
type section of the Merced Formation was erupted in
this volcanic province.

On the basis of glass chemistry and petrography, as
well as radiometric ages, it seems likely that the
source of the tuff in the type Merced, Alameda, and

Santa Clara Formations was in the southern Cascade

Range, near the town of Mineral, where two Pleis-

 

tocene pumice ash-flow units crop out (Wilson, 1961).
These two pumice ash-flow units yielded scattered
potassium-argon ages ranging from 0.26 to 1.1 m.y.
(Gilbert, 1969).4 Though earlier analyses have indi-
cated that the tuff in the type Merced Formation (fig. 9,
loc. 1) is not correlative with one of the ash-flow units,
exposed near Lassen Lodge (fig. 1, loc. 7), new analyses
(Fabbi and Sarna-Wojcicki, unpub. data) indicate that
the tuff in the type section of the Merced Formation is
probably correlative with another ash-flow unit, ex-
posed near Manton Lodge; the similarity coefficient for
these two tuffs is 0.90.

The mafic mineralogy of the tuff in the type section
of the Merced Formation (fig. 1, Ice. 1) and its local
correlatives (fig. 1, locs. 2—4) is the same as that of the
pumice ash flows near Mineral (fig. 1, Ice. 7). Both
groups of tuffs have dark-green hornblende and pale
pleochroic hypersthene as the principal mafic pheno-
crysts (table 5). The mafic mineral frequencies are dif-
ferent; the pumice tuff at Mineral has more
hypersthene and less hornblende than the tuff in the
Merced Formation. These differences can be explained
by either hydraulic or eolian sorting of these minerals
away from their source. Fragments of the thinner,
tabular, and more cleavable hornblende would proba—
bly be carried further by wind or water than the stub-
bier, equant hypersthene crystals. The refractive in-
dices of glass of the tuff in the type section of the Mer-
ced Formation and its correlatives are nearly the same
as those at Mineral (table 5).

DISCUSSION

Five widespread late Cenozoic tuffs, ranging in age
from approximately 1 to 6 m.y., have been identified in
the central Coast Ranges of California by means of
chemical analyses of volcanic glass, potassium-argon
dating, and petrographic and stratigraphic evidence
(fig. 9). These units provide five temporal horizons that
make it possible to correlate late Cenozoic volcanic,
alluvial, lacustrine, and marine deposits.

Four of the five widespread units were erupted from
source areas within the central Coast Ranges, probably
within the area of the Sonoma volcanic field. These
tuffs include the tuff in the Merced(?) Formation of
Sonoma County, the Pinole Tuff, the Lawlor Tuff, and
the Putah Tuff Member of the Tehama Formation.

Several tuffs in the central Coast Ranges (fig. 1, locs.
1—6), including one of the five widespread units, the
tuff in the type section of the Merced Formation (fig. 1,

‘The 1.5:0.75-m.y.-date on the tuff in the type section of the Merced Formation is very
imprecise owing to high content of atmospheric argon and possible detrital contamination.
Ages on its probable chemical correlative in the southern Cascade Range are scattered,
ranging from 0.26 to 1.1 m.y. (Gilbert, 1969). Consequently, the age ofthe tut? in the Merced
Formation is not well determined but is probably about 1 m.y. or younger.

\

DISCUSSION

locs. 1—4), were probably erupted in the southern Cas-
cade Range. All are fine-grained water-laid or ash-fall
tuffs that, unlike tuffs of local derivation, have no
coarse—grained correlatives in the central Coast
Ranges. These tuffs are similar in composition to tuffs
of the southern Cascade Range and differ from tuffs of
the Sonoma volcanic field, the Clear Lake area, and the
Sierra Nevada. For example, similarity coefficients for
Coast Range tuffs of inferred Cascade Range prove-
nance compared with tuffs of the Sonoma volcanic field
range from 0.50 to 0.66, with an average of0.61 (fig. 4).
Within-province similarity coefficients for tuffs of the
Sonoma volcanic field average 0.75, while coefficients
for southern Cascade tuffs compared with Coast Range
tuffs of suspected Cascade Range origin are also 0.75,
strongly suggesting that the latter two sets of tuffs are
provincial relatives.

The tuff in the type section of the Merced Formation
is 15—60 cm thick wherever it is found in the bay area
and contains glass-coated green hornblende laths and
glass shards up to 0.5 mm long. It is unlikely that the
ash was carried by air 320 km to the Merced embay-
ment, in View of its considerable thickness and rela-
tively coarse maximum crystal and shard size. Fur-
thermore, prevailing wind directions must necessarily
have been northerly, rather than westerly as they are
at present, in order to carry the tuff southward by
wind. The purity of the tuff at some of its exposures
may be due to the low density of the glass shards—

\ a drainage basin blanketed with ash of low density

(\\,)

will probably first move that material before mov-
ing the denser normal bedload. Furthermore, if the

‘3 tuff had been carried by wind to the Merced deposi-

tional basin, the tephra lens of such an eruption would
be at least 320 km long and several tens of kilome-
tres wide. The record of such an eruption would likely
be preserved throughout the Pleistocene deposits of
the northern Great Valley, yet no such tuff has been
reported.

If this line of reasoning is correct and the tuff in the
Merced Formation was erupted in the southern Cas-
cade Range, then it seems most likely that the ash was
brought to the marine Merced embayment by the an-
cestral Sacramento River, rather than transported by
air. The presence of a water-transported tuff of Cas-
cade Range provenance in the marine Merced Forma-
tion therefore indicates that Great Valley drainage to
the Pacific Ocean in the vicinity of the bay area had
been established by late Merced time, or about 1 my.
ago.

Whether the tuff in the type section of the Merced
Formation was actually transported to the Merced em-
bayment by air or water, another line of evidence indi-
cates that Great Valley drainage to the ocean in the

 

25

.vicinity of the San Francisco Bay area had been estab-
lished by the time the tuff was deposited. Hall (1966)
studied the mineralogy of sediments in the type section
of the Merced Formation and found an abrupt
mineralogical change in the upper part of the forma-
tion. Heavy-mineral grains below this change are of
local provenance, while those above this change indi-
cate a sudden influx of Great Valley sediments into the
Merced embayment. The tuff in the type section of the
Merced Formation lies 46 m stratigraphically above
this mineral change.

The Putah and Nomlaki Tuff Members of the
Tehama zFormation and the Lawlor and Pinole Tuffs
(3.3, 3.4: 4.0 and 5.2 my. old, respectively) are re-
stricted to the eastern part of the Coast Ranges and
have not been found in coeval marine formations in the
western part of the central Coast Ranges, suggesting
that a north-south drainage divide existed in the cen-
tral part of the Coast Ranges prior to about 1 my. ago
and that Great Valley drainage flowed to a southerly
outlet during this period. A southerly connection be-
tween the ocean and the Great Valley was in existence
until late Pliocene time, as indicated by the presence of
the upper Pliocene continental and marine San Joa-
quin Formation in the southern San Joaquin Valley
(Woodring and others, 1940). Subsequently, this
southerly connection was closed off, as evidenced by
the presence of the extensive lacustrine Corcoran Clay
Member of the Tulare Formation beneath Pleistocene
alluvium in the San Joaquin Valley (J anda, 1965). The
presence of this unit in the southern Great Valley indi-
cates that Great Valley drainage was temporarily
ponded. The Corcoran interfingers to the west with al-
luvial deposits of the Tulare Formation (Wahrhaftig
and Birman, 1965), which in turn overlies the marine
San Joaquin Formation. The exact age range of the
Corcoran is not known, but the member is overlain at
Friant by ash and pumice dated at 0.6:002 m.y.
(J anda, 1965). The presence of Pleistocene alluvial de-
posits above the Corcoran suggests that drainage from
the Great Valley to the ocean had been reestablished,
probably via a more northerly outlet. The drainage
change from a southerly outlet to one near the present
site of San Francisco Bay probably took place some-
time after 3.3 m.y. ago, after the eruption of the Nom-
laki and Putah Tuff Members, but before about 0.6
m.y. ago.

The texture of the Lawlor Tuff at all its outcrop
localities, except for the southernmost locality south of
Livermore (fig. 1, locs. 31—34), is typical of an ash flow.
N o stratification, lamination, or vertical size gradients
have been observed. The presence of the ash-flow phase
of the Lawlor Tuff south of Mount Diablo suggests that
neither Suisun Bay nor Mount Diablo existed at the

26

time of the eruption, about 4 m.y. ago, and that these
features were formed later. The tuff was erupted in the
southeastern Sonoma volcanic field, where its coarsest
facies are found, and it would have been difficult or
impossible for the ash flow to cross these topographic
features had they existed at the time of the eruption. A
gentle topography or a slope component probably
existed along the line between the southeastern mar-
gin of the Sonoma volcanic field and the southernmost
exposure of the ash flow, south of Mount Diablo (fig. 1,
10c. 30).

Correlative localities of the tuff in the Merced(?)
Formation of Sonoma County trend diagonally across
the central Coast Ranges (fig. 9) and correlative tuffs
are found both in the southeast, interbedded with con-
tinental sediments, as well as in the northwest part of
the study area, interbedded with marine deposits.
Heavy minerals in sediments of the Merced(?) Forma-
tion of Sonoma County are of local Coast Range prove-
nance; there is no evidence that Great Valley material
was brought into the embayment during Merced(?)
time (Johnson, 1934).

Correlatives of some of the tuffs examined in this
study, such as the Putah Tuff Member of the Tehama
Formation and the Lawlor Tuff, are undoubtedly pre-
served to the east under the Quaternary sediments of
the Great Valley, beneath which both tuffs dip.
Likewise, new correlative localities of the Putah Tuff
Member of the Tehama Formation and the Lawlor and
Pinole Tuffs will quite likely be found in the future in
the Sonoma volcanic field, which has been only
peripherally examined in the present study. The tuff in
the Merced(?) Formation of Sonoma County, the oldest
of the five major eruptive units, may antedate the main
period of volcanism in the Sonoma volcanic field or
may represent the inception of that volcanism and lie
buried under the younger volcanic deposits.

Radiometric ages on the youngest tuffs and flows
erupted in the Sonoma volcanic field cluster in the
range 3.0 to 4.0 m.y. (2.9, 3.3, 3.3, 3.8, 4.0, 4.0, 4.2
m.y.). This cluster of dates defines a maximum age for
a late Pliocene or early Pleistocene orogeny that de-
formed and uplifted the formations containing the vol-
canic units. The eastward shift of progressively
younger eruptive units from the Sonoma volcanic field
at the western margin of the Great Valley (fig. 8)
suggests that uplift and volcanism were proceeding
simultaneously. This orogeny, or perhaps displace-
ment on the San Andreas fault, or both, closed off the
sea connection between the southern Great Valley and
the ocean. Sometime after this pulse of deformation
and perhaps as a consequence of it,,drainage in the
Great Valley found an outlet to the ocean in the vicin-
ity of the San Francisco Bay area.

 

CORRELATION 0F LATE CENOZOIC TUFFS, COAST RANGES, CALIFORNIA

DESCRIPTION OF UNITS

THICK SECTIONS OF VOLCANIC DEPOSITS

SONOMA VOLCAN ICS, MONTICELLO ROAD SECTION,
SOUTHEASTERN PART OF SONOMA VOLCANIC FIELD,
EAST OF NAPA (FIGS. 1—3, 9, LOCS. 17, 45—51)

Approximately 1 m of gray pumice lapilli tuff at the
base is overlain by at least 12 m of a dark andesitic tuff
containing round scoriaceous lapilli and bombs as
much as 20 cm in diameter. This is overlain in turn by
approximately 240 m of light-gray to cream dacitic vit-
ric pumice-lapilli and lithic tuff, which is locally
welded and intruded in at least one place by andesitic
dikes.

This group of beds is overlain by approximately 215
m of massive flow-banded dacite. The uppermost 3 m of
the unit consists of gray porphyritic perlite, overlain
by a jumble of angular dacite and perlite boulders in a
tuffaceous breccia matrix derived by infilling from the
overlying unit.

The dacite flows are overlain by 150 m of coarse daci-
tic pumice Iapilli and pumice blocks as much as 40 cm
long. The pumice is gray, rather hard, and dense. In-
terstices between the pumice clasts are often filled
with a creamy soft opaline(?) material and dark-
orange-brown clay (nontronitic montmorillonite). The
top of this unit is locally channeled, and the channels
contain boulders of andesite, dacite, and rhyolite as
much as 1 m in diameter.

The pumice-block breccia is overlain by approxi-
mately 18 m of a lithic pumice-lapilli tuff, with coarse
boulders of andesite, dacite, and rhyolite at its base.
This unit is overlain in turn by about 24 m of tuffa-
ceous sediments containing rounded pumice lapilli. A
reddish paleosoil(?) is developed at the top. The unit is
channeled at the top; the channels contain pebbles of
basalt, andesite, andesite scoria, dacite, and rhyolite.

SONOMA VOLCANICS, SOUTHERNMOST SONOMA
VOLCANIC FIELD, NORTH OF SUISUN BAY (GOODYEAR
STATION SECTION; FIG. 1, LOCS. 19—21)

A sequence of pumice-lapilli and pumice bomb tuffs,
approximately 150 m thick, is exposed in a deep long
roadcut along the frontage road of California Highway
21, just north of Suisun Bay. The entire sequence is
massive and shows no stratification except for local
changes in particle size and a few zones, presumably at
the base of massive pumice-ash flows, where some of
the larger lithic fragments have accumulated. The
tuffs are overlain by a jointed andesite flow 15 m thick.

PINOLE TUFF (LOCS. 52—62)

The Pinole Tuff is a sequence of deformed layered

DESCRIPTION OF UNITS 27

pyroclastic deposits and tuffaceous sediments about
270 m thick, exposed northwest and south of the town
of Pinole and at the town of Rodeo south of San Pablo
Bay (Lawson, 1914; Vitt, 1936; Weaver, 1949). The
Pinole Tuff overlies andesitic sandstone of the Neroly
Formation of late Miocene age. There is no angular
discordance between the two formations at Rodeo, but
south and west of Pinole the tuffs rest on tuffaceous
shales of the lower part of the Monterey Formation
(middle Miocene). The section at Rodeo is thickest and
at the time of Vitt’s work (1936) was well exposed. At
present much of the section has been concealed by con-
struction.

A similar though somewhat thinner section is ex-
posed northwest of Pinole near Wilson Point, along the
south shore of San Pablo Bay and south of Pinole
where, according to Vitt, the upper part of the tuff is
cut off by the Pinole fault. The Pinole Tuff is actually
composed of several tuffs, breccias, and tuffaceous de-
posits. These various units differ considerably in bed-
ding structures, textures, mineralogy, and chemistry.

The Pinole Tuff does not contain any flow rocks or
intrusive rocks. It does, however, contain scoriaceous
andesite bombs as much as 1 m in diameter in the
"tuffaceous breccia” unit, which suggests that at least
this particular unit was deposited fairly close to source.

There are strong similarities between the Pinole sec-
tion and the Monticello Road section to the north. Both
sections contain fine- to medium-grained gray pumice-
lapilli tufi's near the base, are overlain by darker-
colored andesitic tuffs containing scoria bombs, and
are overlain in turn by lighter-colored more silicic
pyroclastic deposits.

WIDESPREAD TUFFS INTERBEDDED WITH
DETRITAL SEDIMENTARY DEPOSITS

WESTERN PART OF THE MAIN STUDY AREA

TUFF IN THE TYPE SECTION OF
THE MERCED FORMATION (LOC. 1)

On the west side of the San Francisco peninsula, a
30— to 60—cm-thick fine-grained hornblende-bearing
Vitric tuff is exposed in the cliffs along the beach just
south of Fleishhacker Zoo, in the type section of the
Merced Formation (loc. 1) (Lawson, 1914; Hall, 1966).
The tuff was deposited in marine water, is crossbedded
and laminated, and in places contains considerable
amounts of detrital material. Another outcrop of ap-
parently the same tuff is exposed in a steep hillside
north of Westmoor School southeast of locality 1. A tuff
similar to the one in the Merced Formation has been
found in a drill hole at 83 m below sea level in the
Alameda Formation beneath west central San Fran-
cisco Bay (Trask and Rolston, 1951; fig. 1, loo. 2). Still

 

another tuff (locs. 3 and 4) similar to the one in the
type section of the Merced Formation has been un-
covered 35 km to the southeast of locality 1, in the
Santa Clara Formation, in a trench cut near the San
Andreas fault zone at the town of Woodside.

Louderback (1951) and Hall (1966) suggested that
the tuff in the type section of the Merced Formation
and the tuff in the Alameda Formation are the same on
the basis of refractive indices of glass, grain size, and
mineralogy. Hall further suggested that the tuff may
have had its source in the southern Cascade Range,
near the town of Mineral, where two extensive pumice
tuff flows crop out (Wilson, 1961; Gilbert, 1969).

TUFF IN THE MERCEDG) AND PETALUMA FORMATIONS
OF SONOMA COUNTY (LOCS. 35-42)

Northwest of San Francisco in Sonoma County, a
tuff of variable texture and grain size is interbedded
with the lower and upper Pliocene Merced(?) Forma-
tion (Johnson, 1934; Weaver, 1949; Travis, 1952; Bar-
tow and Addicott, 1971).. This tuff is exposed almost
continuously for a distance of 14.5 km. The tuff, de-
posited by water and in places containing detritus and
invertebrate marine fossils, is coarsest in the east near
Trenton, where pumice bombs as much as 20 cm in
diameter are found, and near Roblar, where pumice
cobbles several centimetres in diameter are found. To
the west it becomes progressively finer and contains
more detrital contamination. Johnson (1934), Louder-
boack (1951), and Hall (1966) have pointed out that the
tuff in the Merced(?) Formation of Sonoma County and
the tuff in the type section of the Merced Formation
differ in mineralogy and refractive indices of glass and
are consequently not correlative. The source of the tuff
in the Merced(?) Formation of Sonoma County is not
known, although judging from the coarse pyroclasts it
contains, the source must have been nearby.

Still another exposure of a similar tuff has been
found at Sears Point, in the Petaluma Formation, just
north of San Pablo Bay, approximately 43 km south-
east of the Trenton locality (Bartow and others, 1973).
This tuff, also deposited by water, ranges in grain size
from Vitric-ash tuff to pumice-lapilli tuff.

SOUTHEASTERN PART OF THE MAIN STUDY AREA

In the east and southeast part of the study area (fig.
1), there are several tuffs exposed in late Cenozoic de-
posits most of which have been correlated with the
Pinole Tuff by Vitt (1936) on the basis of refractive
indices of glass and heavy mineralogy. However, many
of these correlations are not justified since the refrac-
tive indices of glass and heavy—mineral species and
frequencies differ widely between many of these tuffs.

28 CORRELATION 0F LATE CENOZOIC TUFFS, COAST RANGES, CALIFORNIA

LAWLOR TUFF (LOCS. 22—28)

The Lawlor Tuff, named for its type locality in Law-
lor Ravine, Nl/z sec. 23, T. 2 N., R. 1 W., Contra Costa
County, by Weaver (1949), is well exposed in the hills
northeast of Mount Diablo. It trends east-west from
near Markley Canyon in the east to near Port Chicago
in the west, a distance of 19 km. The tuff is exposed for
much of this distance, except for a short interval near
Arnold Industrial Highway where, according to Patten
(1947), it is cut off from its eastern and western expo-
sures by normal faults.

The tuff is approximately 18 m thick south of Port
Chicago and thins to the east, toward Markley Canyon,
where it is about 4.5 m thick. The unit is massive and
contains coarse light-bluish-gray to white pumice
lapilli and some angular lithic volcanic fragments that
are primarily bluish gray and brown felsite. The
pumice lapilli are angular and tightly interlocked. The
size of the lapilli decreases from west to east, from
about 5—8 cm in maximum diameter near Port Chicago
to about 0.6-1.2 cm at Markley Canyon. There is no
obvious sorting or stratification in the unit. Textural
features indicate that the Lawlor was most probably a
pumice ash flow.

The Lawlor Tuff disconformably overlies the upper
Miocene Neroly Formation along much of its length
except in the vicinity of Arnold Industrial Highway,
where it rests unconformably on the upper Eocene
Markley Sandstone Member of the Kreyenhagen For-
mation. The uppermost part of the Neroly Formation
contains white reworked pumice-lapilli tuff.

The Lawlor Tuff is overlain by the upper Pliocene
Tehama Formation (Sims and Sarna-Wojcicki, 1975),
formerly the Los Medanos Formation of Clark (1943, p.
189) or Wolfskill Formation of Weaver (1949), consist-
ing primarily of sand and gravel. A thin discontinuous
tuff, approximately 0.6 to 1.2 m thick, is about 8—9 m
stratigraphically above the Lawlor Tuff west of Arnold
Industrial Highway (10c. 16). The tuff contains rounded
pumice lapilli in a matrix of fine glass shards. On the
basis of its trace- and minor-element chemistry, mafic
phenocryst abundances, and index of refraction, it is
correlated with the Putah Tuff.

SOUTH ,OF MOUNT DIABLO

In the foothills immediately south of Mount Diablo
several tuffs are interbedded with tightly folded late
Cenozoic continental deposits. These strata are shown
on the Geologic Map of California (Rogers, 1966) as
“middle and/or lower Pliocene nonmarine sedimentary
rocks,” but the middle and upper part of the section

 

may be as young as late Pliocene or Pleistocene, at
least partly contemporaneous with the Pliocene and
Pleistocene Livermore Gravels of Clark (1930) to the
south, on the basis of correlation of the Lawlor eruptive
unit.

The relative stratigraphic position of at least four
tuff units is known. Perhaps three or four additional
tuffs have been distinguished during the present study
on the basis of their chemistry and mineralogy. Most of
the tuffs are discontinuous. Oestreich (1958) has at-
tempted to use the tuffs as marker beds for the contact
between the Tassajara Formation and the Green Val-
ley Formation of Clark (1943). Vitt (1936), again with-
out sufficient justification, has correlated all but one of
these tuffs with the Pinole Tuff on the basis of refrac-
tive indices of glass and heavy-mineral evidence.

Three of the tuffs (fig. 13) are exposed along Collier
Canyon Road, along the flank of Highland syncline
(Oestreich, 1958) (10c. 63, 63A—C).

The tuff at the base of the Highland syncline section
(10c. 63A) is unsorted and contains pumice lapilli with
some angular lithic fragments. This unit, about 2 m
thick at most, is probably the peripheral part of an
extensive ash flow. The other two tuffs in this section
(10c. 63B, C) are reworked pumice-lapilli tuffs and tuf-
faceous sediments. The exposed thicknesses of these
tuffs and tuffaceous sediments range from about 1 to 2
m, but the units are probably thicker. These three tuffs
(loc. 63A—C) are correlated with the Pinole Tuff (loc.
52A—C) on the basis of rapid-scan data. A fourth and
youngest tuff is exposed farther west, about 1 mile east
of Danville, stratigraphically far above the other tuffs
in the area (loc. 5). It is a massive very fine grained
biotite-hornblende vitric tuff, about 1 m thick, and is
probably a product of direct ash fall. The minor- and
trace-element composition of this tuff indicates that it
was probably erupted in the southern Cascade Range.

On the south side of Livermore Valley, in the Tesla
quadrangle, two tuffs are interbedded with the Liver-
more Gravels5 of Clark (1930) (fig. 9, locs. 31—34).
These tuffs, first mentioned by Huey (1948), are well
exposed at only one locality, a roadcut in a ridge be-
tween Arroyo Mocho and Arroyo del Valle. The lower
tuff is approximately 3 m thick, the upper about 2 m
thick. The tuffs are separated by a zone of tuffaceous
sediments approximately 8 m thick. The tuffs were de-
posited by water: They are well stratified and show
graded bedding, laminations, and soft-sediment de-
formation structures. A lower, massive part of both
tuffs, up to about 30 cm thick, may be directly water-

5The dominant elastic sediments exposed here are clay and mud, with some lenses of
gravel.

REFERENCES CITED

laid ash-fall material. The lower bed is correlated with
the Lawlor Tuff on the basis of trace-element chemis-
try and petrographic criteria.

NORTHEASTERN PART OF THE STUDY AREA
(FIG. 9, LOCS. 8—11, 12—15)

Two extensive units, the Nomlaki and Putah Tuff
Members of the Tehama Formation, are interbedded
with continental deposits of the late Pliocene Tehama
Formation along the foothills bordering the west side
of Sacramento Valley.

PUTAH TUFF MEMBER OF THE TEHAMA FORMATION
(FIGS. 1, 9, Locs. 12—15)

The Putah Tuff Member (Sims and Sarna-Wojcicki,
1975) has been well described by Miller (1966). Accord-
ing to Miller, the Putah crops out almost continuously
from near Vacaville in the south to a few kilometres
south of the Yolo—Colusa County boundary, a distance
of about 64 km. The tuff is thickest (about 15 m) south
of its type locality, Putah Creek, thinning to the north
and south. The tuff is well stratified and in places con-
tains rounded hard pumice lapilli, together with detri-
tal sedimentary material, indicating that it is water
deposited or reworked.

NOMLAKI TUFF MEMBER OF THE TEHAMA FORMATION
(FIGS. 1, 9, LOCS. 8—11)

The Nomlaki Tuff Member is exposed discontinu-
ously along the western side of northern Sacramento
Valley for a distance of approximately 93 km, from
north of Nye Creek to Cottonwood Creek. This tuff has
been described by Russell (1931), Anderson and Rus-
sell (1939), Lydon (1967), and Miller (1966).

At its type locality at the former headquarters of the
old Nomlaki Indian Reservation, about 6 miles north-
east of Paskenta, the tuff is approximately 4 m thick
but elsewhere ranges in thickness from about 1 m to
about 30 In.

On the basis of its texture, sorting, lack of bedding,
and absence of any lateral gradation in particle size,
Russell (1931) concluded that the Nomlaki was pro-
duced by an ash flow that had its source to the east in
the Mount Lassen area, where several exposures of its
presumed correlative were found interbedded with the
late Pliocene Tuscan Formation.

On the Geologic Map of California (Ukiah Sheet,
Jennings and Strand, 1960; Santa Rosa Sheet, Koenig,
1963, scale 1:250,000) the Putah is shown as the Nom-
laki. However, Miller (1966) has concluded that the
two tuffs are different on the basis of refractive index of
glass and feldspar composition, conclusions that are

 

29

here confirmed by trace- and minor-element chemistry
of the glasses in the tuffs.

REFERENCES CITED

Anderson, C. A., 1936, Volcanic history of Clear Lake area, Califor-
nia: Geol. Soc. America Bull., v. 47, p. 629—664.

Anderson, C. A., and Russell, R. D., 1939, Tertiary formations of
northern Sacramento Valley, California: California J our. Mines
and Geology, v. 35, no. 3, p. 219—253.

Bartow, J. A., and Addicott, W. D., 1971, Revised age of Merced(?)
Formation of Sonoma County: Geol. Survey Research, in US.
Geol. Survey Prof. Paper 7 50—A, p. A47.

Bartow, J. A., Sarna-Wojcicki, A. M., Addicott, W. 0., and Lajoie, K.
R., 1973, Correlation of marine and continental Pliocene de-
posits in northern California by tephrochronology [abs]: Am.
Assoc. Petroleum Geologists Bull., v. 57, no. 4, p. 769.

Becker, G. F., 1888, Geology of the quicksilver deposits of the Pacific
slope: U.S. Geol. Survey Mon. 13, 486 p.

Borchardt, G. A., Aruscavage, P. J., and Millard, H. T., Jr., 1972,
Correlation of the Bishop ash, a Pleistocene marker bed, using
instrumental neutron activation analysis: J our. Sed. Petrology,
V. 42, no. 2, p. 301—306.

Brice, J. C., 1953, Geology of Lower Lake quadrangle, California:
California Div. Mines Bull. 166, 72 p.

Clark, B. L., 1930, Tectonics of the Coast Ranges of middle Califor-
nia: Geol. Soc. America Bull., v. 41, no. 4, p. 747—828.

1943, Notes on California Tertiary correlation, in Geologic
formations and economic development of the oil and gas fields of
California: California State Div. Mines Bull. 118, p. 187—191.

Dibblee, T. W., J r., 1966, Geology of the Palo Alto quadrangle, Santa
Clara and San Mateo Counties, California: California Div.
Mines and Geology, Map Sheet 8, scale 1:62,500.

Evernden, J. F., Savage, D. E., Curtis, G. H., and James, G. T., 1964,
Potassium—argon dates and the Cenozoic mammalian chronol-
ogy of North America: Am. Jour. Sci., v. 262, p. 145—198.

Flanagan, F. J ., 1969, Survey standards—II, First compilation of
data for the new U.S.G.S. rocks: Geochim. et Cosmochim. Acta,
v. 33, p. 81—120.

Fleisher, Michael, 1969, US. Geological Survey standards—I, Addi-
tional data on rocks G—1 and W—l, 1965-1967: Geochim. et Cos-
mochim. Acta, v. 33, p. 65—79.

Gilbert, N. J ., 1969, Chronology of post-Tuscan volcanism in the
Manton area, California: California Univ., Berkeley, M.S.
thesis, 72 p. ’

Hall, N. T., 1965, Petrology of the type Merced group, San Francisco
Peninsula, California: California Univ., Berkeley, M.S. thesis,
127 p.

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30 CORRELATION OF LATE CENOZOIC TUFFS, COAST RANGES, CALIFORNIA

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7 g ”t AW:

The Roberts Mountains Formation,
a rogional stratigraphic study with
emphasis on rugose coral distribution

 

 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 973

 

 

 

The Roberts Mountains Formation,
a regional stratigraphic study with
emphasis on rugose coral distribution

By CHARLES W. MERRIAM and EDWIN H. MCKEE
With a seetion on Conodonts, by JOHN W. HUDDLE

 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 973

A study ofstratigrapliy, faeies, and

coral distribution in the middle Paleozoic

(Silurian and Devonian) limestone belt of
the central and southwestern Great Basin

 

 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1976

UNITED STATES DEPARTMENT OF THE INTERIOR
THOMAS S. KLEPPE, Secrelm‘)‘

GEOLOGICAL SURVEY

V. E. McKelvey, Director

Library of Congress Cataloging in Publication Data

Merriam, Charles Warren, 1905—
The Roberts Mountains Formation.

(Geological Survey Professional Paper 973)

Bibliography: p. 43-45.

Includes index.

Supt. of Docs. no.: I 19.162973

1. Geology,Stratigraphicisilurian. 2. Geology,Stratigraphichevonian. 3. Rugosa. 4. Geology——Nevada. 5. Geology!

California. I. McKee, Edwin H., joint author. ll. Huddle, John Warfield, 1907— joint author. 111. Title. IV. Series;
United States Geological Survey Professional Paper 973.
QE661.M45 551.7'3'0979 76—608307

 

For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, DC. 20402
Stock Number 024—001—02893—0

CONTENTS

Page
Abstract __________________________________________________ 1
Introduction ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 1
Purpose and scope of investigation ______________________ 2
Acknowledgments ______________________________________ 2
History of investigation ________________________________ 3
Paleontologic zoning of the Great Basin Silurian and Lower
Devonian ________________________________________________ 4
Scarcity of reefs or bioherms in the Roberts Mountains For—
mation __________________________________________________ 4
Distribution of Great Basin Silurian limestone and dolomite
belts and the regional dolomite problem __________________ 6
Geographic distribution of Silurian limestones ______________ 7
Roberts Mountains Formation of the Roberts Mountains, Nev ,, 7
Type section __________________________________________ 9
Stratigraphic relations to underlying and overlying
formations ______________________________________ 9
Facies changes from limestone to dolomite ,,,,,,,,,, 10
Stratigraphic paleontology of the type section ____________ 10
Fossils of units 1 and 2 ____________________________ 10
Fossils of unit 3 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10
Age of the Roberts Mountains Formation of the type
section __________________________________________ 10
Roberts Mountains Formation of the northern Simpson Park
Mountains __________________________________________ 11
Geologic setting ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 11
Coal Canyon area ______________________________________ 11
Coal Canyon fault zone ____________________________ 11
Physical stratigraphy of the Pine Hill section ,,,,,,,, 12
Stratigraphic paleontology and age of Roberts Moun‘
tains Formation at Pine Hill ,,,,,,,,,,,,,,,,,,,,,, 13
Fossils collected within the Coal Canyon fault zone W 14
Physical stratigraphy of the Pyramid Hill section 1.“ 14
Problem ofthe Silurian-Devonian boundary at Pyramid
Hill ____________________________________________ 15
Roberts Mountains Formation, Tuscarora Mountains ,,,,,,,, 15
Physical stratigraphy of the Bootstrap Hill section ,,,,,, 16

Stratigraphic paleontology of the Bootstrap Hill section H 16
Age of the Roberts Mountains Formation at Bootstrap

Hill ________________________________________________ 1’7
Roberts Mountains Formation of the northern Monitor Range ,2 18
Physical stratigraphy __________________________________ 18
Stratigraphic paleontology and age of the Roberts Moun-
tains Formation at Copenhagen Canyon ______________ 18
Roberts Mountains Formation at Brock Canyon, Monitor
Range __________________________________________________ 19
Roberts Mountains Formation at Dobbin Summit, Monitor
Range __________________________________________________ 19
Roberts Mountains Formation at Bare Mountain ,,,,,,,,,,,, 20
Roberts Mountains Formation of the northern Toquima
Range __________________________________________________ 20
Petes Canyon window __________________________________ 22
Ikes Canyon window __________________________________ 22
June Canyon sequence ____________________________ 22

 

Page
Roberts Mountains Formation of the northern
Toquima Range—Continued
Ikes Canyon window
Mill Canyon sequence ______________________________ 22
August Canyon sequence __________________________ 23
Northumberland window ______________________________ 23
Roberts Mountains Formation in the Toiyabe Range __________ 23
Callaghan window ____________________________________ 24
Dry Creek area ________________________________________ 24
Point of Rocks and Straight Canyon ____________________ 24
Pablo Canyon area ____________________________________ 25
Roberts Mountains Formation in the Shoshone Mountains -u- 25
Silurian and Lower Devonian limestones of the northern Inyo
Mountains, Calif ____________________________________ 25
Mazourka Canyon ____________________________________ 25
Vaughn Gulch Limestone __________________________ 25
Physical stratigraphy __________________________ 25
Stratigraphic paleontology ______________________ 26
Age __________________________________________ 27
Sunday Canyon Formation ________________________ 28
Age __________________________________________ 28
The Silurian—Devonian boundary in central Nevada __________ 28

An appraisal of stratigraphic and age values of rugose corals and
associated fossils, with description of previously unknown

key Rugosa __________________________________________ 29
Rugose corals of special stratigraphic value ______________ 29
Silurian nondissepimented Rugosa __________________ 29
Family Kodonophyllidae ________________________ 29
Subfamily Kodonophyllinae Merriam ________ 30
Subfamily Mycophyllinae Hill ______________ 30
Family Streptelasmatidae Nicholson __________ 30
Family Stauriidae Edwards and Haime __________ 31
Family Tryplasmatidae Etheridge ______________ 31
Family Pycnostylidae Stumm __________________ 31
Compact cerioid Pycnostylidae of Silurian limestone
facies __________________________________________ 32
Dissepimented Rugosa of the Great Basin Silurian
limestone facies ______________________________ 32
Family Spongophyllidae Dybowski ______________ 32
Family Endophyllidae Torley __________________ 34
Family Chonophyllidae Holmes ,,,,,,,,,,,,,,,, 36
Family Kyphophyllidae Wedekind ______________ 36
Family Calostylidae Roemer ____________________ 37
Family Lykophyllidae __________________________ 37
Fossils associated with rugose corals in Great Basin Silu-
rian limestones __________________________________ 37
Dasycladacean algae as indicators of the Silurian "A, 38
Conodonts of the Roberts Mountains Formation by
John W. Huddle ________________________________ 38
Locality register of major fossil localities in the Roberts Moun-
tains Formation and correlative strata ____________________ 39
Selected references ________________________________________ 43
Index ____________________________________________________ 47

IV

PLATE 1.
2
3
4
5.
6
7
8
9.

10.

11.

12

FIGURE 1.

2.
3.

TABLE 1.

CONTENTS

ILLUSTRATIONS

[Plates follow index]

Stylopleura and Pycnostylus.

. Stylopleura and Pycnostylus.
. F letcheria and Tryplasma.
. M ucophyllum and Kodonophyllum.

Tonkinaria, Kyphophyllum, Kodonophyllum, and Brachyelasma.

. Spongophyllum, Carlinastraea, and Australophyllum.
. Carlinastraea, Chonophyllum, and Calostylis?
. Carlinastraea and Australophyllum.

Kyphophyllum and Chonophyllum.
Verticillopora, Cladopora, Fauosites, Kyphophyllum, Ketophyllum, and Hercynella.
Verticillopora, Kozlowskiellina, H omoeospira, Dicoelosia, Plectatrypa?, and Gypidula.

. Coelospira, F ardenia, Kozlowskiellina, Conchidium, Cyathophylloides, Brachyelasma, and lycophyllid.

Page

Index map of part of Great Basin showing distribution of the Roberts Mountains Formation and correlative formations in
the intermediate limestone belt in Nevada and California ________________________________________________________ 8
Geologic map of the Coal Canyon area, northern Simpson Park Mountains _____________________________________________ 12

Sketch map of the northern Toquima Range showing Paleozoic sequences that contain Silurian rock in separate thrust sheets“ 21

Page
Characteristic fossils of the Great Basin Silurian coral zones _________________________________________________________ 5

. Occurrence chart of conodont species collected from Silurian and Lower Devonian formations in central Nevada __________ 40

THE ROBERTS MOUNTAINS FORMATION, A REGIONAL

STRATIGRAPHIC STUDY WITH EMPHASIS

ON RUGOSE

CORAL DISTRIBUTION

By CHARLES W. MERRIAM and EDWIN H. lVlCKIiE

ABSTRACT

A large part of the Silurian and the base of the Devonian Systems
are represented in the central and southwestern Great Basin by
limestones of the Roberts Mountains and the Vaughn Gulch Forma—
tions. In Silurian time the Great Basin region was inundated by
northward—trending shelf seaways of three wide facies belts: the
eastern regional dolomite belt which bordered the ancient land mass
on the east, the intermediate limestone belt here dealt with, and on
the west, a chert-shale-graywacke belt with some volcanic rocks that
extends into the Pacific Border province, best represented in south-
eastern Alaska. Studies of rugose corals show that each of the three
belts has distinctive corals and associated fossils not yet found in the
other belts; biofacies differences greatly complicate geologic correla-
tion across the facies boundaries.

The Roberts Mountains Formation, mainly limestone, calcareous

shale, and some dolomitic limestone, is widely distributed in the

central Great Basin, where it has been mapped from the Tuscarora
Mountains on the north to the Toquima and Toiyabe Ranges on the
south and west. It is known to be present as far north as south—
central Idaho but has been little studied in this region. The Vaughn
Gulch Limestone and its lateral shaly graptolitic facies, the Sunday
Canyon Formation, occur to the southwest in the Inyo Mountains.
Thick eastern regional dolomite facies rocks such as the Lone Moun—
tain Dolomite and the Laketown Dolomite come into close proximity
to, or intertongue with, limestone of the middle belt in a few areas
such as the Roberts Mountains, Bare Mountain near Beatty, Nev.,
and the Inyo Mountains. In a number of places such as in the Tusca-
rora Mountains, the Simpson Park Mountains, the Roberts Mountains,
the Monitor Range, and the Toquima Range, the Roberts Mountains
limestone has been subdivided into additional lithologic units given
new formational names. These include the Windmill Limestone of
Johnson, the McMonnigal Limestone, and the Wenban Limestone.
The names Masket Shale and Gatecliff Formation were used by Kay
for rocks in the Toquima and Toiyabe Ranges that closely resemble
parts of the Roberts Mountains Formation elsewhere. In most areas
the basal part of the formation is a black cherty limestone or dolo-
mite followed upward by calcareous shaly laminated and platy lime-
stone that bears graptolites. The upper part consists of thin—bedded
laminated limestone and slabby thicker bedded allogenic limestone
. and dolomitic limestone yielding corals, brachiopods, and calcareous
algae as well as graptolites.

The Silurian-Devonian boundary lies within this upper interval.
This boundary, defined on the basis of graptolites in the standard
time scale, is more than 100 m lower than that based on rugose
corals and calcareous algae that uses as reference the well-known
section in Gotland, Sweden.

INTRODUCTION

The name Roberts Mountains Formation applies to

 

limestones, mostly argillaceous, and some dolomitic
marine strata occupying a northerly oriented linear
belt within the central and west-central Great Basin.
Diverse fossil assemblages from many localities indi-
cate that in the time-stratigraphic sense this formation
probably makes up much of the Silurian and the bot-
tom of the Devonian Systems as represented in the
Great Basin of the western United States. The
Silurian-Devonian boundary lies‘within the upper or
even upper middle part of the formation. A reexamina-
tion of field relations of the fossil-bearing strata and a
review of fossil comparisons with those of standard
columns for the Silurian and Devonian Systems indi-
cates that the standard time scale based on graptolites
includes rocks in the Great Basin that are somewhat
older than rugose corals would suggest.

The Roberts Mountains Formation is bordered on
the east by dolomite that prevails throughout the
east-central and eastern Great Basin. On the west,
where the boundary is theoretical, the limestones are
inferred to grade into shale, graywacke, coarse argil-
laceous rocks, volcanic rocks, and subordinate lime-
stone of the Pacific border province (Merriam, 1973a).
Paleogeographically, three subparallel northward-
trending depositional facies belts are definable where
the southwest Cordilleran geosynclinal seaways of
middle Paleozoic (Silurian and Devonian) time crossed
what is today the Great Basin. From east to west these
belts are: the eastern dolomite belt, the intermediate
limestone belt, and the western or Pacific Border
graywacke belt. The transition from the dolomite to
limestone belt passes through the classical facies of
platform margin carbonate deposition. Limestones of
the intermediate limestone belt persist to the south-
west margin of the Great Basin, where they are repre-
sented by the Vaughn Gulch Limestone in the north-
ern Inyo Mountains, Calif.

As rugose corals are among the diagnostic fossils of
the Roberts Mountains Formation, this study was in-
spired by the need for dependable stratigraphic se-
quences in deformed Great Basin Paleozoic rocks to

1

2 ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

be used in conjunction with Rugosa and their strati-
graphic ranges. Studies of Great Basin rugose corals
and associated fossils have demonstrated marked bio-
facies differences between the three facies belts that
make difficult interbelt paleontologic correlation.

PURPOSE AND SCOPE OF INVESTIGATION

In Silurian and Devonian limestone areas of the
central and southwest Great Basin, geologic mapping
within the past 10 years necessitates restudy and re-
definition of the Roberts Mountains Formation and
correlative units, including those of contiguous dolo-
mite areas. Among primary objectives, this effort en-
tails search for realistic vertical and lateral formation
boundaries which reflect depositional facies relations.
The physical stratigraphy depends upon refinement of
geologic mapping and paleontologic correlation as
background, and the biostratigraphy presented here
leans heavily upon zonation of the Great Basin Silu-
rian and Devonian by means of corals and associated
megafossils (Merriam, 1973a, b, c; 1974). In this coral
work, the Gotland, Sweden, Silurian yardstick is the
primary standard of comparison and geologic correla-
tion. In some sections a wide gap exists between the
accepted Silurian-Devonian boundary as determined
by the graptolite and conodont specialists and the
placement of the boundary by the cdral specialist. For
example, the Monograptus uniformis Zone at the base
of the Devonian falls as low as the middle part of the
Silurian delimited by means of corals. Explanations
are sought for these discrepancies.

The systematic and descriptive paleontology of many
rugose corals listed in this report is treated in recent
works (Merriam, 1973a, b). A paleontologic appendix
covers stratigraphically relevant but undescribed
megafossils and evaluates certain little-known rugose
coral groups, calcareous algae, and conodonts for age
determination, correlation, and biostratigraphy. As no
megafossils were found by the geologists who mapped
many exposures of the Roberts Mountains Formation,
age designations of these structurally and stratigraph—
ically isolated beds are based on conodont studies.
Twelve plates illustrate some of the distinctive
megafossils of this formation.

A detailed report by T. E. Mullens (unpub. data,
1975) covers comparative lithology, sedimentology,
and petrology of the Roberts Mountains Formation and
its economic potential as a gold-bearing formation.

Briefly touched upon herein are the complex en-
vironmental and geochemical aspects of the multi-
faceted dolomite problem bearing upon the complete
change frOm marine limestone to pervasive diagenetic
dolomite passing into’the eastern dolomite belt.

 

 

In recent years the Roberts Mountains Formation

has assumed economic importance as host rock for the
Cortez and Carlin gold ores of central Nevada. As a
result, the known extent of the formation has been
intensively explored and prospected. Some economic
aspects of ore search, geochemistry, and geophysical
prospecting are treated in other reports (T. E. Mullens,
unpub. data, 1975).

ACKNOWLEDGMENTS

Geologic mapping used in this report includes re-‘
sults of D. C. Ross in the northern Inyo Mountains, ‘
Calif, Harold Masursky and Jonathan C. Matti in the ‘
northern Simpson Park Mountains, and J. H. Stewart .
in the central Toiyabe Range and Shoshone Moun— .
tains, Nev. Efforts by these geologists toward clarify- ‘

ing geologic structure and stratigraphy have been ‘

most helpful. Detailed geologic mapping in the south-

ern Tuscarora Mountains, Nev., by J. G. Evans, sheds ‘

new light on the source beds of earlier fossil collections
made in the Bootstrap mine area before large—scale t0-
pographic maps made accurate field location possible.

These especially well preserved silicified fossils col- ,
‘lected by R. J. Roberts and associates near the

Bootstrap mine in the years 1954 to 1958 first demon-
strated the northward continuation of the Roberts
Mountains Formation beyond the Humboldt River
Valley. Rugose corals in Coal Canyon, Simpson Park
Mountains, were first collected by R. J. Roberts; at a
later time, Silurian and Devonian coral collections by
J. G. Johnson and A. J. Boucot were contributed for use
in this study. Collections of corals by Leland Cress at
Maggie Creek, Tuscarora Mountains, revealed the
presence of Silurian and Early Devonian corals in this
area. A well-preserved colonial rugose coral from the
Sunday Canyon Formation in Mazourka Canyon col-
lected by C. H. Stevens of San Jose State University is
acknowledged with thanks. Jonathan C. Matti made
many helpful suggestions on the manuscript and re-
viewed the conodont section.

Graptolite identifications accompanying this report
are the work of W. B. N. Berry.

Many detailed stratigraphic sections have been
measured across the Roberts Mountains Formation
throughout its known extent by T. E. Mullens. Litho-
logic data from these sections have been employed in
the present report, especially at Bootstrap Hill in the
Tuscarora Mountains.

J. W. Miller ably assisted Merriam in detailed geo-
logic mapping of the Coal Canyon area and other parts
of the northern Simpson Park Mountains. In the To-
quima Range all the detailed geologic mapping provid-
ing the basis for stratigraphic conclusions in that area
is the work of E. H. McKee. Earlier geologic mapping

INTRODUCTION V ’ 3

of parts of that range was done by Kay and Crawford
(1964).

All fossil photographs are the work of Kenji
Sakamoto.

HISTORY OF INVESTIGATION

Silurian limestones were first studied in the Roberts
Mountains by Merriam while he searched for the base
of the Devonian System in that area (Merriam, 1940,
p. 11). On the northwest side of Roberts Creek Moun-
tain, the lowest beds in the Nevada Formation iden-
tified in 1940 contain the Acrospirifer kobehana fauna
of Early Devonian age and appeared at that time to
conformably overlie massive dolomites identified as
the Lone Mountain Dolomite of supposedly, but as yet
unestablished, Silurian or perhaps Early Devonian
age. Comparison with the Lone Mountain type section
18 miles (29 km) to the south revealed significant
lithologic differences. Whereas no limestone is present
in the Upper Ordovician or Silurian at Lone Mountain,
beneath the Lone Mountain Dolomite at Roberts Creek
Mountain is a thick fossiliferous Silurian sequence of
limestones and some dolomite named at that time the
Roberts, Mountains Formation by Merriam (1940).
This unit occupied the stratigraphic interval between
the underlying limestone and dolomite of the Hanson
Creek Formation and the blocky light-gray dolomite
interpreted by Merriam (1940) as the higher part ofthe
Lone Mountain Dolomite. Comparison of the sections
at Lone Mountain and Roberts Creek Mountain led to
extension by Merriam (1940) of the name Roberts
Mountains FOrmation to the dark dolomite beneath
the type Lone Mountain Dolomite in accord with the
view that this was a dolomite facies of the Roberts
Mountains Formation. Later mapping in the Roberts
Mountains by Winterer and Murphy (1960) clearly
demonstrated the lateral equivalence by the inter-
tonguing of the Roberts Mountains Formation and the
Lone Mountain Dolomite. In a recent study of the stra-
tigraphy and paleontology of the Lone Mountain
Dolomite at Lone Mountain (Merriam, 1973b), the
dark dolomite previously referred to as dolomitic
Roberts Mountains Formation has been redesignated
as part of the Lone Mountain Dolomite because it was
considered desirable to retain the formational term
Roberts Mountains for a predominantly limestone unit
only.

Above the type section of the Roberts Mountains
Formation, at Roberts Creek Mountain, the saccharoi-
dal Lone Mountain dolomites have yielded no fossils;
the possibility remains that the uppermost part of this
thick dolomite sequence may correlate with the finer
textured Beacon Peak Dolomite Member of the Nevada
Formation.

 

Reconnaissance geology of the northern Monitor
Range by Merriam and Anderson (1942) made known a
southerly extension of the Roberts Mountains Forma-
tion. In Copenhagen Canyon, for example, the Silurian
and Lower Devonian were found to be represented by
thinly laminated calcareous shaly rocks carrying grap-
tolite faunas and thicker graded beds of bioclastic
limestone. Kay and Crawford (1964) recognized the oc-
currence of the Roberts Mountains Formation (called
by them the Masket Shale) farther southwest in the
Toquima Range, where various limestone and argil-
laceous limestones occupy parts of several separately
mappable thrust plates. More recent detailed mapping
in that area by McKee (1976) sheds additional light
upon the facies, paleontology, and correlation of the
Roberts Mountains Formation in the Toquima Range.

Northwest of the type area, the Roberts Mountains
Formation was extended into the northern Simpson
Park Mountains by R. J. Roberts and associates during
reconnaissance geologic mapping of northern Eureka
County in 1954—58. Knowledge of these rocks was
further advanced by Winterer and Murphy (1960) and
Johnson (1965). R. J. Roberts and associates extended
the distribution of the Roberts Mountains Formation
northward into the Tuscarora Mountains and Elko
County during the Eureka County .mapping program.
Since 1967, parts of the southern Tuscarora Mountains
near Carlin, NeV., have been mapped in detail by the
US. Geological Survey. Where the formation is locally
gold bearing, much has been learned of the complex
structure and stratigraphy; geochemical and geophysi-
cal investigations have been carried out by economic
geologists in connection with drilling exploration be-
yond the currently productive belt

Geologic mapping of the Cortez quadrangle by Gil-
luly and Masursky (1965) and the Mount Lewis area
by Gilluly and Gates (1965) extended the known occur-
rence of the Roberts Mountains Formation into the
Cortez Mountains and northern Shoshone Range. The
formation has subsequently become economically im-
portant as a gold ore host in that vicinity.

In 1968 the economic potential of the Roberts Moun—
tains Formation as a source of gold in north-central
Nevada became sufficiently evident tojustify a special
study by the US. Geological Survey. The lithologic and
stratigraphic, aspects of this study‘were undertaken by
T. E. Mullens, who worked with quadrangle mapping
parties and geochemists in economically promising
areas. Mullens has carried out detailed section meas-
urement and studies of sedimentary petrology in many
areas, including those where mapping was in progress
(Mullens, unpub. data, 1975). _

Mapping of the Horse Creek Valley quadrangle in
the northern Simpson Park Mountains by Harold

4 ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

Masursky, begun about 1960, carried eastward the
geology begun by Gilluly and Masursky in the adjoin-
ing Cortez quadrangle (1965). A progress map was
transmitted by Masursky in 1971 for the use of the
writers in conjunction with the Paleozoic stratigraphy.
As the Horse Creek Valley quadrangle includes the
Coal Canyon section, first fully described by Johnson
(1965) and probably the best reference section for the
Roberts Mountains Formation, parts of it have been
remapped in more detail by Merriam and Miller, a
work still in progress.

Interest in southwestern Great Basin Silurian lime-
stones as correlatives of the Roberts Mountains For-
mation developed in 1946 with geologic mapping of the
Cerro Gordo mining district, Inyo Mountains, Calif.
(Merriam, 1963). At that time it became evident that
westward and northward, the Hidden Valley Dolomite
(McAllister, 1952) changed to limestone. Section
measurement, reconnaissance geologic mapping, and
fossil collecting were begun in 1947 at Mazourka Can-
yon, where the coral genera and calcareous algae of
these Inyo Silurian beds were found to be closely allied
to those of the central Great Basin. Subsequently, Ross
(1963, 1966) carried out the refinements of detailed
geologic mapping of the northern Inyo areas. A north-
ward change of Silurian limestone into shale facies is
demonstrated by the Ross mapping.

The underlying paleontologic motivation for this
study of Silurian limestone dates from the discovery by
Merriam of well-preserved Rugosa in the Roberts
Mountains in 1933, and in the northern Inyo Moun-
tains about 1946. As general worldwide knowledge of
Silurian Rugosa progressed rapidly, coral studies lead-
ing to a provisional Great Basin Silurian coral zona-
tion were initiated by Merriam (1963), providing, to-
gether with brachiopod studies, much of the paleon—
tologic support for this contribution. Further incentive
came with the brachiopod investigations of J. G.
Johnson and A. J. Boucot, who introduced European
comparisons, and with investigations by W. B. N.
Berry of graptolites of Great Basin Silurian and Devo—
nian rocks. Conodont studies by Gilbert Klapper coor-
dinated with field studies of M. A. Murphy added a
wealth of information about the Silurian and Devonian
of central Nevada. The most modern discussion of the
formation is the study by Matti, Murphy, and Finney
(1975).

PALEONTOLOGIC ZONING OF THE GREAT
BASIN SILURIAN AND LOWER DEVONIAN

Rugose corals provide a useful means of strati-
graphic zonation in the Great Basin Silurian and De-
vonian limestone facies. These fossils, common in
nearly all the bioclastic limestones, are generally well

 

preserved and represent several genera known in the
Silurian of Gotland, Sweden; England; eastern Europe;
and Australia. Graptolites, the primary basis for sub-
dividing the world Silurian System, are abundant in
rocks of the lower part of the Great Basin Silurian and
occur at many places well into the Devonian. Great
Basin Silurian and Devonian brachiopods are well rep-
resented, and much has been done to tie their occur-
rences and stratigraphic ranges to mapped areas and
measured sections. The large dasycladacean algae of
the genus Verticillopora are especially useful in Great
Basin Silurian strata. Verticillopora ranges upward,
from Great Basin Silurian coral zone B through zone E,
apparently reaching a peak of development in coral ‘
zone D (see below). ‘

Conodonts are found through much of the Silurian
and Devonian limestone of this province and are cur— .
rently being coordinated with age determinations
based on associated megafossils.

Study of the stratigraphic distribution of Silurian
Rugosa in correlative and overlapping reference sec-
tions throughout the Great Basin makes possible a .
hypothetical fivefold zonation based on the ranges of .
species and genera. Provisional zones are designated ‘
by capital letters A through E in ascending strati-
graphic order. Gaps in the coral record within a single
reference section are filled in correlative sections to
complete the overlapping composite zonal scheme. No
more than three coral zones have been recognized
within any one reference column; further collecting is
expected to eliminate some of these local gaps.

The five coral zones ranging in age from Early to
Late Silurian are:

Age Coral zone
Late Silurian1 E
D
Middle Silurian C
B
Early Silurian A

SCARCITY OF REEFS
OR BIOHERMS IN THE
ROBERTS MOUNTAINS FORMATION

Reef and biohermal structures occur in Silurian
marine limestone and dolomite rich in calcareous al-
gae, stromatoporoids, crinoids, and corals in many
areas throughout the world (Lowenstam, 1949). These
structures are parts of the Niagaran Series of the
Great Lakes and the Gotland of Sweden (Manten,

 

‘Age designation based on Comparison with the Gotland, Sweden, Rugosa. Coral zone E
contains rocks of Lower Devonian age based on the occurrence of Monograptus umfnrmzs,
the accepted index for lowermost Devonian in the Great Basin.

SCARCITY OF REEFS OR BIOHERMS 5

TABLE 1.—Characteristic fossils of Great Basin Silurian coral zones

 

 

Geologic Coral
age zone Rugose corals Tabulate corals Brachiopods Dasycladacean algae
Late
Silurian1 ,,,,,, E ______ Stylopleura nevadensis Merriam Orthostrophia sp. Verticillopora annulata
Stylopleura berthiaumi Merriam Schellwienella? sp. Rezak
Mucophyllum oliveri Merriam Barrandella? sp. Verticillopora cf. V.
Kodonophyllum mulleri Merriam Sicorhyncha? sp. annulata Rezak
Rhizophyllum cf. R. enorme Rhynchospirina sp.
(Oliver) Plectatrypa? sp.
Rhizophyllum sp. D Oliver Atrypa sp.
Chonophyllum simpsoni Merriam Meristella sp.
Australophyllum (Toquima-phyllum) Kozlowskiellina sp. f
johnsoni Merriam
Carlinastraea tuscaroraensis
Merriam
Kyphophyllum neuadensis Merriam
Kyphophyllum sp. c
Salairophyllum? sp.2
D ______ Brachyelasma sp. Dicoelosia sp. r Verticilfiopora annulata
Reza
Stylopleura berthiaumi Merriam Gypidula sp. r Verticillopora cf. V.
annulata Rezak
Tonkinaria simpsoni Merriam Homoeospira sp. r
Tryplasma duncanae Merriam Atrypa sp.
Carlinastraea tuscaroraensis Kozlowskiellina sp. f
Merriam
Middle
Silurian ______ C ______ Tryplasma newfarmeri Merriam
Denayphyllum denayensis Merriam
Entelophylloides (Prohexagonaria)
occidentalis Merriam
B ,,,,,, Streptelasmid corals (small) Halysites (Cystihaly- Verticillopora sp.
Brachyelasma sp. B sites) magnitubus
Ryderophyllum ubehebensis Buehler
Merriam
Pycnactis sp. K
Petrozium mcallisteri Merriam
Early
Silurian ______ A ,,,,,, Rhegmaphyllum sp. h Cladopora sp.

Dalmanophyllum sp. A

Palaeocyclus porpita subsp.
mcallisteri Merriam

Rhabdocyclus sp. d

Cyathophylloides fergusoni
Merriam

Arachnophyllum kayi Merriam

Neomphyma crawfordi Merriam

Heliolites sp.
H alysites sp.

Dicoelosia sp.
Dalmanella sp.
Atrypa sp.

 

‘Age designation based on comparison with the Gotland, Sweden Rugosa. Coral zone E contains rocks of Lower Devonian age based on the occurrence of Monagraptus uniformis,'the

accepted index for lowermost Devonian in the Great Basin.

2Salalrophyllum’.’ from uncertain stratigraphic horizon at Coal Canyon, Simpson Park Mountains, Nev, Probably from Coral zone E,

1971). The Roberts Mountains Formation, however,
shows little evidence of reefal structure, or even of
minor bioherms having initial bottom relief. In most
places, the lower part of the formation is thin and con-
sists of evenly laminated fine-grained argillaceous
limestone with no reeflike characteristics. The upper
part of the formation contains thin— to medium-bedded
bioclastic limestone as well as fine-grained thin lami—
nated beds. These rock types represent a facies that
must have formed at a moderate depth of water. Cor-
als, calcareous algae, and brachiopods, mostly frag-
mental, are fairly abundant in parts of the formation,
but they have not developed into reeflike structures;
indeed, in most places the fossils have been trans-
ported with other calcareous debris as debris flows.
At Coal Canyon, Simpson Park Mountains, deposi-

 

tional breccias may mark the vicinity of small patch
reefs or bioherms, but no inclined reef—marginal beds
or reef core rock was found. Some limestone strata of
the upper Roberts Mountains Formation in the Roberts
Mountains rich in corals and other benthonic or-
ganisms appear to represent beds and banks of very
low bottom relief, but many are thick allodapic beds
deposited in basins or on a gentle slope at greater
depths than reef formation and below wave base.

Stromatoporoids contributed much of the material
toward the building of reefs in the Niagaran of Illinois
(Lowenstam, 1949) and in the Silurian of Gotland,
Sweden (Manten, 1971). In the coral-rich Roberts
Mountains Formation limestones, stromatoporoids,
though present, apparently were not important as reef
builders.

6 ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

DISTRIBUTION OF GREAT BASIN
SILURIAN LIMESTONE AND
DOLOMITE BELTS AND THE REGIONAL
DOLOMITE PROBLEM

Areal distribution of Great Basin Silurian carbonate
rocks in contrasting lithologic belts such as the inter—
mediate limestone and eastern dolomite belts leads to
paleogeographic speculation and review of the multi-
faceted unsolved problems of the origin of marine
dolomite. It is not a purpose of this report to enter into
the complexities of geochemical and metasomatic
change. Dolomites of the eastern belt certainly fall in
the category of regional dolomite of diagenetic origin
as contrasted with localized hydrothermal or meta-
morphic dolomites. In several mining districts of this
province, the hydrothermal type locally forms very
large bodies that may easily be confused with the
diagenetic type (Hewett, 1931, p. 57—58). Nonetheless,
some interpretation is appropriate in explaining the
discrete lithologic and paleogeographic boundary zone
separating the eastern dolomite from the intermediate
limestone belt within which the Roberts Mountains
Formation is found.

In relation to regional dolomites of vast extent like
the eastern dolomite belt, we may seek explanation of
its lateral boundaries from various fields of study in-
cluding paleogeography, paleobiology, geochemistry,
marine environment and the sources of magnesium in-

troduced to produce the double carbonate mineral i

dolomite. We may ask: how or why does proximity to
the subdued Silurian land mass on the east favor
diagenetic dolomitization while offshore limestones
remain normal marine limestone?

The dolomite question has been reviewed by many
workers, including Van Tuyl (1916a, b), Steidtmann
(1911, 1917), Skeats (1918), Fairbridge (1957), and,
more recently many authors represented in Pray and
Murray (eds. 1965), Bathurst (1971), and Hsii and
Schneider (1973). Beyond doubt, the Laketown and
Lone Mountain Dolomites, like the Niagaran of the
continental interior—nearly continuous dolomites that
cover thousands of square miles and are locally more
than a thousand feet thick—fall into a regional cate—
gory.

It has long been known that the amount of regional
dolomite increases downward through the geologic sys-
tems from Holocene to Precambrian (Fairbridge, 1957)
and (Daly, 1907, 1909). The Silurian is one of the sys-
tems containing much continuous regional dolomite in
North America, as in the Great Basin and the conti-
nental interior.

Ulrich and Schuchert (1902) were perhaps the first
to note that certain extensive regional dolomites bor-
der upon ancient shorelines. In the Great Basin Silu-

 

rian, the regional dolomite belt lies between the old
subdued landmass on the east and the intermediate
limestone on the west. Farther west the Pacific border
graywacke belt, through its extent from northern
California to Alaska, is not known to include dolomite
of the diagenetic type. Fossil and lithologic evidence
indicates that the Silurian eastern dolomite and the}
intermediate limestone both represent shallow marine
environments, possibly with some deepening where
limestones appear, especially the allogenic graded
types, and further deepening into graptolitic fine-
grained and laminated beds. The western limit of
dolomite, here the Lone Mountain Dolomite, was the
western limit of reef development that migrated west—
ward by normal landward carbonate accumulation typ-
ical of all large carbonate-producing regions. The gen-
erally regressive series of carbonate rocks that were
deposited in the Great Basin during the lower and
middle Paleozoic are strong evidence for the landward
accumulation of carbonate sediment (and hence retreat
of the sea) produced in the shallow shelf seas. Very
extensive tidal flats and mud shoals behind or east of
the Lone Mountain reef are the present site of the re-
gional dolomites we see today.

Studies of rugose corals suggest that the Lone Moun-
tain and Laketown Dolomites contain marine faunas
differing in biofacies from those of limestones in the
Roberts Mountains Formation (Merriam, 1973a). This
does not, however, imply that the dolomite facies was
initially deposited as dolomite sediment by direct
chemical precipitation. Other ecological factors must
be sought: for example, differences of water tempera-
ture, depth, salinity, and food supply. Fossils are 10-
cally abundant in the dolomites, but unless silicified
early, that is, prior to dolomitization, they are de-
stroyed by dolomitic recrystallization. Among the fac—
tors to be considered is the proximity to the shoreline,
where extensive mudflats were doubtless very broadly
exposed at low tide to bring about diurnal evaporative
concentration to produce brines. Percolation of the
magnesium-rich brine into the carbonate sediments
may have taken place by reflux action seaward from
the mudflats as suggested by Adams and Rhodes (1960)
or by capillary transfer through the sediments as
suggested by Friedman and Sanders (1967). Another
theory suggests that drainage from the landmass on
the east introduced additional magnesium as well as
calcium to become available for the additive process of
dolomitization. Movement of the carbonate-bearing
ground water upward through the nearshore mud-
banks probably was facilitated by evaporation across
the banks and the subsequent pumping action created
by this system (Hsii and Siegenthaler, 1969, and Hsii
and Schneider, 1973). Westward toward the boundary

THE ROBERTS MOUNTAINS, NEVADA 7

zone between the eastern dolomite belt and the inter-
mediate limestone belt, the magnesium calcium ratio
became too low for dolomitization because of the ab-
sence of shallow water evaporative sites and less ex-
tensive tidal mudflats.

It is possible that the organic community that popu-
lated the nearshore flats (now the dolomitic belt) pro-
duced proportionally more high-magnesium calcite or
even some dolomite by their biochemical processes,
thereby fixing a large amount of magnesium into the
system. In slightly deeper water with greater circula-
tion, a different assemblage of organisms produced
mainly calcite, and limestone was the carbonate depos-
ited. Sediments in this region were not dolomitized be-
cause magnesium was not available.

Concentration of brine magnesium carbonate by
evaporation at low tide on mudfiats as a major factor in
the dolomitization process has been studied by a
number of investigators under a theory involving su-
pratidal mudflats to which marine waters are added
only occasionally during exceptionally high springtides
and heavy storms. Greater concentration of magne-
sium in the brines comes about by evaporation and by
the solutions percolating downward and seaward (re-
flux) to bring about metasomatic dolomitization of un-
derlying carbonate muds and sands already containing
magnesium in organically secreted calcite matrices. In
such evaporative environments, gypsum and other
salines should also be represented. Within the past 10
years, penecontemporaneous dolomites attributed to
supratidal environments have been found in the Per-
sian Gulf (Illing and others, 1965, Hsii and Schneider,
1973, DeGroot, 1973), in the Netherlands Antilles
(Deffeyes and others, 1965). These discoveries illus-
trate the local hydraulics and geochemistry of contem-
porary dolomite formation on a fairly large scale, but
they do not appear to provide the entire key to resolv-
ing the problem of vast regional dolomites like those of
the Great Basin Silurian.

In reality, dolomitization on a regional scale as in
the eastern Great Basin is probably the product of all
the mechanisms suggested. Addition of magnesium
concentrated by evaporative processes on the inshore
tidal flats, magnesium-rich solute introduced from the
land drainage as well as crystalline dolomite clastic
debris introduced from exposed and eroding dolomite
formations (for example, the Ordovician Bighorn
Dolomite), and redistribution of magnesium taken
from sea water by organisms and deposited as high
magnesium calcite must all be significant factors.

GEOGRAPHIC DISTRIBUTION OF
SILURIAN LIMESTONES

Strata of the Silurian intermediate limestone belt

 

are known over a distance of about 325 miles (525 km)
in a south-southwesterly direction from the Tuscarora
Mountains of Elko County, northern Nevada, to the
northern Inyo Mountains, southeastern California
(fig. 1). The width of the slightly sinuous limestone
band can only be estimated, but in most places, it is
more than 50 miles (80 km) wide and may exceed 90
miles (145 km) before passing entirely into the west-
ern, predominantly shale-graywacke facies. Whereas
the west boundary is inferred at this time because of
lack of exposures and subsurface geologic data, the
east boundary can be delimited within much narrower
limits of error in many places, as, for example, at
Roberts Creek Mountain, Bare Mountain near Beatty,
Nev., and the Inyo Mountains, Calif, where the lime—
stones and dolomites either intertongue, are interbed—
ded, or crop out within a few miles of each other.

The intermediate limestone belt has been mapped and
studied in detail in the Roberts Creek Mountains, the
northern Simpson Park Mountains and Cortez Moun-
tains, the Copenhagen Canyon area of the Monitor
Range, the northern Toquima Range, and the northern
Inyo Range. Outcrop areas where the geologic mapping
is of a reconnaissance nature, or where the strati-
graphic work has been confined to section measure-
ment, are the Bootstrap mine area of the Tuscarora
Mountains, Swales Mountain in the Independence
Range, the Carlin Mine and Maggie Creek area in the
Tuscarora Mountains, parts of the northern Monitor
Range, and the Wall and Pablo Canyon area of the
Toiyabe Range. A number of widely separated outcrop
areas of these limestones have been identified and sec-
tions measured, but additional mapping or strati-
graphic paleontology is needed. These areas include
the Mount Callaghan area of the Toiyabe Range; the
Ravenswood area of the Shoshone Range; areas near
Reeds and Dry Canyons, Toiyabe Range; Dobbin
Summit, Monitor Range; the Northumberland area of
the Toquima Range; Bare Mountain area near Beatty;
and occurrences north of Wells near Antelope Peak. A
comprehensive documented stratigraphic summary of
these localities and others is presented in T. E. Mullens
(unpub. data, 1975).

ROBERTS MOUNTAINS FORMATION OF
THE ROBERTS MOUNTAINS, NEV.

In the Roberts Mountains, the Roberts Mountains
Formation is exposed over a large area on the west and
northwest side of Roberts Creek Mountain, the type
area of the formation. Other outcrops occur near the
north edge of the range between Willow aand Birch
Creeks.

The Roberts Mountains Formation in its type area
includes a variety of dark-gray to bluish-gray lime-

8 ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

 

 

 
 
    
 

  

 

 

 

   
  
  

 

 

 

 

      

 

 

 

 

  
 

 

 

 

l l EXPLANATION
oLakeView OREGON I lDAHO ‘
42., _ I Roberts Mountains Formation and correlative formations
Intermediate / . . . . .+. .
. I Foss“ localities of stratigraphic importame With regard to the
I Limestone / I ._ Roberts Mountains Formation
1 Western Belt +2,5’ 5
Graywacke l E 1. Roberts Mountains Formation, type section. Roberts Creek
I _ Mountain, Roberts Mountains.
Shale Winnemu‘ica I g 2. Roberts Mountains Formation, reference section. Coal
| Belt I 4 Canyon, northern Simpson Park Range.
I ’5 3. Roberts Mountains Formation. North pediment slopes of
‘ 5 northern Simpson Park Range.
I 4. Roberts Mountains Formation. Cortez Mountains.
Pyramid Lovelock I S S. Roberts Mountains Formation. Goat Peak, Shoshone Mountains.
405 Lake I g 6. Roberts Mountains Formation. Dry Creek area, Toiyabe Range.
7. Roberts Mountains Formation. Petes Canyon window,
2 Toquima Range.
I 17‘ 1% Cree Lone Mountain 2 S, 8. Roberts Mountains Formation and Tor Limestone. June
Mtn 21 015ml“! | 3» Canyon sequence. Ikes Canyon window, Toquima Range.
Fallono I o , Oxyoke Canyon 3 I . ~ - -
OVii-ginia City I ‘Aus'mia 22 24 >| 9. Roberts Mountains Formation and McMonnigal Limestone.
A16 A7 oEly Ibex Mill Canyon sequence. Ikes Canyon Window, Toquima Range.
°Carson City I 1'56““) 828 “33.,“ Hill Hills 10. August Canyon sequence. Gatecliff Formation of Kay and
Lake I Canvon“ 1 Dobbin Summit Crawford (1964). Ikes Canyon window, Toquima Range.
Tahoe \ Walker I A l 1 1. Roberts Mountains Formation. Northumberland window,
\ “152% ‘12 13 | Toquima Range.
\ o [Manhattano l Eastern 12. Roberts Mountains Formation. Pablo Canyon area, Toiyabe Range.
ridgepd-ilfwtome / l Dolomite l 13. Roberts Mountains Formation. Clear Creek and Dobbin
o \ Summit area, Monitor Range.
38° Sonora: Mono oTonopah l Belt I 14. Roberts Mountains Formation. Brock Canyon area, Monitor Range.
0 6L } Pioche° 1 S. Roberts Mountains Formation. Bowman Creek area, Toiyabe Range.
Goldfield | 16. Roberts Mountains Formation. Point of Rocks and Straight
° ' Caliente Canyons area, Toiyabe Range.
Pahranagat 17. Roberts Mountains Formation. Ravenswood area, Shoshone
l Rm” Mountains.
\ \ I 5 1 8. Roberts Mountains Formation. Callaghan window, Toiyabe Range.
“- 19-20 Beacon Peak Dolomite Member of Nevada Formation. Southern part
no eatty E of Sulphur Spring Range.
0 n o \ +31 ; 21. Lone Mountain Dolomite, type section. Lone Mountain.
Independence Q," \ g 22. Lone Mountain Dolomite. Mahogany Hills.
Owenx $ \ i: 2 3. Lone Mountain Dolomite. Southern part of Fish Creek Range.
>14”, L, Lake Mead 24. Beacon Peak Dolomite Member of Nevada Formation. Oxyoke
(f \ \ Las Vegaso Canyon, Mahogany Hills.
36° “‘1. 2 5 Late Silurian rugose corals in limestone. Antelope Peak,
Snake Mountains.
\ 4) 2 6. Roberts Mountains Formation, reference section. Bootstrap
(3y \é‘,’ Hill, southern part of Tuscarora Mountains.
. (do '70 2 7 Roberts Mountains Formation. Maggie Creek area, southern
OEakE'Sf‘eld 04. '7 part of Tuscarora Mountains.
6'" 4', \ 28. Rabbit Hill Limestone, type section; Roberts Mountains
MIND '7 \ Formation. Copenhagen Canyon area, Monitor Range.
0 o 29. Vaughn Gulch Limestone, type area. Northern part of Inyo
120° ”8 ”GD ”4 Mountains.
30. Sunday Canyon Formation. Barrel Spring area, northern
0 25 50 75 100MILES Inyo Mountains.
31. Lime Mountain Dolomite above dark-gray limestone and
0 40 80 120 160 KI LOMETRES dolomite probably correlative with Roberts Mountains

Formation. Bare Mountain area.

FIGURE 1.—Part of Great Basin showing distribution of the Roberts Mountains Formation and correlative formations in the intermediate
limestone belt and fossil localities of stratigraphic importance with regard to the Roberts Mountains Formation. Approximate limits
of the Late Silurian—Early Devonian depositional facies belts are shown by heavy lines.

stones that are mostly thin bedded and weather in a
platy to flaggy fashion. The basal part of the formation
is thin-bedded blue-gray limestone with black chert
interbeds and tabular chert nodules. Above this in the
lower part of the formation is fine-textured thinly
laminated limestone and calcareous shale with a few
thin interbeds of coarse limestone. In the middle and
upper parts of the formation, there is a change to pre-
dominantly coarser slabby-weathering blocky beds, a
few centimetres to about 1 m thick, with partings of
shale or laminated limestone. Crinoidal debris is
abundant in these coarser beds, some of which are
crinoidal bioclastic lenses containing abundant corals
and brachiopods. As noted by Winterer and Murphy
(1960, p. 123—129), some of the thicker beds are fossil-
rich calcarenite locally revealing graded bedding. In

 

places, the platy and laminated fine-grained beds con-
tain abundant silt-size quartz granules. Coarse deposi-
tional limestone breccias or flat-cobble mud breccias
with limestone matrix are present as lenses in the
upper thicker bedded sequences.

Coarse-grained light-gray dolomitic limestone and
dolomite occur as tongues and interbeds in the upper
part of the formation; these dolomitic rocks can be
traced laterally into a continuous dolomite, called Lone
Mountain Dolomite. Silicified fossils are characteristic
throughout the formation, especially in dolomitic
limestones.

At the type area, the Roberts Mountains Formation
is overlain by the Lone Mountain Dolomite. At some
other places, it grades into sequences of laminated
limestone interbedded with thicker bedded clastic

THE ROBERTS MOUNTAINS, NEVADA 9

limestones that have been named the McMonnigal
Limestone (Kay, 1960, Kay and Crawford, 1964, and
McKee and others, 1972), the Windmill Limestone
(Johnson, 1965, Matti and others, 1975), and the Wen-
ban Limestone of Gilluly and Masursky (1965).

TYPE SECTION

The type section of the Roberts Mountains Forma-
tion is on the northwest side of Roberts Creek Moun-
tain between the south and middle forks of upper Pete
Hanson Creek. The formation is about 2,000 feet
(600 m) thick in the type section, where it occupies the
stratigraphic interval between the Hanson Creek
Formation and overlying dolomites classified here as
the Lone Mountain Dolomite. It is here about 70 per-
cent limestone, with a prominent cherty member at the
base and dolomitic limestone and dolomite interbeds or
tongues in the upper 200 m.

The Roberts Mountains Formation consists of well-
bedded laminated dark-gray to slightly bluish-gray,
platy, flaggy, and slabby limestone, dark-gray graded
bioclastic limestone, calcareous shale, and subordinate
black chert in the basal part of the formation. Most of
the chert, shale, and laminated to shaly limestones
occur in the lower part of the formation; the beds be-
come on the whole thicker, coarser textured, and more
bioclastic upward, with fewer of the laminated interca-
lations. Fossils are abundant in many horizons above
the cherty interval, those in the laminated or shaly
rocks are mainly graptolites.

In the type section, differences in lithology and
paleontology make feasible a three-unit subdivision of
the Roberts Mountains Formation as unit 1, 100 m;
unit 2, 300 m; and unit 3, 200 m, in ascending strati-
graphic order.

Unit 1.——Unit 1, a fine-textured cherty unit, is made
up of a basal chert and dolomite 1—3 m thick overlain
by fine-grained thin-bedded laminated dark-gray lime-
stone weathering platy and flaggy with shaly partings.
The limestones weather light gray. The laminae usu—
ally reveal an alternation of calcareous and argilla-
ceous or silty layers; in places, millimetre-thick limy
layers alternate with layers containing much dark-
colored matter probably composed of iron oxides with
organic substances (Winterer and Murphy, 1960, p.
123). The laminated strata include dark chert layers
and nodules elongate parallel to bedding. The distinc-
tive bluish-black chert-bearing interval of varying
thickness less than 3 m at the bottom of the formation,
is about 75 percent chert that contains subordinate un-
chertified and undolomitized limestone lenses. Upward
the chert decreases in amount, occurring in discontinu-
ous 1—5 cm layers separated by laminated limestone.
Fossils are scarce in the laminated limestone, but

 

shaly partings yield graptolites. The basal chert, rest-
ing upon the Hanson Creek Formation, which also is
cherty in many places, is a widely recognized unit of
the Great Basin Silurian. In some other areas it has
yielded large pentameroid brachiopods.

Unit 2.—Unit 2, thickest of the three units in the
type section of the Roberts Mountains Formation, is
made up of platy to fiaggy dark bluish-gray fine to
fairly coarse textured impure limestones with inter-
beds of bioclastic limestone as much as 1 m thick. Cal-
careous shaly partings and thin laminated layers sepa-
rate the thicker beds, many of which are highly fos-
siliferous (bioclastic); much of this debris is crinoidal.
The introduction of the thicker, rather coarsely clastic
crinoidal beds distinguishes unit 2 from unit 1. Scat-
tered black chert lenses and nodules are present as
high as about the middle of unit 2. In the upper part of
the unit are a few light-gray recrystallized layers that
are slightly dolomitic. Tabulate corals, pentameroids,
and other brachiopods are abundant in the many bio-
clastic beds; the rugose corals are subordinate.

Unit 3.—Unit 3 is gradational with unit 2 through
an interval wherein coarser textured crinoidal layers
containing abundant Conchidium grade upward into a
more uniformly thicker bedded sequence of light and
dark-gray, somewhat blocky-weathering limestones
that include coralline beds. About 75 m above its base,
unit 3 becomes prevailingly lighter gray and less well
bedded as it passes upward into the interbedded lime-
stone and dolomite of the upper half. The lower coral-
line beds contain large heads of colonial Rugosa of
Great Basin Silurian coral zone C. Light-gray-weath-
ering limestones in the upper middle part of unit 3
contain abundant silicified corals of Great Basin Silu-
rian coral zone D. Through the upper 122 m, bedding is
poorly defined, the weathering more blocky, and fossils
become fewer as the mixed carbonate rocks pass up-
ward into the coarser saccharoidal dolomite of the
overlying Lone Mountain Dolomite.

STRATIGRAPHIC RELATIONS TO UNDERLYING
AND OVERLYING FORMATIONS

Careful examination of the contact separating the
basal chert of unit 1 from the underlying Hanson
Creek Formation has disclosed equivocal evidence of
disconformity or angular discordance in the type sec—
tion. Fossil evidence elsewhere, as in the Tuscarora
Mountains (Berry and Roen, 1963), also suggests that
some of the earliest Silurian may not be represented at
or near the contact and hence a paraconformity exists
in this part of the section.

The upper limit of the Roberts Mountains Formation
in its type section is gradational with the Lone Moun-
tain Dolomite (Lone Mountain unit 2 at Lone Moun-

10

tain as redefined by Merriam in 1973). About 500 m of
blocky dolomite between Roberts Mountains Forma-
tion unit 3 and richly fossiliferous lower beds of the
Devonian Nevada Formation (or the McColley Canyon
Formation of Murphy and Gronberg, 1970) yielded no
fossils. Future study of the Lone Mountain Dolomite at
Roberts Creek Mountain may show that the part of it
correlates with part of the finer textured Beacon Peak
Dolomite Member of the Nevada Formation of the
Eureka district.

liv\(lll{S CHANGES FROM LIMESTONE 'I‘O DOLOMITE

A planimetric map of the upper Pete Hanson Creek
area by Winterer and Murphy (1960, p. 120, fig. 2) that
includes the type section of the Roberts Mountains
Formation illustrates the intertonguing relation of
unit 3 limestone to dolomitic beds of the Lone Moun-
tain Dolomite. Dolomitic limestones of these unit-3
tongues contain a fauna more closely related to that of
the Roberts Mountains limestone facies than to that of
the Lone Mountain dolomite facies as known in the
Eureka area (Merriam, 1973a, b). It is in Roberts
Mountains unit 3 of the type area that we find the most
clearly defined marginal interfingering of the inter-
mediate limestone belt to the eastern dolomite belt in
the Great Basin province.

STRATIGRAPHIC PALEONTOLOGY OF THE TYPE SECTION

The reference section for two of the five proposed
Great Basin Silurian coral zones (Merriam, 1973a) oc-
curs in the type section of the Roberts Mountains For-
mation, Silurian coral zones C and D in lithologic unit
3 of the formation. The other Great Basin Silurian
coral zones have not been recognized in this section.

FOSSILS ()F L‘NI’I‘S I AND 2

Poorly preserved Monograptus sp. with plain tubular
thecae occur in unit 1 and the lowermost part of unit 2
(W. B. N. Berry, written commun., 1964). Fossils pres-
ent in these lower beds are:

Massive favositids Small Conchidium-like
Cladopora sp. pentameroids
Heliolites sp. Dicoelosia Sp.
Halysites sp. Eatonia? sp.
Orthophyllum sp. Merista? Sp.
Pycnostylid Rugosa Atrypa sp.
Monograptus sp.

The characteristic Lower Silurian rugose corals of
Great Basin Silurian coral zone A which would be ex-
pected in these lower beds have not been found here;
those absent include the genera Palaeocyclus, Dal-
manophyllum, Arachnophyllum, and Cyathophyl-
loides.

 

ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

Fossils of early Middle Silurian (Great Basin Silu-
rian coral zone B) were expected in the middle to upper
beds of unit 2 but have not been found here. Rugose
coral genera present are Tryplasma, Palaeophyllum,
Diplophyllum, and Microplasma. Tabulate coral gen-
era in these beds are Aulopora, Cladopora, Heliolites,
and Halysites. In the uppermost beds of unit 2,
brachiopods are abundant, especially medium-sized
Conchidium-like pentameroids, some of which have
fine radial costae, others radial costae of medium
strength. Of the latter, one species (pl. 12, figs. 24—26)
resembles the Norwegian Conchidium mdnsteri Kiaer
as described and figured by St. Joseph (1938). This
species, reported in southern Norway Silurian zone 5b,
St. Joseph considered to be Early Silurian (Llandove-
rian). Other brachiopods abundant in higher beds of
Roberts Mountains unit 2 are the small Coelospira sp.
and Ptychopleurella sp.

FOSSI LS OF UNIT 3

Unit 3 of the Roberts Mountains Formation includes
two Great Basin Silurian coral zones, C and D, and is
the reference section for both. Coral zone C lies about
10 m above the base of unit 3 and has yielded only
corals, of which the following Rugosa are diagnostic:

Entelophylloides (Prohexagonaria) occidentalis

Merriam

Tryplasma newfarmeri Merriam

Denayphyllum denayensis Merriam
Coral zone D lies about 90 m above the base and con-
tains the following diagnostic Rugosa:

Stylopleura berthiaumi Merriam

Tonkinaria simpsoni Merriam

Tryplasma duncanae Merriam
Tabulate corals, dasycladacean algae, and brachiopods
were abundant here in a diverse biota. The following
are among the common associated fossils of coral
zone D:

Verticillopora cf. V. annulata Rezak

Dicoelosia sp. r

Gypidula sp. r

Homoeospira sp. r

Kozlowskiellina sp. f

Atrypa sp.

AGE ()1: '1‘H E ROBERTS MOL'NI‘AINS FORMA'I‘IOX
()14‘ THE 'l‘YPl-l SECTION
In the time-stratigraphic sense, the greater part, but
not all, of the Silurian System as well as the lower part
of the Devonian System, is believed to be recorded in
the 600 m of Roberts Mountains Formation of its type
section. Fossil evidence indicating the early part of
Early Silurian (Llandoverian) is lacking; the rest of
the system is present and is represented by graptolites,

THE NORTHERN SIMPSON PARK MOUNTAINS II

conodonts, and shelly fossils of Silurian age. The upper
part of the formation is Lower Devonian in age (Klap-
per and Murphy, 1974; Berry and Murphy, 1975).

The basal chert of the Roberts Mountains Formation
(bottom of unit 1), present in the type section and most
other Great Basin Silurian carbonate sections of both
limestone and dolomite, seems to be a dependable
marker unit. That it does transgress hypothetical time
planes fromplace to place has been suggested by F. G.
Poole (written commun., 1971), and his geologic evi-
dence is convincing. It has also been suggested that
there may be two or more chert sequences of different
ages at this place in the stratigraphic column of the
Great Basin (Jonathan C. Matti, written commun.,
1974). This possibility remains to be demonstrated.
The Silurian age of the basal chert has been estab-
lished in several widely separated localities. In the
northern Monitor Range at Copenhagen Canyon, the
basal chert contains fairly large pentameroid brach-
iopods of Silurian character. At Mill Canyon, Toquima
Range, a coral assemblage beneath the chert contains
Cladopora? sp., three species ofFavosites, Halysites (or
Cystihalysites), “Cystiphyllum” sp., and Brachyelasma
sp., a fauna suggesting a Silurian age. Graptolites
from the chert in the central Toquima Range were
identified by W. B. N. Berry as Climacograptus scalaris
and Climacograptus cf. C. medias; these species suggest
an Early Silurian (Early Llandovery) age. As shown by
Berry and Roen (1963), the beds in the southern Tus-
carora Mountains that are a few feet above the basal
chert marker contain graptolites of the Monograptus
riccartonensis Zone of early Wenlockian age.

Roberts Mountains unit 2 and the lower part of unit
3 up to and including Great Basin Silurian coral zone C
are provisionally classified as Middle Silurian (Wen-
lock). The lower and middle beds of unit 3, including
coral zone D, are considered to be L'ate Silurian (Lud-
lovian); the higher Ludlovian faunas of coral zone E
have not been found at the type section. The graptolite
succession on which the currently accepted Silurian-
Devonian boundary is based indicates that the upper
part of unit 3 is Lower Devonian.

ROBERTS MOUNTAINS FORMATION OF THE
NORTHERN SIMPSON PARK MOUNTAINS

GEOLOGIC SETTING

Silurian and Devonian strata are exposed along the
lower north slopes of the Simpson Park Mountains
(Horse Creek Valley quadrangle, Nevada), most of
which are blanketed by andesite and basalt flows. In
some parts of the foothill area, coarse gravel and
fanglomerate obscure the Paleozoic strata. Only that
part of the lower north slope of the range between

 

Grouse Creek and Red Hill at the northeast tip is cov-
ered in this report.

Between Grouse Creek and Red Hill, a distance of
about 11 km, the Paleozoic rocks are exposed in two
areas: the Coal Canyon area (fig. 2) on the west and the
Red Hill area on the east. Between these areas is a
wide band of volcanic rock and gravel cover. Over-
thrust chert and shale of the Ordovician Vinini Forma-
tion crop out extensively in the Fye Canyon area on the
southwest; Pennsylvanian or Permian conglomerate
and limestone is found within the area and discon-
formably overlies the older Paleozoic strata.

Between Grouse Creek and Red Hill, the Paleozoic
beds dip 200 to about 60° E.; the steeper dips are in the
vicinity of faults. Most faults have a northerly strike;
in some places, faulting has caused an apparent thick-
ening of the stratigraphic section. In general, the beds
become progressively younger eastward; the oldest ex-
posed rocks are the uppermost beds of the Hanson
Creek Formation on the west in a minor canyon half a
mile east of the mouth of Grouse Creek Canyon.
Nearly all the Silurian and Lower Devonian section is
exposed at Pine Hill and Pyramid Hill on the west.

COAL CANYON AREA

Pine Hill on the west side of Coal Canyon is under-
lain by a nearly continuous east-dipping section of
Roberts Mountains Formation truncated on the east by
the Coal Canyon fault (fig. 2). On the opposite or east
side of Coal Canyon, Pyramid Hill is largely Rabbit
Hill Limestone of Early Devonian age underlain along
the lower east slopes of Coal Canyon by the uppermost
beds of the Roberts Mountains Formation. The upper
part of the Roberts Mountains Formation here was
named the Windmill Limestone by Johnson (1965).
This unit of finely laminated fine-grained limestone
and thin- to medium-bedded clastic limestones is a rec-
ognizable formation at a number of places elsewhere in
the region.

At places along the west slope of Coal Canyon, the
Coal Canyon fault is marked by a north-south zone of
shearing and brecciation about 76 m wide. Within and
adjacent to the fault zone, the east bedding dips are
steep and locally reversed to the west. The fault strikes
about N. 5° W.; although its overall dip was not de-
termined by field observation, it is inferred to be a
high-angle normal fault with a possible steep east dip.
To the south, the Coal Canyon fault passes beneath
volcanic cover.

(10A 1. CANYON I-‘AL'IJY ZONE

Continuous measurement of the stratigraphic sec—
tion across Coal Canyon from Pine Hill through
Pyramid Hill must take into consideration a north-

12

116°38‘40”

ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

“6 37 24 EXPLANATION

 

40° 30'

COAL CANYON FAULT

 

assisted by J. W. Miller

     

Geology mapped by C.

 

Volcanic rocks

 

Rabbit Hill Limestone

 

Roberts Mountains Formation

 

L—V—JK—v—JRr—JW—J

0RDOVICIAN SILURIAN DEVONIAN TERTIARY

Hanson Creek Formation

Contact

\U.’

D Fault

Dashed where uncertain,
U, upthrown side: D, downthrown side

w. Merriam, 1970—74,
, 1969—70

—\

 

 

0 1000 2000 3000 4000 50'00 F E ET
I I I I I \22
1 00 M ETR ES
(I) 590 1090 5I Strike and dip of beds
M1334
CONTOUR INTERVAL 200 FEET . _ © .
A A Fossfl locality

FAULT

Z
O
>.
Z
<
U
.1
<
O
U

 

A». “fisfi ads...

FIGURE 2.—The Coal Canyon area, northern Simpson Park Mountains, showing

N
_ «as» 5%, §%%

7500' See Iocali 1y register

1
Approximate position of beds with
Monograptus praehercynicus
2

Approximate position of beds with
Carlinastraea and Stylopleura

7000'

wfifik
:%%% 6500 '

“Mr M
Wmml‘g

" 6000'

relations of the Roberts Mountains Formation

in the vicinity of the Coal Canyon fault.

south fault break of undetermined magnitude. The
Coal Canyon fault zone follows the steep west wall of
the canyon for a distance of 800 m. It is best shown on
the main northeast spur of Pine Hill, where its north-
south trace is marked by a coarse calcite-impregnated
limestone cataclastic breccia some 76 In wide. Minor
surfaces disclosing dip and direction of displacement
were not found at the margins of this coarse breccia.
The general trend of the breccia mass suggests that it
continues southward, mostly beneath talus, and passes
beneath a volcanic inlier in upper Coal Canyon basin
without observed displacement of the volcanic body.
The fault appears to have had a steep dip, but the di-
rection of inclination has not been determined. It is
probably a high-angle normal fault, although it might
conceivably be a thrust fault subsidiary to a fault in
upper Coal Canyon herein named the Rocky Hills
thrust. Mapping in the Pine Hill block reveals a
steepening of bedding dip as the Coal Canyon fault
zone is approached from the west. The steepened dips

are fault drag features suggesting either downward
movement of the east or Pyramid Hill block or west-
to-east displacement of strata in the west or Pine Hill
block on a low-angle thrust fault. The stratigraphic
sections on the two sides of the canyon, the Pine Hill
block on the west, the Pyramid Hill block on the east,
are dealt with separately.

PHYSICAL S'IRATIGRAI’HY OF THE PINE HILL SECTION

A nearly continuous section of Roberts Mountains
Formation is exposed in Pine Hill west of the Coal
Canyon fault. Only the uppermost beds of this section
have been disturbed within the Coal Canyon fault
zone. The Roberts Mountains Formation in the Pine
Hill block is about 450 m thick and is here considered
as having two IitholOgic units.

The lower Roberts Mountains unit of Pine Hill is
about 330 m thick; the base is black chert, 1—2 m thick,
resting with sharp contact upon thick-bedded light-
gray-weathering Hanson Creek dolomite and lime-

 

THE NORTHERN SIMPSON PARK MOUNTAINS

stone. The succeeding Roberts Mountains consists of
laminated thin-bedded platy and flaggy-weathering
dark-gray impure limestone with intercalations of cal-
careous shale or calcareous siltstone. There are a few
bioclastic limestone interbeds 5 or 6 cm thick contain-
ing brachiopods and other fossils. Graptolites are fairly
common in the laminated limestone and shaly units. In
the lower 30 m above the basal chert, there are a few
thin black chert bands and chert nodules. Lamination
is a characteristic feature of some of the thin limy beds
as in other areas of Roberts Mountains outcrop.

In the lower part of the lower 330-m interval, bio-
clastic limestone beds are few. A 1-inch, slightly
bluish-gray fine-grained limestone is crowded with
small silicified corals and brachiopods; another thin
bed with unsilicified fossils yielded a smooth medium—
sized Pentamerus-like brachiopod.

About 140 m above the formation base is a limonite
brown or reddish-stained silty sandstone bed contain-
ing abundant graptolites.

The upper 120-m unit of the Roberts Mountains
Formation in the Pine Hill block is an alternating
thick and thinly bedded fairly coarse-grained dark-
bluish-gray limestone with calcareous shaly and silty
intercalations. The lithologic change from the lower
unit to the upper unit is distinct, but not abrupt. Most
of the thicker limestone beds are bioclastic and contain
well-preserved corals and other fossils; the most abun-
dant are massive Favosites colonies. About 15 m of this
limestone in the upper half of the interval, which car-
ries a varied fauna of rugose corals and brachiopods, is
referred to as the Carlinastraea beds. Thick beds of
depositional breccia occur in the upper part of the
Roberts Mountains Formation on the east side of Coal
Canyon in the Toquimaphyllum beds of the Pyramid
Hill section.

The upper 120-m unit of the formation in the Pine
Hill block is terminated on the east by the Coal Can-
yon fault. It is possible that the total thickness of this
unit in unfaulted sections is much greater than 120 m.

STRATIGRAPHIC PALEONTOLOGY AND AGE OF
ROBERTS MOUNTAINS FORMATION AT PINE HILL

Fossils collected through the 450 m of Roberts Moun-
tains Formation in the Pine Hill block show the age to
range from Early Silurian (late Llandoverian) for the
lower beds to the Lower Devonian (Gedinnian) for the
upper 100 m or so of the formation. This range in age is
assigned on the basis of graptolites identified by
W. B. N. Berry (written commun., Nov. 8, 1968). The
upper 120-m unit contains abundant corals in the more
massive beds; Carlinastraea, which is especially abun-
dant, is considered representative of the Great Basin
Silurian coral zone E.

 

13

Coiled graptolites in beds a few feet above the basal
chert are reported as late Early Silurian (late Llan-
doverian). Graptolite assemblages near the top of the
lower 330-m unit include Monograptus praehercynicus
J aeger.

Some limonitic silty limestone and siltstone beds
about 140 m stratigraphically above the base of the
Roberts Mountains Formation contain a graptolite as-
semblage reported upon by W. B. N. Berry (written
commun., Oct. 16, 1972) as:

Lobograptus ”scanicus”

Monograptus bohemicus?

Monograptus colonus

Monograptus sp. (of the M. dubius type)
The age of this horizon is considered by Berry to be
early Ludlovian. Such a low position for early Ludlo-
vian, some 310 m below the top of this section, suggests
that the Wenlockian part of the formation is relatively
thin compared with the Ludlovian.

The upper 120-m lithologic unit of the Roberts
Mountains Formation at Pine Hill (the type Windmill
Limestone of Johnson, 1965) is primarily thick-bedded
dark-bluish-gray medium- to fairly coarse grained
bioclastic limestone with thin-bedded limestone and
calcareous shaly intercalations. The coarse-grained
beds are made up of clastic debris, and most are
graded. This unit forms prominent outcrops and the
change from the platy and laminated limestones of the
lower division is gradual. As described by Berry and
Mullens (written communs., 1968), the Monograptus
praehercynicus beds must lie near the base of this
upper unit. Corals and brachiopods, especially corals,
are abundant in the upper unit; the most abundant
coral is the large, massive Favosites. A zone about 20 m
thick above the middle of this unit has yielded the
following fossils:

Favosites sp. (massive)

Cladopora sp.

Alveolites sp.

Syringopora sp.

Striatopora? sp.

Rhegmaphyllum? sp.

Brachyelasma sp. c

Tryplasma sp., cf. T. duncanae (fragmentary)

Tonkinaria simpsoni Merriam

Stylopleura sp. c, cf. S. berthiaumi Merriam

Carlinastraea tuscaroraensis Merriam

Gypidula sp.

Isorthis sp. (ventral valve)

Small dalmanellid brachiopod (dorsal valve)
This assemblage containing Tryplasma, Tonkinaria,
and Stylopleura suggests that of Great Basin Silurian
coral zone D at the Roberts Mountains Formation type
section, although its most distinctive coral, Carlina-

14

straea, was not found at the type section. The species of
Carlinastraea found at Pine Hill occurs in the upper-
most fossil bed at Bootstrap Hill in the Tuscarora
Mountains and at locality M1446 on the pediment
slope north of Red Hill in the Simpson Park Moun-
tains where it is associated with Australophyllum (To-
quimaphyllum) johnsoni Merriam and Stylopleura.
Such an association, in particular with To-
quimaphyllum, suggests that there is no profound
stratigraphic separation between the Carlinastraea
beds at Pine Hill and those of Great Basin Silurian
coral zone E on the east side of Coal Canyon (Pyramid
Hill block), in which Australophyllum (Toquimaphyl-
lum)johnsoni is the most distinctive rugose coral. Lit-
tle is known of the stratigraphic range of any of these
seemingly distinctive Rugosa.

FOSSILS COLLECTED WITHIN THE
(TOAI. (IANYON FAULT ZONE

Several important fossil occurrences are within dis-
turbed rocks of the Coal Canyon fault zone, and be-
cause of this, their true stratigraphic position remains
uncertain. Among the fossils are the compact aseptate
pycnostylid Stylopleura? sp. c (pl. 2, figs. 1 and 2) from
locality M1379,Australophyllum sp. c (pl. 8, figs. 3—7),
from locality M1318 and Verticillopora annulata (pl.
10, figs. 1—3) from locality M1411. From their positions
in the fault zone, it appears probable that all these
fossils came from horizons stratigraphically higher
than the Carlinastraea beds.

PHYSICAL STRATIGRAI’HY ()1: THE
PYRAMID HILL SECTION

In Pyramid Hill, east of the Coal Canyon fault zone,
about 400 m of east-dipping limestone and thinly
bedded calcareous shaly and silty deposits include the
uppermost part of the Roberts Mountains Formation
(the Windmill Limestone of Johnson, 1965) and the
overlying Rabbit Hill Limestone. About 150 m of the
Roberts Mountains Formation is present here. The
Rabbit Hill underlying most of Pyramid Hill continues
eastward. As the depositional contact between the two
formations is gradational, placement is arbitrary as
understood at this time. The paleontologic change in
corals, however, is profound with complete disappear-
ance upward of all Rugosa of Silurian affinities and
Rugosa classified previously as Silurian types (Mer-
riam, 1973a). Only the small solitary variety Syringa-
xon is present in the Rabbit Hill Devonian of this sec-
tion.

Within the Roberts Mountains Formation along the
steep lower east slopes of Coal Canyon are bold mas-
sive outcrops of the more thickly bedded lenticular and
locally fossil-rich limestones. Much of this lower slope

 

ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

is covered by talus mantle that is the source of weath-
ered fossil material collected here. Some of the float
fossils, like many large Rugosa, however, are traceable
to their source beds.

The uppermost Roberts Mountains Formation of the
Pyramid Hill is made up of fine-textured dark— to
medium-dark-gray laminated platy to flaggy lime-
stone, and thick-bedded (2 cm—2 In) coarse slightly
bluish-gray bioclastic limestones, most of which are
graded. Some of the more massive beds are lenticular,
and locally they form prominent cliff exposures. The
bioclastic beds, which are composed in considerable
part of crinoidal debris, also contain abundant corals,
brachiopods, and other fossils. In some places all fossils
are silicified and weather out a limonite brown color.
The thicker bedded limestones above the middle of the
unit include numerous lenticular bodies of coarse-
textured depositional limestone breccia in which some
clasts are more than a foot in greatest diameter and
range in shape from subangular to rounded. In some of
the beds the corals present are surrounded by a
coarse-grained and fine—grained limestone matrix;
some beds are graded and of uniform thickness. Above
the interval of thicker bedded coral-rich limestone and
depositional breccia, the Roberts Mountains Forma-
tion becomes thinner bedded in about its uppermost 23
m, approaching the transition interval into overlying
Rabbit Hill Limestone. In general, the lower part of the
Rabbit Hill is much like the platy thin-bedded Roberts
Mountains beds, but coarser textured bioclastic beds of
the Rabbit Hill lack the bluish cast of such fossil-rich
limestone beds in the Roberts Mountains. Tentaculites
is common in the lower part of the Rabbit Hill Lime-
stone. The characteristic Leptocoelia of the Rabbit Hill
Limestone becomes abundant in Leptocoelia beds about
100 m stratigraphically above the base of the Rabbit
Hill as mapped. The dark-gray platy limestones and
calcareous shale and silty beds of the Rabbit Hill com-
monly weather very light gray.

In the upper part of the Roberts Mountains Forma-
tion of the Pyramid Hill section, the coral-rich more
massive beds with depositional limestone breccia are
referred to as the ”upper coral zone with Toquimaphyl-
lum.” On the west side of Coal Canyon in the Pine Hill
block, the coral-rich beds are distinguished as the
”lower coral zone with Carlinastraea.” The upper coral
zone with Toquimaphyllum is the primary reference
section for Great Basin Silurian coral zone E of Mer-
riam (1973a). These rocks are Lower Devonian in age
based on graptolites.

All Pyramid Hill fossils dealt with in this report
came from a stratigraphic interval of about 50 m in the
middle and upper parts of the Roberts Mountains For-
mation on the east side of Coal Canyon. This interval

TUSCARORA MOUNTAINS

includes the thicker bedded coral-rich limestone and
allogenic depositional limestone breccia. Some of the
fossil material came directly from the bold outcrops in
place, but much of it was collected on the talus below
the bold exposures. The common fossils of this 50 m
interval are:

Stromatoporoids

Favosites sp. (massive)

Cladopora sp.

Alveolites sp.

Stylopleura nevadensis Merriam

Stylopleura berthiaumi Merriam

Mucophyllum oliveri Merriam

Kodonophyllum mulleri Merriam

Rhizophyllum cf. R. enorme (Oliver)

Chonophyllum simpsoni Merriam

Kyphophyllum sp. c

Australophyllum (Toquimaphyllum) johnsoni

Merriam

Orthostrophia sp.

Schellwienella? sp.

Barrandella? sp.

Sicorhyncha? sp.

Rhynchospirina sp.

Plectatrypa? sp.

Atrypa sp.

Meristella sp.

Kozlowskiellina sp. f

Verticillopora cf. V. annulata Rezak

The rugose coral assemblages in the coral-rich lime-
stone interval of the Pyramid Hill exposures are of
Silurian character as compared with assemblages of
the Gotland, Sweden, Silurian standard and with those
of Silurian strata of the Klamath Mountains, Calif,
and Australia.

Mucophyllum oliveri, the most distinctive fossil in
this fauna, bears a fairly close resemblance to
M ucophyllum of the Silurian Gazelle Formation of the
Klamath Mountains, Calif., and to Silurian Mucophyl-
lum crateroides (Etheridge) of Australia. Similar cor-
als from Gotland, Sweden, have previously been re-
ferred to Schlotheimophyllum or erroneously t0
Chonophyllum. Kodonophyllum is represented in the
Gotland section, as is the slipper coral Rhizophyllum,
which does, however, pass upward into the Early De-
vonian of eastern Europe. Kyphophyllum is a Silurian
genus in Gotland but may range into earliest Devonian
in the Klamath Mountains. Toquimaphyllum, pro-
posed by Merriam (1973a) as a subgenus of the long-
ranging Australophyllum in Silurian and Devonian
rocks, is itself known in the Great Basin in later Silu-
rian beds. The little-known pycnostylid Rugosa, which
include Pycnostylus and Stylopleura, are characteristic
of the Silurian System.

 

15

A float specimen from Coal Canyon assigned to the
genus Salairophyllum, first reported from the Ural
Mountains of the U.S.S.R., was probably derived from
the higher Roberts Mountains limestone. In southeast-
ern Alaska, Salairophyllum occurs in the Late Silurian
limestones (Merriam, 1972) associated with Con-
chidium alaskensis, an index fossil of the Ludlovian
Stage in Alaska.

Verticillopora, the large dasycladacean alga, is
mostly confined to Silurian rocks of the Great Basin. In
the Vaughn Gulch Limestone of the Inyo Mountains, it
crosses the line into earliest Devonian at the base of
the uppermost Vaughn Gulch limestone unit.

PROBLEM OF THE SILL'RIAN«DI€\'ONIAN B()L'NI)ARY
A'l‘ PYRAMID HILL

A systematic study has been made (Merriam, 1973a)
of the rugose corals from thick-bedded Roberts Moun-
tains limestone of the upper coral zone with T0-
quimaphyllum, the reference section of Great Basin
Silurian coral zone E as defined by Merriam (1973a).
This coral zone contains distinctive genera and sub-
genera represented in the Silurian of Gotland, Sweden,
in the Klamath Mountains Silurian of northern
California (Merriam, 1972), and in the Silurian of Aus-
tralia. None of these genera range into the overlying
Rabbit Hill Limestone.

It is significant that no fossils have been collected
through a stratigraphic interval of about 100 m from
the top of the uppermost Roberts Mountains thick-
bedded coralline limestone to the lowest fossils of the
Rabbit Hill Limestone. The contact between the two
formations as mapped is arbitrary, and from the coral
evidence, with reference to Gotland, Sweden, the
Silurian-Devonian boundary is discretionary and as-
sumed to lie somewhere within the 100 m interval.

The rugose coral evidence bearing upon the
Silurian-Devonian boundary clearly does not agree
with that derived from study of the graptolites and
from conodont research. The base of the Monograptus
uniformis Zone, which is accepted as defining the base
of the Devonian, places the boundary about 250 m
lower in the section in the Pine Hill block on the west
side of Coal Canyon. To clearly resolve this type of
boundary problem will require the cooperative effort of
specialists dealing with all the fossil groups repre-
sented in these rocks, emphasizing graptolites, cono-
donts, brachiopods, and rugose corals.

ROBERTS MOUNTAINS FORMATION,
TUSCARORA MOUNTAINS

As a host rock of gold, the Roberts Mountains For-
mation has been traced widely in the Tuscarora Moun-

16

tains and nearby areas of Elko and northern Eureka
Counties, Nev. Structural complexity is everywhere
characteristic of the formation, where, as part of the
autochthonous group of rocks, it is overridden by grap-
tolitic shales, argillites, and cherts of the Vinini For-
mation (Roberts and others, 1958). Complete strati-
graphic sections of the Roberts Mountains Formation
are rare here, but the basal chert is exposed 4 miles
(6.4 km) southwest of the Big Six Mine (Berry and
Roen, 1963) and at the gorge on Maggie Creek 8 miles
(12.8 km) northwest of Carlin. Rocks of the unnamed
Devonian limestone unit of Mullens (Evans and Mul—
lens, 1976; T. E. Mullens, unpub. data, 1975) are above
the Roberts Mountains Formation at Bootstrap Mine
and at Maggie Creek. The section at the Carlin mine,
though much faulted, seems to be nearly complete.

An excellent partial section occurs at the Bootstrap
mine on Boulder Creek 22 miles (35.2 km) north-
northeast of Dunphy, a short distance north of the
Eureka-Elke County line. Although the basal chert is
not exposed here, about 470 m of strata with several
coral-bearing fossil zones has been measured by T. E.
Mullens (unpub. data, 1975) at this locality. Evans and
Mullens (1976) divide this section of rocks into two
units, the lower 180 In called Roberts Mountains For-
mation and the upper 275 m termed unnamed Devo-
nian limestone. We favor including the lower part of
the unnamed Devonian limestone unit in the Roberts
Mountains Formation because it is similar to the upper
part of that formation at many places in central Ne-
vada, in particular, the reference section at Coal Can-
yon in the Simpson Park Mountains. The upper part of
the unnamed Devonian limestone unit of Evans and
Mullens (1976) looks like the Rabbit Hill Limestone
and is probably correlative with that formation. An
alternative nomenclature, in line with other studies of
the Silurian and Lower Devonian in central Nevada,
would term the lower part of the unnamed unit of
Evans and Mullens (the top of our Roberts Mountains
Formation) the Windmill Limestone (Johnson, 1965)
and the upper part the Rabbit Hill Limestone. The
lumping of rocks into a general unnamed unit obscures
basic lithologic similarities and correlations and is a
step backward in our understanding of the paleotec-
tonics of the region. Collections of unusually well-
preserved silicified fossils made in this vicinity by R. J.
Roberts during reconnaissance mapping of northern
Eureka County convincingly demonstrated the Silu-
rian age of some of the limestones. Fossil collections
along the Mullens section traversed by Mullens and
Merriam make possible a significant correlation with
the Coal Canyon reference section and indirectly with
the Roberts Mountains Formation type section.

 

ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

PHYSICAL STRATIGRAPHY OF
THE BOOTSTRAP HILL SECTION

Measurement of the Roberts Mountains Formation
at Bootstrap Hill by T. E. Mullens (unpub. data, 1975)
shows two major lithologic divisions totaling about 470
m. This section does not include the base of the forma—
tion, which presumably is the black chert unit. The
lower division, 180 m of which is exposed, is made up of
platy splitting laminated limestone with thicker inter-
beds of bioclastic and pelletal limestone. Of these
strata, the fine-textured laminated limestones pre-
dominate. The upper 275 m unit consists of thicker
bedded coarser bioclastic and pelletal limestone with a
few intercalcalations of laminated limestone, espe-
cially the lower 50 m. Corals and brachiopods are
abundant in some beds of the upper unit. The bioclastic
and pelletal beds commonly exhibit graded bedding;
many of these beds include breccia fragments and
scour surfaces at the base.

The Bootstrap Hill section is possibly truncated at
the top by a thrust fault (T. E. Mullens, written com-
mun., 1972). The coral-bearing bed, that of Carlinas-
traea tuscaroraensis, lies about 400 m stratigraphically
above the bottom of the section.

STRATIGRAPHIC PALEONTOLOGY OF THE
BOOTSTRAP HILL SECTION

Three faunal zones are recognizable at Bootstrap
Hill on the basis of corals and brachiopods. These
range in ascending age from possible Great Basin Silu-
rian coral zone A to coral zone D or E. The uppermost
beds have yielded no coral fauna, but conodonts are
varieties found in the Rabbit Hill Limestone.

Lowest coral-brachiopod zone—Two fossil collec-
tions were made by R. J. Roberts, one from the south-
west base of Bootstrap Hill (M1 120) and the other from
the west base of the next hill to the south (M1412).
Both collections were taken from talus masking the
lowest exposed strata.

The collection from locality M1412 is diverse and
distinctive; it includes, among other fossils, the follow-
ing forms:

Cyathophylloides sp. f

Cladopora sp.

Alveolitid tabulate coral

Conchidium sp. b

Fardenia sp. b

Ptychopleurella sp.

Coelospira sp. b

Kozlowskiellina sp. b

Merista sp.
The fossils from locality M1120 at the southwest base
of Bootstrap Hill are Cyathophylloides sp. f,
Brachyelasma sp. b, Heliolites sp., and Favosites sp.

TUSCARORA MOUNTAINS 17

The fossils at both localities are silicified and as-
sociated with chertified sedimentary material that is
characteristic of lower beds of the formation near the
basal chert marker. The marker bed presumably is
lower in the section but is not exposed. The primitive
colonial rugose coral Cyathophylloides in each of these
assemblages resembles C. fergusoni of the Great Basin
Silurian coral zone A described in collections from the
Toquima Range.

Middle coral-brachiopod zone—A 60-m strati-
graphic interval starting 180 m from the base of the
section and at the bottom of the more massive bioclas-
tic sequence contains fossil assemblages that include
the following forms:

Cladopora sp.
Coenites sp.
Favosites (massive)
Stylopleura sp. b
Calostylis? sp.
Kodonophyllum sp. b
Kyphophyllum sp. b
Resserella sp.
Leptaena sp.
Salopina? sp.
Gypidula sp.
Coelospira sp.
Trematospira? sp.
Atrypa sp.
Howellella sp.
Glassia 0r Cryptatrypa sp.

Upper fossil zone with Carlinastraea.—Collecti0ns
from what is here called the Carlinastraea bed, 70 m
stratigraphically below the top of the Bootstrap Hill
section, were made by R. J. Roberts in 1958 and were
supplemented by additional collections by Mullens and
Merriam in 1969. The complex rugose coral Carlina-
straea occurs in very large colonies 1 m or more in
diameter, as it does at Coal Canyon in the Simpson
Park Mountains. Fossils found in the Carlinastraea
bed at Bootstrap Hill are:

Cladopora sp.

Alveolites sp.

Favosites (massive)

Rhegmaphyllum sp.

Syringaxon? sp.

Tryplasma sp. cf. T. duncanae Merriam
Kyphophyllum? sp., cf. K. sp. b
Carlinastraea tuscaroraensis n. gen., n. sp.
Salopina? sp. (dorsal valve)

Large dalmanellid brachiopod (ventral valve)
Abundant crinoidal debris

 

AGE OF THE ROBERTS MOUNTAINS FORMATION
AT BOOTSTRAP HILL

Coral and brachiopod evidence points to a Silurian
age for part of the Bootstrap Hill section with an age
range from Early Silurian (Great Basin Silurian coral
zone A) for the lower beds containing Cyathophylloides
to Late Silurian (Great Basin Silurian coral zone D or
E) for the higher beds containing Carlinastraea. Like
the the type and reference sections of the Roberts
Mountains Formation, the upper part is Lower Devo-
nian. This age, as elsewhere, is based on the graptolite
standard which in central Nevada places the
Silurian-Devonian boundary at a lower stratigraphic
position than the corals would suggest.

Except for Coelospira sp. b, the brachiopod as-
semblage from the lowest faunal zone shows little simi-
larity to known assemblages from other areas; the
brachiopods of Great Basin Silurian coral zone A are in
general poorly known.

The faunas of the middle coral-brachiopod zone gen-
erally fall in line with a Silurian age, in particular the
Rugosa Stylopleura, Calostylis?, Kodonophyllum, and
Kyphophyllum. Several of the brachiopods range up-
ward into the Devonian; those provisionally assigned
to Salopina?, Coelospira, and Glassia or Cryptatrypa
are possibly more in harmony with a Silurian age.

The remarkable colonial rugose coral Carlinastraea,
though resembling Devonian forms conventionally as-
signed to Spongophyllum, is generically quite distinct.
Carlinastraea tuscaroraensis, which is specifically
identical to that from Bootstrap Hill, occurs in the
Simpson Park Mountains at Coal Canyon in beds with
a coral fauna quite similar to that of Silurian coral
zone D in the Roberts Mountains type section. Car-
linastraea of a similar kind occurs in association with
Australophyllum (Toquimaphyllum) johnsoni and
Stylopleura cf. S. nevadensis in beds assigned to Great
Basin Silurian coral zone E at locality M1446 in the
northern foothills of the Simpson Park Mountains.
Carlinastraea at Bootstrap Hill is therefore suggestive
of either Great Basin Silurian coral zone D or E.

Studies of graptolites from the lower 180 m of the
Mullens section (unpub. data, T. E. Mullens, 1975) (by
W. B. N. Berry) give evidence for a higher position in
the Silurian System than do the corals. Monograptus
in beds from about 45 m above the base to about 90 m
include:

Monograptus sp. (plain thecae)

Monograptus sp. (appears to have thecae with
spines similar to those in M. chimaera)

Monograptus sp. (of the M. dubius type?)

Monograptus sp. (thecae appear to be similar to
those of M. uncinatus)

18

Berry’s conclusion (written commun., Nov. 8, 1968) is
that these graptolites are possibly of Ludlovian Late
Silurian age. Other graptolites from horizons about
175 In and 185 m above the base of the section are:
Monograptus angustidens Pribyl
Monograptus uniformis Pribyl
Their age is given as Earliest Devonian (Monograptus
uniformis Zone).

ROBERTS MOUNTAINS FORMATION OF
THE NORTHERN MONITOR RANGE

At Copenhagen Canyon near Rabbit Hill in the
northern Monitor Range, the Roberts Mountains For-
mation is represented by thin-bedded laminated
graptolite-bearing silty limestone and thin- to
medium-bedded clastic limestones. It is overlain by
Rabbit Hill Limestone. These Silurian and Lower De-
vonian strata were studied by Merriam and Anderson
(1942, p. 1687) and later described in more detail after
reconnaissance geologic mapping and stratigraphic
measurement by Merriam (1963). A recent study by
Matti, Murphy, and Finney (1975) focuses on the stra-
tigraphy and environment of deposition of the Silurian
and Lower Devonian rocks of this area and revises the
reconnaissance map.

The most complete and measurable sequence of
Roberts Mountains Formation in Copenhagen Canyon
underlies an unnamed hill whose summit is about 1.6
km north-northeast of the top of Rabbit Hill in the
SW14 sec. 36, T. 16 N., R. 49 E. The formation to the top
of the unnamed hill measured about 180 m (Merriam,
1963, p. 38); beds of several hundred metres more are
present west of the hill but poorly exposed. A thickness
of 480 m was measured by Matti, Murphy, and Finney
(1975) on this traverse. The section is made up of platy
to shaly weathering argillaceous limestone and cal-
careous shale grading upward into thin- to medium-
bedded clastic limestones with fine-grained laminated
limestone interbeds. On fresh surfaces these argilla-
ceous beds are dark gray and fine textured; on weath-
ering they become light gray or buff colored. Bioclastic
and graded beds occur as sporadic interbeds in the
middle part of the section and as the main lithologic
type in the upper part; they are about 12 cm thick and
are composed largely of fine sandy material with
crinoidal debris. The platy silty limestones contain an
abundance of graptolites best seen on weathered sur-
faces. No thick coarse bioclastic limestone lenses con-
taining a diverse colonial coral fauna were found in
this section, but brachiopods, which were collected
from high in the section, are reported by Johnson,
Boucot, and Murphy (1967).

The lower 30—40 m of the Roberts Mountains Forma-
tion at the unnamed hill is a very cherty limestone

 

ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

that is assumed to be correlative with, or to include,
the basal Roberts Mountains chert marker of other
Great Basin sections. It is, however, classified as the
top of the underlying Hanson Creek Formation by
Matti, Murphy, and Finney (1975). This conspicuously
banded member consists of interbedded dark-gray or
slightly bluish-gray fine-grained limestone and dark-
gray chert that weathers limonite brown. Uneven
lenses and pinch-and-swell beds of chert, 2—12 cm
thick, make up one-third to one-half of this cherty unit.

Above the cherty member, for at least 140 m to the
top of the hill, are thin—bedded fine-grained argilla-
ceous limestones that are dark gray on fresh breaks
but weather light gray with buff- and brownish-colored
patches. A few dark-gray chert nodules occur at places
in this interval.

PHYSICAL STRATIGRAPHY

The contact at the bottom of the lowest chert bed
reveals no convincing physical evidence of erosion and
disconformity with the underlying Hanson Creek
Formation, of Late Ordovician and Early Silurian age.
Of possible significance regarding the system bound-
ary is a persistent calcareous sandstone bed that lies
about 12 m stratigraphically below the chert. This fine
sandstone contains abundant chert granules. Accord-
ing to F. G. Poole (oral commun., 1968), a sand of this
kind occurs Widely in the central Great Basin in about
the same stratigraphic position. This bed provides a
useful datum with reference to base of the Silurian
System; it is especially valuable in sections lacking the
chert marker.

The apparent thinning of the Roberts Mountains
Formation at Copenhagen Canyon from the relative
thick sections to the north is part of the gradual thin-
ning of the unit to the west and south. In the Toquima
Range to the west, two thrust plates containing rocks
that were originally deposited farther west (presuma-
bly in the vicinity of the Toiyabe Range) contain com-
plete sections of Roberts Mountains Formation that
are 106 m thick and less than 3 m thick, respectively.
Similarly, in the northern Inyo Mountains, Calif., a
northward change of the Vaughn Gulch Limestone to
graptolite-bearing shaly deposits was accompanied by
a thinning of strata representing the Vaughn Gulch
interval (Ross, 1966, p. 32).

STRATIGRAPHIC PALEONTOLOGY AND AGE
OF THE ROBERTS MOUNTAINS FORMATION
AT COPENHAGEN CANYON

Studies of graptolites and conodonts provide most of
the paleontologic evidence of age of this formation in
the Monitor Range; they indicate the age of the forma-

DOBBIN SUMMIT, MONITOR RANGE

tion as Silurian and Lower Devonian. Generically un-
determined pentameroid brachiopods about 3 cm long
observed in the field near the top of the cherty unit
suggest that this unit is best assigned to the Silurian
System, in agreement with the graptolites and cono-
donts. The sporadic crinoidal limestone beds may even-
tually yield other shell megafossils of diagnostic age
significance.

Graptolites identified by Ruedemann (Merriam and
Anderson, 1942, p. 1687) came from surface rubble a
few feet above the chert. These were identified as
Monograptus acus Lapworth and M onograptus pandus
Lapworth, suggesting to Ruedemann the approximate
age of the lower and middle Gala beds of England, or of
the Clinton Group (Middle Silurian) and younger Silu-
rian beds in New York State.

Several graptolite collections made by Mullens and
Merriam from higher in the section and identified by
Berry include the following forms:

(float near top of basal chert, 33 m above base of forma-
tion)
Cyrtograptus sp.
Monograptus priodon (Bronn)
Age: In the span of late Llandovery to early Wen-
lock.

(float 33—84 m above base of formation)
Cyrtograptus sp.
Monograptus flemingii (Salter)
Age: Probably Wenlock.

(100 m above base of formation)
Monograptus dubius (Suess)
Monograptus uncinatus Tullberg
Gothograptus spinosus Wood
Age: Early Ludlow; Monograptus nilssoni—M.
scanicus Zone.

(approximately 106 m above base of formation)
Monograptus sp. cf. M. nudus type?
Monograptus sp. cf. M. jaculum type?

Age: In the span of middle Llandovery to Ludlow.

(90—150 m above base of formation)
Monograptus flemingii (Salter)?
Monograptus sp. (of the M. dubius type)

Age: Probably late Wenlock.

Graptolites reported by Matti, Murphy and Finney
(1975) include Monograptus spiralis and Retiolites
geinitzianus angustidens 1 m above the top of the chert
(33 m above the base of the formation as used here)
these forms are late Llandoverian. Collections from
high in the formation (in the Windmill Limestone as
mapped by Matti and others, 1975) include Monograp-
tus birchensis, M. praehercynicus, and M. hercynicus;
those species indicate an Early Devonian age.

 

19

ROBERTS MOUNTAINS FORMATION AT
BROCK CANYON, MONITOR RANGE

At Brock Canyon on the west side of the range, the
Roberts Mountains Formation is exposed as parts of
two separate thrust plates. One plate contains all the
Middle and Upper Ordovician formations (Antelope
Valley Limestone, Copenhagen Formation, Eureka
Quartzite, and Hanson Creek Formation) recognized to
the east around Antelope Valley as well as the Roberts
Mountains Formation; the second plate contains
Roberts Mountains Formation directly on the Antelope
Valley Limestone. The Roberts Mountains Formation
in both plates is finely laminated thin-bedded graptoli-
tic silty limestone, but the basal chert is present in
only one of the two sequences—the plate containing
the complete series of Ordovician formations. The for-
mation is at least 180 m thick, but the total thickness
of the formation in either plate is unknown as it is the
youngest unit in the respective sequences.

ROBERTS MOUNTAINS FORMATION AT
DOBBIN SUMMIT, MONITOR RANGE

In the middle part of the Monitor Range at Dobbin
Summit and Clear Creek, the Roberts Mountains For—
mation has been mapped by F. J. Kleinhampl
(Kleinhampl and Ziony, 1967). In that area the forma-
tion is underlain by the Hanson Creek Formation and
overlain by Rabbit Hill Limestone. This occurrence of
the Roberts Mountains is of special significance as it is
partly dolomitic, suggesting proximity to the border
zone between the eastern dolomite belt and the inter-
mediate limestone belt as at Roberts Creek Mountain
and at Bare Mountain near Beatty, Nev. Rocks from
the August Canyon thrust sequence in the Toquima
Range that are in part correlative with the Roberts
Mountains Formation are also dolomitic. The basal

chert member was not found. Kleinhampl states:

The Roberts Mountains Formation consists of two main units. The
lower contains alternating pale brown-weathering slope-forming
platy limestone and thinner but conspicuous medium-dark-gray
ledgy limestone and dolomite containing abundant macerated fossils
(crinoid columnals and corals). This unit closely resembles the Mas-
ket Shale ofKay and Crawford (1964, p. 439) in the Ikes Canyon area
of the Toquima Range. An overlying gray massive cliffy dolomite
and limestone unit is commonly present in the Monitor Range and is
tentatively considered to be the upper part ofthe Roberts Mountains.
It could be correlative with part of the Lone Mountain Dolomite.
Because of the questionable age and name assignment and thinness
of units, the Late Ordovician through Silurian strata are shown as
undifferentiated dolomite on the northern Nye County geologic map.
In the Dobbin Summit area, the Roberts Mountains is no more than
about 60—120 m thick and consists mainly of the lower unit. In con-
trast, near Clear Creek, the lower member is 90 m thick and the
upper gray massive dolomite member is 100 m thick (Greene, 1953,
p. 27). Here the top is faulted out according to Greene.

The Rabbit Hill Limestone overlies the Roberts Mountains Forma-
tion in the Dobbin Summit area. The Rabbit Hill consists of very

20

fossiliferous somewhat platy slope-forming limestone that is poorly
exposed and weathers to chips and plates of pale yellowish- and pale
reddish-gray and yellowish—brown colors. The formation may form
an incomplete section as little as less than 100 to about 245 m thick
and truncated at its top by a low-angle fault. The fault zone is
marked by a discontinuous very dark gray chert.

ROBERTS MOUNTAINS FORMATION
AT BARE MOUNTAIN

Of special interest are those localities where the
Great Basin Silurian gives evidence of a position near
a lateral transition from dolomite of the eastern dolo-
mite belt to limestone of the intermediate limestone
belt, such as Bare Mountain near Beatty, Nev., and the
Roberts Mountains type section of central Nevada.

At Chuckwalla Canyon, near Bare Mountain,
Cornwall and Kleinhampl (1960) mapped 300 m of
Silurian rock as two formations. The upper unit, being
entirely dolomite about 114 m thick, was assigned to
the Lone Mountain Dolomite; the lower unit, about
190 m thick, was referred to the Roberts Mountains
Formation; this lower unit is made up of alternating
members of dark-gray limestone, dolomitic limestone,
and dolomite; one-third to one-half of this sequence is
dolomite. A Silurian age assignment is reasonable, for
at Bare Mountain these beds occupy a stratigraphic
interval between the Late Ordovician Ely Springs
Dolomite and superjacent dolomite assigned to the De-
vonian.

The Bare Mountain sequence can be compared with
the Lone Mountain Dolomite at its type section. As
presently interpreted by Merriam (1973b), the type
Lone Mountain includes a lower dark-gray dolomite
called Lone Mountain Dolomite unit 1 and an upper
light-gray dolomite termed Lone Mountain unit 2.
Lone Mountain unit 1 is lithologically comparable in
many respects to the Roberts Mountains Formation of
Cornwall and Kleinhampl at Bare Mountain but dif-
fers by containing no limestone.

N0 fossils of stratigraphic significance were iden-
tified by Merriam (1973b) during the course of his work
in the Lone Mountain Dolomite of the type section. The
middle part of Lone Mountain unit 1 contains partly
silicified brachiopods and corals, locally in abundance.
None of the fossils prepared by acid etching were ge-
nerically determinable; they include small pentamer-
oids, small rhynchonellid brachiopods, and tabulate
corals. Lone Mountain unit 2, the upper light-gray
unit, has yielded a poorly preserved cerioid rugose
coral and in dark—gray lenses of this upper division,
colonial forms probably of the genus Entelophyllum.
There are unconfirmed reports that larger pentamerids
were collected from an unknown part of the Lone
Mountain in its type section. In the Mahogany Hills

 

ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

and Fish Creek Range, Eureka County, Nev., identifi-
able fossils are present in Lone Mountain unit 2 (Mer-
riam, 1973b). At Bare Mountain, the upper formation,
or Lone Mountain Dolomite of Cornwall and Klein-
hampl, has yielded no fossils. The underlying dark unit
(Roberts Mountains Formation) contains abundant
silicified fossils in its middle part, in both the lime-
stone and the dolomite interbeds.

Correlation of the Bare Mountain strata with those
of central Nevada is based somewhat more on general
lithologic resemblance and stratigraphic sequence
than on fossil evidence. The silicified fossil as-
semblages from the middle part of the lower dark-gray
unit (Roberts Mountains Formation of Cornwall and
Kleinhampl), which come mainly from dolomite inter-
beds, are not closely related to known faunas of the
type Roberts Mountains Formation. Most abundant
are pentameroid brachiopods which include a large,
smooth Pentamerus-like genus, Conchidium of
medium to large size, and Virgiana? sp. A similar
Pentamerus-like genus occurs in the lower part of the
Roberts Mountains Formation at Coal Canyon, Simp-
son Park Mountains, Nev. In the type section, Roberts
Mountains pentameroids, especially Conchidium, are
present in great abundance near the top of unit 2, that
is, near the middle of the formation. The corals at Bare
Mountain are Heliolites sp., large Streptelasma—like
solitary forms, large solitary Rhabdocyclus sp. B, and
Stylopleura sp. resembling S. berthiaumi 0f the Great
Basin Silurian coral zone D. Near the base of the Bare
Mountain section, the colonial Palaeophyllum sp. b oc-
curs (Merriam, 1973a).

It is significant that a very cherty dolomite member
lies at the base of the Roberts Mountains Formation at
Bare Mountain. This member occupies the position of
the basal chert marker of many Great Basin sections of
the Roberts Mountains Formation.

ROBERTS MOUNTAINS FORMATION OF
THE NORTHERN TOQUIMA RANGE

Good exposures of the Roberts Mountains Formation
are found north of Petes Canyon, in the area between
Ikes and Mill Canyons, and in the area around East
and West Northumberland Canyons in the northern
part of the Toquima Range. The formation in these
localities occurs in different tectonic plates that have
presumably been thrust from sites of deposition west of
the Toquimas. A simplified geologic map, figure 3,
outlines these structural relations. A total of five
sequences of lower and middle Paleozoic rocks are
present in the thrust slices; when unraveled palinspas-
tically, they represent rocks from a large region in
central Nevada.

THE NORTHERN TOQUIMA RANGE 21

    
  

 

 

 

 

 

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EXPLANATION

Lower plate of Roberts Mountains thrust

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Eastern and some transitional facies of lower
and middle Paleozoic rocks

Upper plate of Roberts Mountains thrust

     
 

         

Western and transitional facies of lower

er Paleozoic rocks
and middle Paleozoic rocks

Cenozoic, Mesozoi ,

 

_.7_ ‘_A—-—' """""""
Fault Thrust fault
Sawteeth on upper plate, dotted where concealed

Contact

Bar and ball on down thrown side

FIGURE 3.—The northern Toquima Range showing Paleozoic sequences that contain Silurian rock in separate thrust sheets. Based on
geologic mapping by E. H. McKee in 1968—70.

22
PETES CANYON WINDOW

The Roberts Mountains Formation in the vicinity of
Petes Canyon (fig. 1, loc. 7; fig. 3) is exposed in the
Petes Canyon window in the Roberts Mountains thrust
(McKee and Ross, 1969). An incomplete section of the
formation is present here as the uppermost unit in the
autochthon. A number of partial sections including the
basal black chert unit are found; the thickest of these,
in the central part of sec. 10, T. 16 N., R. 46 E., south-
east corner of Lander County, contains more than 100
m of strata. The thickness of the order of 300 m esti-
mated by McKee and Ross (1969) should probably be
revised to about 200—250 m. p

The basal contact with rocks mapped as the Hanson
Creek Formation seems conformable, though obscured
by small faults or alluvium in most places. No angular
discordance was found between the Roberts Mountains
and Hanson Creek, but fossil evidence suggests a
hiatus between these formations.

The Roberts Mountains above the basal black chert
is mostly thin-bedded platy-splitting graptolite-
bearing argillaceous limestone. A few medium-bedded
limestones contain a rich coral fauna, but the strati-
graphic relation of these beds is not known because of
structural complications. Graptolites, which provide
the evidence for the age of lower parts of the formation,
include monograptids ranging from upper Lower Silu-
rian (Llandovery) into the upper part of the Middle
Silurian (Wenlock and possibly lower Ludlow). The
coral-bearing limestone beds contain forms typical of
the Rabbit Hill Limestone of Early Devonian age.

IKES CANYON WINDOW
«IUNE CANYON SEQL‘ENCE

In the area between Ikes and Mill Canyons, carbo—
nate strata of lower and middle Paleozoic age are ex-
posed in a window in the Roberts Mountains thrust
called the Ikes Canyon window (fig. 1, loo. 8; fig. 3). The
Roberts Mountains Formation (or its correlatives) oc-
curs in three somewhat different sequences of rocks
that have been thrust together and are now exposed in
this window. The upper thrust plate, named the June
Canyon sequence by Kay and Crawford (1964), con-
tains a metre or so of thin-bedded, platy-splitting grap-
tolitic limestone between massive beds of Ordovician
limestone and the Tor Limestone of Late Silurian and
Early Devonian age. The upper contact with the Tor is
conformable; the lower contact with Ordovician lime—
stone appears conformable but may be a fault. In all
places but one (approximately 1,500 m west of Ikes
cabin site), the massive limestone units (Ordovician
limestone and Tor) are in fault contact, the relatively
incompetent Roberts Mountains limestone having
been sheared out between them.

 

ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

The total thickness of Roberts Mountains Forma-
tion, here made up entirely of the thin-bedded graptoli-
tic limestone, is about 3 m. Fragments of the graptolite
Monograptus aff. M. praehercynicus indicate that the
few feet of strata that make up the formation in this
thrust plate correlate with the upper part of the forma-
tion elsewhere in central Nevada and are of Lower De-
vonian age. Corals from the bottom part of the Tor
above the graptolite horizon are typical of the Great
Basin Silurian coral zone E (McKee and others, 1972),
which is included in the Lower Devonian because of
the underlying Monograptus praehercynicus.

M I LL CANYON SEQL'EN C E

The middle thrust plate, named the Mill Canyon se-
quence by Kay and Crawford (1964) (fig. 1, loc. 9; fig. 3),
contains a complete section of the Roberts Mountains
Formation with both graptolites and corals. These
strata are well exposed on the ridges above the lower
reaches of Ikes Canyon.

The formation here is about 110 m thick and consists
mostly of thin-bedded platy argillaceous limestone
with increasing amounts of medium (5—30 cm) graded
beds of clastic limestone toward the top. There is no
chert at its base, and it rests with no obvious discon-
formity on massive limestone that contains Upper Or-
dovician fossils. The lowest fossils (graptolites) in the
Roberts Mountains of the Mill Canyon sequence occur
within a foot of its base and are Middle Silurian forms
(McKee, 1975). The fossil evidence indicates a hiatus
representing a time period of considerable duration at
the base of the formation. The upper contact with the
McMonnigal Limestone, gradational across an interval
of about 25 In, was arbitrarily drawn where medium-
bedded gray clastic limestone typical of the McMonni-
gal becomes the dominant lithology.

Graptolites that occur throughout the formation in-
clude late Middle Silurian (late Wenlock) forms at the
base, Upper Silurian Ludlow) types somewhat higher,
and Monograptus praehercynicus, which is Lower De-
vonian, in the upper part of the formation and in the
bottom of the McMonnigal Limestone.

The Roberts Mountains—McMonnigal sequence has
yielded coral faunas in normal order representing
three, A, D, and E, of the five Great Basin Silurian
coral zones. Coral zone A is represented by
Arachnophyllum kayi with which Cyathophylloides
fergusoni and Neomphyma crawfordi are associated.
Above this horizon, coral zone D contains Stylopleura
nevadensis, Tonkinaria sp., and large Verticillopora
annulata. Coral zones A and D are in the Roberts
Mountains Formation; coral zone E lies in the Mc-
Monnigal Limestone and includes Australophyllum

THE TOIYABE RANGE

(Toquimaphyllum) johnsoni and a species of Kypho-
phyllum.

AUGUST CANYON SEQUENCE

Rocks in the lowest thrust plate in the Ikes Canyon
window (fig. 1, 10c. 10, fig. 3) were named the August
Canyon sequence by Kay and Crawford (1964). It was
assumed by these geologists that this sequence of
strata is in situ, but it is possible that these rocks, along
with the overlying two plates (Mill Canyon and June
Canyon sequences), have moved from another region.
As its base has not been found, there is no structural
evidence bearing on the problem; stratigraphic consid-
erations such as regional facies patterns shed little
light on the site of deposition of the rocks. These strata
contrast so markedly with the strata of equivalent age
in the overlying thrust plates that new formational
names proposed by Kay (1960) and Kay and Crawford
(1964) seem appropriate. Rocks correlative with the
Roberts Mountains Formation include all or most of
the Gatecliff Formation of Kay (1960), the Bastille
Limestone Member of the Masket Shale of Kay and
Crawford (1964), and probably the lower part of the
upper member of the Masket Shale of Kay and Craw-
ford (1964). The name Masket Shale was used by these
workers (1964) for strata in the Mill Canyon and June
Canyon sequences; in this report and in others (McKee
and others 1972; McKee, 1976), those strata are called
the Roberts Mountains Formation.

The Gatecliff Formation of Kay and Crawford is
comprised of three distinctive units, all dolomitic. It
overlies with no apparent discordance dark-colored
limestone containing a distinctive fauna considered to
be Upper Ordovician (McKee, 1976). This Upper Or-
dovician limestone was named the Caesar Canyon
Limestone by Kay and Crawford (1964). Corals indica-
tive of the Silurian have been collected from the basal
unit of the Gatecliff (McKee, 1976), which is a light—
gray lithographic dolomite. The middle unit of the
Gatecliff is dolomite distinctive by the presence of
rounded quartz sand grains; no fossils have been found
in this rock. The upper unit of the Gatecliff is dolomite
and chert similar to the basal chert unit of the Roberts
Mountains Formation in most of central Nevada. No
fossils have been collected from this chert in the Au-
gust Canyon sequence, but a few miles south, s similar
chert unit in What is called the Prospect sequence by
Kay and Crawford (1964) has yielded graptolites that
indicate an Early Silurian age. The Bastille Limestone
Member of the Masket Shale of Kay and Crawford is
mostly unfossiliferous gray dolomite with medium—
bedded bioclastic limestones at the top. These lime-
stones contain a rich coral fauna equated with the
Great Basin Silurian coral zone E. Part or possibly

 

23

most of Silurian time is represented by the underlying
dolomite or at the basal contact with the underlying
Caesar Canyon Limestone of Kay and Crawford. The
upper part of the Masket Shale of Kay and Crawford is
thin-bedded laminated silty limestone, part of which
may correlate with the upper part of the Roberts
Mountains Formation and with the Rabbit Hill Lime-
stone. It is of Lower Devonian age on the basis of a
variety of Lower Devonian conodont forms (McKee,
1976).

NORTHUMBERLAND WINDOW

About 8 km south of the Ikes Canyon window, east-
ern to transitional facies (mostly carbonate) rocks are
exposed in the Northumberland window in the Roberts
Mountains thrust (fig. 1, 10c. 11; fig. 3). The rocks in
this window constitute the Prospect and Striped Hill
sequences of Kay and Crawford (1964), presumed to
have been thrust from the southwest to their present
location in the north—central part of the Toquima
Range (Kay and Crawford, 1964, fig. 8).

Both the Prospect and Striped Hill sequences con-
tain Roberts Mountains Formation (called Masket
Shale and Gatecliff Formation by Kay and Crawford,
1964) as their uppermost unit. The formation is typi-
cally thin-bedded platy-splitting argillaceous tan-
weathering limestone similar to rocks mapped as
Roberts Mountains Formation in most other places in
central Nevada. Black cherty limestone occurs at the
base of the formation. Monograptids from the chert
zone at Water Canyon north of East Northumberland
Canyon are indicative of the Lower Silurian (lower
Llandovery). An Early and Middle Silurian age is as-
signed to the overlying platy unit of the Striped Hill
sequence by Kay and Crawford (1964, fig. 5).

ROBERTS MOUNTAINS FORMATION
IN THE TOIYABE RANGE

The Roberts Mountains Formation crops out in
widely separated localities along most of the extent of
the Toiyabe Range. Many of these occurrences mark
the westernmost exposures of the formation at a given
latitude; these outcrops lie approximately along long
117°15’. It is assumed that these outcrops have not
been tectonically transported (thrust) from the west as
have many thrust plates in the Toquima Range.
Localities where partial or complete sections of Roberts
Mountains Formation are exposed include: Callaghan
window (fig. 1, loc. 18), about 24 km northeast of Aus-
tin; Dry Creek area (fig. 1, loc. 6), 11 km south-south-
west of Austin; Point of Rocks and Straight Canyon
area (fig. 1, 10c. 16), about 27 km southwest of
Austin; and Pablo Canyon (fig. 1, 10c. 12), about 16 km
west of Round Mountain. The formation crops out at a

24

few other localities in the Toiyabe Range where it has
not been studied in detail.

CALLAGHAN WINDOW

Lower Paleozoic carbonate strata are exposed in the
Callaghan window (fig. 1, loc. 18) in the Roberts Moun—
tains thrust about 24 km north of Austin (Stewart and
Palmer, 1967; Stewart and McKee, 1968). The Roberts
Mountains Formation is the top unit in the autoch-
thonous sequence and occurs in scattered outcrops in
the southern and northwestern parts of the window.
Since it is the top unit, its thickness is not known.
About 60 m can be measured in partial sections, but
the formation is probably three to four times thicker in
this part of the Toiyabe Range. The more than 1,000 m
reported by T. E. Mullens (unpub. data, 1975) seems
excessive on the basis of other measured sections in the
region. The Roberts Mountains Formation lies on dif-
ferent rock units at localities only a few miles apart. In
the Boone Creek area in the northern part of the win-
dow, it lies on Antelope Valley Limestone. There is no
obvious angular discordance between these forma-
tions, but a hiatus spanning the Upper Ordovician and
possibly part of the Lower Silurian must be repre-
sented at the contact. In the southern part of the win-
dow, it rests on rocks originally considered to be equiv-
alent to the Hanson Creek Formation (Stewart and
Palmer, 1967) but now considered likelier to be cor-
relative with the Copenhagen Formation (Stewart and
McKee, 1975). About 40 m of strata lithologically dif-
ferent from the underlying Antelope Valley Limestone
and overlying Roberts Mountains separates these for-
mations. At all places in the Callaghan window, the
Roberts Mountains consists of a basal black chert
about 10 m thick overlain by light-gray platy-splitting
silty limestone that contains monograptids. No coral-
line limestone has been found in the incomplete sec-
tions of the formation in this area.

DRY CREEK AREA

On the west side of the Toiyabe Range about 11 km
southwest of Austin, in the Dry Creek area, the
Roberts Mountains Formation (fig. 1, loo. 6) is the up-
permost unit of a section that includes Ordovician,
Cambrian, and Precambrian strata below. About
120 m of tan- or gray-weathering platy argillaceous
limestone makes up the formation in this area. There
is no basal chert unit, and the formation lies with ap-
parent conformity on medium-bedded Antelope Valley
Limestone. A few fragments of Monograptus have been
found in these platy rocks, and a collection of poorly
preserved corals comes from a thicker bed of limestone
near the top of the section. The corals, which include

 

ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

Favosites and Zelophyllum sp., suggest a Silurian age,
probably in the upper part of the system. In overall
aspect, this section resembles the Mill Canyon se-
quence of the Toquima Range, a sequence of strata in a
thrust plate assumed to have originated in the general
area of the Dry Creek section.

POINT OF ROCKS AND STRAIGHT CANYON

A faulted sequence of lower Paleozoic strata is ex-
posed in the western and central part of the Toiyabe
range in an area that includes Straight Canyon and an
area of about 10 km2 south of Reeds Canyon, includ-
ing Point of Rocks Canyon about 27 km south of Austin
(fig. 1, loc. 16). Here the rocks dip generally to the
north, forming a homoclinal sequence. This seemingly
simple structure is complicated by at least one thrust
parallel to the strike of bedding and other faults that
cut out, or repeat, parts of the section. Stratigraphic
thicknesses are estimates based on a number of trav-
erses across the section. The best exposure of the lower
part of the Roberts Mountains Formation and under—
lying units is in Straight Canyon (sec. 18, T. 16 N., R.
43 E.) about 1.6 km west of the Kingston ranger sta-
tion. Here about 3 m of dark chert and limestone that
make up the basal part of the Roberts Mountains lies
on a composite unit about 15 m thick of cherty lime-
stone and dark shale containing cryptolithoid trilo-
bites. These rocks are probably best correlated with
units in the Toquima Range named Hanson Creek
Formation (in Petes Canyon window) or Caesar Can-
yon Limestone in the August Canyon sequence of the
Ikes Canyon window. There is no angular discordance
between the unit and the Roberts Mountains chert, but
they are probably separated by a hiatus as elsewhere
in central Nevada. Above the chert is about 100 m or
more of gray-weathering platy argillaceous limestone
typical of the graptolite facies. A few monograptids
were found a short distance above the basal chert in
Straight Canyon and higher in the section on the west
side of Point of Rocks Canyon. The section from Point
of Rocks Canyon to the north side of the adjacent un-
named canyon to the north (unsurveyed sec. 36, T.
17 N., R. 42 E.) reveals about 300 m of thin-bedded
Roberts Mountains Formation. This thickness, how—
ever, is subject to speculation and is probably exces-
sive, for at least half the section is poorly exposed on
the dip slope, and numerous faults mapped at other
places in the region are probably present here. Scat-
tered graptolites collected in these rocks indicate that
they are forms considered to range from late Early
Silurian (late Llandovery) to Devonian in age (Stewart
and McKee, 1976). Further evidence for unresolved
structural complications is that the succession of grap-
tolite zones does not correspond to a simple traverse

LIMESTONES OF THE NORTHERN INYO MOUNTAINS

across the section. It is suggested here that the actual
thickness of the formation in this part of the Toiyabe
Range is of the order of 150 m. Thin- to medium-bedded
bioclastic limestones become more numerous toward
the top of the formation. Graptolites in this transition
zone are of the Monograptus hercynicus group. Higher
in the section, a massive limestone (about 4 m thick)
contains the corals Billingsastraea? sp. T, a new
species, and a new species of a H exagonaria-like genus.

PABLO CANYON AREA

A faulted slice of Roberts Mountains Formation oc-
curs in Pablo Canyon in the Toiyabe Range about 16
km west of the town of Round Mountain (fig. 1, loc. 12).
The top of the formation here is everywhere faulted,
and it is faulted at the base in most places. In the few
places where the basal chert unit is exposed, it lies on
3—6 m of shaly and cherty rock that contains Ordovi-
cian graptolites. Most of the formation is gray- to tan—
weathering thin-bedded platy-splitting silty limestone
typical of the graptolitic facies seen elsewhere in cen-
tral Nevada. The locality in Pablo Canyon is the west-
ernmost occurrence of recognizable Roberts Mountains
Formation at this latitude.

ROBERTS MOUNTAINS FORMATION IN THE
SHOSHONE MOUNTAINS

A partial section of Roberts Mountains Formation
crops out in the Shoshone Mountains in the Ravens-
wood area about 24 km northwest of Austin (fig. 1, loc.
17); the westernmost outcrops of the formation at this
latitude are almost directly north of the Point of Rocks
and Pablo Canyons sections along long 117°15’W.
The formation here, as at the other places at this gen—
eral latitude, is mostly graptolite-bearing thin-bedded
platy-splitting silty limestone. About 250 m of rocks of
this lithologic type occurs above a thin black chert-
bearing unit that in turn lies on either Middle Ordovi-
cian Antelope Valley Limestone or shale, chert, and
limestone of an unnamed unit tentatively correlated
with the Copenhagen Formation (Stewart and McKee,
1976).

SILURIAN AND LOWER DEVONIAN
LIMESTONES OF THE NORTHERN
INYO MOUNTAINS, CALIF.

MAZOURKA CANYON
VAUGHN GULCH LIMESTONE

Within the intermediate limestone belt, the south-
ernmost Silurian and Lower Devonian rocks of the
Great Basin crop out at Mazourka Canyon, northern
Inyo Mountains, Calif. (fig. 1, loc. 29). No exposures of
these limestones have been found between the Inyo

 

25

Mountains and the Toquima or Toiyabe Ranges, a dis—
tance of about 200 km. Named the Vaughn Gulch
Limestone by Ross (1963, p. B81), these beds were for
many years after their first geologic examination in
1912 believed to be entirely Devonian (Kirk, 1918;
Stauffer, 1930). Geologic mapping of the Cerro Gordo
mining district by the US. Geological Survey in 1946
stimulated renewed interest in these limestones when
it was suspected that the Silurian and Lower Devonian
Hidden Valley Dolomite (McAllister, 1952) of the
southern Inyo and Panamint Mountains changes
northward and westward to limestone as represented
at Mazourka Canyon. Systematic collecting and study
of the Vaughn Gulch and Hidden Valley Rugosa and
dasycladacean algae began in 1947 with the Cerro
Gordo work, during which the Vaughn Gulch section
was measured and mapped. A study of these rocks by
Waite (1953) pointed to the Silurian age of most of the
formation and demonstrated northward facies changes
into more argillaceous graptolite-bearing beds in the
Mazourka Canyon area. Detailed geologic mapping of
the Independence quadrangle by Ross (1968, 1965,
1966) further clarified the stratigraphic and structural
relations, and work by Stevens and Ridley (1974)
brought forth additional field evidence of northwest-
ward change to graptolitic facies within the Vaughn
Gulch. Correlation of the Vaughn Gulch with the
Roberts Mountains Formation was made possible by
comparative studies of its rugose corals and dasyclada-
cean algae in the 60’s. Stratigraphic details and fossil
zonation as here presented came mainly from Mer-
riam’s field investigation during the years 1946—48
when most of the fossil collecting was done by the US.
Geological Survey.

PHYSICAL STRATIGRAPHY

The Vaughn Gulch Limestone, in its type section,
the ridge northwest of Vaughn Gulch near the mouth
of Mazourka Canyon 4 km northeast of Kearsarge
(Ross, 1963, 1966), is an unbroken sequence about
460 m thick resting conformably upon the Late Or-
dovician Ely Springs Dolomite and overlain uncon-
formably by Mississippian conglomerate and quartzite
of the Perdido Formation (McAllister, 1952, p. 22). The
formation consists of well—bedded medium- to dark—gray
impure carbonaceous limestone, argillaceous lime—
stone, and calcareous siltstone including many fossil-
rich beds. Some of the more argillaceous and silty
interbeds weather in subdued fashion, becoming light
gray, stained pink, or orange in places. Black chert
zones are stratigraphically significant, occurring at the
base and top of the formation; elsewhere minor chert is
present as scattered nodules or thin lenses. Platy and
flaggy exposures predominate, with limestone ranging

26

from 2.5 to 15 cm separated by calcareous shaly or
siltstone partings. Thicker limestone beds, some ex-
ceeding 1 m, are fairly common; many of them are
coarsely bioclastic. These thicker beds weather out
prominently and are most numerous in the middle part
of the formation.

As noted by Ross (1966, p. 31), readily mappable
lithologic subdivisions were not found within the
Vaughn Gulch Limestone of the type section. Its faunal
distribution, however, is conveniently subdivided into
a lower part 107 m thick, a middle part 220 m thick,
and an upper part 140 m thick.

Lower division of the Vaughn Gulch Limestone.—
This part of the formation, about 107 m thick, consists
largely of platy to flaggy partly laminated dark-gray to
bluish-gray argillaceous limestone weathering light
gray in places. It is more uniformly bedded with fewer
bioclastic and fossil beds than higher parts of this for-
mation. A persistent dark-gray chert member at the
bottom, about 5 m thick, corresponds to that occurring
near the base of the Silurian System elsewhere in the
Great Basin. Weak partial dolomitization and nodular
chert decrease upward to the lowest fossil bed of Great
Basin Silurian coral zone A, which lies 40 m above the
basal cherty beds. The few fossil beds in this division
contain abundant Heliolites and favositids; more dis-
tinctive zone indicators like Dalmanophyllum are un-
common.

Middle division of the Vaughn Gulch Limestone.—
The 220 m of limestone constituting the middle part of
the Vaughn Gulch Limestone includes prominent
medium- to dark-gray richly fossiliferous coralline and
bioclastic beds in its upper half, of which the upper-
most 100 m falls within Great Basin Silurian coral
zone E. The dark-gray bioclastic beds range from 25 cm
to more than 1 m and are commonly sculptured into
prominent ribs separated by subdued intervals of
thin-bedded silty or argillaceous limestone weathering
a lighter gray. Much of the bioclastic material of these
thick fossil beds is crinoidal debris. Some of the fossils
that weather in relief are complete and partially
silicified and impregnated with limonite. Below the
middle of this 220 m division, the limestones are, in
general, thin bedded and show fewer bioclastic mem-
bers. No fossil accumulations with true biohermal re-
lief were found. Chert is a minor constituent. Some
100 m of beds in the middle of this 220-m division con-
tain an abundance of the large dasycladacean alga
Verticillopora annulata. Though long ranging, these
calcareous algae appear to be most numerous in the
Great Basin Silurian coral zone D.

Upper division of the Vaughn Gulch Limestone—A
140-m upper interval of the Vaughn Gulch Limestone
includes those beds between the top of Great Basin

 

ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

Silurian coral zone E and the Mississippian disconfor-
mity. Bioclastic beds within the topmost 25 m contain
an abundance of poorly preserved fossils. Contorted
layers of dark-gray chert in the upper 10 m are as-
sociated with massive dark-bluish-gray crinoidal lime-
stone with silicified partly macerated limonite-stained
brachiopods, favositids, and both solitary and colonial
large rugose corals. Below the upper beds, the lime—
stone is partly laminated and platy down to the lower
strata adjoining coral zone E where thicker bioclastic
and coralline beds become more numerous. Graptolite
and conodont evidence reported by Stevens and Ridley
(1974) indicate that the upper part of the formation is
Lower Devonian and probably as young as Middle De-
vonian.

STRATIGRAPH 1(1 PALEONTOLOGY

Large collections of fossils made by Stauffer (1930)
from limestone in what is now the type section of the
Vaughn Gulch Limestone are the basis for his com-
parison and correlation with the Kennett Formation of
northern California and assignment at that time of the
limestone to the Devonian System. The fossils were
meticulously zoned by Stauffer within a 500-m meas-
ured section comprising 14 numbered stratal units. In
general, these units can be alined fairly well with
those of the present measurement. As the Silurian and
Devonian Rugosa of western North America were un-
known at the time of Stauffer’s work, the listed iden-
tifications of these forms in the Vaughn Gulch have
little definitive significance by present standards.
Nonetheless, the bed-by-bed tabulations by Stauffer
clearly reflect the overall coralline nature of much of
the formation and reveal the diversity of these coral
assemblages. The lists show a relative abundance of
tabulate corals including massive F avosites, the slen-
der digitate Cladopora, and the less common Heliolites.
Stromatoporoids are listed throughout but do not ap-
pear to have been especially important as limestone
builders here. The spherical sponge Hindia is reported
in several beds. Brachiopod and trilobite identifica-
tions are largely of questionable value, no doubt partly
because the preservation is poor, and these fossil
groups are comparatively scarce in the coral-rich beds.
The abundant dasycladacean alga Verticillopora was
at that time unrecognized in these deposits.

The biostratigraphy of the Vaughn Gulch Limestone
as here presented is dependent upon study of the
rugose corals and dasycladacean algae. Great Basin
Silurian rugose coral zonation of Merriam (1973a),
treated elsewhere herein, is based upon combined
range and distribution data for these fossils in the
Roberts Mountains Formation, the Hidden Valley
Dolomite, and the Vaughn Gulch Limestone. The

LIMESTONES OF THE NORTHERN INYO MOUNTAINS

dasycladacean alga Verticillopora, which ranges up-
wards from Great Basin Silurian coral zone B to E and
above this horizon, is abundant and probably peaks in
coral zone D. Of the five Great Basin Silurian coral
zones A through E, only zones A and E have been iden-
tified with certainty in the Vaughn Gulch Limestone.

The Vaughn Gulch Limestone, judged by compara-
ble thicknesses and fauna, occupies most or all of the
stratigraphic interval of the Hidden Valley Dolomite
to the south and east. Great Basin Silurian coral zones
A and B are typified by distinctive rugose coral as-
semblages in the Hidden Valley, whereas zones C, D,
and E have their reference occurrences in the Roberts
Mountains Formation.

Coral zone A.—Great Basin Silurian coral zone A is
represented in the lower 107 m unit of the Vaughn
Gulch by beds containing the columellate solitary
rugose coral Dalmanophyllum sp. A, about 40 m above
the top of the basal chert marker units; also occurring
with the genus is a small tryplasmid, a pycnostylid
coral, favositids, Heliolites, and Camerotoechia. Other
zone A indicators like Palaeocyclus, Arachnophyllum,
and Cyathophylloides have not been found in the
Vaughn Gulch Limestone.

Verticillopora beds.—Strata in the middle part of the
220-m middle unit of the Vaughn Gulch contain an
abundance of the large Verticillopora annulata. This
algal genus ranges in decreasing numbers on up
through the overlying Great Basin Silurian coral zone
E into the lowermost beds of the upper 140-m unit of
the Vaughn Gulch, above which it has not been found.
Although the rugose coral fauna of Great Basin Silu-
rian coral zone D has not been found in the Vaughn
Gulch, it is not improbable that the beds in which Ver-
ticillopora annulata is most abundant occupy that
interval in which Silurian Verticillopora appears to
have peaked.

Coral zone E.—Great Basin Silurian coral zone E
occupies the uppermost 100-m interval of the middle
unit of the Vaughn Gulch Limestone. These upper beds
include units 12, 13, and 14 of Stauffer (1930, p. 86—
89). The large and diverse coral fauna contains an
abundance of tabulates including F avosites, Clado-
pora, Syringopora, and Heliolites, together with the
distinctive Silurian rugose corals Australophyllum
(Toquimaphyllum) sp. similar to A. johnsoni, Kypho-
phyllum sp., and Chonophyllum-like species. Rhizo—
phyllum sp. D Oliver is represented by float material,
doubtless from coral zone E, and probably by “Calceola
sandalina Lamarck” of the Stauffer list from his unit
12. Verticillopora ranges upward into coral zone E.
With this assemblage is the brachiopod Plectatrypa sp.
Crinoidal debris is abundant; the stromatoporoids,
though present, appear to be subordinate.

 

27

Stauffer’s rather lengthy faunal lists from the inter-
val of coral zone E include brachiopods, among them
Camarotoechia, Atrypa, Gypidula, Athyris, Tremato-
spira, Schizophoria, and Eatonia.

Fossils of the upper Vaughn Gulch Limestone.—
Except for the lowermost 8 m, the upper part of the
Vaughn Gulch Limestone has yielded few well-pre-
served fossils. The lowermost beds contain the highest
known Verticillopora, Australophyllum sp. v, and
Cladopora and other favositids. Near the top of the
formation at locality M1090 are poorly preserved
rugose and tabulate corals, large Atrypa, and indeter-
minate spiriferoid brachiopods. Among the Rugosa are
a large possible member of the Halliidae that resem-
blesAulacophyllum and a colonial genus that has fea-
tures of Acinophyllum or Diplophyllum. Other fossils
present are cystiphylloids, digitate and massive favo-
sitids, and stromatoporoids. Australophyllum sp. v re-
sembles A. landerensis of the central Nevada Rabbit
Hill Limestone of Early Devonian age. The diverse and
highly distinctive Rabbit Hill fauna has not been found
in this unit where it would be expected.

AGE

The age of the Vaughn Gulch Limestone, based on
its coral fauna, ranges from Early Silurian (Llandove-
rian) to possible Early Devonian. Dalmanophyllum sp.
A in the lower unit is an indicator of Great Basin Silu-
rian coral zone A. Beds with abundant Verticillopora
annulata in the middle of the middle lithologic unit of
the Vaughn Gulch probably bracket Great Basin Silu-
rian coral zone D although the rugose coral fauna of
zone D was not found in these strata, and it is probable
that Verticillopora reached its greatest development in
coral zone D. Great Basin Silurian coral zone E, at the
top of the middle unit, when compared with the Got-
land, Sweden, standard, is Late Silurian (late
Ludlovian).

In the absence of conclusive evidence from the coral
faunas, the upper lithologic unit of the Vaughn Gulch
is viewed as Late Silurian or Early Devonian. Aus-
tralophyllum sp. v at its base resembles, but is not
conspecific with, A. landerensis from the Lower Devo-
nian Limestone Rabbit Hill. Near the top is a large
Aulacophyllum-like coral, possibly of Early Devonian
age; the cystiphylloids and the Acinophyllum-like
coral might also be Devonian.

Graptolite and conodont evidence and correlation
with the Sunday Canyon Formation noted by Stevens
and Ridley (1974, p. 28) suggests that the formation
extends upward to the Middle Devonian.

Comparable thicknesses of the Vaughn Gulch Lime-
stone and the more easterly Hidden Valley Dolomite,
as well as stratigraphic relations with bracketing

28 ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

units strongly suggest that both occupy about the same
stratigraphic interval. Because of facies differences,
only Great Basin Silurian coral zone A has been recog-
nized. As shown by McAlIister (1952), the Hidden Val-
ley is largely of Silurian age and includes the reference
occurrences of Great Basin Silurian coral zones A and
B. The uppermost beds of this dolomite are of Early
Devonian age in the Siegenian-Emsian range. It is
probable that the highest Vaughn Gulch strata may be
correlative with the fossil-bearing part of the Hidden
Valley Dolomite. This correlation is made by Stevens
and Ridley (1974, fig. 2).

SUN DAY CANYON FO RMATK)N

The Silurian and Lower Devonian limestones of the
intermediate limestone belt change facies to shale lat-
erally within a relatively short distance in the Ma-
zourka Canyon area of the northern Inyo Range, Calif.
Detailed geologic mapping of the Vaughn Gulch Lime-
stone northward for 19 km toward Badger Flat by Ross
(1966) shows a progressive thinning of the formation
and the change to calcareous shale, siltstone, and ar-
gillaceous limestone. Tongues of Vaughn Gulch bio-
clastic limestone reappear north of the type section,
but within 8 km, near Barrel Spring, the general
character of the deposits has become such as to justify
the use of another name, Sunday Canyon Formation,

for rocks correlative with the Vaughn Gulch Lime:

stone. The more shaly facies continues northward
another 10 km to Badger Flat and becomes prog-
ressively thinner. How much of the thinning is due to
depositional processes such as initial deepening with
less sedimentation of open marine waters toward the
north and how much to erosional thinning at the un-
conformity with the overlying Mississippian is not
known. The calcareous shales yield mainly graptolites,
but occasional small Vaughn Gulch-type bioclastic
lenses as far north as Al Rose Canyon contain rugose
corals. In general, however, the proportion of carbo-
nate material decreases toward the north (Ross, 1966,
p. 32).
AGE
The age of the Sunday Canyon Formation has been

determined mainly by means of abundant monograp-
tids, nearly all collected near the base of the formation.
Among the species present are (identified by W. B. N.
Berry and R. J. Ross, Jr.):

Monograptus cf. M. dubius (Suess)

Monograptus dubius (Suess)

Monograptus sp. (the M. tumescens type)

Monograptus sp. (slender rhabdosomes,

thecae)
Monograptus sp. (the M. vulgaris type)
Monograptus cf. M. scanius Tullberg

plain

 

These forms suggest an age range in the Silurian from
Wenlock to Ludlow. A locality 45 m above the base of
the formation (USGS—D179—SD) yielded Monograptus
cf. M. uniformis Pribyl, which is considered to be Early
Devonian.

The problem of dating the Sunday Canyon is the
same as that relating to the Roberts Mountains For-
mation in that the standard time scale based on grap-
tolites is different than that based on corals and other
benthonic organisms and usually suggests relatively
younger ages for particular horizons. In the Mazourka
Canyon exposures, it is not unlikely that most of the
graptolitic deposits are relatively low in the Silurian
column.

The rugose coral Australophyllum stevensi Merriam,
from the upper 12 m of the Sunday Canyon, is of possi-
ble Early Devonian age.

Stevens and Ridley (1974), on the basis of graptolites
and conodonts, indicate that the formation extends to
the Middle Devonian.

THE SILURIAN-DEVONIAN BOUNDARY
IN CENTRAL NEVADA

We do not attempt here to delve into the philosophi-
cal aspects of stratigraphy with respect to time bound-
aries, lithofacies, biofacies, and systemic definitions.
Placement of the Silurian—Devonian boundary within
the carbonate sequence of the central Great Basin is a
problem when attempts are made to compare rugose
coral zonation based on similarities with the Gotland,
Sweden, sequence with graptolite zonation which is
the accepted guide for time boundaries in this part of
the geologic column. Any study of the Roberts Moun-
tains Formation should, however, point out the con-.
flict, where and how it arises, and what the current
geologic thinking is on this matter. This problem is a
classic one in stratigraphy involving lateral change of
facies, time-transgressive rock units, and definition of
time boundaries by faunas from different reference
sections at different places in the world. Specifically,
the Silurian-Devonian boundary is a troublesome
boundary that has been the subject of much discussion
and a number of international symposia beginning in
1958 and continuing to this time. The Silurian-
Devonian Boundary Committee of the International
Stratigraphic Commission has established a generally
accepted boundary which proves to be Viable in the
Great Basin and in most parts of the world. This
boundary is based on graptolites.

Placement of the boundary in many sections of lower
Paleozoic rock in central Nevada is difficult because geo-
logic structure is extremely complex and easily inter-
preted sequences of strata are rare. We point for exam-
ples to the section at Coal Canyon in the Simpson Park

STRATIGRAPHIC AND AGE VALUES OF RUGOSE CORALS

Mountains (see p. 11), which appears superficially to
be simple but contains at least one fault with uncertain
offset in a critical part of the section. Detailed mapping
is almost always a necessity before attempting strati-
graphic studies in this region, and frequently even
with careful mapping and repeated visits to the field,
the relation of rock units remains clouded. When the
geologic difficulties are added to the subtleties of
faunal interpretation in a narrow belt of rocks depos-
ited at the transition between shallow and deeper
water, one realizes why placement of the Silurian—
Devonian boundary has been disputed in this part of
the world. Part of the problem rests on what fossils are
available and what forms are used to define the
boundary—what yardstick we are measuring with.
When only one form is present, for example corals or
graptolites, the section can be matched with similar
standards elsewhere in the world. But, where more
than one form is present, as in central Nevada, and the
rocks have been correlated on the basis oflithology, the
faunal yardsticks do not agree. Several basic explana-
tions can account for this difference: various forms
have different time ranges at different places in the
world, or the standard sections such as that at Gotland,
Sweden, or the Dinant Basin, Belgium, do not contain
rocks wholly correlative. In central Nevada, the grap-
tolite Monograptus praehercynicus is used by Berry
(1970) to indicate the base of the Monograptus unifor-
mis Zone. This zone is considered by most members of
the Silurian-Devonian Boundary Committee of the In-
ternational Stratigraphic Commission to be the lowest
Devonian zone, and hence is accepted here as basal
Devonian although no agreement exists on precisely
what graptolite species or subspecies should be used to
denote the base of the zone. Monograptus praeher-
cynicus is found in the Roberts Mountains Formation
at a number of places, and in a few places it occurs in a
stratigraphic interval that also contains the coralline
fauna diagnostic of the Great Basin Silurian coral zone
E as defined by Merriam (1973a). In the central
Nevada limestone belt represented by the Roberts
Mountains Formation, the Silurian-Devonian bound—
ary based on graptolites and on conodonts is a hundred
metres or more lower in the same sequence of strata
than the boundary based on rugose corals and cal-
careous algae.

AN APPRAISAL OF STRATIGRAPHIC
AND AGE VALUES'OF RUGOSE CORALS AND
ASSOCIATED FOSSILS, WITH DESCRIPTION
OF PREVIOUSLY UNKNOWN KEY RUGOSA

Most of the Cordilleran Rugosa listed and referred to
in this report as related to the age and correlation of
Great Basin Silurian rocks of the intermediate lime-

 

29

stone belt are described in papers by Merriam (1972;
1973a) and a paper by Oliver, Merriam, and Churkin,
(1975).

With continued geologic mapping, new Silurian
rugose corals have since been discovered in the central
Great Basin, and other Rugosa previously unknown in
certain assemblages have been found in association at
new localities. The stratigraphic ranges of some genera
and species have been extended by further collecting
and stratigraphic investigation.

Recent researches upon little-known taxonomic
groups of Rugosa have resulted in a greatly improved
understanding of their internal structure, their value
as indicators of the Silurian and Devonian Systems,
and their geologic ranges. The two principal groups of
corals are those lacking dissepiments (nondissep-
imented corals) and those having dissipiments (dis-
sepimented corals). The nondissepimented Rugosa
with which we are concerned are the Family Kodono-
phyllidae, the Family Pycnostylidae, and the Family
Tryplasmatidae. The dissepimented Rugosa of special
interest here are the Family Spongophyllidae, includ-
ing the new colonial genus Carlinastraea. Others of
interest are assigned to the Family Endophyllidae, like
the subgenus Australophyllum (Toquimaphyllum) and
other forms of Australophyllum. Among the Family
Kyphophyllidae, there are new and undescribed
species of Kyphophyllum.

The dasycladacean algal group including Verticil-
lopora is discussed briefly; insofar as known, this large
and complex alga commonly associated with Silurian
Rugosa ranges upward only into the lower part of the
Devonian System.

RUGOSE CORALS OF SPECIAL STRATIGRAPHIC VALUE
SILL'RIAN NONIHSSEPIMENTED RUGOSA
Family KODONOPHYLLIDAE

The Family Kodonophyllidae, which so far as known
is confined to the Silurian of the Great Basin, com-
prises solitary and colonial nondissepimented Rugosa
having long lamellar septa, a very wide stereozone,
and flat tabulae or distally arched tabellae that may
combine with septal tips to form an axial structure and
calicular boss.

Two subfamilies of Kodonophyllidae are recognized:
Kodonophyllinae and Mycophyllinae. These sub-
families and their taxonomy have been discussed in
some detail by Merriam (1973a).

The genus Kodonophyllum Wedekind is present in
the Late Silurian (Great Basin Silurian coral zone E)
on the east side of the Coal Canyon fault, where it is
represented by the large Kodonophyllum mulleri Mer-
riam (pl. 4, figs. 5, 6). Kodonophyllum sp. b (pl. 5,

30

figs. 22~24), described below, occurs in the middle
coral-brachiopod zone at Bootstrap Hill, Tuscarora
Mountains.

Subfamily KODONOPHYLLINAE Merriam

Members of the subfamily Kodonophyllinae Mer-
riam are very thick walled fasciculate colonial and
platelike solitary Rugosa having the characteristics of
the family Kodonophyllidae. The tabulae and tabellae
arch distally, combining with septal ends to form an
axial structure and a calicular boss.

Kodonophyllum mulleri Merriam (1973a), of the
upper part of the Roberts Mountains Formation, is a
medium to large solitary coral with deep calice and
large calicular boss (pl. 4, figs. 5, 6). The major septal
count is about 48; septa, somewhat thickened through-
out, are excessively thickened in the wide peripheral
stereozone and in the axial structure, where they
are obscured by merging with stereoplasm and septal
terminations.

Kodonophyllum mulleri Merriam occurs in the
northern Simpson Park Mountains in the upper part of
the Roberts Mountains Formation; locality M1107,
Great Basin Silurian coral zone E.

Kodonophyllum sp. b
Plate 5, figures 22—24

Figured material.—USNM 166481. Roberts Moun—
tains Formation; Bootstrap Hill, Tuscarora Mountains,
Nev., locality M1314.

Diagnosis—Slender, subcylindrical Kodonophyllum
with axial arching of wide tabulae, moderate to low for
the genus.

Transverse thin sections.—Thick major septa
number about 24, most of which extend to the axial
structure. Minor septa buried in stereozone, which is
one-fourth of corallite diameter. Septal grooves are
broad and shallow. No discrete epitheca.

Longitudinal thin sections—Tabulae are rather
closely spaced, very uneven; many are complete, peri-
axially depressed, and rise nonuniformly toward axis.
Axial rise is moderate to low for this genus. Trabeculae
in Wide stereozone is steeply inclined outward.

Comparison with related forms.—Kodonophyllum
mulleri of the Roberts Mountains Formation is a
larger, more robust species with more numerous septa
than Kodonophyllum sp. b. It also has a more pro-
nounced axial rise of tabulae. K. truncatum (Linnaeus)
of the Gotland Silurian, a colonial form having
ceratoid corallites, has a somewhat wider stereozone
than the subcylindrical K. sp. b; otherwise features in
detailed thin-section resemble those of the Nevada
species.

Occurrence—Roberts Mountains Formation; south-
ern Tuscarora Mountains, Nev. Bootstrap Hill, locality

 

ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

M1314. In middle coral-brachiopod zone near bottom of
upper 275 m lithologic division.

The range of Kodonophyllum in the classic Gotland
Silurian column is Wenlockian to Ludlovian; occur-
rences in Great Britain are reported as Wenlockian. In
the Great Basin, the occurrence in coral zone E is late
Ludlovian, in the Tuscarora Mountains at Bootstrap
Hill in the middle coral-brachiopod zone, perhaps as
old as high Wenlock, but more likely Ludlovian.

Certain early Middle Devonian (Great Basin Devo-
nian coral zone D) occurrences of Kodonophyllum-like
corals of the Nevada Formation (Grays Canyon Lime-
stone Member of the Eureka area) have the very wide
peripheral stereozone of Kodonophyllum; the longitud-
inal features are unknown. These forms are probably
aberrant developments from the Siphonophrentis
(Breviphrentis) group that is characteristic of Great
Basin Devonian coral zone D (Merriam, 1973c).

Subfamily MYCOPHYLLINAE Hill
Genus Mucophyllum Etheridge

Members of the subfamily Mycophyllinae, charac-
terized by large discoid to turbinate corallites with a
broad calicular platform and a flat-bottomed central
pit, are especially characteristic of the Silurian. Septa
are numerous and thick and in contact laterally form-
ing a wide, thick stereozone. Tabulae are complete and
straight to undulant. Longitudinal sections show the
fine incremental layering of a very thick stereoone
transected by nearly vertical trabecular pillars.

Schlotheimophyllum of the Gotland Silurian has a
similar growth habit but differs by having a more com-
plex axial structure, more like that of Kodonophyllum.
M ucophyllum is known from Australia and from the
Klamath Mountains, Calif. All occurrences are in Silu-
rian deposits of late Wenlockian to Ludlovian age.
Mucophyllum oliveri (pl. 4, figs. 1—4) has near-
horizontal and undulant tabulae that are thickened
where merging with the longer septa. M. oliveri comes
from the east block of the Coal Canyon fault at Coal
Canyon, northern Simpson Park Mountains, in the
upper part of the Roberts Mountains Formation; local-
ity 1108; Great Basin Silurian coral zone E.

Family STREPTELASMATIDAE Nicholson
Genus Brachyelasma Lang, Smith, and Thomas

Simple, solitary, nondissepimented Rugosa with
partly complete tabulae ranges from Late Ordovician
into the Silurian of the Great Basin. The tabulae bend
downward as they approach the wall. Major septa do
not reach the axis, though they commonly extend more
than half that distance. Some species have a fossula.

Brachyelasma resembles the Devonian Breviphren-
tis, which has a wider stereozone and undergoes re-

FAMILY PYCNOSTYLIDAE STUMM

peated rejuvenescence to form long segmented coralla
not found in Brachyelasma.

Two species of Brachyelasma occur in the Roberts
Mountains Formation. Brachyelasma sp. c (pl. 5, figs.
25, 26) comes from locality M1383 in the lower coral
beds of the west fault block at Coal Canyon, Simpson
Park Mountains; Brachyelasma sp. b (pl. 12, figs.
29—33) is from locality M1120 at Bootstrap Hill, Tus-
carora Mountains, in the lower coral-brachiopod zone
with Cyathophylloides.

Family STAURIIDAE Edwards and Haime

Genus Cyathophylloides Dybowski

Cyathophylloides, a primitive colonial nondis-
sepimented rugose coral, is related to Favistella (0r
Favistina Flower) and to the phaceloid Palaeophyllum.
These corals are common in the Upper Ordovician, but
Cyathophylloides and Palaeophyllum range upward
into the Lower Silurian.

Cyathophylloides forms massive cerioid colonies
with narrow corallites having 12—14 smooth, simple
lamellar major septa that meet axially where they may
be twisted but do not form a discrete axial structure.
Tabulae are complete; minor septa are short to fairly
long. Cyathophylloides is represented in the Roberts
Mountains Formation by C. fergusoni Merriam of
Great Basin Silurian coral zone A in the Mill Canyon
sequence at Ikes Canyon, Toquima Range. A similar
species C. sp. f (pl. 12, figs. 27, 28) comes from the
lowermost coral-brachiopod zone at Bootstrap Hill
(locs. M1120, M1412).

Family TRYPLASMATIDAE Etherid ge

The family Tryplasmatidae, characterized by
spinose or acanthine septa, is especially common in
rocks of the Silurian System. Tryplasmids have been
reported in strata of the Devonian (Hill, 1956, p. F312;
Oliver, 1960, p. 15) and are known in Late Ordovician
rocks of Sweden. Reviews of the classification have
been published by Hill (1936) and by Merriam (1973a).
They are readily distinguished from the other nondis-
sepimented Rugosa that have wide complete tabulae
by their acanthine septa, and they do not have the wide
stereozone of the Kodonophyllidae or the multiple
interior calice offsets of the pycnostylids. The
Stauriidae-like Palaeophyllum of the Late Ordovician
and Silurian has medium to long lamellar septa.

The general characteristics of the tryplasmids are
well shown by the undescribed Gotland species Try-
plasma sp. g of the Hemse Group (Ludlovian) (pl. 3,
figs. 16—19), T. newfarmeri Merriam (pl. 3, figs. 10—15)
of Great Basin Silurian coral zone C, and T. duncanae
Merriam (pl. 3, figs. 8, 9) of Great Basin Silurian coral
zone D.

 

31

Family PYCNOSTYLIDAE Stumm

Pycnostylid rugose corals are among the most abun-
dant and distinctive nondissepimented genera in cer-
tain facies of the Silurian System. It is possible these
corals have Devonian descendants like Cyathopaedium
and Fletcherina. None are known in rocks of Late
Ordovician age.

The pycnostylids are colonial fasciculate Rugosa
having subcylindrical corallites. The septa are very
short and vertically continuous, or lacking. The stereo-
zone is narrow. Most tabulae are complete and un-
arched medially. There are no dissepiments. Reproduc—
tion is by multiple offsets peripherally from the calice
interior.

The Silurian genera are Pycnostylus Whiteaves,
Stylopleura Merriam, and Fletcheria Edwards and
Haime. Cerioid colonial genera like Maikottia Lav-
rusevitch and similar large undescribed genera from
the Roberts Mountains Formation are provisionally
assigned to this family.

The taxonomy of the Pycnostylidae has been treated
in some detail by Merriam (1973a).

Genus Pycnostylus Whiteaves

With the type species Pycnostylus guelphensis Whit-
eaves of the Guelph Dolomite, Guelph, Ontario, (pl. 1,
figs. 16—19), Pycnostylus is characterized by only four
internal calice offsets or peripheral offsets. Pycnostylus
elegans Whiteaves probably has a greater number of
offsets (pl. 1, fig. 20). Pycnostylus is not known to pos-
sess the lateral connecting elements of Stylopleura.

Several poorly known Asiatic and Australian corals
referred to by Hill (1940) as "ampleximorphs” are
doubtfully related to Pycnostylus. These corals are re-
ported to have amplexoid lamellar septa. Several
little-known Silurian corals of similar character have
been classified as Pycnostylus by Hill (1940) as
Amplexus by Grabau (1930) and by Shimizu, Ozaki,
and Obata (1934), and asAmplexoides by Wang (1947).

Pycnostylus Whiteaves is probably not a junior syn-
onym of F letcheria Edwards and Haime as interpreted
by several workers. Fletcheria tubifera Edwards and
Haime from Gotland has no septa but it does have a
distinctive wall structure, and some of the tabulae (or
large tabellae) are distally convex (pl. 3, figs. 1-7).
Forms assigned by Norford (1962, pl. 15) to Fletcheria
are probably best placed in Pycnostylus. A similar Pyc-
nostylus, Pycnostylus sp. 1 (pl. 2, fig. 10), occurs in the
Lone Mountain Dolomite but has not been found in the
Roberts Mountains Formation.

Genus Stylopleura Merriam
The genus Stylopleura with type species S. berthi-
aumi Merriam (1973a), which was first found in the
upper part of the Roberts Mountains Formation unit 3,

32

is a phaceloid to cerioid coral. It differs from Pycno-
stylus by having a large number of subequal peripheral
offsets of internal calice offsets and long tubular-
connecting elements between corallites. Open bushy
forms have trumpet-shaped flaring calices.

Of the described species of Stylopleura, Stylopleura
berthiaumi of Great Basin Silurian coral zones D and E
(pl. 1, figs. 1—9; pl. 2, figs. 8, 9) has a more open
phaceloid construction with flaring calices than the
other species. S. nevadensis of Great Basin Silurian
coral zone E (pl. 2, figs. 3—6) tends to be of more
crowded phaceloid to subcerioid compact construction
with fewer lateral elements. Also found is Stylopleura
cf. S. nevadensis, n. gen., n. sp. (pl. 2, fig. 7.)

Stylopleura sp. b
Plate 1, figures 10—12

Stylopleura sp. b, known from isolated fragmentary
corallites at Bootstrap Hill, Tuscarora Mountains, re-
sembles S. berthiaumi, but the specimens in the collec-
tion do not include those with reproductive calices. The
long tubular connecting processes are well shown.

Stylopleura sp. b occurs at localities M1314 and
M1315 in the middle coral-brachiopod zone of the
Roberts Mountains Formation at Bootstrap Hill, where
it is associated with Kodonophyllum sp. b, Kypho-
phyllum sp. b, and Calostylis? sp.

Stylopleura. sp. 0, of. S. berthiaumi Merriam
Plate 1, figures 13—15

Stylopleura sp. c, cf. S. berthiaumi is a fairly compact
phaceloid Stylopleura from the lower coral zone of the
west block of the Coal Canyon fault at Coal Canyon,
northern Simpson Park Mountains. It has the multiple
calice offsets but none of the lateral connecting ele-
ments of S. berthiaumi. This form occurs here in the
same beds with Carlinastraea tuscaroraensis and Ton-
kinaria simpsoni Merriam and is accordingly regarded
as an occupant of the approximate interval of Great
Basin Silurian coral zone D.

COMPACT (IICRIOID PYCNOSTYLIDAE OF SILURIAN
LIMESTONE FACII‘ZS

Unusually large phaceloid to cerioid Rugosa lacking
multiple peripheral offsets and resembling Stylopleura
nevadensis Merriam are known from Late Silurian
limestones of the Cordilleran belt. Being compact or
appressed, these specimens do not show lateral con-
necting elements. Some, like Stylopleura? sp. T (Mer-
riam, 1973a), have very wide corallites, a very thick
wall, and closely spaced tabulae; others, like the large
aseptate pycnostylid Stylopleura? sp. 0 from Coal Can-
yon in the Simpson Park Mountains, have a very thin
wall without septa. The septate forms have short lon-
gitudinally continuous septa.

 

ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

Corals provisionally assigned to this informal group
are Maikottia sp., cf. M. turkestanica Lavrusevich of
the Porcupine River, Alaska (Merriam, 1973a), Sty-
lopleura? sp. T of the Ikes Canyon area, Toquima
Range, Nev., and the compact thin-walled aseptate
pycnostylid species Stylopleura? sp. c from Coal Can-
yon, Simpson Park Mountains, here described.

Stylopleura? sp. 0
Plate 2, figures 1, 2

Stylopleura? sp. c is a large compact species. Coral-
lites are as much as 24 mm wide and have a very thin
straight wall. Septa are absent. Tabulae are closely
spaced, uneven, and have a pronounced sag axially.
Most tabulae are entire, but some near the periphery
are short and terminate against a complete tabula. The
similarity of this form to the Australian Silurian
Yassia Jones in longitudinal section is deceiving, as it
lacks the dissepiments of Yassia in the strict sense.

Occurrence.—A single incomplete corallum from
Coal Canyon, Simpson Park Mountains, Nev., locality
M1379, in sheared Roberts Mountains limestone at the
west edge of the Coal Canyon fault zone.

DISSEI’IMI‘INI‘EI) RL'GOSA OF THE. GREAT BASIN
SILL'RIAN I.I‘.\'IES'I‘OT\'I{ FACIES

Rugose corals with dissepiments, uncommon in the
Cordilleran Late Ordovician, had become abundant by
mid-Silurian time with the appearance of the lyko-
phyllids, Entelophylloides, Petrozium, and other gen-
era. Several Late Silurian colonial dissepimented
groups disappeared by the end of the Silurian or the
earliest Devonian, and new ones appeared in early
Middle Devonian time. Families of special importance
in the Late Silurian of the Great Basin intermediate
limestone belt are the Spongophyllidae and the En-
dophyllidae.

Family SPONGOPI—IYLLIDAE Dybowski
Genus Carlinastraea, n. gen.

Type species.—Carlinastraea tuscaroraensis n. gen.,
n. sp., here designated; Late Silurian, upper beds of the
Roberts Mountains Formation, Nev.

Diagnosis.-—Cerioid spongophyllid having slender,
fairly thick walled corallites, a strong marginarium of
large to very large, steeply inclined lonsdaleioid dis-
sepiments, and a nonuniform pattern of partially
aborted septa in the tabularium of some corallites.

Remarks—Direct comparison of Carlinastraea with
the most nearly related genus, Spongophyllum Ed-
wards and Haime, is not possible as the Edwards and
Haime (1853) type material of S. sedgwicki (the type
species) has been lost and only the original published
illustrations (pl. 6, figs. 1—4) remain as a basis for

FAMILY SPONGOPHYLLIDAE DYBOWSKI

reappraisal. These illustrations (Edwards and Haime,
1853, pl. 56, figs. 2, 2a—2e) with little doubt figure two
different corals: (1) group 1 (pl. 56, figs. 2d, e), a thin-
walled genus having many small peripheral
lonsdaleioid dissepiments, (2) group 2 (pl. 56, figs. 2,
2a—2c), a genus having narrower, moderately thick-
walled corallites, lacking or nearly lacking conspicu—
ous lonsdaleioid dissepiments. It is not likely that the
two forms fall within the range of variation of a single
genus and species; so far this possibility is unknown.
The usually accepted characterization of Spongophyl-
lum is that of lonsdaleioid group 1, and it is with this
group that Carlinastraea is compared. Comparison of
Spongophyllum sedgwicki to Lonsdaleia by Edwards
and Haime (1851, p. 425; 1853, p. 242) is further evi-
dence that the original diagnosis is that of a cerioid
rugose coral with well-developed lonsdaleioid dissepi-
ments.

It is unfortunate that Jones (1929, p. 89) selected as
the “neotype” of Spongophyllum sedgwicki a float
specimen in "a dark coloured pebble” from "South
Devonshire.” Although not figured by Jones in 1929,
thin sections of this “neotype” were illustrated by
black and white drawings by Birenheide (1962, p.
68—74, pl. 9, fig. 8, pl. 10, fig. 10). The Birenheide
figures show a coral without conspicuous lonsdaleioid
dissepiments, agreeing reasonably well with non-
lonsdaleioid group 2 of the Edwards and Haime type
illustrations.

Comparing Carlinastraea with group 1 lonsdaleioid
Spongophyllum of Edwards and Haime, the new genus
Carlinastraea differs by having a much thicker wall
with strong wall crests and all corallites have much
larger lonsdaleioid dissepiments. The septa of Car-
linastraea, being less continuous radially than those of
Spongophyllum sedgwicki, are marked peripherally by
septal crests. Aborting of septa, a feature of Carlina—
straea, is unknown in S. sedgwicki. Mature corallites
without lonsdaleioid dissepiments, as in group 2 of the
Edwards and Haime S. sedgwicki, were not observed.

Carlinastraea tuscaroraensis n. gen., n. sp., occurs in
the upper part of the Roberts Mountains Formation. As
recorded by Edwards and Haime, the Spongophyllum
types came from Devonian strata of Torquay, Devon-
shire, England. The Jones-selected neotype, being a
float cobble, fails to confirm this occurrence. Recent
studies of southern England Devonian Rugosa by
Taylor (1950), Middleton (1959), and Webby (1964)
make no reference to Spongophyllum. Two species of
Spongophyllum (sp. A and sp. B) have been reported
from the McCann Hill Chert of Alaska by Oliver (in
Oliver and others, 1975); he considered it to be Early(?)
to Late Devonian (Emsian? to Frasnian). Elsewhere in
the Cordilleran belt of western North America, there

 

33

are no records of strongly lonsdaleioid cerioid Devo-
nian corals that closely resemble group 1 of S.
sedgwicki or the new genus Carlinastraea.

Species from the Ural Mountains, USSR, assigned to
Spongophyllum by Shurygina (1968) are herein as-
signed to the new genus Carlinastraea. Shurygina
(1968, p. 121—135, pl. 59, figs. 1—3) reported these ques-
tionable species as Lower Devonian. The coral fauna
that is included with Spongophyllum [Carlinastraea]
by Shurygina in these Ural beds is more suggestive of
the forms in the Late Silurian of Gotland. Among the
genera from the Urals so listed are Spongophylloides,
Tryplasma, Neomphyma, and Rhizophyllum. Also in-
cluded is Salairophyllum, which in southeastern
Alaska occurs with the large Late Silurian Con-
chidium alaskense and, at Coal Canyon, Simpson Park
Mountains, Nev., occurs as float, doubtless from high
beds of the Roberts Mountains Formation.

Carlinastraea tuscaroraensis n. gen., n. sp.
Plate 6, figures 5—7; plate 7, figures 1—4

Type and figured specimens.—Holotype USNM
166482, upper beds of the Roberts Mountains Forma-
tion, locality M1313, Bootstrap Hill, Nev. Figured
specimens USNM 166483, locality M1384, Coal Can-
yon, NeV.; USNM 166484, locality M1409, Cortez, Nev.

Diagnosis.—Large massive Carlinastraea. The
coralla have several hundreds of very narrow corallites
whose septa are marked peripherally by strong wall
crests; septa are mostly thin, nonuniform, and irreg-
ularly wavy; the largest lonsdaleioid dissepiments sub-
tend one-fifth of a corallite circumference.

Transverse thin sections.—Wall is stereoplasmically
thickened, has about 26 prominent, mostly obtuse wall
crests uniformly spaced. Major septa are thin, smooth,
unevenly wavy, nonuniform, and number 12—14—the
longest reach the axis; septal crests are developed, per-
ipherally in some corallites. Lonsdaleioid dissepiments
number 6 to about 10 in a peripheral cycle and vary
greatly in size; the largest subtend one-fifth of the
corallite circumference. Minor septa, weakly de-
veloped, show as wall crests and sporadic outer septal
crests.

Longitudinal thin sections.—Tabularium is less than
one-fourth to more than one-third of corallite width;
delicate tabulae are only in part complete, sag irregu-
larly proximally, and for the greater part are rather
closely spaced. Lonsdaleioid dissepiments, predomi-
nantly large with very steep axial inclination, are ar-
ranged in one to three columns on each side.

Fine structure.—Stereoplasmic wall is without dis-
crete trabeculae and shows very fine calcitic fibers
transversely oriented; faint lamellar texture in some
places is developed toward inner wall surface.

34

Comparison with related forms.—Carlinastraea
giganteum (Shurygina) of the Ural Mountains, USSR
(Shurygina, 1968, p. 135, pl. 59, figs. 1, 2), differs from
the new species by having less developed wall crests,
straighter septa, and less steeply inclined lonsdaleioid
dissepiments. Carlinastraea originalis (thaev), also
of the Urals (Shurygina, 1968, p. 134, pl. 59, figs. 3a—b),
has less developed wall crests and more aborted septa
than C. tuscaroraensis.

Occurrence—Upper part of the Roberts Mountains
Formation, northern Simpson Park Mountains, Nev.:
locality M1384, Coal Canyon, west side in beds with a
fauna believed to represent Great Basin Silurian coral
zone D. Tuscarora Mountains, Nev., locality M1313,
Bootstrap Hill. Carlinastraea cf. C. tuscaroraensis,
Cortez Mountains, Nev., locality M1409, pl. 8, figs. 1, 2.

Family ENDOPHYLLIDAE Torley
Genus Ketophyllum Wedekind

The solitary genus Ketophyllum is common in the
Silurian of Gotland, Sweden, and in eastern Europe.
Only fragments of Ketophyllum sp. t (pl. 10, figs. 18,
19) have been collected by McKee in the Toquima
Range, Nev. Some species ofKetophyllum are Virtually
indistinguishable from the Devonian Tabulophyllum
except for the presence ofa weak fossula in some forms
of Ketophyllum (Wedekind, 1927); this structure is
usually not visible in Tabulophyllum. Both have a very
Wide tabularium and closely spaced straight to some-
what undulant tabulae, many of which are complete.
Both genera have a peripheral band of large lonsdale-
ioid dissepiments, and the thin septa break up periph-
erally as septal crests.

Ketophyllum sp. t occurs in the Toquima Range at
locality M1393 in the Mill Canyon sequence on the
south side of Ikes Canyon a mile northwest of the
canyon mouth.

Genus Australophyllum Stumm

Large colonial heads of Australophyllum are com—
mon in Great Basin Silurian coral zone E, where it is
represented by the subgenus Australophyllum (To-
quimaphyllum). Other forms of Australophyllum
sensu stricto occur in the same uppermost beds of the
Silurian limestone facies and, though sparsely repre-
sented, range upward into the Lower Devonian Rabbit
Hill Limestone. Some Middle Devonian species that
were referred to Australophyllum in the past have but
few sporadic lonsdaleioid dissepiments and are
perhaps best assigned to other genera. The
lonsdaleioid subgenus Toquimaphyllum has a
worldwide geographic distribution. A similar form oc-
curs to which the generic name Klamathastraea has
been given (Merriam, 1972) in Late Silurian beds of

 

ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

the Gazelle Formation, Klamath Mountains, Calif.
K lamathastraea differs from Toquimaphyllum by hav—
ing a much wider tabularium, tabulae with a marginal
depression, and a pronounced tendency to abort septa
in mature growth stages.
Australophyllum (Australophyllum) sp. c
Plate 8, figures 3—7

Diagnosis—Large Australophyllum with corallites
of greatly varying width; lonsdaleioid dissepiments are
in restricted peripheral patches only; tabulae closely
spaced, in places crowded; septa are minutely wavy
with spines and bumps in the periaxial band.

Transverse thin sections.—Corallites, highly var-
iable in size, range in diameter from 9 to 28 mm at the
same distal corallum surface. Septal count is about 62
in large corallites. Major septa reach the axis and are
twisted near it; minor septa range from one-half to
three-fourths length of major septa. Septa, locally
thickened in dissepimentarium, may be slightly thick-
ened in tabularium, wherein they become minutely
wavy and ornamented laterally with spines and nodes.
Narrower corallites show stereoplasmic wall thick-
ening. Some larger lonsdaleioid patches quite irregu-
lar.

Longitudinal thin sections.—Tabularium width is
one-fourth to one-third of corallite diameter. Dissepi-
ments are medium to large in as many as nine columns
on each side of wider corallites. Outer dissepiments are
much less steeply inclined than inner ones. Tabulae
are mostly close spaced or crowded; many are complete
with a wavy proximal sag. Inner septal extensions
have numerous lateral spines and bumps.

Comparison with other forms.—Australophyllum
(Toquimaphyllum)johnsoni Merriam of Great Basin
Silurian coral zone E has a much more continuous and
uniform marginarium of lonsdaleioid dissepiments
that are less steeply inclined; its tabularium is nar-
rower than that of Australophyllum sp. c. Australa-
phyllum landerensis Merriam has fewer septa, a more
fully developed pattern of lonsdaleioid dissepiments,
and fewer lateral spines and bumps on axial extensions
of septa. Australophyllum sp. v of Late Silurian and
Early Devonian beds in the Vaughn Gulch Limestone
has a similarly restricted pattern of lonsdaleioid dis-
sepiments but it differs by having narrower, thicker
walled corallites and fewer septa; the septa are un-
thickened and lack the abundant lateral spines and
nodes of Australophyllum sp. c. A similar coral from
locality M1445 near the Big Six mine, Tuscarora
Mountains, has the spiny septal extensions of Aus-
tralophyllum sp. c but has very few small lonsdaleioid
dissepiments and a thicker wall. The Tuscarora Moun-
tains coral also differs by having localized crossbar
carinae.

FAMILY ENDOPHYLLIDAE TORLEY

Occurrence—Coal Canyon, Simpson Park Moun—
tains; locality M1318 in Coal Canyon fault zone on
west side of canyon. Although this coral head was not
collected in place and the locality is in deformed strata
within the fault zone, its field location suggests that it
may have come from beds stratigraphically above the
lower Carlinastraea coral beds of the west fault block.

Australophyllum (Australophyllum) sp. v
Plate 8, figures 8—11

Diagnosis—Australophyllum has predominantly
narrow, fairly thick-walled corallites and a restricted
pattern of lonsdaleioid dissepiments; septa are mostly
thin with very few nodes and spines in periaxial band.

Transverse thin sections.—Septal count is about 42
in average corallites. Some major septa reach axis;
minor septa, mostly less than half the length of the
major septa, commonly appear only as septal crests
peripherally. Septa are slightly wavy. Lonsdaleioid
dissepiments are medium and small and are restricted
or absent in some corallites.

Longitudinal thin sections.—Tabularium is one-
third to less than one-fourth of corallite diameter;
tabulae are partly complete, closely spaced, and sag-
ging. Dissepiments are steeply inclined, 4—7 columns
on each side. Periaxial extensions of septa are nearly
devoid of nodes and spines. Thickened wall shows no
discrete trabecular structure.

Comparison to related forms.—Austral0phyllum sp.
v is most closely related to A. landerensis Merriam
from Lower Devonian beds of the northern Toquima
Range, Nev. The Devonian form differs by having
somewhat thickened and more wavy septa in the
tabularium; the periaxial extensions of septa show
more lateral nodes and bumps than in A. sp. v. Aus-

tralophyllum sp. c has scattered, much wider coral-'

lites with a septal count of 62, and its periaxial septal
extensions show abundant lateral spines and nodes.
Occurrence and age.—Mazourka Canyon, northern
Inyo Mountains, Calif; upper middle and upper beds of
the Vaughn Gulch Limestone. Locality M1093, bottom
of the upper unit of the Vaughn Gulch Limestone of
Late Silurian and Early Devonian(?) age. Locality
M1410 about 50 feet stratigraphically below M1093.

Subgenus Toquimaphyllum Merriam

(subgenus of Australophyllum Stumm)
Toquimaphyllum, a cerioid compact subgenus of
Australophyllum, has a wide continuous marginarium
of predominantly large lonsdaleioid dissepiments; the
peripheral dissepiments are nearly flat or dip axially
at low angles. The tabularium is narrow to moderately
wide; the tabulae are closely spaced, sagging, and are
without a marginal depression. The septa are thin,
smooth, fairly straight, and discontinuous peripherally

 

35

as septal crests. Some mature corallites have much
shortened or obsolete septa.

Australophyllum (Toquimaphyllum) differs from
Australophyllum sensu stricto by the greater develop-
ment of large lonsdaleioid dissepiments forming a con-
tinuous marginarium, by the presence of septal crests
peripherally, and by its tendency to lose septa in some
mature corallites. The septa of Toquimaphyllum lack
the carinae reported by Stumm (1949, p. 34) in Aus-
tralophyllum sensu stricto. Endophyllum differs by
having a much wider tabularium; the tabulae being
nearly flat to slightly arched medially with a periph-
eral sag. The type species ofEndophyllum shows a ten-
dency to lose the outer wall, thus becoming partially
aphroid. As known, Endophyllum does not, like To-
quimaphyllum, have a tendency to shorten and lose
septa.

Australophyllum (Toquimaphyllum) johnsoni Mer-
riam (pl. 6, figs. 8—10) is the most abundant and dis-
tinctive rugose coral of Great Basin Silurian coral zone
E (Late Silurian). The relations of this subgenus and
its worldwide distribution are discussed in some detail
by Merriam (1972a).

The type species Australophyllum (Toquimaphyl-
lum)johnsoni Merriam comes from the Roberts Moun-
tains Formation of the Mill Canyon sequence of the
Ikes Canyon area, Toquima Range, Nev. Much of the
study material was collected from the upper beds of
the Roberts Mountains Formation at Coal Canyon,
Simpson Park Mountains.

Australophyllum (Toquimaphyllum) johnsoni Mex-riam

Plate 6, figures 8—10

Collections from several localities in Silurian lime-
stones between the northern Simpson Park Mountains
and the northern Inyo Mountains of California contain
many complete and fragmentary colonies of this
species. Australophyllum (Toquimaphyllum)johnsoni
has been found only in strata of Great Basin Silurian
coral zone E. A detailed description of this species and
a review of its taxonomy have recently been published
by Merriam (1973a)

This species is characterized by wide corallites, the
major septa normally reach the axis and break up
peripherally as septal crests. Most mature corallites
have a narrow tabularium and a correspondingly wide
dissepimentarium in which the outer dissepiments are
nearly flat. Partially aseptate corallites show only
abbreviated tips of major septa. ‘

Occurrence—Upper beds of the Roberts Mountains
Formation in the Mill Canyon sequence at Ikes Can—
yon, Toquima Range; locality M1114 (type locality).
Upper beds of the Roberts Mountains Formation in
east block of Coal Canyon fault zone, Coal Canyon,
northern Simpson Park Mountains; several localities

36

including M1106 and M1108. Foothill exposures 2.4
km north of Red Hill, SE%NE% sec. 5, T. 25 N., R. 50
E., Simpson Park Mountains; locality M1446. Upper
part of middle unit of Vaughn Gulch Limestone (these
specimens differ slightly from typical A. johnsoni),
Mazourka Canyon, northern Inyo Mountains; locality
M1115. Australophyllum, possibly A.j0hnsoni, occurs
in the Antelope Peak section 19 km north of wells,
Elko County, Nev.

Family CHONOPHYLLIDAE Holmes
Genus Chonophyllum Edwards and Haime

Chonophyllum shares some characteristics of
K etophyllum and other members of the Endophyllidae,
but it is solitary and usually has a narrower tabular-
ium than most endophyllids. The lonsdaleioid pattern
of Chonophyllum is much more irregular or less un-
iform and localized in peripheral patches.

Chonophyllum simpsoni Merriam (pl. 7, figs. 5, 6;
pl. 9, figs. 9, 10) from the uppermost part of the Roberts
Mountains Formation is a large trochoid to ceratoid
species with major septa reaching the axis and a nar-
row tabularium. Its tabulae are closely spaced, undu-
lant, and mostly incomplete with marginal tabellae.
Inner dissepiments are commonly anguloconcentric in
transverse section.

Chonophyllum simpsoni Merriam occurs at locality
M1108 in the east block of the Coal Canyon fault, Coal
Canyon, Simpson Park Mountains, Nev., the upper
part of the Roberts Mountains Formation.

Family KYPHOPHYLLIDAE Wedekind

This large and somewhat heterogeneous provisional
group of Silurian Rugosa as revised by Merriam
(1973a) contains about eight genera as follows:

Kyphophyllum Wedekind

Strombodes Schweigger

Petrozium Smith

E ntelophyllum Wedekind

Entelophylloides Rukhin (as a subgenus)

Entelophylloides (Prohexagonaria) Merriam

Neomphyma Soshkina

?T0nkinaria Merriam.
Of these genera, Kyphophyllum and Tonkinaria are of
greatest importance to the stratigraphy of the inter-
mediate limestone facies.

Genus Kyphophyllum Wedekind

Kyphophyllum builds large bushy phaceloid c01—
onies; its subcylindrical corallites have a narrow
stereozone and medium-narrow closely spaced tabulae.
Restricted segments of the marginarium are occupied
by large, irregular lonsdaleioid dissepiments. In the
Roberts Mountains Formation and Vaughn Gulch
Limestone, this genus is represented by K. nevadensis
Merriam, K. sp. b, K. sp. c, K. sp. t, and other unde-

 

ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

scribed species. In the Great Basin, Kyphophyllum oc-
curs in Great Basin Silurian coral zone E (Late Silu-
rian).
Kyphophyllum nevac‘lensis Merriam
Plate 9, figures 1—3

Kyphophyllum nevadensis has medium-wide to nar-
row corallites of variable diameter with a small
number of major septa (about 22) and sporadic groups
of relatively large lonsdaleioid dissepiments.

Occurrence.—Ikes Canyon (Mill Canyon sequence),
Toquima Range, Nev. Great Basin Silurian coral zone
E. Locality M1114, northwest side of Copper Mountain
in lower part of the McMonnigal Limestone.

Kyphophyllum sp. b
Plate 5, figures 15—21

Kyphophyllum sp. b has very narrow corallites for
the genus, a few wavy major septa (about 20), very few
lonsdaleioid dissepiments, and lateral offsets that are
attached at former calice rims. The dissepiments are
all steeply inclined or vertical. Longitudinal exterior
ribbing is strongly developed.

Occurrence.—Tuscarora Mountains, Nev. Locality
M1314, middle part of the Roberts Mountains For-
mation.

Kyphophyllum sp. c
Plate 9, figures 4—8

Kyphophyllum sp. 0 has large corallites for the
genus and a large number (about 60) of long, smooth,
somewhat wavy septa, many of which are greatly
lengthened minor septa. Longitudinal sections of K.
sp. 0 are similar to those of K. nevadensis with a few
large localized lonsdaleioid dissepiments. Some coral-
lites are joined by lateral processes not observed in K.
nevadensis.

Occurrence—Coal Canyon, Simpson Park Moun-
tains, Nev. Locality M1380, upper part of the Roberts
Mountains Formation.

Kyphophyllum sp. 1;
Plate 10, figures 14—17

Kyphophyllum sp. t has narrow corallites of greatly
varying diameter. The larger corallites have about 20
long, somewhat wavy major septa and very short
minor septa. All dissepiments are steeply inclined. The
stereozone is relatively wide for this genus.

Occurrence.—Toquima Range, Nev. Late Silurian
and Devonian Tor Limestone of the June Canyon se-
quence; locality M1397.

Genus Tonkinaria Merriam
Tonkinaria, a solitary or loosely phaceloid genus,
commonly has a flaring trumpet-shaped calice, cera-
toid to turbinate corallites, and a narrow tabularium.
The wall is a narrow stereozone, the septa are thin, and

FOSSILS ASSOCIATED WITH RUGOSE CORALS

major septa reach or are slightly withdrawn from the
axis. Dissepiments are mostly large, elongate, and
steeply inclined. Multiplication is by peripheral calice
offsets, of which there may be several on a single flar-
ing calice rim.

Occurrence.——T0nkinaria simpsoni Merriam, the
type species, comes from locality M1100 (pl. 5, figs.
1-9) in Roberts Mountains Formation unit 3 and Great
Basin Silurian coral zone D of the reference section;
locality M1103 in the Mill Canyon sequence at Ikes
Canyon, Toquima Range, Nev., in Great Basin Silu-
rian coral zone D; and locality M1383 (pl. 5, figs. 10—14)
on the west side of Coal Canyon, Simpson Park Moun-
tains, where it occurs in the west block of the Coal
Canyon fault together with Carlinastraea tuscaroraen-
sis and Stylopleura.

Family CALOSTYLIDAE Roemer
Genus Calostylis Lindsti‘om

Fragmentary and rather poorly preserved solitary
rugose corals from Bootstrap Hill, Tuscarora Moun-
tains, are referred provisionally to Calostylis. This
Silurian genus occupies a peculiar relation to all other
Rugosa (Smith, 1930, p. 294) by possessing perforate
septa and a spongy axial structure.

Calostylis? sp. (pl. 7, figs. 7, 8) occurs at locality
M1314, Bootstrap Hill, Tuscarora Mountains, Nev., in
the middle part of the Roberts Mountains Formation.

Family LYKOPHYLLIDAE Wedekind

Solitary lykophyllid Rugosa have not been found to
be among the more abundant corals of the Great Basin
Silurian limestone. They may have been overlooked in
collecting in limestone, however, as they are fairly
numerous in the Hidden Valley Dolomite. This family
is well represented in the Silurian of Gotland and
elsewhere in Europe where the genera include Phau-
lactis, Cyathactis, Pycnactis, and Ryderophyllum.

The Lykophyllidae are medium and large solitary
Rugosa with many columns of small to medium, rather
steeply inclined dissepiments and a fairly wide tabu-
larium made up of closely spaced, uneven, mostly in-
complete tabulae and flat tabellae. Greatly thickened
septa of early growth stages persist ontogenetically to
at least early adult growth. A fossula is not generally
present in mature transverse sections.

In the Great Basin Silurian, the Lykophyllidae are
represented by abundant Ryderophyllum in Great
Basin Silurian coral zone B of the Hidden Valley
Dolomite (Merriam, 1973a) but are unknown in higher
horizons of the dolomite facies and have not been iden-
tified from limestone facies of the better known sec-
tions. A lykophyllid resembling Ryderophyllum from
an undetermined stratigraphic horizon in the Tusca-
rora Mountains is figured here (pl. 12, figs. 34—36).

 

37

FOSSILS ASSOCIATED WITH RUGOSE CORALS
IN GREAT BASIN SILURIAN LIMESTONES

Tabulate corals, crinoids, brachiopods, and dasycla—
dacean algae are common members as well as a Her-
cynella-like mollusk (pl. 10, fig. 20) of Great Basin
Silurian coral communities. In general, the most
abundant fossil remains of the limestone coralline
facies are favositids, including entire massive heads of
Favosites (pl. 10, figs. 9—13) and digitate forms (pl. 10,
fig. 8). With these branching corals are the more slen-
der ramose genera Cladopora (pl. 10, figs. 5—7) and
Coenites. Halysites is rather uncommon and seems to
be absent from the higher Silurian beds. Crinoids are
represented by large volumes of crinoidal debris filling
interstices and making crinoidal limestone, but no ar-
ticulated or partial crinoid crowns were collected.

Limestone beds that contain silicified fossils yield
abundant well-preserved brachiopods during extrac-
tion of the Coral material by the acid technique. Among
such occurrences are the Great Basin Silurian zone D
coralline beds in unit 3 of the Roberts Mountains For-
mation type section, the upper coral-rich beds of Great
Basin Silurian coral zone E at Coal Canyon, Simpson
Park Mountains, and the lower beds of this formation
at Bootstrap Hill, Tuscarora Mountains, Nev.

A few of the more distinctive brachiopods occurring
with Silurian corals are illustrated herein. The follow-
ing brachiopods occur in unit 3 of the type section
Roberts Mountains Formation:

Dicoelosia sp. r (pl. 11, figs. 18—22)
Gypidula sp. r (pl. 11, figs. 25, 26)
Homoeospira sp. r (pl. 11, figs. 15—17)
Kozlowskiellina sp. f (pl. 11, figs. 9—12)

Silicified brachiopods from Great Basin Silurian
coral zone E on the east side of Coal Canyon are:

Kozlowskiellina sp. f (pl. 11, figs. 13, 14)
Plectatrypa? sp. 0 (pl. 11, figs. 23, 24)

From the Roberts Mountains Formation of the
Bootstrap Hill area, Tuscarora Mountains, unusually
well preserved silicified brachiopods were collected by
R. J. Roberts from a large talus slab at the base of the
slope where the lowest beds of the formation are partly
exposed. Other rocks in the same collection contained
Cyathophylloides sp. f, an indicator of coral zone A.
The following associated brachiopods are figured in
this report:

Conchidium sp. b (pl. 12, figs. 18—22)
Fardenia sp. b (pl. 12, figs. 8—15)

Coelospira sp. b (pl. 12, figs. 1—7)
Kozlowskiellina sp. b (pl. 12, figs. 16, 17, 23)

Kozlowskiellina sp. f, which occurs in both Great
Basin Silurian coral zones D and E, bears a rather
close resemblance to Plicocyrtina sinuplicata Havlicek
as figured by Lenz (1972, pl. 1, figs. 1—20). According to

38

Lenz, the Canadian species is of Early Devonian (late
Siegenian) age.

In the type section of the Roberts Mountains Forma-
tion, the brachiopod Conchidium is most abundant and
diverse near the top of lithologic unit 2 and below
Great Basin Silurian coral zone C. These pentameroid
brachiopod faunas have not been studied in detail. The
form resembling Conchidium miinsteri Kiaer is illus—
trated (pl. 12, figs. 24—26).

DASYCIADACEAN ALGAE AS INDICATORS
OF THE SILURIAN

The family Dasycladaceae of green calcareous algae
has a very long geologic range, through the Paleozoic
to the present day. One of its subgroups, the Verticil-
loporaea (Rezak, 1959), throve in Great Basin Silurian
seas, occupying environments favorable for the corals.
In the Great Basin province, the family is well repre-
sented by the genus Verticillopora Rezak (pl. 10, figs.
1—4; pl. 11, figs. 1—8), some of whose individuals at-
tained a relatively large size for the family. Verticil-
lopora is a fairly reliable Great Basin Silurian indi-
cator, as its remains have not yet been recognized in
Ordovician strata and it is rarely found in rocks of
early Devonian age. Its usefulness as a Silurian fossil
was not recognized until recently; the cylindrical and
conical thalli were generally ignored; collectors re-
garded them as fragmentary sponges or crinoid colum-
nar segments, both of which they resemble in gross
surficial features. Moreover, the dasycladaceans not
uncommonly occur in crinoidal limestone.

The classification of living and fossil dasycladacean
algae has been reviewed by Pia (1926, p. 105). In 1959,
Rezak described Great Basin Silurian algal forms col-
lected by US. Geological Survey mapping parties.
Most of these specimens were assigned to the new
genus Verticillopora Rezak. This genus is usually pre-
served by silicification. Its thallus commonly has the
externally jointed appearance of a large crinoid stem
with numerous rather uniformly perforated columnar
segments. Internally the structure differs markedly
from that of a crinoid column by having a wide, com-
monly five-sided or polygonal central chamber that
housed the stipe (Rezak, 1959, p. 119), surrounded by
cycles of small radiating tubes or canals that contained
the lateral rays. Externally each segment reveals the
small-ray canal pores (pl. 11, figs. 3, 6). Some individ-
uals (pl. 10, figs. 1—3) have long, stout, tubular rootlike
processes.

Verticillopora ranges upward from Great Basin Silu-
rian coral zone B through coral zone E and into the
Early Devonian. Unlike some rugose coral genera,
Verticillopora is present in both limestone and dolo-
mite facies of the Great Basin Silurian. This algal

 

ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

group seems to have attained its peak of development
in limestone facies of Great Basin Silurian coral zone
D. In the Vaughn Gulch Limestone of the Inyo Moun-
tains, for example, the middle part of the formation
below Great Basin Silurian coral zone E is heavily
populated by Verticillopora annulata Rezak. The Ver-
ticillopora beds have yielded much of the best study
material of this interesting calcareous algal family.

(IONODON’I'S OF THE ROBERTS MOUNTAINS FORMATION
By _]0HN W. HUDDLE

Conodonts are abundant in much of the Roberts
Mountains Formation. The presence of these microfos-
sils where no megafossils occur makes their use espe-
cially important for stratigraphic studies and geologic
mapping. Many conodont identifications were made for
geologists mapping in the Carlin gold mine vicinity
and other areas of the central Great Basin where the
Silurian and Devonian strata are intensely deformed
and would otherwise remain undated paleontologi-
cally. In order to correlate the isolated conodont occur-
rences with more continuous sections of the Roberts
Mountains Formation, during this investigation cono-
dont-bearing material was collected from beds yielding
distinctive rugose corals and other megafossils of age
significance. Conodont control sections have been
measured in areas that have been mapped geologically
in the Toquima, Monitor, and Simpson Park Ranges.
Much more bed-by-bed conodont collecting remains to
be done in these more continuous Silurian and Devo-
nian control sections. An important conodont study of
the type section of the Roberts Mountains Formation
and nearby locations in the Roberts Mountains is that
of Klapper and Murphy (1974); this study serves as a
reference for comparison of other collected strati-
graphic intervals in the central Great Basin.

A chart (table 2) of Roberts Mountains Formation
conodont assemblages collected from the Toquima
Range and localities between the Toquima Range and
the Tuscarora Mountains lists conodont stratigraphic
ranges. In addition, conodonts from the overlying Rab-
bit Hill Limestone are included.

The largest assemblages of conodonts listed here
come from the upper part of the Roberts Mountains For-
mation at Coal Canyon, Simpson Park Mountains, on
both the west and east sides of the Coal Canyon fault,
and in the August Canyon sequence at Gatecliff in the
Toquima Range. Here the name Bastille Limestone
Member of the Masket shale of Kay and Crawford
(1964) is used for strata correlative with part of the
Roberts Mountains Formation.

Conodont form taxa are used in this report. Some
multielement taxa are recognized, but until the mul-

LOCALITY REGISTER OF MAJOR FOSSIL LOCALITIES

tielement taxonomy is generally used, the form taxa
will serve for stratigraphic studies.

Comments on some of the collections of specific stra-
tigraphic interest are: Locality KV—70—19 (8827—SD)
(table 2, No. 6), from the Carlinastraea beds, Coal Can-

yon in the Simpson Park Mountains.

The presence of Spathognathodus remscheidensis indicates that
this collection is Early Devonian according to conodont zonation.
The faunal list gives form taxa because it is simpler to use for
stratigraphic purposes until the multielement taxonomy is more
completely established. Spathognathodus inclinatus and several
of the bar-type conodonts listed above (table 2) are part of a mul-
tielement taxon called ‘Apparat-H’ by Walliser (1964), Hin-
deodella excavata by Jeppsson (1969), and Ozarkodina inclinata
by Walliser (1972).

Locality KV—70—24 (8829—SD) (table 2, No. 7), Car-
linastraea beds, Coal Canyon, Simpson Park Mountains.

Spathognathodus remscheidensis indicates an Early Devonian
age for this collection and Rotundacodina elegans has been
reported only from Early Devonian rocks. The new species of
Spathognathodus is similar to S. remscheidensis but has aborted
and small denticles anterior to the basal cavity.

Two conodont assemblages from the upper part of
the Roberts Mountains Formation on the east side of
the Coal Canyon fault in the Pyramid Hill block (table
2, Nos. 8 and 9) are from the interval of Great Basin
Silurian coral zone E (collection 8216—SD, table 2,
No. 8, made by T. E. Mullens):

The list includes only form taxa, and several ofthe bar elements
belonged to multielement species. The age of the fauna is Early
Devonian according to the known conodont ranges. This age is
indicated by Spathognathodus remscheidensis, Spathognathodus
transitans, and the form ofSpathognathodus inclinatus, which is
the one common in Lower Devonian rocks. The Icriodus is only a
small fragment and is not specifically identifiable, but it also
suggests a Devonian age. The Scolopodus devonicus is known only
from Devonian collections. Many of the other conodonts range
from Silurian to Devonian. Although there are few Late Silurian
faunas described now (1973), all the evidence available indicates a
Devonian age for this collection.

Collection 8828—SD (table 2, No. 9):

The two species ofRotundacodina were described by Carls and
Gandl (1969) from the Lower Devonian of northeastern Spain.
These species and Spathognathodus remscheidensis indicate an
Early Devonian age for this collection. The new species of
Spathognathodus, S. sp., differs from S. remscheidensis by having
aborted anterior denticles instead oftall anterior denticles as in S.
remscheidensis. Spathognathodus sp. occurs with Spathog-
nathodus boucoti Klapper, an Early Devonian species, in a collec-
tion made by T. E. Mullens near Carlin, Nev. (USGS 100. 8447—
SD). This occurrence supports my opinion that S. n. sp. cf.
Spathognathodus remscheidensis is an Early Devonian species.
Klapper reports (oral commun., March 1971) the occurrence of
what is probably the same species with aborted anterior denticles
in the Gedinnian Windmill Limestone of Johnson and Murphy
(1969) at a stratigraphic horizon of 1,617 feet (493 m) in the west
Coal Canyon section in the Simpson Park Mountains and on Pete
Hanson Creek in the Roberts Mountains. It is unfortunate that
species of Icriodus are not present in these collections of Silurian
Coral Zone E to confirm the Early Devonian age of the Zone in
terms of conodont chronology. Klapper and Murphy (1974), re-
ported I. woschmidti from Birch Creek in the Roberts Mountains

 

39

in the upper part of Roberts Mountains Formation.

Bed-by-bed collecting will be required to firmly es-
tablish conodont zonal distribution in these western
Silurian and Devonian strata. Lowermost Devonian on
the conodont scale conforms closely to that of the grap-
tolite scale, placing the base of the Devonian System
below or within Great Basin Silurian coral zone E. Al-
though only a few conodonts have been identified from
the Rabbit Hill Limestone, most of these are distinc-
tive Early Devonian forms not recognized in the
Roberts Mountains Formation.

LOCALITY REGISTER OF MAJOR FOSSIL
LOCALITIES IN THE ROBERTS MOUNTAINS
FORMATION AND CORRELATIVE STRATA

Roberts Mountains, Nev.

M1100.—Roberts Creek Mountain quadrangle, Nevada. Northwest
side of Roberts Creek Mountain on measured section 550 m N. 79°
W. of summit 9219 at altitude 8,680 feet. Upper part of Roberts
Mountains Formation, unit 3.

M1102.—Roberts Creek Mountain quadrangle, Nevada. Northwest
side of Roberts Creek Mountain. Lower beds of Roberts Mountains
Formation unit 3 with Prohexagonaria. In measured reference
section.

Northern Simpson Park Mountains, Nev. ,

M1032.——Horse Creek Valley quadrangle, Nevada. East side of Coal
Canyon in NW% sec. 21, T. 25 N., R. 49 E. Rabbit Hill Limestone.
Collected by R. J. Roberts, 1954.

M1075.—Horse Creek Valley quadrangle, Nevada. Near mouth of
Coal Canyon, east side along top of ridge of summit 6909. Rabbit
Hill Limestone, Lower Devonian.

M1076.—Horse Creek Valley quadrangle, Nevada. Near mouth of
Coal Canyon, east side. Mostly float below top of ridge of summit
6909 and downslope to west. Rabbit Hill Limestone, Lower Devo-
nian.

M1105.—Horse Creek Valley quadrangle, Nevada. Coal Canyon;
float at canyon bottom 0.6 km south of mouth of Coal Canyon.
Material probably from upper part of the section or upper coral-
rich limestone breccia below Rabbit Hill Limestone.

M1105a.—Horse Creek Valley quadrangle, Nevada. Coal Canyon;
float at canyon bottom 0.6 km south of mouth of Coal Canyon.
Material probably from upper part of the section or upper coral-
rich limestone breccia below Rabbit Hill Limestone.

M1106.—Horse Creek Valley quadrangle, Nevada. Coal Canyon
near mouth in SE14 sec. 17, T. 25 N., R. 49 E.; east side ofcanyon at
altitude about 6,300 feet. Coral-rich limestone depositional breccia
in upper part of the Roberts Mountains Formation and below Rab-
bit Hill Limestone.

M1107.—Horse Creek Valley quadrangle, Nevada. About 0.6 km
south of mouth of Coal Canyon on east side of canyon and about
60 m above canyon bottom. Coral-rich limestone and depositional
limestone breccia. Roberts Mountains Formation.

M1108.—Horse Creek Valley quadrangle, Nevada. Coal Canyon,
near mouth. Float collections below coral-bearing depositional
breccia on east side of canyon below locality M1107. Roberts
Mountains Formation.

M1110.—Horse Creek Valley quadrangle, Nevada. Coal Canyon,
near mouth. Coral-rich breccia limestone near top of Roberts
Mountains section on east side of canyon. Collection made by A. J.
Boucot, 1964.

M1310.—Horse Creek Valley quadrangle, Nevada. SEM; sec. 17, T.
25 N., R. 49 E. West side of summit 6909 (Pyramid Hill) near top.

40 ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

TABLE 2.—Occurrence chart of conodont species collected from Silurian and Lower Devonian formations in central Nevada

[Conodont species listed are form taxa. Identification by J. W. Huddle. Multielement apparatus reconstructions in the sense of Jeppson (1969) and Klapper and Philip (19711 have not
been attempted]

 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Acodina sp ______________________________________________ HH HH HH __ >< HH HH __ HH HH H H HH __ H
Belodella devonica (Stauffer) ______________________________ H __ HH __ __ HH H X H H H X X __ H
Belodella resima (Philip) ________________________________ H __ H __ __ H H H H X H HH H H H
Belodella sp ____________________________________________ H X H H __ X H X X H X _H H H __
Eantiognathus lipperti Bischoff ____________________________ X H H H H H H H H H H HH H H H
Hibbardella sp __________________________________________ X H H H H H H H HH __ H H H H HH
Hindeodella sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, X x H x __ x X X x H x X H H H
I criodus latericrescens Branson and Mehl (subspecies not de-

termined) ____________________________________________ __ H H __ H __ H H H H __ H H H X
Icriodus latericrescens huddlei Klapper and Ziegler ________ H __ __ H X __ H H H H HH H H H- HH
Icriodus latericrescens subspecies B Klapper1 ______________ A _ __ H X __ H __ H H H H H H H
Icriodus latericrescens aff. I . latericrescens subspecies B Klap-

per ____________________________________________________ H X __ H __ __ H __ H X H H H H H
Icriodus sp ______________________________________________ H H H __ H H __ >< __ X __ H H X X
Ligonodina sp __________________________________________ __ H HH __ H HH __ HH X H HH __ H H HH
Lonchodina walliseri Ziegler ______________________________ __ H HH __ H H __ X H HH H H H H H
Lonchodina sp __________________________________________ __ __ HH H __ H H H X __ HH H HH H H
Neoprioniodus excavatus (Branson and Mehl) ______________ H __ >< HH __ X H X X H X x X _H H
Neoprioniodus multiformis? Walliser ______________________ HH H __ H __ __ HH >< __ H H H H H H
Oneotodus? beckmanni Bischoff HHHHHHHHHHHHHHHHHHHHHHHHHHH HH >< __ __ H H __ H H H H H H HH H
Ozarkodina denckmanni Ziegler __________________________ HH >< __ __ H X x X X H __ HH H H __
Ozarkodina gaertneri Walliser ____________________________ HH H H __ HH H H H H HH H H X H HH
Ozarkodina media Walliser ______________________________ __ _H x H H x __ X H HH X H H H H
Ozarkodina aff. 0. media Walliser ________________________ H H H HH __ H HH __ _H __ H X _H H H
Ozarkodina typica Branson and Mehl HHHHHHHHHHHHHHHHHHHHHH __ __ HH H _H HH H x HH __ HH H H H H
Ozarkodina ziegleri Walliser HHHHHHHHHHHHHHHHHHHHHHHHHHHHHH H H H HH __ H HH __ HH H H X HH H H
Ozarkodina aff. O. Ziegleri Walliser ______________________ HH H __ x H __ __ HH __ H H H __ HH H
Ozarkodina sp __________________________________________ >< __ H __ H H __ HH __ __ H H H X H
Paltodus afT. P. migratus Rexroad ________________________ H H _H HH __ _H HH __ HH __ HH X X H HH
Paltodus sp ____________________________________________ HH H __ HH H __ x X __ HH __ X H HH __
Panderodus sp __________________________________________ __ H X X H __ __ X X HH __ X X HH X
Pelekysgnathus furnishi Klapper HHHHHHHHHHHHHHHHHHHHHHHHHH H H H HH H H HH H HH H H H HH H X
Pelekysgnathus sp ________________________________________ HH H __ HH H __ __ HH __ HH H HH X X H
Plectospathodus extensus Rhodes HHHHHHHHHHHHHHHHHHHHHHHHHH HH H X H HH __ H X __ HH X X H HH H
Plectospathodus aff. P. alternatus Walliser ________________ H __ __ HH H H HH X H H HH __ H H H
Plectospathodus sp HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH >< __ H H __ X H H X H H H H H H
Polygnathus foveolatus Philip and Jackson ________________ H __ H H __ H H __ HH H H H __ H X
Prioniodina sp HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH X H H HH HH X HH H HH H HH -H H X __
Rotundacodina elegans Carls and Gandl __________________ HH H __ HH H __ x H X HH H HH H HH H
Rotundacodina noguerensis Carls and Gandl ______________ H H H H HH __ H HH >< HH H HH H- H HH
Scolopodus deuonicus Bischoff and Sannemann HHHHHHHHHHHH x H HH __ H H __ >< __ H H H H H HH
Spathognathodus inclinatus inclinatus Rhodes HHHHHHHHHHHH X H x x __ >< __ X H H HH H H H HH
Spathognathodus primus (Branson and Mehl)1 ____________ __ __ __ H __ __ HH H H __ H X H A H
Spathognathodus eosteinhornensis Walliser1 HHHHHHHHHHHHHH HH H H __ HH H H HH H HH H A H HH H
Spathognathodus remscheidensis Ziegler1 HHHHHHHHHHHHHHHHHH __ H x H _ x X A A H H H H H HH
Spathognathodus n. sp., of. S. steinhornensis remscheidensis HH >< __ _H H H X X X H H H H H H

Ziegler HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH HH H __ __ HH __ H X __ H __ H A HH H
Spathognathodus transitans Bischoff and Sannemanl ______ H __ __ H H HH __ x H __ H H __ H H
Spathognathodus cf. S. transitans Bischot’t' HHHHHHHHHHHHHHHH >< __ __ HH __ __ HH H __ H H H H HH H
Spathognathodus sp HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH HH __ __ x H __ __ HH H HH H H __ H H
Synprioniodina sp HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH H H x H H HH H __ HH __ HH H H H _H
Synprioniodina sp ________________________________________ __ H HH H __ H x X x H __ H __ HH H
Trichonodella blanda (Stauffer) __________________________ __ __ H HH __ __ __ H X HH H _H H _H H
Trichonodella blanda? (Stauf‘fer) HHHHHHHHHHHHHHHHHHHHHHHHHH H H __ __ H H X __ HH H HH H H H HH
Trichonodella inconstans Walliser ________________________ >< __ H H __ HH H __ H __ H H _H X H
Trichonodella sp ________________________________________ __ H __ __ H X x HH X H __ H H H HH

 

Approximate stratigraphic position

 

Geographic locality: Formation: of fossil collection:
1. 9165—SD HHHHHHHHH Toquima Range, Mill Canyon in Bastille Limestone Member of Mas- 31 m above top of chert member of
August Canyon structural se- ket Shale of Kay and Crawford Gatecliff Fm. of Kay (1960).
quence. (1964).
2. 9166—SD _______________________ do HHHHHHHHHHHHHHHH Upper member of Masket Shale of 91 m above top of chert member of
Kay and Crawford (1964). Gatecliff Fm. of Kay (1960).
3. 8214—SD HHHHHHHHH Mténitor Range, Copenhagen Roberts Mountains Formation H... 119 In above base of formation.
anyon.
4. 8304—SD HHHHHHHHHHHHHHHHHHHHHHH do ______________________________ do ________________ 187 m above base of formation.
5. 9167—SD HHHHHHHHHHHHHHHHHHHHHHH do ________________ Rabbit Hill Limestone HHHHHHHHHHHH Upper 31 m of formation at type
section.
6. 8827—SD HHHHHHHHH Northern Simpson Park Mountains, Thick-bedded upper part of Roberts Carlinastraea beds; unmeasured lo-
Coal Canyon. Mountains Formation (mapped cality about 460 In above base of
as Windmill Limestone by J ohn- formation of west side of Coal

son (1965) and Johnson and Mur- Canyon.2
phy (1969).

LOCALITY REGISTER OF MAJOR FOSSIL LOCALITIES

41

TABLE 2.—OCczlrrence chart of conodont species collected from Silurian and Lower Devonian formations in central Nevada—Continued

 

Approximate stratigraphic position

 

Geographic locality: Formation: of fossil collection:

7. 8829—SD _______________________ do ______________________________ do ________________ Carlinastraea beds; unmeasured lo-
cality near 8827—SD.

8. 8216—SD _______________________ do ______________________________ do ________________ Unmeasured locality; east side Coal
Canyon about 520 m above base
of formation.2

9. 8828—SD _______________________ do ______________________________ do ________________ Unmeasured locality; east side Coal
Canyon about 550 m above base
of formation.2

10. 9168—SD ,,,,,,,,,,,,,,,,,,,,,,, do ________________ Rabbit Hill Limestone ____________ Unmeasured locality; east side Coal
Canyon about 70 m above base of
formation.2

11. 8228—SD _________ Tuscarora Mountains, Bootstrap Roberts Mountains Formation ,1“ Lower 15 m of exposed section.

Hill.

12. 8219—SD _______________________ do ______________________________ do ________________ 37 m above base of exposed section.

13. 8219A—SD _____________________ do ______________________________ do ________________ 119 m above base of exposed section.

14. 8215—SD _______________________ do ________________ Roberts Mountains Formation ____ 244 m above base of exposed section.

(thick—bedded facies).
15. 8826—SD _________ Carlin area, Maggie Creek ________ Rabbit Hill Limestone ____________ Unmeasured locality east side of

Maggie Creek. ‘

 

‘Some occurrences of this taxon are anomalous with respect to its stratigraphic range as previously reported from central Nevada. (Klapper, 1968; Klapper and others, 1971: Klapper
and Murphy, 1975), the Canadian Yukon (Klapper, 1969: Fahraeus 1971), and Europe (Ziegler, 1971), and relative to monograptids of the Monograptus umformzs and Monograptus
lzercynicus groups. In order to accommodate this discrepancy, the anomalous stratigraphic occurrence of the taxon is shown as a A.

2The cited stratigraphic footage above base of the formation is estimated.

Upper 60 m of Rabbit Hill Limestone on this slope platy limestone
with abundant trilobites.

M131 7.—Horse Creek Valley quadrangle, Nevada. West side of Coal
Canyon in sec. 20, T. 25 N., R. 49 E. near middle of north bound-
ary, altitude about 6,600 feet. About 503 m stratigraphically above
base of the Roberts Mountains Formation. Colonial rugose corals
in 'place.

M1318.—H0rse Creek Valley quadrangle, Nevada. West side of Coal
Canyon, about 152 m west of canyon bottom at altitude 6,400 feet.
Float material oflarge Australophyllum, probably from Coal Can-
yon fault zone in the Roberts Mountains Formation.

M1331.—H0rse Creek Valley quadrangle, Nevada. Coal Canyon.
SW%SW% sec. 16, T. 25 N., R. 49 E.; east side of summit 6909
(Pyramid Hill), altitude 6,840 feet just east of section line, 150 m
southeast of flag station 6909. Rabbit Hill Limestone.

M1332.—H0rse Creek Valley quadrangle, Nevada. Coal Canyon
area, top of Pyramid Hill (summit 6909), northwest of M1331, at
flag station. Rabbit Hill Limestone.

M1333.—H0rse Creek Valley quadrangle, Nevada. Coal Canyon
area. West side of Coal Canyon, NEIA; sec. 20 near section line,
305 m northwest of hill 6400 at altitude 6,560 feet. About same
zone as M1317. Dark-gray well-bedded limestone with abundant
Favosites and other corals including a pycnostylid. Brachiopods
present. Roberts Mountains Formation.

M1334.—H0rse Creek Valley quadrangle, Nevada. Coal Canyon
area. SE14 sec. 17, T. 25 N., R. 49 E. on west side of Coal Canyon
460 in northwest of hill 6400 at altitude 6,560 feet and 200 on north
of M1333, Roberts Mountains Formation. Dark-gray limestone
with corals and brachiopods.

M1379.—H0rse Creek Valley quadrangle, Nevada. West side of Coal
Canyon near its mouth, SE1/4 sec. 17, T. 25 N., R. 49 E.; 460 m N.
78° W. of summit of hill 6909, altitude 6,400 feet. East-dipping
limestone of Roberts Mountains Formation, fault sliver in Coal
Canyon shear zone. On crest of northeast-extending spur.

M1380.—Horse Creek Valley quadrangle, Nevada. Coal Canyon,
850 in south of canyon mouth; NE‘A sec. 20, T. 25 N., R. 49 E.;
2,200 feet S. 33° W. of summit of hill 6909 on east side near top
small knoll in canyon, altitude 6,400 feet. Upper beds of Roberts
Mountains Formation, Great Basin Silurian coral zone E.

M1381.-—-Horse Creek Valley quadrangle, Nevada. Coal Canyon east
side, 760 m south of canyon mouth, 520 m S. 40° W. of summit of

 

hill 6909, altitude 6,320 feet. Upper beds of Roberts Mountains
Formation.

M1383.—Horse Creek Valley quadrangle, Nevada. Coal Canyon,
west side sec. 17 near middle of south edge, T. 25 N., R. 49 E. At
crest northeast spur 670 m S. 79° W. of summit of hill 6909, al-
titude 6,580 feet. Roberts Mountains Formation.

M1384.—Horse Creek Valley quadrangle, Nevada. Coal Canyon
west side, NEM; sec. 20, T. 25 N., R. 49 E.; 760 m S. 53° W. of
summit 6909, altitude 6,520 feet. Roberts Mountains Formation.
Carlinastraea tuscaroraensis locality.

M1411.—H0rse Creek Valley quadrangle, Nevada. West side of Coal
Canyon 0.8 km south of canyon mouth at altitude 6,360 feet on
northwest side of small limestone knob, altitude 6,400 feet.
Roberts Mountains Formation with Verticillopora.

M1446.—Horse Creek Valley quadrangle, Nevada. Foothills on
north side of Simpson Park Mountains; 2.4 km north of Red Hill in
SEMiNEMi sec. 5, T. 25 N., R. 50 E. Low pediment exposures of
Roberts Mountains Formation.

M1448.——H0rse Creek Valley quadrangle, Nevada. East side of Pine
Hill, 150 m south of middle of north edge of sec. 20, T. 25 N., R. 49
E., near north-south midline of section; altitude 6,500 feet. Roberts
Mountains Formation. In coral beds with Carlinastraea.

M1449.—H0rse Creek Valley quadrangle, Nevada. Top of main
northeast spur of Pine Hill, 213 m north of south boundary of sec.
17, T. 25 N., R. 49 E., at north-south midline of section. Roberts
Mountains Formation. In coral beds with Carlinastraea.

M1450.—Horse Creek Valley quadrangle, Nevada. Coal Canyon,
east side about 335 m south of canyon mouth at altitude 6,300 feet.
Coral collection mostly float material. Great Basin Silurian coral
zone E. Roberts Mountains Formation.

M1451.—H0rse Creek Valley quadrangle, Nevada. Coal Canyon,
east side about 100 m south of canyon mouth at altitude 6,280 feet.
Coral collections mostly loose float material. Great Basin Silurian
coral zone E. Roberts Mountains Formation.

M1452.—Horse Creek Valley quadrangle, Nevada. Coal Canyon,
west side about 460 m south of canyon mouth, altitude 6,300 feet.
Within the Coal Canyon fault zone. Roberts Mountains Formation.

M1453.—H0rse Creek Valley quadrangle, Nevada. Coal Canyon in
NE% sec. 20, T. 25 N., R. 49 E., on top of small knoll 0.8 km south
of canyon mouth, altitude 6,400 feet. Great Basin Silurian coral
zone E. Roberts Mountains Formation.

42

M1454.—Horse Creek Valley quadrangle, Nevada. Coal Canyon
about 975 In south of canyon mouth, altitude 6,400 feet on top of
spur on which the Middle Devonian Woodpecker Limestone
Member of the Nevada Formation is apparently overridden by an
upper plate comprising parts of the Roberts Mountains Formation
and overlying Rabbit Hill Limestone.

M1455.—Horse Creek Valley quadrangle, Nevada. Coal Canyon
about 975 m south of canyon mouth, altitude 6,400 feet, on top of
spur about 60 in east of M1454. Mixed Devonian assemblage ap—
parently from both the Middle Devonian Woodpecker Limestone
Member of the Nevada Formation and the Lower Devonian Rabbit
Hill Limestone tectonically involved in the thrust.

M1456.—Horse Creek Valley quadrangle, Nevada. South middle
part of sec. 17, T. 25 N., R. 49 E., at crest of main northeast spur,
altitude 6,600 feet. In thick-bedded limestone with rugose corals.
Roberts Mountains Formation.

Cortez Mountains, Nev.

M1409.—Cortez quadrangle, Nevada. West base of Cortez Moun-
tains about 1.6 km southeast of the town of Cortez. NEl/4 sec. 17, T.
26 N., R. 48 E., 2.6 km N. 76° E. of BM 5748, altitude 6,400 feet.
Roberts Mountains Formation. Carlinastraea; probable float
material.

Sulphur Spring Range, Nev.

M1148.—Garden Valley quadrangle, Nevada. Southern part of Sul—
phur Spring Range. East side of range in northeast corner sec. 35,
T. 23 N., R. 52 E. Lone Mountain Dolomite with corals 0.8 km
north-northwest of BM 5867 on east-west spur, altitude 6,100 feet.

Southern Tuscarora Mountains, Nev.

M1120.—Tuscarora Mountains near north end of Eureka County,
Nev.; "Round Mountain,” bottom of hill at southwest end. Col—
lected by R. J. Roberts, June 1958. Roberts Mountains Formation
limestone.

M1313.—Bootstrap mine area, Nevada. Bootstrap Hill section.
Roberts Mountains Formation about 400 m stratigraphically
above base of section on top of knob. Carlinastraea bed.

M1314.—Bootstrap mine area. Bootstrap Hill stratigraphic section
200—250 In stratigraphically above base. Roberts Mountains For—
mation.

M1315.—Bootstrap mine area. Bootstrap Hill stratigraphic section
about 230 m stratigraphically above base. Roberts Mountains
Formation.

M1412.—Tuscarora Mountains, Nev. Advance quadrangle sheet
USGS Tuscarora 3SW (7—7—68); Elko County, Nev., near north
edge of Eureka County. Bootstrap Hill area southwest of Bootstrap
Hill. Just north of Eureka County-Elko County line at bottom of
ridge about 300 m east of Dunphy—Tuscarora road and about 1,830
m S. 17° W. of top of Bootstrap Hill. Probably a large float boulder;
contains silicified brachiopods in abundance.

M1413.—Tuscarora Mountains, Nev. Northeast Eureka County.
Northeast of the Lynn window of R. J. Roberts. Collected by R. J.
Roberts, 1958. Corals. Possibly in Jack’s Creek drainage northeast
of Big Six mine. Roberts Mountains Formation.

Toquima Range, Nev.

M1103.—Dianas Punch Bowl quadrangle, Nevada. Ikes Canyon.
About 1.6 km up canyon from mouth on north side and about
100 m in altitude above creek bottom, altitude 7,900 feet. South-
east of Ikes cabin. Roberts Mountains Formation or Masket Shale
of Kay and Crawford (1964). Coral-rich limestone with Verticil-
lopora.

M1114.—Dianas Punch Bowl quadrangle, Nevada. Ikes Canyon
area; 200 m northwest of summit 8474 (Copper Mountain), al-
titude 8,300 feet. In McMonnigal Limestone. Coral fauna with
Toquimaphyllum. Great Basin Silurian coral zone E.

M1147.—Northeast corner of Wildcat Peak quadrangle. SW%SW%
sec. 16, T. 16 N., R. 46 E., on top of divide west of Henry Meyer

 

ROBERTS MOUNTAINS FORMATION, REGIONAL STUDY

Canyon, altitude 6,960 feet. Roberts Mountains Formation in beds
with a fauna similar to that in the Rabbit Hill Limestone sur—
rounded by graptolitic beds of Silurian age.

M1393 .—Dianas Punch Bowl quadrangle, Nevada. South side of Ikes
Canyon, a little less than 1.7 km northwest of canyon mouth.
McMonnigal Limestone.

M1394.—Southeast corner of Wildcat Peak quadrangle. On north
side of Mill Canyon 1,525 in west of east border of quadrangle on
top of spur, altitude 8,560 feet and 730 m north of south boundary
ofquadrangle. Bastille Limestone Member of Masket Shale of Kay
and Crawford (1964).

M1395.—Southeast corner of Wildcat Peak quadrangle. On north
side of Mill canyon, altitude 8,000 feet and 2,400 m west of east
border of quadrangle. Bastille Limestone Member of Masket Shale
of Kay and Crawford (1964).

M1396.——Southeast corner of Wildcat Peak quadrangle, 1,220 m
west of east border of quadrangle and 1,130 m north of south
boundary of quadrangle; altitude 8,500 feet. Bastille Limestone
Member of Masket Shale of Kay and Crawford (1964).

M1397.—Wildcat Peak quadrangle, Nevada. South side of Stone-
berger Basin, 2.4 km southeast of top of Whiterock Mountain at
altitude 9,100 feet, just east of letter "n” in word “Basin” of
"Stoneberger Basin” (Wildcat Peak quadrangle). Tor Limestone.

Northern Inyo Mountains, Calif.

M1090.—~Independence quadrangle, California. East of Kearsarge at
mouth of Mazourka Canyon. In NElfli sec. 8, T. 13 S., R. 36 E.
Within 6 m of top Vaughn Gulch Limestone. Poorly preserved
fossils of probable Early Devonian age.

M1091.—Independence quadrangle, California. At mouth of
Mazourka Canyon. Near east line of sec. 8, T. 13 S., R. 36 E. at
middle of NE‘A, 366 In north of Vaughn Gulch creek bottom, al-
titude 4,840 feet. About 46 m stratigraphically above chert unit at
base of Vaughn Gulch Limestone.

M1092.~Independence quadrangle, California. Same measured sec-
tion as M1091, west of east section line of sec. 8 in NE%, altitude
4,880 feet. Middle part of Vaughn Gulch Limestone about 305 m
stratigraphically above the Eureka Quartzite equivalent.

M1093.—Independence quadrangle, California. East of Kearsarge at
mouth of Mazourka Canyon. In NE1/4 sec. 8, T. 13 S., R. 36 E. Base
of upper unit of Vaughn Gulch Limestone about 412 m strati—
graphically above Eureka Quartzite equivalent and 137 m below
top of Vaughn Gulch Limestone.

M1115.—Independence quadrangle, California. East of Kearsarge at
mouth of Mazourka Canyon. Measured section of Vaughn Gulch
Limestone about 34 In stratigraphically below horizon of M1093.
Rugose coral bed. _ ..

M1116.—Independence quadrangle, California. At mouth of
Mazourka Canyon in measured section in which are localities
M1092 and M1093. Coral bed about 9—15 m stratigraphically
below M1093, near top middle unit of Vaughn Gulch Limestone.

M1128.—Independence quadrangle, California. East of Kearsarge at
mouth of Mazourka Canyon. In measured section about 52 m
stratigraphically below M1093 in higher middle part of the
Vaughn Gulch Limestone. Beds with Verticillopora.

M1385.—Independence quadrangle, California. Sec. 8, T. 13 S.,
R. 36 E. Vaughn Gulch Limestone, Silurian. Probably same zone
as locality M1128. Verticillopora. Collected by Craig D.
Ross, 1961.

M1410.—Independence quadrangle, California. Mazourka Canyon
east of Kearsarge in measured section. At top of middle unit of
Vaughn Gulch Limestone and about 15 m stratigraphically below
locality M1093.

Gotland, Sweden

M1382.—Gotland, Sweden. Hemse Group. Stop 40 of Internat. Geol.

Cong. guidebook, 1960. Boardman collection, Sept. 10, 1960.

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1933, On Xylodes rugosus sp. nov., a Niagaran coral: Am.

Jour. Sci., ser. 5, v. 26, no. 155, p. 512—522, 1 p1.

1945, Upper Devonian corals of the Mackenzie River region,
Canada: Geol. Soc. America Spec. Paper 59, 126 p., 35 pls.
Stauffer, C. R., 1930, The Devonian of California: California Univ.

Pubs, Dept. Geology, v. 19, no. 4, p. 81—118, 5 pls.

Steidtmann, Edward, 1911, The evolution of limestone and dolomite,
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1917, Origin of dolomite as disclosed by stains and other
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Stevens, C. H., and Ridley, A. P., 1974, Middle Paleozoic off-shelf
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Stewart, J. H. and McKee, E. H., 1968, Geologic map of the Mount
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Stewart, J. H., and Palmer, A. R., 1967, Callaghan window—a newly
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45

 

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Page

A
Acinaphyllum , ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27
Acknowledgments ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2
Acodina sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40
Acrospirifer lzobehana fauna ,,,,,,,,,,,,,,,,,, 3

  

acus, Monograptus , HH , ,
Al Rose Canyon ,,,,,,,,,,,,,,,,,,,,,,,,,,, , H 28
Alaska, southeastern ,,,,,,,,,
alaskense, Conchidium ,,,,,,,
alaskensis, Conchidium H .

  
    

 

Algae, calcareous , HH. ,_ 2,4,5, 26, 29

dasycladacean ,,,,,,, 4, 5, 10, 15, 25, 26, 27, 29
alternatus, Plectospathodus H , ._H . ,HH ,HH .H, 40
Alveolites spH ,,,,,,,,,,,,,,,,,,,,,,,,, 13, 15, 17
Amplexoides ,,,,,,,,,,,,,,,,,,,,,,,

   

Amplexus HHHHHH. ,HHHH,
angustidens, Monograptus H, ,H ,

Retiolites geinitzianus H, , _ ,,,,,,, _ 19
annulata, Verticillopora ,,,,,,,,,,,, 5, 10, 14, 15, 22,
26, 27; pls.10, 11

Antelope Peak ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 7

  
 

Antelope Valley , ,H H
Antelope Valley Limestone H
Antilles. Netherlands , ,

 

Arachnophyllum ,,,,,,,,,,,,,,,
kayi , ,,,,,,,,,
Athyris ,H ,,,,,,,,,,,,,,,,,,,, , ,,,,,,,,,,,,,, ,
Atrypa ,,,,,,,,,,,,,,,,,,, , ,,,,,,,,,,,,,,,,,,,, 27
Sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, , 5, 10, 15, 17
August Canyon sequence _ ,,,,,,,,,,,,,,,,, 23, 24
August Canyon thrust sequence ,,,,,,,,,,,,,, 19,40
Aulacophyllum , ,,,,, , ,,,,,,,,,,,,,,,,,,,,,,,,, 27

AuloporaHHH. ,
Australia HHH _

     

Australophyllum ,,,,,,,,,,,,,,,,,,,,,,,,, 15, 29, 34
landerensis ,,,,,,,,, HHHHH.HH 27, 34, 35
stevensi ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 28
(A ustralophylluml sp. c H, ,,,,,,,,,,,,, 34,- pl, 8

sp, v ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 35; pl, 8
(Toquimapliyllum) ,,,,,,,,,,,,,,,,,,, 29, 34, 35

5,14,15,17.22,23,
27, 34,35, pl. 6

johnsam H, ,HH. ,__.,,

 

sp. v ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27, 34, 35
(Australophyllum) Sp. c, Australophyllum HH 34,- pl. 8
sp. v, Australophyllum ,,,,,,,,,,,,,,,,,, 35; pl, 8

B
Badger Flat ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 28
Bare Mountain H 7, 19

Roberts Mountains Formation ,,,,,,,,,,,,,,,, 20
Barrandella sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5, 15
Barrel Spring ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 28
Bastille Limestone Member ,,,,,,,,,,,,,,,,, 23, 40
Bathurst, R, G. C., cited ,,,,,,,,,,,,,,,,,,,,,,,,,, 6
Beacon Peak Dolomite Member,

Nevada Formation __H, ,,,,,,,,,,,,,,,,,, 3, 10
beckmanni, Oneotodus ,,,,,,,,,,,,,,,,,,,,,,,,, , 40
Belodella devonica ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40

resima ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40

sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40
Berry, W. B. N., cited ,,,,,,,,,,,,,, 2, 11, 13, 19, 28
berthiaumi, Stylopleura ,,,,,,,,,,,, 5, 10, 13, 15, 20,

31, 32,‘ pls. 1, 2

 

INDEX

[Italic page numbers indicate major references]

 

 

 

 

 

 

 

 

 

 

 

Page

Big Six Mine ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 16, 34

Bighorn Dolomite, Ordovician ,,,,,,,,,,,,,,,,,,,,, 7

Billingsastraea spi T ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 25

Bioherms, scarcity ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4

Birch Creek 7

birchensis, Monograptus ,,,,,,,,,,,,,,,,,,,,,,,,,, 19

bohemicus, Monograptus ,,,,,,,,,,,,,,,,,,,,,,,,, 13

Boone Creek area ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 24

Bootstrap Hill, Tuscarora Mountains ,,,,,,, 2, 14, 16,

30, 31,32, 33, 34, 41

Bootstrap Hill section, age ,,,,,,,,,,,,,,,,,,,,,, 17
lowest coral-brachiopod zone ,,,,,,,,,,,,,,,,,,, 16
middle coral-brachiopod zone ,,,,,,,,,,,,,,,, 1 7
physical stratigraphy ,,,,,,,,,,,,,,,,,,,,,,,, 16
stratigraphic paleontolong. ,,,,,,,,,,,,,,, 16
upper fossil zone with Carlinastraea ,,,,,,,,,, 17

Bootstrap mine area ,,,,,,,,,,,,,,,,,,,,,, 2, 7, 16

Boucot, A, J., cited , HH

Boulder Creek ,,,,,,,,,,

Brachiopods H 4, 5, 8, 10, 14, 15, 16, 17:18, 20, 26, 27
dalmanellid ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 13, 17
pentameroid ,,,,,,,,,,,,,, 9, 10, 11, 13, 19, 20
rhynchonellid ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 20
silicified ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 13
spiriferoid ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27

Brachyelasma ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 30
spb ,,,,,,,,, , HHHHHHHHH 16,31;pl. 12
spa HH ,,,,,,,,,,,,,,,,,,,,,,,,,, 13,31;pl.5

5, 11

Breccias, depositional ,,,,,,,, ,HH ._ H 5, 13, 14, 15

Breuiphrentis ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 30

(Breviphrentisl, Siphonophrentis ,,,,,,,,,,,,,,,,, 30

C

Caesar Canyon Limestone ,,,,,,,,,,,,,, , ...... 23, 24

Calcarenite ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Calceola sandalina ,,,,,,,,

Callaghan window

Calostylis ,,,,,,,,,
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 17, 32, pl, 7

Camerotoechia ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27

Carlin, Nev ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 3, 41

Carlin gold ores, Nev , ,,,,,,,,,,,,,,,,,,,,,,,,,, 2

Carlin Mine ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 7, 16

Carlinastraea ,,,,,,,,,,,,,,,,,,,, 13, 14, 17, 29, 32
beds ,,,,,,,,,,,,,,,,,,,,,,, 13,14,17, 35, 40, 41
giganteum H ,,,,,,,,,,,,,,,,,,,,,,,,,, HH 34
originali’s , , ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 34
tuscaroraensis H 5, 13, 16, 17, 32, 33; pls. 6, 7, 8
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, pl. 8

[Carlinastraea], Spongophyllum ,,,,, , ,,,,,,,,,,,, 33

Cerro Gordo mining district ,,,,,,,,,, 4, 25

Chert granules ,,,,,,,,,,,,,,,,,,,,,,,,, . ,,,,,,,,, 18
nodules ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 26

chimoem, Monograptus ,,,,,,,,,,,,,,,,,,,,,,,,,, 17

Chonaphyllum ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 15, 27
simpsoni ,,,,,,,,,,,,,,,,,,,, 5, 15; p15, 7, 9

Chuckwalla Canyon ,,,,,,,,,,,,,,,,,,,,,,,,,,, 20

Cladopora ,,,,,,,,,,,,,,,,,,,,,,,,,, 10,26, 27; pl. 1
sp. v ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, pl. 10
sp ,,,,,,,,,,,,,,,,,,,,,, 5,10,11,13,15,16,17

Clear Creek , ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 19

Climacograptus medias ,,,,,,,,,,,,,,,,,,,,,,,,,, 11

 

 

 

 

Page

Clinton Group, New York State ,,,,,,,,,,,,,,,,,, 19
Coal Canyon, fault zone A ,,,,,,,, HH 11, 12,13, 35
fault zone, fossils ,,,,,,,,,,,,,,,,,,,,,,,,,,, 14
Simpson Park Mountains ,,,,,,,,,, 2, 5, 11, 13,

14, 15, 16, 17, 20, 28,
29,30, 31,32, 33, 35, 40, 41

Coal Canyon area ,,,,,,,,,,,,,,,,,,,, 11, 15, 40, 41
Coal Canyon basin ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 12
Coal Canyon fault ,,,,,,,,,,,,,,,,,,,,,,, 29, 30, 32
Coelospira ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 17

sp. b ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 16, 17; pl. 12

sp ______________________________________ 10, 17
Coenites sp ,,,,,,,,,,,,,,,,,,,,,,,,, 17

  
  
 
  
  
 
  

 

  

colonus, Monograptus ,,,,,,,,,,,,,,,, H. 13
Conchidium ,,,,,,,,,,,,,,,,,, 9, 20
olaskense ,,,,,,,,,,,,,,,,,,,,,, 33
alaskensis ,,,,,,,,,,,,,,,,, 15
mfinsteri ,,,,,,,,,,,,,,,,,,,, 10; pl, 12
16; pl. 12
_____ pl. 12
Conodonts ________ 2, 4, 11, 15, 16, 18, 19, 26, 28, 29
Copenhagen Canyon ,,,,,,,,,,,,,,,, 3, 7, 11, 18, 40
Roberts Mountains Formation, age ____________ 18
stratigraphic paleontology ,,,,,,,,,,,,,,,, 18
Copenhagen Formation ,,,,,,,,,,,,,,,,,, 19, 24, 25
Coral zone E, age ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
Coral zones, reference section ,,,,,,,,,,,,,,,,,,,, 10
Corals ,,,,,,,,,,,,,,,,,, 2, 4, 5, 8, 14, 16, 20, 22, 24
dissepimented ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 29
nondisspimented ,,,,,,,,,,,,,,,,,,,,,,,,,,, 29
pycnostylid ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27
rugoseHH 1,2, 5, 9, 10, 13, 14, 15, 20, 26, 27, 29
age value ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 29
cerioid __________________________________ 32
colonial ,,,,,,,,,,,, 2, 9, 17,20, 26, 29, 32
key ____________________________________ 29
lykophyllid ,,,,,,,,,,,,,,,,,,,,,, 32; pl. 12
special stratigraphic value ,,,,,,,,,,,,,,,, 29
stratigraphic value ,,,,,,,,,,,,,,,,,,,,,,, 29
zonation ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 28
silicified ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 13
streptelasmids ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5
tabulate ,,,,,,,,,,,,,,,,,,,,,,,,,, 9, 10, 20, 27
alveolitid ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 16
Cordilleran belt ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 32, 33
Cordilleran geosynclinal seaway H. HH. ,,,,,,,,,, 1
Cortez gold ores, Nev ,,,,,,,,,,,,, 2
Cortez Mountains ,,,,,,,,,,,,,,,,,,,,
Cortez quadrangle ,,,,,,,,,,,,,,,,,,,,,,
crateroides, Mucophyllum ,,,,,,,,,,,,,,,,,,,,,,,, 15
Crawford, J. P., cited ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 3
crawfordi, Neomphyma ,,,,,,,,,,,,,,,,,,,,,, 5, 22
Cress, Leland, cited ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2
Crinoids ,,,,,,,,,,,,,,,,,,,,,,,, 4, 8, 14, 17,26, 27
Cryptatrypa

 

 

 

 

  

sp ,,,,,,,,,,,,,,,,,,,
Cyathopaedium ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 31
Cyathophylloides ,,,,,,,,,,,,,,,,,,,,,,, 10, 17, 27, 31

fergusoni H 5, 17, 22, 31

sp. f ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 16, 31; pl. 12
Cyrtograptus sp ,,,,,,,,,,,,,,,,,,,,,,,,,,
Cystihalysites ,,,,,,,,,,,,,,,,,,,,,,,,,,,
(Cystihalysitesl magnitubus, Halysites ,,,,,,,,,,,, 5
Cystiphyllum sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 11
Cystiphylloids ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27

47

48

 

Page
D

Dalmanella sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5
Dalmanophyllum ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10, 26
sp. A ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5, 27
Daly, R, A., cited ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 6
denayensis, Denayphyllum ,,,,,,,,,,,,,,,,,,,, 5, 10
Denayphyllum denayensis ,,,,,,,,,,,,,,,,,, 5, 10
denckmanni, Ozarkodina ,,,,,,,,,,,,,,,,,,,,,,,,, 40
Devonian System ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10
deuonica, Belodella ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4O
devonicus, Scolopodus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40
Dicoelosia sp. r ,,,,,,,,,,,,,,,,,,,,,,,, 5, 10; pl, 11
sp ,H ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5, 10
Dinant Basin, Belgium, standard ,,,,,,,,,,,,,,, 29
Diplophyllum ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10, 27
Dobbin Summit, Monitor Range ,,,,,,,,,,,,,,,,,, 7

Monitor Range,
Roberts Mountains Formation ,,,,,,,,,,,,, 19
Dolomite ,,,,,,,,,,,,,, 1, 3, 8, 9
diagenetic origin ,H 6

 

eastern belt

 

 

facies, ,,H
origin , ,,,,,,,,,,,,, 6
Great Basin, Silurian H, 7

 

 

Guelph, Ontario

  

 

 

 

 

 
   
 
  
 
 
  

hydrothermal type ,,,,,,,,,,,,,,,,,,,,
lithographic ,,,,,,,,,,,,,,,,,,,,,,,,,,
marine, origin ,,HH, 6
penecontemporaneous ,,,,,,,,,,,,,,,,,,,,,,,,, 7
problem ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2
reefs ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
regional H_, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 6, 7
regional problem ,,,,,,,,,,,,,,,,,,,,,, , 6‘
saccharoidal ,,,,,,,,, H 9
Dolomite belts, Great Basin, distribution H H,,,, , 6
Dolomitization ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 7, 26
metasomatic ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 7
regional ,,,,,,,,,,,,,,,,,,,,,, 7
Dry Canyon, Toiyabe Range ,,,,,,,,,,,,,,,,,,,,,, 7
Dry Creek area ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 23,24
dubius, Monograptus ,,,,,,,,,,,,,,,,, 13, 17, 19, 28
duncanae, Tryplasma ,,,,,,,, 5, 10, 13, 17, 31; pl, 3
E
Eantiognathus lipperti ,,,,,,,,,,,,,,,,, ,_H H,, 40
East Northumberland Canyon ,,,,,,,,, 20, 23
Eastern dolomite belt H ,H, 1, 7, 10, 19, 20
Eatonia

  
 
 

 

sp ,,,,,,,,,,,,,,,,,, 10
elegans, Pycnostylus , , H 31; pl. 1
Rotundacodina , , ,,,,,,, 40
Elko County ,HHHHH ,,,,,H,,,,,,,,, H 3, 7,16
Ely Springs Dolomite ,,,,,,,,,,,,,,,,,,,,,,,, 20, 25
Endophyllidae , ,,,,,,,,,,,,,,,,,,,,,,,,, 29, 32, .34
Endaphyllum ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 35
enorme, Rhizophyllum ,,,,,,,,,,,,,,,,,,,, 5, 15
Entelophylloides ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 32
(Prohexagonarial occidentalis ,,,,,,,,,,,, 5, 10
Entelophyllum ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 20
eosteinhornensis, Spathognathodus
Eureka County ,,,,,,,,,,,,,,,
Eureka district , ,,H ,
Eureka Quartzite ,,,,,,,,,,,,,,,,,,,
Evans, J, G,, cited ,,,,,,,,,,,,,,,,,,,,,, ,

 

Evans and Mullens, unnamed Devonian
limestone unit

 

    
   
  

 

     

excavatus, Neoprioniodus ,,,,,,,,,,,,,,,,,,,,,,, 40
extensus, Plectospathodus ,,,,,,,,,,,,,,,,,,, , H 40
F
Fairbridge, R. W,, cited ,,,,,,,,,,,,,,,,,,,,,,,,,, 6
Fardenia sp. b H, ,,,,,,,,,,,,,,,,,,,,,,,, 16; pl. 12
Fault, thrust ,,,,,,,,,,,,,,,,,, H 16
Fauistella , ,,,,,,,, 31
Fauistina ,,,,,,,,,,,,,,,,,,,,, 31
Fauosites H , 11,13,17, 24,26, 27

sp. (1 ,,,,,,,,,,,,,,,, ,, ,,,,, pl. 10

,H pl. 10

, 13, 15, 16

Favositids ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10, 26, 27

 

  

 

 

 

INDEX
Page
fergusom, Cyathophylloides ,,,,,,,,,,, 5, 17, 22, 31
Fish Creek Range ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 20
flemingii, Monograptus ,,,,,,,,,,,,,,,,,,,,,,,,,, 19
F letcheria ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 31
tubifera ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 31; pl. 3
Fletcherina ,,,,,,,,,,,,,,,,,,,,,,, ,H 31
Fossils ,H, , ,,,,,,,,,,,,,,,,,,,,,, , 9
Coal Canyon fault zone ,,,,,,,,,,,,,,,,,,, 14
Mullens section ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 16
Pyramid Hill ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 14
silicifiedH H ,H, 8,14,16, 17,20
unit 1
unit 2 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10
unit 3 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10
f'oveolatus, Polygmzthus ,,,,,,,,,,,,,,,,,,,,,,,,,, 40
f'urnishi, Pelekysgnathus ,,,,,,,,,,,,,,,,,,,,,,,, 40
Fye Canyon area ,,,,,,,,,,,,,,,,,,,,,,,,,,, H,H, 11
G
gaertneri, Ozarkodina ,,,,,,,,,,,,,,,,,,,,,,,,,, 40
Gala beds, England ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 19
Gatecliff Formation ,,,,,,,,,,,,,,,,,,,,,,,,,, 23, 40
Gazelle Formation ,,,,,,,,,,,,,,,,,,, , ,,,,,, 15, 34
geinitzianus angustidens, Retiolites ,,,,,,,,,,,,, 19
giganteum, Carlinastraea ,,,,,,,,,,,, , H, ,,H 34
Glassia ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 17

  

 

Gothograptus spinosus , ._ H ,

 

 

 

       
 

  

Gotland, Sweden , ,,,,,,,,,,,,,,,,,,,,
corals ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2, 30
reefs ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4, 5
rugosa ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4, 15
standard ,,,,,,,
Graptolite facies ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Graptolite standard, age ,,,,,,,,,,,,,,,,,,,,,,,, 17
Graptolite zonation ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 28
Graptolites ,,,,,,,,,,,,,,,, 1, 4, 9, 10,11,131, 14, 15,
17, 18, 19, 22, 23, 24, 25, 26, 28, 29
Great Basin ,,,,,,,,,,,,,,,,,,,,,,,,,, 4, 28
Grays Canyon Limestone Member,
Nevada Formation ,,,,,,,,,,,,,,,,,,,, 30
Graywacke belt, Pacific belt ,,,,,,,,, , HH, , H, 6
Great Basin, brachiopods , .H, HHH H,,,._,, H 4
chert sequencesH ,H: ,,,,,,,,,,,,,,,,,,,,, 11
conodonts ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
coral zonation, Silurian ,,,,,,,,,,,,,,,,,,,, 4, 26
Silurian, reference section H, ,,,,,,, 10, 14
depositional facies belts ,,,,,,,,,,,,,,,, 1
dolomite belts, distribution , ,,,,,,,,,,, 6
eastern dolomite belt ,,,.,,.HH 1, 7, 10, 19, 20
graptolites ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4, 28
intermediate limestone belt ,,,,,,, H 1, 7, 10, 19,
20, 25, 28, 29, 32
limestone facies ,,,,,,,,,,,,,,,,,,,,,,,,,, 4
Silurian ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 32
Lower Devonian, paleontologic zoning , ,,,,,, 4
reference sections ,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
Rugosa, dissepimented ,,,,,,,,,,,,,,,,,,,,,, 32
Silurian, coral zone A ,,,,,,,,, ,_H 4, 10, 16, 17,
22,26, 27, 28, 31
coral zone B,,, H ,,,,,,,,,,,, 4,10,27,28
coral zone C , . H 4,9,10,11,31
coral zone DH_, ,,,,,, 4, 9,10,11,13,16,17,
20,22, 26, 27, 30, 31, 32,34
coral zone E ,,,,,,,, 4, 11,13,14,15,16,17,
22, 23, 26, 27, 29,32, 34, 35
limestones ,,,,,,,,,,,,,,,,,,,,,,,,,, 4
distribution ,HH . 6
paleontologic zoning 4
Great Britain ,,,,, , H , , ,,,,,,,,,,,,,,,,,,,,,,,, 30
Great Lakes, reefs , ,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
Grouse Creek ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 11
Grouse Creek Canyon ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 11
Guelph Dolomite, Guelph, Ontario ,,,,,,,,,,,,,,,, 31
guelphensis, Pycnostylus ,,,,,, , ,,,,,,,,,,,,, 31; pl. 1
Gyptdula ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27
sp. r ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5,10;pl, 11
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 13, 17

Gypsum ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 7

 

 

 

   

     
 
   

Page
H
HalliidaeHHH, ,,,,,,,,,,,,,,,,,,,,,,,,,,,, H 27
Halysites ,,,,,, 10, 11
(Cystihalysites) magnitubus ,,,,,,,,,,,,,,, 5
Sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, H, 5, 10
Hanson Creek dolomite ,,,,,,,,, ,H, ,,,,,,,,,,,, 12
Hanson Creek Formation ,,,,,, 3, 9, 11, 18, 19, 22, 24
Hanson Creek limestone ,,,,,,,,,,,,,,,,,,, , . 12, 13
Heliolites HH,..H,H,H,,,H_, ,,,,,,,, 10, 26, 27
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5, 10, 16, 20
Hemse Group ,H. HHHH , ,HH, ,H .H, ,HH 31
Hercynella , ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, H pl, 10
hercynicus, MonograptusHHHHH..H, ,,,,,,, 19, 25
Hexagonaria ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,H, 25
Hibbardella sp ,.H,
Hidden Valley Dolomite ,,,,,,,,,,, 4, 25, 26, 27, 28
Hindeadella sp , ,. ,,,,,,,,
Hindia ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 26
Homoeospira sp r ,,,,,,,,,,,,,,,,,,,
Horse Creek Valley quadrangle ,,H ,H H
Howellella 5p ,,,,,,,

 

Hsii, K. J., cited , ,
huddlei, Icriodus latericrescens H.

 

     
  

Humboldt River Valley , ,,,,,,,,,,,,,,,,,,,,, 2
l

Icriodus latericrescensH ,,,,,,,,, H, H 40

latericrescens huddlez ,,H ,H, H 40

, ,,,,,,, 40

, H , H 40

Ikes Canyon ,,,,,,,,,,,,,,,,, , 20, 22 32, 34, 35

lkes Canyon window ,, H. ,,H, ,H ,HH, 22. 23,24
August Canyon sequence , H,,, ,H ,H 23,24
June Canyon sequence ,,H H,,,,,,, H 22
Mill Canyon sequence ,,,,, 22, 23, 24, 31 34, 35

inclinatus inL‘linatus, Spathognathodus ,H, H,, , 4O

 
 

 

   

   

inconstans, Trichonodella H H, , 40
Independence quadrangle ,,,,,,, , ,,,,, H, , 25
Independence Range , ,,,,,,,,, ,, HH H, 7
Intermediate limestone belt ,,,,, , H, 1, 7 10, 19, 20,
25, 28, 29, 32

International Stratigraphic Commission H, , 28, 29
Introduction ,,,,,,,,, H. ,,H, , H, , 1
Investigation, history ,,,,,,,,,,,,,,,,,,,,,,,,, 3
purpose ,,,,,,,,,,,,,,,,,,,,,,, H, 2
scope H , 2
Inyo Mountains, CalifH , H, 1, 2, 4, 7, 15, 18, 28, 35
limestones ,. H, ,H, ,,,,,,,, ,,,,H,, 25

InyoRangeH, ,HH H,,,._, HH HH, H, 7

Isorthis sp , ,HHH, , ,,,,,,,,,,,,,,,,,,,,,,, 13
J

jaculum, Monograptus H, 19

Johnson J G, cited H, 2

 

johnsoni Australophyllum (Toquimaphyllum) ,, 5, 14,
15, 17, 22, 23,27, 34,35; pl16

 

 

June Canyon sequence , ,,,,,,,,,,,,,,,,,,,, 22, 23
K
Kay, Marshall, cited H, H,,, .H, ,H, ,,H, H 3
kayi, Arachnaphyllum H, H, HH, H,HHH , 5, 22
Kennett Formation , ,,,,,,,,,,,,,,,,,,,,,,,,,,, 26
Ketophyllum H, ,,H .H, HH,, ,,HHHHHH, H 34
sp, tH ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 34; pl. 10
Klamath Mountains, Calif H , ,,H. 15, 30, 34
Klamathastraea
Kleinhampl, F. J,, quoted ,,,,,,,,,,,,,,,,,,,,,,,, 19
Kodonophyllidae ,,,,,,,,,,,,,,,,,,,,,,,, HH 29, 31
Kodonophyllinae ,,,,,,,,,,,,,,,,,,,,,,,,,, 29,30
Kodonophyllum ,,,,,,,,,,,,,,,,,,,,,, 15, 17, 29, 30
mulleri HH ,,,,,,,,,,,,,,,,,, 5, 15, 29, 30; pl. 4
truncatum H,,,,, ,,H ,,,,,,,,,,,,,,,,,,,,,, 30
sp. b ,,,,,,,,,,,,,,,,,,,,,,,,,,, 29, 30, 32; pl, 5
Kozlowskiellina sp. b , ,,,,,,,,,,,,,,,,, 16, 17; pl. 12
sp. 1" ,,,,,,,,,,,,,,,,,,,,,,,,,,, 5,10,15;pl111
Kyphophyllidae ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 29
Kyphophyllum ,,,,,,,,,,,,, ,H, ,HH, 15, 17, 23,29
nevadensis, ,,H,,,,,, .,,,,H, H,,,,, 5, pl 9
sp. b ,,,,,,,,,,,,, H, HHHH,, , 1’7, 32; pl. 5
Sp 1: ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5, 15; pl 9

Kyphophyllum 7Continued

 

sp. t

 

Laketown Dolomite ,,,,,,,,,,,,,,
Lander County ,,,,,,,,,,,
landerensis, Australophyllum ,
lat‘erierescens, Icnodus H

 
  
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

huddlei, Icriodus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40
subsp. B, Icriodus ,,,,,

Leptaena sp

Leptocoelia ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
beds ................................

Ligonodina sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40

Limestone, argillaceous ......... H H 24, 26
bioclastic H, 13, 14, 16, 23, 25, 26, 28
breccia ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 12, 14, 15
cherty _____________________________________ 24
crinoidal ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 19, 26
dolomitic ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 8, 10
facies, Silurian ______________________________ 32
graptolitic ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 22, 25
intermediate, Silurian ______________________ 6
Inyo Mountains, Calif ,,,,,,,,,,,,,,,,,,,,,,,, 25
marine, reefs ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
Ordovician ,,,,,,,,,,,,,,,,,,

Roberts Mountains __________

Limestones, Inyo Mountains, Calif ,,,,,,,,,,,,,,,, 25
Lower Devonian ,,,,,,,,,,,,,,,,,,,,,,,,,,, 25
Silurian _____________________

geographic distribution H 7

lipperti, Eantiognathus ,,,,,,,,,,,,,,,,,,,,,,,,,, 40

Lobograptus scanicus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 13

Lonchodina walliseri ,,,,,,,,,,,,,,,,,,,,,,,,,, 40
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40

Lone Mountain _____________________________ 3, 9, 10
saccharoidal dolomites ,,,,,,,,,,,,,,,,,,,,,,, 3

Lone Mountain Dolomite ,,,,,,,, 3, 6, 8, 9, 19, 20, 31
dolomite facies ______________________________ 10
lateral equivalence ,,,,,,,,,,,,,,,,,,,,,,,, 3
Roberts Creek Mountain H. ,H ,H 3, 10
saccharoidal ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 9
type section ,,,,,,,,,,,,,,,,,,,,,,,,, H, 3, 20
unit 1 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 20
unit 2 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 9, 2O

Lone Mountain reef ,,,,, 6

Lonsdaleia ,,,,,,,,,,,,,,

Ludlovian faunas ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 11

Ludlovian Stage, Alaska ________________________ 15

Lykophyllids ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 32; pl. 12

M

mcallisteri, Palaeocyclus porpita ,,,,,,,,,,,,,,,,,,, 5
Petrozium 5

McCann Hill Chert, Alaska ,,,,,,

McColley Canyon Formation HH

McKee, E. H,, cited ,,,,,,,,,,,,,,

McMonnigal Limestone _________________________ 9, 22

Maggie Creek, Tuscarora Mountains ,,,,,, 2, 7, 16, 41

magnitubus, Halysites tCystihalysites) ,,,,,, __H 5

Mahogany Hills ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 20

Maikottia ,,,,,,,,,,,,,,,,,,,,, 31
turkestanica H ,,,,,,,,,,,,,,,,,,,, 32
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 32

Masket Shale ______ H ,,,,,,,,,,,,,,,, 3, 19, 23
Bastille Limestone Member ,,,,,,,,,,,,,, 23, 4O

Masursky, Harold, cited ,,,,,,,,,,,,,,,,,,,,,,,,,, 2

Matti, Jonathan C., cited ,,,,,,,,,,,,,,,,,,,,,,,, 2

Mazourka Canyon ,,,,,,,,,,,,,,,,,,,, 2, 4, 25, 28, 35

Mazourka Canyon area H. HH 28

media, Ozarkodina ,,,,,,,,,,,,, 40

medius, Climacograptus ,,,,,,,,,,,,,,,,,,,,,,,,,, 11

Merista sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10, 16

Meristella sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5, 15

M icroplasma ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10

migratus, Paltodus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40

Mill Canyon, Toquima Range __________ 11, 20, 22, 40

Mill Canyon sequence ,,,,,,,,,, 22, 23, 24, 31, 34, 35

Miller, J. W., cited ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2

 

 

 
 
  
  
  
 
 
 
  
  
 
 

INDEX
Page

Monitor Range ,,,,,,,,,,,,,,, H_.HHH 3,7, 11,40
physical stratigraphy ,,,,,,,,,,,,,,,,
Roberts Mountains Formation .....

Dobbin Summit ,,,,,,,,

Monograptids ,,,,,,,,,,,,,,,,,,

Monograptus ,,,,,,,,,,,,,,,,,,,,,, H. , 17, 24
acus ,,,,,,,, _ 19
angustidens A ,,,,,,,,,,,,,,,,,,,, 18
birchensis H

bohemicus ,,,,,, 1 3
chimaem . ,
colonus ,,,,,,,, 13
du bius , ,

flemingu H ........... 19

 

 

 

 

 

 

 

 

  

 

hercynicus _,
jaculum ,,,,,,,,,,,,,,,,
nilssoni-Monograptus scanicus Zone __________ 19
nudus H ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
pandus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
praehercynicus H
priodon ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 19
riccartonensis Zone ,,,,,,,,,,,,,,,,,,,,,,,,,, 11
scanius ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, , ,,,,,,, 28
spiralis ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, l9
tumescens ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 28
uncinatus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 17, 19
uniformis ________ 4, 18, 28
uniformis Zone ,,,,,,,,,,,,,,, ,H 2, 15, 18, 29
uulgaris ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 28
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10,13,17, 19,28
Mount Callaghan, Toiyabe Range ,,,,,,,,,,,,,,,, 7
Mount Lewis area ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 3
Mucophyllum ,,,,,,,,,,,,,,,,,,,,, 15,30
crateroides ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 15
oliueri ,,,,,,,,,,,,,,,,,,,,,, H. 5, 15, 30; pl, 4
Mudflats ,,,,,,,,,,,,,,,,,,,,,,,,,, , ,,,,,,,,,,,,, 7
Mullens, T. E,, cited ,,,,,,,,,,,,, HH 2,16,17
Mullens section ,,,,,,,,,,,,,,,,,,,,,,,,,,,, , 16, 17
mulleri, Kodonophyllum ,,,,,,,,,, 5, 15, 29, 30; pl. 4
multiformis, Neoprioniodus ,,,,,,,,,,,,,,,,,,,,,,, 40
mflnsteri, Conchidium , ,,,,,,,,,,,,,,,,,,,, 10; pl, 12
Murray, R. C, cited ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 6
Mycophyllinae ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 29, 30
N
Neophyma ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 33
crawfordi ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5, 22
Neoprioniodus excavatus ,,,,,,,,,,,,,,,,,,,,,,,, 40
multiformis ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40
Nevada Formation ,,,,,,,,,,,,,,,,,,,,,,,, 3, 10, 30
Beacon Peak Dolomite Member ,,,,,,,,,, 3, 10
Grays Canyon Limestone Member ____________ 30
nevadensis, Kyphophyllum , ,,,,,,,,,,,,,,,,, 5; pl. 9
Stylapleura ,,,,,,,,,,, H_ 5, 15, 17, 22, 32; pl. 2
newfarmeri, Tryplasma ,,,,,,,,,,,,,, 5, 10, 31; pl, 3
Niagaran Series, reefs ,,,,,,,,,,,,,,,,,,,,,,,, 4, 5
noguerensis, Rotundacodina ,,,,,,,,,,,,,,,,,,,,,, 40
Northumberland area, Toquima Range ,,,,,,,,,,,, 7
Northumberland window ,,,,,,,,,,,,,,,,,,,,,,,,, 23
Prospect sequence ,,,,,,,,,,,,,,,,,,,,,,,,,,, 23
Striped Hill sequence ,,,,,,,,,,,,,,
nudus, Monograptus ,,,,,,,,,,,,,,,,,,
O
occidentalis, Entelophylloides (Prohexagonaria) H 5, 10
oliveri, Mucophyllum ,,,,,,,,,,,,,,,, 5, 15, 30; pl. 4
Oneotodus beckmanni ,,,,,,,,,,,,,,,,,,,,,,,,,,, 40
originalis, Curlinastraea ,,,,,,,,,,,,,,,,,,,,,,,, 34
Orthophyllum sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10
Orthostrophia sp ,,,,, 5, 15
Ozarkodina denckmanni
gaertneri ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
media ,,,,,,,,,
typiCa ,,,,,,,,,,,
Ziegleri ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
P
Pablo Canyon, Toiyabe Range ____________________ 7

 

Pablo Canyon area HH

 

49

Page

Pacific Border graywacke belt ,,,,,,,,,,,,,,,,, 1, 6
Pacific border province ,,,,,,,,,,,,,,,,,,,,,,,,,, 1
Palaeocyclus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10, 27
porpzta mcallisteri ,,,,,,,,,,,,,,,,,,,,,,,, 5
Palaeophyllum ................................ 10, 31
sp. b ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 20
Paleontologic zoning, Great Basin ,,,,,,,,,,,,,,, 4
Paleozoic rocks ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 11
Paltodus migratus , ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4O

 
 
 
 

 

  
 
 
 
  

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

Panamint Mountains ,,,,,,,,,,,,,,,,,,,,,,,,
Panderodus sp ,,,,,,,,,,,,,,,,,,
pandus, Monograptus H, ,
Pelekysgnathus furmshi ,,,,,,,,,,,,,,,,,,,,,,,, 40
513 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40
Pentamerus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, H_. 20
Perdido Formation ,,,,, , 25
Persian Gulf ,HH,, 7
Pete Hanson Creek ,,,,,, 9
Pete Hanson Creek area 10
Petes Canyon ,,,,, ,. 20
Petes Canyon window ,,,,,,,,,,,, , ,,,,,,,,, H 22, 24
Petrozium
mcallisterz ,,,,,,,,,,, . 5
Pine Hill ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 11,12
age H. H ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 13
stratigraphic paleontology ,,,,,,,,,,,,,,,,,,, 13
Pine Hill section, physical stratigraphy HH 12, 14, 15
Plectatrypa sp. c ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, pl. 11
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5, 15, 27
Plectaspathodus alternatus ,,,,,,,,,,,,,,,,,,,,,, 40
extensus .H ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40
Point of Rocks area ,,,,,,,,,,,,,,,,,,,,,,, 23, 24, 25
Polygnathus faveolatus ,,,,,,,,,,,,,,,,, H. .H 40
Porcupine River, Alaska ,,,,,,, 32
porpita mcallisteri, Palaeocyclus ,,,,,,,,,,,,,,,,,, 5
praehercynicus, Monograptus ,,,,,,,,,, 13, 19, 22, 29
Pray, L. C., cited ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 6
primus, Spathognathodus ,,,,,,,,,,,,,,,,,,,,,,, 40
priodon, Monograptus‘ ,,,,,,,,,,,,,,,,,,,,,,,,,,, 19
Prioniodina sp ,,,,,,,,,,, HHH 40
(Prohexagonarial occidentalis, Entelophylloides _ , 5, 10
Prospect sequence, chert unit , , ,,,,,,,,,,,,,,,,, 23
Ptychopleurella sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10, 16
Pycnactis Sp. K ,,,,,,,,,,,,,,,,,,,,,,,, , ,,,,,,,,, 5
Pycnostylid _ ,,,,,,,, HH HH 10, 14, 15, 31
Pycnostylidae ,,,,,,,,, . ,,,,,,,,,,, 29, 31
cerioid ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 32
Pycnostylus ,,,,,,,,,,,,,,,,,,,,,,,,,,,, , _____ 15, 31
elegans ,,,,,,,,,,,, HH 31; pl, 1
guelphensis ,,,,,,, HH 31; pl, 1
sp. 1 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 31; pl, 2
Pyramid Hill , ,,,,,,,,,,,,,,,,,,,,, 11, 12, 14
Silurian-Devonian Boundary ,,,,,,,,,,,,,,,, 15
Pyramid Hill section ,,,,,,,,,,,,,,,,,,,,,,,, 13, 14
physical stratigraphy ,,,,,,,,,,,,,,,,,,,,,,,, 14
R
Rabbit Hill ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 18
Rabbit Hill Limestone ,,,,,, 11, 14, 15, 16, 18, 19, 22,
23, 27, 34, 40, 41
Ravenswood area, Shoshone Range ,,,,,, .H 7, 25
Red Hill ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 11, 14
Reeds Canyon, Toiyabe Range ,,,,,,,,,,,,,,,,, 7, 24
Reef, Lone Mountain ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 6
Reefs, building ,,,,,,,,,,,,,,,,,,,, 5
core rock ,,,,,,,,,,,,,,,,,,,,,, 5
dolomite ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
Gotland, Sweden ,,,,,,,,,,,,,,,,,,,,,,,,,, 4, 5
Great Lakes ,,,,,,,,,,,,,,,,,,,,,,,,, 4
marginal beds ,,,,,,,,,,,,,,,,,,,,,,,, H 5
marine limestone ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
Niagaran Series ,,,,,,,,,,,,,,,,,,,,,,,,,, 4, 5
patch ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5
Roberts Mountains Formation, scarcity ,,,,,,,, 4
scarcity ,,,,,,,,,,,,,,,,,,,,,,,,

remscheidensis, Spathognathodus HH
Spathognathodus steinhornensis H
resima, Belodella ,,,,,,,,,,,,,,,,,,,,

 

50

 

 

 

 

 

 

 

 

 

Resserella sp ,,,,,,,,,,,,,,,,,,,,,,,,,
Retiolites geinitzianus angustidens ,,,,,
Rhabdocyclus sp, B ,,,,,
sp. d ,,,,,,,,,,,,,,
Rhegmaphyllum Sp, h ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 13, 17
hazophyllum ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 15, 33
enarme ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5, 15
sp, D ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5, 27
Rhynchaspirina sp ,,,,,,,,,,,,,,,,,,,,,,,,,, 5, 15
Roberts Creek Mountain ,,,,,,,,,,,,,, 3, 7, 9, 10, 19
Roberts Mountains, Nev ,,,,,,,,,,,,,,,,,,,,,,, 7, 14
rugosa ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, , 4
Silurian limestones ,,,,,,,,,,,,,,,,,,,,,, 3
Roberts Mountains Formation, age ,,,,,, 1, 2, 11, 20
August Canyon sequence ,,,,,,,,,,,,,,,, 23, 24
Bare Mountain ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 20
black chert unit ,,,,,,,,,,,,,,,,,, 22, 23, 24, 25
Bootstrap Hill section, age ,,,,,,,,,,,,,,,,,, 17
physical stratigraphy ,,,,,,,,,,,,,,,,,,,, 16
stratigraphic paleontology ,,,,,,,,,,,, 16, 32
Brock Canyon, Monitor Range ,,,,,,,,,,,,,,,, 19
Callaghan window ,,,,,,,,,,,,,,,,,,,,,, 23, 24
chert marker ,,,,,,,,,,,,,,,,,,,,,,,,, 18, 19, 20
cherty dolomite member ,,,,,,,,,,,,,,,,,,,, 20
Coal Canyon area ,,,,,,,,,,,,,,,, 11, 14, 15,35
Coal Canyon fault zone ,,,,,,,,,,,,,,,,,,,,,, 11
Coal Canyon section ,,,,,,,,,,,,,,,,,, 4, 16, 20
conodonts ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2
Copenhagen Canyon ,,,,,,,,,,,,,,,,,,,,,, 3, 18
age ______ 18
stratigraphic paleontology ,,,,,,,,,,,,,, 18
Cortez Mountains ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 3
Dobbin Summit, Monitor Range ,,,,,,,,,,,,,, 19
dolomite facies ,,,,,,,,,,,,,,,,,,,,,,,,,,, 3, 10
origin ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 6
dolomite problem ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2
Dry Creek area ,,,,,,,,,,,,,,,,,,,,,,,,,, 23,24
facies changes ,,,,,,,
geologic mapping .....
geologic setting ,,,,,,,,,,,,,,,,,,,,,,
gold ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 3
graptolite faunas ,,,,,,,,,,,,,,,,,,,,,,,,,,, 3
Great Basin ,,,,,,,,,,, 1, 4
Ikes Canyon window ,,,,,,,,,,,,,,,,,, 22, 23, 24
June Canyon sequence ,,,,,,,,,,,,,,,,,,, 22, 23
lateral equivalence ,,,,,,,,,,,,,,,,,,,,,,,,,, 3
limestone ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 1, 5, 14
limestone facies ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10
lithology ,,,,,,,,,,,,,,,,,,,, 5, 8, 9, 12, 13, 16,
18, 19, 20, 23, 24
lower coral zone with Carlinastmea 1111111111 14
Mill Canyon sequence ,,,,,, 22, 23, 24, 31, 34, 35
Monitor Range ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 18
physical stratigraphy ,,,,,,,,,,,,,,,,,,,, 18
Pablo Canyon area ,,,,,,,,,,,,,,,,,,,,,, 23,25
Petes Canyon window ,,,,,,,,,,,,,,,,,,,, 22, 24
Pine Hill, age ,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,_ 13
stratigraphic paleontology ,,,,,,,,,,,,,,,, 13
Pine Hill section ,,,,,,,,,,,,,,,,,,,,,, 12, 14, 15
Point of Rocks area ,,,,,,,,,,,,,,,,,, 23, 24, 25

 

Prospect sequence
Pyramid Hill, Silurian-Devonian

Boundary, problem ______ c. 15
Pyramid Hill section ,,,,,,

   
 

   
  
   
  
 

 

physical stratigraphy ,,,,,,,,,,, h 14
redefinition 2
reefs, scarcity ,_, 4
reference section ,,,,,,,,,,,,,,,,,,,,,, 4, 16, 17
Roberts Creek Mountain ,,,,,,,,,,

Roberts Mountains, Nev ________

Shoshone Mountains ,,,,,,,,,,

Shoshone Range _______________ 3
Silurian limestones ,,,,,,,,,, __c_ 4
Simpson Park Mountains ._ 3, 11

Straight Canyon area ___-
stratigraphy ,,,,,,,,,,,
stratigraphic paleontology,
stratigraphic relations .
Striped Hill sequence H, __________________ 23

 

 

 

 

 

 

INDEX
Page
thickness ,,,, 9,12,13, 14, 16, 18,19, 20, 22, 25
Toiyabe Range ,,,,,,,,,,,,,,,,,,,,,,,,,, Z3, 25
Toquima Range ,,,,,,,,,,,,,,,,,,,,,, 3, 20, 24
Tuscarora Mountains ,,,,,,,,,,,,,,,,,,,,,,,, 15
type area ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 7, 8, 10
type section ________________ 3, 9, 10, 16, 17, 20
age ' ,,,,,,,,,,,,,,, 10
unit 1 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 9, 11
unit 2 ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 9, 10, 11,20
unit 3 _________ , fl ,,,,, 9, 10, 11, 31
upper coral zone with Toquimaphyllum ,,,,,, 14
Roberts Mountains thrust ________________________ 22
August Canyon sequence ,,,,,,,,,,,,,,,,,,,, 23
Ikes Canyon window ,,,,,,,,,,,,,,,,,,,, 22, 23
June Canyon sequence ,,,,,,,,,,,,,,,,,, 22, 23
Mill Canyon sequence ____________________ 22, 23
Northumberland window ,,,,,,,,,,,,,,,,,,,, 23
Petes Canyon window ,,,,,,,,,,,,,,,,,,,,,,,, 22
Roberts, R, J., cited ___________________________ 2, 16
Rocky Hills thrust ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 12
Ross, D, C., cited ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2
Ross, R, J., Jr., cited ,,,,,,,,,,,,,,,,,,,,,,,,,,, 28
Rotundacodina elegans 11111111111111111111111111 40
noguerensis ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40
Round Mountain ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 25
Rugosa ______ 2, 4, 5, 10, 13, 14, 15, 17,25, 26, 27, 29
age value ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 29
assemblages ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 15, 27
Australia ,,,,,,,,,, 4, 15
cerioid ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 32
colonial ,,,,,,,,,,,,,,,, 2, 9, 17, 20, 26, 29, 32
dissepimented ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 32
eastern Europe ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
England ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
Getland, Sweden ,,,,,,,,,,,,,,,,,,,,,,,, 4, 15
key ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 29
Klamath Mountains, Calif ,,,,,,,,,,,,,,,,,, 15
lykophyllid ,,,,,,,,,,,,,,,,,,,,,,,,,, 32; pl. 12
nondissepimented, Silurian ,,,,,,,,,,,,,,,,,,, 29
pycnostylid ,,,,,,,,,,,,,,,,,,,,,,,,,,, 10, 14, 15
Silurian ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4, 15
Silurian, stratigraphic distribution ,,,,,,,,,,,, 4
special stratigraphic value ,,,,,,,,,,,,,,,,,, 29
stratigraphic value ,,,,,,,,,,,,,,,,,,,,,,,,,, 29
zonation ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 28
Ryderophyllum ubehebensis ,,,,,,,,,,,,,,,,,,,,,, 5
S
Salairaphyllum 111111111111111111111111111111 15, 33
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5
Salopina ,,,,,,,,,,,,,,,
sp ,,,,,,,,,,,,,,,,,,
sandalina, Calceola ,,,,,,,,,,,,
scalaris, Climacograptus
scanic us, Lobograptus ,,,,,,,,,,
scanius, Monograptus ,,,,,,,,,,
Schellwienella sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5, 15
Schizopharia ,,,,,,,,,,,,,,,,,,,,,,,,,,, h 27
Schlotheimophyllum ______

 

Schneider, J., cited 1.1 ,,

 

Schuchert, Charles, cited .. , 6
Scolapodus deuanicus ,,,,,,,,,, _. 40
sedgwicki, Spongophyllum 11111 , , pl. 6
Shales, graptolitic ,,,,,,,,,,, 16
Shale-graywacke facies , ______ 7
Shoshone Mountains, Nevi 2
Shoshone Range ,,,,,,,,,,,,,, 3
Sicorhyncha sp ,,,,,,,,,,,,,,,,,,, 5, 15
Silurian-Devonian boundary 1, 2, 11, 15, 17
central Nevadai 1. ,,,,,,,,, 28
problem ,,,,,,,,,,,,,,,,,,, 15
Pyramid Hill -1 ,,,,,,,,,,,,,, 15
Silurian-Devonian Boundary Committee 1, __ 28, 29
Silurian limestone, Great Basin, distribution ______ 6
Silurian limestones, geographic distribution cccccc 7
Silurian System ,,,,,,,,,,,,,,,, 4, 10, 15, 19, 26, 31
Silurian zone 5b, Norway ________________________ 10
Simpson Park Mountains ,,,,,,,,,, 2, 3, 7, 14, 16, 17,
32, 35, 40

simpsoni, Chonophyllum ,,,,,,,,,,,,,, 5, 15; pls. 7, 9

 

 
   
 
 
   
 
  
  
 
 
  

 

 

 

 

 

 

 

  
 
 

 

 

   

Page
simpsoni, Chonophyllum—Continued
Tonkinaria ,,,,,,,,,,,,,,,,,, 5, 10, 13, 32; pl. 5
Siphonophrentis (Breviphrentis) m
Skeats, E. W., cited ,,,,,,,,,,,,,,,, 6
Spathognathodus eosteinhornensis ,,,,,,,,,,,,,,,, 40
inclinatus inclinatus ,,,,,,,,, , ,,,,,,,,,,,,,,, 40
primus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40
remscheidensis ,,,,,,,,,,,,,,,,,,,,,,,,, 40
steinhornensis remscheidensis ,,,,,,,,,,,,,,,, 40
transitans ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40
spinosus, Gothogmptus ,,,,,,,,,,,,,,,,,,,,,, 19
spiralis, Monograptus ,,,,,,,,,,,,,,,,,,,, "h 19
Sponge ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, A," 26
Spongophyllidae ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 29, 32
Spongophylloides ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 33
Spongaphyllum _,, ,,,,,,,,,,,,,,,,,,,, 17, 32,33
sedgwicki _______________________ 32, 33; pl, 6
[Carlinastmea] _,
sp. A
sp, B ,,,,,
Stauriidae ,1, "a. ,_,c
Steidtmann, Edward, cited ,,,,,,,,,,,,,,,,,,,,,, 6
steinhornensis remscheidensis, Spathognathodus 1, 40
Stevens, C, H,, cited ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2
stevensi, Australophyllum ,,,,,,,,,,,,,,,,,,,,,,,, 28
Stewart, J. H., cited ,,,,,,,,,,,,,,,,,,,,,,,,,,,
Straight Canyon area ,,,,,,,,,,,,,,
Streptelasma ,,,,,,,,,,,,,,,,,,,,,,,,,,,
Streptelasmatidae ,,,,,,,,,,,,,,,,,,,,,
Striatapora sp ,,,,,,,,,,,
Striped Hill sequence ,,,,,
Stromatoporoids ,,,,,,,,,,,,,,,,,,,, 4, 5, 15, 26, 27
Stylopleum ,,,,,,,,,,,,,,,,,,,,,,,,, 13, 14, 15, 17,31
berthiaumi ,,,,,, 5, 10, 13, 15, 20, 31,32; pls, 1, 2
neuadensis ,,,,,,,,,,,,,,,,, 5, 15, 17, 22, 32; pl. 2
sp. b ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 17,32; pl, 1
sp. c ,,,,,,,,,,,,,,,,,,,,,,,, 13, 14,32; pls. 1, 2

 

 

sp _______________
Sunday Canyon Formation
age
Swales Mountain , , , ,
Synprioniodina sp , ,
Syringaxon _ . _
sp ,,,,,,,
Syringopora ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 13

  
 
 
 

T

  
 
 
     

Tabulophyllum ccccccc
Tentaculites ,
Thrust fault .
Thrust plates ,.

 

,,,,,, 18,19, 22, 23, 24

 

     

 

 

 

 

 

 

 

 

 

Toiyabe Range ,,,,,,,,,,,,,,,,,,,,,,,, 2, 18, 23, 25
Tankinaria ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 13
simpsoni A ,,,,,,,,,,,,,,,, 5,10, 13, 32; pl, 5

sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 22
Toquima Range ,,,,,,,,,, 2, 3, 7, 11, 17, 18, 19,
23, 24, 25, 34,35, 40

Ikes Canyon area ,,,,,,,,,,,,,,,,,,,,,,,, 32, 35
Mill Canyon sequence _, ., 22, 23, 24, 31, 34, 35
Roberts Mountains Formation ,,,,,,,,,, 3, 20, 24
Toquimaphyllum ,,,,,,,,,,,,, 14, 15, 34, 35
beds ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 13
(Toquimaphyllum), Australaphyllum 111111 29, 34, 35
johnsoni, Australophyllum __________ 5, 14, 15, 17,

22, 23,27, 34, 35; pl. 6

sp., Australophyllum ,,,,,,,,,,,,,,,,,,,,,,,, 27

Tor Limestone ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 22
Torquay, Devonshire, England ,,,,,,,,,,,,,,,,,,,, 33
transitans, Spathognalhodus _______ 40
Trematospira ,,,,,,,,,,,,,,,,,,,,, 27
sp ,,,,,,,,,,,,,,,,,,,,, 17
Trichonodella blanda 1111111 40
inconstans ,,,,,, 40

sp .............. 40
Trilobite ,,,,,,,,,,,, 26
cryptolithoid __ _, 24
truncatum, Kodanaphyllum 1111111111111111111111 30

 

  

 

 

Page

Tryplasma ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10, 13, 33

dueranae _ ,,,,,,,,,,,,,, 5,10, 13, 17, 31; pl. 3

newfarmeri ,,,,,,,,,,,,,,,,,,,, 5, 10, 31:131. 3

so g ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 31; pl. 3

“MN"... 13,17

Tryplasmatidae ,,,,,,,,,,,,,,,,,,,,,,,,,,, 29, 31

Tryplasmid ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27, 31

tubifera, Fletcheria ,,,,,,,,,,,,,,,,,,,,,,,,, 31; pl, 3

tumescens, Monograptus ,,,,,,,,,,,,,,,,,,,,,,,,,, 28

turkestanica, Maikottza ,,,,,,,,,,,,,,,,,,,,,,,,, 32

Tuscarora Mountains, Nev ____________ 2, 3, 7, 9, 11,

15,16, 30, 34, 41

tuscaroraensis, Carlinastraea ___________ 5, 13, 16, 17,

32, 33; pls. 6, 7, 8

typica, Ozarkodina ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40

U

ubehebensis, Ryderophyllum ,,,,,,,,,,,,,,,,,,,,,, 5

Ulrich, E. 0,, cited ,,,,,,,,,,,,,,, 6
uncinatus, Monograptus ,,,,,,,,,,,

uniformis, Monagraptus ,,,,,,,,,,,,,,,,,,,, 4, 18, 28

Ural Mountains, U.S.S.R ,,,,,,,,,,,,,,,,,, 15, 33, 34

 

 

 

 

INDEX
Page
V

Van Tuyl, F. M,, cited ,,,,,,,,,,,,,,,,,,,,,,,,,, 6
Vaughn Gulch ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 25
Vaughn Gulch Limestone ,,,,,,,, 1, 15, 18,25, 34, 35
age ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27
black chert zones ______________________________ 25
chert member , 3 ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 26
coral zone A ________________________________ 27
coral zone E ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27
lower division ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 26

middle division ,,,,,,,,,,,,,,,,

physical stratigraphy ,,,,,,,,,,
stratigraphic paleontology ,,,,,,,,,,,,,,,,,,,, 26
thickness ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 26
type section... _________________________ 25, 26
upper, fossils _... ____________________________ 27
upper division ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 26
Verticillopora beds ,,,,,,,,,,,,,,,,,,,,,,,,,, 27
Vaughn Gulch limestone unit __________________ 15
Verticillopora ,,,,,,,,,,,,,,,,,,,,,, 4, 15, 26, 27, 29
ranges ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4

annulata "H 5, 10,14, 15, 22, 26, 27; pls. 10,11

 

 

51

 
 
  
 
 

 

Page
Verticillopora—Continued
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5; pl. 10
Vinini Formation , 111 16
Virgiamz sp ,,,,,,,,, ,, 20
vulgaris, Monograptus _________________________ 28
W
Wall Canyon, Toiyabe Range ,,,,,,
walliseri, Lorwhadina ,,,,,,,,,,,,,,
Water Canyon ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 23
Wenban Limestone ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 9
West Northumberland Canyon ,,,,,,,,,,,,,,,,,, 20
Western graywacke belt ,,,,,,,,,,,,,,,,,,,,,,,,,, 1
Willow Creek ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 7
Windmill Limestone ,,,,,,,,,,, 9, 11, 13, 14, 16, 19, 40
Y, Z
Ya'ssia ____________________________________________ 32
Zelophyllum sp ,,,,,,

 

z'wgleri, Ozarkodina , ,

 

 

 

 

 

PLATES l— 12

[Contact photographs of the plates in this report are available, at cost, from the US. Geological Survey Photographic Library,
Federal Center, Denver, Colorado 80225]

 

 

PLATE 1

FIGURES 1—9. Stylopleura berthiaumi Merriam
1-6. Great Basin Silurian coral zone D. Roberts Mountains Formation, unit 3. Locality
M1100, Roberts Creek Mountain, Nev.
1. View ofbroken calice interior showing three offsets. Paratype, USNM 159384a. X2.
2. Lateral view of two corallites from a large colony (paratype USNM 165359) showing
connecting elements. X 1.
3. Calice View showing multiple calice budding. Paratype USNM 159383. X2.
4. Partial lateral View of holotype. USNM 159382. X11/2.
5. Partial lateral View of paratype showing lateral element attached to Cladopora
branch. USNM 159384. X1.
6. Longitudinal thin section. USNM 165358a. X2.
7—9. Great Basin Silurian coral zone E. Roberts Mountains Formation. Locality M1106,
Coal Canyon, Simpson Park Mountains, Nev. USNM 159385. X1.
7. Lateral view.
8. Calice view.
9. Partial interior view showing calice offsets.
10—12. Stylopleura sp. b
10—11. Silurian Roberts Mountains Formation. Locality M1314, Bootstrap Hill, Tuscarora
Mountains, Nev.
10. Lateral View of broken corallite. X 11/2.
11. Lateral view of piece of corallite showing base of hollow lateral element. X2.
12. Longitudinal thin section. X2. Silurian. Roberts Mountains Formation. Locality
M1315, Bootstrap Hill, Tuscarora Mountains, Nev.
1&15. Stylopleura sp. c, cf. S. berthiaumi
Great Basin Silurian coral zone D. Roberts Mountains Formation. Locality M1317, Coal
Canyon, Simpson Park Mountains, Nev. X2.
13. Longitudinal thin section.
14, 15. Transverse thin sections.
16, 17. Pycnostylus guelphensis Whiteaves?
Longitudinal and transverse sections. X2. Unenlarged copies of plate X, figures 4, 4a in
Lambe (1901). Silurian, Guelph Dolomite; Ontario, Canada.
18, 19. Pycnostylus guelphensis Whiteaves.
Unenlarged copies oftwo of Whiteaves’ type illustrations (Whiteaves, 1884, pl. 1, figs. 1a, b).
Silurian, Guelph Dolomite; Ontario, Canada. X1.
18. Transverse section of corallum.
19. Lateral view of broken corallite with two remaining offsets; note lack of exterior
longitudinal ribbing.
20. Pycnostylus elegans Whiteaves.
Anterior end of a mature corallite with several offsets. Note external ribbing. X 1. Unen-
larged copy of one of Whiteaves’ (1884) type illustrations.
Silurian, Guelph Dolomite; Ontario, Canada.

GEOLOGICAL SURVEY PROFESSIONAL PAPER 973 PLATE 1

 

‘0 v. '-
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STYLOPLEURA AND PYCNOSTYL US

PLATE 2

FIGURES 1, 2. Stylopleura? sp. c
Transverse and longitudinal thin sections. X2. Silurian, Roberts Mountains Formation.
Locality M1379, Coal Canyon, Simpson Park Mountains, Nev.
3—6. Stylopleura neuadensis Merriam
Great Basin Silurian coral zone E. Roberts Mountains Formation. Coal Canyon, Simpson
Park Mountains, Nev.
3, 4. Longitudinal and transverse thin sections of same colony. Paratype, USNM
159431a. X2. Locality M1380.
5. Upper surface of holotype, USNM 159431. X1/2. Locality M1107.
6. Longitudinal thin section of holotype showing a lateral connecting element. USNM
159431. X2. Locality M1107.
7. Stylopleura cf. S. nevadensis n. gen., n. sp.
Longitudinal thin section. X2. Great Basin Silurian coral zone E. Roberts Mountains For-
mation. Locality M1381, Coal Canyon, Simpson Park Mountains, Nev.
8, 9. Stylopleura berthiaumi Merriam
Great Basin Silurian coral zone D. Locality M1103, Ikes Canyon, Toquima Range, Nev.
8. Lateral View of flaring calice. X1.
9. Lateral View of same individual showing connecting element. X 1.
10. Pycnostylus sp. 1
Longitudinal thin section. X3. Silurian, Lone Mountain Dolomite. Locality M1148, south-
ern Sulphur Spring Mountains, Nev.; 4.8 km south of Romano Ranch.

GEOLOGICAL SURVEY PROFESSIONAL PAPER 973 PLATE 2

A}. ‘,

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STYL OPLEURA AND PYCNOSTYL US

PLATE 3

FIGURES 1—7. Fletcheria tubifera Edwards and Haime.
1. Lateral view of corallum. Copy of original type figure of Edwards and Haime (1851, pl.
16, fig. 5). Silurian, Gotland, Sweden. X11/2.
2—7. Silurian, Slite Group (Wenlockian); Slite, Lannaberget, Gotland, Sweden.
2. Lateral View of corallum showing corallite surface ornamentation. X2.
3. Transverse thin section. X2.
4, 5. Longitudinal thin sections. X2.
6, 7. Transverse sections showing multiple calice offsets and wall structure. Note ab-
sence of septa. X6.
8, 9. Tryplasma duncanae Merriam
Great Basin Silurian coral zone D. Roberts Mountains, Formation, unit 3. Locality M1100,
Roberts Creek Mountain, Roberts Mountains, Nev.
8. Lateral View of holotype, USNM 159374. X2.
9. Oblique calice view of paratype, USNM 159375. X5.
10—15. Tryplasma newfarmeri Merriam
Great Basin Silurian coral zone C. Roberts Mountains Formation, unit 3. Locality M1102,
Roberts Creek Mountain, Nev.
10, 11. Longitudinal thin sections of holotype, USNM 159377. X3.
12, 13. Longitudinal thin sections of holotype, USNM 159377. X8.
14, 15. Transverse thin sections of holotype, USNM 159377. X8.
16—19. Tryplasma sp. g
These figures are all of the same corallum. Silurian, Hemse Group (Ludlovian); locality
M1382, Gotland, Sweden.
16. Transverse thin section. X2.
17. Transverse thin section. X4. Enlargement of part of figure 16.
18, 19. Longitudinal thin sections. X2.

PROFESSIONAL PAPER 973 PLATE 3

GEOLOGICAL SURVEY

 

FLETCHERIA AND TR YPLASMA

PLATE 4

FIGURES 1-4. Mucophyllum oliueri Merriam
Great Basin Silurian coral zone E. Locality M1108, Coal Canyon, Simpson Park Moun-
tains, Nev.
1. Longitudinal section of paratype, USNM 159391. Photographed in water. X1.
2. Transverse section of holotype, USNM 159390. Smoothed surface photographed in
water. X 1.
3. Longitudinal thin section of holotype. USNM 159390. X4.
4. Part of transverse thin section of holotype, USNM 159390, showing pattern of
trabeculae. X2.
5, 6. Kodonophyllum mulleri Merriam
Transverse and longitudinal thin sections of holotype, USNM 159386. X44 Great Basin
Silurian coral zone E. Locality M1107, Coal Canyon, Simpson Park Mountains, Nev.

PROFESSIONAL PAPER 973 PLATE 4

GEOLOGICAL SURVEY

 

MUCOPHYLL UM AND KODONOPHYLL UM

PLATE 5

FIGURES 1—14. Tonkinaria simpsoni Merriam
1—9. Great Basin Silurian coral zone D. Roberts Mountains Formation, unit 3. Locality
M1100, Roberts Creek Mountain, Roberts Mountains, Nev.
1, 2. Lateral (XII/2) and calice (X2) Views of paratype, USNM 159402.
3, 4. Transverse (X4) and longitudinal (X31/2) thin sections of paratype, USNM 159404.
5. Transverse thin section. USNM 159405. X2.
6. Calice View. X2.
7. Longitudinal thin section of same individual. X3.
8, 9. Lateral exterior and calice Views of holotype, USNM 159403. X 11/2.
10—14. Great Basin Silurian coral zone D. Roberts Mountains Formation. Locality M1383;
Coal Canyon, Simpson Park Mountains, Nev.
10. Oblique lateral View of corallum showing bases of three offsets at calice rim. X2.
11-13. Calice rim of three coralla showing offsets. X2.
14. Calice view. X2.
15—21. Kyphophyllum sp. b
Silurian, Roberts Mountains Formation. Locality M1314; Bootstrap Hill, Tuscarora Moun-
tains, Nev.
15. Lateral View of corallite showing a single offset. X2.
16. Lateral view of partial corallum X2.
17. Lateral View of calice interior. X2.
18, 19. Transverse and longitudinal thin sections of corallite. X3.
20, 21. Transverse and longitudinal thin sections of corallite. X3.
22—24. Kodonophyllum sp. b.
Transverse and longitudinal thin sections of three corallites. X3. Silurian, Roberts Moun-
tains Formation. Locality M1314, Bootstrap Hill, Tuscarora Mountains, Nev.
25, 26. Brachyelasma sp. c.
Transverse and longitudinal thin sections of same individual. X11/2. Great Basin Silurian
coral zone D. Roberts Mountains. Formation. Locality M1383; Coal Canyon, Simpson
Park Mountains, Nev.

GEOLOGICAL SURVEY PROFESSIONAL PAPER 973 PLATE 5

 

TONKINARIA, KYPHOPHYLL UM, KODONOPHYLL UM, AND BRA CHYELASMA

PLATE 6

FIGURES 1—4. Spongophyllum sedgwicki Edwards and Haime.
Copies of original figures of the type material of Edwards and Haime (1850—54, pl. 56, figs.
2a, c, d, e). Torquay, England; according to Edwards and Haime from the Devonian strata.

1. Transverse section enlarged (Edwards and Haime, fig. 2d, >< 11/2).

2. Longitudinal section enlarged (Edwards and Haime, fig. 2e, ><1‘/2). This section is
conceivably from same corallum as figure 1.

3, 4. Transverse sections enlarged (Edwards and Haime, figs. 2c and 2a, >< 11/2). These
figures probably do not represent the same species and are possibly not congeneric
with corals illustrated by figures 1 and 2 of this plate.

5—7. Carlinastraea tuscaroraensis n. gen, n. sp.

5. Transverse thin section. ><3. Great Basin Silurian coral zone D. Roberts Mountains
Formation. Locality M1384, Coal Canyon, Simpson Park Mountains, Nev.

6, 7. Transverse and longitudinal thin sections of holotype, USNM 166482. X2l/z. Roberts
Mountains Formation. Locality M1313, Bootstrap Hill.

8—10. Australophyllum (Toquimaphyllum)johnsoni Merriam

Transverse and longitudinal thin sections of holotype, USNM 150420. X2. Great Basin

Silurian coral zone E. Locality M1114, Ikes Canyon, Toquima Range, Nev.

PROFESSIONAL PAPER 973 PLATE 6

GEOLOGICAL SURVEY

  
   
  
     

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SPONGOPHYLL UM, CARLINASTRAEA, AND A USTRAL OPHYLL UM

PLATE 7

FIGURES 1—4. Carlinastraea tuscaroraensis n. gen, n. sp.
1—3. Transverse and longitudinal thin sections of holotype, USNM 166482. X6. Roberts
Mountains Formation. Locality M1313, Bootstrap Hill, Tuscarora Mountains, Nev.
4. Longitudinal thin section. X6. Great Basin Silurian coral zone D. Roberts Mountains
Formation. Locality M1384, Coal Canyon, Simpson Park Mountains, Nev.
5, 6. Chonophyllum simpsoni Merriam
Transverse and longitudinal thin sections of holotype, USNM 159408. Xll/z. Great Basin
Silurian coral zone E. Roberts Mountains Formation. Locality M1108, Coal Canyon,
Simpson Park Mountains, Nev.
7, 8. Calostylis? sp.
Transverse thin sections. X3. Roberts Mountains Formation. Locality M1314, Bootstrap
Hill, Tuscarora Mountains, Nev.

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PROFESSIONAL PAPER 973 PLATE 7

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GEOLOGICAL SURVEY

CARLINASTRAEA, CHONOPHYLL UM, AND CALOSTYLIS ?

PLATE 8

FIGURES 1, 2. Carlinastraea sp., cf. C. tuscaroraensis, 1). gen., n. sp.
Transverse and longitudinal thin sections of same corallum. ><2. Roberts Mountains Forma-
_ tion. Locality M1409, Cortez Mountains, Eureka County, Nev.
3—7. Australophyllum (A ustralophyllum) sp. c
Locality M1318, west side of Coal Canyon in fault zone, Northern Simpson Park Moun-
tains, Nev. All the thin sections are from same corallum.
3—5. Transverse thin sections. X2.
6, 7. Longitudinal thin sections. X2.
8—11. Australophyllum (Australophyllum) sp. v
Vaughn Gulch Limestone. Mazourka Canyon, northern Inyo Mountains, Calif.
8, 9. Transverse and longitudinal thin sections of same corallum. X2. Locality M1410.
10, 11. Transverse and longitudinal thin sections of another corallum. ><2. Locality
M1093.

PROFESSIONAL PAPER 973 PLATE 8

GEOLOGICAL SURVEY

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CARLINASTRAEA AND A USTRALOPHYLL UM

PLATE 9

FIGURES 1—3. Kyphophyllum nevadensis Merriam
Great Basin Silurian coral zone E. Locality M1114, Ikes Canyon, Toquima Range, Nev.
Holotype7 USNM 159425.
1. Transverse thin section. X4.
2. Transverse thin section. X2.
3. Longitudinal thin section. X2.
4—8. Kyphophyllum sp. c
Transverse and longitudinal thin sections. Great Basin Silurian coral zone E. Locality
M1380, Coal Canyon, Simpson Park Mountains, Nev.
4, 6, 8. Transverse thin sections. X2.
5, 7. Longitudinal thin sections. X2.
9, 10. Chonophyllum simpsoni Merriam
Transverse and longitudinal thin sections of paratype, USNM 159409. X2. Great Basin
Silurian coral zone E. Roberts Mountains Formation. Locality M1108, Coal Canyon,
Simpson Park Mountains, Nev.

GEOLOGICAL SURVEY PROFESSIONAL PAPER 973 PLATE 9

 

 

 

KYPHOPHYLL UM AND CHONOPHYLL UM

FIGURES 1—3.

5—7.

9—11.

12, 13.

14—17.

18, 19.

20.

PLATE 10

Verticillopora annulata Rezak.
Roberts Mountains Formation. Locality M1411, west side of Coal Canyon, northern
Simpson Park Mountains, Nev. All figures are of the same individual.
1. Latex impression of exterior. X 1.
2. Chert filling of internal cavity. X 1.
3. Latex impression of interior. X 1.

. Verticillopora sp., cf. V. annulata Rezak.

End view showing central cavity and small radial canals to exterior. Xl/g. Roberts Moun-
tains Formation, upper part. Great Basin Silurian coral zone E. Locality M1106, east side
of Coal Canyon near mouth, northern Simpson Park Mountains, Nev.

Cladopora Sp. v.
Lateral views of pieces of branching colonies. X2.

. Digitate favositid.

Lateral View of piece of branching colony. X11/2. Vaughn Gulch Limestone, basal beds of

upper unit. Locality M1093, Mazourka Canyon, northern Inyo Mountains, Calif.
Favosites sp. c.

Transverse and two longitudinal thin sections. X2. Roberts Mountains Formation. Locality

M1411, west side of Coal Canyon, northern Simpson Park Mountains, Nev.
Favosites sp. d.

Transverse and longitudinal thin sections of form with very narrow corallites. X 2. Roberts
Mountains Formation, upper part. Great Basin Silurian coral zone E. Locality M1106,
east side of Coal Canyon near mouth, northern Simpson Park Mountains, Nev.

Kyphophyllum sp. t.

Lower part of Tor Limestone. Locality M1397, Toquima Range, Nev. All figures are of the
same corallum.

14. Transverse thin section. ><2.
15—17. Longitudinal thin sections. X2.
Ketophyllum sp. t.

Transverse and longitudinal thin sections of same corallum. X2. McMonnigal Limestone.

Locality M1393, Toquima Range, Nev.
Hercynella-like mollusk.

Lateral view. ><11/2. Near locality M1106, Coal Canyon, east side near mouth. Northern

Simpson Park Mountains, Nev.

PROFESSIONAL PAPER 973 PLATE 10

GEOLOGICAL SURVEY

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VER TICILLOPORA, CLADOPORA, FA VOSITES, KYPHOPHYLL UM, KETOPHYLL UM, AND HERCYNELLA

PLATE 1 1

FIGURES 1—6. Verticillopora annulata Rezak.
1—4. Great Basin Silurian coral zones D—E. Upper middle part of Vaughn Gulch Limestone.
Locality M1128, Mazourka Canyon, Inyo Mountains, Calif.
1. Transverse view. Xll/z.
2, 3. Transverse and lateral views of same individual. X11/2.
4. Lateral View. XII/2.
5. Lateral view. X1. Great Basin Silurian coral zones D—E. Locality M1385, Mazourka
Canyon, Inyo Mountains, Calif.
6. Transverse view. X 11/2. Great Basin Silurian coral zone D. Locality M1103, Ikes Canyon,
Toquima Range, Nev. Roberts Mountains Formation.
7, 8. Verticillopora cf. V. annulata Rezak.
Great Basin Silurian coral zone D. Roberts Mountains Formation, unit 3 near top. Locality
M1100, Roberts Creek Mountain, Nev.
7. Weathered specimen showing wall of internal cavity. X3.
8. Weathered interior showing radial canals. X2V2.
9—14. Kozlowskiellina sp. f
9—12. Great Basin Silurian coral zone D. Roberts Mountains Formation, unit 3 near top.
Locality M1100, Roberts Creek Mountain, Nev.
9, 10. Exterior and interior of same ventral valve. X2.
11, 12. Interior and exterior of same dorsal valve. X3.
13, 14. Exterior and interior of same ventral valve. X2. Great Basin silurian coral zone E.
Upper part of Roberts Mountains Formation. Locality M1106, Coal Canyon, Simpson
Park Mountains, Nev.
15—17. Homoeospira sp. r
Dorsal, ventral, and anterior views of same individual. X2. Great Basin Silurian coral zone
D. Roberts Mountains Formation, unit 3 near top. Locality M1100, Roberts Creek Moun-
tain, Nev.
18, 21, 22. Dicoelosia sp. r
Great Basin Silurian coral zone D. Roberts Mountains Formation, unit 3 near top. Locality
M1100, Roberts Creek Mountain, Nev.
18. Interior of dorsal valve. X4.
21, 22. Dorsal and ventral exterior views of same individual. X4.
19, 20. Dicoelosia sp. r.
Interior and exterior views of same ventral valve. X21/z. Great Basin Silurian coral zone D.
Roberts Mountains Formation, unit 3 near top. Locality M1100, Roberts Creek Mountain,
Nev.
23, 24. Plectatrypa? sp. 0
Dorsal and ventral exterior of same individual. X2. Great Basin Silurian coral zone E.
Locality M1106, Coal Canyon, Simpson Park Mountains, Nev.
25, 25. Gypidula sp. r.
Dorsal and ventral interior of same individuals. X2. Great Basin Silurian coral zone D.
Roberts Mountains Formation, unit 3 near top. Locality M1100, Roberts Creek Mountain,
Nev.

GEOLOGICAL SURVEY PROFESSIONAL PAPER 973 PLATE 11

 

VER TICILL OPORA, KOZL 0 WSKIELLINA , HOMEOSPIRA , DICOEL OSIA, PLECTA TR YPA ?, AND G YPID ULA

FIGURES 147.

8—15.

16, 17, 23.

18—22.

24—26.

27, 28.

2&33.

34—36.

PLATE 12

Coelospira sp. b
Roberts Mountains Formation. Locality M1412, Bootstrap Hill, southern Tuscarora Mountains.
1. Exterior view of ventral valve. X4.
2, 3. Dorsal valve and ventral valve exterior views of same shell. X4.
4. Exterior view of dorsal valve. X4.
5. Interior View of dorsal valve. X4.
6. Interior view of ventral valve. X4.
7. Interior view of dorsal valve. X4.
Fardenia sp. b
Roberts Mountains Formation. Locality M1412, Bootstrap Hill, southern Tuscarora Mountains.
8. Interior View of ventral valve. X2.
9, 10. Exterior and interior views of same dorsal valve. X2.
11, 12. Exterior and interior views of same dorsal valve. X2.
13, 14. Exterior and interior views of same dorsal valve. X2.
15. Interior view of ventral valve. X2.
Kozlowskiellina sp. b
Roberts Mountains Formation. Locality M1412, Bootstrap Hill, southern Tuscarora Mountains.
16, 17. Exterior and interior views of same ventral valve. X2.
23. Exterior view of dorsal valve. X2.
Conchidium sp. b.
Roberts Mountains Formation. Locality M1412, Bootstrap Hill area, southern Tuscarora Mountains, Nev.
18, 19. Exterior and interior views of same ventral valve. X 1.
20. Exterior view of ventral valve. X2.
21, 22. Exterior and interior views of same dorsal valve. X2.
Conchidium sp., cf. C. miinsteri Kiaer.
Type section of Roberts Mountains Formation on Pete Hanson Creek. Upper beds of unit 2. Roberts Creek Moun-
tain, Nev.
24, 25. Exterior ventral and lateral views of same ventral valve. X 1.
26. Lateral View of same shell as in figures 24 and 25 split longitudinally to show medium septum and
spondylium. X 11/2.
Cyathophylloides sp. f.
Transverse and longitudinal thin sections. X 4. Locality M1412, Bootstrap Hill area, southern Tuscarora Mountains,
Nev.
Brachyelasma sp. b.
Locality M1120, Bootstrap Hill southwest side, southern Tuscarora Mountains, Nev.
29, 30. Transverse and longitudinal thin sections of same corallum. X2.
31—32. Transverse thin sections of same corallite. X2.
33. Longitudinal thin section of corallite in figures 31 and 32. X2.
Lykophyllid rugose coral.
Locality M1413, northeast of Lynn window of R. J. Roberts, Tuscarora Mountains, northeast Eureka County.
34, 35. Transverse and longitudinal thin sections of same corallum. X2.
36. Transverse thin section. X2.

PROFESSIONAL PAPER 973 PLATE 12

GEOLOGICAL SURVEY

 

 

FARDENIA, KOZLOWSKIELLINA, CONCHIDIUM, CYA THOPHYLLOIDES,
BRACHYELASMA, AND LYCOPHYLLID

COEL OSPIRA,

 

 

 

 

 

 

 

 

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Type Sections and Stratigraphy of the
Members of the Blackleaf and Marias
River Formations (Cretaceous) of the

Sweetgrass Arch, Montana

- -_ — —

GEOLOGICAL SURVEY PROFESSIONAL PAPER 974

 

 

)CT 1 \976
roS-SoDo

Type Sections and Stratigraphy of the
Members of the Blackleaf and Marias
River Formations (Cretaceous) of the

Sweetgrass Arch, Montana

By W. A. COBBAN, C. E. ERDMANN, R. W. LEMKE, and E. K. MAUGHAN

 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 974

A report ofafieral subdivision and
age assignments ofa classic
Cretaceous area

 

 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1976

UNITED STATES DEPARTMENT OF THE INTERIOR

THOMAS S. KLEPP E, Secretary

GEOLOGICAL SURVEY

V. E. McKelvey, Director

 

Library of Congress Cataloging in Publication Data

Cobban, William Aubrey, 1916—

Type sections and stratigraphy of the members of the Blackleaf and Marias River Formations (Cretaceous) of the Sweetgrass arch,
Montana.

(Geological Survey Professional Paper 974)

Bibliography: p. 61—63.

Supt. of Docs. no.: I 19.162974

1. Geology, Stratigraphic—Cretaceous. 2. Geology, Stratigraphic—Nomenclature—Montana. l. Cobban, William Aubrey, 1916—
II. Series: United States Geological Survey Professional Paper 974.

QE687.T94 551.7'7'09786 76—608181

 

For sale by the Superintendent of Documents, US. Government Printing Olfice
Washington, DC. 20402

Stock Number 024—001—02874—3

CONTENTS

Page Page
Abstract __________________________________________________ 1 Blackleaf Formation—Continued
Introduction ________________________________________________ 2 Bootlegger Member ____________________________________ 31
Acknowledgments ______________________________________ 2 Marias River Shale ________________________________________ 36
Historical summary ____________________________________ 2 Floweree Member ______________________________________ 37
Blackleaf Formation ________________________________________ 5 Cone Member ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 40
Flood Member __________________________________________ 6 Ferdig Member ________________________________________ 44
Taft Hill Member ______________________________________ 15 Kevin Member ________________________________________ 50
Vaughn Member ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 25 References cited ____________________________________________ 61
Index ______________________________________________________ 65
ILLUSTRATIONS

Page
FIGURE 1. Index map of the Sweetgrass arch and surrounding area __________________________________________________________ 3
2. Photograph of type section of the Flood Member of the Blackleaf Formation ________________________________________ 6
3. Photograph of very large sandstone concretion in the Flood Member ________________________________________________ 9
4. Photograph of fresh-water limestone bed near the top of the Kootenai Formation ____________________________________ 10
5. Lithologic column of the type section of the Flood Member and map showing line of section ,,,,,,,,,,,,,,,,,,,,,,,,,, 11
6. Photograph of the upper part of the Taft Hill Member of the Blackleaf Formation __________________________________ 18
7. Lithologic column of the type section of the Taft Hill Member and map showing line of section ______________________ 20
8. Photograph of type section of the Vaughn Member of the Blackleaf Formation ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 26
9. Photograph of the upper part of the Vaughn Member _______________________________________________________________ 28
10. Lithologic column of the type section of the Vaughn Member and map showing line of section _______ , ________________ 29

11. Lithologic column of the type section of the Bootlegger Member of the Blackleaf Formation and map showing line of
section _____________________________________________________________________________________________________ 35
12. Photograph of the Floweree Member of the Marias River Shale at its type locality __________________________________ 38
13. Lithologic column of the type section of the Floweree Member and map showing line of section ______________________ 39
14. Photograph of the upper part of the Cone Member of the Marias River Shale at its type locality ______________________ 42
15. Lithologic column of the type section of the Cone Member and map showing line of section __________________________ 43
16. Lithologic column of the type section of the Ferdig Member of the Marias River Shale and map showing line of section 48
17. Photograph of bentonite beds in lower part of the Kevin Member of the Marias River Shale __________________________ 51
18. Photograph of the upper part of the Kevin Member overlain by the Telegraph Creek Formation ______________________ 53
19. Lithologic column of the type section of the Kevin Member and map showing line of section __________________________ 54

III

 

 

TYPE SECTIONS AND STRATIGRAPHY OF THE
MEMBERS OF THE BLACKLEAF AND MARIAS RIVER FORMATIONS
(CRETACEOUS) OF THE SWEETGRASS ARCH, MONTANA

By W. A. COBBAN, C. E. ERDMANN, R. W. LEMKE, and E. K. MAUGHAN

ABSTRACT

Rocks of Albian—Santonian age, cropping out on the Sweetgrass
arch in north-central Montana, consist of the Blackleaf Formation,
186 to 253 m (610—830 ft) thick, and the overlying Marias River
Shale, 280 to 363 m (920—1,190 ft) thick. In general, the Blackleaf
thickens southward, and the Marias River thickens westward. Each
formation has four named members.

The members of the Blackleaf Formation are, from oldest to
youngest, Flood, Taft Hill, Vaughn, and Bootlegger. Quartz
sandstone and very dark gray shale characterize the Flood Member,
which rests disconformably on green and red mudstones of the non—
marine Lower Cretaceous Kootenai Formation.

The Flood Member is 42 m (138 ft) thick in its type section, where
it consists of a basal ledge-forming thin-bedded flaggy sandstone, a
medial slope-forming dark-gray shale, and an upper thick cliff—
forming sandstone that contains huge sandstone concretions. Trace
fossils, chiefly small tracks, trails, and burrows, are abundant in the
flaggy beds and suggest a shallow—water near-shore marine envi-
ronment for most of the member. On the east flank of the Sweetgrass
arch, Inoceramus comancheanus Cragin, of late Albian age, was
found in sandstone at the top of the member. This pelecypod is
known from the Skull Creek Shale of the Black Hills area of South
Dakota, the Kiowa Shale of Kansas, and the South Platte Formation
of Colorado.

Glauconitic sandstone and medium-gray soft bentonitic silty shale
characterize the Taft Hill Member, which is 74 m (242 ft) thick in its
type section. The lower contact is gradational and the upper sharp
and disconformable. The member is divisible into three units by a
thick glauconitic sandstone separating a lower and an upper unit of
silty bentonitic shale and thin glauconitic sandstone beds. Fossils,
which are scarce in the member, include Inoceramus bellvuensis
Reeside, of late Albian age.

The Vaughn Member, 26 m (86 ft) thick in its type section, is a
nonmarine sequence of light-colored bentonitic clay, siltstone, and
sandstone that rests sharply on the marine Taft Hill Member. In
general, the Vaughn Member consists of a lower unit of pale—yellow
friable arkosic sandstone and an upper unit of bentonitic clay and
tuffaceous siltstone and minor amounts of bentonite and sandstone.
Minute crystals of a red zeolite (clinoptilolite) are so abundant in the
upper clayey unit as to impart a pinkish aspect to the outcrops. The
Vaughn Member is usually poorly vegetated and erodes into bad-
lands. Fossil logs are present in the lower sandstone unit, and a few
fossil leaves and fragments of reptilian bones occur in the upper
clayey unit.

The Bootlegger Member, a westward sandy equivalent of the
Mowry Shale, totals 100 m (329 ft) in thickness in the type section
and consists of thin beds of medium-gray very fine to fine-grained
sandstone, gray siltstone, dark-gray shale, and bentonite. The
sandstone, siltstone, and shale are usually interlaminated. At least
12 beds of bentonite are present in the type section; the two thickest

 

beds (2—3 m) contain hard lenslike masses of zeolitic tuff. Thin beds
of black-coated chert pebbles are present locally, and one, just below
the top, contains pebbles as much as 5 cm in diameter in a matrix of
coarse-grained salt—and-pepper sandstone that includes abundant
fish bones. Many of the beds of sandstone, siltstone, and shale are
hard, resulting in ledge-forming outcrops. Both contacts of the
member are sharp. The Bootlegger thins westward largely by the
lower part grading into nonmarine beds assigned to the Vaughn
Member. Over much of the Sweetgrass arch, the Bootlegger Member
is divisible into lower and upper hard sandy units separated by a
medial unit of softer shale. Fish scales and bones are common in the
upper sandy unit. Neogastroplites, an ammonite believed to be of
latest Albian and earliest Cenomanian age, has also been found in
the upper sandy unit.

The Marias River Shale consists of the Floweree, Cone, Ferdig,
and Kevin Members. The Floweree Member unconformably overlies
the Bootlegger Member and is 19.4 m (63.5 ft) thick at its type
section. It consists chiefly of a sequence of dark-bluish-gray shale,
lighter gray sandy shale, and thin beds of siltstone and sandstone.
Thin layers of chert granules or small pebbles are present locally.
Gray septarian limestone concretions occur on the east flank of the
Sweetgrass arch. The Floweree Member is softer and darker than the
underlying Bootlegger Member. Trace fossils, consisting of small
tracks, trails, and burrows, are common on the sandstone and
siltstone layers. These sandy beds have also yielded a few impres-
sions of inoceramids and ammonites, including M etoicoceras muelleri
Cobban and M. mosbyense Cobban, of late Cenomanian age. A
slightly older late Cenomanian ammonite, Calycoceras
canitaurinum (Haas), was found in one of the septarian limestone
concretions. These fossils occur in the lower half of the Greenhorn
Formation of the Black Hills area.

The Cone Member is a thin calcareous unit of latest Cenomanian
and earliest Turonian age. A rather uniform thickness of 15—18 m
(50—60 ft) is consistent over most of the Sweetgrass arch. Most of the
member is dark-gray calcareous shale that weathers light bluish
gray first and then yellowish white. The upper half of the member,
and especially the uppermost part, contains thin beds of argillaceous
or crystalline limestone that tend to form low ridges. Septarian lime-
stone concretions occur at several horizons; the most conspicuous bed
is just above the base and contains closely spaced concretions that
weather pale lavender gray. Several beds of bentonite are present,
and one, at the top of the lower third of the member, attains a thick-
ness of nearly a metre. The contacts of the member are sharp and
marked by an abrupt change from the limy shale of the Cone to the
noncalcareous shale of the underlying Floweree and overlying Fer-
dig Members. A thin layer of limonitic siltstone at the base, contain-
ing shale pebbles, soft white siltstone nodules, and fish teeth and
bones, probably marks a disconformity. Invertebrate fossils are
abundant and reveal the zones of Sciponoceras gracile (Shumard)

1

2 BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

and Inoceramus labiatus (Schlotheim) which are found in the upper
part of the Greenhorn Formation of the Black Hills area.

The Ferdig Member, 68.6 m (224 ft) thick in its type section, is a
sequence of gray noncalcareous shale containing thin hard sandy
partings and gray- to yellow—weathering limestone concretions and
dusky-red-weathering dolostone concretions. Three units make up
the member—a lower dark-bluish—gray sandy shale containing gray-
and yellow-weathering calcareous concretions, and an upper dark-
bluish-gray shale containing gray-weathering calcareous concre-
tions. Thin beds of bentonite are sparingly present. A very thin, but
persistent, layer of conglomeratic sandstone in the upper part of the
member contains polished granules and small pebbles of black, gray,
brown, and green chert, as well as pebbles of quartz, quartzite, and
argillite. The contact of the Ferdig with the underlying Cone
Member is sharp and disconformable; it is marked by a thin layer of
limonitic siltstone containing, in places, fish teeth, small pebbles of
black chert, and larger gray and brown phosphatic pebbles. In well
cuttings, the shale in the upper part of the Ferdig may show finely
disseminated pyrite. The contact with the overlying Kevin Member
is conformable. Molluscan fossils are common and reveal at least
three zones. Prionocyclus hyatti (Stanton), of middle Turonian age, is
found in the lower unit, characterized by dusky-red dolostone concre-
tions. Scaphites nigricollensis Cobban, of middle late Turonian age, is
present through much of the medial sandy unit. Scaphites corvensis
Cobban, of slightly later Turonian age, occurs at the top of the sandy
unit and in the overlying upper shale unit.

The Kevin Member, 188 m (617 ft) thick in its type section, is a
dark-gray shale that contains some thin sandy parts, numerous thin
layers of bentonite, and many beds of calcareous concretions that
weather gray, yellow, or dusky red. The member is divisible into
three units on the basis of abundance of bentonite beds and composi—
tion of concretions. Numerous beds of bentonite and gray- to
yellow-weathering limestone concretions characterize the lowest
unit, which is 53—55 m (175»180 ft) thick. The many thin layers of
light—gray bentonite give the outcrop a distinctive banded appear-
ance. The medial unit, about 60 m (200 ft) thick, contains numerous
beds of orange— to dusky—red-weathering ferrocalcareous concretions
and a few thin layers of bentonite and very fine grained sandstone.
An important marker bed, the MacGowan Concretionary Bed, lies in
the middle of this unit. The MacGowan Bed is a conglomeratic bed of
concretionary dolostone that weathers light brown, orange brown,
and dusky red, and contains polished granules and small pebbles of
gray and black chert and larger pebbles of gray phosphatic siltstone.
One or two thin layers of greenish-gray phosphatic pebbles are pre-
sent in the medial unit in the interval 8~10 m above the MacGowan
Bed. The upper unit of the Kevin Member consists of about 60 m
(200 ft) of dark-gray shale that contains many beds of yellowish-
gray-weathering limestone concretions and a few thin beds of bento-
nite and very fine grained shaly sandstone. The upper half of this
unit is in part calcareous. The boundary between the Kevin Member
and the overlying Telegraph Creek Formation is sharp but conform-
able; it is marked by a change from the dark—gray shale of the Kevin
Member to the lighter gray shale and siltstone of the Telegraph
Creek Formation, interlaminated with very fine grained sandstone.
Molluscan fossils are abundant and varied in the Kevin Member.
The lower unit, ofearly Coniacian age, contains a zone ofInoceramus
erectus Meek below and a zone of Inoceramus deformis Meek above
and is correlated with the Fort Hays Limestone Member of the Nio-
brara Formation of the central Great Plains. The middle unit,
characterized by the red-weathering ferrocalcareous concretions,
contains three faunal zones; from oldest to youngest, a zone of I n—
oceramus (Voluiceramus) involutus Sowerby—Scaphites ventricosus
Meek and Hayden of Coniacian age, a zone oflnoceramus stantoni
Sokolow~Scaphites depressus Reeside of early Santonian age, and a
zone of I noceramus cordiformis Sowerby—Clioscaphites vermiformis

 

(Meek and Hayden) of middle Santonian age. The upper unit con-
tains the rest of the C. vermiformis zone and the younger Santonian
zones of C. choteauensis Cobban and Desmoscuphites erdmanni
Cobban.

INTRODUCTION

Rocks formerly assigned to the Colorado Shale
(Fisher, 1909, p. 36) on the Sweetgrass arch of north-
central Montana (fig. 1) are divided in this paper into
an older Blackleaf Formation and a younger Marias
River Shale, both formations of the Colorado Group.
The Blackleaf Formation is assigned to the Lower Cre-
taceous and is subdivided into four members, from old-
est to youngest: Flood Member, Taft Hill Member,
Vaughn Member, and Bootlegger Member. The Marias
River Shale, of Late Cretaceous age, is subdivided also
into four units, from oldest to youngest: Floweree
Member, Cone Member, Ferdig Member, and Kevin
Member. Although these formations and members
have been previously defined by the authors (Cobban
and others, 1959), type sections, fossil lists, and the
regional stratigraphy were not presented. The purpose
of the present report is to complete this presentation.

ACKNOWLEDGMENTS

Other geologists with the US. Geological Survey
who have aided in the measurement of some of the
sections on the Kevin-Sunburst dome are B. R. Alto,
A. F. Bateman, and W. L. Rohrer. Geologists, formerly
with the US. Geological Survey, who have partici-
pated in the study of the Colorado Shale on the
Kevin-Sunburst dome are V. K. Koskinen, J. W.
Nordquist, J. T. Gist, G. W. Beer, and K. H. Holmes.

HISTORICAL SUMMARY

The earliest investigation of the rocks later assigned
to the Colorado Group in Montana was undertaken in
18‘61 by Meek and Hayden, who gave the name “Fort
Benton Group, Formation No. 2” to the “Dark gray
laminated clays, sometimes alternating near the upper
part with seams and layers of soft gray and light-
colored limestone. Inoceramus problematicus, I. ten—
uirostratus, I. latus?, I. fragilis, Ostrea congesta, Ven-
ilia Mortoni, Pholadomya papyracea, Ammonites Mul-
lani, A. percarinatus, A. vespertinus, Scaphites war—
reni,‘ S. larvaeformis, S. ventricosus, S. vermiformis,
Nautilus elegans? etc. Extensively developed near Fort
Benton 0n the Upper Missouri” (Meek and Hayden,
1861, p. 419). Of these fossils, Inoceramus tenuiros-
tratus, Veniella mortoni (as Venilia Mortoui),
Pholadomya papyracea, Scaphites ventricosus, Clio—
scaphites vermiformis (as Scaphites vermiformis), and
Cymatoceras nebrascense (as Nautilus elegans?) came
from “Chippewa Point*** some twenty odd miles below

INTRODUCTION 3

L B E A
BORDER-RED COULEE
_ _ _I

. 4 4,,

y’asls

3

,6 AC 1 E R
"\-.-\ 33

x
N A T I o N A L - ;
INDIAN y RESER TION

D

Dupuyer

EXPLANATION

Blackleaf or Marias River
Formation

M-

Oil field Gas field

Ei]

Area covered by US.

Geological Survey

topographic quadrangle
II] Marius Puss IEI Dent Bridge IEI Cascade
IE Heart Butte Fairfield IE] Carter

 

 

E Sunburst Vaughn @ Tunis A
El Shelby E] Great Falls Lander Crossing
, WolfCreek
E] Dutton Portage [El Valier
‘ 5 4
o 10 20 30 40 50 MILES
L I I I I I
I I I I I I I I j
o 10 20 30 4o 50 60 7o 80 KILOMETRES

FIGURE 1.——Sweetgrass arch and surrounding area.

Fort Benton” (Meek and Hayden, 1862, p. 21—28. Those the Niobrara River in Nebraska. Thus, inadvertently
fossils are now known to be of Niobrara age. Meek and they included rocks of Niobrara age in the Benton
Hayden did not know that their chalky “Niobrara Di- Group which later was reduced to formation rank, the
Vision, Formation No. 3” underwent a facies change Benton Shale, and restricted to beds of Graneros,
northwestward from its type locality at the mouth of Greenhorn, and Carlile age.

4 BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

Weed (1899, p. 2) applied the name Colorado For-
mation to the following highly generalized 565-m
(1,850—ft) sequence on the southeastern part of the
Sweetgrass arch, whose descriptive text has been
taken from the columnar section sheet of the Fort Ben-
ton Folio:

Top

“Drab or lead-colored clay shale, carrying round or
oval concretions of gray limestone.

Black shale with interbedded sandstones and a
bed of tuff.

Red shale and sandstones in thin beds.

Lilac-colored sandstone, red clay, and thin lime-
stone.”

This formation rested on Weed’s Dakota Formation,
a sequence of “Red shale with limestone nodules
capped by sandstone, and sandstone at the base.” Over-
lying the Colorado Formation was a sandstone to
which Weed gave the name Eagle Formation. The
lower part of this unit probably includes the Telegraph
Creek Formation, the basal formation of the Montana
Group.

Willis (1902, p. 315, 326, 327), in describing the
geology of what is now Glacier National Park, used the
name Benton Shale for the uppermost or “lead-colored
clay shale” member of Weed’s Colorado Formation and
the name Dakota Sandstone for the next-to-the-top
unit. Willis listed several plant fossils from his Dakota
Sandstone and a dozen marine molluscan genera from
his Benton Shale. ‘

The geology of the Great Falls coal field, south and
southeast of Great Falls, was described by Fisher
briefly in 1907 and in much more detail in 1909. He
applied the term Colorado Shale to the upper two units
(black and gray shales and interbedded sandstones) of
Weed’s Colorado Formation. The lower two units (red),
as well as Weed’s Dakota Formation, were assigned to
the Kootenai Formation. The thickness of the strata
referred to the Colorado Shale was therefore reduced to
about 463 m (1,520 ft). Regarding the boundaries,
Fisher (1909, p. 38) stated: “The Colorado shale rests
with apparent conformity upon the underlying
Kootenai, and is overlain conformably by the Eagle
sandstone.” Fisher (1907, p. 163; 1909, p. 37) gave a
generalized section through the lower or sandy part of
the Colorado Shale at Belt Butte.

Stanton (1913) extended the terms Colorado Shale
and Eagle Sandstone into the Blackfeet Indian Reser-
vation west of the crest of the Sweetgrass arch. In the
following year, Stebinger (1914) used the name Vir-
gelle in place of Eagle, inasmuch as the sandstone in
the reservation represented only the lower or Virgelle
Sandstone Member of the Eagle Sandstone. Stebinger
(1914, p. 62) pointed out that the Virgelle Sandstone

 

Member was massive in the upper part, whereas the
lower half was "slabby"‘*"< becoming shaly toward the
base.” A little later, Stebinger (1916, p. 124; 1917,
p. 285, 287, 289) applied the name Colorado Shale as
far west as Glacier National Park, where the formation
then included Willis’ Dakota Sandstone and Benton
Shale.

In the course of mapping the Disturbed belt along
the Rocky Mountain front between Sun River and
Birch Creek (southern boundary of Blackfeet Indian
Reservation), Stebinger (1918, p. 154, 158—161) divided
the Colorado Shale into a lower member, the Blackleaf
Sandy Member, 183—213 111 (600—700 ft) thick and an
upper shale member 365 m (1,200 ft) thick. A gener-
alized columnar section (Stebinger, 1918, p. 158) was
given for the Blackleaf Sandy Member and basal part
of the overlying shale member. The stratigraphic posi-
tions of five fossil collections were shown and the fos-
sils listed (Stebinger, 1918, p. 160). Beginning about 24
m (80 ft) above the top of the Blackleaf, Stebinger re-
corded a “bituminous shale and maltha limestone” se-
quence, about 18 m (60 ft) thick, which contained
abundant I noceramus labiatus (Schlotheim). This unit
had been noted earlier by Powers and Shimer (1914, p.
557), who noted “dark arenaceous shale” with abun-
dant Inoceramus labiatus (Schlotheim) and Lingula sp.
near the Sun River. Stebinger used the name Virgelle
for the sandstone overlying the Colorado Shale and
placed the boundary between the two formations “at
the position where the amount of sandstone exceeds
that of the shale in the transition beds.”

Romine (1929, p. 786—788) brought Stebinger’s name
Blackleaf to the Sweetgrass arch. Collier (1929 [1930],
p. 70—72) presented a generalized section of the
member in the area a few miles north of Vaughn and
listed 39 species of invertebrate fossils, identified by J.
B. Reeside, Jr., from 17 localities on the Sweetgrass
arch. The stratigraphic positions of the fossils were
given in feet below the top of the Colorado Shale. Also,
Dobbin and Erdmann (1930) used several sandstone
units of the Blackleaf Sandy Member in structural
mapping on the Sweetgrass arch.

Before 1939, the boundary between the Colorado
Shale and the Virgelle Sandstone was placed either
within the sandy transition beds (Stebinger, 1918, p.
164, 165) or at the top of the transition beds (Dobbin
and Erdmann, 1930). Erdmann and Davis (1939)
treated the transition beds as a separate formation des-
ignated "transition zone.” Later (Erdmann and
Schwabrow, 1941, p. 280—282; Blixt, 1941, p. 334, 335),
the transition zone was considered as the lower
member of the Eagle Sandstone. Erdmann (1948)
applied the name Telegraph Creek(?) Formation to the
transition beds. Later, Cobban (1950) was able to re-

BLACKLEAF

move the query by listing fossils of Telegraph Creek
age from the formation.

The upper part of the Colorado Shale on the Kevin-
Sunburst dome was divided into two formations, Car-
lile and Niobrara, by Erdmann, Gist, Nordquist, and
Beer (1947). A detailed columnar section of the Nio-
brara Formation was presented. The stratigraphic pos-
itions of key marker beds (lettered A through M) were
indicated from near the top of the formation down-
ward. Bed “F,” near the middle of the Niobrara Forma-
tion, was described as a persistent and easily identified
mud pellet conglomerate (later identified as con-
glomeratic phosphorite) that weathers orange buff and
contains some chert pebbles. Bed "N,” a thin hard layer
of gray sandstone that contains gray and black chert
pebbles, was used as the top of the Carlile Formation of
Erdmann, Gist, Nordquist, and Beer (1947). In a later
report by Erdmann (1949), on the Lothair area just
southeast of the Kevin-Sunburst dome, the term Col-
orado Shale was used again.

Cobban (1951a) showed that the Colorado Shale on
the Sweetgrass arch was divisible into many distinc-
tive lithologic units that could be correlated by their
fossil content and, in places, by their lithologic features
with the formations and members of the Colorado
Group of the Black Hills area of South Dakota. Most of
the guide fossils were figured (Cobban, 1951b, 1955b).
More recent refinements in correlation have been
made possible by new fossil discoveries (Cobban and
others, 1956, 1958).

Cobban, Erdmann, Lemke, and Maughan (1959), in
recognition of a need for a more precise nomenclature
in connection with geologic mapping on the Sweetgrass
arch, divided the Colorado Group into an older Black-
leaf Formation and a younger Marias River Shale. The
Blackleaf Formation was assigned to the Early Cre-
taceous and divided into four members, from oldest to
youngest: Flood Member, Taft Hill Glauconitic
Member, Vaughn Bentonitic Member, and Bootlegger
Member. The Marias River Shale was divided into four
members, from oldest to youngest: Floweree Member,
Cone Calcareous Member, Ferdig Shale Member, and
Kevin Shale Member.

Aside from Stebinger’s work (1918) in the Sun
River—Birch Creek area, little had been published con-
cerning the Colorado Shale in the Disturbed belt along
the Rocky Mountains front until fairly recently. Some
of the Cretaceous outcrops along the south side of
Glacier National Park were identified by their fossil
content and lithologic characteristics by Cobban
(1956). Schmidt (1963, 1966), in his studies of the
Dearborn River area, and Mudge (1965), in his studies
of the Sun River area, applied the nomenclature of
Cobban, Erdmann, Lemke, and Maughan (1959) ex-

 

FORMATION 5

cept for dropping the adjectival part of the name for the
Taft Hill and Vaughn Members. Fox and Groff (1966)
and Fox (1966) also applied the nomenclature of Cob-
ban, Erdmann, Lemke, and Maughan (1959) but
dropped the adjectival parts of all member names. In
order to be consistent, all adjectival terms are also
eliminated in the present study. One other important
work is that by Cannon (1966), who presented much
information concerning the lithology, thickness, paleo—
current patterns, and genesis of the members of the
Blackleaf Formation.

BLACKLEAF FORMATION

In defining his Blackleaf Sandy Member, Stebinger
(1918, p. 158) stated:
The lower 600 to 700 feet of the Colorado shale comprises an alterna-
tion of dark marine shales and gray sandstone in beds 20 to 75 feet
thick, forming a unit clearly distinguishable from the remaining
shaly portion of the Colorado. For convenience in reference and de-
scription it is here designated the Blackleaf sandy member, the
name being taken from Blackleaf Creek, along which the beds are
well developed.

The exposures on Blackleaf Creek are in the Dis-
turbed belt along the Rocky Mountains front, about
6—11 km (4—7 mi) west of Blackleaf in western Teton
County (Heart Butte quadrangle). With the exception
of a small area near the south edge of his map, Stebin-
ger included the Blackleaf with the Lower Cretaceous
and Jurassic rocks as an undifferentiated cartographic
unit.

Without referring to any specific locality, Stebinger
(1918, p. 158, fig. 33) presented for his Blackleaf only a
generalized columnar section in which the base of his
member was “bluish-gray shale” and the top was
"coarse gray sandstone.” Reference to his geologic map
(pl. xxiv), however, indicates that the locality probably
is about 43 km (27 mi) northwest of Choteau, in sec. 18,
T. 26 N., R. 8 W., andisec. 13, T. 26 N., R. 9 W., Teton
County. Notation of several fossil collections on the
column from various places in the Disturbed belt
seems to imply that the column might be composite,
but evidently these collections were inserted to show
the horizons at which fossils were found. In addition to
the Blackleaf, the columnar section shows two overly-
ing units of shale, the lower about 24 m (80 ft) thick
with a 0.15—m (6—in.) pebble bed about 9 m (30 ft)
above the base, and the upper about 24 m (80 ft) thick,
which consist of “bituminous shale” and “maltha lime-
stone.” Stebinger noted an abundance of the pelecypod
Inoceramus labiatus (Schlotheim) in the bituminous
unit..This unit, on the Sweetgrass arch, is the Cone
Member of the Marias River Shale. In north-central
Montana, the contact of this calcareous unit with the
overlying noncalcareous shale is very sharp and is

6 BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

readily determined in well cuttings and on electric
logs. This is the contact that is commonly used infor-
mally as the top of the Blackleaf by most of the pe-
troleum geologists and scouts and to some extent for-
mally in the literature (Collier, 1929, p. 70; Erdmann
and Davis, 1939; Blixt, 1941, p. 337).

The Blackleaf Formation is recognized in the area
between the Missouri River and the international
boundary and between the Rocky Mountains front and
about the longitude of Fort Benton. (See fig. 1.) To
some extent, the name has been used in southern Al-
berta adjacent to the Montana boundary (Russell and
Landes, 1940, p. 24, 25).

Throughout this area, the Blackleaf rests sharply on
the Kootenai Formation of continental origin. At any
one locality a disconformity is not apparent, but re-
gional studies suggest a hiatus and that the Blackleaf
was deposited on an uneven surface with a relief possi-
bly amounting to about 30 m (100 ft). The basal metre
of the Blackleaf has the appearance of having been
reworked from the upper part of the Kootenai by the
earliest transgression of the Lower Cretaceous sea.
This initial advance may have been comparatively
rapid, for there is no evidence that marine life had time
to become established.

FLOOD MEMBER
NAME AND DEFINITION

The Flood Member, the lowest member of the
Blackleaf Formation, is a transgressive-regressive ma-
rine unit that marks the earliest appearance of the
Lower Cretaceous sea. The unit isthe black-gray shale
and quartz sandstone member of Cobban (1951a,
p. 2175—2176).

The Flood was named formally by us (Cobban and
others, 1959, p. 2787) for exposures along the bluffs on
the west bank of the Missouri River valley in the vicin-
ity of Flood, a siding on the Burlington Northern Rail-
way in the NWM; sec. 34, T. 20 N., R. 3 E., Cascade
County, Mont., 8 km (5 mi) southwest of the City of
Great Falls. The type section is about 8 km northwest
of Flood on the south bank of Sun River in a shallow
reentrant (fig. 2) in the bluffs in the NW cor. NEIA sec.
7, T. 20 N., R. 3 E., about 7.2 km (4.5 mi) west of Great
Falls (fig. 2A). Most of the measurements were made
on the west wall of the reentrant, but the upper 6 In (20
ft) of the middle unit is better exposed across the reen-
trant to the southeast and was mostly measured there.
For descriptive purposes, the type section was sub-
divided into three units (lower, middle, and upper).

Since the construction in 1959 of a stretch of U.S.
Interstate Highway 15 between Great Falls and the
village of Vaughn, two easily accessible and more or

 

 

FIGURE 2,—Type section of the Flood Member in the NE‘A sec. 7, T.
20 N., R. 3 E., Cascade County, Mont. The threefold subdivision is
well shown. Man, holding 4.3-m (14-ft) rod, is standing on top of
lowest subdivision.

less completely exposed composite sections of the Flood
Member have been studied and described from cuts
and natural outcrops on the north side of the highway,
each about 2.4 km (1.5 mi) north of the type section,
between the vicinity of Emerson Junction and the
Manchester Exit. One section, about 4.8 km (3 mi) west
of Great Falls, in the SW%SE% sec. 32, T. 21 N., R. 3
E., and hereafter referred to as the "reference section,”
exposes the Flood Member nearly continuously from
top to bottom. The second section, about 6.4 km (4 mi)
west of Great Falls in the center NWIASEMi sec. 31, T.
21 N., R. 3 E., exposes completely the upper 11.9 m (39
ft) of the Kootenai Formation, approximately the lower
half of the Flood Member, and discontinuously exposes
the remaining part of the member. The Flood Member
is also completely exposed about 4 km (2.5 mi) south-
east of the type section in a composite section along
Gore Hill in the NE% sec. 21, T. 20 N., R. 3 E. These
three sections supplement one another nicely and, to-
gether with the type section, reveal the character of
the member in full.

THICKNESS
On the South arch of the Sweetgrass arch, the Flood
Member ranges in thickness from 26 to 60 m (85 to
197 ft). At its type section the member is 42 m (138 ft)
thick; it is 36.5 m (120 ft) thick in the reference section,

2.4 km (1.5 mi) northeast across Sun River valley.
From this vicinity the member thins northeastward to

FLOOD MEMBER 7

29.6 m (97 ft) along the Missouri River, 25.7 km (16 mi)
northeast of Great Falls, and to 25.9 In (85 ft) on Belt
Creek, 32 km (20 mi) east of Great Falls. Westward
from the axis of the Sweetgrass arch, the Flood
Member thickens as it approaches its source area. Fox
(1966, p. 61—63) measured a total thickness of 60 m
(197 ft) on the southwestern flank of the Sweetgrass
arch. Along Sun River near the Rocky Mountain front,
the member attains thicknesses of 457—1676 In (150—
550 ft) (Mudge, 1972, p. A6). Near Drummond, in T. 11
N., R. 12 W., Missoula County, about 169 km
(105 mi) southwest of Great Falls, Gwinn (1961) re-
ported thicknesses of 207—213 In (680—700 ft). Along
the route of the Burlington Northern Railway 6.4 km
(4 mi) southwest of East Glacier, the Flood Member is
at least 68.6 m (225 ft) thick.

Well cuttings from the South arch indicate thickness—
es of 15—46 m (50—150 ft), whereas cuttings from the
northern part of the Sweetgrass arch reveal thickness-
es of 15—30 111 (50—100 ft). Reasons for these thickness
variations, particularly local ones, are not well under-
stood; they may be due to erosional relief on the under-
lying Kootenai Formation, or they may be due to
channeling or scour between or within the units of the
Flood Member.

()L'TCROI’ DISTRIBL‘TION

On the Sweetgrass arch, the Flood Member crops out
only across the southern part of the South arch. The
thick sandstone at the top forms conspicuous bluffs
along the Sun River from Great Falls westward for
several kilometres, along the west side of the Missouri
River valley between Great Falls and Flood, along both
banks of the Missouri River valley between Flood and
Ulm, and on both banks of the Smith River from Ulm
southward for many kilometres. The member is ex-
posed at many places in the southern and eastern parts
of the Portage quadrangle northeast of Great Falls and
in the Belt Creek valley 24—29 km (15—18 mi) east of
Great Falls.

The Flood Member also is present in the Disturbed
belt along the Rocky Mountain front, from Glacier Na-
tional Park southeastward to Wolf Creek, where the
thick sandstone at the top of the member forms promi-
nent hogbacks wherever well exposed. Cobban (1956,
p. 1001, 1002) has drawn attention to easily accessible
outcrops along the US. Highway 2 and the Burlington
Northern Railway south of the village of East Glacier,
although recent highway construction has invalidated
mileage details of his road log.

(iliNliRAl. DESCRIPTION

The strata of the Flood Member at the type section
and in the vicinity can be separated into three individ-

 

ually distinctive lithologic units (fig. 2): (1) an incon-
spicuous lower unit of sandstone and siltstone, which
constitutes about 16 percent of the total; (2) a middle
unit of soft dark-gray somewhat carbonaceous shale,
which is usually concealed in slopes and constitutes
about 36 percent; and (3) an upper unit of cliff-making
sandstone, which accounts for the remaining 48 per-
cent.

The three lithologic units are herewith described in
a general way. Further details are given in the type
section and in other nearby sections.

Lower unit—The boundary of the lower unit with
the underlying Kootenai Formation appears to be dis-
conformable. The upper part of the Kootenai in this
area consists for the most part of beds of olive—gray
siltstone, red to maroon mudstone, olive graywacke,
and yellowish-gray sandstone of continental origin.
The basal 1.5—2.4 In (5—8 ft) of the lower unit of the
Flood Member has the appearance of having been re-
worked from this part of the Kootenai by the earliest
transgression of the Lower Cretaceous sea. Thus, even
at close distance, the boundary between the Kootenai
Formation and the lower unit of the Flood Member
may be indistinct, and the distinction between the
lower unit and the Kootenai is not as simple as farther
east, where the uppermost Kootenai strata are dusky
red. Locally, the distinction between the Kootenai and
the lower unit of the Flood is based on more uniform
bedding and better development of fissility in the shale
of the lower unit of the Flood and of better sorting in
the sandstones, the prevalence of a grayish tone that
increases in intensity upward from the boundary with
continued mixing in of normal sediment from land,
considerably less elastic mica in the sandstones, the
absence of graywacke, and the appearance of thin
laminae of reworked carbonaceous shale or coal in the
siltstone. Moreover, the olive-gray beds here assigned
to the Flood Member do not contain the freshwater
“gastropod” limestone that is diagnostic of the upper
part of the Kootenai Formation along the mountain
front to the west.

The lower unit at the Flood type section and at other
nearby exposures consists of about 6.7 m (22 ft) of
shale, siltstone, and sandstone. Approximately the
basal 1.5 m consists of soft olive-gray siltstone and fis-
sile gray silty shale. This basal section commonly is
overlain by a few feet of olive-gray siltstone with short
irregular laminae of reworked carbonaceous debris
and local thin films of coal. Layers of fine-grained
quartz sandstone, less than 0.3 m thick, make resistant
ledges in the siltstone. Approximately the upper 4.3 m
(14 ft) of the unit at the type section consists mostly of
a light—gray silty to fine-grained generally noncalcare-
ous sandstone that forms a ragged cliffy outcrop. The

8 BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

sandstone, which occurs as uneven lenticular layers
13—51 cm (0.5—20 in.) thick, is separated by films of
dark—gray shale or gray siltstone. In places it shows
ripple marks and a “torrential” or planar type of
crossbedding that dips southwest. Nearly every bed-
ding plane between the sandstone and shale or silt-
stone exhibits casts of trace fossils (trail grooves?) and
narrow elongate trains of sand that possibly were left
as alimentary waste of marine worms (Mudge, 1972,
fig. 31). Northeastward from the type section, the
sandstone tends to thin and be replaced by shale. In the
eastern part of the Portage quadrangle, only a few thin
lenses of sandstone persist in this part of the Flood
Member.

Middle unit.—This unit of the Flood Member con-
sists mostly of medium-dark-gray shale about 15 m
(50 ft) thick that rests rather sharply but conformably
on the lower unit and probably represents the culmina-
tion of the first transgression of the Lower Cretaceous
sea. The unit is largely concealed by colluvium and
talus in the type section but is fairly well exposed in
the reference section approximately 0.8 km (0.5 mi)
north of Emerson Junction (west of Great Falls in the
NE1/4 sec. 5, T. 20 N., R. 3 E.) and in several exposures
along Gore Hill, southeast of the type section (fig. 3).
The basal 6 m (20 ft) of the unit includes several
sandstone and siltstone beds up to about 0.6 m (2 ft)
thick. Some siltstone beds contain abundant worm(?)
castings or burrows. Sparingly present in lenticular
sandstones representing some kind of channel fill are
concretionary masses of compact olive-gray (brown-
weathering) dolostone as well as a scattering of spheri-
cal concretions of marcasite. The shallow channels in
which the concretions are found probably are of cur-
rent origin and may have a general eastward trend.
The middle 6 m (20 ft) of the unit consists chiefly of
gray shale that is darker, more firm, and more fissile
than most of the shale in the Blackleaf Formation. A
0.6-m (2-ft)-thick bed of grayish-black papery shale at
the base of this middle part is so highly carbonaceous
that its weathered surface resembles coal bloom. Ap-
proximately the upper 3 m (10 ft) of the unit consists
chiefly of nodular sandstone with thin laminae and
interbeds of dark-gray fissile shale, and it possibly rep-
resents the final stillstand of the first marine trans-
gression. For want of an easily recognizable boundary,
the top of the middle unit has been placed arbitrarily
on a 13-cm-thick bed of gray silty limestone having
cone-in-cone structure that overlies a 0.5-m (1.7-ft)-
thick bed of calcareous siltstone containing small dark
chert pebbles and granules.

Upper unit.—A conspicuous cliff-forming sandstone
about 20 m (66 ft) thick at the type section constitutes
the upper unit (fig. 2). Essentially the entire unit is

 

exposed at the type section. More limited outcrops
occur in bluffs along the Sun River valley to about 16
km (10 mi) west of Great Falls, where the west dip of
the Sweetgrass arch carries it under the bed of the
river in the SW14 sec. 32, T. 21 N., R. 2 E. Closely
related exposures occur in highway cuts west of Great
Falls along the north valley wall of the Sun River,
where in places the boundary between the Flood
Member and the overlying Taft Hill Member is well
revealed.

Approximately the lower 4.6 m (15 ft) of the unit at
the type section consists of light-gray poorly sorted
homogeneous siltstone and silty fine—grained sand-
stone that has a chunky or massive appearance and
that weathers yellowish gray. Small amounts of fine
carbonaceousmaterial is locally intermixed. The sand-
stone is friable, noncalcareous, and erodes easily to
slightly undercut the overstanding cliff. Thus, expo-
sures are uncommon because of concealment by collu—
vium and talus. Small granules of dark chert are pres-
ent in the basal bed. Trace fossils are common on the
undersides of two persistent fine-grained sandstone
beds that form narrow resistant ledges. This is the last
appearance of these enigmatic forms in the Flood
Member and probably results from the lack of fine mud
that constituted their environment as the sea became
shallower and there was greater depositional energy.

Approximately the middle 10.6 m (35 ft) of the unit
is the principal cliff-making part of the Flood Member.
It consists of a fairly homogeneous firm noncalcareous
fine-grained sandstone with individual beds, 0.9—4 m
(3—13 ft) thick, of slightly different hardness and tex-
ture. It is light gray to very light olive gray where
fresh and various shades of grayish and yellowish
orange where weathered. Sorting is moderate and
suggests incomplete reworking of fluvial sand in an
infralittoral (subbeach) environment. Subangular
grains of clear quartz predominate, but some beds con-
tain as much as 10 percent chert. Small spherical con-
cretions of marcasite are accessory. Clay galls occur in
some upper beds. Porosity is good. Trace fossils are
absent, and no other fossils have been found in either
the type section or nearby sections.

The upper part of the unit varies considerably in
thickness and lithology within short distances of the
type section and appears to rest on an erosion surface.
Thicknesses range from 3 to 8 m (10 to 27 ft). At least
five different lithologies are present. More or less in
order of deposition, they are (1) intraformational con-
glomerate with lumps of ferruginous sandstone, (2)
sandstone similar to that in the middle part of the unit
(most abundant lithology but not present at every 10-
cality), (3) medium- to coarse-grained crossbedded
sandstone, finely conglomeratic, with chert granules,

FLOOD MEMBER 9

(4) dark-gray carbonaceous shale, in places with inter-
beds of olive cherty sandstone, and (5) huge concretions
of hard, resistant, calcareous sandstone. Of these five
lithologies, the huge brown-weathering sandstone con-
cretions of group 5 constitute the most conspicuous
element of this part of the unit. Two horizons of concre-
tions are present, the stratigraphic interval between
their respective tops ranging from 3.7 to 5.5 m (12 to 18
ft). The concretions in both horizons are similar in ap-
pearance. Generally, they occur as Widely separated
discrete masses, but, where abundant, they nearly co-
alesce into a continuous layer. They commonly range
from simple tabular forms 2.7 by 2.7 by 0.3 m thick to
huge paraelliptical masses 6.4 by 5.5 by 3 m thick
(fig. 3). Some occupy channels. Internal structure gen-
erally is massive, but in places it is rudely concentric.
Some of the crossbedded sandstone of group 3 alter-
nates and interfingers with the marine sandstone of
2 in typical scour-and-fill arrangement. These
sandstones may have been formed in a deltaic envi-
ronment with distributary streams or in a barrier bar
island environment. If these sandstones are upper del-
taic deposits, it presupposes that the sea had all but
disappeared either by infilling or by withdrawal to-
ward the east, thus recording a regression of the Lower
Cretaceous sea from the southern part of the Sweet—
grass arch. The only fossils found in this part of the
unit were bits of wood and a small fragment of a rib
bone. The top of the unit, which is the Flood—Taft Hill
boundary, is marked in places by a disconformity of
small-time value where marine shale rest on thin
cherty crossbedded sandstone.

CHARACTER ()1: H.001) MEMBER IN THE NOR’I‘HERN
S\\'l-Il{T(}R.v\SS ARCH AND DlSTl‘RBl‘ZI) BELT

A threefold division of the Flood Member suggestive
of that shown by the outcrops in the vicinity of Great
Falls can be noted in the subsurface in numerous tests
for oil and gas along the crest of the Sweetgrass arch.
For example, in the central part of the Kevin-Sunburst
dome, T. 34 N., R. 1 W., 121—129 km (75—80 mi) north
of Sun River, the Flood Member is about 30 m thick
and consists of three units of sandstone separated by
two shale units. In all probability they are paracon-
temporaneous homotaxial equivalents of some of the
units of the type section, but direct correlation has not
been established. Generally the lower sandstone, 3—7.6
m (10—25 ft) thick, is fine grained and tightly
cemented. Commonly, however, it is so interbedded
with shale that it is logged as sandy shale, and in con-
sequence, only one or two massive sandstones are rec-
ognized. On the north flank of the dome, the shale con-
tent decreases and the grain size and porosity increase.
There, the uppermost sandstone is commonly 1.5—9 m

 

 

FIGURE 3.—Very large sandstone concretion in upper part of the
upper unit of Flood Member in the N1/2 sec. 36, T. 21 N., R. 2 E.,
Cascade County, Mont.

(5—30 ft) thick, fine to slightly coarse grained, and
slightly to moderately porous. Water has been found in
it at several localities, as in the Border—Red Coulee oil
field, where the “1900-foot water sand” (Erdmann and
Schwabrow, 1941, p. 318) appers to be a homologous
equivalent of the upper unit of the Flood.

In the Disturbed belt west of the South arch, the
basal sandstone of the Flood Member is thin and is
partially replaced by shale. Farther northwest from
Badger Creek, at least as far as the St. Mary River, a
unit of freshwater shale and limestone lies between the
massive varicolored mud rocks typical of the Kootenai
Formation and the black fissile shale typical of the
Flood Member (fig. 4). These freshwater beds are well
exposed along the Burlington Northern Railway
tracks, 6.4 km (4 mi) southwest of East Glacier in the
west center of SE14 sec. 35, T. 31 N., R. 13 W. (Cobban,
1956, p. 1001, 1002). Here the beds consist of the fol-
lowing sequence, numbered from oldest to youngest:

Disconformity. M Ft
4. Shale, olive-gray; some hard layers of siltstone at top 3.6 12.0
3. Limestone, sandy, fossiliferous; weathers brown 1. .8 2.7
USGS Mesozoic 10c. D950:
Protelliptio douglassi (Stanton)
Unio reesideanus Yen
Unio farri Stanton
Stantonogyra silberlingi (Stanton)
2. Shale, olive-gray ________________________________ 4.4 14.5
1. Limestone, gray, massive; weathers brown; crowded
with small poorly preserved gastropods (Reesidella
montanaensis Stanton?). See fig. 4 ______________ 1.2 4.0

These olive-gray freshwater shales disappear eastward
in the subsurface somewhere between the Disturbed
belt and the Cut Bank oil and gas field on the west
flank of the Kevin-Sunburst dome. Wells drilled

10

 

FIGURE 4.—Limestone bed largely formed of freshwater gastropods
in upper part of Kootenai Formation in the SE% sec. 35, T. 31 N.,
R. 13 W., Glacier County, Mont. Hammerhead rests on top of green
mudstone unit that underlies the gastropod limestone bed. Olive—
gray shale containing hard layers of siltstone overlies the gas-
tropod bed.

southwest of the Cut Bank field in the area between
Birch Creek and the Pondera oil field generally show
3—6 m (10—20 ft) of black-gray slightly sandy shale that
forms the base of the Flood Member and rests on mas-
sive varicolored mudstone of the Kootenai Formation.

The question arises whether the olive-gray shales
should be assigned to the Kootenai Formation or to the
Blackleaf Formation. The dark color and fissility of the
shales favor a Blackleaf assignment, whereas the
greenish cast of the shale and the typical Kootenai
fauna suggest a Kootenai assignment. Perhaps the ul-
timate assignment will depend upon which is more
useful to the fieldman, but in this paper they are as-
signed to the Kootenai Formation.

In the subsurface on the Sweetgrass arch, the lower
contact of the Flood Member can be easily determined
in well cuttings by the abrupt change downward from
black-gray shale and light-gray flaggy quartzose
sandstone to massive varicolored mudstone and len-
ticular fluviatile sandstone beds of the Kootenai For-
mation. The sandstones in the upper part of the
Kootenai are generally some shade of greenish gray
and consist of a great variety of colored grains in con-
trast to the predominance of colorless quartz grains in
the sandstones of the Flood Member. The sharpness of
the Kootenai-Blackleaf boundary is considered to indi-
cate a disconformity although all exposed beds noted
appear conformable. Erdmann and Schwabrow (1941,
p. 284) also have described a conspicuous disconformity
between the Kootenai and Blackleaf Formations in the

 

BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

Border—Red Coulee oil field on the north flank of the
Kevin-Sunburst dome.

The upper boundary of the Flood Member cannot be
determined in well cuttings as readily as that of the
lower. It is marked by the change downward from gray
soft bentonitic shale and greenish-gray glauconitic
sandstone of the Taft Hill Member to the light-gray
quartzose sandstone and black-gray shale of the Flood
Member. The contact usually can be determined
within a stratigraphic range of 3—4.5 m (10—15 ft).

AGE ASSIGNMENT AND (I()RR1{1.A'I‘I()N

The upper part of the Flood Member is assigned a
late Early Cretaceous age (late Albian). The lower part
is undated.

On the east flank of the South arch, 9.6 km (6 mi)
south of Floweree in the SE%SW% sec. 19, T. 22 N., R.
6 E. (USGS Mesozoic locality D755), Inoceramus co-
mancheanus Cragin and what may be an undescribed
species of Anomia were found in the sandstone at the
top of the Flood Member. Inoceramus comancheanus, a
marine species of late Albian age, is characteristic of
the Skull Creek Shale of the Black Hills, the Kiowa
Shale of Kansas, and the South Platte Formation of the
Front Range of Colorado.

The dark shale forming the greater part of the mid-
dle unit of the Flood Member in the type section may
have formed in a marine environment, or it may have
been deposited in a brackish-water lagoonal environ-
ment. Only trace fossils have been found in these shale
beds. Some of these forms occur as casts of smooth
sinuous comparatively elongate trail grooves(?) 3 mm
wide and as much as 18 cm long on the underside of
thin beds of sandstone parted by shale or siltstone. No
evidence of hard parts or segmentation have been
noted, and the forms are believed to have been made by
Some species of nematode worm moving over the sur-
face of the mud. Burrows are present but very uncom-
mon. The thin irregular sandstones in the upper part of
the lower unit of the reference section are charac-
terized by two or three other kinds of trace fossils,
noticeably on top of the beds. A very abundant form
consists of short unstriated sinuous trains of very fine
sand 1—2 mm in diameter and as much as 3 cm long,
which may have been left as alimentary waste by
worms. Other trains, less common in occurrence, are
6—15 mm wide, as much as 4.5 cm long, and commonly
are overlain by the smaller form. Nearly all of both
types seem to have been broken. Even more rare is the
form resembling Ophiomorpha, but which is fairly
common in the outcrop just south of the Great Falls
municipal airport. Insofar as known, no other member
of the Blackleaf Formation contains such an abun-
dance of trace fossils. The fragile nature of the re-

FLOOD MEMBER

mains, particularly in their original condition, obvi-
ously precluded much water movement or reworking
and suggests that they originated at or just below
wavebase in an infralittoral or upper neritic environ-
ment and that their parent organisms probably fol-
lowed that environment regardless of how ephemeral
it may have been. Thus, although of little worth for age
determination by paleontologic methods, they are val-
uable intrinsic objects for local recognition of the Flood
Member.

The brown-weathering ripple-marked quartzose
sandstone forming the basal part of the Flood Member
resembles the sandstone (First Cat Creek sand, an
economic term) found at the base of the Colorado Shale
in central Montana as well as some of the sandstone
beds of the Fall River Formation of the Black Hills.
The characteristic black-gray shale middle unit of the
Flood Member resembles closely the 76 m (250 ft) of
black-gray shale that immediately overlies the basal
quartzose sandstone of the Colorado Shale of central
Montana. It is also the type of shale that is charac-
teristic of the very dark Skull Creek Shale of the Black
Hills. The presence of late Albian fossils in the Skull
Creek Shale is further evidence for correlating the
basal part of the Flood Member with the Fall River
Formation and with at least part of the Skull Creek
Shale.

DESCRIP'I‘IVE SECTIONS OF 'I‘HE H.001) MEMBER

The type section and the reference section for the
Flood Member of the Blackleaf Formation described
below are based primarily upon field descriptions. Only
a few representative specimens have been examined
under a binocular microscope, tested for solubility, or
analytically screened for grain size or sorting; none
has been analyzed petrographically or mineralogically.
Further study along these lines, however, should prove
very interesting and worthwhile.

In order to make the two described sections strictly
comparable and fully complementary, the same sub—
divisions have been made for each section. Color de-
scriptions follow the Rock-Color Chart of the National
Research Council (Goddard and others, 1948). Cross-
references within the bed descriptions and to the text
also have been used where identification of individual
beds seems important.

Type section of Flood Member

[Measured thicknesses by R. W. Lemke and C. E. Erdmann, May 15, 16, 1963, on the bluffs
along the south side of Sun River valley, 7.2 km 14.5 mil west of Great Falls. in the
SW‘QNW‘ANE‘Q sec. 7. T. 20 N., R. 3 E., Cascade County (Great Falls quadrangle] Ifig. 5!}

M Ft
Pleistocene glacial lakebed silt.
Blackleaf Formation:
Taft Hill Member, basal part:
33. Bentonite ________________________________ 0.2 0.5
32. Shale, medium-gray, soft, slumped ________ .6 2.1

 

11

Type section of Flood Member—Continued

Blackleaf Formation—Continued

 

 

 

Disconformity.
Flood Member:
Upper unit: M Ft
31. Shale, gray; interbedded with 2—4-cm layers
of cherty ripple—marked medium-light-
gray sandstone that weathers to olive gray .9 2.9
30. Sandstone, light-yellowish-gray, silty, fine-
grained, thinly and irregularly bedded;
weathers to light brownish orange; slight
carbonaceous wisps along parting planes
(current bedding). This is the horizon con-
taining concretions which are not present
on northwest side of draw but are present
on southeast side of draw and abundant
on north side of Sun River valley in
NWWNE‘ANE‘A; sec. 5, T. 20 N., R. 3 E. __ 3.2 10.4
LITHOLOGIC
SYMBOLS
Sandstone
E Siltstone
:1
E
D.
S
Shale
METHES FEET
. —~ . [H1111]
E
—E Bentonite
—— 20
— 40
SEC. 7
.. T. 20 N.,
E R. 3 E.
:2 s s
I) _ T W a
‘E 60.18
E 20 — T
E
o 1M|LE
o 1 KILOMETRE
E
3
a
i
o
.1

 

 

 

FIGURE 5.—-Type section of the Flood Member of the Black-
leaf Formation and map showing line of measured section,
sec. 7, T. 20 N., R. 3 E. Numbers on the left side of the
column are key beds in the measured section. On the map,
the arrow points upward stratigraphically; B, base, and T,
top of member.

12

Type section of Flood Member—Continued
Blackleaf Formation—Continued
Flood Member—Continued

Upper unit—Continued M

29. Sandstone, medium-light-gray salt—and-
pepper appearing, generally massive;
weathers yellow gray stained with limo—
nite; consists mostly of well-rounded to
subrounded quartz and slightly less (3:2)
chert and a few brown grains in a matrix of
secondary calcite

28. Sandstone, concretionary, calcareous,
medium-light-gray (N 6); weathers dark
yellowish brown (10YR 4/3) to moderate
brown. Probably nearly equal parts of sec—
ondary calcite cementing fine channel sand
containing a small amount of ferruginous
material. Concretion about 12 m (40 ft)
long with maximum thickness at southeast
end. Top flat, thinly bedded, flush with sur-
face of underlying bed; lower part massive,
definitely truncating bedding of underly-

ing sandstone. Unit thins to featheredge 1.4

27. Sandstone, grayish-yellow, fine-grained,
very friable; bedding indistinct; thickness

varies 3.0

26. Sandstone, grayish—yellow, medium—grained,
well-sorted; some chert; crossbedded, with
dip of foreset beds to the southwest. Gener-
ally massive except for about five distinct
parting planes. Looks like a near-beach

deposit ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 1.6

25. Sandstone, grayish—yellow, fine-grained, in-
distinctly bedded, friable, slightly calcare—

ous ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 1.9

24. Sandstone, grayish-yellow, ‘fine— to me-
dium-grained, massive; weathers to gray-
ish orange yellow; mostly quartz. Top sur—
face has a thin film of medium-gray clay.
Forms a prominent ledge overhanging

beds below

23. Sandstone, light-yellowish-gray, indistinct-
ly bedded, fairly friable and erodible. Up-
per 36 cm weathers yellowish orange
(10YR 6/6) and is thinner bedded than
part below ____________________________

22. Sandstone, light-olive-gray; fine-grained,
hard to soft; weathers pale yellowish
brown to yellowish gray. Some flute casts
and abundant casts of trace fossils ...... .7

3.8

1.4

21. Sandstone, light-gray, fine—grained, silty,
poorly sorted; some finely macerated car-
bonaceous debris; nodular or chunky ap-
pearance. Trace fossils on some bedding
surfaces. Basal part shaly siltstone 111111 .9

20. Sandstone, light-gray, silty, poorly sorted; a
few rounded granules of dark chert; nodu-
lar or chunky. Contains occasional discrete
masses of concretionary marcasite as large
as 6 by 10 cm. Supports a low rounded
bench ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, _&

Thickness of upper unit .............. 20.1

Disconformity.

Ft

1.1

4.5

10.0

5.1

6.2

12.6

4.7

2.3

3.2

m
55‘!“
00:

 

BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

Type section of Flood Member—Continued
Blackleaf Formation—Continued
Flood Member—Continued
Middle unit:

19. Limestone, medium-dark-gray, silty; weath-
ers light gray to pale yellowish gray; con-
cretionary, with cone-in-cone structure __

18. Siltstone, medium-gray; highly calcareous,
grading upward into sandy calcareous
siltstone containing a few granules of
polished dark chert ,,,,,,,,,,,,,,,,,,,,

17. Shale, dark-gray (N 3), very fissile ........

16. Sandstone, medium—gray, medium- to
coarse-grained; thin nodular layers sepa-
rated by laminae of dark-gray shale.
Poorly exposed ________________________

15. Slope concealed by colluvium and talus.
Probably soft dark-gray fissile shale

14. Shale, grayish-black, carbonaceous, soft, fis-
sile, papery ____________________________

13. Shale, medium-dark-gray, poorly exposed -1

12. Sandstone, yellowish-gray, medium-grained;
upper surface ripple marked, ferruginous,
weathers medium brown. Lower 2 cm silty,
containing small fragments of mineral
charcoal (fusain) and trace fossils. A local
asymmetric channel sand trending approx—
imately east; maximum width about 12 m
(40 ft) with thickest section on north side

11. Shale, dark-gray, silty, fissile ............

Thickness middle unit ________________

Lower unit:

10. Sandstone, light-gray, fine— to medium—
grained, slightly ferruginous; in wavy
layers 12—23 cm thick, alternating with
somewhat thinner beds of siltstone. More
indurated and better sorted than lower
part of unit. Crossbedding, dipping south—
west. Uppermost layer, 15 cm thick, of
hard medium-gray sandstone conspicu-
ously overhangs beds below. Forms a rag—
ged cliffy slope ,,,,,,,,,,,,,,,,,,,,,,,,

9. Siltstone, shaly, yellowish-gray, moderately
friable; weathers grayish orange; contains
three or four thin more resistant beds of
fine—grained quartz sandstone with a little
clastic mica. Trace fossils. Forms a ragged
cliffy slope ____________________________

8. Sandstone, light—olive-gray, quartzose; in-
terbedded with about equal amounts of
shaly siltstone with laminae marked by
films of carbonaceous matter; trace fossils
sparsely present, poorly preserved. Beds
parted by short 1-cm-thick lentils of
medium-dark-gray shaly siltstone which
appear to represent mud-filled troughs of
ripple marks. Depositional environment
probably marine tidal fiat ,,,,,,,,,,,,,,

7. Slope, concealed by colluvium ,,,,,,,,,,,,

6. Siltstone, yellowish-gray (5Y 7/2), poorly fis-
sile; rests on light-olive-gray silty shale
(5Y 6/1) ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Thickness of lower unit ..............

Total measured thickness of Flood
Member

M Ft
.1 .4
.5 1.6
.5 1.5
1.3 6.0
6.3 20.7
.6 2.0
4.6 15.0
.6 2.0
.6 2.0
15.3 50.2
1.0 3.7
3.1 10.0
1.0 3.2
1.0 3.2
i 2.0
E 2.1

,,,,,,,,,,,,,,,,,,,,,,,,,,, 42.1 138.3

Type section of Flood Member—Continued
Disconformity.
Kootenai Formation, upper part:
5. Sandstone, arkosic, light-gray; fine- to
medium-grained, friable, slightly to mod-
erately calcerous; weathers light tan 11--
4. Shale, sandy, light-olive-green, only slightly
fissile __________________________________
3. Sandstone, grayish-brown, very fine grained,
vertically jointed, calcareous, well-
indurated ______________________________
2. Shale, sandy, maroon, only slightly fissiled
1. Shale, sandy, light-olive-green, slightly fis-
sile _____________________________________

Total measured thickness of part of
Kootenai Formation ,,,,,,,,,,,,,,,,

Reference section of Flood Member

FLOOD MEMBER

M Ft
.5 1.6
.2 .7
.2 .8
2 .7

_-.5_ u

1.7 5.5

[Measured by C. E. Erdmann, Oct. 4—10, 1965, on south-pointing spur on north valley wall
of Sun River, about 5.6 km (3.5 mi: northwest of the city of Great Falls, 0.5 km (0.3 mi)
northeast of Emerson Junction of Burlington Northern Railroad spur track of Chicago,
Milwaukee, and St. Paul Railway. Base of section is in the NW‘ANE‘ANE‘A sec. 5. T. 20
N., R. 3 13.; top of section is in the SW‘ASW‘ASE‘A sec. 32, T. 21 N., R. 3 E]

Pleistocene deposits (very thin).
Blackleaf Formation:
Taft Hill Member, basal part:
64. Shale, dark-gray, fissile, poorly exposed__-,
63. Sandstone, medium-coarse, cherty, calcare-
ous. Surface weathers dark brown ,,,,,,
62. Shale, very dark gray, very fissile ________
Flood Member:
Upper unit:
61. Sandstone, concretionary, fine-grained, cal-
careous, moderately gray. Concretions
(large) are epigenetic and occupy scour
channels in underlying sandstone ,,,,,,
60. Sandstone, light-yellowish-gray, fine-
grained, calcareous. Irregular wavy bed—
ding 3—6 cm thick, parted by thin 6-mm
laminae of medium-gray shale ,,,,,,,,,,
59. Sandstone; similar to bed 56 below. Poorly
sorted. Fine horizontal laminae. No cross—
lamination ____________________________
58. Sandstone, grayish-orange, fine—grained,
calcareous. Similar to upper part of bed
53 ____________________________________
57. Sandstone, light-yellowish-gray, fine- to
coarse-grained, poorly sorted, cherty, tuf-
faceous, cross-laminated; thin planar
layers dip 20° S.—20° W. Makes ledge 1-1,
56. Sandstone, grayish-orange, fine-grained.
Similar to upper part of bed 53 below ___,
55. Sandstone, light-yellowish-gray, medium-
grained, massive, hard. Makes ledge with
small overhang ________________________
54. Sandstone, light-yellowish-gray, fine-
grained, calcareous; weathers grayish
orange. Irregular wavy layers 3-6 cm thick
parted by thin (0.5 cm) laminae of me-
dium-gray shale ________________________
53. Sandstone, as immediately above, but fresh,
light-yellowish-gray, unweathered. Makes
top of excavated slope __________________
52. Sandstone, olive-gray, medium-grained,
poorly sorted, soft; contains irregular

M Ft
0.6+ 2.0+
.3 1.0
1.7 5.5
1.7 5.6
3.3 10.7
.2 .5
1.3 4.3
.4 1.4
.6 2.0
.4 1.2
2.0 6.7
2.6 8.5

 

52.

51.

50.

49.
48.

47.
46.

45.

13

Reference section of Flood Member—Continued
Blackleaf Formation—Continued
Flood Member—Continued
Upper unit—Continued

Sandstone, etc.—Continued
masses and partings of soft medium-gray
shale ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Sandstone, light-gray, fine-grained, hard,
massive. Trace fossils on both base and
top ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Sandstone, light-gray, fine-grained; thin
(3-cm) partings of medium-gray fissile
shale at 15-cm intervals ________________
Siltstone, olive, soft, clayey ______________
Sandstone, light-gray, fine-grained, faintly
calcareous; traces of carbonaceous debris;
in small lenticular to nodular masses 3—7
cm long, commonly enclosed by thin (1 cm)
rinds of sandy gray clay. Bedding indis-
tinct; resistant, ledge making. Upper 0.5 m
weathers grayish orange ,,,,,,,,,,,,,,,,
Shale, medium—gray (east side of spur) -11,
Sandstone, olive, soft, massive; irregular in-
clusions of shale ________________________
Sandstone, light-yellowish-gray, poorly
sorted, fine- to medium-grained, hard,
faintly calcareous; a sprinkle of fine to
coarse grains of rounded polished black
chert, flakes of carbonaceous material, and
clay galls; in small lenticular and nodular
masses 2—8 cm long and 2—10 cm thick,
some of which are encased or wrapped by
rinds of light-medium-gray clay. Bedding
very indistinct. Makes broken rubbly
ledge. Lower 3—6 cm weathered dark yel-
lowish orange (possible diastem) ________

Total thickness of upper unit ________

Middle unit:
44. Siltstone, olive-gray, sandy; in layers about

43.

42. Shale, olive, fissile

15 cm thick interbedded with medium-
dark-gray shale and olive shale. Surface
weathers into tough structureless mud—
stone __________________________________
Shale, medium-dark-gray; thin lentils of
olive sandstone ________________________

41. Sandstone, light-olive-gray, poorly sorted,

fine- to coarse-grained, subangular, non-
calcareous, soft, friable; surface weathers
dark yellowish orange with small internal
splotches of dusky yellow and light olive
brown, phasing into the external color;
some rounded granules of gray chert; all in
a matrix of light-gray clay which also
marks indistinct laminae ______________

40. Shale, dark-gray, fissile (as below) ________

39.

Sandstone, olive-gray, fine-grained; thin
slabby layers. Base slightly wavy (un-
dulating), marked by 1 cm of dark-yellow
ochre __________________________________

38. Shale, black, very fissile (papery). Very thin

layer of light-gray fine-grained finely
laminated sandstone 0.8 m above base of
bed ____________________________________

M Ft
5 1.5

1 .3
1.0 3.3
1 .4

1 7 5.5
8 2.5

.6 2.0
_6 1.9
17.9 58 3
2 4 8.0

1 2 4.0
3 1.0

1 .4

1.7

.3 .9
1.4 4.5

14 BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

Reference section of Flood Member—Continued
Blackleaf Formation—Continued
Flood Member—Continued

Middle unit—Continued M

37. Sandstone, olive-gray, fine-grained, finely
laminated; weathers brown. Base exhibits
casts of worm trails and a burrow. Top
marked by 1 cm of dark-yellowish-orange
siltstone whose surface shows trace fos-
sils ____________________________________ .1

36. Shale, dark—gray, fissile; laminae very thin,
almost papery, soft

35. Siltstone, light-olive-gray ________________ .1

34. Sandstone, light-olive-gray to medium—
light—gray, fine-grained, poorly sorted,
massive, poorly stratified; weathers light
yellowish brown to dark yellowish orange.
Organically reworked; numerous galls and
small irregular masses of dark-gray clay
shale may represent burrow fillings from
overlying bed. Oval siltstone casts of flat-

tened tubes (worm burrows?) ____________ .7
33. Shale, dark—gray, soft, fissile. Thickens to
1.7 m on west side of spur ______________ .8

32. Siltstone, light-olive-gray; encloses a 12-cm
pale—yellowish-brown bed in middle. Thin
layers of shaly sandstone at base and top.
Unit thickens to 0.9 m on west side of

spur __________________________________ .5
31. Shale, light-olive-gray. Similar to bed 29,
below __________________________________ 1.8

30. Siltstone, pale-yellowish-brown (10YR 6/2) .1
29. Shale, light-olive—gray (5Y 6/1), poorly fis-
sile, soft
28. Siltstone, light-olive—gray; in beds 12—15 cm
thick parted by 1-cm laminae of fine-
grained olive sandstone. Numerous trace
fossils (worm castings or trails?) on each
upper surface. Thin layer of siltstone in
middle weathers reddish brown. Layer of
reddish—weathering marcasite(?) nodules
at top, 3—6 cm thick ____________________ .5
27. Siltstone, light-olive—gray. Contains thin
3—6-cm-thick sandstone layers; those in
middle show ripple-marked upper surfaces
with relief of 2 cm. Numerous trace fos-
sils ____________________________________

is

26. Dolostone. Hard compact masses about 60
cm in diameter. Usually considerably shat—
tered. Fresh surfaces medium gray, but
weather to moderate brown (5YR 4/4) in
rinds as much as 2 cm thick. Some frac-
tures are dusted with small calcite crys-
tals ___________________________________

25. Siltstone, light-medium-gray, soft, clayey W

Total thickness of middle unit ,,,,,,,,,,

._i
w . .
N) N) H

II-

Diastem(?)
Lower unit:

24. Sandstone, light-yellowish-brown, fine-
grained; in layers 9—15 cm thick parted by
laminae of medium-gray siltstone. Trace
fossils (casts of worm trails?) on upper sur-
faces. Rock breaks into flat slabby hand-
sized pieces 1—2 cm thick ________________ 1.2

Ft

2.4

2.8

1.6

1.0

1.6

1.3

4;
Ham.»

3.8

 

Reference section of Flood Member—Continued
Blackleaf Formation—Continued
Flood Member—Continued
Lower unit—Continued M
23. Siltstone, light—olive-gray, sandy, soft ,,,,,, .2
22. Sandstone, light-yellowish-gray, fine—
grained; in layers 9-15 cm thick, interbed-
ded with light-olive sandy siltstone. Upper
surfaces show trace fossils ,,,,,,,,,,,,,, .4
21. Siltstone, light-olive—gray; 15-cm layer of
light-olive-gray fine-grained massive
sandstone in middle which is overlain by a
6-cm layer of medium-dark-gray siltstone.
Trace fossils on upper surface of the
sandstone ______________________________ .5
20. Sandstone, light-yellowish-gray, fine—
grained; small flakes of carbonaceous de-
bris, faintly calcareous; in even ELI2—cm
finely laminated layers separated by thin
(6 mm) laminae oflight-gray siltstone with
worm castings. Hard, resistant. Makes
subdued ledge with slightly undulating
top 1 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, .7
19. Sandstone, light—yellowish-gray, very fine
grained; in 6—12-cm layers interbedded
with layers of light-olive-gray siltstone of
about same thickness. Bedding marked by
very thin laminae (films) of gray clay.
Trace fossils (casts of worm trails?) present
but fragmentary ________________________ .4
18. Sandstone, light-olive, very fine grained,
silty __________________________________ .3
17. Siltstone (or very fine grained sandstone),
light-olive-gray, massive, nonfissile,
tough __________________________________ .3
16. Sandstone (or siltstone), light—yellowish—
brown to moderate—yellowish-brown (10YR
5/4), fine-grained. Makes weak massive
ledge. Contact with underlying bed grada-
tional __________________________________ .6
15. Claystone, bentonitic, silty; predominantly
medium dark gray but olive at base and
top. Breaks with subconchoidal fracture;
becomes flaky upon weathering ,,,,,,,,,, A
Thickness of lower unit ,,,,,,,,,,,,,,,,
Total thickness of Flood Member
Erosional disconformity.
Kootenai Formation, upper part:
14. Siltstone, light-olive—gray (5Y 6/1), thinly lami«
nated; Chippy where sandy __________________ 0.4
13. Mudstone, medium-dark-gray, sandy, poorly fis-
sile, hard, tough; some slight mottling by light
olive green ________________________________ .2
12. Siltstone, light-yellowish-gray, soft, clayey ___, .1

11. Sandstone, light-yellowish-gray, medium-
grained, noncalcareous, firm, massive; makes
subdued ledge ______________________________ .5

10. Claystone; light-greenish-gray when damp;
weathers light yellowish gray ,,,,,,,,,,,,,, ,1

9. Claystone, soft; predominantly dusky red with
some mottling (blebs) of dusky yellow green
(5GY 5/2) __________________________________ 1.9

8. Siltstone; dull medium olive gray mottled pale

Ft
.6

1.2

1.7

2.2

1.4

1.0

1.8

1.3

1.6

6.2

TAFT HILL MEMBER

Reference section of the Flood Member—Continued
Kootenai Formation, upper part—Continued

8. Siltstone, etc—Continued M Ft

olive gray by small rounded masses of fine

sandstone. In flat layers 9—15 cm thick contain-

ing fine carbonaceous debris. Slakes down into

thin flakes. Some manganese stain with a

dull-purplish cast __________________________ .8
7. Sandstone, fine- to medium-grained; cemented by

calcareous clay; medium gray with greenish

cast; some joint faces weather moderate brown.

Unit is a lenticular body about 12 m wide. Bed-

ding in lower 30 cm is thin and indistinct;

upper part more resistant, with hard 6—

9-cm-thick massive layers that weather into

large rounded blocks. Upper surface cut by

sand-filledjoint cracks 5 cm wide that strike N.

60° E. Occurrence suggests a lenticular depres-

sion fill trending N. 40° W. but not a running-

water or channel sand because of the absence of

planar cross-lamination. Other sand bodies

occur nearby at same horizon
6. Mudstone, brownish—red. A wedge thinning

rapidly to the northeast into a basin of overly-

ing sand mass and seems to come up on other

side. Local absence may result from scour in

channel or it may have been squeezed out by

load effect. Top gradational upward __________ .2 .8
5. Siltstone, sandy, light-olive-gray. Lower part

clayey with nodular weathering. Upper 2.5 cm

thinly laminated. Base cut into underlying

bed ________________________________________ .5
4. Mudstone, clayey; alternate layers of brownish

red and light olive gray but locally is all brown-

ish red; crossbedded ________________________ .8
3. Mudstone, grayish-red (10R 4/2); similar to bed

1. Thin (6 cm) layer of greenish-gray siltstone

21 cm above base. Nodular weathering very

well developed above green layer and indicates

stratification. Nodules are oval in cross section

and may be 3.6 cm long and 1.5 cm thick ”-1 .7
2. Siltstone, light-olive-gray, clayey, firm, compact,

massive; joint faces smooth, but interior of bed

has nodular structure. Thickness fairly uni-

form ______________________________________ .4 .14
1. Mudstone, grayish-red (10R 4/2), silty, finely

micaceous, firm, massive, compact. Base con-

cealed

2.6

1.5 5.0

1.5

2.5

2.3

1.2+ 4.0+

Total measured thickness of part of Kootenai

Formation 9.3+ 27.4+

TAFT HILL MEMBER

NAME AND DEFINITION

The Taft Hill Member overlies the Flood Member
and underlies the Vaughn Member. The Taft Hill
Member consists chiefly of medium-gray soft bentonit-
ic clayey to silty shale and fine-grained greenish-gray
glauconitic sandstone; the unit is the glauconitic
sandstone member of Cobban (1951a, p. 2177—2179).
The member represents shelf deposits of the neritic
zone of the first major transgression of the Lower Cre-

 

15

taceous sea. Cobban, Erdmann, Lemke, and Maughan
(1959, p. 2790) named the member for exposures along
the east and north slopes of Taft Hill, a prominent
dissected bench extending from 2.4 to 9.6 km (1.5—6 mi)
south of the Village of Vaughn (Vaughn and Cascade
quadrangles). The type section is a composite of meas-
urements from four localities south of the Sun River
between the east face of Taft Hill and a point 8 km
(5 mi) farther east, the top being near the NM; cor. sec.
12, T. 20 N., R. 1 E. (Vaughn quadrangle), and the base
at Newman Spring, in the center ofsec. 9, T. 20 N., R. 2
E. (Great Falls quadrangle). In general the beds in the
lower half are so soft and poorly indurated that 10—20
percent of the total thickness of the type section is con-
cealed. However, exposures made in 1960 and 1961
north of the Sun River during construction and rerout—
ing of U.S. Interstate Highway 15 between Great Falls
and Vaughn junction permitted study of excellent sec-
tions of the lower part of the member and of the under—
lying Flood Member. Descriptions and measurements
from these localities, which are 5.6—8 km (3.5—5 mi)
north and northeast of the type section of the Taft Hill
Member, are described in this report as a composite
reference section. Thus only about 1 In of the lower
40 m (132 ft) of the member in the Great Falls area has
not been described from surface exposures and this
interval was penetrated during 1960 by the U.S. Corps
of Engineers in core hole I—10 (310x), NWMiNWI/i sec.
19, T. 21 N., R. 2 E., near Vaughn junction.

’I‘HICKNESS

The Taft Hill Member is 74 m (242 ft) thick in its
type section south of the Sun River and is 76 In (249 ft)
thick north of the Sun River in the area of the refer-
ence section. It has a comparatively uniform thickness
over the central and eastern part of the Sweetgrass
arch, with the thickness in the Great Falls area being
about average. On the east flank of the South arch,
Cobban measured 81 m (266 ft) in outcrop in sec. 17, T.
22 N., R. 6 E. (Lander Crossing quadrangle), and 74 m
(242 ft) between the depths of 718.7 and 792.5 m (2,358
and 2,600 ft) in the Texas Company—Kiemele well 1 in
the SE%NW%NE% sec. 26, T. 31 N., R. 13 E., Hill
County. This line represents the east limit of the area
in which the name may properly be applied. Farther
east in the Bearpaw Mountains, Kerr and others
(1957) reported 30—46 m (100—150 ft) of glauconitic
beds in the Newcastle Sandstone equivalent in the
Colorado Shale. Cuttings from a few tests for oil and
gas along the crest of the South arch and high up on its
west flank reveal thicknesses of 61—82 m (200—270 ft)
for the Taft Hill. In the Pondera oil field (T. 27 N., R. 4
W.), there is a good sample thickness of 73 m (240 ft).
In several old wells in the central and eastern part of

16

Kevin-Sunburst dome (Tps. 32—34 N., Rs. 1 E.—1 W.),
where in one well the member was cored, thicknesses
range from 70 to 72 m (230 to 235 ft). In the West
Kevin district (T. 35 N., R. 3 W.), however, the member
has thinned to 68.6 m (225 ft), and in one well in the
Border—Red Coulee field (T. 37 N., R. 4 W.) to 61 m (200
ft). Apparently the thinning to the west and north re—
sults from replacement by nonmarine sediments (dis-
cussed in description of the Vaughn Member). In tests
drilled along the southwest margin of the Sweetgrass
arch, the Taft Hill Member thins to 55 m (180 ft) or
slightly less. Farther west, in the. Sun River Canyon
area, Mudge (1972, p.A58—A60) noted that the Taft
Hill Member thickened westwardly from 68 to 183 m
(225—600 ft). In more recent investigations, Gwinn
(1961) applied the name Taft Hill Member of the
Blackleaf Formation to 273—305 m (900—1,000 ft) of
strata in the noncontiguous Drummond area (T. 11 N.,
R. 12 W., Granite County), about 80 km (50 mi) south-
west of Great Falls, where he described the lower 91 m
(300 ft) as “crossbedded marine sandstones.” However,
Gwinn did not mention the presence of glauconite (the
definitive mineral at the type section), and although
his basal unit well may be the time equivalent of some
part of the type Taft Hill Member, further study is
required before the name can be definitely applied in
the Drummond area.

Old—CROP INSTRIBLJ'I‘ION

Outcrops of the Taft Hill Member on the Sweetgrass
arch are most extensive on the southern part of the
South arch. Some of the best exposures, including parts
of the type and reference sections, are near Vaughn,
where they have been mapped by Maughan (1961).
West from Vaughn the member crops out upstream
along the south bank of the Sun River for 8 km (5 mi)
before the regional west dip of the South arch carries it
below the valley floor. South of Vaughn the upper part
of the member is exposed extensively along the east
side of Taft Hill from the north edge of sec. 35, T. 21 N.,
R. 1 E., in the Vaughn quadrangle, south at least to a
point 6.4 km (4 mi) west of Ulm in sec. 3, T. 19 N., R. 1
E., in the Cascade quadrangle. Locally, the lower part
is exposed in ravines or along roadcuts for 3.2—4.8 km
(2—3 mi) east of Taft Hill. Northwest from Vaughn the
member crops out fairly continuously up Muddy Creek
for about 6.4 km (4 mi). Eastward it is exposed across
the southern part of the Great Falls quadrangle, and
northeastward through the Portage quadrangle to the
Missouri River where outcrops extend into the Lander
Crossing quadrangle and swing south along the west
flank of the Highwood Mountains. Exposures also have
been observed in the Sweetgrass Hills Where the
member is distinguished by a 6—15-m (20—50-ft) glau—

 

BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

conite-bearing sandstone that probably is equivalent
to the Second Whitlash sand of economic usage at
Whitlash dome (Bartram and Erdmann, 1935, p. 274).

Along the Rocky Mountains front west of the South
arch, a nonglauconitic marine time-equivalent of the
Taft Hill Member crops out in the Disturbed belt. It is
well exposed along the western edge of the tier of town-
ships from T. 20 N., R. 8 W., north through T. 25 N., R.
8 W., and, thence, northwest to Birch Creek in T. 28 N.,
R. 10 W. Farther to the northwest, along the southeast
boundary of Glacier National Park, those strata
undergo a facies change by interfingering with and
finally complete replacement by the nonmarine bento-
nitic Vaughn Member.

Glauconitic sedimentation, probably in an environ-
ment paralleling its occurrence in the Taft Hill
Member, also may have operated more or less contem-
poraneously with the deposition of the Spinney Hill
Member of the Joli Fou Formation in west-central
Saskatchewan (Edwards, 1960), and the Bluesky For-
mation at the base of the Fort St. John Group in the
Peace River country of northern Alberta. Equivalents
of both the Joli Fou and the Bluesky Formations occur
at the base of the Colorado Group as that group is used
in that report area. Indirect correlation with the Taft
Hill is suggested by the relationship of the Joli Fou
Formation to the Skull Creek Shale in the southern
part of the Williston basin (Edwards, 1960, p. 150). A
much more direct correlation may be the development
of glauconite in sandstone that rests directly on the
Kootenai Formation in the Northern Pump-Emil
Guertzgen well 1, SW%NW%NE%. sec. 2, T. 31 N., R.
19 E., Bowes field, Blaine County, north of the Bear-
paw Mountains. In the absence of the Flood Member
which has wedged out farther west, the occurrence of
Taft Hill lithology on Kootenai is directly analogous to
the Spinney Hill sand—Mannville Formation relation-
ship in Saskatchewan.

GENERAL DESCRIl’l'ION

As noted previously, the boundary of the Taft Hill
Member with the underlying Flood Member is essen-
tially transitional and has been placed arbitrarily at
the first appearance of marine rocks following the final
episode of deltaic or barrier-island deposition marking
the close of the Flood Member. The contact with the
overlying Vaughn Member appears to be a disconform-
ity marking a change from a marine to a continental
environment.

Dark-gray soft bentonitic shale and greenish-gray
glauconitic sandstone characterize the Taft Hill
Member. The shale constitutes about 35 percent of the
member in the type section and in the reference sec-
tion, glauconitic sandstone about 25 percent, and

TAFT HILL MEMBER

nonglauconitic sandstone, siltsone, and thin concre—
tionary limestone beds about 40 percent of the
member. The sandstone beds generally crop out as low
rounded ledges, whereas the shale beds form medium-
gray poorly vegetated spongy slopes. Some of the con-
cretionary limestone beds exhibit cone—in-cone struc-
ture and weather brown.

On the basis of lithology, the member can be sub-
divided into three units. The lower unit consists chiefly
of bentonitic shale, the middle unit of glauconitic sand-
stone, and the upper unit of mostly quartzose
sandstone, siltstone, and bentonitic shale. The follow—
ing detailed descriptions of these units are based upon
descriptions of lithologies in the type and reference
sections and in other exposures in the vicinity. (See
descriptions and graphic sections that follow later.)

Lower unit.——The lower unit is approximately 22 m
(72 ft) thick at the type section. Shale, medium-dark-
gray and poorly to moderately fissile, is the predomi-
nant lithology. Siltstone and glauconitic sandstone
constitute most of the remainder. A few thin beds of
bentonite account for the rest. A bentonite bed 0.6 m (2
ft) thick and about 0.3 m above the base of the unit in
the type section makes an easily recognizable marker
for differentiating the Taft Hill Formation from the
underlying Flood Member because of the absence of
bentonite beds in the underlying member. The bento-
nite bed is overlain by approximately 7 m (23 ft) of
dark-gray fissile shale which closely resembles the
shale of the middle unit of the Flood Member. Overly-
ing the shale is a 0.6-m (2-ft)-thick glauconitic
sandstone, which, locally, is the first appearance of
glauconite in the Taft Hill Member. Above the
glauconitic sandstone is about 6 m (20 ft) of soft dark-
gray to medium—light-gray shale and siltstone. The
upper approximate 7.6 m (25 ft) of the unit consists ofa
series of glauconitic sandstones and interbedded thin
bentonites. The glauconitic sandstones are similar to
those of the overlying middle unit, but they are more
poorly indurated and, except for the lowest 1.5-m (5-
ft)-thick sandstone, are rarely exposed. Knowledge of
this part of the unit is obtained from the composite
reference section.

Middle unit—This unit is approximately 9 m (30 ft)
thick at the type and reference sections. Because of the
predominant lithology, it has commonly been referred
to as “the glauconitic sandstone.” Beds immediately
underlying the middle unit are not exposed in the type
section or in other natural outcrops in the area. How-
ever, the basal part of the unit and about a 7.6-m (25-
ft) section of the underlying beds of the middle unit are
exposed in a highway cut about 0.6 km to the east
(NEMISElfli sec. 19, T. 21 N., R. 2 E.), and about 0.3 In of
shale is exposed overlying the unit in a highway cut at

 

17

Vaughn junction (approximate center of sec. 19, T. 21
N., R. 2 W.). In the absence of a more continuous se-
quence of beds, the middle unit in the type section and
in other places has been positioned into the reference
section of the member by aerial projection, taking into
account the local dip of the beds. In the type section,
the middle unit has been described as one bed (bed 14).
In the reference section, this unit has been subdivided
into a number of beds, more or less transitional with
each other. Parts of the unit crop out in a number of
places from Vaughn eastward across the southern
parts of the Vaughn and Great Falls quadrangles.
Farther east the glauconitic sandstone thins or grades
laterally into shale, as indicated by its absence along
the Missouri River in the eastern part of the Portage
quadrangle. Southwest of the type section, the unit ap-
pears to thicken, 15 m (50 ft) of very glauconitic
sandstone being penetrated at depths of 104—119 In
(340—390 ft) in a well 4.8 km (3 mi) to the south in the
NW%SE% sec. 12, T. 20 N., R. 1 E. Also, glauconitic
sandstone as thick as or thicker than in the well crops
out farther south in the SW% sec. 17, T. 17 N., R. 1 E.,
but the strata are much disturbed and an accurate
measurement has not been made.

The glauconitic sandstone is mostly olive green
(10Y 5/2 to 10Y 5/4), fine to medium grained, and in
layers (beds) commonly 15—60 cm (0.5—2 ft) thick. A
few thin clay-ironstone concretionary masses having
cone-in—cone structure constitute about the only varia-
tions in an otherwise essentially homogeneous unit.
The upper part of the sandstone generally is thicker
bedded and coarser grained than the lower part. The
upper part also commonly exhibits a planar (“torren—
tial”) type of cross lamination, which is indicative of a
shallow current entering quiet water of greater depth.
Bedding surfaces in places show worm(?) castings or
borings on ripple marks. Chunks of petrified wood,
8—10 cm long, were found near the top of the sand-
stone unit at one locality (NWIANWMI sec. 26, T. 21 N.,
R. 2 E., just east of Vaughn. The lower part of the
sandstone unit is argillaceous and generally more
friable.

Samples from the middle and upper parts of the
sandstone from the type section 2.4 km (1.5 mi) south
of Vaughn and from an exposure at the junction of US.
Highways 89 and 91 about 0.4 km east of Vaughn were
studied for mineral composition by W. T. Pecora (Cob-
ban, 1951a, p. 2177—2178). He reported that the sam-
ples consisted of approximately 30 percent clear
quartz, 25 percent murky chert, 10 percent glauconite,
5 percent fresh feldspar, and 30 percent coarse calcite
(cementing material). The quartz and chert grains are
well rounded and well sorted. Pecora stated that the
glauconite was an impure type formed “in a marine

18 BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

environment by replacement of material that was orig-
inally ferromagnesian, such as hornblende.”

Upper unit—In the type section the upper unit is
approximately 43 m (140 ft) thick. The entire unit is
exposed at the type section, except approximately the
basal 1.2 m, which probably is bentonitic shale. The
thickness of the covered 1.2 m interval between the
upper unit and the middle unit was estimated by areal
projection between the two localities, taking into ac-
count the local dip.

The upper unit consists predominantly of bentonitic
shale and bentonitic siltstone, which, together with
three beds or bentonite beds, form a generally gray
poorly vegetated spongy slope (fig. 6). A bed of brown-
weathering calcareous concretions, characterized by
cone-in—cone structure, is present 3.7 m (12 ft) above
the base. Beds of sandstone are present here and there
but are thickest and most numerous near the top. They
are chiefly light olive gray, fine grained, and somewhat
glauconitic and bentonitic. About 3 m below the top of
the unit in the type section is a 1.1—m—thick bed of
fine-grained sandstone that persists as a ledge former
across the Vaughn and Great Falls quadrangles and

 

into the Portage quadrangle, where it thickens to 2.4
In. On the east face of Taft Hill, a thin bed of coarse-
grained sandstone lies about 0.9 m below this ledge
maker. Locally, south of the county road near the
center of the north line of sec. 18, T. 20 N., R. 2 E., this
coarse bed is represented by conglomerate that consists
of pebbles as much as 5 cm in diameter of gray, green,
and reddish quartzite and black-coated gray, black,
and brown chert. In the type section, this bed (bed 31)
is fine to coarse grained, thin bedded to massive, and
has undetermined green grains. It contains a few poor-
ly preserved molds of freshwater unios and gastropods
and fragments of large bones, probably dinosaurian.
Possibly the bed represents a littoral deposit into
which the freshwater elements were washed. Deposi-
tion in either shallow marine water or brackish water
is indicated for the 3.1 m (10.2 ft) of sandstone (bed 34)
at the top of the member by the presence of the
brachiopod Lingula subspatulata Hall and Meek.

A015. ASSIGNMENI' AND CORRELATION

Fossils are scarce in the Taft Hill Member in its type
section west of GreatFalls. A small marine fauna with

 

FIGURE 6.—Upper bentonitic part of upper unit Taft Hill Member on the north face of Taft Hill in the SVzSE‘/4 sec. 1, T. 20 N., R. 1 E.,
Cascade County, Mont. Sandstone, forming ledges on upper part of slope on right side of photograph, is basal unit of Vaughn
Member.

TAFT HILL MEMBER 19

Early Cretaceous (late Albian) affinities was collected
from near the base of the member between Great Falls
and Vaughn. The specimens that are lowest strati-
graphically (USGS Mesozoic loc. D3920, D4319, and
D4320) were collected approximately 4.2 m (14 ft)
above the base of the Taft Hill Member. This horizon
has yielded the following fauna:

Anomia n. sp.

I noceramus bellvuensis Reeside

Phelopteria sp.

A worm burrow

Two other collections made by Cobban (1951a,
p. 2179) in the N1/2 sec. 27, T. 21 N., R. 2 E., and in the
S1/2 sec. 10, T. 20 N., R. 2 E., from a horizon approxi-
mately 3 m stratigraphically higher, include the fol-
lowing:

Discinoid brachiopod

I noceramus cf. L. caddottensis McLearn
Inoceramus sp.

Phelopteria cf. P. salinaensis (White)
Anchura cf. A. quitmanensis Stanton
Fragment of a smooth compressed ammonite

This same zone crops out below the equivalent of the
middle unit, the glauconitic sandstone, in a very lim-
ited area in the SE. cor. SEIASWIA sec. 17, T. 17 N.,
R. 1 E. Collections by C. E. Erdmann and K. S.
Soward contained the following fauna:

USGS Mesozoic loc. D2931 (upper bed):
Lingula cf. L. subspatulata Hall and Meek
Ostrea anomioides Meek
Ostrea larimerensis Reeside
Trigonia Sp.

Cardium kansasense Meek
Callistina? belviderensis (Cragin)?
Cyrena? dakotensis Meek?

USGS Mesozoic loc. D2930 (lower bed):
Lingula cf. L. subspatulata Hall and Meek
Phelopteria sp.

Anomia sp.
Trigonia sp.
Anchura sp.

The middle unit (glauconitic sandstone) of the Taft
Hill Member appears not to contain any fossil mol-
lusks; at least none have been found. But a broken
isuroid shark tooth, generically and specifically inde-
terminate, and a small (10 by 12 by 27 mm) striated
coprolite were collected from near the base of the unit
at Vaughn junction. The explanation for the absence of
a marine molluscan fauna in this unit and other glau-
conitic facies of the Taft Hill is believed to be related to
the chemical character of the water in which they were
laid down. The sea at that time probably was brackish,
with a low concentration of calcium carbonate and a
seasonally variable pH value centering around 7.5.

 

Hence, sufficient CaCO3 may never have accumulated
for marine animals to make shells, or, if they did, sub-
sequent lower concentrations or increases in acidity
(lower pH values) might have caused the carbonate to
go back into solution.

Fossils consisting of the long-ranging pelecypod gen-
era N ucula, N uculana, and Lucina were found in the
upper part of the member in soft silty gray shale ex-
posed in a streambank 3.2 km (2 mi) north of Vaughn
in the NW%SW%NW% sec. 7, T. 21 N., R. 2 E. (USGS
Mesozoic loc. D529). Also, as noted previously, the
brachiopod Lingula subspatulata Hall and Meek has
been reported from the uppermost bed of the type
section.

The best dating for the lower part of the Taft Hill
Member has been from collections made by M. R.
Mudge at the Rocky Mountains front, on Sun River,
about 92 km (57 mi) west of Vaughn. There, Mudge
(1972, p. A62—A63) collected Inoceramus comanchean-
us Cragin and other marine pelecypods and gastropods
of late Albian age from many levels. Both 1. coman-
cheanus Cragin and I. bellvuensis Reeside also have
been reported by Stelck (1958, p. 3) from the Joli Fou
Shale in northern Alberta, but, unfortunately, their
position with respect to the Spinney Hill Member,
which may not have been present there, is not stated.
In the United States, these fossils indicate a correla-
tion with at least part of the Skull Creek Shale of the
Black Hills region and the Kiowa Shale of Kansas.
Evidently they indicate a normal shallow-water ma-
rine environment. The strata containing I. coman-
cheanus Cragin on Sun River have not been correlated
with the type section, so the stratigraphic relationship
of the fossiliferous beds to the middle unit, the glaucon-
itic sandstone, is not known in Montana either. There
is some reason to believe, however, that they may be
equivalent to the lower part of the member, or even
somewhat older, since it is possible to show that some
of the upper part of the Taft Hill may be early late
Albian in age.

Cobban (1951a, p. 2177) originally considered the
beds herein assigned to the middle unit of the Taft Hill
Member as “the probable equivalent of the Newcastle
sandstone” of the Black Hills, inasmuch as both units
overlay black shale of Skull Creek age (late Albian).
Mudge’s recent discovery of late Albian fossils in the
Taft Hill equivalent west of Vaughn suggested the pos-
sibility that the member as a whole represents an
inner sublittoral facies of the upper part of the Skull
Creek Shale. The Cyprian Sandstone Member at the
middle of the Thermopolis Shale in the Little Rocky
Mountains of north-central Montana also has been
suggested as a Newcastle Sandstone equivalent by
Knechtel (1959, p. 740). When referred to the base of

20

the Colorado Group (top of Kootenai Formation), the
base of the Cyprian Sandstone Member, which is about
7.6 m (25 ft) thick, occupies approximately the same
stratigraphic level as the thin littoral conglomerate
(bed 31, type section), 5.1 m (16.6 ft) below the top of
the Taft Hill Member. Although no direct correlation
has been established between these two units, this cor-
respondence of horizon is roughly suggestive of equiva-
lence. There also is noticeable similarity in the ap-
pearance of their chert pebbles. The sandstones at the
top of the Taft Hill, therefore, may likewise be equiva—
lent to the Newcastle Sandstone.

Knechtel (1959, p. 740) also pointed out that the
Cyprian Sandstone Member "is considered to be equiv—
alent to the Viking Sandstone of southern Alberta and
Saskatchewan, Canada.” The Viking Sandstone over-
lies the Joli Fou Formation in eastern Alberta and
west-central Saskatchewan, and the probable correla-
tion of the glauconitic Spinney Hill Member of the Joli
Fou with the middle (glauconitic sandstone) and lower
units of the Taft Hill has been suggested. According to
Stelck (1958, p. 3), the “Viking sandstone belongs to
the base of the upper Albian substage near the top of
the Lower Cretaceous,” but in his correlation chart
(1958, fig. 1, p. 4) it has been placed somewhat higher,
with the Joli Fou Formation at the base of the upper
Albian, overlapping slightly into the upper part of the
middle substage of the Albian.

DESCRIPTIVE SECTIONS OF TAFT HILL MEMBER

The following descriptions of type and reference sec-
tions of the Taft Hill Member of the Blackleaf Forma-
tion are based primarily upon field descriptions. Only a
few representative specimens have been studied pet-
rographically and mineralogically. In order to make
the two described sections as comparable and comple-
mentary as possible, each section has been subdivided
into three units. Cross-reference within the bed de—
scriptions and to the text have been used where iden-
tification of individual beds seems important.

Type section of Taft Hill Member

[Composite section from measurements by R, W. Lemke and E. K, Maughan at four local—
ities south and southeast of Vaughn in the Great Falls and Vaughn Quadrangles. Units
2-6 were measured in the center of sec. 9, T. 20 N., R. 2 E.; units 7713 in SE‘A sec. 2, T. 20
N., R. 2 E.; unit 14 on south bank ofSun River in the SW‘A sec. 25, T. 21 N., R. 1 E.; and
units 1&35 in the SW‘ASEI/a sec. 1, T. 20 N., R. 1 E. (fig. 7)]

Blackleaf Formation:
Vaughn Member (entire member exposed at this 10-
cality but only basal bed described here):

35. Sandstone, light—gray to buff, poorly consoli-
dated, friable to platy. Lower third is cal-
careous and contains carbonized plant
fragments; rest of unit is noncalcareous,
slightly bentonitic near base, and weathers
yellowish orange. Platy beds are fine to

 

BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

C
_.
I
o
l—
o
‘2
O

SYMBOLS

Middle unit

(I)
(I) m
s 3
z: %
o H

O
3 :7
m m

 

Shale
@Q
9 e

Calcareous
concretions

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

HEIDI]
C
3: 3
C i. .
J a) Bentonlte
n i
u) o
o. _l
a E
3
Carbonaceous
shale
METRES FEET
o ——— o
—# 20
— 40
R. 1 E —— 60
20 —
1 2 3 MILES
1 2 3 4 KILOMETRES
R. 2 E
5 4 3 1
S
2,»-
B -‘
8 2.6-. 10 11 12

 

 

 

 

 

 

 

 

 

 

FIGURE 7.—Type section of the Taft Hill Member of the Blackleaf
Formation and map showing line of measured section, secs. 2 and
9, T. 20 N., R. 2 E., sec. 1, T. 20 N., R. 1 E., and sec. 25, T. 21 N., R.
1 E. Numbers on the left side of the column are key beds in the
measured section. On the map, the arrow points upward strati-
graphically; B, base, and T, top of member.

TAFT HILL MEMBER

Type section of Taft Hill Member—Continued

Blackleaf Formation—Continued
Vaughn Member—Continued
35. Sandstone, etc—Continued
medium grained, calcareous, and locally
crossbedded; these thicken northward into
massive crossbedded sandstone. Top of bed
forms a flat conspicuous bench 30-60 m
(100—200 ft) wide ________________________
Taft Hill Member:
Upper unit:

34. Sand, light-olive-gray, glauconitic, fine-
grained, slightly bentonitic; weathers light
yellowish gray; contains carbonaceous
fragments and locally numerous small
brachiopod (Lingula) shells. At top and 2 m
from base are lenses of platy light—olive-
gray (5Y 6/1) to greenish-gray (SGY 6/1)
glauconitic sandstone that weather
purplish gray __________________________

33. Sandstone, light-gray, fine-grained, thin-
bedded, well-jointed; weathers light bluish
gray; top of bed forms a ledge

32. Sand, slightly bentonitic; contains thin
lenses of black carbonaceous materialh"

31. Sandstone, pale-olive (10Y 6/2); fine- to
coarse-grained, calcareous, finely stratified
to massive, welljointed (N. 72° W.); weath-
ers dark greenish gray. Composed largely
of poorly sorted well—rounded to sub—
rounded grains of clear and smoky quartz,
dark chert, and undetermined green
grains, as well as some black chert pebbles
and abundant fish teeth and bones _______

30. Claystone, chiefly very light gray and buff,
silty to sandy, fine-grained, slightly ben-
tonitic; contains thin siltstone layers near
top. A few brown-weathering calcareous
concretions that have cone-in-cone struc-
ture are 2 m above base _________________

29. Siltstone, olive-brown, bentonitic, soft.
Weathered surface is spongy and medium
gray mottled with yellow. At base are a few
calcareous concretions that have cone—in-
cone structure ,,,,,,,,,,,,,,,,,,,,,,,,,,

28. Shale, light-olive—gray, silty, indistinctly fis-
sile, slightly calcareous; outcrop weathers
to conspicuous grayish white (fig. 6) and
can be traced for many kilometres. Locally
contains hard thin siltstone layers and
ovoid to round calcareous siltstone or argil-
laceous limestone concretions about 1 m in
diameter; these concretions, light greenish
buff on fresh fracture, weather to rounded
nodules that are grayish buff mottled with
dark brown ,,,,,,,,,,,,,,,,,,,,,,,,,,,,

27. Bentonite, greenish-yellow, impure; forms a
lightvgray spongy bench ________________

26. Siltstone, light-gray, glauconitic, moder-
ately well bedded; weathers light bluish
gray; consists chiefly of subangular frosted
quartz grains with some hornblende and
glauconite. Contains carbonaceous frag-
ments along bedding surfaces. Few very

M Ft
6.2 20.3
3.1 10.2
1.1 3.6

.9 2.8
0.2 0.6
4.6 15.1
2.9 9.6
1.7 5.7

.7 2.2

 

21

Type section of Taft Hill Member—Continued

Blackleaf Formation—Continued
Taft Hill Member—Continued
Upper unit—Continued
26. Siltstone, etc—Continued
small crystals of red clinoptilolite in frac-
tures at top of unit. Here and there are
brown'weathering concretions that have
cone-in—cone structure __________________
25. Shale, dark-gray; fissile, slightly bentonitic;
becomes lighter gray and silty upward. At
base is a discontinuous bed of brown-
weathering limestone that has cone-in-
cone structure __________________________
24. Shale, nearly black, bentonitic, partly fissile;
weathers to a gray spongy slope. Includes a
lenticular brownish-weathering bed of
light-greenish-gray medium-grained
slightly friable calcareous sandstone that
contains a few grains of glauconite, horn—
blende, and mica ______________________
23. Bentonite, greenish-yellow, nearly pure;
forms spongy bench. Scattered irregularly
shaped gray siltstone concretions contain-
ing carbonaceous fragments. Forms a dis-
tinct spongy bench
22. Siltstone, dark-gray;
gray
21. Sandstone, fine—grained, bentonitic, soft; in—
terbedded with dark-gray bentonitic shale
and in upper 1 m iron-stained bluish-
gray-weathering siltstone ______________
20. Sandstone, olive-buff, fine-grained, distinct-
ly laminated, calcareous, bentonitic, soft;
weathers to spongy surface marked by
dark—gray bands, some of which are
stained orange
19. Sandstone, light-gray, mostly silty and fri—
able, massive, moderately calcareous; con—
tains brown—weathering concretionary
lenses of fine- to medium-grained gray cal-
careous sandstone through most of upper
two-thirds of bed. Top of unit is lenticular
bed as much as 24 cm thick of dark-gray
argillaceous limestone that weathers
brown and has indistinct cone-in-cone
structure _______________________________
18. Shale, bentonitic; weathers to light-gray
spongy surface. Lower part is dark gray
except for basal 0.6 m, which is nearly all
yellowish-green bentonite; limestone con-
cretions occur 1.8 m and 3.7 In (6 ft and 12
ft) above base. Upper part is distinctly fis-
sile and silty and weathers to a gray
spongy surface; a thin bentonite bed is 5.5
m (18 ft) above base _____________________
17. Cone-in-cone concretions, medium—dark-
gray, calcareous; weather brown; some as
large as 1 m in diameter ________________
16. Shale, bentonitic; weathers to a light-gray
spongy surface
15. Covered
Middle unit:
14. Sandstone, olive-green (10Y 5/2—10Y 5/4),
fine— to medium-grained, platy and friable

weathers bluish

M Ft
3 .9
1.5 5.0
4.1 13.5
7 2.3
2 .6
3.4 11.1
2.9 9.5
3.0 9.8
7.9 25.8
2 .6
2.4 8.0
1.2 4.0

22 BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

Type section of Taft Hill F ormation—Continued
Blackleaf Formation—Continued
Taft Hill Member—Continued
Middle unit—Continued
14. Sandstone, etc—Continued M Ft

to massive and well—cemented, locally

crossbedded; mostly quartz with abundant

glauconite, chert, and calcite; silty to shaly

near base. Unit weathers to rough irregu-

lar surfaces. An impure greenish-yellow

bentonite layer 18 cm thick lies 2.4 m (8 ft)

above base. Some very thin lenses of

black-weathering siderite occur about 0.5

m below top ____________________________ 9.1 30.0
Lower unit:
13. Covered ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4.3 140+

12. Concretions, dark—brown, highly fractured;
argillaceous and ferruginous limestone
about 10 cm thick and 30—60 cm in diame-

ter, showing prismatic structure ,,,,,,,, .2 .5
11. Covered ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, .9 3.0
10. Sandstone, olive-green, medium-grained,
glauconitic, friable, noncalcareous ______ 1.5 5.0
9. Siltstone, bluish-gray, friable ............ 0.6 2.0
8. Siltstone, gray, clayey, partly fissile; a few
bentonite beds 3—6 cm thick ............ 1.4 4.5
7. Shale, black, fissile; a few bentonite beds 3—6
cm thick ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4.4 14.5

6. Sandstone, dusky-yellow (5Y 6/4), medium-
grained, well—sorted, porous, friable, indis—

tinctly laminated, slightly glauconitic-__- .6 2.0
5. Shale, grayish-yellow, sandy, bentonitic,

poorly exposed ........................ .9 3.0
4. Shale, black, distinctly fissile; includes a few

beds of bentonite about 3 cm thick ______ 6.1 20.0
3. Bentonite, greenish-yellow ________________ .6 2.0
2. Shale, black, fissile ______________________ __.3_ 1.0

Total Taft Hill Member (rounded) "e- 74 242

Flood Member (top):
1. Sandstone, light-gray, poorly exposed; weath-
ers tan __________________________________ 3.7+ 120+

Composite reference section for approximately the lower half of the
Taft Hill Member

[Measured by C. E. Erdmann, Oct. 1962 and May 1967, along US. Interstate 15 northwest
of Great Falls between the S‘a sec. 36, T. 21 N., R. 2 E., and Vaughn junction (sec. 19, T.
21 N., R. 2 EL), Cascade County, Mont. Beds 7&82 were measured along Manchester exit
road between secs. 26 and 25, T. 21 N., R. 2 E.; beds 77753 were measured in the center of
sec. 19, T. 21 N., R. 2 E; beds 52—35 were measured in the NE‘ASE‘A sec. 19, T. 21 N., R. 2
15].; beds 34~19 were measured in the NE cor. NW%SW% sec. 26, T. 21 N., R. 2 E.; and beds
1&1 were measured in the NE%NW‘/4 sec. 36, T. 21 N., R. 2 E.]

M Ft
Pleistocene:
Pre-Wisconsin. Terrace gravels along the Sun River
consisting chiefly of argillite and quartzite from the
Belt Supergroup; lime coated, loosely consolidated
in a sandy matrix 111111111111111111111111111111 2.1 7.0
Unconformity.
Blackleaf Formation:
Taft Hill Member:
Upper unit:
82. Siltstone, soft; weathers rusty ____________ .6 2.0
81. Bentonite, light-gray, soft, weathered 111111 .1 .3
80. Siltstone, medium-light-gray; weathers
rusty __________________________________ 3.1 100

 

Composite reference section for approximately the lower half of the
Taft Hill M ember—Continued
Blackleaf Formation—Continued
Taft Hill Member—Continued
Upper unit—Continued M Ft

79. Bentonite, light—yellowish-gray ............

78. Siltstone, medium-light-gray, soft, fissile;

contains a few thin limonitic laminae.

Base darker (N 3), with 0.6-cm-thick

laminae of light-olive-gray shale at inter-

vals of about 3 cm ______________________ 2.7 9.0

,_.
'co

Diastem(?)
Middle unit (the glauconitic sandstone):

77. Sandstone, olive-gray, fine-grained; thin
0.6-cm horizontal wavy layers. Top irregu—
lar with local relief of 50 cm ____________ .2 .5

76. Sandstone, light-olive-gray, fine—grained.
Top irregular and marked by a thin film of
dark-gray sandy clay (graded bedding?)
Below this upper 15 cm there is exhibited
planar (“torrential”)-type cross-lamination
with true dip 20° S. to 11° E. Bedding in
lower 10 cm essentially horizontal.
Homogeneous (nonlaminated) layers are

here and there calcareous .............. 2 .8
75. Sandstone, light-olive—gray, fine-grained.

Upper half cross-laminated with 2-

cm-thick beds dipping 20° S. to 15° W.

(component dip?); lower part massive, with

thin horizontal laminae ................ .3 1.0
74. Sandstone, light—olive-gray, thin, soft, fri-

able __________________________________ 1 .3

73. Sandstone, light-olive—gray, fine-grained,

firm; consists of moderately resistant 5- to

15-cm-thick layers. 15-cm-thick bed, in

middle, has 0.6-cm-thick laminae in

planar-type cross—lamination dipping

15° S ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, .6 2.1
72. Sandstone, light-olive-gray, fine-grained.

Top marked by horizontal laminae of

dark-gray silty shale. Lower 15 cm has

0.6-cm—thick sandstone laminae in

planar-type cross-lamination dipping

15° S __________________________________ .2 .8
71. Sandstone, light«olive-gray, fine-grained;

weathers dusky yellowish brown to dark

yellowish brown in scabby ferruginous

crusts 0.3—0.6 cm thick. Locally

persistent ______________________________ .1 .3
70. Sandstone, light—olive—gray, finevgrained; in

5-cm-thick noncalcareous layers. Softer

than underlying bed ____________________ .6 2.0
69. Sandstone, light-olive-gray, fine-grained,

calcareous, hard, resistant; makes a thin

ledge on freshly cut slope. Base irregular.

Locally persistent ______________________ .2 .7
68. Sandstone, light—olive-gray, fine-grained; in

thin 1- to 5-cm soft friable layers. Top 10—

cally undercut __________________________ .4 1.3
67. Shale, light-olive—gray (5Y 5/2), soft, finely

laminated, fissile; weathers dusky yel-

lowish olive to dark yellowish orange ”-1 .1 .2
66. Sandstone, olive-gray, medium-grained,
thinly laminated, soft, glauconitic ______ .1 .4

65. Clay ironstone, compact aphanitic to sandy,

Composite reference section for approximately the lower half of the

Taft Hill Member—Continued

Blackleaf Formation—Continued
Taft Hill Member—Continued
Middle unit, etc—Continued

65. Clay ironstone, etc—Continued

64.

63.

62.

61.

60.

59.

58.

57.

56.

55.

hard, brittle; more or less completely
weathered through with dark-yellowish-
orange concentric structures; surface
commonly brownish black with manganese
oxide stain and fine-textured botryoidal
forms; contains short thin lentils of loosely
consolidated glauconitic sand that weath-
ers out to leave small flat elliptical
cavities. A broken isuroid shark tooth and
a small (10 by 12 by 27 mm) striated copro—
lite have been found on surface of bed. Lo-
cally persistent ________________________
Sandstone, light-olive-gray, fine- to
medium-grained; in soft friable horizontal
5-cm-thick layers ______________________
Sandstone; as above, as 5-cm-thick layers
with laminae of detrital glauconite. Casts
of trace fossils on bedding surfaces. Top
marked by thin film of olive-gray (5Y 4/1)
fissile shale; 15—cm-thick upper bed
exhibits planar cross-lamination dipping
10°—12° S. 10° W. Makes an indistinct
ledge __________________________________
Sandstone, light-olive-gray, fine-grained,
glauconitic; softer and more friable than
underlying bed; bedding indistinct ______
Sandstone, light-olive—gray, fine-grained,
glauconitic. Upper half soft; lower half
firm, calcareous ,,,,,,,,,,,,,,,,,,,,,,,,
Sandstone, as immediately above; contains
epigenetic banded crusts 0.6—1 cm thick of
very dusky red clay ironstone in lentils 10
cm long and 3 cm thick, which are espe-
' cially well developed in lower part ______
Sandstone, light-olive-gray, fine-grained,
glauconitic; more thinly bedded than
above. Entire sequence makes indistinct
ledge __________________________________
Cone«in-cone calcite, light- to medium-gray;
occurs as radiating fibers in asymmetric
brushlike aggregates 3—8 cm long replac—
ing yellowish-gray bentonite, some of
which remains intergrown at point (base)
of cones. Contains 0.6-cm-thick crusts of
very fine fibrous yellow-brown calcite with
silty luster ____________________________
Cone—in-cone calcite; weathers dark yellow-
ish orange. More massive than overlying
bed, into which it grades ________________
Sandstone, light-olive-gray, hard, massive,
calcareous; grades upward into fine-
grained bentonitic sandstone that weath-
ers dark yellow orange. Entire sequence
very distinct, locally persistent, making a
valuable marker bed ____________________
Sandstone, light-olive-gray, glauconitic,
fine-grained; in 3- to 20-cm-thick layers
separated by softer more finely laminated
partings. Slightly irregular bedding sur-
faces are marked by thin laminae of detri-

TAFT HILL MEMBER

1.0

0.2

Ft

2.2

2.0

3.2

0.5

 

Composite reference section for approximately the lower

half of the Taft Hill Member—Continued
Blackleaf Formation—Continued
Taft Hill Member—Continued
Middle unit, etc.—Continued

55.

54.

53.

52.

51.

50.

49.

48.

Sandstone, etc—Continued
tal glauconite which show trace fossils
(worm trails?) and other markings ______
Siltstone, olive-gray, soft; transitional into
bed above ______________________________
Bentonite, light—yellowish-gray (5Y 8/1), tuf-
faceous, firm, compact; weathers light yel-
lowish orange. Breaks with flat subcon-
choidal fracture. Thickens and thins ____
Sandstone, olive-gray, glauconitic. Lower
part is shaly and thinly laminated with
medium—dark-gray shaly partings weath—
ering light olive gray __________________
Sandstone, olive-gray, glauconitic. Top
makes weak ledge. Lower part is thinly
laminated, with partings of soft medium-
dark-gray fissile shale that weathers light
olive gray ______________________________
Sandstone, light-olive-gray, fine- to
medium-grained, glauconitic; upper part
makes protruding ledge ________________
Sandstone, olive-gray, fine-grained, silty,
soft ____________________________________
Sandstone. Upper 30 cm is light olive gray,
fine grained, less silty, noncalcareous, but
firm and resistant, and forms lowest ledge
marker of middle unit. Lower 18 cm is soft-
er, weathers into rounded form by spalling
corners off joint blocks. This is the basal
bed of the glauconitic sandstone. Can actu-
ally be seen to wedge out to the east with
base stepping upward __________________

Measured thickness of middle unit 11,-

Lower unit:

47.

46.

45.

44.

43.

42.

41.

40.

39.

Sandstone, light-olive—gray, glauconitic,
fine-grained, silty, soft, friable. Stratifica-
tion marked here and there by thin
rusty-weathering bentonitic(?) laminae -_

Bentonite; upper part is clayey, light olive
gray (5Y 5/2), and weathers dark yellowish
orange. Lower part is more bentonitic, is
light yellowish gray, soft, and weathers
dark yellowish orange __________________

Sandstone, light-olive-gray (5Y 5/2), glau-
conitic, fine-grained, silty, soft, friable.
Traces of thin laminae of olivevgray shale

Sandstone, olive—gray, clayey ____________
Bentonite, soft, silty; weathers grayish
orange ________________________________
Sandstone, olive-gray, clayey; weathers

downward into thin scales. Contains two or
three thin (0.6 cm) bentonite beds 111111
Bentonite, light-olive-gray, soft, clayey.
Base sharp and distinct; top gradational
Sandstone, pale-olive-gray; 5-cm (2—in.)-
thick layer of soft dark-olive-gray clayey
silt at base ____________________________
Bentonite, dark-yellowish-orange, com-
pletely weathered, soft, flakey. Base sharp;
top gradational ________________________

la

j.

(X)
{D

H-

1.1

23

Ft

2.7

1.0

1.3

be

M
(DH
[00}

ll-

'0:

2.2

3.5

24 TAFT HILL MEMBER
Composite reference section for approximately the lower half of the Composite reference section for approximately the lower half of the
Taft Hill Member—Continued Taft Hill Member—Continued
Blackleaf Formation—Continued Blackleaf Formation—Continued
Taft Hill Member—Continued Taft Hill Formation—Continued
Lower unit—Continued M Ft Lower Unit—Continued

38. Sandstone, pale—olive—gray, glauconitic 11,, .3 .9 28. Siltstone, etc—Continued M Ft

37 Bentonite, light-yellowish-gray t0 grayish— intervals of 9—15 cm by many short lentils
orange, soft, fissile. Base sharp; top grada- of finely laminated fine-grained light-
tional 7777777777777777777777777777777777 .1 .2 olive-gray sandstone ____________________ 1,1 3.7

36. Sandstone, pale-olive—gray, glauconitic, 27. Bentonite, light-yellowish-gray; weathers
fine-grained, silty, soft, friable, poorly con- rusty at base and top __________________ .1 .2
solidated. Very homogeneous; indistinct 26. Siltstone, medium-dark-gray; contains short
bedding marked by thin laminae of bento- thin lentils of intraformational microcon-
nite __________________________________ 0-9 3-0 glomerate in a matrix of light-medium-

35. Interval concealed ______________________ 1.1 3.5 gray fine-grained calcareous sandstone

34. Bentonite, very light yellowish to greenish- that weathers light olive gray. A more or
olive-gray, soft, weathers dark yellowish less persistent layer 3—6 cm thick contain-
orange; clayey, with waxy luster. Top gra- ing fragments of Inoceramus occurs in
dational ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, .1 .3 middle of unit. A very thin olive-brown

33. Siltstone, medium-dark—gray, soft, fissile. fine» to medium—grained poorly sorted
Weathered surface shows numerous thin sandstone layer at base contains fragments
translucent sheets and films of secondary of very dark gray carbonaceous mudstone
selenite eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee .8 2.5 and impressions and fragments of In-

32. Sandstone, olive-gray to moderate—olive- oceramus ______________________________ .7 2.3
brown, fine- to medium-grained, cherty, 25. Siltstone, medium-dark-gray, soft, flaky;
glauconitic, soft, noncalcareous; matrix some laminae weathering olive gray ____ .9 3.0
of dusky-yellow silt; contains thin fiat- 24. Vitric crystal tuff, very light gray to light-
tened galls of medium-dark-gray siltstone yellowish—gray, partially devitrified, firm,
as much as 3 cm across. Top marked locally compact, porous; cutting easily, but
by a thin layer of very fragile light-brown slightly more resistant than enclosing
Inoceramus prisms. Estimated percentage siltstone; weathering or stained dark yel-
composition of sand fraction: subangular lowish orange at some localities. Very fine
quartz, 60, with yellowish-gray dust from grained, breaking with subconchoidal frac-
matrix; chert, dark gray to black, subangu- ture; largest crystal fragments range from
lar to subround, unpolished, 25; glauconite about 0.007 to 0.155 mm ................ .1 .2
(first appearance in Taft Hill Member), 23. Siltstone, medium-dark-gray; some laminae
dusky yellowish green, smooth ovoidal or weather light olive gray; very thin light-
lobate grains and compound spherical gray layer of bentonite near base ________ .3 1.1
masses ranging in diameter from 0.5 to 1.3 22. Sandstone, light-gray, fine-grained, cherty;

mm, loosely embedded in the sandstone calcareous cement; soft and friable where
but not in the clay galls; nondetrital, auth- weathered. Occurs in thin (3 cm) short len-
igenic (diagenetic), but with afew irregu- tils. Locally, a thin (3 cm) rusty-
lar intergranular masses as much as 2 cm weathering bentonite at base ____________ .2 .6
across; accessory muscovite, rare ________ .3 1.0 21. Siltstone, medium-dark-gray, soft, fissile; a

31. Siltstone (mudstone), medium-dark—gray; few rusty laminae —————————————————————— -4 1-2
contains scattered concretions of light- 20. Bentonite, light-gray (grayish-white), 80ft,
yellowish-gray calcite with cone-in-cone clayey; weathers dark yellowish orange;
structure; weathers brownish gray to base locally irregular __________________ .4 1.2
dusky red, in very complex intergrowths 19. Shale, medium-dark-gray, fissile __________ 1.1 3.6
with mudstone. Individual masses as much 18. Sandstone, medium-gray, fine-grained,
as 1 m long and spaced variably at inter- clayey, calcareous. Contains a few thin
vals of 3—15 m. Lower surface of concre— granules of polished brownish-gray chert
tions is irregular, cutting across bedding. as much as 3 mm in diameter, and clay-

Where cone-in—cone structure has not de- stone pellets 3 by 6 cm and 1 cm thick.
veloped, base of unit may contain flat oval Flute casts on base; bedding irregular; top
masses 5 by 20 cm of massive olive-gray irregular, With ripple marks in places in a
calcareous siltstone that contain frag- thin film 0f brown ferruginous sandstone
ments ofInoceramus ,,,,,,,,,,,,,,,,,,,, .2 .5 with wavelength of 6 cm and amplitude of

30. Siltstone, medium—dark-gray ,,,,,,,,,,,,,, .2 .5 1 CID. Worm tubes filled with gray clay -_ .1 .3

29. Bentonite, light-gray, soft, clayey; in local 17- Shale, medium—dark-gray; weathers YUSW
lenses, some of which show a thin basal brown along sandy laminae eeeeeeeeeeee 2 -6
layer of very light gray vitric tuff ______ .1 .2 16. Sandstone, light-gray, fine-grained, noncal-

28_ Siltstone, medium-dark-gray; locally shows careous. In short lentils ———————————————— ~2 -7
thin olive laminae in upper 30 cm. Middle 15- Shale, dark—gray, poorly exposed "a. rrrrrrr .3 1-0
and lower part characterized at vertical 14. Shale and sandstone; in thin layers. Sand-

 

VAUGHN MEMBER 25

Composite reference section for approximately the lower half of the
Taft Hill Member—Continued
Blackleaf Formation—Continued
Taft Hill Formation—Continued
Lower unit—Continued
14. Shale and siltstone, etc—Continued M Ft
stone is light medium gray and fine
grained; shale is medium dark gray --__ .1 .3
13. Sandstone, conglomeratic, medium-light-
gray, calcareous, hard; firm and compact
when fresh; weathers light yellowish
brown in places. In finely laminated lenses
of variable thickness and width separated
by thinner irregular partings of soft olive
clay. Sand facies or matrix fine to medium
grained, subangular, and with salt-and-
pepper appearance. Conglomeratic facies
characterized by usually small (2 mm or
less) rounded granules and pebbles of
brownish and dark-gray chert; also charac-
terized by subrounded granules as much as
5 mm in size of very light gray yellowish-
gray to white aphanitic tuff. Percentages
vary, but chert and tuff combined may
make about 40 percent, and when about
equal give the rock a very distinctive ap
pearance. Fish scales and vertebrate bones
are rare as accessories ------------------ .1 .4
12. Sandstone, light-gray, calcareous, hard,
firm; makes a weak ledge -------------- .2 .6
11. Sandstone, olive to light-yellowish-gray, fine
grained, soft; weathers rusty brown in
places. Occurs in thin (0.5—1 cm) lentils
separated by thin partings 0f dark'gray
clay
10. Shale, medium-dark-gray, clayey, soft, plas-
tic. Less fissile than that just below ------ .4 1.4
9. Shale, medium-darkgray, fissile, papery;
thin layer of fine-grained sandstone
at top ---------------------------------- .3 1.1
8. Clay, dark-gray, soft. Contains thin laminae
of fine-grained rusty sandstone ---------- .2 .6
7. Sandstone, fine- to medium-grained. In
small lentils or pods -------------------- .1 .2
6. Clay, sandy, but soft and plastic; olive-gray
when moist. Contains here and there
brown-weathering concretions of calcare-
ous olive mudstone 60 cm in diameter and
13 cm thick, with a layer of cone-in—cone
structure on top ________________________ .1 .4

Intramember erosional disconformity.
5. Sandstone, medium-gray, calcareous, hard;
weathers brownish gray; makes ledge; fine
to medium grained, with a sprinkling of
small granules of dark chert cemented by
authigenic crystals of calcite. Top slightly
irregular; rusty brown __________________ 5 1.7

Thickness of partial section of Taft Hill
Member (rounded) __________________ 31
Erosional disconformity.
Flood Member:
4. Sandstone, yellowish-gray, medium-grained,
subangular, weakly cemented, friable; good
porosity and permeability; predominantly

 

Composite reference section for approximately the lower half of the
Taft Hill Member—Continued
Blackleaf Formation—Continued
Flood Member—Continued
4. Sandstone, etc—Continued M Ft
clear glassy quartz whose crystal faces glisten
brightly, with about 5 percent yellowish-gray
weathered feldspar and 5 percent dark min-
erals (chert) ------------------------------ 1.1 3.4
3. Sandstone, yellowish-gray, fine- to medium—
grained (as above). Largely concealed by rub-
ble -------------------------------------- 4.9
2. Sandstone, yellowish-gray; as above, with a few
small spherical concretions of orange—brown
limonitic sandstone. Top makes resistant
ledge ____________________________________ 2.6 8.5
1. Sandstone, medium—gray, fine-grained; in short
lentils or nodules separated by thin partings

16.0

of medium-gray siltstone and shale -------- . 2.0+
Thickness of partial section of
Flood Member (rounded) -------------- 9.0 30.0

VAUGHN MEMBER
NAME AND DEFINITION

Strata of the Vaughn Member of the Blackleaf F or-
mation were formerly referred to as the “red speck
zone” (Erdmann and Schwabrow, 1941, p. 284; Blixt,
1941, p. 337) and the "nonmarine member” (Cobban,
1951a, p. 2180). Later, in subdividing the Colorado
Group, the strata were called the Vaughn Bentonitic
Member of the Blackleaf Formation by us (Cobban and
others, 1959, p. 2790) with the intent of including rocks
of nonmarine origin between the Taft Hill Glauconitic
Member below and the Bootlegger Member above. As
first measured by us (Cobban and others, 1959) and
illustrated by Maugham (1961), the type section of the
member included transitional beds at the base that are
only locally present. These strata are now believed to
be of marine origin and have been assigned to the Taft
Hill Member in this paper. The Vaughn Member by
definition is exclusively continental in origin.

The Vaughn Member is named from excellent expo-
sures north and south of Vaughn, 19 km (12 mi) west of
Great Falls. The type section crops out along the east
bank of an unnamed intermittent wash in the N1/2NE14
sec. 6, T. 21 N., R. 2 E., and on a southwest-pointing
spur in the SEIASWMiSEMi sec. 31, T. 22 N., R. 2 E.
(Vaughn quadrangle) (fig. 8). This locality is somewhat
inaccessible in that it cannot be seen or quickly
reached from any main road. The easiest approach to it
is over an unsurfaced road from the north and down an
abrupt escarpment between secs. 31 and 32, T. 22 N.,
R. 2 E., to the NE. cor. sec. 6, T. 21 N., R. 2 E.; from
there it is about a 0.8-km (0.5 mi) walk to the west. For
greater accessibility, a composite reference section of
the member designated in this report has been meas-
ured and described in detail 4 km (2.5 mi) to the

26 BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

 

FIGURE 8.-Type section of the Vaughn Member about along the center line of the NEM; sec. 6, T. 21 N., R. 2 E., Cascade County,
Mont. The sandstone cropping out in the upper middle part of the photograph below the light-gray bentonitic unit bare of vege-
tation marks the base of the member. R. W. Lemke is standing on a limestone bed 8.5 m (28 ft) below the top of the Taft Hill
Member.

southwest, along US. Highway 91 (Interstate 15), in
the NE% sec. 11 and SEM; sec. 2, T. 21 N., R. 1 E.

THICKNESS

In its type section the Vaughn Member has a thick-
ness of approximately 26 In (86 ft). As first defined
(Cobban and others, 1959, p. 2790), the thickness given
was 29.6 m (97 ft), but this thickness included underly-
ing probable marine strata now assigned to the Taft
Hill Member. The thickness in the composite reference
section, about 4 km southwest, is 26 m (86 ft). In an
outcrop 17.7 km (11 mi) east (escarpment north of
Blackhorse Lake Flat east of the Bootlegger Trail, 11.2
km or 7 mi north of the city of Great Falls), the thick-
ness has decreased to 15.9 m (52 ft). The member con-
tinues to thin to the southeast toward Belt Butte,
where its thickness is only 7.9 m (26 ft) in sec. 30, T. 19
N., R. 7 E. The increase in thickness to the west, how-
ever, is more rapid. Schmidt (1963) assigned 114 m
(375 ft) of strata to the member in the Wolf Creek area;

 

south of the town of East Glacier, Vaughn lithology
seems to have completely replaced the Taft Hill
Member and the Bootlegger Member.

s Although not commonly recognized in old cable-tool
drillers’ logs, some part of the Vaughn usually can be
identified microscopically in formation samples, and it
serves as a general marker for the middle part of the
Blackleaf Formation. No part of it, however, provides a
satisfactory datum for regional structural mapping.
Thicknesses in the subsurface on the Sweetgrass arch
seem not to be so systematic in their range as those in
outcrops. A number of factors, singly or in combina-
tion, probably contribute to this condition: (1) The
internal character of the boundaries changes from
place to place in consequence of the variable continen-
tal lithology; (2) the top may be affected by a slight
erosional disconformity, with some variation in the
overlying units; and (3) local absence of the diagnostic
mineral clinoptilolite. Apparently some anomalous
thicknesses result from disaggregation and "washing

VAUGHN MEMBER

out” of montmorillonite from the claystone. For these
reasons the top of the member is not a good datum
plane for regional structural mapping.

The Vaughn is 45 m (150 ft) thick in the Brady oil
field, 69 m (227 ft) thick near the west edge of the
Pondera oil field, 22 m (74 ft) thick at the top of the
Kevin-Sunburst dome (sec. 15, T. 34 N., R. 1 W.), 37 m
(120 ft) thick on the west side of the Cut Bank oil and
gas field (sec. 13, T. 35 N., R. 6 W.), and 160 In (525 ft)
thick in the Chicago Petroleum Corporation’s Mabel
Armstrong Well 1 Allotted 168 in sec. 35, T. 36 N.,
R. 8 W. The member thins eastward from the Kevin—
Sunburst dome and has not been recognized east of the
Sweetgrass Hills.

OL'TC R0 1’ DISTR 1B UTION

On the Sweetgrass arch the Vaughn Member crops
out only on the southern part of the South arch. Begin-
ning with the outcrops along the Missouri River in the
northeastern part of the Portage quadrangle, the belt
of outcrop extends southwestward across that quad—
rangle to the Blackhorse Lake Flat area, 8—13 km (5—8
mi) north of the city of Great Falls. From Blackhorse
Lake Flat, the belt of outcrop trends slightly north of
west and crosses the Great Falls quadrangle just be-
low its middle. The outcrop continues west into the
Vaughn quadrangle and up Muddy Creek to a point in
the SE14 sec. 32, T. 22 N., R. 1 E., where it dips below
the valley floor. Along the Sun River the member is
exposed from a point 1.6 km (1 mi) west of Vaughn on
up the valley for 9.6 km (6 mi) to the southern part of
sec. 36, T. 21 N., R. 1 W., where the top disappears
below the river. South of Vaughn the member is very
well exposed along the east side of Taft Hill and
southward through the Cascade quadrangle. The out-
crop crosses the Missouri River at Riverdale and con-
tinues south up Bird Creek valley for 16 or 17 km.

West of the South arch the Vaughn Member is ex-
posed at many localities in the Disturbed belt from 3.2
km (2 mi) northeast of Wolf Creek in sec. 31, T. 15 N.,
R. 3 W., northwest to the southeast boundary of
Glacier National Park, where the Vaughn has com-
pletely replaced the Bootlegger Member.

GENERAL DESCRIPTION

Light-colored bentonitic clay, siltstone, and
sandstone largely compose this member. Most of the
rocks are soft and readily erode into poorly vegetated
badlands that are conspicuous in the Cascade, Vaughn,
Great Falls, and Portage quadrangles (Cobban, 1955a,
fig. 2).

In the type section northeast of Vaughn (fig. 8), the
basal unit of the member consists of 4.6 m (15 ft) of
pale-greenish-yellow medium-grained very friable ar-

 

27

kosic sandstone. At a locality 13 km (8 mi) to the south,
along a road ascending Taft Hill, in the SE%SW%
sec. 7, T. 20 N., R. 2 E., the base ofthis sandstone bed is
coarse grained, contains some gray shale pebbles, and
is channeled into the underlying fine-grained
glauconitic sandstone of the Taft Hill Member. This
basal sandstone bed of the Vaughn Member persists
across the South arch eastward at least as far as the
Missouri River, in the Lander Crossing quadrangle.
The bed has been mapped by Dobbin and Erdmann
(1930) as “sandstone A.” A freshwater origin is proba-
ble for this bed. Fossil wood can be found on almost any
outcrop: and locally, large logs are present. In a few
places in the eastern part of the Portage quadrangle,
beds of lignitic shale are at the top of the sandstone.

The rest of the Vaughn Member consists dominantly
of clayey beds that are light to dark gray, greenish
gray, grayish green to olive green, greenish yellow,
pink, or chocolate brown and generally are very ben—
tonitic. The clayey beds are interbedded with thinner
lenticular units of gray to green bentonitic siltstone
and sandstone that are commonly tuffaceous and, in
places, are orthoquartzites. Some of the beds of clay,
siltstone, and sandstone contain small crystals of
orange-red clinoptilolite (determined by L. G. Schultz,
U.S. Geol. Survey). Locally, as in the small badland
area traversed by US. Highway 91, about 5.6—6.4 km
(3.5—4 mi) northwest of Vaughn, this zeolite is so
abundant that it imparts a pinkish color to the out-
crops. Bentonitic clay containing clinoptilolite forms
the uppermost 8.5 m of the type section. About 6 km to
the west, along Muddy Creek, black carbonaceous
shale, which has been prospected for coal, forms the top
of the member (fig. 9; also Cobban, 1955a, text fig. 2).

The Vaughn Member is easily recognized in cuttings
from wells drilled for oil and gas on the Sweetgrass
arch. The clays are largely light to medium shades of
gray or green, and the sandstones are generally light
gray to white. The rocks are very bentonitic, and most
contain small crystals of the orange-red zeolite. The
sandstones are fine to medium grained, massive, soft,
and clayey. They are composed mainly of subangular
grains of clear quartz and white, gray, black, brown,
yellow, green, and pink grains of quartz, chert, and
other minerals, including some mica. Abundant white
clay serves as a cement. Most wells reveal whitish fine-
to medium-grained sandstone 1.6—10.7 m (5—35 ft)
thick at or near the base of the member. Wells drilled
low on the west flank of the Sweetgrass arch, where the
Vaughn Member is 61—91 m (200—300 ft) thick, may
show as many as four beds of white sandstone 4.6 m (15
ft) or more thick. Black carbonaceous shale has been
penetrated at the top of the member in some wells in
the Pondera and Kevin-Sunburst oil fields.

28

 

FIGURE 9.—Upper part of Vaughn Member (light-gray bentonitic
beds bare of vegetation) capped by layer of lignitic shale (black
band) and overlain by lower part of Bootlegger Member 6.5 km
(4 mi) northwest of Vaughn in the NE‘A sec. 4, T. 21 N., R. 1 E.,
Cascade County, Mont.

The top of the Vaughn Member is readily deter-
mined in well cuttings by the abrupt change downward
from dark—gray more or less sandy shale to light-
colored clay or, more rarely, white bentonitic
sandstone or black lignitic shale. The lower contact is
not so easily placed. A unit, 6 m to more than 11 m
thick, of medium- to dark-medium-gray soft silty shale
commonly lies between the lowest whitish bentonitic
sandstone typical of the Vaughn Member and the up-
permost greenish glauconitic sandstone typical of the
Taft Hill Member. lnterbedded with this silty shale are
thin beds of light- to medium-gray very fine to fine-
grained shaly sandstone and siltstone that are slightly
glauconitic. Locally, these beds contain tiny specks of
the orange-red zeolite in addition to the glauconite.
These beds are considered to represent intertonguing
of the Vaughn and Taft Hill facies and are here as-
signed to the Taft Hill Member.

AGE ASSIGNMENT ANI) CORRELATION

The fossil record from the Vaughn Member consists
of leaves, logs, and, rarely, fragments of reptile bones.
The fossil plants, all from the vicinity of Vaughn, have
been identified by R. W. Brown (Cobban, 1951a,
p. 2180) as Pinus sp., Araucarioxylon sp., Anemia
fremonti Knowlton,Nelumbites sp., Dryandroides? sp.,
and Tempskya knowltoni Seward. Zeller and Read
(1956) regarded the genus Tempskya as a possible
guide to rocks of Albian (late Early Cretaceous) age.
Other evidence which suggests a possible late Albian
age is the position of the Vaughn Member below the
Bootlegger Member. The Bootlegger Member is an

 

BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

equivalent of part or all of the Mowry Shale of other
areas. The Mowry Shale contains Neogastroplites, In-
oceramus cf. 1. anglicus Woods, and other mollusks
that are considered as being probably of very late Al-
bian age (Reeside and Cobban, 1960, p. 28—30). A re-
cent addition to the fossil flora from the Vaughn
Member is Tempskya grandis Read and Brown.

Formerly the Vaughn Member was thought to be
equivalent to the lower part of the Mowry Shale (Cob-
ban, 1951a, p. 2180), but in light of the discovery by
Mudge (1972, p. A62) of Skull Creek fossils in the Taft
Hill equivalent, a correlation of the Vaughn Member
with the Newcastle Sandstone of the Black Hills seems
more logical.

DESCRIPTIVE SECTIONS OF THE VAUGHN MEMBER

The following type section and reference section are
based chiefly upon field descriptions. Only a small
amount of mineralogical work, mainly related to iden-
tification of the minerals clinoptilolite and chamosite,
has been done. The type section was originally meas-
ured by R. W. Lemke and E. K. Maughan in 1956, with
minor revisions by R. W. Lemke and A. F. Bateman in
1973. The reference section was measured by C. E.
Erdmann in 1968 and 1969. The lithology in both sec—
tions is similar, but the stratigraphic units have been
subdivided considerably more by Erdmann in the re-
ference section. Also, similar strata in the two sections
are not always described in exactly the same way, and
therefore correlation of beds between the two sections
is not always possible. In addition, the reference sec-
tion, unlike the type section, is subdivided into three
units (upper, middle, and lower), based upon the in-
ferred environmental conditions that existed during
deposition of the units. In spite of these inconsisten-
cies,we believe that description of both sections herein
is desirable.

Type section of Vaughn Member

[Measured by R. W. Lemke and E. K. Maughan, 5.&6.1 km (3.32.8 mi) north-northeast of
Vaughn in the NWI/ANE'A sec. 6, T. 21 N., R. 2 E,, and SWVaSE‘A sec. 31, T. 22 N., R, 2 E,,
Cascade County (Vaughn quadrangle) (fig. 10)]

M Ft
Blackleaf Formation:
Bootlegger Member (basal beds):

21. Sandstone, gray, fine-grained, moderately fri-
able; weathers mottled bluish gray and
orange brown; shaly at base, becoming more
sandy toward top; upper 18 cm is greenish
gray (5GY 6/1) that weathers pale olive (10Y
6/2), is platy, and contains Lingula sp ,,,,,,

Vaughn Member:

20. Shale, distinctly fissile, grayish-black, nonben-
tonitic, noncalcareous, carbonaceous, par-
ticularly in basal part. Forms a grassy slope,
in contrast to nonvegetated beds below ____

19. Concretions, dark-brown, noncalcareous, fer-

2.1 6.8

3.3 10.9

VAUGHN MEMBER

LITHOLOGIC
SVMBOLS

METR ES FEET

0—1

7 TTVIW

<12 5.?
-— 3
8 o.
H r.
3 3
(D (D

—— 20

Shale

——40 99
99

Calcareous
concretlons

—60

E

 

2° # Bentonite

s/Vx/v/
VVVVV

Zeolitized
tuff

 

 

El

Carbonaceous

R‘ 2 E’ shale

 

0 1MILE

 

0 1 Kl LOMETRE

 

 

 

 

FIGURE 10.—Type section of the Vaughn Member of
the Blackleaf Formation and map showing line of
measured section, sec. 6, T. 21 N., R. 2 E., and sec.
31, T. 22 N., R. 2 E. Numbers on the left side ofthe
column are key beds in the measured section. On
the map, the arrow points upward stratigraphi-
cally; B, base, and T, top of member.

Type section of Vaughn Member—Continued
Blackleaf Formation—Continued
Vaughn Member—Continued

19. Concretions, etc—Continued M Ft
ruginous; weather to a very dark metallic
brown to bluish black ____________________ .1 .2

18. Clay, bentonitic; contains red specks of clinopt-
ilolite. Divisible into several subunits that
form distinct benches (mostly with spongy
surfaces) separated by low scarps; subunits
range in color from light greenish gray
through dark gray to chocolate brown. In-
cludes 18 cm of dark-gray siltstone and 1.6 m
of alternating beds of hard tuffaceous
siltstone and light~gray bentonitic clay.
Forms nonvegetated slope ,,,,,,,,,,,,,,,, 8.4 27.8

17. Siltstone, medium-light-gray (N 6), very hard
and dense, tuffaceous, lenticular; weathers
very light gray (N 8); has very fine uneven
laminae; contains red clinoptilolite grains
and small nodules of light-green clay. Local-

 

16.

15.

14.

13.
12.

11.
10.

29

Type section of the Vaughn Member—Continued
Blackleaf Formation—Continued
Vaughn Member—Continued

17. Siltstone, etc—Continued

ly, upper 15 cm has a distinct red appear-
ance, owing to abundance of finely dissemi-
nated clinoptilolite ______________________
Clay, bentonitic, noncalcareous; contains red
grains of clinoptilolite. Divisible into several
subunits that form distinct benches (mostly
with spongy surfaces), separated by low
scarps. Subunits are light greenish gray to
dark gray (a few are greenish gray to olive
green). Includes two beds of dark'gray hard
and dense tuffaceous siltstone 30 cm or less
thick and also a few beds ofpapery shale near
top. Forms nonvegetated slopes ,,,,,,,,,,,,
Clay, bentonitic, slightly silty, moderately
greenish yellow (10Y 7/2) to grayish-green;
mottled with markings of medium-gray (N 5)
clay that may be of organic origin or fillings
in small desiccation cracks ,,,,,,,,,,,,,,,,
Sandstone, light—gray, fine-grained, dense,
noncalcareous; weathers salmon pink;
breaks along indistinct joints into rectangu-
lar blocks about 30 cm long and 15 cm wide
Siltstone, light-gray, locally clayey ,,,,,,,,,,,
Siltstone, medium-olive-gray (5Y 5/1), tuffa-
ceous(?), dense, and very hard; weathers yel-
lowish gray with some light-brown-stained
surfaces; many sharply angular quartz
grains, some light-green grains, and a few
black grains and small black plant frag-
ments. Breaks into very small, sharply angu-
lar pieces ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Clay, light-gray, silty, slightly bentonitic 1"-
Sandstone, gray, fine-grained, resistant,
slightly calcareous; breaks into irregular
blocks owing to indistinct jointing. Abundant
fossil wood at base _________________________

. Claystone concretions, dark-brown, tabular (as

much as 0.6 m in diameter), slightly fer-
ruginous, very resistant, noncalcareous;
weather to very dark metallic brown to
metallic bluish black; some plant
fragments ________________________________
Clay, greenish-gray and buff, bentonitic, non-
calcareous ______________________________
Ironstone concretions, dark-brown, tabular,
slightly calcareous; weather bluish and
brownish black with a slight metallic
luster ____________________________________
Sandstone, light-yellowish-gray, fine— to
medium-grained, hard, dense, noncalcare-
ous; weathers medium to dark brown; well—
developed parallel joints about 7.5 cm apart
cause sandstone to break into blocks 30—46
cm long. Abundant rushlike plant
remains ________________________________
Sandstone, pale—greenish-yellow (10Y 8/2),
medium-grained, very friable, thinly bedded
to massive, somewhat crossbedded, arkosic,
porous, slightly calcareous; consists chiefly of
subangular to subrounded quartz grains,
abundant feldspar, and some dark grains (in-

M Ft
5 1.5
4.9 16.2
1.0 3.2
2 .8
6 2.0
3 1.0
6 2.0
2 .5
1 .4
1.3 4.4
1 .2
1 .3

30 BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

Type section of the Vaughn Member—Continued
Blackleaf Formation—Continued
Vaughn Member—Continued

15. Sandstone, etc—Continued M Ft
cludes chert, magnetite, and biotite); light-
colored petrified wood in logs as much as 1.8
In long. Locally, 1.8—2.7 m (6—9 ft) above base
is a finer grained more resistant sandstone
that is grayish brown, massive, and highly
calcareous. Scattered ironstone concre—
tions ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, g E

Total Vaughn Member ________________ 26.3 86.4
Taft Hill Member (part of upper unit):
4. Siltstone, light- to dark-gray, shaly to sandy,
thinly bedded, noncalcareous to highly cal-
careous; weathers light yellowish gray (cut
by fracture fillings that weather yellow
orange); includes, near the top, sandstone
lenses several feet long and as much as 0.5 m
thick that are medium gray, fine
grained, calcareous, dense, and weather
orange brown. Local lenticular sandstone
near base. Upper boundary gradational __-1 3.2 10.4
3. Clay, gray to greenish—gray, shaly to silty, ben-
tonitic; weathers light gray with crackly sur-
face; scattered nodular fine-grained concre—
tions and local platy sandstone as much as
0.8 m (2.5 ft) thick in upper part. Lower 1.2 m
is more bentonitic and contains a few red
clinoptilolite grains ______________________ 5.4 17.7
2. Limestone, yellowishgray (5Y 8/1), coarsely
crystalline, layered; weathers brown; poorly
developed cone—in-cone structure; breaks in-
to small irregularly shaped brown frag-
ments ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, .1 .3
1. Siltstone, light-olive-gray (5Y 5/2) to dark-
greenish-gray (5GY 4/1), dense, hard, proba-
bly glauconitic, slightly calcareous to noncal-
careous, contains Lingula sp. and macerated
fossil plants. A clayey carbonaceous shale 15
cm thick divides the siltstone into two sub-
units. Unit cut by well-developed parallel
joints that strike N. 71° W ________________ .9 3 0

Total measured thickness of part of
Taft Hill Member (upper unit) 9.6 31.4

Reference section of Vaughn Member

[Measured by C. E. Erdmann, June 25»0ct. 3, 1968, and Dec. 17721, 1969. Base ol'section
starts in north center NEl/iNW‘ANEM} sec. 11, T. 21 N., R. 1 E.,just below surface ofU.S.
Highway 91 (Interstate 15!. Measurements extend along northeast side of highway to
summit of small conical hill in NE. cor. SW‘ASW'ASE‘A sec. 2, T. 21 N., R. 1(E.;|thence
northeast to southwest face of escarpment. Top ofmeasurement in center NE‘ASW‘ASE‘A
sec. 2. Vaughn quadrangle, Cascade County, Mont]

M Ft
Blackleaf Formation:
Bootlegger Member (basal part):
28. Sandstone, greenish-gray (5GY 6/1), fine
grained, compact, thin slabby layered, cal-
careous, hard, resistant; weathers olive
brown; contains trace fossils ______________ 0.3 1.0
27. Shale, medium-dark-gray, clayey, poorly fis-
sile. Rusty laminae at intervals of about 3 cm
in lower 1.5 m. Weathers into cracked clay
slope ____________________________________ 4.3 14.0

 

Reference section of Vaughn Member—Continued

Blackleaf Formation (basal part)—Continued
Disconformity; erosional relief slight, about 1 m in this

vicinity.
Vaughn Member:
Upper unit (lake or swamp environment):

26. Sandstone, yellowishgray, thin and platy
layered, fine— to medium-grained, locally
crossbedded. Surface of upper bed may
show irregularities resembling oscillation
ripple marks: wave length, 1.0 ft;
amplitude, 0.1; strike, S. 55° E. Contains
small carbonized logs. Usually makes a
massive unit that supports resistant
bench. Upper surface also may be marked
by inclusion of small irregular reworked
lumps of light-bluish-gray (53 7/1)
siltstone containing broken laminae and
thin pods of medium- to coarse-grained
yellowish-gray, cherty sandstone, and an-
gular fragments of brownish-gray car-
bonaceous shale ________________________ 1.8

25. Sandstone, yellowish-gray; in thin (5—10 cm)
layers separated by somewhat greater
thicknesses (15—30 cm) of soft yellowish-

gray clayey siltstone ____________________ 2.6
24. Shale, brownish-gray, silty, carbonaceous,
soft, flaky ______________________________ .2

23. Clay, olive-gray, silty, slightly carbonace-
ous. Weathered surface cracks or checks;
unvegetated ____________________________

9"
N)

Measured thickness of upper unit 111.
Middle unit (pyroclastic clays, water laid):

22. Mudstone, medium-gray; weathers light
gray; contains numerous small dark gran-
ules of chamosite. Matrix firm, moderately
resistant, weathering out of slope. Base ir-
regular ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

21. Claystone, very dark gray, nearly black; has
small undetermined light—gray specksd"

20. Claystone; weathers pinkish gray, as in
unit 18 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, .1

19. Tuff, vesicular, water laid (as in unit 17).
Pale olive gray, with vesicles occupied by
orange-pink clinoptilolite. Compact; tough .2

18. Claystone; weathers pinkish gray (5YR 8/1) 3.0

17. Tuff, vesicular, silty, light-greenish-olive—
gray; weathers very light pinkish gray. In
thin layers. Vesicles 0.2—0.6 mm in diame-
ter and filled with clay. Some layers are
hard, silicified, and float from them is
characterized by a grayish~red (10R 4/2) to
dark-reddish—brown (10R 3/4) clinoptilolite
patina, giving the pieces the appearance of

be

‘m

a reconstituted igneous rock ____________ .7
16. Claystone, greenish-olive-gray. Probably

largely montmorillonite ________________ 1.1
15. Claystone, pink; contains clinoptilolite 1", .2
14. Claystone, light—olive-gray ________________ .9

13. Claystone, light-olive-gray to pinkish; con—
tains small grains of clinoptilolite. Weath—
ers into soft spongy unvegetated surface
layer with expanded "popcorn” texture,
which flows downslope when wet. Thin
siltstone layer at top ____________________ 2.4

'2»

[.

Ft

'01

H
6310
«)0

H-

1.0

1.9

2.2

3.7

3.1

8.0

BOOTLEGGER MEMBER 3 1

Reference section of Vaughn Member—Continued

Blackleaf Formation—Continued
Vaughn Member—Continued

Middle unit, etc—Continued

12. Tuff and siltstone, medium-gray and

greenish-gray. Tuff has vesicles occupied

by light-olive-green clay ________________

11. Sandstone; in rounded, flattened, oval balls.

Hard, light gray, fine grained, clayey, with

a few galls of greenish clay. Top of bed

slightly undulating ____________________

10. Mudstone (claystone), light-yellowish-gray.

Surface cracked, tough. Makes unvege-

tated slope ____________________________ 1.

Measured thickness of middle unit A“- 11.

R
3;

._..
'cc

in

1.5

R1
U!
01

l
I-

oo
4:.
r—A
K]

H
“-

Lower unit (fluviatile):

9. Sandstone, light-gray, fine- to medium-
grained. Upper 15 cm contains small pel-
lets of light-gray clay. Thinly laminated by
slightly more resistant brownish-gray
crusts that may be a variety of parting
lamination ____________________________ .4 1.3

8. Sandstone, very light yellowish gray (5Y
9/1); predominantly fine to medium angu-
lar to subangular quartz with some chalky
feldspar, with about 6 or 8 percent dark
grains, of which biotite in flakes as much
as 0.1 mm wide are most abundant, with
chert next, in a tight cement of very light
gray (white) clay. Becomes light greenish
gray (5GY 8/1) upon weathering through
color change ofcement, and friable upon its
loss. In thin (1—24 cm) massive layers,
some of which show low-angle east-dipping
cross-lamination. Hard and tough when

fresh, forming a low resistant ledge ______ 2.5 8.3
7. Sandstone, clayey; light-gray; orange mot-
tling; soft _______________________________ 1.4 4.5

6. Sandstone, light-gray, fine- to medium-
grained; in thin alternating layers with
softer clayey sandstone. Poorly exposed __ 2.7 9.0

5. Sandstone, light— to medium-gray, fine- to
medium-grained; in massive 10- to 15-cm
layers, but strongly crossbedded where
thinner; lower 30 cm hard, brown, and fer-
rug‘inous in places. Base irregular. Con-
tains thin lentils of conglomeratic sand-
stone noticeably characterized by rounded
lumps of soft grayish-yellow (5Y 8/4) clay
ranging in size from 0.5-cm pellets to ir-
regular fragments 7—10 cm long and 2 cm
or more thick. Flattened clay galls are
abundant on bedding surfaces. In addition,
the matrix of coarse, cherty, subangular,
light-olive-gray sand with clay cement
exhibits sharp angular 1-cm pieces of firm
compact yellowish-gray to pale-olive silt-
stone; subround pebbles of dark-gray chert
3—12 mm in diameter; and clear glassy
quartz in subround grains 2 mm in diame-
ter that break with conchoidal fracture.
This facies in particular, which is uncom-
mon, makes the basal conglomerate of the
Vaughn Member ______________________ 1.2 4.0

 

Reference section of Vaughn Member—Continued
Blackleaf FormationfiContinued
Vaughn Member—Continued
Lower unit (fluviatile)—Continued M F‘
Measured thickness of lower unit ___. g 27.1
Total measured thickness of Vaughn
Member (rounded) ________________ 25.0 86.0
Disconformity; slight erosional relief.
Taft Hill Member (part of upper unit):
4. Sandstone, medium—yellow-orange, soft, fri-

able, fine-grained; weathers moderate

brown ________________________________ 5 1.7
3. Sandstone, medium-grained; light olive at

top ____________________________________ .2 7
2. Sandstone, clayey (mudstone), soft; surface

cracks. Poorly exposed __________________ 3.4 11.2

1. Clay ironstone; in fragmented Chippy
mounds that have diameters of 0.5—1 m at
intervals of 3 m or more, on thin gray-
green sandstone. Ironstone surface over-
lain by thin light—brown recrystallized cal-
cite. Base concealed by alluvium ,,,,,,,, _2

Measured thickness of part of Taft Hill
Member (upper unit)

BOOTLEGGER MEMBER
NAME AND DEFINITION

The Bootlegger Member is the “upper member of
sandy shale and sandstone of marine origin” that was
correlated with the upper part of the Mowry Shale by
Cobban (1951a, p. 2180). The member was named by us
(Cobban and others, 1959, p. 2791) from the exposures
along the east-trending escarpment that is crossed by
the Bootlegger Trail 11—13 km (7—8 mi) north of Great
Falls near the common corner of Tps. 21 and 22 N., R. 3
E., and Tps. 21 and 22 N., R. 4 E., Cascade County
(Great Falls quadrangle). Inasmuch as the member is
not completely exposed at any one locality, the section
presented here as the type is composite from measure-
ments at several places along the escarpment west-
ward for more than 24 km (15 mi) from the crossing of
the Bootlegger Trail. Although parts of the section are
not well exposed, the total thickness can be measured
in roadcuts along US. Highway 91 (Interstate 15) and
Vicinity northwest of Vaughn in secs. 34 and 35, T. 22
N., R. 1 W. Thin beds of medium-gray sandstone, gray
siltstone, dark-gray shale, and yellowish bentonite,
compose most of the Bootlegger Member. Much of the
sandstone, siltstone, and shale is interlaminated.

THICKNESS

The composite type section is 100 m (329 ft) thick.
However, the overall thickness of the member in sec. 3,
T. 21 N., R. 2 E., and sec. 34, T. 22 N., R. 2 E., is 84 m
(275 ft). This difference in thickness appears to result

32

chiefly from thinning of bed 3 and also above bed 30 of
the type section as it is traced westward. Along Muddy
Creek, in sec. 4, T. 21 N., R. 1 E., and sec. 33, T. 22 N.,
R51 E., the Bootlegger is 72.5 m (238 ft) thick. Farther
nort‘heast in sec. 4, T. 22 N., R. 6 E., and in sec. 16,
T. 23 N., R. 6 E., Lemke and Maughan measured a
total thickness of 87.2 m (286 ft). In the subsurface
Cobban (1951a, p. 2180) noted that the member “thins
westward from 320 feet on the east flank of the Sweet-
grass arch to 60 feet on the west flank. This westward
thinning is due to gradual facies change of the lower
part into non-marine sediments.”

OUTC ROP D IS’I‘RIB UTION

On the South arch the Bootlegger Member forms a
conspicuous escarpment that extends from Gordon on
Muddy Creek near the center of the Vaughn quad-
rangle eastward across the middle of the Great Falls
quadrangle to Blackhorse Lake Flat. From there the
escarpment strikes northeastward across most of the
Portage quadrangle but is obscured by overlying gla-
cial deposits. The member crops out here and there
northeastward at least as far as the Missouri River in
the Lander Crossing and Carter quadrangles. In the
Vaughn quadrangle the Bootlegger is exposed from the
vicinity of Vaughn northwestward 17 km (10.5 mi) up
Muddy Creek to the center of sec. 2, T. 22 N., R. 1 W.,
where it disappears below the valley floor. West of
Vaughn the Bootlegger crops out along the Sun River
valley as far as 2.4 km (1.5 mi) beyond the town of Sun
River. South of Vaughn the basal part of the member
caps Taft Hill in the Vaughn and Cascade quadrang-
les.

Outcrops 0f the Bootlegger Member are restricted to
the central part of the Kevin—Sunburst dome in sec. 5,
T. 33 N., R. 1 W. (Shelby quadrangle) where the upper
3.5~4.5 m crops out, and the very top also was exposed
during the excavation of the stock watering pond in the
NWl/ZiNEMi sec. 32, T. 34 N., R. 1 W. These exposures
bear very close resemblance in texture and composi—
tion to typical Bootlegger where it is crossed by US.
Highway 91 about 9.5 km north of Vaughn.

Outcrops of Bootlegger lithology are not known in
the Disturbed belt, owing to its probable replacement
by the Vaughn Member.

GENERAL DESCRIPTION

On Taft Hill south of Vaughn a 10-m-thick fine-
grained massive bed of sandstone forms a light-brown
cliff at the base of the Bootlegger Member. This
sandstone, mapped by Dobbin and Erdmann (1930) as
”sandstone B,” is equivalent to the 17 m (56 ft) of sandy
beds that form the basal part of the Bootlegger
Member in its type section. There the basal part of the

 

BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

member consists of 8.2 m (27 ft) of light-gray fine- to
medium-grained thin-bedded sandstone overlain by 4
m of shaly siltstone and in turn by a fine- to medium-
grained sandstone unit of two 0.3-m-thick beds of hard
ledge-forming sandstone separated by 1.4 m of softer
shaly sandstone. The lower of these 0.3 m ledges
weathers dark brown and contains Lingula, a
brachiopod genus found in both brackish-water and
normal marine water. Lemke and Maughan traced
these two ledges of sandstone from Muddy Creek, in
the center of the Vaughn quadrangle, eastward across
the Great Falls and Portage quadrangles and into the
Lander Crossing quadrangle where the two beds of
sandstone dip below the Missouri River at the mouth of
Black Coulee. They found that the interval separating
the two sandstone ledges varied from 1.5 to 4.5 m. In
the Portage quadrangle the lower ledge is the more
conspicuous of the two, whereas the upper ledge is gen-
erally the more prominent in the western half of the
Great Falls and Vaughn quadrangles. The sandy to
shaly interval underlying these hard sandstone ledges
and overlying the Vaughn Member thins westward
from the type section into the Vaughn quadrangle.
About 4 km northwest of Vaughn, the lower sandstone
ledge lies a metre or so above the Vaughn Member.

In the type section the upper of the two ledges of
sandstone is overlain by 6.4 m (21 ft) of dark-gray
shale that contains a layer of bentonite 25 cm (10 in.)
thick. Above this shale is 4.4 m (14.3 ft) of sandy
siltstone characterized by irregular vertical and
diagonal fractures. A thin brown-weathering bed of
hard medium-grained sandstone forms a small ledge
on top of the siltstone. Above the sandstone is 1.7 m
(5.4 ft) more of shaly siltstone. This siltstone and
sandstone sequence thins eastward and is very shaly
where it dips under the Missouri River below the
mouth of Black Coulee in the northwestern part of the
Lander Crossing quadrangle. Locally, particularly
along the escarpment north of Blackhorse Lake Flat in
the Great Falls quadrangle, and at a few other places
in the Portage and Vaughn quadrangles, the siltstone
and sandstone sequence is well indurated and forms
well—defined benches.

The silty unit in the type section of the Bootlegger
Member is overlain by 10.8 m (35.3 ft) of very dark
gray shale that contains a bed of bentonite 0.7 m (2.2
ft) thick in the basal part. Above this shale is a unit
about 12 m (40 ft) thick (beds 17—21 of type section) of
thinly bedded sandstone and siltstone with a local bed
of black-coated chert pebbles near the middle. This
sandy unit is believed to be the equivalent of the
sandstone along Highwood Creek (Reeves, 1929, p.
162, bed 24). Another shaly unit about 9.5 m (31 ft)
thick overlies these sandy beds and contains a 2-

BOOTLEGGER MEMBER 33

m-thick bed of greenish-yellow bentonite near its base
that forms a conspicuous light-colored poorly vegetated
band for many miles westward along the escarpment
from the type section. The 12-m (39-ft) thickness of
beds above this shaly unit is largely concealed but in-
cludes two thin conglomeratic beds with black-coated
chert pebbles as much as 5 cm in diameter. The next
7.6 In (25 ft) consists of poorly exposed beds of dark
shale and thick layers of bentonite including one 3 m
(10 ft) thick. The 3-m-thick bentonite contains, espe-
cially in its upper part, lenselike masses of zeolitic tuff
and forms a conspicuous white band along the escarp-
ment westward for more than 24 km. It is probably the
westward extension of the Arrow Creek Member of the
Colorado Shale of central Montana (Reeside and Cob-
ban, 1960, p. 8, pl. 1). A black chert sandstone bed as
much as 0.9 m thick just below the base of the bento-
nite bed forms the upland surface over several square
miles west and northwest of the type section. The rest
of the Bootlegger Member, about 21 m (70 ft), is mostly
interbedded and interlaminated sandstone, siltstone,
and sandy shale that contain abundant fish scales.
Several layers of bentonite are present, and one that is
about 15 cm thick lies at the top. Just beneath this
uppermost layer of bentonite is a brown medium- to
coarse-grained massive bed of hard sandstone about 30
cm (1 ft) thick crowded with fish bones and scales and,
here and there, black-coated chert pebbles as much as
5 cm in diameter. This conspicuous bed of coarse sand-
stone is present from the western part of the Great
Falls quadrangle westward across most of the Vaughn
quadrangle. It can be seen readily along US. Highway
91 about 9.6 km (6 mi) northwest of the intersection
near Vaughn with US. Highway 89 and forms the up-
land surface for some distance to the north and
northeast.

The upper and lower contacts of the Bootlegger
Member are sharp. Along Muddy Creek in the Vaughn
quadrangle, gray shaly fine-grained sandstone at the
base rests abruptly on black carbonaceous shale that
forms the top of the Vaughn Member (fig. 9; Cobban,
1955a, text fig. 2). At other localities gray shaly
sandstone or darker sandy shale forming the basal bed
of the Bootlegger rests sharply on light-gray clay or
white crossbedded sandstone at the top of the Vaughn
(fig. 8). The boundary between the Vaughn and Boot-
legger Members can be seen clearly in a cut on US.
Highway 91 about 4.8 km (3 mi) northwest of Vaughn,
south of the center of sec. 2, T. 21 N., R. 1 E. The upper
boundary is determined easily in most places by a 15—
cm-thick layer of bentonite that rests on the hard bed
of coarse-grained to pebbly sandstone which contains
abundant brown fish bones. The overlying Floweree
Member of the Marias River Shale contains no bento-

 

nite and only rarely fish scales or bones. That contact
can be seen on the north, west, and south sides of the
hill that bears the Cone triangulation station in sec.
13, T. 22 N., R. 1 W., about 4.8 km west of US. High-
way 91 in the Vaughn quadrangle.

Wells drilled for oil and gas on the Sweetgrass arch
reveal a threefold division for the Bootlegger Member
at many localities on both the South arch and Kevin-
Sunburst dome. In general the basal unit is sandy, the
medial unit is soft shale, and the upper unit is sandy,
hard, and contains fish scales.

The basal subsurface unit, about 30 m (100 ft) thick,
is chiefly gray fine-grained thin-bedded sandstone in-
terbedded with darker sandy shale. Small black car-
bonaceous flakes are common. Glauconite is sparingly
present, and pyrite occurs in a few places. One or two
thin layers of black chert granules or small pebbles are
present in some wells; one such layer commonly marks
the top of this unit.

The medial subsurface unit is dominantly dark-gray
soft shale with a few thin beds of fine-grained
sandstone and bentonite. Glauconite and pyrite are
present but sparse. Granules and small pebbles of
black chert occur locally. The thickness of this soft
shaly unit averages about 15 m.

The upper subsurface unit, 18 m to more than 30 m
thick, is characterized by thin beds of hard medium-
gray sandstone and siltstone interlaminated and in-
terbedded with darker gray silty shale. Fish scales are
abundant. Several beds of bentonite are present. Al-
most all well cuttings show a few centimetres of very
coarse sandstone or conglomerate at the top of this
unit. The sandstone consists mostly of poorly sorted
clear grains of quartz showing secondary crystal faces,
subrounded to rounded colorless frosted quartz grains,
and lesser amounts of subangular gray and black
chert. Pebbles are chiefly gray chert that has a black
patina. Brown fish bones are generally present. Locally
the sandstone is somewhat an orthoquartzite. Small
amounts of pyrite occur in the sandstone in some of the
well cuttings.

The boundaries of the Bootlegger Member can be
determined as readily in the subsurface as on the out-
crop. The coarse more or less conglomeratic sandstone
layer at the top is an excellent key bed. Where it is
absent, the top can be placed at the abrupt change from
the dark—gray shale of the Floweree Member to the
lighter gray fish-scale-bearing interlaminated and in-
terbedded sandstone, siltstone, and silty shale of the
Bootlegger. The lower contact is equally as sharp. It
marks the change from dark-gray silty or sandy shale
of the Bootlegger to light-colored clay, white bentonitic
sandstone, or black carbonaceous shale at the top of the
Vaughn Member.

34 BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

AGE ASSIGNMENT AND CORRELATION

The Bootlegger Member contains the common
Mowry fish scales described by Cockerell (1919) as
Holcolepis transversus, Leucichthyops vagans, and
Erythrinolepis mowriensis. The ammonite genus
Neogastroplites has been found in the member on Belt
Butte 29 km (18 mi) southeast of Great Falls and at
several localities on the Sweetgrass arch north, north-
west, and west of Great Falls. This ammonite seems to
range in age from latest Albian to early Cenomanian.

The Bootlegger Member is correlated with the
Mowry Shale of central Montana and the Black Hills
region. Both units contain Neogastroplites and abun-
dant fish scales. However, the Bootlegger Member is
much less siliceous than the Mowry Shale, lacks the
silvery—white weathering, and is very much sandier. It
can be interpreted as a near-shore facies of the Mowry
Shale. Exposures of the upper part of the Bootlegger
Member near Carter Ferry (Carter quadrangle)
suggest a gradation to typical Mowry Shale aspect.
Here these beds are more siliceous and in part weather
grayish white.

TYPE SECTION OF THE BOOTLEGGER MEMBER

The following type section is based almost entirely
upon field descriptions. Only a limited amount of pet-
rographic and mineralogic work was done. This was
confined mostly to the identification of zeolitic tuff in
some of the bentonite beds, which previously had been
referred to as porcellanite. Because no great thickness
of section is exposed at any one place, the type section
is a composite section extending over a distance of ap—
proximately 32 km (20 mi). Therefore, the member at
no one locality has the thickness or exactly the lithol-
ogy described in the type section.

Type section of the Bootlegger Member

[Measured by R. W. Lemke and E. K. Maugham, along escarpment that is crossed by the
Bootlegger Trail 96 km (6 mi) north of Great Falls, Cascade County, Great Falls quad—
rangle, and near Cone triangulation station, Teton County, Vaughn quadrangle: Units
1'10, SW% sec. 31, T. 22 N., R. 4 E.; units 11730, SEl/a sec. 36, T. 22 N., R. 3 E.; units
31738, SEl/a sec. 35, T. 22 N., R. 2 E; units 39452, NEl/4 sec. 33, T. 22 N., R. 2 E.; units
53—54, SE‘A sec. 29, T. 22 N., R. 2 E.; units 54—55, SEQ/4 sec. 13, T. 22 N., R. 1 W. (fig. 11)]

M Ft
Marias River Shale:
Floweree Member (part of basal unit):
56. Siltstone, dark—gray, sandy to shaly, thinly
bedded, somewhat platy; weathers to bluish
gray with yellow-brown mottling __________ 1.5 5.0
Blackleaf Formation:
Bootlegger Member:
55. Bentonite, grayish-yellow; impure with small
selenite crystals __________________________ .2 .6
54. Sandstone, yellowish—brown to brown (weath—
ered), medium- to coarse-grained, resistant,
blocky, contains abundant fish bones and
scales. Locally contains numerous black-

 

Type section of the Bootlegger M ember—Continued
Blackleaf F ormation—Continued
Bootlegger Formation—Continued
54. Sandstone, etc—Continued M Ft
coated gray chert pebbles as much as 5 cm
long. Forms upland surface over many
square kilometres to the north ____________ .3 1.0
53. Covered 11.0

52. Sandstone, light-gray, fine—grained, platy;

weathers grayish tan; upper 0.9 m is calcare-

ous. Contains fish scales __________________ 2.7 9.0
51. Covered ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 3.2 10.5
50. Bentonite, yellowish-brown ,,,,,,,,,,,,,,,, .2 .5

49. Siltstone, dark-gray, sandy, platy; alternates
with silty brownish-gray platy sandstone.

Contains fish scales ,,,,,,,,,,,,,,,,,,,,,, 2.1 7.0
48. Covered ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 1.5 5.0
47. Bentonite, yellowish-white __________________ .3 1.0
46. Siltstone, dark-gray, sandy, thin-bedded,

platy; contains fish scales ________________ 1.4 4.5
45. Covered __________________________________ 1.7 5.5
44. Siltstone, dark-gray, sandy, thin-bedded,

platy; contains fish scales ,,,,,,,,,,,,,,,, 2 .5
43. Bentonite; greenish-yellow and pure in lower

part; grades upward into light-gray silty im-

pure bentonite __________________________ 9 3.0
42. Siltstone, dark-gray, sandy, thin—bedded,

platy; contains fish scales ,,,,,,,,,,,,,,,, .6 2.0
41. Shale, gray to tan, sandy __________________ .5 1.8

40. Bentonite, greenish-yellow __________________ .1 .4
39. Siltstone, dark-gray, sandy, thin-bedded,

platy; alternates with fine-grained medium-

gray sandstone that weathers bluish gray.

Contains fish scales ______________________ .6 2.0
38. Siltstone, dark—gray, sandy; alternates with

silty shale. Thin layer of impure bentonite

about midway in unit ,,,,,,,,,,,,,,,,,,,, 1.5 5.0
37. Bentonite, greenish-yellow __________________ 1.1 3.5
36. Siltstone, dark—gray; weathers yellowish

orange on flat surfaces; shaly ,,,,,,,,,,,,,, 1.1 3.6
35. Bentonite, greenish-yellow __________________ .3 .9
34. Shale, brown, silty ,,,,,,,,,,,,,,,,,,,,,,,, .3 1.0

33. Shale, silty, moderately fissile; nearly black
except for yellow powder along bedding
planes ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 1.5 4.9

32. Bentonite; yellowish green at base grading
upward into gray silty impure bentonite at
top. About midway in interval are lenslike
masses, commonly 1—3 In long and 0.3—0.6 m
thick, of white thin and irregularly bedded
zeolitic tuff that breaks into angular t0
rounded splintery pieces. Bentonite is iron
stained and impure in upper 1.2 m iiiiiiii 3.0

31. Shale, dark—gray to black, silty, distinctly
fissile ____________________________________ .5 1.5

30. Sandstone, light-gray, fine- to coarse-grained,
resistant, blocky, noncalcareous; mostly
quartz with a few black chert grains; fairly
numerous gray-blue flat claystone nodules as
much as 10 cm long. Contains fish scales.

Locally conglomeratic with very numerous
black-coated chert pebbles 3—50 mm long.
Unit locally as much as 0.9 m thick

29. Covered. A bentonite bed indicated at base of
interval ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 6.9

10.0

22.5

29

   
    
   

32

54

53

 

Top

 

BOOTLEGGER MEMBER

 

 

 

 

 

 

 

 

 

 

 

FLZE. H.3E.

 

.36

35

LITHOLOGIC
SYMBOLS

Chert pebbles

 

m
2’! m 2;:
_ 3~
H
a g
g 0 .;.;

D '.‘.

(D 0

Shale

— m
3 m
= a
51’. o
o 3
3 _.
0 F6

concretions

D

Covered

METRES FEET
O

O

(I)!!!

|
|
8

|
8

 

f 6°
20

1 2 3 MILES

2 3 4 KILOMETRES

H.3E. R.4E.

 

"36

 

 

 

 

 

 

 

 

 

 

FIGURE 11.—Type section ofthe Bootlegger Member of the Blackleaf Formation and map showing line of measured
section, sec. 31, T. 22 N., R. 4 E., sec. 36, T. 22 N., R. 3 E., secs. 29, 33, and 35, T. 22 N., R. 2 E., and sec. 13, T. 22
N., R. 1 W. Numbers on the left side ofthe column are key beds in the measured section. On the map, the arrow
points upward stratigraphically; B, base, and T, top of member.

36

28.

27.
26.

25.

24.

23.

22.
21.

20.

19.

18.

17.

16.
15.

14.

13.

12.
11.

10.

BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

Type section of the Bootlegger Member—Continued
Blackleaf Formation—Continued
Bootlegger Member—Continued

Sandstone, gray, blocky, resistant, calcareous;
weathers dark gray. Conglomeratic with
very numerous black-coated gray chert peb-
bles mostly about 3 mm long. Contains fish
scales ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Covered __________________________________

Bentonite; greenish yellow at base grading
upward into bentonitic black clay ,,,,,,,,,,

Siltstone, gray, shaly, sandy, noncalcareous;
weathers to irregular ledge ______________

Shale, nearly black, distinctly fissile. Bentonit-
ic near top ______________________________

Bentonite; dark yellowish green in lower part
grading upward into grayish-green silty im—
pure bentonite at top. Contains tuffaceous
lenses similar to unit 32 __________________

Clay, dark-gray, bentonitic ________________

Siltstone, thinly bedded; alternates with fine—
grained sandstone and grades upward into
dark—gray fissile shale; weathers to irregular
ledge ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Sandstone, light-gray, blocky, resistant, thin—
bedded, noncalcareous ____________________

Poorly exposed. Float indicates sandstone and
siltstone beds ____________________________

Sandstone, light-gray, lenticular, resistant,
thin-bedded, noncalcareous; weathers yel—
lowish tan. Upper part breaks into rectangu-
lar blocks on surface. Locally contains abun-
dant black-coated chert pebbles ____________

Siltstone, dark—gray, sandy, thin-bedded; alv
ternates with medium—gray sandstone.
Forms irregular ledge ,,,,,,,,,,,,,,,,,,,,

Shale, silty, noncalcareous __________________

Sandstone, silty, irregularly bedded, noncal-
careous. Contains scattered flat dark—brown
calcareous ironstone concretions about 30 cm
in diameter ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Shale, very dark gray, distinctly fissile, non-
calcareous. Ferruginous sandstone layer
about 24 cm above base. Poorly exposed,,-,

Bentonite; yellowish green in lower half grad-
ing upward into olive-green bentonitic shaly
clay. Scattered brown ovoid-shaped ironstone
concretions at top as much as 50 cm in
diameter ________________________________

Shale, dark-gray, silty, noncalcareous ,,,,,,

Siltstone, light- to medium-gray, shaly, friable,
noncalcareous; orange»brown stained films

Sandstone, medium-gray, medium-grained, rev
sistant; weathers medium brown ,,,,,,,,,,

. Siltstone, bluish-gray, sandy, friable, irregu-

larly (vertical) fractured, noncalcareous;
stained orange—yellow in places. Lenses of
fine-grained sandstone throughout interval;
a 15—cm-thick thin-bedded sandstone layer at
base. Upper halfis covered east of Bootlegger
Trail but is well exposed west of road where
it is a thin-bedded friable noncalcareous
light-gray sandstone containing thin films of
carbonaceous material that weathers mot-
tled gray and orange brown ,,,,,,,,,,,,,,

M Ft
4 1.3
4.4 14.5
3 .9
2.4 7.7
4.6 15.0
2 0 6.5
3 1.0
1.6 5.3
2 .8
2.4 8.0
3 1.0
3.4 11.0
2.4 7.9
1.8 5.8
7.5 24.7
.7 2.2
2.6 8.4
1.7 5.4
.2 7
4.4 14.3

 

Type section of the Bootlegger Member—Continued
Blackleaf Formation—Continued
Bootlegger Member—Continued M Ft
8. Shale, dark-gray, distinctly fissile, noncalcare-
ous; yellow and orange-yellow films along
parting planes. Bentonite bed, 25 cm thick,
1.2 m above base ________________________ 6.3 20.8
7. Sandstone, light-gray; fine- to medium-
grained, resistant, noncalcareous; weathers
light gray with orange-brown stains along
vertical fractures; contains small wormlike
trails __________________________________ .3 1.0
6. Sandstone, silty to shaly, irregularly fractured,
noncalcareous; grades upward into silty
shale ____________________________________ 1.4 4.5
5. Sandstone, dark—gray, medium-grained, resis-
tant, lenticular, calcareous, fossiliferous
(Lingula sp.). Upper half weathers very dark
brown and forms fairly continuous outcrops.
Lower part is finely bedded, locally crossbed-
ded, and weathers grayish tan ____________ .3 1.0
4. Siltstone, shaly, noncalcareous; grades later-
ally into sandstone beds alternating with
shaly siltstone; irregularly fractured and fri-
able and forms gentle slopes; weathered sur-
face is mottled bluish gray and orange brown 4.1 13.5
3. Sandstone, lightvgray, fine- to medium-
grained, thinly bedded (mostly less than 10
cm thick), noncalcareous; some thin films of
dark-gray carbonaceous material; weathers
mottled bluish gray and orange brown.
Well-developed vertical joint pattern strik-
ing N. 70° W. Upper 30 cm is more resistant
than remainder and forms a conspicuous
ledge with well-developed ripple marks.
Lower part includes Some thin beds of sandy
to silty shale and is rarely exposed 11111111 _8_2_ 27.0

Total Bootlegger Member (rounded) ____100.0 329.0
Vaughn Member (uppermost):
2. Shale, bentonitic, distinctly fissile, noncalcare-
ous; medium gray at base to dark gray at top 2.9 9.4
1. Shale, nearly black, bentonitic; contains red
clinoptilolite grains; distinctly fissile at top
and noncalcareous ________________________ fi __13_.2

Total Vaughn Member (measured) 111111 6.9 22.6

MARIAS RIVER SHALE

The name Marias River Shale was given by us (Cob-
ban and others, 1959, p. 2793) to the 275—365 In (900—
1,200 ft) of dark-gray Upper Cretaceous shale that lies
between the Blackleaf and Telegraph Creek Forma-
tions on the Sweetgrass arch and westward into the
Rocky Mountains front. The name is from the excellent
exposures along the Marias River, which crosses the
Sweetgrass arch between the South arch and the
Kevin-Sunburst dome. Here most of the formation is
exposed in a synclinal area, known as the Marias River
saddle (Dobbin and Erdmann, 1955), along the bound-
ary between Toole and Pondera Counties. The Marias
River Shale includes all but the uppermost sandy

FLOWEREE MEMBER

transitional beds of Stebinger’s (1918, p. 161) “shale
above the Blackleaf sandy member” in the Birch
Creek—Sun River area where he noted that “The re-
mainder of the Colorado shale above the Blackleaf
member forms the principal body of shale in this area
and by its thickness alone is readily differentiated
from the other shale units present.” The Marias River
Shale also more or less includes Willis’ (1902, p. 315,
326, 327) Benton Shale in the Glacier National Park
area and the upper or “lead-colored clay shale” part of
Weed’s (1899) Colorado Formation.

We (Cobban and others, 1959, p. 2793) divided the
Marias River Shale into four members, which are from
oldest to youngest, Floweree, Cone, Ferdig, and Kevin.
The type sections of the Floweree and Cone Members
are on the South arch, whereas those of the Ferdig and
Kevin Members are on the Kevin-Sunburst dome. In
terms of the standard stages of the Upper Cretaceous
the Floweree Member is late Cenomanian, the Cone is
late Cenomanian and early Turonian, the Ferdig is
middle and late Turonian, and the Kevin is Coniacian
and early Santonian.

The Marias River Shale occupies the surface over
much of the Sweetgrass arch. It crops out also around
the Sweetgrass Hills and in the Disturbed belt. In gen-
eral the formation thickens from east to west. East of
the Kevin-Sunburst dome the thickness is about 283 In
(930 ft) in the West Utopia oil and gas field and as little
as 277 In (910 ft) in wells drilled 16—19 km (10—12 mi)
east of this field. Northward from the West Utopia
field, the formation thickens to 293 In (960 ft) in the
Sweetgrass Hills. The full thickness of the Marias
River Shale is not known along much of the crest of the
Sweetgrass arch inasmuch as the upper part of the
formation has been eroded. Wells drilled in and about
the Cut Bank oil and gas field, west of the Kevin-
Sunburst dome, show a rather uniform northwest
thickening from 311 In (1,020 ft) in the southern part of
the Cut Bank field to 363 m (1,190 ft) on the Chalk
Butte nose 16 km (10 mi) northwest of this field. A
westward thickening is shown by wells drilled on the
northwest flank of the South arch where the formation
is 311—332 In (1,020—1,090 ft) thick.

FLOWEREE MEMBER
NAME AND DEFINITION

The Floweree Member was named for exposures
about 3.2 km (2 mi) northeast of Floweree along Black
Coulee in secs. 16 and 17, T. 23 N., R. 6 E., Chouteau
County (Carter quadrangle). It is chiefly dark-gray
shale and medium-gray shaly siltstone. The member
was correlated earlier by Cobban (1951a, p. 2174) with
the Belle Fourche Shale of the Black Hills and that

 

37

part of the Colorado Shale of central Montana that lies
between the Mowry Shale Member and the Mosby
Sandstone Member.

’I'HICKNESS

The Floweree Member varies greatly in thickness. A
total thickness of 19.4 m (63.5 ft) was measured by
Lemke and Maughan at the type section. In the
Vaughn quadrangle to the west and in the northern
part of the Cascade quadrangle, most measured sec—
tions reveal thicknesses of 6—14 m (20—45 ft). At the
Cone triangulation station (type section for the Cone
Member) in sec. 13, T. 22 N., R. 1 W., the member is
10.7 m (35 ft) thick. In sec. 6, T. 21 N., R. 1 E., 9.7 km
(6 mi) northwest of Vaughn, Maughan (1961) noted the
member to be only 3 In (10 ft) thick.

In the subsurface, the greatest thicknesses known
are in the Bears Den district of the Sweetgrass Hills
where as much as 45.7 In (150 ft) has been recorded
(Cobban, 1951a, p. 2183). Thicknesses revealed by
wells on the Kevin-Sunburst dome are commonly
23—30 In (75—100 ft). On the South arch thicknesses
greater than 15 In (50 ft) are rare. In the Pendroy area
west of the Pondera oil field, the member thins to as
little as 4 In.

The member crops out at many places along the
Rocky Mountains front. The thickness is 11.6 In (38 ft)
at the southeast edge of Glacier National Park (Cob-
ban, 1956, p. 1003) and is about 9 m in the Sun River
Canyon area (Mudge, 1972, p. A66) 97 km (60 mi) west
of Great Falls.

()UTCROP DISTRIBUTION

The Floweree Member is exposed on the southern
part of the South arch, on the crest of the Kevin-
Sunburst dome, in the Sweetgrass Hills, and along the
Rocky Mountains front.

The largest outcrop area is on the South arch. From
the Missouri River below Carter Ferry in the south-
eastern corner of the Carter quadrangle, the belt of
outcrop (largely concealed by glacial deposits) extends
west and slightly southwest to the Benton Lake area in
the northeast part of the Great Falls quadrangle. From
there it trends west across the Great Falls and Vaughn
quadrangles to Muddy Creek where the top of the
Floweree Member dips below the stream level 3.2 km
southeast of Power near the center of sec. 2, T. 22 N., R.
1 W. Southeastward from that point the outcrop fol-
lows along the west side of the valley of Muddy Creek
and crosses the divide separating the Muddy Creek
drainage from the Sun River drainage in sec. 8, T. 21
N., R. 1 E. From there the outcrop extends up Sun
River valley almost to Fort Shaw. South of the Sun
River valley the member forms a narrow south-

38

trending outcrop in the eastern part of the northwest
quarter of the Cascade quadrangle.

On the Kevin-Sunburst dome the Floweree Member
crops out around the apex of the dome, making a “ring”
possibly as much as 2.4 km in width, that in large part
is obscured by glacial deposits. The principal area of
exposure is in sees. 28, 29, 30, and 31, T. 34 N., R. 1 W.,
in the Shelby quadrangle where measurements have
revealed the lower 9 m. The total thickness in this area
probably is of the order of 24.4 m (80 ft).

West of the Sweetgrass arch the Floweree Member is
exposed near the Missouri River 3.2 km northeast of
Wolf Creek in sec. 31, T. 15 N., R. 3 W., and from the
Sun River in the SW. cor. T. 22 N., R. 8 W., north to T.
26 N., R. 8 W., and from there northwest to the south-
east boundary of Glacier National Park.

GENERAL DESCRIPTION

Dark-bluish-gray shale, lighter colored sandy shale,
and thin beds of sandstone and siltstone (fig. 12)
characterize the member. Both contacts are sharp; the
lower is marked by an abrupt change from the dark-

 

 

 

BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

gray shale of the Floweree to either a bentonite bed or
coarse fish-bone-bearing sandstone at the top of the
Bootlegger Member, and the upper boundary is
marked by an equally abrupt change from noncalcare-
ous shale to the limy shale of the Cone Member.

In the type section, 8.2 km northeast of Floweree on
the east flank of the South arch, the basal part of the
Floweree Member consists of 1.5 m of dark-gray shale
that grades upward into 4.3 m (14 ft) of gray shaly
siltstone. Part of the siltstone is characterized by odd
ellipsoidal partings that give a nodularlike appearance
to the beds. These ovoid-shaped masses weather bluish
gray with orange-yellow rinds. A crude shaly structure
is present although the overall appearance is massive.
Numerous inclined fractures filled with yellowish-
brown siltstone cross the beds. A 2.1-m-thick bed of
dark-bluish-gray shale overlies the siltstone unit. It
contains large sandy calcareous concretions that
weather light yellowish brown. A fine- to medium-
grained layer of sandstone, less than 0.3 m thick, rests
on the shale. Above the thin bed of sandstone is 4 m of
shaly siltstone cut by diagonal fractures. Distantly

FIGURE 12.—Floweree Member of the Marias River Shale at its type section in Black Coulee in the SE%SW%NE% sec. 17, T. 23 N., R. 6
E., Chouteau County, Mont.

FLOWEREE MEMBER

spaced gray sandy calcareous septarian concretions are
present near the top of this siltstone unit. Another thin
layer of yellowish-brown-weathering sandstone over-
lies the shaly siltstone. Above it is nearly 1.2 m of
siltstone that contains numerous gray septarian lime-
stone concretions. Dark-gray shale forms the upper
approximate 6 m. i

The calcareous concretions noted in the type section
are absent on the west flank of the South arch but are
well exposed in secs. 28 and 29, T. 34 N., R. 1 W., on the
Kevin-Sunburst dome, where at least nine beds of con-
cretionary limestone are present.

Local layers of chert granules and small pebbles are
present on the crest and west flank of the South arch as
well as on the east flank at the type section of the
member. Well cuttings show the presence of chert
granules and pebbles locally at other places on the
Sweetgrass arch. None of these beds are conspicuous,
and all seem to be an inch or less in thickness.

AGE ASSIGNMENT AND CORRELATION

The sandstone and siltstone layers in the Floweree
Member contain numerous worm(?) burrows or cast-
ings and a few well-preserved worm(?) tracks. About
3.2 km southwest of Power in the NW%NW%SW% sec.
2, T. 22 N., R. 1 W., thin hard sandy layers in the upper
half of the member contain the following marine fossils
(USGS Mesozoic loc. D535):

Inoceramus aff. I . mesabiensis Bergquist

Metoicoceras muelleri Cobban

Metoicoceras mosbyense Cobban
These fossils occur in the Mosby Sandstone Member of
central Montana. The Mosby, which contains the am-
monite Dunveganoceras albertense (Warren) of late
Cenomanian age, is correlated by its fossil content
with the middle part of the Greenhorn Formation of
the Black Hills.

At the type section of the Floweree Member, a still
older ammonite has been found in the bed of calcareous
septarian concretions 7.6 m (25 ft) below the top of the
member. This ammonite, Calycoceras? canitaurinum
(Haas), originally described as Mantelliceras
canitaurinum (Haas, 1949, p. 9—14, pls. 1—4, text figs.
1—4) from the lower part of the Cody Shale of Wyoming,
occurs in the basal limestone bed of the Greenhorn
Formation in the Black Hills area (Cobban, 1951a,
p. 2184).

Fossils other than worm(?) burrows or castings have
not been found in the lower half of the Floweree
Member. Possibly this half is equivalent to some part
of the Belle Fourche Shale of the Black Hills. However,
inasmuch as the Belle Fourche Shale attains thick-
nesses of more than 150 m (500 ft) and contains several
Cenomanian ammonite zones, the probability that this

 

39

thin undated part of the Floweree Member represents
much of Belle Fourche time seems unlikely.

TYPE SECTION OF THE FLOWEREE MEMBER

The following type section is based entirely upon
field descriptions. Measurements were made along a
1.2-km (0.8-mi) segment of Black Coulee along the val-
ley wall. Distinguishable beds, mostly concretionary
beds, were traced laterally. Where not exposed, the
beds were projected upstream taking into account the
local dip. The thickness of the section is believed to be
accurate to within half a metre.

Type section of the F loweree Member
[Section measured by R. W. Lemke and E. K. Maugham on the north side of Black Coulee
about 3.2 km (2 mi) northeast ofFloweree, Chouteau County (Carter quadrangle). Base of
section starts above creek bed of Black Coulee along a north-south sectiondine fence in
SE‘ASE‘ANE‘A sec. 17, T. 23 N., R. 6 E. Top ofsection is in NWIASE‘ANW‘A sec. 17, T. 23
N., R. 6 E. (fig. 13)]

M Ft
Marias River Shale:

Cone Member (basal bed; most of member exposed
upslope):

12. Limestone, concretionary, argillaceous;

weathers light grayish lavender; commonly

15—30 cm thick, 0.5—1 m in diameter, and

spaced 1 to several metres apart; septarian

with veins of yellow calcite; enclosed by fis-

sile medium-brownish-gray calcareous shale 0.3

Floweree Member:

11. Shale, very dark gray, distinctly fissile, non—

1.0

   

METRES
o _

 

-Dl'|56
—D1155

Calcareous
concretions

 

20—

 

 

2 MILES

 

 

 

0 1 2 3 KILOMETRES

 

FIGURE 13.—Type section of the Floweree Member of the Marias
River Shale and map showing line of measured section, sec. 17, T.
23 N., R. 6 E. Numbers on the left side of the column are key beds
in the measured section; numbers on the right side are USGS
Mesozoic collections. On the map, the arrow points upward
stratigraphically; B, base, and T, top of member.

40

BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

Marias River Shale—Continued
Floweree Member—Continued

11. Shale, etc—Continued

calcareous; some yellow powder along bed-
ding planes. A few beds of sandy siltstone
less than 2 cm thick. A few lenses consisting
of chert granules and small pebbles. Poorly
exposed and forms gentle slope. Inoceramus

sp ______________________________________

10. Siltstone, medium-bluish-gray, shaly to sandy;

contains scattered light-gray argillaceous
limestone concretions 15 cm thick and 30—60
cm in diameter which are septarian with
veins of yellow to brown calcite. Near base
some orange-brown ironstone that weathers
to orange-brown chips. Rarely a fossil ______
USGS Mesozoic loc. D1156:

Inoceramus sp.

Anomia? sp.

Pecten (Syncyclonema) sp.

Callista? sp.

9. Sandstone, gray, noncalcareous, thin-bedded,

resistant, locally platy; weathers to
yellowish—buff or orange-brown ledge; con-
tains some worm(?) tracks. Top surface ripple
marked __________________________________

8. Siltstone.Upper one-third is sandy and weath-

ers light bluish gray with orange-yellow
films along fracture surfaces. Lower two—
thirds, which is shalier and less resistant
than upper part, contains yellow powder
along bedding planes and is cut by diagonal
fractures with veinlike fillings. A fine-
grained sandstone about 6 cm thick divides
the two parts. Near top are a few gray cal-
careous septarian concretions that yield-
ed a single specimen of Calycoceras?
canitaurinum (Haas). USGS Mesozoic loc.
D1155. __________________________________

. Sandstone, fine- to medium-grained, somewhat

platy, lenticular; weathers grayish buff;
forms small ledge ,,,,,,,,,,,,,,,,, . _______

. Shale, dark—bluish-gray, moderately fissile;

upper part softer and more papery than lower
part and interbedded with thin layers of
siltstone. Unit cut by diagonal fractures that
have been filled with yellow and brown cal—
cite. Calcareous sandstone concretions as
much as 1.5 m in diameter occur 0.6 In below
top and weather buff yellow to buff brown,,

. Siltstone, shaly; cut by diagonal fractures that

have been filled with brown sandy siltstone

. Siltstone, somewhat shaly; consists of ovoid

masses 5—10 cm long that are grayish blue
with rinds of orange yellow. Cut by diagonal
fractures filled with yellowish-brown sandy
siltstone. Top 2 cm is brown sandstone that
contains very small black chert pebbles ",1

. Siltstone, light-gray, sandy, thin-bedded; in-

terbedded with dark—gray silty shale ,,,,,,,

. Shale, dark-gray, noncalcareous; upper part

papery, with yellow powder along bedding
planes and interbedded with shaly siltstone.

Type section of the F loweree Member—Continued

5.7

1.2

4.0

2.1

1.5

1.4

1.5

Ft

18.8

3.8

13.0

7.0

4.8

4.5

4.8

 

Type section of the F loweree Member—Continued
Marias River Shale—Continued
Floweree Member—Continued

2. Shale, etc—Continued M Ft
Grades into overlying unit ________________ g E
Total Floweree Member (rounded) ______ 20.0 64.0
Blackleaf Formation:
Bootlegger Member (top):
1. Bentonite; weathers yellowish orange; impure
near top ________________________________ 6 1.9

CONE MEMBER
NAME AND DEFINITION

The Cone Member is the so-called Greenhorn Lime-
stone of the Sweetgrass arch. It is the calcareous shale
and chalk marl member of Cobban (1951a, p. 2186), the
resistant shale member of Dobbin and Erdmann
(1930), the black lime of drillers (Erdmann and
Schwabrow, 1941, p. 283), and equivalent probably to
part of the rocks mapped around the Highwood Moun-
tains east of Great Falls by Reeves (1929, p. 162, pl. 44)
as the Mosby Sandstone Member of the Colorado
Shale. The unit was given the formal name Cone Cal-
careous Member of the Marias River Shale by us (Cob-
ban and others, 1959, p. 2794) for the excellent expo—
sures on the slopes of the conspicuous hill on which the
Cone triangulation station is situated, 6 km (3.7 mi)
south of Power near the center of sec. 13, T. 22 N., R. 1
W., Teton County (Vaughn quadrangle). The term cal-
careous is dropped from the formal name. The type
section was measured on the south slope of the hill.
Very calcareous dark—gray shale largely composes the
member.

THICKNESS

A rather uniform thickness of about 15—18 m (50—60
ft) is maintained by the Cone Member over much of the
Sweetgrass arch. The thickness is 16.5 m (54 ft) at the
type section. Stebinger (1918, p. 162) gave 15.2 m (50
ft) as an average for this member west of the Sweet-
grass arch in the Birch Creek—Sun River area. Along
the southeast boundary of Glacier National Park, the
thickness appears to be of this order although a com—
plete section has not been measured by us. In the sub-
surface the member thickens eastward from about
15—18 m (50—60 ft) on the Kevin-Sunburst dome to as
much as 24 m (80 ft) in wells drilled near the Sweet-
grass Hills. Westward from the Sweetgrass arch, the
Cone thickens to about 30 m in the Sun River Canyon
area (Mudge, 1972, p. A66).

OUI‘CRO l’ D lS'l‘RlB L’TION

The Cone Member is well exposed at many localities
on the South arch. From the type section on Cone hill
this member is exposed northwest up Muddy Creek 5.6

CONE MEMBER

km (3.5 mi) nearly to the center of sec. 34, T. 23 N., R. 1
W.; there it dips below the stream level. Eastward from
Muddy Creek the member forms a belt 3—6 km wide
across the north-central part of the Vaughn and Great
Falls quadrangles and the northern part of the Portage
quadrangle to Floweree. From the type section on Cone
hill the member crops out southward along the west
side of Muddy Creek valley to the Muddy Creek—Sun
River divide in sec. 7, T. 21 N., R. 1 E. West from there
the outcrop follows the Sun River valley about to Fort
Shaw, where the Cone dips below the stream level.
South of the Sun River valley the member is poorly
exposed. The line of outcrop seems to trend south more
or less along the eastern edge of the west third of the
Cascade quadrangle. The outcrops continue southward
from this quadrangle and follow Willow Creek in T. 17
N., R. 1 E.

On the Kevin-Sunburst dome the member is poorly
exposed at several places near the crest of the struc-
ture. Some of the best exposures are on Raglan Butte
in N1/2 sec. 13, T. 34 N., R. 2 W., 6 km (4 mi) southwest
of Ferdig. Here the beds are much disturbed owing to
glacial action. Perry (1928, p. 5) considered these rocks
as an equivalent of the Mowry Shale. The same beds
crop out just south of the NE. cor. sec. 13, T. 34 N.,
R. 3 W.

The member crops out at many localities in the Dis—
turbed belt. Powers and Shimer (1914, p. 557) recorded
it as “dark arenaceous shale” and noted the abundance
ofInoceramus labiatus [Mytiloides]. Stebinger (1918, p.
158, 161—164) described the member as “bituminous
shale and maltha limestone” and observed its occur-
rence at several places in the Birch Creek—Sun River
area. Cobban (1956, p. 1002—1004) has drawn attention
to many outcrops along the southeast boundary of
Glacier National Park.

GENERAL DESCRIPTION

The limy character of the Cone Member readily dis-
tinguishes it from the other members of the Marias
River Shale. Calcareous shale is the chief constituent.
Other constituents include argillaceous limestone,
crystalline limestone, limestone concretions, bento-
nite, and noncalcareous shale.

The boundaries of the member are extraordinarily
sharp. Both are marked by an abrupt change from the
limy shale of the Cone to the noncalcareous shale of the
underlying Floweree Member and of the overlying
Ferdig Member.

A thin layer, commonly less than 2 or 3 cm, of soft
rusty limonitic silt or siltstone marks the base in many
places. It consists of a mixture of silt, limonite, and
crystals of selenite, with here and there gray shale
pebbles, fish teeth and bones, and soft white silty

 

41

nodules. This contact layer is well exposed in the vicin-
ity of the hill capped by the Cone triangulation station
in sec. 13, T. 22 N., R. 1 W., and along the county road
about 4.3 km (3 mi) south-southwest of Power in the
NWlfliNWlfliSWlfli sec. 11, T. 22 N., R. 1 W. (Vaughn
quadrangle).

Overlying the thin limonitic basal layer is a bed of
limy shale less than 60 cm thick that contains closely
spaced limestone concretions. Most of the concretions
are 30—40 cm thick and a metre or more in diameter.
They are dark gray on fresh fracture but weather to a
pale lavender gray. The fresh and weathered surfaces
show numerous minute white specks. Most concretions
are septarian, with calcite veins that show as many as
three orders of crystallization. The outer wall of the
veins consists of a thin layer of small brown calcite
crystals. The inner and greater part of most veins con-
sists of larger crystals of translucent white or
yellowish-white calcite. Some of the thicker veins have
larger crystals of barite deposited on top of the light-
colored calcite crystals. The barite is mostly translu—
cent and pale bluish gray to pale lavender gray, but a
few clear colorless crystals are present. These septa-
rian concretions are remarkably widespread and ap-
parently extend all the way from Glacier National
Park (Cobban, 1956, p. 1003) southeastward at least as
far as Mosby 270 km (167 mi) southeast of Great Falls
(Cobban, 1951a, p. 2186).

The calcareous shale, which composes most of the
Cone Member, is very dark gray where fresh and con-
tains abundant minute white specks. Goodman (1951)
believed these specks were coccoliths and rhabdo-
spheres.

Crystalline limestone beds are present only in the
upper part of the member. These limestones are thin,
shaly, silty, and irregularly bedded. They are medium
gray where fresh and brownish gray where weathered.
Part of the limestones is composed of pelagic
Foraminifera and tiny calcareous prisms from macer-
ated M ytiloides shells. Small oysters and fragments of
Mytiloides are abundant. The limestones are hard and
crop out as a series of small ledges in contrast to the
slope formed by the shales of the lower part of the
member (fig. 14). These ledge-forming beds around the
Highwood Mountains were mistaken for the calcareous
Mosby Sandstone Member by Reeves (1929, p. 162, pl.
44).

Limestones in the middle of the member are argil-
laceous and shaly and softer than those higher in the
member. They are very dark gray but weather light
blue and then orange brown. Minute white specks,
pelagic Foraminifera, and Mytiloides mytiloides (Man-
tell) are numerous.

Seven bentonite beds are present in the type section.

42

BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

 

FIGURE 14.—Upper part of Cone Member ofMarias River Shale at its type section in the SEM; sec. 13, T. 22 N., R. 1 W., Teton County,
Mont.

The lowest and thickest is a 0.9-m white low-swelling
bed 4.3 m (14 ft) above the base. This bed is very widely
distributed and extends from Glacier National Park
southeastward at least as far as Mosby, a distance of
434 km (270 mi) (Cobban, 1956, p. 1002). Over this
great distance the bed seems to maintain a thickness of
between 0.9 and 1.5 In.

The Cone Member is readily determined in well cut-
tings by the change downward from dark-gray fissile
noncalcareous shale to massive black-gray or very
dark gray calcareous shale containing minute white
specks, and the fragments of gray limestone with
numerous inoceramid prisms. The 0.9-m-thick bed of
bentonite in the lower part of the member is easily
recognized in cuttings. On electric logs the top of the
Cone Member is represented by the well-known
“Greenhorn kick.”

The bluish-weathering argillaceous limestone and
shale (unit 5) immediately overlying the 0.9-m-thick
bed of bentonite contains numerous Mytiloides
mytiloides (Mantell) of early Turonian age. In the cen—
tral Great Plains, M. mytiloides is abundant in the
Bridge Creek Limestone Member of the Greenhorn
Limestone.

The soft calcareous shale (unit 11) higher in the type
section of the Cone Member contains the ammonite

 

Watinoceras reesidei Warren which is known also from
the Disturbed belt (Cobban, 1956, p. 1003, 1004).
Bed 14, 7~11 feet below the top of the member, con-
tains Mytiloides labiatus. The overlying 2.1 m of the
member contains fragments of Mytiloides which ap-
pear to be M. labiatus. On the Kevin—Sunburst dome
the ammonite Collignoniceras woollgari (Mantell) has
been found 1.8 m below the top of a dark-gray slightly
calcareous white-speckled shale (Cobban and others,
1956). This unit does not occur in the type section of
the Cone Member and may represent strata that
‘elsewhere are in the hiatus at the top of this member.
‘Collignoniceras woollgari is a middle Turonian am-
monite that is a guide to rocks that are equivalent in
age to the Fairport Chalky Shale Member of the Car-
lile Shale of the central Great Plains.

AGE ASSIGNMENT AND (IORRELA'I‘ION

The Cone Member contains numerous marine fos-
sils. At the type section limestone concretions at the
base of the member (bed 2) and at the top of the shale
(bed 3) that immediately underlies the 0.9 m bentonite
bed contain Sciponoceras gracile (Shumard). This
ammonite is a guide to the latest zone of the Cenoma-
nian Stage of the Late Cretaceous. In the central Great
Plains, S. gracile is confined to the basal beds of the

CONE MEMBER

Bridge Creek Limestone Member of the Greenhorn
Limestone.

In the bentonite are tuffaceous siltstone concretions,
not found at the type section, that commonly are fos-
siliferous. A collection (USGS Mesozoic loc. 25029)
from these concretions in the NW%SW%SW% sec. 28,
T. 21 N., R. 1 W., has been identified by J. B. Reeside,
Jr., as follows:

Inoceramus sp.
Phelopteria gastrodes (Meek)
Nymphalucina aff.N. subundata (Hall and Meek)
Drepanochilus ruida (White)
Sciponoceras gracile (Schumard)
Watinoceras aff. W. coloradoense (Henderson)
Type section of the Cone Member
[Measured by W. A. Cobban on the south side of the hill on which is the Cone triangulation

station 6.3 km (3.9 mi) south ofPower in the SEM; sec. 13, T. 22 N., R. 1 W., Teton County
(Vaughn quadrangle) (fig. 15)]

M Ft
Marias River Shale:
Ferdig Member (lower part):

23. Bentonite; lower part rusty brown; upper part
gray; impure, nonswelling ________________

22. Shale, black-gray, fissile, noncalcareous; tends
to resist weathering; contains a few thin lay—

ers of yellowish- and bluish-weathering hard
siltstone or very fine grained sandstone with
worm(?) tracks on the bedding surfaces.

Basal 2—3 cm limonitic and silty __________

0.5 1.5

8._1 26.6

Total part of Ferdig Member measured -1 8.6 28.1
Disconformity
Cone Member:

21. Limestone, dark-gray, shaly; weathers bluish
gray and tan; contains minute white
specks __________________________________

20. Bentonite, gray, somewhat limonitic, impure .2 .7

19. Limestone, dark-gray, shaly; weathers bluish
gray and tan; forms small ledge; contains
fish bones and scales, some fragments of
Mytiloides, and abundant pelagic Forami—
nifera

18. Shale, dark—gray, calcareous. Few very thin
bluish-weathering limestone layers. A 2-
cm-thick layer of bentonite 18 cm above
base

17. Bentonite, limonitic, shaly, impure __________ .

16. Shale, limy, hard; weathers bluish __________ .1 .4

15. Shale, calcareous; contains many very thin
limestone layers that weather brownish gray
and contain pelagic Foraminifera, worm(?)
burrows or castings, and fragments of Myti-
loides and Ostrea sp _______________________

14. Limestone; dark medium gray on fresh frac—
ture, buff gray on weathering; in thin layers
as much as 2 cm thick separated by gray limy
shale; 'forms ledges. Contains abundant
pelagic Foraminifera, small oysters, and
fragments ofMytiloides labiatus (Schlotheim),
USGS Mesozoic loc. D559 ________________

13. Shale, gray, limy, soft. Some thin layers as
much as 1 cm thick of medium-gray argil-
laceous limestone that contain fragments of

,_.
to

1.1 3.7

1.2 4.0

 

FEET
O

METRES
0 _~

llllll

—740

I»
l

Calcareous
shale

 

 

F— 60
20 ——

egim
0;

SEC. 13,
Th2: iii, Calcareous
' '2 concretions
% 0 1KIL0METRE Bentonite
2 22

FIGURE 15.—Type section of the Cone Member of the Marias River
Shale and map showing line of measured section, sec. 13, T. 22 N.,
R. 1 W. Numbers on the left side of the column are key beds in the
measured section; numbers on the right side are USGS Mesozoic
collections. On the map, the arrow points upward stratigraphi—
cally; B, base, and T, top of member.

Type section of the Cone Member—Continued
Marias River Shale—Continued
Cone Member—Continued
13. Shale, etc—Continued
Mytiloides and numerous pelagic Forami-
nifera 2.0
12. Bentonite, dusky-yellow, limonitic, impure __ .1 .3
11. Shale, dark—gray, very calcareous, soft, papery;
weathers medium gray. Contains at least
two beds of very hard and distantly spaced
limestone concretions that are dark gray on
fresh fracture but light bluish gray where
weathered. The concretions range in size
from 2 cm thick and 5 cm in diameter to 5 cm
thick and 30 cm in diameter. Each is enclosed
by a softer limonitic rind 1—3 cm thick. The
concretions and the shale of the unit contain
minute white specks and the following fossils
USGS Mesozoic 10c. D558:
Mytiloides mytiloides (Mantell) s.l.
Watinoceras reesidei Warren
Scaphites delicatulus Warren

4.8 15.7

10. Limestone; weathers bluish; shaly; forms
ledge; contains fish scales, small oysters, and
fragments ofMytiloides mytiloides (Mantell)
s. 1. ____________________________________

9. Shale, medium-gray, calcareous, soft ,,,,,,,, .3
8. Limestone, argillaceous, somewhat shaly;
weathers gray; forms ledge. Abundant frag-
ments of small oysters and Mytiloides myti-
loides (Mantell) s. 1 _______________________ .1 .3
7. Shale, soft, calcareous; weathers light buff
gray
6. Bentonite, dusky-yellow, nonswelling ________ .2 .7

H
h;

44 BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

Type section of the Cone Member—Continued
Marias River Shale—Continued
Cone Member—Continued M Ft

5. Shale, dark-gray; weathers light blue; very
limy, in part an argillaceous shaly limestone;
contains abundant minute white specks and
pelagic Foraminifera. A 2-cm bentonite layer
43 cm from top. Basal 46 cm and uppermost
61 cm moderately hard and form low bluish-
gray ledges. Unit crowded with Mytiloides
mytiloides (Mantell) s. 1. USGS Mesozoic 10c.

D557 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 1.4 4.5

4. Bentonite, white, low-swelling ______________ .9 3.0

3. Shale, dark—gray, soft, papery, slightly cal-
careous to noncalcareous. At very top are
small light-gray-weathering limestone con-
cretions 2—5 cm thick and 8—10 cm in diame-
ter that contain poorly preserved and
crushed fossils ,,,,,,,,,,,,,,,,,,,,,,,,,,

USGS Mesozoic loc. D556:
Inoceramus sp.
Nymphalucina sp.
Sciponoceras gracile (Shumard)

2. Shale, medium-brownish—gray, soft, papery,
calcareous; basal 2—3 cm is limonitic and con—
tains soft white silty nodules. Contains
closely spaced lavender-gray-weathering
septarian limestone concretions commonly
0.4 m thick and 1 m in diameter and smaller
and harder light-gray weathering nonseptar-
ian concretions. The veins in the septarian
concretions are made up of a thin outer wall
of brown finely crystalline calcite and a thick
inner part of coarsely crystalline white cal-
cite; a few veins have still more coarsely
crystalline colorless to pale-bluish-gray ba-
rite deposited on the white calcite. Fossils are
rare and poorly preserved ________________ .5 1.8

USGS Mesozoic 10c. D555:
Inoceramus sp.
Sciponoceras gracile (Shumard)
Ichthyodectes sp. (scales)
Total Cone Member (rounded) zzzzzz 1 .0 5 .0
Floweree Member (uppermost bed):

1. Shale, dark-bluish—gray, fissile, noncalcareous;
few thin lenses of gray siltstone and fine—
grained sandstone _________________________ 1.1 3.5

3.7 12.2

FERDIG MEMBER
NAME AND DEFINITION

The name Ferdig Shale Member of the Marias River
Shale was given by us (Cobban and others, 1959, p.
2794) to a unit of gray firm noncalcareous shale that
contains numerous thin hard sandy partings and con-
cretions of gray- and yellow-weathering limestone and
red-weathering ferruginous dolostone. The term shale
is removed from the formal name. This member over-
lies the limy Cone Member and underlies the softer
and less sandy Kevin Member. The Ferdig Member
comprises the beds described by Cobban (1951a, p.
2191, 2192) as the equivalent of the Carlile Shale of

 

the Black Hills. The name is taken from the post office
of Ferdig in sec. 31, T. 35 N., R. 1 W., Toole County,
about 9.7 km (6 mi) north of the summit of the Kevin-
Sunburst dome (Sunburst quadrangle). The type sec—
tion is composite from exposures 5—8 km (3—5 mi)
northwest of Ferdig as well as from outcrops 13 km (8
mi) southeast of Ferdig.

’l'HICKNESS

The Ferdig Member is 68.6 m (224 ft) thick in its
type section in T. 35 N., R. 2 W., on the Kevin-
Sunburst dome. Wells drilled on both the east and west
flanks of this dome also show thicknesses of this order.
The member is about 70 m (230 ft) thick as far east as
the West Utopia oil and gas field 41.8 km (26 mi) east
of the top of the Kevin-Sunburst dome. On the South
arch the Ferdig Member thickens northwestward from
31 m (101 ft) at its outcrop, 4.8 km (3 mi) north of the
town of Sun River, to about 63 m (205 ft) in wells
drilled in the Pondera oil and gas field and 67—73 111
(220—240 ft) in wildcat wells drilled in the Pendroy—
Birch Creek area.

OUTCROI’ DISTRIBUTION

The Ferdig Member makes a wide concentric “ring”
around the outcrops of the Bootlegger, Floweree, and
Cone Members on the Kevin-Sunburst dome and
greatly strengthens the areal geologic expression of
the dome. In places this belt has a width of 11 km ( 7
mi), emphasizing the difficulty of obtaining an accu-
rate section.

The best exposure, from the top (unit 50 of the type
section) down to unit 15, is on the west-facing escarp-
ment extending through secs. 1, 12, and 13, T. 35 N., R.
2 W., where, because of the north dip, approximately
80 percent of the member can be seen in excellent de-
tail free of glacial cover. Another extensive exposure of
the middle part, from unit 36 down to unit 15, is in low
west-facing slopes along the east bank of the north fork
of Antelope Coulee from near the SW cor. sec. 19, T. 33
N., R. 1 E., northward through secs. 18, 7, and 6;
thence westward into sec. 1, T. 33 N., R. 1 W.; and
north again into sec. 36, T. 34 N., R. 1 W. Units below
unit 15 are exposed in places as along the south and
west sides of sec. 36, where the type section was com-
pleted.

The Ferdig Member also is exposed in the Sweet-
grass Hills. South of Kevin-Sunburst dome an inlier of
the upper part of the Ferdig Member occurs where the
Marias River has trenched into the Marias River sad-
dle, the west end of the exposure being where US.
Highway 91 crosses the river.

On the South arch the Ferdig Member crops out from

FERDIG MEMBER 45

Fort Benton on the Missouri River westward across the
southern part of the Tunis, Carter, and Dent Bridge
quadrangles. The outcrop pattern swings south a little
and crosses the northern part of the Great Falls quad-
rangle in the high country north of Lake Creek. The
outcrop continues westward across the northern part of
the Vaughn quadrangle and into the northeastern
corner of the Fairfield quadrangle. From there it ex-
tends southeast along the west side of Muddy Creek
valley to the Sun River—Muddy Creek divide in sec. 7,
T. 21 N., R. 1 E., and west up the Sun River 2—3 km
(1—2 mi) west of Fort Shaw. From the Sun River valley
the outcrops extend south through the western part of
the Cascade quadrangle.

In the Disturbed belt the Ferdig Member crops out
3.2 km (2 mi) northeast of Wolf Creek in the NWM; sec.
31, T. 15 N., R. 3 W., and near the Rocky Mountains
front from T. 20 N., R. 8 W., north through T. 28 N., R.
8 W., and northwest to the eastern boundary of Glacier
National Park.

GEN ERA 1. DESCRIPTION

On the Sweetgrass arch the Ferdig Member consists
of a lower dark-bluish-gray shale unit that contains
hard red-weathering concretions of ferruginous dolo-
stone, a medial gray sandy shale that contains gray-
and yellow-weathering calcareous concretions, and an
upper dark-bluish-gray shale unit with small gray cal-
careous concretions.

The lower unit, about 15 m (50 ft) thick, beds 1—15 in
the type section, is a rather firm dark-bluish-gray
shale that contains a few very thin sandy partings and
numerous beds of reddish—weathering concretions or
thin layers of ferruginous dolostone and limestone.
These concretions or layers are dark gray to dark olive
gray on fresh fracture and very fine grained and hard.
They weather from rusty brown to grayish red and
very dusky red. They are so abundant on the outcrops
near the crest of the Kevin-Sunburst dome that a red-
dish color is imparted to the hillsides. The concretions
may be readily seen on the hill east of US. Highway 91
about 0.6 km (0.4 mi) south of Four Corners in the
NW% sec. 3, T. 34 N., R. 2 W., and along the Kevin-
Oilmont road (Shelby quadrangle). On the South arch
the concretions can be seen along both sides of the val-
ley followed by US. Highway 89 and the Chicago,
Milwaukee, St. Paul and Pacific Railway northwest of
the town of Sun River (Vaughn quadrangle). They may
be seen also near US. Highway 2 along the southeast
boundary of Glacier National Park (Cobban, 1956, p.
1002, mileages 7.8, 8.4; p. 1004, mileage 10.5). In the
Glacier National Park area a bed of black, gray, and
greenish chert pebbles occurs in the ironstone unit
(Cobban, 1956, p. 1004).

 

Bentonite is sparingly present in the lower unit. A
gray to brownish bed 15—46 cm thick occurs 8.2 m (27
ft) above the base of the unit on the outcrops in the Sun
River—Power area on the South arch; this bed is pres-
ent also on the Kevin-Sunburst dome.

The medial part, about 46 m (150 ft) thick in the type
section (beds 16—42), is a resistant bluish—gray-
weathering shale that contains some thin layers of
sandstone and tends to form smoothly rounded poorly
vegetated slopes. Much of the surface is flecked by
small thin flakes of rusty iron-stained shale that ap-
pears to result from the oxidation of laminae of pyritic
shale or bentonite. These chips make about 25 percent
of the surface litter for a total of about 15 m of the
medial unit and provide a very useful widespread gross
characteristic for the recognition of this part of the
Ferdig. The sandstone, very fine grained and relatively
resistant, is present chiefly as individual wavy layers
or lentils an inch or less in thickness, though in places
in assemblages of a few feet, that are light gray (N6) to
light olive gray (5Y6/ 1) on fresh fracture and brownish
where weathered. Upper bedding surfaces are com-
monly ripple marked and may show well-preserved
tracks, trails, impressions, and burrows that appear to
have been made by small crustaceans, annelids, and
ammonites. The lowest of these sandstones is the thin
layer in bed 18, which seems to represent the north
wedge-edge of the bed capping the hill at triangulation
station Cone. Other distinctive features of the middle
part of the Ferdig Member are various concretionary
lithologies that occur in no other part of the Marias
River Shale, such as the layered concentric septarian
limestone masses in bed 20, and also the replacement
of bentonite by selenite in the upper part of bed 39.

On the Kevin-Sunburst dome a thin but very persis-
tent layer of conglomeratic sandstone marks the top of
the medial unit of the Ferdig Member. This layer (unit
42 of the type section and bed N of Erdmann and
others, 1947) consists of light-gray to light-olive-gray
very fine to fine-grained sandstone that contains
polished granules and small pebbles of black chert and
some pebbles of white, gray, brown, and green chert,
quartz, quartzite, and argillite. This pebbly layer,
0.3—5 cm thick, is irregularly bedded and commonly
contains trails and burrows of small organisms and
here and there a coprolite or an impression of a
scaphite. Locally the bed is represented by light-olive-
gray-weathering sandy calcareous concretions that
contain a sprinkling of pebbles on their upper surfaces.
In the type section this pebbly bed lies 60.7 m (199 ft)
above the base of the member and 8.2 m (27 ft) below
the top. This bed readily can be seen west of the
Kevin-Sunburst road 5—6 km (3.2—3.8 mi) north-
northeast of Kevin in the W1/2 sec. 13, T. 35 N., R. 3 W.

46

(Sunburst quadrangle). It possibly is equivalent to the
conglomerate unit in the Bighorn (Cardium) Forma-
tion of southwestern Alberta. The Bighorn Formation
has been recognized in wells in the Pincher Creek gas
field 26 km (16 mi) north of the international boundary
in sec. 24, T. 3 N., R. 29 W., 4th Meridian (Douglas,
1952, cross-section A—C); it has not been identified,
however, farther east in structurally higher areas on
the north extension of the Sweetgrass arch (Spratt,
1931, fig. 3).

In the Disturbed belt, about 3.2 km (2 mi) east-
northeast of Wolf Creek in the NW% sec. 31, T. 15 N.,
R. 3 W., a 6-m-thick ridge-forming bed of brownish—
gray sandstone lies at the top of sandy beds that seem
to be correlative with the medial unit of the Ferdig
Member of areas farther east. The sandstone is fine
grained, thin bedded, and ripple marked. It is capped
by a thin layer of coarser sandstone that contains gray
and green smooth argillite pebbles derived from the
Belt Supergroup of Precambrian age, gray and black
chert, and a few pebbles of light- to medium-gray
dolomite with crinoid columnals of possible derivation
from the Madison Limestone of Mississippian age.
Most pebbles are 1—2 cm in diameter, but some are as
much as 5 cm. The small pelecypod Cardium pauper-
culum Meek is abundant in the uppermost beds. This
fossil, together with the lithologic character and thick-
ness of the beds, suggests correlation with the Bighorn
(Cardium) Formation of the Crowsnest River area of
southwestern Alberta (Webb and Hertlein, 1934, fig. 2,
p. 1394—1396). The eastward thinning of the Bighorn is
well recognized in southern Alberta (Scruggs, 1956, p.
25—29). It is evident that eastward thinning also pre-
vails in Montana in beds at this horizon. The
mechanism of the thinning is believed to be onlap of
the strata onto the rising Sweetgrass arch; further ref-
erence is made to it in the discussion on the upper unit
of the member.

Thin pebbly layers characterize the medial unit at
several other localities. Wells drilled in an area about
40 km (25 mi) long, extending from the Brady oil field
northeast to the Marias River, consistently penetrate a
pebbly bed 30 In (100 ft) above the base of the Ferdig
Member. On the north side of Sun River 2.4 km (1.5
mi) north of Fort Shaw, a 3—5-cm-thick pebbly layer is
24 m (78 ft) above the base of the member.

The sandy medial unit of the Ferdig is well exposed
along US. Highway 91 from 1.5 to 3 km (1-2 mi)
northeast of Power (Vaughn quadrangle) and from the
same highway 13 km (8 mi) north of Shelby north-
northwestward for 3.2 km in secs. 4 and 9, T. 33 N., R.
2 W. (Shelby quadrangle).

The upper unit, 8.2—10.7 In (27—35 ft) thick on the

 

BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

north flank of the Kevin-Sunburst dome, is chiefly
dark-gray shale that contains a few thin beds of gray
concretionary limestone. The top consists of a persis-
tent layer of concretionary limestone 10—25 cm (4—
10 in.) thick that is olive gray where fresh and grayish
yellow to yellow brown where weathered. It has a con-
spicuous hackly fracture. This bed was mapped by
Erdmann, Gist, Nordquist and Beer (1947) and desig-
nated bed M. The most accessible place to see the upper
unit of the Ferdig is just west of the Kevin-Sunburst
road in the north center of sec. 13, T. 35 N., R. 3 W.
Here, about 3 m below the top, fossils of late Carlile
age (late Turonian) were collected. Not far away, in the
south center of sec. 12, fossils of very early Niobrara
age (early Coniacian) were collected 5.2 m (17 ft) above
the top of the Ferdig. There appears to have been con-
tinuous deposition from upper Ferdig into lower Kevin.
Comparison of the type section of the Ferdig Member
with a section measured by Lemke and Maughan in
the center ofthe N1/2 sec. 15, T. 21 N., R. 1 W., indicates
that much of the middle unit of the Ferdig is absent at
this locality on the South arch.

The contact of the. Ferdig Member with the Cone
Member is very sharp. The lower boundary of the Fer-
dig could not be determined in the type section owing
to poor exposures of the basal beds. On the basis of
correlation with sections on the South arch, only a few
feet of beds may be concealed. However, the base of the
Ferdig on the Kevin-Sunburst dome can be seen on the
south bank ofa coulee in the SW. cor. NE%SW% sec. 5,
T. 32 N., R. 1 E., where it is overlain by a few feet of
beds not observed at the Cone type section. This is
believed to result from the disconformity between the
Cone and Ferdig Members.

On the South arch the base of the Ferdig Member is
commonly marked by a thin layer of soft limonitic
siltstone 2—3 cm thick which may locally contain fish
teeth, small pebbles of black chert, and larger gray and
brown phosphatic pebbles. The basal bed with fish
teeth and pebbles can be seen along the county road 8.5
km (5.3 mi) southeast of Cascade in the SE%NE% sec.
20, T. 17 N., R. 1 E. On the Kevin-Sunburst dome the
boundary with the Kevin Member is drawn at the top
of the persistent concretionary bed M of Erdmann,
Gist, Nordquist, and Beer (1947). On the South arch
this contact is not so easily determined and is placed at
the change upward from nonbentonitic dark-gray
shale to medium-olive-brown shale with numerous
beds of bentonite.

In well cuttings the shale forming the upper part of
the Ferdig Member is slightly harder and darker than
that of the Kevin Member and may contain pyrite. In
addition the upper part of the Ferdig lacks bentonite

FERDIG MEMBER 47

whereas the lower part of the Kevin contains several
beds.
AGE ASSIGNMENT AND CORRELATION

Three faunal zones and possibly a fourth are known
from the Ferdig Member. The unquestioned zones are,
from oldest to youngest, Prionocyclus hyatti,
Scaphites nigricollensis, and Scaphites corvensis
(Cobban and Reeside, 1952, correlation chart). The
questionable zone is that of Collignoniceras woollgari,
which is based on the impression of a single
juvenile ammonite that seems assignable to C.
woollgari (Mantell) var. regulare Haas. This impres-
sion is in a piece of ferruginous siltstone from near the
base (bed 2) of the type section of the Ferdig Member.
Because of the great variation within ammonite
species, additional material is needed before the zone
of C. woollgari can be stated definitely as present in
the basal Ferdig beds.

The zone of Prionocyclus hyatti can be demonstrated
for at least the upper part of the lower or dolostone-
bearing part of the Ferdig Member. Poorly preserved
juveniles of this ammonite have been found in dolo—
stone at many localities on the South arch and Kevin-
Sunburst dome. Scaphites carlilensis Morrow, a guide
fossil for this zone, was collected from bed 12 of the
type section. Scaphites carlilensis and Prionocyclus
hyatti are restricted to late Turonian rocks equivalent
to the Blue Hill Shale Member of the Carlile Shale of
Kansas.

The late Turonian ammonite Scaphites nigricollen-
sis is the next youngest species known from the Sweet-
grass arch. In the type section of the Ferdig Member,S .
nigricollensis has been found in the middle part (beds
26—36) of the medial unit associated with Baculites
yokoyamai Tokunaga and Shimizu. Over much of the
western interior region between the Black Hills of
South Dakota and the San Juan Basin of northwestern
New Mexico, three zones of ammonites (S caphites war—
reni, Scaphites ferronensis, and Prionocyclus
wyomingensis wyomingensis) lie between the zones of
Prionocyclus hyatti and Scaphites nigricollensis. Fos—
sils indicative of these three zones have not been found
on the Sweetgrass arch, and the time span of these
zones is probably represented by a hiatus. The middle
unit of the Ferdig is correlated with the upper part of
the Turner Sandy Member of the Carlile Shale of the
Black Hills. Equivalent rocks seem to be absent in
Kansas.

The top bed of the middle unit of the Ferdig Member
(bed 42 of the type section) and the overlying upper
unit of the Ferdig lie in the latest Turonian zone of
Scaphites corvensis. This part of the Ferdig correlates
with the Sage Breaks Member of the Carlile Shale of

 

the Black Hills.
Type section of the Ferdig Member

[Measured by C. E. Erdmann beginning 7.4 km (4.6 mi) north-northwest of Ferdig in the
NE%SW% sec. 1, T. 35 N., R. 2 W., Toole County (Sunburst quadrangle). The section
extends south through sec. 12 into the SW‘ANW‘A sec. 13, T. 35 N., R. 2 W., and termi-
nates in sec. 36, T. 34 N., R. 1 W. (fig. 16). The original field measurements were in feet
and inches]

M Ft
Marias River Shale:
Kevin Member (basal bed):
51. Shale, olive-gray, flaky, noncalcareous ,,,,,, 2.5 8.3
Ferdig Member:

50. Limestone, olive-gray, concretionary, hard,

aphanitic; weathers grayish yellow to mod-

erate yellowish brown; surface rough,

hackly, with epigenetic prismatic structure;

a continuous resistant layer making struc-

tural benches. Bed M of Erdmann and others

(1947) __________________________________ .2 .5
49. Shale, gray, fissile ________________________ 4.6 15.0
48. Limestone, dark-gray, concretionary; shat-

tered noncontinuous discoid masses 30—40

cm in diameter __________________________ .1 .2
47. Shale, gray, fissile, as above ________________ 1.2 4.0
46. Shale, dark-gray, fissile; contains small discoid

septarian concretions of dark-gray limestone

weathering light olive gray ______________ 7 2.3

45. Shale, dark-gray; as above, but without
concretions ______________________________ .6 2.0
44. Limestone, dark-gray, concretionary, septar-
ian, much shattered; weathers light yel-
lowish gray. Makes small mounds with
diameter of 0.8 m at infrequent intervals, but
horizon is locally persistent. Fossiliferous " .1 .3
USGS Mesozoic loc. 20912:
Inoceramus sp.
"Martesia" sp.
Scaphites sp.
43. Shale, dark-gray; a few thin concretions of
gray limestone about 20 cm above base of
bed. Slope heavily littered with small thin
brown chips ______________________________ .8 2.7
42. Sandstone, light-gray to gray, very fine- to
fine-grained; upper surface sprinkled with
rounded, polished granules of black chert and
accessory gray chert, quartz, and arg‘illite
with thin black patina. Bed N of Erdmann,
Gist, Nordquist, and Beer (1947) ,,,,,,,,,, .1 .2
USGS Mesozoic locs. 20911 and D1256
Inoceramus sp.
Scaphites coruensis Cobban
S. corvensis var. bighornensis Cobban
Prionocyclus sp.
41. Shale, brownish-olive—gray, noncalcareous,
soft, flaky; a few thin ochreous yellow and
brown laminae. A 1-cm-thick bed of rusty

bentonite at base ________________________ 1.6 5.2
40. Shale, dark-gray, soft, fissile; scattered flat,

oval (20 by 40 by 5 cm) septarian concretions

of gray limestone ________________________ 2.7 8.8

39. Bentonite, gray, soft, sandy textured; weathers
light yellowish gray and moderate yellow to
dark yellowish orange; in places replaced by
caramel-brown-weathering prismatic calcite,

48

   

BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

—20912

 

 

 

 

—01252

~01251

“01250
- -DIZ49

 

 

~20911,01256

Chert pebbles

(I)
m
3
Q.
m
,_,
O
3
m

‘2’
r:
m
H
O
:3
to

Shale

0
0

Q

Calcareous and
Iron stone concretions

E

Bentonite

METR ES FEET

 

o —‘ 0
—~ 20
— so
7 so
20 7
1 MlLE
o 1KILOMETFlE
R 'lW.

 

T. 34 N.

 

 

 

 

 

 

 

 

Type section of the F erdig Member—Continued

Marias River Shale—Continued
Ferdig Member—Continued

39. Bentonite, etc—Continued
with development of incipient cone-in-cone
and gnarly structure, and further local
epigenetic development of selenite rosettes in
upper part. Bed is lenticular, breaking up
into discrete concretionary masses, but is
persistent ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
38. Shale, gray, flaky; contains at base gray lime-
stone concretions 1 by 2.5 by 0.3 m at inter-
vals of 15—30 m __________________________
37. Shale, dark—gray; contains thin stringers and
laminae of fine-grained gray sandstone and
ferruginous siltstone _______________________
36. Shale, dark-gray, fissile; 0.3-0.6-cm-thick
layers of yellowish-gray siltstone and gray
fine-grained sandstone at intervals of 15 cm
or less. Scattered discoid septarian concre-
tions of gray fossiliferous concretionary lime-
stone at base ____________________________
USGS Mesozoic loc. 23666:
Baculites sp.
Scaphites nigricollensis Cobban
S. nigricollensis var. meeki Cobban
35. Shale, dark-gray, fissile; in beds 20—25 cm
thick parted by thin 0.5-cm—thick laminae of
fine-grained gray sandstone ,,,,,,,,,,,,,,
34. Shale, dark-gray; contains yellowish-gray-
weathering septarian limestone concretions
10—50 cm in diameter and 520 cm in thick-
ness ____________________________________
33. Shale, dark-gray ,,,,,,,,,,,,,,,,,,,,,,,,,,
32. Shale, brownish-olive-gray; contains thin
layers of ferruginous siltstone and a 2-
cm-thick layer of bentonite near top ______
31. Shale, brownish-olive-gray', middle part con-
tains small concretions of fossiliferous gray
limestone ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
USGS Mesozoic loc. D1255:
Inoceramus sp.
Scaphites nigricollensis Cobban
S. pisinnus Cobban
30. Shale, brownish-olive-gray, silty, soft, noncal-
careous; contains a few very thin layers of
light-gray fine-grained sandstone and thin
layers of rusty-brown ferruginous siltstone.
A few concretions of fossiliferous limestone
at base __________________________________
USGS Mesozoic 10c. D1254:
Inoceramus cf. 1. fragilis Hall and
Meek

M Ft
3 1.0
6 2.0

10.5 34.3

1.1 3.6

1.5 5.0
.9 2.9
6 2.0

1.7 5.7
2 .8
6 2.1

 

FIGURE 16.—Type section of the Ferdig Member of the
Marias River Shale and map showing line of measured
section, sec. 36, T. 34 N., R. 1 W., and secs. 1, 12, and 13, T.
35 N., R. 2 W. Numbers on the left side of the column are
key beds in the measured section; numbers on the right
side are USGS Mesozoic collections. On the map, the
arrow points upward stratigraphically; B, base, and T, top

of member.

FERDIG MEMBER 49

 

Type section of the Ferdig Member—Continued Type section of the Ferdig Member—Continued
Marias River Shale—Continued Marias River Shale—Continued
Ferdig Member—Continued Ferdig Member—Continued M Ft
30. Shale, etc—Continued M Ft 19. Limestone, olive-gray (5Y 4/1), concretionary,
Baculites cf. B. besairiei Collignon aphanitic; weathers grayish yellow, with
Scaphites nigricollensis Cobban minor mottling by moderate to dark reddish
29. Shale, brownish-olive-gray; contains scattered brown. Locally persistent ,,,,,,,,,,,,,,,, 2 .8
small oval limestone concretions at top and a 18. Shale, dark-gray, noncalcareous, poorly ex-
thin rusty-brown siltstone layer in middle__ .5 1.6 posed, Contains a 3-cm-thick fine-grained
28. Limestone, dark-gray; weathers light gray; platy sandstone layer 0.5 m above base ____ 3.1 10.2
Concretionary, discrete oval septarian forms 17. Limestone, dark—gray, ferruginous, concre-
15 by 20 to 20 by 25 cm with partitions of tionary; weathers rusty brown with minor
light-brown calcite. In places rests on a very dusky red (maroon); flat, panlike masses
thin sandstone. Fossiliferous 77777777777777 .1 .2 1-1.5 m in diameter. Lower 10 cm stratified;
USGS Mesozoic loc. D1253: rest concretionary with prismatic structure;
Inoceramus Sp. discrete forms on about 15-m centers ______ 2 .5
Scaphites nigricollensis Cobban 16. Shale, dark-gray, moderately fissile, noncal-
27_ Shale, brownish—olive-gray; contains rusty- careous; weathers into thin flakes; contains a
brown-weathering very thin resistant layers few thin (0-5 cm) layers 0f gray 50ft fine-
of ferruginous siltstone ,,,,,,,,,,,,,,,,,, 2.7 8.7 grained sandstone ———————————————————————— 3-7 12-0
26. Limestone, dark—gray, concretionary; masses 15~ Dolostone, dark-gray, concretionary, ankerit—
of shattered angular fragments which weath- 10(7), very hard, aphanitic; weathers brown to
er orange, brown, and dusky red and whose dark brown; small noncontinuous much-
centers commonly remain gray. Locally shattered oval masses. Cores of massive
developed ________________________________ .2 .5 maroon—weathering dolostone are enclosed in
USGS Mesozoiciloc. 23667: thin Chippy dolostone weathering moderate
Baculites cf. B. besairiei Collignon brown —————————————————————————————————— 1 -2
Scaphites nigricollensis Cobban 14. Shale, dark-gray, moderately fissile, noncal-
S. nigricollensis var. meeki Cobban cereous —————————————————————————————————— 12 3~8
25. Shale, dark-gray; weathers bluish; contains a 13~ Shale, dark—gray, noncalcareous, poorly fissile.
few small (diameter 15—20 cm) oval septarian Contains dusky-red-weathering concretions
concretions of gray limestone ______________ 1.6 5,1 of hard dolostone at top and at 0.5, 1.3, and
24. Limestone, dark-gray, concretionary, ferrugi— 2-3 m above base ———————————————————————— 3~3 10-7
nous; weathers predominantly maroon (dark 12. Dolostone, olive-gray (5Y 4/1); weathers mod-
reddish brown, 10R 3/4, to very dusky red, erate brown to very dusky red (maroon); con-
10R 2/2) with minor crusts of moderate yel- cretionary, syngenetic, in discrete but nearly
lowish brown (IOYR 5/4) to dark yellowish coalescent oval forms as much as 40 by 55 cm
orange (lOYR 6/6) concentric about the ma- in diameter supporting a small bench ,,,,,, 1 .3
roon. Centers commonly light-yellowish-gray USGS Mesozoic loc. D1252:
septarian limestone. Discrete masses as Scaphites carlilensis Morrow
much as 1 m in diameter making low mounds 11. Shale, medium-dark-gray, flaky, noncalcare-
on 3—4 m centers ________________________ .1 .4 ous ______________________________________ 1 5 5.0
23. Shale, medium-dark-gray (N5), moderately fis— 10. Shale, medium-dark-gray, noncalcareous; a
sile, noncalcareous; poorly exposed in slope“ 4.9 16.0 thin bentonite in middle and at top ,,,,,,,, 6 2.1
22. Limestone, dark-gray, concretionary, clayey; 9. Bentonite, yellowish-gray (5Y 8/1); weathers
weathers tan to dark yellowish orange (10YR dark yellowish orange ____________________ 1 .3
6/6). Continuous resistant layer with pris- 8. Shale, medium-dark-gray, noncalcareous ____ 1 8 6.0
matic structure at top, locally slabby, mak- 7. Limestone, concretionary, dark-olive-gray; fer-
ing ledges, benches, or dip slopes. Small flat ruginous; weathers moderate brown; breaks
concretions of dark-gray ferruginous aphani- down into Chippy fragments in inconspicuous
tic limestone weathering orange brown rest mounds 0.3 by 1 m; fossiliferous __________ 1 .3
on top with irregular spacing and make low USGS Mesozoic loc. D1251:
Chippy mounds __________________________ .2 .5 Inoceramus cf. 1. fragilis Hall and
21. Siltstone, dark-olive-gray, poorly fissile, non- Meek
calcareous, finely micaceous. Surface littered Scaphites sp.
with small rusty fragments ______________ 3.4 11.0 6. Shale, medium-dark‘gray, noncalcareous ____ 1.1 3.5
20. Siltstone, dark-olive-gray; as unit 21. Scat- 5. Limestone, brownish-black;weathers dark yel-
tered throughout at irregular vertical and lowish brown and dusky red; concretionary;
horizontal intervals are very finely crystal- sandy texture. Inoceramus sp. ____________ 1 .2
line light-olive-gray septarian limestone 4. Shale, medium-dark-gray, flaky, noncalcare-
concretions weathering yellowish gray and ous ______________________________________ 3.6 11.7
having a thickness of 0.3 m and a diameter of 3. Limestone, olive-gray; weathers yellowish
1 m ____________________________________ 1.8 6.0 gray; weathers rusty where locally ferrugi-

50

Type section of the Ferdig Member—Continued
Marias River Shale—Continued
Ferdig Member—Continued
3. Limestone, etc—Continued M Ft

nous; concretionary; flat, discrete oval forms

0.5—0.6 m in diameter, with radial and con-

centric structure developed by septae of

white and light-brown calcite. Sparingly fos-

siliferous in softer silty brecciated outer

crust. Widely spaced; usually much shat—

tered, making inconspicuous chunky mounds .1 .3

USGS Mesozoic 10c. D1250:

Inoceramus fragilis Hall and Meek
Collignoniceras sp.
Ichthyodectes sp. (scales)

2. Shale, medium—brownish-olive-gray,
noncalcareous. A thin yellowish-orange-
weathering ferruginous fossiliferous
siltstone layer at base ,,,,,,,,,,,,,,,,,,,, .6

USGS Mesozoic loc. D1249:
Collignoniceras cf. C. woollgari
(Mantell) var. regulare Haas

1. Shale, medium»brownish—olive-gray, noncal-

careous, papery ,,,,,,,,,,,,,,,,,,,,,,,,,, .9 3.0

fissile,

2.1

Total measured Ferdig Member
(rounded) ,,,,,,,,,,,,,,,,,,,,,,,,,, 69.0 224.0
Base concealed by alluvium

KEVIN MEMBER
NAME AND DEFINITION

The Kevin (pronounced Kee-vin) Member of the
Marias River Shale was named by us (Cobban and
others, 1959, p. 2797) for the very good exposures a few
kilometres north and northwest of the town of Kevin
on the northwest side of the Kevin-Sunburst dome. The
type section was measured in the N1/2 T. 35 N., R. 3 W.
(fig. 20), the same township in which Kevin is located.
The member consists of dark-gray marine shale that
contains some thin sandy partings, numerous thin
layers of bentonite, and many beds of calcareous con-
cretions weathering gray, yellow, or red; the term
shale is removed from the formal name. This is the
member of the Colorado Shale described by Cobban
(1951a, p. 2193—2195) as equivalent to the Niobrara
Formation of the Black Hills.

THICKNESS

In its type section on the northwest side of the
Kevin-Sunburst dome the Kevin Member is about
189 m (620 ft) thick. It thickens westward to 213 m
(700 ft) in the Cut Bank oil and gas field. Eastward
from the type section, the thickness changes very little.
It is 177 m (580 ft) thick in the West Utopia oil and gas
field in T. 33 N., R. 4 E., and 171 m (560 ft) thick in the
Bears Den oil field in T. 36 N., R. 6 E. On the South
arch the Kevin thickens westward from 203 m (665 ft)
a few kilometres north of the Pondera oil field to 232 m

 

 

BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

(760 ft) in wells drilled at the eastern edge of the Dis-
turbed belt.

()L'TCROP DISTRIBUTION

The Kevin Member has the greatest outcrop area of
any of the members of the Marias River Shale. It forms
the bedrock on the crest of the Sweetgrass arch begin-
ning at a point 24 km (15 mi) north of Great Falls and
extending northwest and north beyond Shelby. On the
flanks of the Sweetgrass arch the Kevin crops out from
Cascade northward to about one kilometre (within a
mile) of the international boundary and southeast from
there to Fort Benton. The member is exposed also
around the flanks of the Sweetgrass Hills. In the Dis-
turbed belt the Kevin crops out in a narrow
northwest-trending belt about 16 km (10 mi) long
north and east of Wolf Creek and a much larger area
bordering the Rocky Mountain front from Sun River to
the international line.

(IEN I‘ZRAI. DESCRI I’I'ION

The Kevin Member can be subdivided into three
units on the basis of the abundance of bentonite and
the type of concretions. The lowest unit is correlated
with the Fort Hays Limestone Member of the Niobrara
Formation of the central Great Plains, and the middle
and upper units are correlated with the lower and mid-
dle parts of the Smoky Hill Chalk Member of the Nio-
brara Formation of the central Great Plains.

The lowest unit, 53—55 m (175—180 ft) thick, is
characterized by many beds of bentonite, calcareous
concretions, and concretionary limestone. It includes
beds between I and M of Erdmann, Gist, Nordquist,
and Beer (1947). Most of the concretions in the unit are
composed of oval masses of limestone that are dark
gray on fresh fracture and medium light gray to yel-
lowish gray where weathered. They range in size from
5—30 cm (2—12 in.) in thickness and 10—50 cm (4—20 in.)
in diameter. Many are highly fossiliferous. Along the
Marias River 8 km (5 mi) south of Shelby, brown-
weathering ferruginous concretions, not present in the
type section, occur in the lower part of the unit. In the
upper part of the unit beds of hard gray aphanitic lime-
stone consist of concretionary lenses 15-75 cm (6—30
in.) thick and 1—3 m long. Some of the limestone is
septarian with veins of brown or white calcite. Gnarly
cone-in-cone structure characterizes a few of the beds.
Two conspicuous beds of limestone mapped by
Erdmann, Gist, Nordquist, and Beer (1947) were des-
ignated beds J and K. Sandstone beds, a very minor
constituent in the unit, are thin, very fine grained, and
shaly, and they weather brown. Some have borings and
trails made by small marine organisms. Bentonite is
abundant; 20 layers 2—35 cm (1—14 in.) thick are pres-

KEVIN MEMBER 51

ent in this unit in the type section. Yellowish-brown-
weathering prismatic calcite associated with two of the
beds of bentonite were mapped by Erdmann, Gist,
Nordquist, and Beer (1947) and designated beds I and
L. The many layers of light-gray bentonite impart a
banded appearance to the outcrops; this feature can be
seen in figure 17.

This lowest unit of the Kevin Member can be seen
readily along the county road 3.2 km (2 mi) north of
Fort Shaw (Fairfield quadrangle), along U.S. Highway
91 about 6.4 km north-northeast of Power in the SW.
cor. sec. 6 and NW. cor. sec. 7, T. 23 N., R. 1 E. (Dutton
quadrangle), along the north bank of the Marias River
where it is crossed by U.S. Highway 91 about 8 km (5
mi) south of Shelby, just out of Shelby on Highway 91
in SWIASWIA sec. 21, T. 32 N., R. 2 W., and at the type
section of the Kevin Member 4.8 km (3 mi) north-
northwest of Kevin. Cobban (1956, p. 1004) has drawn
attention to outcrops along the southeast side of
Glacier National Park.

Above the bentonitic unit with its gray limestone
concretions and concretionary limestone is a unit of
shale about 61 In (200 ft) thick that is characterized by
numerous beds of reddish—weathering ferruginous con—
cretions and concretionary limestone and dolostone. It
includes the rocks from bed I to about midway between
beds D and E of Erdmann, Gist, Nordquist, and Beer

 

(1947; beds 58—143 of type section). The beds and con-
cretions of limestone, commonly with gnarly cone-in-
cone structure at the top, are dark gray to olive gray
where fresh and yellowish gray to yellowish brown
where weathered. The dolostone is ferruginous and oc-
curs as concretions or concretionary layers which
weather reddish brown to very dusky red. The beds of
limestone commonly are 30 cm thick whereas the beds
of dolostone rarely exceed 10 cm in thickness. Very
thin layers of gray to olive-gray sandstone occur here
and there. The sandstone is very fine grained, weath-
ers brownish, and in places contains borings and trails
of small marine organisms. A few thin layers of bento-
nite are present.

An important marker bed, bed F of Erdmann, Gist,
Nordquist, and Beer (1947), lies near the middle of the
red concretion unit. This bed was first noted in geologic
literature by Clark (1923, p. 267) as “the yellow lime
chert conglomerate.” It is a conglomeratic bed of dolo-
stone and limestone that weathers light brown, orange
brown, and very dusky red. It contains polished
rounded granules and small pebbles of gray and black
chert as much as 2 cm in diameter and larger pebbles
of light-olive-gray, medium-olive—gray, and medium-
gray phosphatic siltstone as much as 5 cm in diameter.
The phosphatic pebbles are much more numerous than
the chert pebbles. A few dark phosphatic pebbles were

 

FIGURE 17.—Numerous thin beds of white bentonite in the lower part of the Kevin Member of the Marias River Shale in the SW%
SW1/4 sec. 18, T. 31 N., R. 2 W., Toole County, Mont.

52 BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

originally small pelecypods or parts of ammonites.
Koskinen (1951) has described this bed in further de-
tail. The structure Of many hundreds of square miles of
the Kevin-Sunburst dome was mapped by means of
this thin but distinctive pebbly bed. Reconnaissance
shows that the bed is present from the Rocky Moun-
tains front eastward across the Sweetgrass arch to the
Bearpaw Mountains and southward from there at least
as far as Shawmut in south-central Montana. Because
of its widespread extent and ease of recognition, the
bed was named by us (Cobban and others, 1959, p.
2795) the MacGowan Concretionary Bed for exposures
on the MacGowan lease in the SE%SW%NE% sec. 4, T.
35 N., R. 3 W., about 8.5 km (5.3 mi) north-northwest
of Kevin in the Kevin-Sunburst oil and gas field (Sun-
burst quadrangle). Bed 100 (p. 58) which was meas-
ured at this locality, is the type section. Here the bed
is 0.5 m thick and lies in the middle of the Kevin
Member (96 m or 314 ft below the top). The interval
from the MacGowan Concretionary Bed to the top of
the Kevin Member may show much variation, as in the
SE%NE% sec. 31, T. 30 N., R. 3 E., where it is only
about 67 m (220 ft) thick, the decrease probably being
due to a hiatus and absence of up to 24 In (80 ft) of
strata in the upper part of the Clioscaphites
chateauensis zone, and perhaps another small hiatus
in the Scaphites depressus zone. One or two incon-
spicuous layers of phosphatic pebbles in places lie 3
short distance above the MacGowan Concretionary
Bed. Three metres above the MacGowan Bed at its type
locality is a 2-cm-thick bed of rounded to subrounded
phosphatic siltstone and sandstone pebbles. These
pebbles are greenish gray (5GY6/1) to olive gray (5Y4/
1) with darker crusts, and some have a close irregular
light-gray reticulation. They range in size from 0.6—4
cm. On the south bank of the Marias River near the
center of the S1/2 sec. 17, T. 31 N., R. 3 W. (Valier
quadrangle) two layers of phosphatic pebbles are pre-
sent above the MacGowan Concretionary Bed. The
lower pebbles, 5.8 m (19 ft) above the MacGowan Bed,
consist of light-olive-gray glauconitic siltstone with an
outer dark-greenish-gray surface (5GY4/1) crossed by
irregular lighter greenish-gray (5G6/1 to 5GY6/ 1)
lines. These pebbles attain diameters up to 2.5 cm. The
upper pebbles, 10.4 m (34 ft) above the MacGowan Bed,
are smaller, darker, and lack the greenish cast of the
lower bed. They are dark gray (N3) with irregular
light-olive-gray (5Y6/1) lines on the outer surface.
Glauconitic, phosphatic pebbles similar to those of the
lower bed occur on the southeast flank of the South
arch 10.8 km (6.7 mi) northeast of Carter in the
SEMLSEM; sec. 16, T. 24 N., R. 7 E. (Tunis quadrangle).

The medial unit of the Kevin Member can be seen

 

readily a few kilometres northwest of Kevin at many
places in the NW% T. 35 N., R. 3 W., and T. 36 N., R. 3
W. (Erdmann and others, 1947). On the South arch the
unit is well exposed 0.8—3.2 km (0.5—2.0 mi) north of
US. Highway 87 from 24—113 km (1.5—7.0 mi) north-
east of Carter (Carter and Tunis quadrangles). In the
Disturbed belt easily accessible outcrops of these beds
are along the Burlington Northern Railway tracks
from the bridge over Two Medicine Creek (1.6 km or 1
mi northeast of East Glacier) northeastward for 6.4 km
(4 mi) (Marias Pass quadrangle).

Overlying the medial red concretion unit of the
Kevin Member is about 61 m (200 ft) of dark-gray
shale that contains many beds of yellowish—gray-
weathering concretionary limestone and a few thin
layers of shaly sandstone and bentonite. The upper
half or more of the shale is calcareous and, in places,
sandy. LimeStone occurs as concretionary lenses 2—60
cm (1—24 in.) thick and as much as 2.7 m (9 ft) in
diameter. The limestone is dark gray to olive gray
where fresh and yellowish gray to yellowish orange
where weathered. Some of the beds of limestone are
sandy and finely laminated. A few have cone-in-cone
structure. Sandstone is represented by thin more or
less shaly very fine-grained beds that weather yel-
lowish gray. A few thin beds of bentonite are present.
Thin layers of light-gray calcite occur in abundance
associated with one of the beds of bentonite (bed A of
Erdmann and others, 1947; bed 178 of type section)
about 9 m (30 ft) below the top of the Kevin Member.

The boundary between the Kevin Member of the
Marias River Shale and the overlying Telegraph Creek
Formation (basal unit of the Montana Group) is very
sharp on the west flank of the Kevin-Sunburst dome
and can be recognized on the basis of both color and
lithology (fig. 18). The highest bed (top of unit 187) is a
thin persistent bentonite that commonly is obscured by
colluvium, at which places it may be traced by refer—
ence to the resistant chips of light-gray translucent
calcite from bed A (unit 178). The upper bentonite is
underlain by about 1.2 m of dark-olive—gray shale that
contains the “first white specks,” which are a widely
recognized subsurface marker for this horizon. South-
ward in Marias River valley, the color contrast in the
basal part of the Telegraph Creek Formation disap-
pears together with the shaly calcareous sandstone
(units 180, 183, and 184), but the upper bentonite and
bed A persist.

The best outcrops of the upper unit of the Kevin
Member are north and northwest of Kevin, in Tps. 35
and 36 N., R. 3 W., and along the Marias River south-
west of Shelby, in the northern part of the Valier
quadrangle.

KEVIN MEMBER 53

 

FIGURE 18.—Upper part of Kevin Member of Marias River Shale (dark) overlain by lighter gray sandy Telegraph Creek Formation
and that, in turn, by thecliff—forming Virgelle Sandstone in the Nl/zNEMiNWM; sec. 24, T. 35 N., R. 4 W., Toole County, Mont.

AGE ASSIGNMENT AND CORRELATION

Most of the guide fossils from the Kevin Member
have been listed by Cobban (1951a, p. 2194, 2195).
They show that the member is of Coniacian and Santo-
nian age and correlated with most of the Niobrara
Formation of the central Great Plains.

The lower unit—characterized by many layers of
bentonite, numerous beds of gray concretionary lime-
stone, and the brown-weathering ferruginous concre-
tions in the Marias River valley—contains two faunas.
The lower part of the unit with the ferruginous concre-
tions contains a pelecypod close to if not identical to
Inoceramus erectus Meek and the ammonites
Scaphites preventricosus Cobban, S. preventricosus
var. artilobus Cobban, S. mariasensis Cobban, and S.
mariasensis var. gracillistriatus Cobban. The rest of
the unit contains I noceramus deformis Meek, Veniella
goniophora Meek, Baculites mariasensis Cobban, B.
sweetgrassensis Cobban, Scaphites preventricosus, S.
preventricosus var. sweetgrassensis Cobban, S. im-
pendicostatus Cobban, Pteroscaphites auriculatus
(Cobban), and Actinocamax n. sp. The entire unit is
correlated with the Fort Hays Limestone Member of
the Niobrara Formation on the basis of the presence of

 

I noceramus deformis in this limestone.

The middle unit, marked by the red ferruginous con-
cretionary limestone and dolostone and by the phos-
phatic pebble beds, contains three faunal zones. The
lowest embraces the rocks below the MacGowan Con-
cretionary Bed. Guide fossils to this zone include the
pelecypod Inoceramus (Volviceramus) involutus Sow-
erby (=Inoceramus umbonatus Meek and Hayden) and
the ammonites Scaphites ventricosus Meek and
Hayden and Scaphites tetonensis Cobban. The middle
zone, which includes the MacGowan Bed and the over-
lying shales with the phosphatic pebble layers, con-
tains I noceramus stan toni Sokolow, S caphites depres-
sus Reeside, and Scaphites binneyi Reeside. The upper
zone contains I noceramus (Cordiceramus) cordiformis
Sowerby, Clioscaphites vermiformis (Meek and
Hayden), and C. montanensis Cobban. All three zones
indicate correlation with the lower part of the Smoky
Hill Chalk Member of the Niobrara Formation. Cob-
ban, Erdmann, Alto, and Clark (1958, p. 658) have
pointed out that rocks containing the Scaphites
depressus fauna on the Kevin-Sunburst dome are not
known to exceed a thickness of 16.8 m (55 ft), whereas
in the Bighorn Basin of Wyoming the Scaphites depres-

54 BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

 

 

 

 

 

 

 

 

 

 

 

~01334
‘01333
01240, 01332

108

 

36

 

 

 

 

 

   
     
 
   

 

 

 

 

E
(I)
<3
:0
fir
20
m‘.’

C

Chert pebbles

m
m
3
Q
u:
H
O
3
(D

‘1’
z
m
A.
o
:1
('D

Shale

-
e

Limestone
Calcareous concretions

G
0

E

Bentonite

lronstone
concretlons

_L__l_
_|_

I

Calcareous
shale

METRES FEET
0-—'f0

llHl

_40

—-w

 

20-—

FIGURE 19.—Type section of the Kevin Member of the Marias River Shale and map showing line of measured
section, secs. 3, 4, 12, 15, and 17, T. 35 N., R. 3 W. Numbers on the left side of the column are key beds in the
measured section; numbers on the right side are USGS Mesozoic collections. On the map, the arrow points

upward stratigraphically; B, base, and T, top of member.

KEVIN MEMBER

sus fauna ranges through as much as 183 m (600 ft) of
the Cody Shale. The thinness of the rocks representing
this fauna on the Kevin-Sunburst dome together with
the presence of as many as three beds of phosphatic
pebbles suggest breaks in deposition or at least very
slow deposition.

The upper unit of the Kevin Member contains the
rest of the Clioscaphites vermiformis zone and two
younger zones, 3 lower marked by Clioscaphites
choteauensis Cobban and an upper characterized by
the ammonites Baculites thomi Reeside,Scaphites leei
Reeside, Clioscaphites novimexicanus (Reeside), and
Desmoscaphites erdmanni Cobban. These zones, for-
merly believed to represent the youngest part of Nio-
brara time, are probably of middle Smoky Hill age,
inasmuch as the upper part of the Smoky Hill Chalk
Member is now believed to be of early Campanian age
and to include rocks equivalent in age to the Telegraph
Creek and Eagle Formations (J eletzky, 1955). The
upper zone also contains I noceramus (Sphenoceramus)
lundbreckensis McLearn (1929, p. 77, pl. 15, fig. 4; pl.
16, fig. 2). This species may be the same as I. patooten-
siformis Seitz (1965, p. 107, pls. 20—25).

Type section of the Kevin Member
[Measured by C. E. Erdmann at the following localities in T. 35 N., R. 3 W., Toole County,
Sunburst quadrangle. Many other measurements also have been made but the strata are
best exposed at these localities. The original field measurements were in feet and inches
(fig. 19)]

Units (beds of Erdmann

and others, 1947) Locality
1 (base)—12 (L) ,,,,,,,,,,,,,,,,,,,,,,,, NE%SW% sec. 12.
12 (L)—40 (K) ,,,,,,,,,,,,,,,,,,,,,,,,,, North-center sec. 15.
40 (K)—51 (J) __________________________ SE%SW% sec. 3.
51 (J)—57 (l) ____________________________ NE'ASW‘Asec. 3.

57 (I)—81 (G)
81 (G)—100 (F)

__________________________ NW%SW%sec. 3.
________________________ NWMiSWM; sec. 3 to
SE%SE%NE% sec. 4
(type section
MacGowan
Concretionary Bed).

R.3W.

 

   

 

 

 

 

 

   

 

 

 

 

 

 

 

 

 

2 3 MILES

 

 

 

2 3 4 KILOMETRES

FIGURE 19.—Continued.

 

Type section of the Kevin Member—Continued

Units (beds of Erdmann

and others, 194 7)

Locality

100 (F)—124 ____________________________ NE‘ASE‘Asec. 4
(locality Scaphites
depressus zone).
124—156 (D) ____________________________ NEIANEMisec. 17.
156 (D)—187 (top) ______________________ NW‘ANE‘Asec. 1’7.

Telegraph Creek Formation (basal part):

189.
188.

Sandstone, buff (10YR 6/4), fine-grained ---_
Shale, pale-yellowish-brown (10YR 6/2).
Thinly laminated with fine sand ----------

Marias River Shale:
Kevin Member:

187.

186.

185.
184.

183.

182.

181.

180.

179.
178.

177.

176.

175.

174.

173.

172.

Shale, dark-olive-gray, fissile; some silt or
very fine sand. A 3-cm-thick ferruginous
bentonite bed at top. Horizon of ”first white
specks” ________________________________

Limestone, concretionary, olive-gray; weath-
ers yellowish gray; discrete oval masses as
much as 1 m in diameter in a nearly con-
tinuous bed. Contains Baculites sp., Ostrea
sp., and fragments of fossil bones ________

Shale, dark-gray, sandy, fissile ------------

Sandstone, gray, fine-grained; in thinly lami-
nated crossbedded layers with thin partings
of soft sandy shale. Makes a massive com-
paratively resistant ledge ----------------

Shale, dark—gray, sandy, thinly laminated;
contains a few thin layers of dark-gray
fine-grained sandstone. Transitional into
overlying unit --------------------------

Shale, dark-gray, sandy, thinly laminated;
contains scattered limestone concretions --

Shale, dark-gray, papery; more sandy toward
top

Sandstone, gray, soft, fine-grained, thinly
laminated, crossbedded; in thin 1—
5-cm-thick layers interlayed with minor
amounts of gray sandy shale ------------
USGS Mesozoic loc. 20695, 60 cm below top

of bed:
Ostrea sp.
Baculites n. sp. aff. B. haresi Reeside
Baculites thomi Reeside

Shale, dark-gray, fissile

Bentonite and calcite, light-gray; weathers
yellowish gray. Bed A of Erdmann, Gist,
Nordquist, and Beer (1947) --------------

Shale, gray, flaky; thin sandy layers and
laminae. A layer of thin discrete limestone
concretions occurs 1.5 m above base ------

Shale, dark-gray, fissile. A 6-cm-thick bento-
nite bed at base and a very thin bed at top

Shale, gray, soft, flaky. A 3-cm-thick gray
sandy thinly laminated limestone bed at
base ------------------------------------

Shale, gray, firm, calcareous, fissile ________

Limestone, gray, sandy. Makes a thin resist-
ant ledge

Shale, gray, firm, calcareous, flaky --------

M

0.3+

1.2

1.1

1.6

5.3

1.2

55

Ft
1+

1.2

4.1

1.0
6.0

1.0

2.0
3.8

3.0

5.2

1.8

17.5

4.0

17.1
1.5

31.5

56 BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

Type section of the Kevin Member——Continued
Marias River Shale—Continued
Kevin Member—Continued
172. Shale, etc—Continued
USGS Mesozoic loc. 20299, 1.5 m above the
base of this unit:
Inoceramus lundbreckensis McLearn
Pseudoperna congesta (Conrad)
Clioscaphites novimexicanus Reeside
Desmoscaphites erdmanni Cobban
171. Limestone, gray, sandy. Makes thin resistant
ledge. Thickness variable. Bed B of Erd-
mann, Gist, Nordquist, and Beer (1947) W
USGS Mesozoic 10c. D1237:
Inoceramus lundbreckensis McLearn
Pseudoperna congesta (Conrad)
Baculites thomi Reeside
Shale, gray, calcareous; contains small nodu-
lar concretions and a few thin (1 cm) layers
of gray sandy limestone __________________
USGS Mesozoic 100. 20690, 2.4 m above
base of this unit:
Pseudomelania n. sp. aff. P.
hendricksoni Henderson
Shale, gray, calcareous, nonfissile __________
Limestone, gray, sandy, concretionary. Local—
ly makes a thin ledge. Bed C of Erdmann,
Gist, Nordquist, and Beer (1947)
Shale, gray; small nodular concretions of gray
limestone
Shale, sandy; thin layers of sandstone 111111

170.

169.
168.

167.

166.

165. Shale, gray; numerous small (5—30 cm in
diameter) thin nodules of gray limestone __
Limestone, gray; concretions 1 m in diameter
Shale; thin layers of sandstone as much as 3
cm thick ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Shale, gray, sandy ________________________
Shale, gray, sandy; thin layers of fine-grained
gray sandstone __________________________
Shale, gray, nonfissile; weathers into granu—
lar fragments
Bentonite, rusty-brown, weathered ,,,,,,,,
Shale, gray, nonfissile; weathers into small
granular fragments ,,,,,,,,,,,,,,,,,,,,,,
Sandstone, gray, fine-grained; 1-cm-thick
beds interbedded with thin layers of sandy
shale __________________________________
Limestone, gray, concretionary, sandy, finely
laminated; weathers yellowish gray to
medium yellowish orange. Individual
masses as much as 3.5 by 2 m in plan, mak-
ing an almost continuous resistant layer,
with interstices occupied by gray shale. Bed
can be followed easily and makes a good
marker. Fossiliferous. Bed D of Erdmann,
Gist, Nordquist, and Beer (1947)
USGS Mesozoic loc. D1246:
Baculites asper Morton
B. codyensis Reeside
Clioscaphites vermiformis (Meek and
Hayden)
155. Shale, gray, soft, poorly exposed
154. Limestone, dark-gray; weathers yellowish
gray; concretionary: thin tabular masses,

164.
163.

162.
161.

160.

159.
158.

157.

156.

5.5

1.4

1.1
2.1

1.4

Ft

1.5

18.0

4.5

4.0
1.0

3.7
7.0

4.5

4.0

2.7

2.0

2.3

 

Type section of the Kevin Member—Continued

Marias River Shale—Continued

Kevin Member—Continued

154. Limestone, etc—Continued M

widely spaced. In a few places very fos-
siliferous
USGS Mesozoic loc. D1245:
Pseudoperna congesta (Conrad)
Baculites asper Morton
B. codyensis Reeside
Clioscaphites mon tanensis Cobban
C. vermiformis (Meek and Hayden)
153. Shale, gray, soft. At base a 6—cm-thick bed of
gray fine-grained soft sandstone __________ 1.3
152. Claystone, gray, nonfissile ________________ 2.6
151. Sandstone, gray, fine-grained, thinly lami-
nated, and crossbedded __________________ .1
150. Shale, gray, flaky, noncalcareous __________ .5
149. Limestone, gray, concretionary, very fine
grained; weathers yellowish gray; flat oval
masses 1 m in diameter, much shattered.
Locally one is larger, weathers yellowish
orange, and exhibits cone-in-cone structure.
Widely separated. Fossiliferous __________ .1
USGS Mesozoic 10c. 21666:
Inoceramus sp.
Baculites codyensis Reeside
Clioscaphites montanensis Cobban
C. vermiformis (Meek and Hayden)
148. Shale, gray, flaky ________________________ .6
147. Limestone, dark-gray, concretionary; weath-
ers yellowish gray; upper surfaces rounded;
aphanitic, hard, breaks with conchoidal
fracture; locally makes continuous layer
with minor development of cone-in-cone
structure. Fossiliferous ,,,,,,,,,,,,,,,,,, .2
USGS Mesozoic loc. D1244:
Membranipora sp.
Inoceramus n. sp.
Pseudoperna congesta (Conrad)
Baculites codyensis Reeside
Clioscaphites montanensis Cobban
C. vermiformis (Meek and Hayden)
146. Shale, gray, flaky, noncalcareous. At base is a
thin medium-olive-gray fine-grained finely
laminated sandstone bed containing a few
baculites ________________________________ 1.5
145. Limestone, concretionary; in thin, discrete
masses densely packed with Baculites
codyensis, replaced by white crystalline cal-
cite ____________________________________ .1
USGS Mesozoic loc. D1243:
Baculites codyensis Reeside
Clioscaphites montanensis Cobban
144. Shale, medium-dark-gray; contains a very
thin finely laminated layer of sandstone in
middle and a few small dolostone concre-
tions in lower 15 cm ____________________ 1.5
143. Dolostone, olive-gray, concretionary, hard,
aphanitic, fairly continuous; weathers
brown to very dusky red. Top of middle unit
of member ______________________________
142. Shale, brownish-olive-gray, soft, flaky ______
141. Dolostone, olive-gray, concretionary; weath-

Viki—l

Ft

4.2
8.5

2.0

5.1

4.8

Type section of the Kevin Member—Continued

Marias River Shale—Continued
Kevin Member—Continued

141.

140.

139.

138.
137.

136.

135.

134.

133.

132.
131.

130.
129.

128.

127.
126.

125.

124.

O

Dolostone, etc—Continued
ers brown to dusky red; small, infrequent
oval masses; very fossiliferous ____________
USGS Mesozoic 10c. 21665:
N uculana sp.
Inoceramus sp.
Baculites asper Morton
B. codyensis Reeside
Clioscaphites montanensis Cobban
C. vermiformis (Meek and Hayden)
Shale, brownish-olive-gray, soft, flaky; con-
tains a 3-cm-thick layer of bentonite ______
Limestone, dark—gray (N3), aphanitic, hard;
weathers yellowish gray (5Y 7/2). Contains
abundant baculites and a few fragments of
scaphites
Shale, olive-gray, flaky ,,,,,,,,,,,,,,,,,,,,
Limestone, gray, concretionary, ferruginous;
weathers yellowish gray ,,,,,,,,,,,,,,,,
Siltstone, brownish-olive-gray, noncalcare-
ous; weathers down into sharp granular
fragments and chips ____________________
Dolostone, olive-gray, concretionary, aphanit-
ic, hard; weathers reddish brown and dusky
red. Contains lentils of gray septarian lime-
stone with dark-brown calcite septae. A per-
sistent layer, making a small bench. Bed E
of Erdmann, Gist, Nordquist, and Beer
(1947) ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Shale, brownish-olive-gray, flaky, noncal-
careous; some thin sandy partings ________
Limestone, brownish-olive-gray, concretion-
ary; weathers light yellowish gray. Shat-
tered oval masses 1—2 m in diameter spaced
at intervals of 3—6 m. Very fine grained at
base, becoming prismatic toward top with
some gnarly cone-in-cone structure. A fairly
persistent bed __________________________
Shale, olive-gray, flaky, noncalcareous ,,,,,,
Limestone, gray, concretionary, ferruginous:
weathers brown to light yellowish brown.
Discrete tabular masses about 1 m in
diameter ________________________________
Shale, dark-gray, fissile
Limestone, olive-gray, dolomitic, concretion-
ary, aphanitic; weathers reddish brown and
very dusky red. Tabular masses 1 m or more
in diameter
USGS Mesozoic loc. 21664:
Inoceramus Sp.
Baculites sp.
Clioscaphites sp.
Shale, dark-gray, flaky, noncalcareous; be-
comes light olive gray toward top ,,,,,,,,
Shale, gray ______________________________
Limestone, gray, sandy; weathers yellowish
brown. Coquina type; many shell fragments
Shale, dark-gray; interlaminated with thin
brownish—gray siltstone __________________
Sandstone, medium-olive-gray, fine-grained,
hard, brittle, noncalcareous, very finely

KEVIN MEMBER

M

.1

1.0

2.4

4.6

1.7

Ft

.2

3.2

7.8

15.2

1.2
5.7

 

Type section of the Kevin Member—Continued

Marias River Shale—Continued
Kevin Member—Continued

124.

123.

122.
121.
120.
119.
118.

117.

116.

115.

114.

113.

112.

111.

110.

109.

108.

Sandstone, etc—Continued
laminated; weathers medium yellowish
brown __________________________________

USGS Mesozoic loc. D1242:
Inoceramus cf. I . cordiformis Sowerby
Baculites codyensis Reeside
Clioscaphites? sp.

Shale, medium-dark-gray, silty, noncalcare—
ous. A thin fine-grained sandstone bed at
base ____________________________________

Shale, brownish—olive—gray ________________

Bentonite, light-gray ______________________

Shale, brownish-olive-gray; as unit 119 ____

Shale, brownish-olive-gray. At top and base
are bentonite beds about 7 cm thick ______

Shale, brownish-olive-gray (between 5YR 4/1
and 5Y 4/1), noncalcareous, poorly fissile -1

Limestone, light-olive-gray, concretionary,
sandy textured, finely and evenly lami-
nated; weathers yellowish brown. Oval
masses 1—2 m in diameter, muchjointed and
shattered; spaced at intervals of 10 m or
more and may not be present in local sec-
tions __________________________________

USGS Mesozoic loc. 21663:
Inoceramus sp.
scaphite undet.

Shale, brownish-olive-gray, silty, soft, non-
calcareous, flaky ________________________

Bentonite, grayish-orange (10YR 7/4), granu—
lar textured, finely and smoothly laminated;
considerable biotite. Rests on 10 cm of hard
finely crystalline concretionary limestone
that weathers grayish to yellowish orange,
but which may be locally absent 1111111111

Shale, gray, flaky, noncalcareous __________

Sandstone, medium-gray, calcareous; firm,
relatively resistant, making a thin ledge.
Very fine grained; with wavy lamination
developed by short thin lentils of dark-gray
noncalcareous sandstone. Locally grades
laterally into circular masses of gray con-
cretionary limestone 1 by 2.7 m __________

Shale, dark-brownish-olive gray; a few thin
layers of fine-grained platy sandstone in
upper 1.2 m. Lower 2.1 m is dark gray (N3)
soft, fissile, noncalcareous ________________

Shale, medium- to dark-gray, flaky, noncal-
careous. A 6-cm-thick bed of bentonite at
top

Calcite and bentonite; grayish-orange, soft,
friable; medium— to coarse-grained con-
cretionary calcite and gray very micaceous
bentonite

Shale, olive-gray (5Y 4/1), soft, flaky, noncal-
careous, poorly exposed __________________

Phosphatic pebble bed. A concentration of
smooth rounded concretions of phosphatic
siltstone and sandstone, making a thin ar-
mored pavement-type surface over very lim-
ited areas, with here and there low mounds

57

M Ft
.1 .2
1.6 5.2
1.5 5.0
.1 .3
3.3 11.0
5 1.8
1.9 6.3
3 .9
4 1.2
.2 .7
3 1.0
2 .5
3.3 11.0
5 2.0
8 2.5
2.0 6.5

58

BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

Type section of the Kevin Member—Continued

Marias River Shale—Continued
Kevin Member—Continued

108.

107.

106.

105

104

103

102

101

100

Phosphatic pebble bed—Continued
that contain small oval limestone concre—
tions. The pebbles are greenish gray (5GY
6/1) to olive gray (5Y 4/1), with darker
crusts, and some have a close, irregular
light-gray reticulation. Size range: 5—40
mm, with mean 12—20 mm. All are rounded
or subrounded and a few spindle shaped;
many are broken, apparently along desicca—
tion cracks. Here and there a small scaphite
among the pebbles. Accessory limestone
concretions are of two types, both similar to
facies of the MacGowan Concretionary Bed:
(1) moderate yellowish-brown limestone in
nodules 15 by 10 by 5 cm, weathering dark
yellowish orange, and containing pellets of
light-gray phosphatic siltstone; (2) a single
discoid mass of ferruginous limestone 25 by
20 by 5 cm, weathering very dusky red
(10R 2/2) with small embedded pebbles as
above. Fossiliferous ______________________
USGS Mesozoic coll. D1334:
Inoceramus sp.
Scaphites sp.
Shale, olive-gray (5Y 4/1), soft, flaky, noncal-
careous
Limestone, moderate—brown to grayish-red,
concretionary, ferruginous; upper surface
very dusky red. Thin hard resistant layer
USGS Mesozoic loc. D1333:
Inoceramus stantoni Sokolow
Scaphites depressus Reeside var.
stantoni Reeside
Baculites asper Morton
Baculites codyensis Reeside
Shale, olive-gray, silty, soft, flaky. At base
was found a large fossil bone, probably a rib,
nearly 2 ft long
Limestone, olive-gray, concretionary, apha-
nitic; weathers moderate brown; uniform
persistent layer
USGS Mesozoic loc. D1240 and D1332:
Inoceramus sp.
Baculites asper Morton
Baculites codyensis Reeside
Scaphites depressus Reeside
Shale, medium-gray, noncalcareous, silty;
contains near top dusky-red-weathering
dolostone concretions ____________________
Dolostone, dark-greenish—gray to olive-gray,
concretionary, aphanitic; weathers very
dusky red (maroon); in small hard discrete
nodules as large as 8 by 15 cm. Sparingly
fossiliferous ____________________________
Shale, olive-gray (5YR 4/1), noncalcareous,
soft, poorly fissile. Thickness variable ____
MacGowan Concretionary Bed. Bed F of
Erdmann, Gist, Nordquist, and Beer (1947).
Type section.
100c. Dolostone, brownish-gray (5YR 4/1),
ferrug‘inous, hard; weathers dark reddish

.1

2.4

Ft

1.5

2.0

2.6

8.0

 

Type section of the Kevin Member—Continued

Marias River Shale——Continued
Kevin Member—Continued
1001c. Dolostone, etc—Continued

99.

98.

97.
96.

brown (10R 3/4) to very dusky red (10R 2/2);
aphanitic, breaking with subconchoidal
fracture. Matrix contains a few small pellets
(possibly reworked) of light-gray phosphatic
siltstone. Bed caps underlying limestone
concretions and fills interstices between
them __________________________________
100b. Limestone, brownish-olive-gray (be-
tween 5YR 4/1 and 5Y 4/1); weathers to
light orange brown (between 10YR 6/6 and
5YR 5/6) and shades of moderate brown
(5YR 4/4 and 5YR 3/4) with mottling or
splotches of moderate (10R 4/6) to dark
reddish brown (10R 3/4); concretionary,
conglomeratic; matrix aphanatic. A few
concretions remain predominantly gray,
weathering dull yellowish brown. Indi-
vidual forms are flat-based round-topped
fractured oval masses, noticeably septarian,
that vary in diameter from 30 to 50 cm and
are packed so closely as to form a continuous
layer. Conglomeratic facies consist of errat—
ic concretions and patches of irregularly
shaped smoothly rounded pellets of
yellowish—gray (5Y 8/1) to light-olive-gray
(5Y 6/1) phosphatic mudstone as long as 2
cm, although usually smaller; cover as
much as 10 percent or more of the outer sur-
faces of the concretions as crusts and are
embedded more sparingly in the matrix.
These pellets, with sharp color contrast to
the weathered surface, plus an accessory
sprinkling of 1 percent or less of smoothly
rounded well-polished pebbles of black to
olive-gray chert as much as 2 cm in diame—
ter, but usually much finer, are the princi-
pal diagnostic features of the bed. Entire
unit makes a thin resistent ledge capping
spurs or dip slopes, whose surfaces are par-
tially covered with a thin litter of angular
fragments ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
100a. Shale, dark-gray, noncalcareous, poorly
fissile. At base a thin concretionary light-
brown- to moderate-reddish-brown-
weathering bed of limestone. Base of Mac-
Gowan Bed

Shale, dark-olive-gray; a few thin laminae of
fine—grained chippy sandstone in middle and
at top __________________________________

USGS Mesozoic loc. D1238:
Inoceramus sp.

Shale, olive-gray (5Y 4/1); small thin widely
spaced septarian concretions of gray lime-
stone

Shale, gray, sandy, poorly exposed

Limestone, gray, concretionary; in thin flat
discoid masses 30 cm in diameter that
weather yellowish gray; dark-greenish-
olive-gray hard aphanitic dolostone, with
accessory marcasite and weathering dusky

M

bah;

Ft

1.0

1.3
2.1

KEVIN MEMBER 59

Type section of the Kevin Member—Continued
Marias River Shale—Continued
Kevin Member—Continued
96. Limestone, etc—Continued M
red and yellowish orange ________________ .1
USGS Mesozoic loc. 23753:
Inoceramus (Volviceramus) involutus
Sowerby
Pseudoperna congesta (Conrad)
Baculites sp.
95. Shale, gray; occasional discrete oval concre-
tions of dark-gray limestone, 30 by 15 cm,
that weather yellowish gray. At base a thin
lightolive-gray fine-grained soft finely
laminated sandstone bed ________________ .9
94. Limestone, olive-gray, concretionary, apha-
nitic; weathers yellowish gray; in discrete
oval masses 30 cm in diameter. Septarian
veins of dark calcite. Breaks into angular
fragments ______________________________ .2
93. Shale, gray; contains a very thin gray fine-
grained soft thinly laminated layer of
sandstone ______________________________ 1.3
92. Limestone, dark-gray, concretionary; weath—
ers lighter gray; small (diameter 30 cm)
oval septarian forms ____________________ .2
91. Shale, gray, silty, soft, noncalcareous ______ 1.7
90. Limestone, gray, concretionary, finely gran-
ular (sandy); weathers yellowish orange
and dark yellowish orange to yellowish
brown. Lower 15 cm may exhibit rude
cone-in-cone and prismatic structures.
Thickness 0.3—0.5 m, diameter 1—3 by 4.5 m.
Persistent, but occurring at large horizontal
distances
89. Shale, gray; as below ______________________ .3
88. Limestone, dull-red, concretionary, sandy;
makes persistent layer locally ____________ .1
USGS Mesozoic loc. D1331:
Scaphites ventricosus Meek and
Hayden
87. Shale, gray, soft, gypsiferous (radiating
fibrous selenite crystals). Contains a few
sandy ferruginous limestone concretions __ 2.2

86. Shale, dark—gray, soft, clayey; carries an occa-
sional concretion of ferruginous limestone
in lower 1.5 m. A very thin fine-grained
sandstone bed at top ,,,,,,,,,,,,,,,,,,,, 2.9

85. Limestone, gray; weathers buff to yellowish
gray; concretionary; in fairly large isolated
conspicuous masses making a small bench;
flat and slabby at base, discrete oval forms
at top; cone-in-cone structure in places W1- .1

84. Limestone, dark-gray; ferruginous, aphanitic;
weathers very dusky red. Fossiliferous “—4 .1

USGS Mesozoic loc. 20698:
Inoceramus (Voluiceramus) involutus
Sowerby
I noceramus (Volviceramus) undabundus
Meek and Hayden

83. Shale, gray, soft, clayey; contains a thin
gray—weathering limestone bed at base
overlain by a thin fine-grained sandstone

Ft
.3

3.1

4.3

1.5
1.0

7.4

9.6

 

Type section of the Kevin Member—Continued
Marias River Shale—Continued
Kevin Member—Continued
83. Shale, etc—Continued M Ft
bed. Actinocamax sp. ____________________ 1.9 6.2
82. Shale, gray, soft; makes slope; poorly exposed 3.7 12.3
81. Limestone, dark—gray, concretionary, fer-
ruginous, hard, aphanitic, persistent;
weathers very dusky red and dark yellowish
orange. Bed G of Erdmann, Gist, Nordquist,
and Beer (1947) ,,,,,,,,,,,,,,,,,,,,,,,, .1 .3
USGS Mesozoic loc. 20295:
Inoceramus sp.
Baculites sp.
Scaphites ventricosus Meek and
Hayden
80. Shale, gray, clayey, gypsiferous; contains
scattered thin sandstone and small oval
limestone concretions near middle and a
thin gray fine—grained chippy sandstone bed

at base ________________________________ 3.4 11.1
79. Shale, gray, soft, flaky ____________________ .2 .5
78. Limestone, dark-gray; concretionary, fer-

ruginous; weathers very dusky red; oval to

platy shapes; fairly continuous __________ .1 .2
77. Shale, gray, clayey; scattered concretions of

ferruginous limestone ,,,,,,,,,,,,,,,,,,,, 1.1 3.8

76. Limestone, dark-gray, concretionary, fer-
ruginous, aphanitic; weathers very dusky
red and brown; in large flat forms about 1 m
in diameter ____________________________ .1 .2
USGS Mesozoic loc. 20291:
Inoceramus (Volviceramus)
undabundus Meek and Hayden
Baculites asper Morton
Scaphites ventricosus Meek and
Hayden
Actinocamax sp.
75. Shale, gray, sandy, soft, flaky; contains a gray
fine-grained thinly laminated sandstone
layer at base ,,,,,,,,,,,,,,,,,,,,,,,,,,,, .6 2.0
74. Shale, dark-gray, clayey; contains a few small
nodular concretions of ferruginous lime—

stone weathering very dusky red ________ 1.8 6.0
73. Limestone, dark-gray, concretionary, ferru-

ginous; weathers very dusky red __________ .1 .3
72. Shale, dark-gray __________________________ .3 1.0

71. Limestone, dark—gray, concretionary, hard,
aphanitic, brittle; weathers very dusky red;
discrete masses commonly 30—50 cm long,
and smaller nodules. Fossiliferous. One con-
cretion contained a weathered bone nearly 1
m long and 15 cm in diameter ,,,,,,,,,,,, .1 .3
USGS Mesozoic loc. 20292:
Inoceramus (Volviceramus) involutus
Sowerby
I. (Volviceramus) undabundus Meek
and Hayden
Spondylus sp.
Baculites asper Morton
Scaphites ventricosus Meek and
Hayden
70. Shale, gray, soft, clayey ,,,,,,,,,,,,,,,,,, 1.1 3.5
69. Limestone, gray, concretionary; weathers yel-

60

68.

67.

66.

65.

64.
63.
62.
61.

60.
59.

58.
57.

56.

55.
54.
53.
52.

51.

50.
49.

BLACKLEAF AND MARIAS RIVER FORMATIONS, SWEETGRASS ARCH, MONTANA

Type section of the Kevin Member—Continued
Marias River Shale—Continued
Kevin Member—Continued
69. Limestone, etc—Continued

lowish gray; in discrete masses with poorly
developed cone-in-cone structure; resting on
thin gray sandy bentonite. Makes a persist-
ent marker. Bed H of Erdmann, Gist,
Nordquist, and Beer (1947) ______________
Shale, dark-gray, soft, clayey; checked sur—
face stained by white efflorescent salt -___
Shale, dark-gray, soft, clayey; contains a few
small oval concretions of limestone and thin
1—3-cm-thick gray chippy sandstones at
intervals of 50—60 cm ____________________
Shale, dark—gray, soft, clayey (bentonitic);
checked surface stained by white efflores-
cent salt ________________________________
Limestone, dark-gray, concretionary; oval
septarian masses about 30 cm long spaced
at intervals of 3 In ,,,,,,,,,,,,,,,,,,,,,,
Shale, dark-gray, soft, poorly fissile ________
Bentonite, gray, gritty; weathers tan ______
Shale, gray, soft, poorly exposed
Limestone, gray, concretionary, aphanitic;
oval septarian masses about 30 cm long
with much brown and white crystalline cal—
cite spaced at intervals of 1—6 m __________
Shale, gray, soft, poorly exposed
Bentonite, gray, sandy ____________________

Shale, soft, poorly exposed ,,,,,,,,,,,,,,,,
Calcite, light-yellowish-gray, sandy, prismat»
ic (fibrous); weathers tan to caramel brown;
poorly developed cone-in-cone structure.
Probably a calcareous replacement of a
layer of bentonite; fairly resistant, makes a
bench and caps small outliers. Bed I of
Erdmann, Gist, Nordquist, and Beer (1947).
Top of lower unit ,,,,,,,,,,,,,,,,,,,,,,,,
Siltstone, gray, noncalcareous, firm; brittle,
with a harsh feel; contains fossiliferous oval
concretions of gray aphanitic limestone
10—15 cm thick and 30—50 cm long in middle
part ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
USGS Mesozoic loc. 20696:
Inoceramus aff. I. corpulentus
McLearn
Ostrea n. sp.
Bentonite, gray l, ,,,,,,,,,,,,,,,,,,,,,,,,,,
Shale, gray ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Limestone, concretionary, gray; small rough
oval masses
Siltstone, gray, firm; harsh feel; weathers into
granular fragments ,,,,,,,,,,,,,,,,,,,,,,
Limestone, gray, concretionary, aphanitic;
weathers brownish; sandy at top, with some
gnarly cone-in—cone structure; in rounded
flat—topped much-fractured masses with
septae of brown calcite; commonly 1 m in
diameter but as much as 3 by 4 m. Makes
ledge in main slope. BedJ of Erdmann, Gist,
Nordquist, and Beer (1947) ,,,,,,,,,,,,,,,,
Shale, gray ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Sandstone, gray, fine-grained, thinly lami—
nated; weathers brownish; some shale part-

3.3

2.1

3.9

iei—chic

1.7

1.8

Ft

7.0

13.0

3.8

1.3

1.5

4.0

5.5

12.0

6.0

1.0
2.5

 

48.

47.

46.

45.

44.

43.

42.

41.

40.

39.
38.

37.
36.
35.
34.

33.
32.
31.
30.
29.
28.

27.

Type section of the Kevin Member—Continued
Marias River Shale—Continued
Kevin Member—Continued
49. Sandstone, etc—Continued

ings; bedding surfaces show worm (?) trails
and related markings ____________________
Limestone, gray, concretionary, aphanitic;
small flat oval forms. Contains Scaphites sp.
and Inoceramus sp _______________________
Shale, gray, soft, flaky; contains a few oval
concretions of gray limestone with frag-
ments of Scaphites sp.
Limestone, gray, concretionary, aphanitic;
small discrete masses at 6-m intervals. Con-
tains Inoceramus sp. and Ostrea sp. ______
Shale, gray, soft; poorly exposed on slope. A
3-cm—thick layer of bentonite at top ......
Bentonite, gray, sandy, weathered; at top a
thin layer of caramel-brown secondary
fibrous calcite; makes slight ledge ________
Shale, gray, soft; a few hand-sized concretions
of gray limestone; makes slope
Limestone, dark—gray, concretionary; weath-
ers light yellowish gray; in small 30—50-
cm-thick much-fractured oval masses with
septae of brown calcite; fossiliferous. Makes
a rather distinct bench ,,,,,,,,,,,,,,,,,,
Shale, gray, soft; poorly exposed on slope; con-
tains 6-cm-thick layers of bentonite at base
and middle _______________________________
Limestone, gray, concretionary, aphanitic,
gnarly; weathers rusty brown; veined with
more or less white crystalline calcite; hard,
resistant; massive discrete forms 0.5—3.0 In
in diameter spaced on 3—5-m centers mak-
ing small mounds. A conspicuous marker
bed. Bed K of Erdmann, Gist, Nordquist,
and Beer (1947)
Bentonite, sandy; weathered rusty
Shale, dark—gray, soft, clayey; contains a
3-cm—thick layer of bentonite at base ______
Shale, dark-gray, soft, clayey ______________
Bentonite, sandy; weathers rusty __________
Shale, gray, soft, clayey; makes slope ______
Limestone, gray, concretionary, fossiliferous;
in oval discrete forms as much as 50 cm long
USGS Mesozoic loc. 20300:
Scaphites sp.
Actinocamax sp.
Bentonite, gray, sandy; weathers rusty H"
Shale, gray, soft, clayey ,,,,,,,,,,,,,,,,,,
Limestone, concretionary, gray ,,,,,,,,,,,,
Bentonite, gray, sandy; weathers rusty A,"
Shale, brownish—gray, clayey, bentonitic ___,
Limestone, gray, concretionary, aphanitic,
hard, smooth; weathers yellowish gray; in
discrete oval forms 30 cm in diameter ,,__
USGS Mesozoic loc. 20296:
Inoceramus sp.
Ostrea sp.
Baculites mariasensis Cobban
Scaphites preventricosus Cobban
Actinocamax Sp.

Bentonite, gray, sandy; weathers rusty --.._

26. Shale, gray, flaky; top is silicified ,,,,,,,,,,

M

.4

3.8

1.2

'0:

2.5

i—ai—‘i—t'wi—A

Ft

1.3

12.5

4.1

2.0

8.4

2.6
10.5

3.0

1.2
1.5

REFERENCES CITED 61

Type section of the Kevin Member—Continued

Marias River Shale—Continued
Kevin Member—Continued M F!

25.
24.
23.
22.

21.
20.

19.
18.

17.
16.

15.

14.

13.

12.

11.
10.

Limestone, gray, concretionary, aphanitic;
small (diameter 30 cm) smooth discrete oval
masses

Bentonite, gray __________________________

Shale, dark-gray, soft, flaky. A very thin
layer of bentonite in middle ______________ 1.4 4.9

Bentonite, light-gray ,,,,,,,,,,,,,,,,,,,,,, .2 .5

Shale, dark-gray, soft, flaky

Limestone, dark-gray, concretionary; weath-
ers yellowish gray; smooth oval discrete
forms ___________________________________

USGS Mesozoic 10c. 20298:
Inoceramus deformis Meek
Pseudoperna congesta (Conrad)
Ostrea n. sp.

Pholadomya papyracea Meek and
Hayden

Veniella goniophora Meek

Drepanochilus? sp.

Baculites mariasensis Cobban

B. sweetgrassensis Cobban

Scaphites preventricosus Cobban

Shale, dark—gray, soft, flaky

Bentonite, rusty—brown, weathered; stain of
white efflorescent salt above bed 1111111111 .

Siltstone, dark-gray, soft; makes slope ______ 2.7 9.0

Bentonite, gray, sandy; weathers tan; upper
part of bed littered with caramel-color sec-
ondary prismatic calcite that has some

cone-in-cone structure ,,,,,,,,,,,,,,,,,, 3 1.0
Siltstone, dark-gray, soft; weathers into

gumbo with stains of white efflorescent salt.

Poorly exposed in slope __________________ 4.6 15.0

Bentonite, light-brownish-gray, sandy ______ .2 .5
Shale, dark—olive-gray, soft, flaky, noncal-
careous; contains a very thin rusty-brown
fine«grained finely laminated sandstone bed
near base ______________________________
Bentonite, yellowish—gray; contains much
light-brownish-gray (5YR 4/1) prismatic
calcite that has a tendency toward cone-in-
cone structure and weathers moderate yel-
lowish brown (caramel). A few small flat-
topped oval-shaped concretions of dark-
brownish-gray aphanitic limestone. Bed L
of Erdmann, Gist, Nordquist, and Beer
(1947) __________________________________ .3 1.0
Shale, dark-olive-gray, soft, noncalcareousr .4 1.3
Shale, brownish-gray, clayey, bentonitic. A
6—cm-thick pale-yellowish-brown micaceous
bentonite bed at base ____________________

4.0 13.1

. Shale, dark—gray, soft, poorly fissile, noncal-

careous

. Siltstone, dark—gray, soft; weathers brownish .4 1.3
. Limestone, dark-gray, aphanitic, concretion-

ary, hard, fetid-smelling, fossiliferous;

weathers light yellowish gray; in discrete

oval types (30 cm in diameter) in places sep-

tariate with veins of white and brown crys—

talline calcite; spaced at intervals of about

3 m ____________________________________ .1 .4
USGS Mesozoic 10c. 20289:

 

Type section of the Kevin Member—Continued
Marias River Shale—Continued
Kevin Member—Continued
7. Limestone, etc.——Continued M Ft
Anomia cf. A. subquadrata Stanton
Inoceramus sp.
Scaphites preuentricosus Cobban
S. preventricosus var. sweetgrassensis
Cobban
6. Siltstone, dark-gray, poorly fissile, soft, non-
calcareous; weathers into small granular
particles; some thin rusty laminae ________ 2.9 9.5
5. Limestone, dark-gray, concretionary; weath~
ers medium olive gray to light yellowish
gray; almost a continuous bed of small (di-
ameter 30 cm) closely packed discrete sep-
tarian masses that have rough upper sur-
faces and partitions of white calcite ______ .2 .5
USGS Mesozoic loc. D1247:
Inoceramus sp.
Oxytoma sp.
Tessarolax hitzii White
4. Siltstone, medium-dark-gray, noncalcareous;
contains small (10-cm-thick) nodules of gray
clayey limestone ,,,,,,,,,,,,,,,,,,,,,,,, .5 1.5
3. Siltstone, medium—dark-gray, noncalcareous.
Surface littered with thin rusty-brown chips
of clay ironstone. Unit also contains small
l-cm-thick irregularly shaped nodules or
concretions of soft moderate—yellow silt,
weathering dusky yellow, that have the
same shapes and appearance as kernels of

buttered popcorn ________________________ 1.6 5.3

2. Bentonite, yellowish-gray (5Y 8/1), sandy,
highly weathered ________________________ .2 .5

1. Siltstone, dark-gray, noncalcareous, poorly
fissile. Base of Kevin Member ,,,,,,,,,,,, 2.9 9.6
Total Kevin Member (rounded) 11111111 188.0 617.0

REFERENCES CITED

Bartram, J. G., and Erdmann, C. E., 1935, Natural gas in Montana,
in Geology of natural gas: Am. Assoc. Petroleum Geologists
[June], p. 245—276.

Blixt, J. E., 1941, Cut Bank oil and gas field, Glacier County, Mon—
tana, in Levorsen, A. L, ed., Stratigraphic type oil fields: Am.
Assoc. Petroleum Geologists [Dec], p. 327—381.

Cannon, J. L., 1966, Outcrop examination and interpretation of
paleocurrent patterns of the Blackleaf Formation near Great
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graphic traps, Sweetgrass arch—Billings Geol. Soc., 17th Ann.
Field Conf. 1966, Guidebook: p. 71—111.

Clark, F. R., 1923, Notes on the Kevin-Sunburst oil field, Montana:
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Cobban, W. A., 1950, Telegraph Creek formation of Sweetgrass arch,
north-central Montana: Am. Assoc. Petroleum Geologists Bull.,

- v. 34, no. 9, p. 1899—1900.

1951a, Colorado shale of central and northwestern Montana

and equivalent rocks of Black Hills: Am. Assoc. Petroleum

' Geologists Bull., v. 35, no. 10, p. 2170—2198.

1951b, Scaphitoid cephalopods of the Colorado group: U.S.

Geol. Survey Prof. Paper 239, 42 p., 21 pls. [1952].

1955a, Cretaceous rocks of northwestern Montana, in Billings

Geol. Soc. Guidebook 6th Ann. Field Conf., Sweetgrass arch—

 

 

 

62

Disturbed belt, Montana, 1955: p. 107—119.

1955b, Some guide fossils from the Colorado shale and Tele-

graph Creek formation, northwestern Montana, in Billings

Geol. Soc. Guidebook 6th Ann. Field Conf., Sweetgrass arch—

Disturbed belt, Montana, 1955: p. 198—207, pls. 1—4.

1956, Cretaceous rocks along part of southeast boundary of
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Cobban, W. A., Erdmann, C. E., Alto, B. R., and Clark, C. H., 1958,
Scaphites depressus zone (Cretaceous) in northwestern Mon-
tana: Am. Assoc. Petroleum Geologists Bull., v. 42, no. 3, p.
656L660.

Cobban, W. A., Erdmann, C.‘E., Lemke, R. W., and Maughan, E. K.,
1959, Revision of Colorado group on Sweetgrass arch, Montana:
Am. Assoc. Petroleum Geologists Bull., V. 43, no. 12,
p. 2786—2796.

Cobban, W. A., Rohrer, W. L., and Erdmann, C. E., 1956, Discovery
of the Carlile (Turonian) ammonite Collignoniceras woollgari
in northwestern Montana: Jour. Paleontology, V. 30, no. 5,
p. 1269—1272.

Cockerell, T. D. A., 1919, Some American Cretaceous fish scales;
with notes on the classification and distribution of Cretaceous
fishes [preface by T. W. Stanton]: U.S. Geol. Survey Prof. Paper
12(LI, p. 165—202, 7 pls.

Collier, A. J., 1929, The Kevin-Sunburst oil field and other pos-
sibilities of oil and gas in the Sweetgrass arch, Montana: U.S.
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Dobbin, C. E., and Erdmann, C. E., 1930, Map of the Great Falls—
Conrad region, Montana: U.S. Geol. Survey.

1955, Structure contour map of the Montana Plains: U.S.
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Douglas, R. J. W., 1952, Preliminary map, Waterton, Alberta:
Canada Geol. Survey Paper 52—10.

Edwards, R. G., 1960, Cretaceous Spinney Hill sand in west-central
Saskatchewan: Alberta Soc. Petroleum Geologists Jour., v. 8, no.
5, p. 141_153.

Erdmann, C. E., 1948, Geology of the Lothair area, Liberty County,
Montana: U.S. Geol. Survey Oil and Gas Inv. Prelim. Map 87.

Erdmann, C. E., and Davis, N. A., 1939, Geologic map of the Cut
Bank—West Kevin—Border districts, Glacier, Toole, and Pondera
Counties, Montana: U.S. Geol. Survey.

Erdmann, C. E., Gist, J. T., Nordquist, J. W., and Beer, G. W., 1947,
Map of the areal and structural geology of T. 35 N., R. 3 W.,
Toole County, Montana, showing oil pools in West Kevin dis-
trict, Kevin-Sunburst oil field: U.S. Geol. Survey.

Erdmann, C. E., and Schwabrow, J. R., 1941, Border—Red Coulee oil
field, Toole County, Montana, and Alberta, Canada, in Levorsen,
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Geologists [Dec], p. 267—326.

Fisher, C. A., 1907, The Great Falls coal field, Montana: U.S. Geol.
Survey Bull. 316—C, p. 161—173.

1909, Geology of the Great Falls coal field, Montana: U.S.
Geol. Survey Bull. 356, 85 p.

Fox, R. D., 1966, Geology and ground-water resources of the
Cascade—Ulm area, Montana: Montana Bur. Mines and Geology
Bull. 52, 64 p., illus.

Fox, R. D., and Groff, S. L., 1966, Stratigraphic and structural inves—

 

 

 

 

tigations of the Cascade-Ulm area, Montana, in Symposium,‘

Jurassic and Cretaceous stratigraphic traps, Sweetgrass
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Goddard, E. N., chm., and others, 1948, Rock-color chart: Natl. Re-
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Assoc. Petroleum Geologists Bull., v. 35, no. 11, p. 2427—2429.

‘

 

BLACKLEAF AND MARIAS RIVER FORMATION S, SWEETGRASS ARCH, MONTANA

Gwinn, V. E., 1961, Geology of the Drummond area, central—western
Montana: Montana Bur. Mines and Geology Spec. Pub. 21 (Geol.
Map 4).

Haas, Otto, 1949, Acanthoceratid Ammonoidea from near Greybull,
Wyoming: Am. Mus. Nat. History Bull., v. 93, art. 1, 39 p.,
15 pls.

Jeletzky, J. A., 1955, Belemnitella praecursor, probably from the
Niobrara of Kansas, and some stratigraphic implications: Jour.
Paleontology, v. 29, no. 5, p. 876—885.

Kerr, J. H., Pecora, W. T., Stewart, D. B., and Dixon, H. R., 1957,
Preliminary geologic map of the Shambo quadrangle, Bearpaw
Mountains, Montana: U.S. Geol. Survey Misc. Geol. Inv. Map
I—236, scale 1:31,680, with text.

Knechtel, M. M., 1959, Stratigraphy of the Little Rocky Mountains
and encircling foothills, Montana: U.S. Geol. Survey Bull.
1072—N, p. 72a752.

Koskinen, V. K., 1951, Marker Bed F in the Colorado shale, Kevin—
Sunburst dome area, Toole County, Montana: Washington State
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McLearn, F. H., 1929, Cretaceous invertebrates, in Mesozoic paleon—
tology of Blairmore region, Alberta: Canada Natl. Mus. Bull. 58,
p. 73—79, pls. 13—19.

Maughan, E. K., 1961, Geology of the Vaughn quadrangle, Montana:
U.S. Geol. Survey Geol. Quad. Map GQ—135.

Meek, F. B., and Hayden, F. V., 1861, Descriptions of new Lower
Silurian (Primordial), Jurassic, Cretaceous, and Tertiary fossils,
collected in Nebraska Territory‘l‘w, with some remarks on the
rocks from which they were obtained: Acad. Nat. Sci. Philadel-
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1862, Descriptions of new Cretaceous fossils from Nebraska
Territory' ' ' Acad. Nat. Sci. Philadelphia Proc. 1862, p. 21—28.

Mudge, M. R., 1965, Bedrock geologic map of the Sawtooth Ridge
quadrangle, Teton and Lewis and Clark Counties, Montana:
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1972, Pre—Quaternary rocks in the Sun River Canyon area,
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of Sweetgrass arch: Montana Bur. Mines and Geology Mem. 1,
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Powers, Sidney, and Shimer, H. W., 1914, Notes on the geology ofthe
Sun River district, Montana: Jour. Geology, v. 22, p. 556—559.

Reeside, J. B., Jr., and Cobban, W. A., 1960, Studies of the Mowry
shale (Cretaceous) and contemporary formations in the United
States and Canada: U.S. Geol. Survey Prof. Paper 355, 126 p.

Reeves, Frank, 1929, Thrust faulting and oil possibilities in the
plains adjacent to the Highwood Mountains, Montana: U.S.
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Romine, T. B., 1929, Oil fields and structure of Sweetgrass arch,
Montana: Am. Assoc. Petroleum Geologists Bull., v. 13, no. 7, p.
779~797.

Russell, L. S., and Landes, R. W., 1940, Geology of the southern
Alberta Plains: Canada Geol. Survey Mem. 221, Pub. 2453,
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Schmidt, R. G., 1963, Preliminary geologic map and sections of the
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1966, Preliminary geologic map ofthe Comb Rock quadrangle,
Lewis and Clark County, Montana: U.S. Geol. Survey Misc.
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Alberta, in Alberta Soc. Petroleum Geologists Guidebook 6th
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von Nordwestdeutschland; II, Teil; Biometrie, Dimorphismus

 

 

 

 

REFERENCES CITED 63

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1918, Oil and gas geology of the Birch Creek—Sun River area,

 

 

 

 

northwestern Montana: US. Geol. Survey Bull. 691, p. 149—184.

Stelck, C. R., 1958, Stratigraphic position of the Viking sand: A1-
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Webb, J. B., and Hertlein, L. G., 1934, Zones in Alberta shale (“Ben-
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Weed, W. H., 1899, Description of the Fort Benton quadrangle [Mon-
tana]: U.S. Geol. Survey Geol. Atlas, Folio 55, 9 p.

Willis, Bailey, 1902, Stratigraphy and structure, Lewis and
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Zeller, R. A., Jr., and Read, C. B., 1956, Occurrence of Tempskya
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[abs]: Geol. Soc. America Bull., v. 67, no. 12, pt. 2, p. 1804.

 

 

 

 

 

 

 

  
 
  
    
   
 

Page
A
Acknowledgments _____________________________ 2
Antelope Coulee ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 44
Arrow Creek Member ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 33
B

Badger Creek ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 9
Bearpaw Mountains ,,,,,,,,,,,,,,,,,,,,,, 15, 16, 52
Bears Den district H, 37
Bears Den oil field ________________________ ._- 50
Belle Fourche Shale ,,,,,,,,,,,,,,,,,,,,,,,,,, 37, 39
Belt Butte ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4, 26, 34
Belt Creek ________________________________ 7
Benton Lake ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, H- 37
Benton Shale ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 3, 4, 37
Bighorn Basin __________________________________ 55
Bighorn Formation ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 46
Birch Creek _____ __ 4, 5, 10, 16,37, 40, 44
Bird Creek ,_ W, 27
Black Coulee e." 39
Black Hills ,,,,,,,,, _ 5, 19, 37, 39, 44,47, 50
Blackhorse Lake Flat _____ 26, 27, 32
Blackleaf Creek ______ , 5
Blackleaf Formation 1,. W 2, 5
Blackleaf Sandy Member , 4
Bluesky Formation __ H, 16
Bootlegger Member _____ 2, 5, 31
Border—Red Coulee oil field 1. 9, 16
Brady oil field ,,,,,,,,,,,,,,, _ 27, 46
Bridge Creek Limestone Member ,,,,,,,,,, ___ 42

C

Cardium Formation.
Carlile Formation
Carlile Shale ,
Carter Ferry w-
Chalk Butte nose _
Chert pebbles
Cody Shale"
Colorado Formatiom
Colorado Group _

 
 
 
  
  
 
 
  

   

 

  
   
   
 

 

Colorado Shale ,,,,,,,,,,,,,,,,

Cone Calcareous Member ,,,,,,,,,,,,,,,,,,,,,, 5, 40
Cone Member ,,,,,,,,,,,,,,,,,,,,,,,, 2, 5, 37, 40, 46
Cone triangulation station ,,,,,,,,,,,,,,,,,,,, 37, 40
Crowsnest River ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 46
Cut Bank oil and gas field ,,,,,,,,,,,,,, 9, 27, 37, 50
Cyprian Sandstone Member ,,,,,,,,,,,,,,,,,,,,,, 19

D, E
Dakota Formation 4
Dearborn River. ,, ,,,,,,,,,, n, 5
Disturbed belt 1 4, 5, 9, 16, 27, 37, 45, 46, 50, 52
Eagle Formation ,,,,,,,,,,,,,, "a _..__ 4, 55
F

Fairport Chalky Shale Member ,,,,,,,,,,,,,,,,,, 42
Fall River Formation ,,,,,,,,,,,,,,,,,,,,,,,,,,, 11
Ferdig Member .1" ,,,,,,,,,,,,,, 2, 5, 44
First Cat Creek sand _ ,,,, 11
Flood Member q“ ,,,,,, 2, 5, 6, 9,11,16
Floweree Member W 2, 5, 33,37
Fort Benton Group, Formation No. 2- H, 2
Fort St. John Group ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 16

 

INDEX

[Italic page numbers indicate major references]

 

 

 

 
 

 

 

 

 

 

 

 

 

   

Page

Fort Hays Limestone Member ,,,,,,,,,,,,,,,,,,,, 50

Fossils:

Actinocamax sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 59, 60

Ammonites ,,,,,,,,,,,,,,,,,,,,,, 34, 39, 47, 53, 55

Ammonites mulani _____ 2
percarinatus _______ 2
vespertinus ,,,,,,,,, 2

Anchura quitmanensis
sp

Anemia fremonti _______

Anemia ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 10, 19, 40
Subquadrala , a,

Araucariouxylon sp _____

Baculites asper ,,,,,,,,,,,,,,,,,,,,,,,, 56, 57, 58, 59
besairlei ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 49
codyensis ,,,,,,,,,,,,,,,,,,,,,,,,,, 56, 57, 58
haresi ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 55
mariasensis ,,,,,,,,,,,,,,,,,,,,,,,,,, 53, 60, 61
sweetgrassensis ,,,,,,,,,,,,,,,,,,,,,,,,,, 53, 61
thomi ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 55, 56
yokoyamai ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 47
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 48, 55, 57, 59

Brachiopods __________________________ 18, 19, 21, 32

Callista sp ________________________________ ,___ 40

Callistina belviderensis __________________________ 19

Calycoceras canitaurinum ____________________ 39, 40

Cardium kansasense ____________________________ 19
pauperculum ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 46

Clioscaphites chateauensis ____________________ 52, 55
montanensis ,,,,,,,,,,,,,,,,,,,,,,,,,, 53, 56, 57
nauimexicanus ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5, 56
uermiformis
sp _______________________________ 57

Coccoliths _____________________

Cmyatoceras nebrascense ,,,,,,,

Collingnoniceras regulare ,,,,,,,,,,,,,,,,,,,, 47, 50
woollgari ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 42, 47, 50
sp ___________________

Cyrena dakotensis

Desmoscaphites erdmanni ____________________ 55, 56

Dinosaur bones ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 18

Drepanochilus ruida ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 43
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 61

Dryandroides sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 28

Dunueganocerus albertense ______________________ 39

Erythrinalepis mowriensis ________________________ 34

Fish bones ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 21, 33, 34

Foraminifera ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 41, 43

Gastropods ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 7, 18

Holcalepis lransuersus ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 34

Ichthyodecles sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 44, 50

Inaceramus anglicus , _ _ _
bellvuensls ,,,,,,,,,,,

 

caddottensis _ V _ s 1.. ..
comancheanus _ . , _

 

 

 

 

 

 

 

cordiformis ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 57
corpulentus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 60
deformls ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, __ 53, 61
erectus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 53
fragilis ,,,,,,,,,,,,,,,,,,,,,,,,, 2, 48, 49, 50
labiatus 4
[Mytilaides] ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 41
latus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2
lundbreckensis ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 56
mesabiensls ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 39
patootensiformis
problematicus 2
stantoni ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 53, 58

 

 

 

Page
lnoceramus —Continued
tenuirostratus 2
(Cordiceramus) cordiformis ,,,,,,,
(Sphenoceramus) lundbreckensis ,,,,,,,,,,,,,, 55
(Volviceramus) inuolutus ,,,,,,,,,,,,,,,,,, 53, 59
undabundus ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 59

sp 19, 24,40, 43, 44,47, 48, 49,56, 57, 58, 59, 60, 61
Leuel'ehthyops vagans ,
Lingula ,,,,,,,,,,,,,,,

 

 

subspalulata ____________________________ 18, 19
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4, 21, 29, 36
Lucina ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

   
 
 

Mantelliceras canitaurinum ,,,,,,,,,,,
Martesia sp
Membranipora sp ,,,,,,,,,,,,,,
Metaicoceras masbyense ,,,,,,,

muelleri ,,,,,,,,,,,,,,,,,
Mollusks ,,,,,,
Mytiloides ,,,,,

labiatus ________________________________ 42, 43

mytiloides ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 42, 43, 44
Nautilus elegans ,,,,,,,
Nelumbites sp _________
Neogastroplites ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 28, 34
N ucula

 

 

   

 
 

 

 

   
 

N uculana

sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 57
Nymphalucina subundata ________________________ 43

sp __________________________________________ 44
Ophiomorpha ____________________________________ 10
Ostrea anomioides ______________________________

congesta _________________________

larimerensis

sp ,-_ 43, 55,60
Oysters ,,,,,,,,,,,,,

 

 
  
  

 

 

 

 

  
 
  
  
 
 
 
 
 
  
 

Oxytoma sp

Pecten syncyclomema sp ,,,,,,

Pelecypods ________________________________ 5, 19, 46

Phelopteria gastrodes ____________________________ 43
salinaensis _________________________________ 19
sp _________________________________________ 19

Phaladomya papyracea ,,,,,,,,,,,,,,,,,,,,,,,, 2, 61

Plans sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, , 28

Prionacyclus hyatti ,,,,,,,,,,,,,,,,, , 47
wyomingensis wyomingensis _ 47
sp ______________________ , 47

Protelliptio douglassi H" , 9

Pseudomelania hendricksoni ,1 _ 56

Pseudoperna cangesta ,,,,,,,,,,,,,,,,,,,, 56, 59, 60

Pteroscaphites auriculatus __________________

Reesidella montanaensis ,,,,,,,

Rhabdospheres _ ,,,,,,,,,,,,,,,

Scaphites artllobus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 53
bighornensis __________ 47
binneyi ,,,,,,,, 53
carlilensis ___. 47,49
coruensis_,,,,,,,,,,,,,,, _ 47
delicatulus ,,,,,,,,,,,,,, _ 43
depressus _ ,
ferronensis W - 47
gracillistriams . , 53
larvaeformis , _ 2

leei ______
mariasensis
meeki _ A _

 

nigricallensts
pendicostatus ,,,,,
pisinnus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 48

65

66

 

 

 

 

   
   
 
 
     

 

Page
Scaphites —Continued
preventricosus ,,,,,,,,,,,,,,,,,,,,,,,,, 53, 60, 61
stantoni ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 58
sweelgrassensis ,,,,,,,,,,,,,,,,,,,,,,,,, 53, 61
tetonensis ,,,,,,,,,,,,, 53
ventricosus ________________________ 2, 53, 59
uermiformis ,,,,,,,,,,,,,,,,,,,,,,,,, 2, 55, 56, 57
warreni ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2, 47
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 47, 49, 58, 60
Sciponoceras gracile ,,,,,,,,,,,,,,,,,,,,,,, 42, 43, 44
Shark tooth ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 19, 23
Spondylus sp H, W ,,,,,,,,,,,,,,,,,,,,,,,,,, 59
Stantonogyra silberlingi ,,,,,,,,,,,,,,,,,,,,,,,,,, 9
Tempskya grandis ,,,,,,,,,,,,,,,,
knowltoni ,1, ,,,,,,,,,,,,,,,,,,,,,,,,,, 28
Tessarolax hitzii , ,,,,,,,,,,,,,,,,,,, 61
Trigonia sp 1.. ,,,,,,,,,,,,,, 19
U nio farri ,,,,, 9
reesideanus 9
Unios ,,,,,,,,,,,,,,,,,,,, 18
Veniella goniophora ,,,,,,, 53, 61
mortoni ,,,,,,,,,,,, 2
Venilia mortoni ,,,,,,,,,, 2
Watinoceras coloradoense , __ 43
reesidei ,,,,,,,,,,,,,,,,,, __ . H W 42, 43
worm burrows ,,,,,,,, 8, 10, 14, 17, 19, 23, 24, 39, 43
G, H
Glacier National Park ,u. 4, 7, 16, 27, 37, 40, 45, 51
Gore Hill ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 6, 8
Greenhorn Formation ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 39
Greenhorn Limestone ,,,,,,,,,,,,,,,,,,,,,,,, 40, 42
Highwood Creek ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 32
Highwood Mountains ,,,,,,,,,,,,,,,,,,,, 16, 40, 41
Historical summary ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2
l, J, K
Introduction ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2

Joli Fou Formation 1 ,,

 

 

 

INDEX
Joli Fou Shale ,,,,,,,,,,,,,, ‘
Kevin Member __________________________ 2, 46, 50
Kevin Shale Member ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5

Kevin-Sunburst dome
5, 27, 32, 33, 36,37, 40, 44, 46, 50,52, 53

  

   

 

Kiowa Shale _________________________________ 10, 19
Kootenai Formation _________________ 4, 6, 7, 10, 13, 14
L
Lake Creek ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 45
M
MacGowan Concretionary Bed ,,,,,,,,,,,,,,,, 52, 53
Madison Limestone _______________________________ 46
Mannville Formation ____________________________ 16
Marias River Shale ,,,,,,,,,,,,,,,,,,,,,,,, 2, 5, 36
Missouri River ,,,,,,,,,,,,,,,,,,,,,,,, 6, 16, 27, 32
Montana Group ________________________________ 4
Mosby Sandstone Member ,,,,,,,,,,,,,,, 37, 39, 40
Mowry Shale _____________________ 28, 31, 34, 37, 41
Muddy Creek ______________ 16, 27, 32, 33, 37, 40, 45

N
Newcastle Sandstone ,,,,,,,,,
Newman Spring ,,,,,,
Niobrara Division, Formation Not 3 ,,,,,,,,,,,,,, 3
Niobrara Formation ,,,,,,,,,,,,,,,,,,,,,,,, 5, 50, 52
Niobrara River ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 3
P
Phosphatic pebbles ,,,,,,,,,,,,,,,,,,,,,,,, 51, 53, 55
Pincher Creek gas field ,,,,,,,,,,,,,,, 46
Pondera oil field ________________ 10, 15, 27, 37, 44, 50
R
Raglan Butte ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

 

References cited

 

 

 

 

 

Page
S

St, Mary River ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 9
Sage Breaks Member ____________________________ 47
San Juan Basin _________________________________ 47
Second Whitlash sand ____________________________ 16
Skull Creek _____________________ 28
Skull Creek Shale _______________________ 10, 16, 19
Smith River ____________________________________ 7
Smoky Hill Chalk Member ,,,,,,,,,,,,,,,, 50, 53, 55
South arch ,,,,,,,,,,,,,, 6, 15, 16, 33, 36, 37, 44, 46
South Platte Formation ,,,,,,,,,,,,,,,,,,,,,,,,,, 10
Spinney Hill Member ________________________ 16, 19
Stebinger, Eugene, quoted 111111111111111111111111 5

Sun River 4,5,6, 8, 9, 15, 16, 27, 32,37, 40, 45, 46, 50
Sweetgrass arch ,, 2, 4, 6,9, 15,27, 33, 36, 40, 50, 52

 

   

Sweetgrass Hills ,,,,,,,,,,,,,,,,,, 16, 27, 37, 44, 50
T

Taft Hill Glauconitic Member ____________________ 5

Taft Hill ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27, 32

Taft Hill Member ,,,,,,,,,,,,,,,,,, 2, 13, 15, 30, 31

Telegraph Creek Formation ,,,,,,,,,,,,,,,, 4, 52, 55

Thermopolis Shale ,,,,,,,,,,,,,,,

Turner Sandy Member ___________

Two Medicine Creek ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 52
V

Vaughn Bentonitic Member ,,,,,,,,,,,,,,,,,,, 5, 25

Vaughn Member _____________________ 2, 16, 25, 33

Viking Sandstone ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 20

Virgelle Sandstone Member ,,,,,,,,,,,,,,,,,,,,,, 4
W

West Utopia oil and gas field ,,,,,,,,,,,,,, 37, 44, 50

Whitlash dome ,,,,,,,,,,,,,,,,

Williston basin _____________ .__

Willow Creek ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 41

WolfCreek ”Hun.” v. .. 7,26, 27, 38, 45, 46, 50

 

 

 

mwnwyfiw” J,

 

Q75

  
  

svv
I? ‘DA
Se;
v5? 6'

MARY OF
IFICANT

GEOLOGICAL SURVEY

ral resources
-r resources
eering geology

.ii‘l’SZLlii’y RESEARCH l 975

blic lands
. information
d analysis
sfigations in
her countries

S OF—

sfigafions in
rogress
perating agencies

logical Survey

 

 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 975

GEOLOGICAL SURVEY
RESEARCH I975

 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 975

A summary of recent significant scientific
and economic results accompanied by a

list of geologic and hydrologic investigations
in progress and a report on the status of
topographic mapping

 

 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON, DC: I975

UNITED STATES DEPARTMENT OF THE INTERIOR

THOMAS S. KLEPPE, Secretary

GEOLOGICAL SURVEY

V. E. McKelvey, Director

Library of Congress catalog-card No. 68-46150

 

For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, DC. 20402
Stock Number 024-001-027747

FOREWORD

“Geological Survey Research 1975” is the 16th annual synopsis of the
results of U.S. Geological Survey investigations.These studies are largely
directed toward the development of knowledge that will assist the Nation
to use and conserve the land and its physical resources wisely. They are
wide ranging in scope and deal with almost every facet of solid-earth sci-
ence and fact finding.

Many of the studies reported here are continuations of investigations
that have been in progress for several years or more. But others reflect
the increased attention being given to problems that have assumed greater
importance in recent years—problems relating to mineral fuels and min-
eral resources, water quality, environmental impact of mineral resources,
land-use analysis, earthquake hazards reduction, subsidence, and the ap-
plications of LANDSAT data, to cite a few examples.

These changes in program emphasis are paralleled by new develop-
ments in earth science and technology, and the two combine, as they have
throughout the Survey’s history, to keep these investigations dynamic in
their character and direction.

0- €. \Iwe ((vfi‘j/

vey,
Director.

III

 

CONTENTS

Foreword

Abbreviations and metric-English equivalents _______

Mineral-resource and mineral-fuels investigations ___-
Geology of mineral occurrences ________________
Geologic studies in potentially mineralized areas-

Areal mineral appraisal __________________
Mineral investigations related to the Wilder-
ness Act ___________________________
Primitive areas ______________________
Wilderness areas _____________________
Study areas _________________________
Mineral commodity appraisal ______________
Office of Minerals Exploration ____________
Minerals Discovery Loan Program _____
Mineral-resource exploration technology _________
Resource analysis ____________________________
Coal resources _______________________________
Oil and gas resources _________________________
Oil-shale resources ___________________________
Nuclear-fuels resources _______________________
Geothermal resources _________________________

Regional geologic investigations ___________________
New England ——-—--—--.— ______________________
Structural and stratigraphic studies _______
Quaternary geology ______________________
Appalachian Highlands and the Coastal Plains _-
Central region and Great Plains _______________
Kentucky ________________________________
Michigan and Wisconsin __________________
Minnesota _______________________________
Nebraska and Kansas _____________________
Rocky Mountains _____________________________
Stratigraphic studies _____________________
Igneous studies ___________________________
Structural and geophysical studies _________
Geothermal resource studies ______________
Basin and Range Province ____________________
Stratigraphic and structural studies _______
Geochemical and geochronological studies ___
Pacific coast region ___________________________
California _______________________________
Oregon __________________________________
Washington ______________________________
Alaska ______________________________________
General __________________________________
Northern Alaska _________________________
West-central Alaska ______________________
East-central Alaska ______________________
Southern Alaska _________________________
Southwestern Alaska _____________________
Southeastern Alaska ______________________
Puerto Rico __________________________________

 

Regional geologic investigations—Continued

Geologic maps _______________________________
Large-scale geologic maps ________________
Intermediate-scale geologic maps ___________
Maps of large regions ____________________
Water-resource investigations
Northeastern region __________________________
Connecticut
Indiana ___________; ______________________
Maryland _____ F __________________________
Massachusetts ____________________________
Michigan _________________________________
Minnesota
New Jersey ______________________________
New York _______________________________
Pennsylvania
Virginia _________________________________
West Virginia ____________________________
Southeastern region __________________________
Alabama
Florida __________________________________
Georgia
Kentucky ________________________________
North Carolina ___________________________
Puerto Rico ______________________________
South Carolina ___________________________
Tennessee
Central region ________________________________
Arkansas
Colorado _________________________________
Kansas '-_________; _______________________
Louisiana ________________________________
Montana
Nebraska ________________________________
New Mexico _____________________________
North Dakota ____________________________
Oklahoma ________________________________
South Dakota ____________________________
Texas
Utah
Wyoming ________________________________
Western region _______________________________
Multistate studies ____________; ___________
Alaska
Arizona

Oregon __________________________________

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VI CONTENTS

Page
Waters-resource investigations—Continued
Special water-resource programs _______________ 115
Saline water _____________________________ 115
Data coordination, acquisition, and storage ____ 116
Office of Water-Data Coordination _____ 116
Water-Data Storage System ___________ 117
Urban water program ____________________ 118
Urban. water-resource studies _________ 118
Urban runoff and floods ______________ 119
Quality of storm runoff in urban areas __ 120
Hydrologic effects of waste disposal in
urban areas ____________________ 120
Water use _______________________________ 121
Coordinate water-quality programs ________ 122
International Hydrological Decade, 1965—1974 123
Marine geology and coastal hydrology investigations- 125
Marine and coastal geology ___________________ 125
Atlantic continental margin _______________ 125
Shelf geophysical, structural, and resource
studies ______________________ - 125
Shelf environmental studies ___________ 125
Gulf of Mexico and Caribbean continental
margin _____________________________ 126
Geophysical, structural, and resource
studies ________________________ 126
Coastal environmental studies _________ 127
Pacific continental margin _________________ 127
Geophysical, structural, and resource
studies ________________________ 127
Coastal environmental studies _________ 128
Arctic-Alaska continental margin __________ 129
Geophysical, structural, and resource
studies ________________________ 130
Coastal environmental studies _________ 130
Shelf environmental studies ____________ 130
General oceanic and international studies ___ 132
Estuarine and coastal hydrology _______________ 134
Atlantic coast ____________________________ 134
Gulf coast _______________________________ 1 135
Pacific coast _____________________________ 135
Management of natural resources on Federal and
Indian lands _______________________________ 137
Classification and evaluation of mineral lands __- 137
Waterpower classification—preservation of reser-
voir sites ______________________________ 138
Supervision of mineral leasing _________________ 138
Cooperation with other Federal agencies _______ 138
Geologic and hydrologic principles, processes, and tech-
niques _____________________________________ 140
Experimental geophysics ______________________ 140
Heat flow _______________________________ 140
Rock magnetism __________________________ 141
Computer modeling _______________________ 142
Geomagnetism ___________________________ 143
Applied geophysics techniques _________________ 145
Geochemistry, mineralogy, and petrology ________ 147
Experimental and theoretical geochemistry __ 147
Mineral studies and crystal chemistry _____ 149
Crystal chemistry of the silicates ______ 149
~ Mineralogic studies ___________________ 149
Volcanic rocks and processes _______________ 149
Hawaiian volcano studies _____________ 149

 

Geologic and hydrologic principles, processes, and
techniques—Continued
Geochemistry, mineralogy, and petrology—Continued
Volcanic rocks and processes—Continued
Columbia plateau studies _____________
Caldera studies
Petrologic and petrochemical studies _-_
Plutonic rocks and magmatic processes _____
Metamorphic rocks and processes __________
Geochemistry of water and sediments ______
Statistical geochemistry and petrology _____
Isotope and nuclear geochemistry _____________
Isotope tracer studies ____________________
Stable isotopes ___________________________
Advances in geochcronometry ______________
Geothermal systems __________________________
Sedimentology _______________________________
Variability of sediment yields _____________
Sediment transport and deposition _________
Channel scour ____________________________
Aerial photography ______________________
Glaciology ___________________________________
Paleontology _________________________________
Paleozoic of the United States ____________
Mesozoic of the United States ______________
Cenozoic of the United States ______________
Other paleontologic studies ________________
Ground-water hydrology ______________________
Surface-water hydrology ______________________
Chemical, physical, and biological characteristics
of water _______________________________
Relation between surface water and ground water
Soil moisture ________________________________
Evapotranspiration ___________________________
Limnology and potamology ____________________
Plant ecology ________________________________
New hydrologic instruments and techniques _____
Computer programs for modeling and solving
hydrologic problems __________________
Sea-ice studies _______________________________
Analytical chemistry _________________________
Isotope dilution __________________________
Activation analysis _______________________
Emission spectroscopy ____________________
Analysis of water ____________________________
Geology and hydrology applied to the public welfare"
Earthquake studies ___________________________
Geophysical studies _______________________
Geologic studies _________________________
Engineering geology __________________________
Studies related to land use and environment _____
Urban geologic studies ____________________
Environmental geology of cities and counties
Coastal environmental geology _____________
Volcano hazards __________________________
Environmental problems resulting from
mining _____________________________
Investigations related to nuclear energy ________
Underground nuclear explosions ____________
Relation of radioactive wastes to the
hydrolbgic environment ______________
Sites for nuclear-power reactors and other
facilities

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214

CONTENTS
Page
Geology and hydrology applied to the public welfare Topographic surveys and mapping _________________
—Continued National‘mapping program ____________________
Floods ______________________________________ 216 Mapping coordination and requirements ________
Outstanding floods _______________________ 217 National Cartographic Information Center ______
Flood-frequency studies ___________________ 217 Mapping accomplishments ————————————————————
Flood mapping ___________________________ 219 National Atlas _______________________________
Water quality and contamination ______________ 220‘ Programs in Antarctica ———————————————————————
Environmental geochemistry ___________________ 224 International (”Operation ——————————————————————
Land subsidence ______________________________ 225 Research and development ___________ , ________
Astrogeology _____________________________________ 228 Field surveys ————————————————————————————
Planetary studies _____________________________ 22s Photogrammetl'y -------------------------
Lunar investigations __________________________ 229 03145031“th —————————————————————————————
Terrestrial analogs and experimental studies ___ 231 Computer technology _____________________________
Crater investigations _____________________ 231 Reston computer system ______________________
Mineralogical investigations _______________ 233 Time-sharing systems _________________________
Lunar sample investigations __________________ 233 Data communications _________________________
Remote sensing and advanced techniques ____________\ 237 Data-base management system ________________
Earth Resources Observation Systems (EROS) New software support ________________________
program _______________________________ 237 New facilities ________________________________
Western region ——————————————————————————— 238 US. Geological Survey publications _________________
Central region ——————————————————————————— 239 Publications program _________________________
Eastern region ——————————————————————————— 240 Publications issued ___________________________
Foreign areas ——————————————————————————— 240 How to obtain publications ____________________
Remote-sensing experiments by other Bureaus 242 Over the counter _________________________
luminescence studies _____________________ 242 By mail ________________________________
:pplicatlons to geologic studies --------------- 243 References cited __________________________________
Aggllzztlzgz 1:) giggithlzugtiliies—::::::: 31,51 Cooperators and other financial contributors during
Applications to geographic studies _____________ 249 fiscal year 1975 """"""""""""""""
Land use and environmental impact ________________ 252 Federal cooperators ---------------------
Resource and Land Investigations program ______ 252 State, county, and local cooperators ____________
Council of State Governments Task Force ___ 252 Other c00perators and contributors ————————————
PTOdUCt evaluation project ________________ 252 US. Geological Survey offices ______________________
Environmental assessment with application to Headquarters ofl‘ices __________________________
Western coal development ___________ 253 Principal field offices __________________________
Land'Use Data a:‘nd Aniflym ngmm and 0th.” Selected field offices in the United States and
geographic stud1es ______________________ 253 P -
- . . uerto R1co ____________________________
Env1ronmental impact studies __________________ 256 . . .
Analysis of environmental impact statements 257 Computer'Center lesmn """""""""
Environmental impact research ____________ 257 Conservatlon Dmsxon. ____________________
International cooperation in the Earth sciences ______ 258 Regional ofiioes ——————————————————————
Technical assistance and cooperation ___________ 258 Area and dlStI‘ICt offices ———————————————
International commissions arid programs _______ 263 Earth Resources Observation Systems
Response to natural disasters _________________ 264 program ___________________________
Minerals attaché program ______________________ 264 Geologic Division ________________________
Summary by countries _______________________ 265 Regional Offices ______________________
Argentina _______________________________ 265 Offices _______________________________
Bollwa ______ _._ __________________________ 265 . . . . .
Brazil ___________________________________ 265 Publicatlon D1vrs10n ______________________
Colombia ________________________________ 266 Public Inquiries Offices _______________
Costa Rica ______________________________ 266 Distribution centers ___________________
Indonesia ________________________________ 266 Topographic Division _____________________
Kenya ___________________________________ 267 Water Resources Division _________________
Mexico __________________________________ 267 Regional offices ______________________
Nepal ___________________________________ 268 District offices _______________________
Oman ——————————————————————————————————— 268 Offices in other countries ______________________
Pakistan ————————————————————————————————— 268 Geologic Division _________________________
1;er d """""""""""""""""""" :23 Water Resources Division ________________
8:13;; A;;1—);_:::::::::::::::::::::: 269 Investigations in progress in the Geological Survey __
Thailand _________________________________ _ 271 Indexes __________________________________________
Yemen Arab Republic ____________________ 271 Subject index ________________________________
Antarctica ___________ \— _______________________ 2'72 Investigator index _____________________________

 

VII

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361
367

VIII

FIGURE

TABLE

2"

9‘

5”

95°98?

CONTENTS

ILLUSTRATIONS

Published geologic quadrangle maps of Kentucky as of May 1, 1975 _______________________________
Index map of the conterminous United States showing 1:250,000—sca1e geologic maps published as of De-
cember 31, 1974 ____________________________________________________________________________
Index map of Alaska, Hawaii, and Puerto Rico showing geologic maps published or on open file as of
December 31, 1974 _________________________________________________________________________
Index map of the conterminous United States showing areal subdivisions used in the discussions of
water resources ____________________________________________________________________________
Unit discharges of 7-d droughts of 10—yr duration in Mississippi tributaries below St. Paul, Minn., in re-
lation to drainage areas _____________________________________________________________________
Status of 1:24,000- and 1:62,500-scale mapping -_____-________' ____________________________________
Revision in progress, 1:24,000-sca1e topographic maps _____________________________________________
Revision of 1:250,000-scale topographic maps _____________________________________________________
Status of State base maps ______________________________________________________________________
Status of publication of 1:1,000,000-scale topographic maps. Work in progress is being done by the
USGS ____________________________________________________________________________________

TABLES

Concentrations of selected elements in a whole-rock sample and its leachate, Pando area, Eagle County,
, Colorado __________________________________________________________________________________
Mineral production, value, and royalty for fiscal year 1975 ______________________________________
Technical assistance to other countries provided by the USGS during fiscal year 1975 _______________
Technical and administrative documents issued in calendar year 1974 as a result of USGS technical and

scientific cooperative programs _______________________________________________________________

Page

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7:;
80

86
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278
279
280

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138
260

  

 

 

ABBREVIATIONS

  

 
   

  

a-c ______________________ alternating current f-l- ____________________________ focal length
AEC ______ Atomic Energy Commission (now a __________________________________ gravity
Nuclear Regulatory Com- GOES "Geostationary Operational Environ-
mission) mental Satellite
AID "Agency for International Development. GRASP _____ Geologic Retrieval and Storage
U.S. Department of State Program
AIDJEX ________ Arctic Ice Dynamics Joint h ______________________________________ hom-
Experiment HFU __________________________ heat-flow unit
atm ............................. atmosphere hp ....................... horsepower
_______ barrel HUD ___----Housing and Urban Development
Hz _________________ hertz (cycle per second)
IGC ___ _International Geological Congress
IGU ______ International Geographical Union
____________________ calorie IGY ___ ___--International Geophysical Year
CCT ______________ computer-compatible tape IHD -- --International Hydrological Decade
Ci ____________________________________ curie IHP -_ "International Hydrologic Program
CIPW __________ Cross, Iddings. Pirsson, and IUGS ______ International Union of Geological
Washington Sciences
CRIB “Computerized Resources Information J _____________________________________ jouie
Bank , JOIDES ____Joint Oceanographic Institutions
CRT ___- ____________ cathode ray tube Deep Earth Sampling
:1 ___- _______________________ day JTU ________________ JBCRson turbidity unit
dc ________________ mean diurnal temperature __________________ kelvin
d-c ___________________________ direct current __kilocalorie
DCP _Data Collection Platform KREEP ______ potassium, rare-earth elements,
DCS _________________ Data Collection System phosphorus
D0 ________________________ dissolved oxygen LANDSAT -.Land Satellite (formerly ERTS)
____Department of Defense lat __________________________________ latitude
DSDP _____________ Deep Sea Drilling Project loc. __ ____location
dy“ ------------------------ :__dyn-e long ............................... longitude
emu __ _______________ electromagnetic unit mb _________________________ millibar
EPA __ ___Environmental Protection Agency M V """"
ERDA ____Energy Resource and Development e """""""""""" megaelectronvolt
Administration ms/l ............ milligram per litre. or ppm
EREP -Earth Resources Experiment Package mGal ------------------------------- milligal
EROS “Earth Resources Observation Systems min _________________________________ minute
ERS ________________ Earth Resources Survey mo __________________________________ month

 

 

 

 

 

 
 
 
 
  

 

 

  
  

mol ___________________________________ mole
MSS ___________________ multispectral scanner
m.y. __ __________________ million years
II-z/E __________ microgram per gram, or ppm
ug/l ___________ microgram per litre, or ppb
ug/ml ._ _microgram per millilitre, or ppm
)1th _____________________________ micromho
NASA ______ National Aeronautics and Space
Administration
NAWDEX -_National Water Data Exchange
nm ______________________________ nanometres
NOAA ___National Oceanic and Atmospheric
Administration

NSF __________ National Science Foundation
ohm-m ___________________________ ohm-metre
Pa _________________________________ pascale
pI-I -_ _-_measure of hydrogen ion activity
ppb ________________________ part per billion
ppm ____part per million
ppt ___ ______________ part per thousand
RALI ______ Resource and Land Information
REE __ ________________ rare-earth element
rms _______________________ root mean square
s ____________________________________ second
SLAR -_ "side-looking airborne radar
SMOW __________ standard mean ocean water
TAPS _________ trans-Alaska pipeline system
TVA ___ ___Tennessee Valley Authority
U.N. ________________________ United Nations
UNESCO _______ United Nations Educational,

Scientific, and Cultural

Organization
USGS ________________ U.S. Geological Survey
USPHS __________ U.S. Public Health Service
UTM ________ Universal Transverse Mercator
V ___- _____________________________ volt
yr _____________________________________ year

METRIC-ENGLISH EQUIVALENTS

 

English equivalent

Length

0.03937 inch (in)
3.28 feet (ft)

Metric unit

millimetre (mm)
metre (m)

 

 

kilometre (km) .62 mile (mi)
Area
square metre (m!) 10.76 square feet (ft?)

square kilometre (km‘-’) 386 square mile (mi’)

II H II

 

 

hectare (ha) 2:47 acres
Volume
cubic centimetre (cm?!) 0061 cubic inch (inn)

cubic inches

35.31 cubic feet (fta)
0.00081 acre-foot (acre-ft)
.7

litre (1)
cubic metre (m3)
cubic metre

II H II II II H II II H

cubic hectometre (hma) acre-feet
litre 2.113 pints (pt)
litre 1.06 quarts (qt)
litre 26 gallon (gal)

cubic metre :00026 million gallons (Mgal or
6

10 go)
barrels (bbl) (1 bb1=42 gal)

 

 

cubic metre : 6.290

Weight
gram (g) = 0.035 ounce. avoirdupois (oz uvdp)
gram = .0022 pound, nvoirdupois (lb avdp)
tonne (t) : 1.1 tons, short (2,000 lb)

tonne .98 ton, long (2,240 lb)

 

'fic combinations

([1
'5
O
a
.-

 

kilogram per square

centimetre (kg/cmi') = 0.96 atmosphere (atm)
kilogram per square

centimetre = .98 bur (0.9869 atm)
cubic metre per second

(ma/s) : 35.3 cubic feet per second (ft-Vs)

 

Metric unit

English equivalent

Specific combinations——Continued

litre per second (l/s)

cubic metre per second
per square kilometre
[(mB/svkm’]

metre per day (In/d)

metre per kilometre
(m/km)

kilometre per hour
(km/h)

metre per second (m/s)

metre squared per day
(mil/d)

cubic metre per second
(ma/S)

cubic metre per minute
(ms/min)

litre per second (l/s)

litre per second per
metre [(l/s)/m]

kilometre per hour
(km/h)

metre per second (m/s)

gram per cubic
centimetre (g/cms)

gram per square
centimetre (g/cm?)

gram per square

: .0353 cubic foot per second

: 91.47 cubic feet per second per
square mile [(fta/s)/mi*]
3.28 feet per day (hydraulic
conductivity) (ftZd)

5.28 feet per mile (ft/mi)

.9113 foot per second (ft/s)
3.28 feet per second

H

II Ii

= 10.764 feet squared per day (ftz/d)
(transmissivity)

= 22.826 million gallons per day
(Mga /d)

=264.2 gallons per minute (gal/min)

: 15.85 gallons per minute

= 4.83 gallons per minute per foot
[(gal/mln) m1

= .62 mile per hour (mi/h)

= 2.237 miles per hour

: 62.43 pounds per cubic foot (lb/ft“)

: 2,048 pounds per square foot (lb/ft”)

 

 

centimetre .0142 pound per square inch (lb/in’)
Temperature
degree Celsius (’C) = 1.8 degrees Fahrenheit ("1“)

degrees Celsius
(temperature)

= [ (1.8 X °C) + 32] degrees Fahrenheit

 

IX

 

GEOLOGICAL SURVEY RESEARCH 1975

MINERAL-RESOURCE AND MINERAL-FUELS INVESTIGATIONS

GEOLOGY 0F MINERAL OCCURRENCES

Metallogeny and global tectonic theory

P. W. Guild proposed that many apparent con-
flicts between theories of metallogeny such as those
based on- geosynclinal development, relationship to
median'massifs‘ and regions of “autonomous activi-
zation,” lineament control, and other factors can be
resolved by principals of global tectonics. Endogenic
mineral deposits can form in at least four plate en-
vironments: (1) at accreting plate margins (rift or
ocean rise, ophiolite-associated deposits), (2) over
subducting zones near converging margins (cordil-
leran, island-arc deposits), (3) above hot spots or
mantle plumes in the interior of plates (Mississippi
Valley and other types), or (4) in regions of conti-
nental‘reactivization that may result from upwelling
of material from the asthenosphere behind a sub-
ducting plate of oceanic lithosphere (Great Basin
and Rocky Mountain deposits of the general Lara-
mide type). Chemical elements in ores may be de-
rived from the mantle directly or by two-stage or
multistage processes; their provenance and mode of
concentration into mineral deposits differ in many
ways that can be accounted for by the models pro—
posed.
Geochemical anomalies near the Haile gold mine

Preliminary compilation of geochemical data from
small streams in the Haile mine area of Kershaw and
Lancaster Counties, S.C., was carried out by Henry
Bell III. The data obtained by semiquantitative spec»-
trographic analysis show that a large area low in
iron coincides with the southeast-trending contact
between coarse volcaniclastic rocks and overlying
argillite in the Carolina slate belt. The low-iron area
encloses smaller areas with anomalous tin in heavy-
mineral concentrates as well as in massive pyrite
bodies at the Haile mine. Gold-bearing alluvium in
the same area, however, seems to reflect a pre-

 

Triassic shear zone trending northwest between two
granite plutons.

Structural control of the Hamme tungsten deposit, North
Carolina

At the Hamme tungsten deposit, J. E. Gair
found that the principal mineralized veins strike
north-northeast, dip steeply southeast, are lenticular
and en echelon, and in places have warps and buck-
les that plunge steeply to the south. Lenticular veins
contain and are separated by seams of sericite
schist, which contain small drag folds that also
plunge to the south. The tungsten lodes generally
are elongated steeply downward to the south in the
plane of the vein system. Lodes, warps, buckles, and
drag folds plunge along approximately similar axes.
The flow of silica-rich solutions and the later min-
eralizing fluid therefore appears to have been chan-
neled along the principal axes of warping and drag
folding. Within the veins, huebnerite-sulfide—fluorite
mineralization may be scattered quite irregularly
but commonly is distributed along sheeting (con-
spicuous parting parallel to the vein walls) and
along schist seams that diverge from sheeting and
strike northward across the northeast-trending
veins. Sheeting and schist seams were principal
pathways for mineralizing fluids moving through
the quartz veins. Tungsten mineralization is con-
fined to a large westward bulge in the northwestern
part of the Hamme granodiorite-tonalite pluton. The
bulge may be a last stage of multiple intrusion,
representing a late magma phase.

Zoned ore bodies in the Cave-in-Rock district, Illinois

Underground mapping of bedded ore bodies in
the Cave-in-Rock district by D. M. Pinckney
showed that the minerals form tw0 sets of zones.
Fluorite is zoned relative to calcite, fluorite occupy-
ing the central position. Sphalerite is zoned relative
to barite, Sphalerite occupying the central position.

1

2 GEOLOGICAL SURVEY RESEARCH 1975

The two sets of zones, fluorite-calcite and sphalerite.
barite, overlap, but the boundary between minerals
of one set generally does not coincide with the
boundary between minerals of the other set. Char-
acteristically, the interior of an ore body consists of
fluorite and sphalerite.
Occurrences of zinc in Kansas

Library research by M. H. Miller found references
(Lee, 1940, p. 78) to two occurrences of sphalerite
in the Mississippian limestones of Kansas, which
are the main host rocks of the tri-state zinc district
deposits. The first occurrence is in a drill hole at a
depth of 1415.8 to 1417.3 m in probable Burlington
Limestone in sec. 16, T. '16 S., R. 28 W., Lane
County, central western Kansas. The second occur-
rence is in sec. 17, T. 33 S., R. 6 W., southwest of
Wichita, in Harper County, Kan., where sphalerite
occurs associated with chert (or jasperoid?) and
crystals of white calcite in the Cowley Formation
at a depth of 1347.8 to 1352.4 m. Such occurrences
may be related to deeply buried Mississippi Valley-
type ore deposits.

Geologic setting of the Mogollon mining district, New Mexico-
a reappraisal

Reappraisal of the geologic setting of the Mogol-
lon, N. Mex., mining district based on geologic map-
ping and geophysics by J. C. Ratté, G. P. Eaton,
D. L. Gaskill, and D. L. Peterson (1974) indicated
a significant potential for discovering additional ore
bodies of precious or base metalsvwithin or adjacent
to the district. The Mogollon district is astride the
topographic margin of the Bursum Caldera of Ter-
tiary age and lies mainly within the structural moat
between the caldera wall and a resurgent dome.

Recognition of the caldera setting of the district
leads to new interpretations and correlations of the
volcanic stratigraphy within the district and in
adjoining parts of the Gila Wilderness and Gila
Primitive Area. Most important, perhaps, has been
the discovery of the intrusive relationship of the
Fanney Rhyolite, both Within and beyond the” dis-
trict. At the eastern edge of the Mogollon 71/2-min
quadrangle, the Fanney Rhyolite intruded older
andesites and erupted through a vent to form a
thick layer of pyroclastic material that previously
was mapped as a younger unit. Within the district,
similar crosscutting contacts of the Fanney Rhyolite
previously attributed to either faulting or rough
pre—Fanney topography are now considered to be
intrusive contacts. These observations confirm the
speculations by earlier investigators about a rela-
tionship between the distribution of the Fanney
Rhyolite, the ring fracture zone of the Bursum Ca1-
dera, and mineralization in the Mogollon district.

 

In addition to the rhyolite intrusions, several small
intrusions of hornblendic, latitic, or dacitic rocks
have been discovered recently within this ring frac-
ture zone. Thus, the geologic setting seems to be
favorable for extensive intrusion at depth along the
ring fracture zone and particularly where the cal-
dera margin is intersected by regional northeastern
and northwestern fracture belts.

Gravity and magnetic anomalies are spatially as-

sociated with the Mogollon district, and a gravity
high over the district is part of an elongate high
that continues southeastward to the Silver City and
Santa Rita mining districts. In a preliminary inter-
pretation of this gravity anomaly, Eaton related it
to the probable presence of Paleozoic carbonate
rocks in the subsurface, which provide a density
contrast with the dominant volcanic surface rocks.
Calcite veins, as much as 20 m wide north of the
Mogollon district, provide additional support for
this interpretation. The mineral potential of the
Mogollon mining district, as well as of other parts of
the Bursum Caldera ring fracture zone, is enhanced
by the possibility of extensive intrusion at depth
along the zone and the probabilityof a Paleozoic
carbonate section at depth adjacent; to the area of
intense volcanic eruptions and caldera subsidence.
Zeolite in southwestern New Mexico

Several extensive areas of rhyolitic tuif in the
Winston, N. Mex., area were mapped by C. H. Max-
well. The tuff has been altered over large areas to
material identified by R. A. Sheppard as being com-
posed largely of clinoptilolite and having a good
economic potential for industrial use. Resources may
be of the order of 45 million tonnes.
Four auriferous gravel units in the Hillsboro Las Animas

district, Sierra County, New Mexico

The western edge of the Rio Grande Trench and
the fringing Las Animas Hills, near lat 33 N. in
New Mexico, display four gravel units, according
to Kenneth Segerstrom and J. C. Antweiler III.
These are:

1. A calcite-cemented deposit that occurs in the sub-
surface east of the hills and in eroded remnants
on the flanks of the hills. The probable age is 7 to
9 my (latest Miocene or earliest Pliocene).

2. An ow rlapping gravel that mantles piedmont
slopes descending eastward toward the Rio
Grande and contains as many as four or five soil-
calcite layers. This thick fill deposit is about
500,000 yr old (mid-Pleistocene).

3. A gravel unit, lenticular in cross section and with
.one or two buried soil-caliche layers, that partly
fills shallow valleys cut in the No. 2 deposit. This

MINERAL-RESOURCE AND MINERAL-FUELS INVESTIGATIONS 3

unit is of late Pleistocene and (or) early Holocene
age.

4. Modern stream deposits without carbonate ce-
ment.

Vertical channel samples from trenches and
stream-cut banks in units 1, 2, and 3 consistently
have visible gold in pan concentrates as far as 3 km
east of the Animas Hills. Gold is Visible in pan con-
centrates from unit 4 as far as 15 km east of the
Animas Hills, but not consistently.

A law cauldron subsidence feature at Silver Cliff-Johnson
ulch

A gravity study and careful consideration of sur-
face geology by W. N. Sharp led to identifying a
previously unrecognized subsidence cauldron 4.8 km
northeast of Silver Cliff, Colo. At the surface,
an oval-shaped depression, 1.6x2.4 km in size, is
marked by thin-bedded to massive white rhyolitic
water-laid tuff. This rock unit was mapped as early
as 1883 by Whitman Cross (1896, p. 322) and de-
scribed as “. . . a local and unimportant lake-bed
deposit. The surface geology is deceptive. The tuif
unit occupies a generally depressed area in the
moderately dissected Precambrian gneisses. Two
sides of the tufl" unit are bounded by intersection
faults. The low scarps of these structures“ and the
modest-appearing offset allowed a small collecting
basin to preserve the tuff beds.”

The geologic evidence showing that the Precam-
brian gneisses are the walls of a subsided cauldron
is modest but in order. The tufl" beds dip inward
along the contact in the few places that they can be
seen. In one place, the contact is marked by a zone
of coarse breccia—mostly Precambrian rocks with
some volcanic blocks, tightly packed, angular, and
all stained and highly weathered. This unit appears
to be breccia associated with collapse. Precambrian
rocks at and near the contact are fractured at many
places and sufficiently iron stained to attract pros-
pecting. At one such place the fractures are filled
with black manganese-iron oxides, a common occur-
rence at the neighboring Silver Cliff volcano.

Gravity measurements made during a survey of
the Silver Cliff volcanic area gave conspicuously low
values at stations over the tuff, outlining an 8-mGal
low. A review of a low-altitude aeromagnetic survey
of the region showed a coinciding magnetic low. A
preliminary assessment of the thickness of the tuff
unit, from the average density contrast of the in-
volved rocks, indicates about 600 m of tufl'like ma-
terial filling a steep-walled structure in the Precam-
brian granite.

 

Minerals of economic interest in the Phosphoria Formation
vanidiferous zone, Afton, Wyoming

Electron microprobe studies by G. A. Desborough
of unweathered rocks from the vanadium-rich zone
in the Phosphoria Formation near Afton, Wyo., re—
vealed that cadmium-rich zinc sulfide, a calcium-

,molybdenum mineral, and a new titanium-iron-sul-

phur oxide are present.
Could Belt carbonates contain stratabound lead-zinc ores?

Can the concept of “infiltration” for the forma-
tion of stratabound lead-zinc deposits in carbonate
rocks be applied to the Precambrian Belt Super-
group? The concept specifies redistribution of lead
and zinc during diagenesis and dewatering of sedi-
ments where these metals are trapped. Recent geo-
logic mapping by J. E. Harrison in the south-central
part of the Wallace 2° sheet, Montana and Idaho,
revealed a typical carbonate sequence in the Helena
and the upper part of the Wallace Formation con-
sisting of carbonate shelf deposits in the east, slope
deposits including large slumps and sedimentary
breccia farther southwest, and black shale still far—
ther west. Some of the sedimentary breccia deposits
contain small replacement-type fluorite deposits
along with trace amounts of copper, lead, and zinc,
all of which suggest that the infiltration process
may have been active.

Chle’mifial characteristics of hydrothermal alteration at Bingham,
a

Chemical variations in igneous host rocks of the
disseminated copper ore body at Bingham, Utah, are
systematically related to the distribution of potas-
sium silicate (biotite : potassium feldspar) and
plagioclase-destructive sericitic (sericite : kaolinite
: montmorillonite) alteration assemblages, accord-
ing to W. J. Moore. Potassium silicate alteration is
present throughout the copper ore zone. Primary
pyroxene and amphibole in equigranular monzonitic
rocks from the southeastern half of the ore zone are
totally replaced by hydrothermal biotite (average
magnesiumzmagnesium + iron, 0.74). Chemical
changes between these rocks and their unaltered
equivalents include a slight gain in silica and a
moderate loss of A1203, Fezog, and CaO; FeO, MgO,
Na20, and K20 are generally unchanged, although
K20 is added locally.

Hydrothermal orthoclase is a prominent phase in
potassium silicate assemblages from the aplitic por-
phyry. Bulk compositions of these cryptoperthitic
feldspars (Oral) are more potassic than those from
unaltered monzonitic rocks (01'73). Determinations
of structural state for hydrothermal orthoclase in-
dicate an intermediate degree of aluminum-silicon

4 GEOLOGICAL SURVEY RESEARCH 1975

ordering. Cooling of the hydrothermal system
through the microcline stability field (T=4,000°C)
was rapid enough to preclude an inversion to tri-
clinic forms.

Pervasive sericitic alteration is largely confined to
host rocks from the northwestern half of the ore
zone. This alteration was superimposed upon the
potassium silicate assemblage as the hydrothermal
system cooled. Rocks from the sericite zone show
substantial gains in silica and potassium oxide rela-
tive to those from the southeastern half of the ore
body; all other major elements show losses.

In monzonitic rocks peripheral to the ore zone,
primary pyroxene is commonly rimmed or totally
replaced by fibrous (uralitic ?) amphibole, and
plagioclase crystals are rimmed by orthoclase. These
reactions apparently predated the main period of
hydrothermal activity and signify a new direction
of magmatic evolution leading to the generation of
hydrous fluids responsible for successive stages of
potassium silicate and sericitic alteration.

Age of volcanism, intrusion, and mineralization in western
Utah

The history of volcanism, intrusion, and mineral-
ization in J uab County, western Utah, was outlined
by D. A. Lindsey, C. W. Naeser, and D. R. Shawe
with the aid of 26 new fission-track age dates. Three
distinct ages of volcanic and intrusive rocks were
established: (1) volcanic flows and ash-flow tufl’s
at 38 to 39 m.y., (2) ash-flow tuffs and intrusives at
30 to 32 m.y., and (3) alkali rhyolite flows at 6 to
10 my. Fluorspar and beryllium mineralization at
Spor Mountain followed extrusion of topaz rhyolite
6 my. ago.

Complex igneous and mineralization history at Round
Mountain, Nevada

Geologic mapping has clarified the complex his-
tory of igneous activity and mineralization in the
Round Mountain area of Nevada, according to D. R.
Shawe. About 3 km southeast of the town of Round
Mountain, a swarm of northeasterly oriented rhyolite
dikes of Oligocene age intrudes Cretaceous granite
that was cut by veins of quartz tungsten in Late
Cretaceous time. Locally intense mineralization that
followed intrusion of the rhyolite dikes possibly ac-
counts for metal anomalies (as much as 1,550 ppm
Mo and 15,000 ppm Cu) in the vicinity of the dikes.
A small biotite diorite stock was emplaced near the
northeastern‘end of the swarm of rhyolite dikes.
Tourmaline found in granite and rhyolite near the
diorite stock was probably formed during or shortly
after the intrusion of the stock.

 

A volcanic mélange unit, consisting of blocks of
large size and compositional variety in an ash-tufl"
matrix, was deposited in the northern part of the
Round Mountain quadrangle and probably was de-
rived from a volcano at Jefferson, 2 km east of the
quadrangle. Extensive rhyolitic ash-flow tufl’s de-
posited in early Miocene time probably were de-
rived from the Mount Jefferson volcanic field north-
east of the quadrangle. Gold mineralization in the
rhyolitic welded tufi‘ at Round Mountain occurred
about 1 my after emplacement of the tufl’.

Bedded barite in southwestern Nevada

Sedimentary barite deposits of Cambrian and Or-
dovician age were reported by F. G. Poole in the
southern Montezuma Range and southwestern Can-
delaria Hills of southwestern Nevada. The barite in
the Montezuma Range occurs as fine-grained con-
glomeratic barite interbedded with limestone, silty
limestone, and minor chert. The major barite bed is
more than 1 m thick and is associated with a silty
limestone unit that contains fragments of Lower
Cambrian trilobites. In the Candelaria Hills, lam-
inated to very thin bedded dark fine-grained barite
in beds as much as several metres thick is inter-
calated with eugeosynclinal dark mudstone and
chert of Ordovician age.

Genesis of turquoise deposits, Shoshone Range, Nevada

Studies by C. T. Wrucke and R. A. Koski showed
that turquoise (a copper-bearing phosphate) in the
northern Shoshone Range, Nev., occurs mainly
along steep faults and thrust zones at the fringes of
areas mineralized in gold and base metals. Host
rocks are eugeosynclinal siltstone, argillite, and
chert of Paleozoic age. Other phosphate minerals in
the same environment but not occurring together
are crandallite, variscite, and goyazite(?); all are
from veins and fillings between fault breccia. Asso-
ciated minerals include quartz, sericite, and kaolin-
ite. Phosphate for the turquoise could have been de-
rived from sparse but Widespread phosphorite in the
eugeosynclinal rocks, but whether deposition was by
supergene processes, to which it is usually ascribed,
or by a low-temperature hydrothermal event asso-
ciated with hot springs is uncertain. Some gold
mineralization in the area is thought to be of hot-
spring origin.

Features of Carlin-type gold deposits

Collaborative studies by A. S. Radtke (USGS) and
F. W. Dickson (Stanford Univ.) indicated that the

MINERAL-RESOURCE AND MINERAL-FUELS INVESTIGATIONS 5

fine-grained, disseminated gold deposits designated
as Carlin-type deposits were formed by the action of
ascending hot waters that penetrated tothe surface
or to shallow depths. Conditions during ore deposi-
tion ranged from the low temperatures and pres-
sures of a hot-spring environment to epithermal
conditions of as‘much as 225°C and 25 bars. The
Carlin-type deposits constitute a previously unrec-
ognized class of ore deposits. They are characterized
by the association of gold, pyrite, silica, and organic
carbon; exceedingly fine-grained ore minerals; in-
troduced organic compounds; localization of gold in
brecciated, carbonaceous, silty carbonate rocks and
along high—angle faults that commonly contain al-
tered dikes; fine-grained silicified rocks and jasper-
oids; and' argillized rocks. Visible gold is rare, and
base-metal minerals are uncommon. Abnormally
large amounts of arsenic, antimony, and mercury
occur in the gold ore and in the surrounding country
rocks. Thallium occurs in high-arsenic ores. Most
deposits contain veinlets of quartz, barite, and cal-
cite. Pyrite occurs as preore syngenetic or diage-
netic grains in host rocks and with the ore and also
was deposited from the hydrothermal solutions be-
fore and possibly during gold deposition.

Ore deposition was in response to drops in tem-
perature‘and pressure, reaction with wall rocks, and
boiling. Boiling took place over a vertical distance
of at least 100 m and perhaps as much as 300 m.
During the waning stages of hydrothermal activity,
the upper level of boiling lowered progressively, and
previously mineralized rocks were thus exposed to
oxidation. Soluble compounds produced by oxidation
migrated downward to react with the hydrothermal
solutions and to form late sulfate and carbonate
mineral veins.

Stocks and metal dep05its in the Santa Catalina Mountains,

Arizona

Geologic mapping by S. C. Creasy and T. G. Theo-
dore in the Santa Catalina Mountains, Ariz., sug-
gested that the base-metal deposits are spatially
and probably there-fore genetically related to the
Leatherwood Quartz Diorite and not to the younger,
highly sheared Samaniego Quartz Monzonite. The
large volumes of pegmatite-aplite probably derived
from the Samaniego Quartz Monzonite indicate a
water-rich magma. Mineralogic differences Within
the Samaniego Quartz Monzonite are probably re-
lated to compositional differences in the contiguous
country rocks. The existence in the heart of the
Arizona copper province of an ore-poor quartz mon-
zonite derived from a hot, water-rich magma is

 

noteworthy. The economic significance, if any, of
the intense deformation that transformed much of
the Samaniego Quartz Monzonite into a gneiss is
not known.

Fluid inclusion studies on ore from Ray, Arizona

Preliminary study by T .G. Theodore of fluid in-
clusions in quartz-bearing ore collected by N. G.
Banks from the porphyry copper deposit at Ray,
Ariz., yielded results different from those typical of
most such deposits. Most significantly, at Ray there
is a marked paucity of the gas—rich varieties and
polyphase types of inclusions common in many other
porphyry copper deposits. Fluid inclusions of both
primary-pseudosecondary and definitely secondary
origins at Ray are unsaturated at room temperature
with respect to sodium chloride (<26 weight per-
cent sodium chloride equivalent), and they are com-
posed primarily of liquid plus a small vapor bubble.
All inclusions yield relatively low filling tempera-
tures, with a range of 195° to 350°C and an approxi-
mate mean of 270°C, irrespective of host-rock or
sulfide-vein mineralogy. Paragenetically late galena—
sphalerite—pyrite-quartz veins yielded some of the
highest filling temperatures; this relation is some-
what enigmatic because thermal declines with time
are ascribed to most such sulfide-silicate systems.
Actual trapping temperatures, however, may have
been much higher than these temperatures because
of potentially large corrections to filling tempera-
tures required by the uncertain pressure environ-
ment during metallization.

Laramide plutonism and mineralization west of Safford,

Arizona

Recent mapping by P. M. Blacet in the Santa
Teresa and Turnbull Mountains, northwest of Saf-
ford, Ariz., demonstrated that the Santa Teresa
Granite and the Goodwin Canyon Quartz Monzonite
are mutually gradational facies of an early Ter-
tiary( ?) batholith exposed over an area of approxi-
mately 330 kmz. This unusually large epizonal plu-
ton, probably the largest mass of Laramide granitic
rock exposed in Arizona, intrudes rock at least as
young as the Pinkard Formation of Upper Creta-
ceous age and has an apparent lead-alpha age of
60:10 my. (Simons, 1964).

Disseminated pyrite and chalcopyrite occur in
altered coarse-grained granite at several localities
in the south-central part of the batholith. Small re-
placement deposits of magnetite and the manganese
pyroxene johannsenite were discovered in skarn de-

6 GEOLOGICAL SURVEY RESEARCH 1975

veloped from lower Paleozoic limestone and shale in
a roof remnant in the central part of the batholith.

South of the batholith, in the Eagle Pass area, a
swarm of Laramide( ?) porphyry dikes is associated
with widespread alteration and mineralization. Ex-
otic secondary copper minerals apparently have
leaked through a Miocene thrust plate that covers
the western part of the dike swarm 18 km southeast
of Klondyke. The dike swarm is interpreted as part
of a major Laramide tectometallogenic zone trending
approximately N. 70° E. through San Manuel, Saf-
ford, and Morenci. This belt occupies a central po-
sition in the famed copper quadrilateral and is the
locus of three of the largest porphyry copper dis-
tricts in the United States.

GEOLOGIC STUDIES IN POTENTIALLY
MINERALIZED AREAS

AREAL MINERAL APPRAISAL

Black sands in the Lake Superior beaches

A geochemical surVey in the Michigan part of the
Sault Ste. Marie 2° quadrangle to find areas that
may have potential for economic metallic and non-
metallic deposits was conducted by J. W. Whitlow,
J. F. Windolph, T. W. Broadhead, and D. L. Pear-
son. Dark-gray to black sands in a bed or beds up
to 30 cm thick in the beaches along the south shore
of Lake Superior were found to contain as much as
11 percent Ti02, 0.2 percent V, and greater than
20 percent Fe. No other areas with potential for
ores of metals were found.

Geochemical sampling indicates belt of copper mineralization

in Calamine quadrangle, Lafayette County, Wisconsin

Chemical and semiquantitative spectrograph'u:
analyses of soil and stream sediment samples col-
lected by W. S. West showed a belt of copper min-
eralization at least 12.9 km long extending north-
south across the Calamine quadrangle, Wisconsin.
The mineralized belt may extend northward to the
copper occurrence at Mineral Point and southward
to the Apple River quadrangle.

The north-south trend of this copper mineraliza-
tion contrasts with the general east-west trends of
the lead and zinc mineralization in the Upper Mis-
sissippi Valley district.

Copper potential in the eastern half of the Tucson 2°
quadrangle, Arizona

A map showing the relative potential for the
occurrence of copper deposits in an area of more

 

than 10,000 km2 extending from the Tucson Moun-
tains to Sulfur Springs Valley near Willcox, Ariz.,
was prepared by the US. Geological Survey (1974)
for use by land-use planners, governmental agen-
cies, conservation groups, and companies or indi-
viduals interested in the mineral industry, accord-
ing to P. M. Blacet. The map outlines areas of rela-
tively high, intermediate, and low potential for
hosting copper deposits and, to a lesser extent, in-
dicates favorable areas in which to explore for asso-
ciated zinc, lead, gold, and silver deposits. The zones
of relative mineral potential are plotted on a sim-
plified geologic map along with the locations of
known copper deposits and minor copper occur-
rences. The map is the second of a series planned
for part of southern Arizona to. classify. land accord-
ing to its relative mineral potential.

Mineralization in Hillsboro area, New Mexico

Geologic maps of the Hillsboro-San-Lorenzo 15-
min quadrangles New Mexico, were completed in
1974, and three selected mineralized areas were
mapped in detail. D. C. Hedlund reported that three
areas of detailed resource mapping were the Copper
Flat copper porphyry in the Animas Hills district
(126,000 and 1 :24,000) , the Kingston silver district
(1:6,000), and base-metal deposits in the Swartz
(Carpenter) mining district (1:24,000).

The small quartz monzonite body of Copper Flat
is a relatively nonweathlered subvolcanic stock that
has intruded andesite and andesite breccias of Late
Cretaceous age. The stock has an area of about
1.0 km2 and, on the basis of limited drill-hole data,
appears to have steeply expanding contacts with
the surrounding andesite. ‘Biotite from the quartz
monzonite has been dated by the K-Ar method as
73.4:25 m.y. (R. F. Marvin, H. H. Mehnert, and
V. M. Merritt, unpub. data, 1974). The copper min-
eralization is confined mainly to the altered central
part of the intrusion where numerous fracture fill-
ings and disseminations of pyrite, chalcopyrite, and
bornite are localized in the sericitized quartz mon-
zonite. I

In the Kingston district, fissure veins that con-
tain silver-bearing base metals are localized along
major faults that strike N. 10°—20° W. The silver
content of the unoxidized ores is as much as 790
ppm and averages about 440 ppm (six analyses).
The chief silver minerals are cerargyrite, argentite,
and polybasite; the galena is argentiferous and con-
tains as much as 1,300 ppm Ag. Other ore minerals
include sphalerite, pyrite, chalcopyrite, and alaban-

MINERAL-RESOURCE AND MINERAL-FUELS INVESTIGATIONS 7

dite. The sphalerite contains exsolution-type blebs of
chalcopyrite, and electron microprobe analyses of
the pyrite-associated sphalerite indicate 1.91 to 2.40
mole percent FeS. This low FeS content suggests
relatively low depositional temperatures.

Sphalerite-rich base-metal deposits of middle Ter-
tiary age (about 33 m.y.) are localized along strong
faults that strike N. 10°—20° W. through the Swartz
mining district. Both fissure veins and bedding re-
placement bodios are also closely associated with a
zone of thermal metamorphism that extends for at
least 9.7 km along the strike of faulted Paleozoic
carbonate rocks. The contact metamorphic assem-
blage of diopside, epidote, tremolite, wollastonite,
grossular garnet, phlogopite, fluorite, helvite, and
magnetite suggests temperatures of about 500°—
650°C under very small load pressures. This thermal
metamorphism preceded the mineralization, but
both events are attributed to the intrusions of rhy-
olite stocks, plugs, and dikes into the Paleozoic
strata.

MINERAL INVESTIGATIONS RELATED TO THE
WILDERNESS ACT

The Wilderness Act of 1964 directs the Secretary
of Agriculture and the Secretary of the Interior to
review the suitability of lands being considered for
inclusion in the National Wilderness Preservation
System. To aid in evaluating suitability for wilder-
ness inclusion, the USGS and the U.S. Bureau of
Mines are making mineral—resource appraisal sur-
veys of primitive and other areas of the national
forests, as well as of wilderness areas established
by the Act.

PRIMITIVE AREAS

Mineral surveys have been completed on all 34
primitive areas, totaling about 2.9 million ha. Re-
ports on 31 of the areas have been published as
USGS Bulletins, and reports on the remaining three
were open filed during 1973; they will be printed dur—
ing 1975 and 1976.

WILDERNESS AREAS

Mineral surveys have been completed on 15 of the
54 wilderness areas that were established before or
by the Wilderness Act of 1964. A report on the
Scapegoat Wilderness, Mont, was published in
1974, and a report on the San Pedro Parks Wilder-
ness, N. Mex., was published in 1975. Field work
has been completed and the reports are in prepara-

 

tion in five wilderness areas, and field work is un-
derway in three areas.

Maroon Bells-Snowmass

Geologic mapping in the Maroon Bells-Snowmass
Wilderness Area of Colorado by V. L. Freeman and
Bruce Bryant demonstrated Oligocene faulting
along Avalanche Creek in the Redstone quadrangle.
The fault that extends from the intrusions asso-
ciated with Mount Sopris on the north to the Snow-
mass pluton at the south trends north-northwest, is
probably nearly vertical, and has a displacement of
about 100 m, the southwestern side being relatively
unlifted. Some right-lateral movement is possible.
Movement along the fault occurred prior to or con-
temporaneously with intrusion of granodiorite o-f
Oligocene age.

STUDY AREAS

Mineral surveys of 77 of the 295 areas being
studied by the Forest Service for the Wilderness
System have been completed. Investigations of 13
of the completed study areas are included in reports
on primitive and wilderness areas. An Eastern Wil-
derness Act signed in 1975 established 17 study
areas to be studied in 5 yr. Studies of three areas
are complete, and the study of one area is in pro-
gress.

Open-file reports have been released for the Saw-
tooth Recreation Area, Idaho; the Trinity Alps addi-
tion, Calif; the Du Noir area, Wyo.; and the Cougar
Lakes-Mount Aix and Alpine Lakes additions,
Wash. Results from some of the areas are given
below.

Boulder Pioneer study area, Idaho

Dominantly allochthonous rocks underlie about
2,500 km2 in the Pioneer Mountains, Idaho. J. H.
Dover, S. W. Hobbs, W. E. Hall, F. S. Simons, C. M.
Tschanz, and R. J. Ross, J r., recognized at least six
major thrust plates of Paleozoic sedimentary rocks,
each with its own distinctive stratigraphic sequence
and (or) structural-metamorphic style. Parautoch-
thonous ( ?) Precambrian gneiss and lower to middle
Paleozoic shelf sediments are exposed in three struc-
tural windows. Evidence is accumulating that major
structures of Antler (mainly Mississippian) age
have been moved into the Pioneer Mountain area
upon large thrust faults of Mesozoic age. Cumula-
tive crustal shortening of at'least some tens of
kilometres, and perhaps as much as 150 km, is sug-
gested by reconstruction of early Paleozoic paleofa-

8 GEOLOGICAL SURVEY RESEARCH 1975

cies combined with intense deformation over an ex-
tensive area within the allochthons.

Eastern part of Sawtooth National Recreation Area, Idaho

The eastern part of the Sawtooth National Rec-
reation Area covers about 2,100 km2 in central
Idaho. The mineral-resource study was done by C. M.
Tschanz, T. H. Kiilsgaard, and D. A. Seeland (USGS)
and R. M. Van Noy, James Ridenour, N. T. Zilka,
F. E. Federspiel, R. K. Evans, E. T. Tuchek, and
A. B. McMahon (US. Bureau of Mines) (1974).

The geology of the area is complex and consists
of deformed and metamorphosed sedimentary rocks
that have been intruded by granitic rocks and over-
lain by volcanics, glacial deposits and alluvial de-
posits. The study area is near the southeastern mar-
gin of the composite Idaho batholith, which under—
lies the northwestern third of the area and encloses
the smaller, younger Sawtooth batholith immedi-
ately to the west. The Idaho batholith intrudes
metasedimentary rocks of probable Precambrian
age in the northwestern part of the area. Folded
and faulted sedimentary rocks that range in age
from Ordovician to Permian form an arcuate belt
trending northerly through the center of the area
and are intruded by the Idaho batholith, the White
Cloud, Horton Peak, and Boulder Mountains stocks,
and by several smaller stocks. In most of the eastern
third of the area, the sedimentary rocks and intru-
sives of the composite Idaho batholith are overlain
by the Challis Volcanics and intruded by hypabyssal
porphyries that are related to the volcanics.

The area is in one of the most highly mineralized
and potentially productive regions in Idaho and con-
tains large undeveloped mineral resources. The
mineral evaluation of the area is based on the past
mineral production, the results of recent exploration
by claim owners, and the results of this study. The
value of past mineral production from the area, at
prices prevailing at the time of production, is esti-
mated from incomplete records to be at least $5
million. The total estimated production from mining
districts within 16 km of the study area exceeds
$50 million.

The potential value of known mineral resources
in the area exceeds the value of the total past pro-
duction by a factor of between 70 and 100. The most
important deposits are large marginal resources
of molybdenum near Boulder Creek and large re-
serves of zinc recently determined in the Hoodo
Mine; cadmium occurs with the zinc and adds appre-
ciably to the value of the large reserves. Many
tungsten, molybdenum, and uranium deposits have

 

been discovered or developed since 1952 in accessible
areas within or near the study area. The principal
resources, in estimated order of decreasing potential
value, are molybdenum, zinc, silver, gold, lead,
fluorite, antimony, cadmium, and graphite. Niobium,
uranium, thorium, rare earths, and titanium are
potential coproducts of placer gold mining. Small
amounts of tin, tungsten, bismuth, mercury, selen-
ium, and tellurium also occur in the area.

Target areas that may contain additional mineral
resources were indicated by the results of geochemi-
cal and geophysical surveys. The most promising
are zinc anomalies at Mill Creek and at several
streams in the Slate Creek drainage, Where zinc-
cadmium deposits similar to the deposit at the H00-
doo Mine are inferred in the Mississippian and De-
vonian( ?) rocks, and zinc and silver-lead anomalies
at Grand Prize Gulch. The results of electromag—
netic surveys indicate conductors that may repre-
sent mineralized zones in these areas, as well as in
the Buckskin and Valley Creek mine areas near the
northern boundary, where gold-silver-bearing veins
are present.

Some silver-lead-bearing veins in the area con-
tain small amounts of tin in the form of cassiterite
and stannite. The present economic value of the tin
resources is uncertain; however, these deposits are
unique in the United States, and they are a possible
future source of this domestically rare, important
metal.

Cougar Lakes-Mount Aix study area, Washington

The Cougar Lakes-Mount Aix study area covers
approximately 673 ka, chiefly along the eastern side
of the crest of the Cascade Range on the east of
Mount Rainier National Park in Yakima and Lewis
Counties, Wash. The mineral-resource study was
done by G. C. Simmons (USGS) and R. M. Van Noy
and N. T. Zilka (US. Bureau of Mines).

Most of the study area is underlain by volcanic
and intrusive rocks; perhaps 10 percent are under-
lain by older sedimentary rocks. These rocks are
intruded by younger granitic rocks followed by
rhyod-acite. Most of the mineralization is in pyri-
tized and altered zones along the margins of the
younger intrusives. Following intrusion and min-
eralization, the area was alternately eroded and
partly covered during three periods of volcanism.
The area contains small, uneconomic deposits of
copper, mercury, zinc, and manganese, and the only
potential for a large metalliferous body is near
Mesatchee Creek, in an area that is presently being

MINERAL-RESOURCE AND MINERAL-FUELS INVESTIGATIONS 9

explored for copper. A small amount of mercury
was produced from the Red Spur mine, and small
shipments of manganese ore reportedly have been
made from the Fig property, both in the southeast-
ern part of the area. Although the exposed mercury
occurrences are submarginal, the potential for dis-
covering other small deposits of this metal exists in
the area. A potential zinc resource exists in the area
near Little Twin Sister Lake. In the Miners Ridge
district, outside the study area, copper, silver, and
tungsten were mined from northwesterly striking
shear zones that extend toward the crest of Miners
Ridge and possibly into the study area.

Data on the geology and analyses of spring water
indicate that part of the area may have a potential
for geothermal energy.

Alpine Lakes study area and additions, Washington

The Alpine Lakes study area and additions lie
along the crest of the central Cascade Range in
Chelan, King, and Kittitas Counties, Wash. The
mineral-resource evaluation of the study area and
additions, consisting of 1,551 kmz, was done by J. L.
Gualtieri and G. C. Simmons (USGS) and H. K.
Thurber, M. S. Miller, A. B. McMahan, and F. E.
Federspiel (US. Bureau of Mines).

The area is divided into an eastern block and a
western block by the northwest-trending anastomos-
ing Deception Creek Fault; the eastern block is
characterized by pre-Cretaceous metamorphic rocks
of granitic, mafic, and ultramafic composition that
are cut by thrust faults and minor high-angle faults.
The western block is characterized by late Mesozoic
and Tertiary sedimentary, volcanic, and granitic
rocks with only minor amounts of pre-Cretaceous
rocks. Most of the mineralization is in highly altered
shear zones and veins near the Mount Stuart bath-
olith of Cretaceous age and the Snoqualmie batho-
lith of late Miocene age.

The mineral evaluation is based on reconnaissance
geologic mapping, geochemical sampling, an aero-
magnetic survey, and examination of mines, pros-
pects, and claims. The drainage basins of Gold
Creek, Mineral Creek, Van Epps Creek, Lemah
Creek, and the Snoqualmie River have a potential
for low-grade copper resources in mineralized bree-
cia zones. Granitic rocks in the Gold Creek Valley
area may contain disseminated copper sulfide min-
erals at depth. Several vein-type mineral deposits
are in the area; some of them contain moderately
high values of copper and silver, and some contain
minor amounts of gold.

 

A poorly defined zone of disseminated copper de-
posits appears to extend from the area of the Sno-
qualmie River southward through the Gold Creek
area to the Mineral Creek area.

The Porter-Crawford Creek area has a potential
as a large low-grade copper resource. The Porter-
Hemlock-Condor mineralized zones are presently
being explored, and they may contain large commer-
cial deposits of copper. The Three Brothers zone
may contain as much as 1.8 million tonnes of min-
eralized rock averaging 0.8 percent Cu. The Red
Face.mineralized zone of low-grade disseminated
copper may be a potential resource.

Anomalous stream sediment and rock samples
from Big Creek, Cougar Creek, Lennox Creek, the
Miller River, and Gouging Lake areas suggest the
presence of undiscovered vein deposits of silver,
copper, and molbydenum. The Cleopatra mine is
estimated to contain over 90,000 tonnes of mineral-
ized rock grades ranging from 187.5 to 531.3 mg of
silver per kilogram. Detectable amounts of gold
were found in many places in the study area, but
only the Lennox mine in the Lennox Creek drainage
has produced gold ore

MINERAL COMMODITY APPRAISAL

Summary of the principal findings of Professional Paper 820

The encyclopedic nature of “United States Mineral
Resources” (USGS Professional Paper 820) seems
to have inhibited its widespread use by people other
than professional geologists. A summary of the
principal findings and conclusions of Professional
Paper 820 is presented in Circular 698 (W. D. Pratt
and D. A. Brobst, 1974), which gives special regard
to the resources of 27 mineral commodities of ma-
j or importance to our industrial civilization (on the
basis of dollar value) and to the problems involved
in using the resources of the 10 most important non-
ferrous metals, the 11 principal ferrous metals, and
the 6 principal fossil and nuclear fuels.

New appraisal of alunite resources

A reappraisal of alunite resources in the Western
States by R. B. Hall was stimulated by revived in-
terest in nonbauxite sources of aluminum. Depos-
its at Marysvale, Utah, well studied during both
World Wars as a potential source of aluminum and
potash, are insufficient to serve as a long-term re-
source; however, recent exploration by a private
consortium has found large reserves in Tertiary
volcanic terrane in Beaver County, Utah, that place

10

alunite in a more favorable light as a possible do-
mestic source of aluminum and a partial alternative
to imported bauxite. Potassium sulfate fertilizer
and sulfuric acid are potential byproducts, the re-
covery of which is essential to the economic utiliza-
tion of alunite ore. Large tonnages of alunite-bear-
ing rock exist in solfatarically altered volcanic
rock-s of Tertiary age in southern Nevada, southern
Arizona, and the San Juan Mountains of southwest-
ern Colorado, but the tenor in these deposits is not
known. Alunite-processing technology seems well
established, although its economic feasibility is not
yet proven. Pilot plant testing of Utah ore by a
private consortium has been in progress for several
years.

Chemical differences between types of ultramafic bodies

M. L. Bird, in a microprobe study of ultramafic
rocks, found that the differences in composition
of chromite, olivine, and pyroxene, the respec-
tive trends in cbmpositional variation, and the
major-element distribution between the respective
minerals serve to distinguish the alpine, strati-
form-, and concentric-type ultramafic bodies. The
platinum-containing concentric-type bodies can be
distinguished from the alpine type, and, within the
alpine type, those bodies that may contain metal-
lurgical-grade chromite can be distinguished fro-m
those containing refractory-grade chromite. Strati-
form bodies that may contain sulfides are distin-
guished from the other types.

Fluorspar districts controlled by major tensional faults

Review of the principal fluorspar districts of the
United States by R. E. Van Alstine showed that
they are associated with continental rifts and other
major zones of tensional faulting. In Illinois and
Kentucky, the deposits are along and near thejunc-
tion of the New Madrid and Shawneetown-Rough
Creek fault zones. In the Rocky Mountains, they are
along and near the Rio Grande rift zone and its
northward projection to the Canadian border. In
Nevada and Utah, the deposits are in tensional faults
of the Basin and Range province.

The western deposits commonly are located in
high-angle normal faults, are low-temperature and
low-pressure types, have silicified wall rocks, and
are middle to late Tertiary in age. Locally, the de-
posits or their controlling structures are associated
with Tertiary silicic or alkalic intrusive rocks, flows
or hypabyssal bodies of basalt, silicic or alkalic
rhyolitic volcanic rocks, calderas, hot springs, and

 

GEOLOGICAL SURVEY RESEARCH 1975

gravity-low areas. The high heat flow in and near
the tensional structures suggests that magma and
volatiles were transferred upward; volatile fluorine
from the mantle or lower crust probably was the
ultimate source for the near-surface fluorspar de-
posits.

Commercial fluorspar deposits are associated with
zones of tensional faulting elsewhere in the world:
for example, Mexico, the Rocky Mountain trench of
Canada, the rift zone-s of Africa, and the Rhone
and Rhine grabens of Spain, France, and Germany.

Tools for prospecting for vermiculite

Vermiculite deposits are associated with ultra-
mafic rocks and are formed in the zone of weather-
ing. About one-third of our production comes from
South Carolina, where Weathering is deep, the rocks
generally are not well exposed, and the ultramafic
bodies have areas of only a few hectares. The mag-
netic susceptibility. of ultramafic rocks is commonly
greater than that of granitic rocks, so that A. L.
Bush suggested that aerom-agnetic survey might pin-
point anomalies caused by the ultramafic bodies. A
survey of about 650 km2 in Laurens County, 8.0.,
revealed about 20 anomalies, but field examination
showed that susceptibility contrasts were too low
to distinguish between ultramafic and granitic rocks
associated with the vermiculite deposits, and the
amonalies could not be used to identify potential
ultramafic host rocks.

Western termination of Negaunee Iron-Formation

The Negaunee Iron-Formation (Precambrian X)
is the principal iron-producing unit of the Marquette
Iron Range in northern Michigan. In the past, it has
yielded ore as far west as the town of Michigamme.
Westward from that point, the unit thins rapidly
from about 150 m just west of Michigamme to 45
m or less within about 1 km along strike, according
to W. F. Cannon. Still farther west, the Negaunee
is not exposed but has been traced by magnetic
surveys for about 8 km. Near the town of Three
Lakes, about 5 km west of Michigamme, several
diamond-drill holes penetrated about 15 to 30 m of
iron—formation, and a magnetic anomaly of about
10,000 gammas is caused by the iron-formation. The
anomaly is about 5,000 gammas 1.5 km farther
west, and it disappears completely within another
1.5 km.

Environmental impact of mining peat in Maine

C. C. Cameron (1975) determined from studies of
five physiographic forms of peat deposits in Wash-

MINERAL-RESOURCE AND MINERAL-FUELS INVESTIGATIONS 11

ington and southern Aroostook Counties, Maine,
that exploitation during the past 75 yr has made
little impact on the heath-covered dome-shaped bogs
that are best suited for the production of commer-
cial-quality Sphagnum moss peat. This exploitation
has so little effect because the peat was removed
from the parts of the domes lying above the regional
water table and because remaining remnants of
heath flora regenerated new peat. So long as a re-
gional ground-water table is little changed by keep-
ing drainage ditches at minimum depth and some
patches of heath flora are left undisturbed, peat min-
ing in sphagnum dome-shaped bogs, such as those
that occur in Maine, may not cause permanent
change. However, recent usage of modern machinery
for rapid clearing of the heath surface and for
ditching makes preliminary studies of the regional
and perched water-table positions and relationships,
the physiographic form of the deposit, and its biol-
ogy important in order to prevent unnecessary dam-
age to the environment.

Economic geology of phosphate deposits

Until recent years, only tonnage, P205 content, and
geographic location were enough to characterize,
economically, most phosphate deposits. Because most
phosphate rock today is used to make sophisticated
chemical fertilizers (for example, triplesuperphos-
phate, polyphosphate, diammonium phosphate, and
phosphoric acid), a great many other chemical
analyses must be made to determine the economics
and potential uses of phosphate rock from any de—
posit. Lime (CaO) in amounts greater than needed
in the apatite mineral is deleterious in acidulation
because of greater use of sulfuric acid and is de-
leterious in thermal phosphate manufacturing be-
cause of the need to add silica to turn all of the CaO
into calcium silicate flux. The ratio of Ca0:P205
in marine apatites is about 1.5; anything greater
than 1.5 indicates that some calcite is probably pres-
ent. Iron and alumina, as FeZO3 and A120,, are both
deleterious in making phosphoric acid or thermal
phosphates because of the formation of insoluble
aluminum and iron phosphates and the formation of
ferrophosphate. The total content of aluminum and
iron oxides in phosphate rock should be less than
about 3.5 percent, and the lower the better. Mag-
nesium oxide (MgO) in amounts greater than 0.2
percent is bad for the manufacture of phosphoric
acid. Chlorine in amounts greater than about 0.15
percent causes serious corrosion problems in the
manufacture of phosphoric acid. Organic material
should be less than 0.5 percent because of problems

 

with foaming when phosphate rock is acidulated
with sulfuric acid. Pyrite is deleterious because of
formation of hydrogen sulfide (HZS) on acidulation.
If any of these elements are present in amounts that
are too large, processing must be changed, or the
deposit may be uneconomic.

Certain minor elements either are being recovered
or could be recovered in processing phosphate rock.
For example, fluorine is being recovered as a by-
product; uranium was recovered from Florida phos-
phate rock, and plants are currently being built to
recover uranium. Vanadium has been recovered as
a byproduct in thermal processing of phosphate rock
in the western field, and the rare earths are present
in amounts that may be recoverable. It is, therefore,
necessary to analyze phosphate rock for these ele-
ments to determine if they can be recovered in
processing.

The elements B, Cu, Fe, Mn, Mo, and Zn are
required in very small amounts for optimum plant
growth. These so-called micronutrients are present
in most marine pho-sphorites in minor amounts but
are largely removed in chemical processing. They
must then be added to the final products for best
plant growth.

The carbon dioxide (00,.) content of the carbon-
ate fluorapatite, the apatite mineral of the marine
phosphorites, varies widely. The apatite mineral is
more soluble in acid ground water with increasing
amounts of 002, and, in addition, the high-002
apatites are easier to acidulate than the low-002
apatites. The amounts of C02 present in the apatite,
then, are a measure of how successful the particu-
lar rock may be in direct application to soil, and
the CO2 content may determine methods of chemical
treatment.

Thus, economic appraisal of a phosphate deposit
requires, today, very sophisticated chemical analyses
and considerable study by the geologist.

Lithium demand may soon exceed supply

The lightest of all metals, lithium, is currently in
short supply for conventional uses such as ceramics,
multipurpose greases, aluminum reduction, and ab-
sorption of carbon dioxide. Meanwhile, research on
rechargeable lithium batteries for electric vehicles
and off-peak power storage suggests that a vastly in-
creased demand for lithium may soon develop. Over-
shadowing these uses is the potential future require-
ment for lithium in thermonuclear power plants,
Where it serves as a source of the fuel element tri-
tium and also assists in the absorption of thermal
neutrons.

12 GEOLOGICAL SURVEY RESEARCH 1975

Although data on lithium production and con-
sumption are regarded as privileged information by
the industry, recent estimates suggest a 10 percent/
yr growth since 1968, when the production was esti-
mated at about 2.6><106 kg, or about 4.5><10‘s kg in
1974. If 10 percent of the autbmobiles produced in
the United States were to convert to lithium—battery
power, the demand for lithium could increase ten-
fold. The requirement for stationary lithium bat—
teries for off-peak power storage has not been de-
termined. Although the requirement for thermo-
nuclear powerplants varies with design, one typical
design calls for 930 kg of lithium per million watts
of electrical power (MWe). The anticipated 500,000-
MWe thermonuclear power capacity by the year
2020 would require 460x106 kg of lithium metal.
Thus, we are on the threshold of a tremendous po-
tential increase in the demand for lithium.

Our lithium resources are not as great as recent
published estimates have suggested. The Clayton
Valley brinefield near Silver Peak, Nev., is currently
estimated to contain a reserve of about 45><106 kg
of lithium, or about one-hundredth of the amount
suggested in preliminary estimates. Until new re-
sources can be developed, the anticipated discrep-
ancy between supply and demand will have to be
made up by increasing the rate of production of
spodumene from the Kings Mountain pegmatites,
which have total resources of about 500x106 kg.

Lithium in the Rocky Mountain region

Reconnaissance by E. B. Tourtelot throughout the
Rocky Mountain States suggested several areas of
abnormally high lithium content. The preliminary
data point to a relationship between lithium anoma-
lies and volcanic activity—for example, lithium
anomalies occur in the sedimentary rocks in the
moats of calderas. Anomalous amounts of lithium
also have been found in sedimentary rocks that have
been hydrothermally altered and in clays associated
with hydrothermal veins. Lithium apparently tends
to stay in solution and may travel further than
other ore metals.

The relationship between lithium, borates, and volcanic activity

Anomalous concentrations of lithium occur
throughout a large part of the Western United
States. Some of these anomalies are associated with
nonmarine evaporite deposits in both modern and
ancient closed basins, according to R. G. Bohannon.
The high ratio of lithium to sodium in most of these
deposits precludes any possibility of a simple origin
by concentration of seawater or by solution and re-

 

concentration of marine evaporites. The common
association of lithium with borates suggests the pos-
sibility of a common origin. One possibility is that
both lithium and boron are derived from late Ter-
tiary volcanic activity and the assoCiated geothermal
waters in areas such as the Long Valley caldera. "

Subsurface brines may be a source for lithium

Lithium is one of the most soluble alkali metals;
it tends to move in aqueous solution and remain in
a natural brine solution even beyond the precipita-
tion of potassium salts. Evaporation of seawater to
the stage at which potassium salts are precipitated
results in approximately 30 mg/l of lithium still in
solution, losses being caused by fluid inclusion in
precipitated salt. Collin (1974), in an article on po-
tential marketable minerals in oilfield waters, listed
seven localities with saline brines equal to or ex-
ceeding this lithium concentration. A limited review
of the literature by R. K. Glanzm‘an indicated that a
lithium concentration of 300 mg/l occurs in several
subsurface brines in the United States.

Cycling of platinum metals in the Stillwater Complex, Montana

N. J Page reported that platinum, palladium, and
rhodium analyses done by Joseph Hafi‘ty for basal
zone rocks of the Stillwater Complex, Mont, show
(1) a distribution of values that cycle or oscillate
in a manner similar to those of the rock types and
(2) chemical and physical properties of the silicate
and oxide minerals. This correlation of cyclic pat-
terns suggests that the chemical and physical param-
eters, such as magma composition, temperature, and
partial pressure of oxygen, that control the accumu-
lation of the rocks also exert some control over the
concentration of the platinum metals. Analogous
patterns of cycling for platinum metals were found
within an olivine cumulate unit of the ultramafic
zone in the complex.

New polymetallic tin province in central Idaho

A new province of polymetallic tin-bearing sulfide
veins was found during the evaluation of the mineral
resources of the Sawtooth National Recreation Area
by the USGS and the US. Bureau of Mines (C. M.
Tschanz and others, 1974). Narrow tin-bearing veins
in 35 silver-lead prospects form an arcuate north-
trending belt about 46.7 km long in Carboniferous
sedimentary rocks. The principal metals in these
veins are Ag, Pb, Zn, Sb, Sn, and smaller amounts
of Cu and Au. Ten veins contain at least 0.5 percent
Sn, and three locally contain 2 to 6 percent. Tin con-
tents greater than 0.7 percent are confined to two

MINERAL-RESOURCE AND MINERAL-FUELS INVESTIGATIONS 13

areas 19.3 km apart. In the northern area, the pre-
dominant valuable minerals are lead sulfantimo-
nides, sphalerite, and stannite and(or) cassiterite.
In the southern area (Galena district), the‘predorn—
inant mineral is galena, but, locally, as many as 25
metallic minerals are present, including many tin
and silver minerals.

Tin minerals studied by B. F. Leonard in one sam-
ple containing 2.2 percent Sn from the Galena dis-
trict include four minerals of the stannite family,
cassiterite, tellurium canfieldite, minute inclusions of
several unidentified sulfidic tin minerals in galena,
and the oxidation product termed varlamofli’oe. The
stannite family includes an unknown zincian stan-
nitelike mineral, kesterite (zinc analog of stannite) ,
“isostannite”(?), and “brown stannite”(?). Mic-ro-
probe analyses by G. A. Desborough indicated 7 per-
cent Zn in the unknown mineral and 15 percent Te
in the canfieldite. This occurrence of tellurium can-
fieldite, which is the principal silver mineral in the
specimens studied, is the third to be reported.

The tin-bearing silver-base—metal veins are un-
usual in the United States but resemble some pro-
ductive sulfidic tin deposits in Bolivia, Siberia, and
Canada. The only known comparable domestic de-
posits are those sampled by A. V. Heyl in the Delno
district, Elko County, Nev., but somewhat similar
deposits might be found in other western silver-lead
districts. Although the present economic value of tin
is doubtful, the Idaho tin province is one of few
potential domestic sources of tin that has not been
prospected thoroughly.

Titanium resources

Four investigators (Norman Herz, 1975; M. C.
Blake, Jr., and B. A. Morgan, 1975; E. R. Force,

1975) contributed reports discussing new types of ,

titanium resources or new viewpoints on old types.
Topics include: (1) partitioning of titanium between
silicates and oxides; (2) the relation between titani-
um placer deposits and the metamorphic grade of
source terranes; (3) rutile in blueschists; (4) titani-
um deposits in anorthosite; (5) titanium deposits in
alkalic rocks; and (6) titanium minerals in deposits
of other commodities. Alkalic rocks and blueschists
containing titanium minerals are new and potentially
major types of resources.

llmenite in Pleistocene beach sands of Virginia

E. R. Force has made a map at 1 : 250,000 of heavy
mineral resources in Pleistocene beach sands of
southeastern Virginia based on new mapping and on
existing mapping by R. Q. Oaks and N. K. Coch

 

(formerly of Yale Univ.) and by G. H. Johnson
(College of William and Mary). Fifty channel sam-
ples through the sand bodies were evaluated for re-
sources of titanium. Bodies of sand up to 12 m in
average thickness contain as much as 1 percent ilme-
nite and thus constitute marginal TiO2 resources.

Zeolites in Pliocene lacustrine rocks, Durkee basin, Baker

County, Oregon

Zeolites, potassium feldspar, silica minerals, and
clay minerals of diagenetic origin occur in altered
silicic tuffs of lacustrine deposit in the Durkee
basin, Oreg. According to R. A. Sheppard and A. J.
Gude III (1975), the zeolites are chiefly chabazite,
clinoptilolite, and erionite, although minor amounts
of analcime, phillipsite, and mordenite have been
identified. The zeolitic tufl’s are less than 1 cm to
about 2 m thick, but most are more than 15 cm thick.
Some of the relatively thick chabazite— and erionite-
rich tuffs have economical potential. Zeolitic and
feldspathic tuffs are restricted to the central part of
the ancient lake basin and to the lower half of the
stratigraphic section. Tuffaceous rocks in the mar-
ginal part of the basin contain fresh vitric material
that is locally altered to montmorillonite. Tuifaceous
beds in the upper half of the section consist mainly
of fresh glass and are interbedded with thick diato-
mite beds. Except for analcime, the zeolites are 10-
cally associated with relict glass. Neither analcime
nor potassium feldspar is associated with relict
glass. Textural evidence indicates that analcime
formed from chabazite, clinoptilolite, erionite, and
phillipsite; potassium feldspar formed from anal-
cime and .clinoptilolite. The distribution of zeolites
and other diagenetic silicate minerals in the tuffs is
due to the original chemical variations of the lake
water. Probably the water was relatively fresh in
the marginal part of the basin but increased in sal-
inity and alkalinity basinward.

Botential for metals in glauconitic sandstones

P. L. Weis and Helmuth Wedow, Jr., reported
that certain marine sandstones, chiefly those with a
strong glauconitic component, in the Eastern United
States have a potential for stratabound base-metal
deposits. Of particular import for copper are the
Lower Cambrian Rome Formation and its strati-
graphic equivalents in the Appalachian region from
Alabama to eastern Canada and the Upper Cam-
brian Franconia Formation in Wisconsin and Min-
nesota. Anomalous zinc appears to be widespread in
the Devonian' Huntersville, Oriskany, and Helder-
berg Formations in Pennsylvania, West Virginia,

14

and Virginia. In addition, gold has been reported
to be associated with greensands of the Franconia
as well as with those of the Mississippian Floyd
Knob Formation in Kentucky and in the Tertiary of
eastern Texas. The glauconite is deposited locally
with siderite in a mildly reducing iron-formation en-
vironment. It is postulated that this environment is
also especially favorable for the precipitation of
other metals, chiefly by entrapment of metals ions
in the rather open glauconite lattice. Introduction
of sulfur into this system from decaying organic
matter or by bacterial reduction of sulfate would

precipitate the metals as fine-grained interstitial sul-*

fides. Further concentration would result after early
remobilization and later reprecipitation in the pores
of early structural or stratigraphic traps or by later
movement into well-developed fractures and pores
formed during younger orogenic disturbances.

OFFICE OF MINERALS EXPLORATION

MINERALS DISCOVERY LOAN PROGRAM

Financial assistance on a participating basis to
private industry to explore deposits of certain min-
erals is offered by the USGS’s Office of Minerals Ex-
ploration (OME) under Public Law 85—701, ap-
proved August 21, 1958. Individuals or private firms
must meet the eligibility requirements of the pro-
gram, and approved project proposals must offer
reasonable geologic probabilities that significant dis-
coveries of ore may be made by the exploration work.
Contracts for the exploration work are prepared for
approved applications. Repayment of Government
funds expended on contracts and payment of simple
interest are made through a royalty of 5 percent on
the value of minerals produced from properties dur-
ing the period of the exploration work. If the Gov-
ernment issues a certificate of possible production
based on favorable results of completed contract
work, the obligationfor royalty payments continues
for not less than 10 yr or until the principal and in-
terest are repaid in full, whichever occurs first. No
repayment is required if there is no production, and
the Government is not obligated to purchase any
minerals produced.

At present, the following 27 minerals or metals
are eligible for Government participation in 50 per-
cent of the allowable costs of exploration:

Asbestos
Bauxite
Beryllium

Kyanite (strategic)
Manganese
Mica (strategic)

o

 

GEOLOGICAL SURVEY RESEARCH 1975

Cadmium Monazite
Chromite Nickel

Cobalt Quartz crystal
Columbium (piezoelectric)
Copper Rare earths
Corundum Selenium
Diamond (industrial) Sulfur
Fluorspar Talc (block steatite)
Graphite (crucible flake) Tellurium

Iron ore Thorium
Molybdenum Uranium

The following nine minerals or metals are eligible
for Government financial assistance in 75 percent of
of the allowable costs of explorations:

Antimony Rutile
Bismuth Silver
Gold Tantalum
Mercury Tin

Platinum-group metals

Combinations of the minerals or metals listed in
the 50- and 75-percent assistance groups may be
eligible for Government financial assistance in 62.5
percent of the allowable costs of exploration.

Activity on the OME program in calendar year
1974 and totals for the program through December
31, 1974, were as follows:

Calendar year Program totals,
1974 1953 through
Applications :

In process of review

Jan. 1, 1974 ________ 10
Received ______________ 5 1 945
Denied ________________ 1 387
Withdrawn or inactive" 13 350
Approved _____________ 1 208
In process of review

Dec. 31, 1974 ________ 0

Contracts:

Executed _____________ 1 208
Total value ___________ 2 $157,120 3 $13,281,354
Government share ______ 2 $75,770 3 $7,644,277
Disbursements ________ $138,313 a $4,775,897
Repaid to Government

through royalties on

production __________ $7,996 $412,933
Estimated recoverable

value of reserves at _ .

present metal prices .. $4 million $167 million

1 Total estimated cost of proposed exploration, $90 million.
2 Includes value added to an existing contract by two amendments.
3 Revised total.

Silver and gold exploration projects accounted for
about 66 percent of the total value of contracts con-
ducted on the program from 1958 through 1974:

MINERAL—RESOURCE AND MINERAL-FUELS INVESTIGATIONS 15

 

Per-
.mmw... my- 53.2: mg,”
it Tue 0
co t ta contracts tafzé
Silver _______________ 74 $5,505,000 41
Gold ________________ 64 3,145,000 24
Mercury _____________ 17 1,162,000 9
Copper ______________ 14 858,000 6
Lead-zinc ____________ 7 682,000 6
Lead-zinc-copper _____ 11 488.000 4
Molybdenum _________ 3 384,000 3
Iron ________________ 3 200,000 1
Beryllium ___________ 3 127,000 1
All others (cobalt,
fluorspar, mica,
nickel, platinum,
uranium) _________ 12 1 730,000 6
Total (15 com-
modities) ___ 208 $13,281,000 100

1 Revised.

MINERAL-RESOURCE EXPLORATION
TECHNOLOGY

Trace-element dispersion patterns, Coeur d'Alene district, Idaho

Some of the known mineral belts and associated
geochemical dispersion patterns in the Coeur d’Alene
district, Idaho, were founded by G. B. Gott and
J. B. Cathrall to be displaced as much as 24 km by
post-ore faulting. Through the use of map models
relating geochemical dispersion patterns to major
faults in the district, the approximate original posi-
tion and geometric relations of the mineral belts at
the time of emplacement of the ore deposits could
be determined. These maps revealed that dispersion
patterns of As, Cd, Pb, S. and Sb formed huge con-
centric aureoles around the original positions of
monzonite stocks and showed that the major north-
west-trending mineral belts were interrupted by
these aureoles. The aureoles probably were caused
by the heat from the monzonite intrusives during
an event that was independent of the formation of
the mineral belts.

The picture that emerged from this modeling by
geochemical and geologic maps indicated that about
90 percent of the ore that has been mined in the dis-
trict came from the area of the aureoles around the
stocks. Unexplored segments of these aureoles con-
stitute favorable ground for future prospecting.

Studies of alluvial materials from Alaska

Comparison of alluvial materials for use as geo-
chemical sample media.—In a study of minor ele-
ments in alluvial materials from the Candle and
Solomon quadrangles, Alaska, Sam Rosenblum and
T. G. Lovering compared the contents of Ag, Ba, Be,
Co, Cu, Ni, Pb, Sn, W, and Zn in 190 magnetic con-
centrates with those in 267 nonmagnetic concen-
trates and 274 conventional samples of alluvial silt.

 

The magnetic concentrates proved to be best in locat-
ing anomalies of barium, nickel, and zinc. The mag-
netic and nonmagnetic concentrates were about
equal in locating anomalies for beryllium and tin,
but the conventional samples of silt were not as ef-
fective. Nonmagnetic concentrates were better than
the other two media in identifying localities with
anomalous tungsten and were equal to the conven-
tional samples of silt in showing anomalous silver.
The conventional samples were more effective than
the other two media for locating anomalies of cobalt,
copper, and lead. Thus, as a group, the concentrates
appeared to be the more effective sample media for
7 of these 10 elements.

Contaminants in magnetic concentrates—Micro-
scopic examination by W. C. Overstreet of 680 mag-
netic concentrates from Alaska disclosed that detri-
tal magnetite was significantly interwoven with
other minerals or with particles of rock. These
grains from the subarctic contrasted strongly with
the nearly monomineralic detrital magnetite in
magnetic concentrates from the humid temperate
southeastern United States and the arid subtropics
of Saudi Arabia. In the humid temperate region,
mineral grains are disaggregated by chemical weath-
ering of the source rocks, and, in the arid subtropics,
the grains are separated by thermal shock under
extreme diurnal changes in temperature. If frost
action is an important factor in degrading rocks in
the subarctic, then frost action yields a much less
perfect separation of magnetite from other compo-
nents of the rocks than chemical weathering or ther-
mal shock. The result of this difference, so far as the
use of detrital magnetite as a sample medium for
geochemical exploration in the subarctic is con-
cerned, is that the abundances of the minor ele-
ments show greater dispersion, because of contam-
ination of the magnetite, than those of magnetites
from the humid temperate and arid subtropical cli-
matic zones.

Cyanogenic plants affect the geochemical cycle of gold

As a contribution to a study of the geochemistry
of gold (Shacklette, 1974) in the weathering cycle,
H. T. Shacklette measured the cyanide content of 151
species of plants (mostly trees and shrubs) occur-
ring in 12 vegetation types in Colorado, Nevada,
Arizona, and New Mexico. High cyanide concentra-
tions were found in 11 percent of the species an-
alyzed; 10 percent contained low concentrations of
cyanide; cyanide was not detected in 78 percent of
the species. Some cyanogenic species~were found in
all 12 vegetation-type areas, which occurred in habi-

16 GEOLOGICAL SURVEY RESEARCH 1975

tats ranging from alpine to desert. If these selected
species secrete cyanide to the extent known for some
other species, then large amounts (but probably low
concentrations) of cyanide are available to solubi-
lize gold in substrates near the plant roots.

Geochemical and isotopic zoning, Leadville district, Colorado

The zoning of ore deposits in the Leadville district
of Colorado, described by Loughlin and Behre
( 1934) ,was corroborated in part by J. C. Antweiler III,
W. L. Campbell, and E. L. Mosier, by studying varia-
tions in the composition of gold and galena and by
performing isotopic analyses of lead from galena.
Characteristically, when the distance from a center
of mineralization in the district increased, the con-
tent of silver in gold was found to increase, and the
number of other trace elements in the gold was
found to decrease. Galena near a center of mineral-
ization contained many trace elements, but, as the
distance away from the center increased, the
amounts of most elements in the galena decreased,
with the exception of magnesium, calcium, stron-
tium, and barium. Lead-isotope analyses showed
that lead from the galena becomes increasingly
radiogenic away from a center of mineralization.

Selective leaches enhance anomalies in areas of limonite

Representative samples of limonite—impregnated
quartzite, shale, sandstone, quartz latite porphyry,
and vein material were collected by A. V. Heyl from
an area near Pando in Eagle County, 0010., that is
characterized by replacement bodies of ferruginous
tungsten-bearing jasperoid in middle Paleozoic car-
bonate rocks. A portion of each sample was leached
by J. G. Viets with an oxylate solution to dissolve
the limonite, this method being similar to the one
developed by H. V. Alminas for the analysis of the
limonitic fraction of stream sediments. The dried
leachates and corresponding samples of ground
whole rock were then analyzed spectrographically by
E. L. Mosier. All samples of the ground Whole rock
in which tungsten was detected showed a strong in-
crease in the tungsten content of the leachate,
usually by at least a factor of 10. Other associated
indicator elements were similarly enriched in the
leachate, as the following data on a typical sample
of limonite-impregnated quartzite (table 1) illus-
trate.

The oxylate leach method thus appears to have
strong potential for enhancing geochemical anom-
alies.

TABLE 1.-—Coneentrations of selected elements in a whole-
roek sample and its leachate, Panda area, Eagle County,
Colorado .

[N, not detected at concentration shown in parentheses. L, detected but

in a concentration less than value shown in parentheses]

 

Whole

 

 

 

ac

Element ( 53:5) prple’e
300 20,000
100 7,000
1.5 15
5 200
30 300
20 700
70 1,500
N (5) 1 5
5 200
L ( 5 ) 200
N ( 10) 30
20 200

 

New instrument developed for detecting helium in soils

A portable helium detector developed by Irving
Friedman was installed in a four-wheel-drive vehicle
for field use. In-place measurements of helium in soil
gases were made by driving a steel probe 6 mm in
diameter 0.6 to 1.5 m deep into the soil. The measure-
ment took about 1 to 2 min and was precise to :50
ppb or about one-hundreth of the normal abundance
of helium in air. The instrument was used success-
fully to measure anomalously high values of helium
in soils above geothermal areas.

New method for analysis of antimony in geologic materials

An atomic-absorption method was developed by
E. P. Welsch and T. T. Chao for determining trace
amounts of antimony in geologic materials. The
method is rapid and free from common interferences
and has a sensitivity that is adequate for geochemi-
cal exploration. In this method, antimony in the
sample is first volatilized as SbI;,. The released anti-
mony is chelated and extracted by using trioctyl-
phosphine oxide and methyl isobutyl ketone and
then analyzed by atomic-absorption spectrophotom-
etry. For a set of 50 samples covering a wide range
of geologic materials, the correlation coeflicient be-
tween values for antimony obtained by the atomic-
absorption method and those obtained by the rhoda-
mine-B colorimetric method is 0.94. As many as 80
samples per man—day can be analyzed by the new
method.

New compilation of chemical methods useful in geochemical
exploration
A compilation of new and refined methods of trace
analysis useful in geochemical exploration was made
by F. N. Ward. Methods of chemical analysis useful
in geochemical prospecting for ore deposits are pre-

MINERAL-RESOURCE AND MINERAL-FUELS INVESTIGATIONS 17

sented along with limited repeatability data and
some examples of applications. Methods for Ag, As,
Bi, Cd, Co, Cu, F, Hg, Mo, Ni, Pb, Sb, Se, and Zn
are included. These elements were determined by
using molecular or atomic-absorption spectropho-
tometry, fluorescence, or chemical sensing of ion
activity. Thirty-eight trace elements occurring in
native gold were determined by semiquantitative
emission spectriscopy.

RESOURCE ANALYSIS

Resource data bases

Interest in the USGS Computerized Resource
Information Bank (CRIB) data base continued
throughout 1974, especially among outside organiza-
tions. In November, the Tennessee Valley Authority
(TVA) began accessing the CRIB file via its remote
terminal at Knoxville. Various types of arrange-
ments also have been made or are being discussed
with several other outside organizations. These de-
velopments helped to broaden the CRIB data-acqui-
sition system and user community. The Geologic Di—
vision is becoming a leader in the data processing of
mineral-resource information. In this connection,
the CRIB project staff has been called upon with in-
creasing frequency to provide guidance, training,
and orientation in data-base design and management
for scientists from a number of countries and or-
ganizations, including Peru, Bolivia, TVA, ERDA,
and the State Surveys of Idaho, Minnesota, Montana,
and South Dakota. During 1974, the CRIB file in-
creased to about 35,000 records. CRIB operations
became more effective following the implementation
of on-line ‘disk storage and the time-sharing mode of
operation (TSO).

Further development of the Geologic Retrieval
and Storage Program (GRASP) by R. W. Bowen
and J. M.. Botbol included interactive graphic dis-
play of the data accessed by the system. A new data
file was added to GRASP for the Branch of Coal Re—
sources by S. M. Cargill and A. C. Olson, namely,
USCOAL. This file contains a 16,000-record tonnage
inventory of coal resources, indexed by resource
categories (for example, depth, thickness, relia-
bility, and rank) and by area (state, county, town—
ship/range, and section). USCOAL is the first US
data file accessed by GRASP that is a daily produc-
tion environment; it is being used by the Branch of
Coal Resources to answer the many questions re-
ceived on US. coal resources.

 

Resource estimates

A preliminary estimate by C. S. Bromfield of the
lead-zinc potential in possibly concealed carbonate
replacement deposits of the Leadville-Oilman type
in the central portion of the Colorado mineral belt
suggested that ore containing 6 to 18 million tonnes
of lead and zinc remains to be discovered. In this
area, about 30 million tonnes of lead and zinc have
been recovered in 100 yr of mining from deposits of
this type discovered in outcrops of pre-Pennsyl-
vanian Paleozoic host rocks. The favorable host
rocks are exposed mainly in a narrow band along the
flanks of the principal mountain ranges in central
Colorado.

Elsewhere in the mineral belt, where these favor-
able host rocks are not absent through erosion or
nondep‘osition, they are concealed by younger rocks.
Speculative resources were estimated on the premise
that concealed host rocks are potentially as produc-
tive as exposed and maturely prospected rocks.

K. C. Watts, Jr., E. L. Mosier, and H. V. Alminas
found that base-metal anomalies, delineated in areas
covered by thick Tertiary volcanic sequences in
southwestern New Mexico, on the basis of spectro-
graphic analyses of oxalic acid leachates of rock,
soil, and stream sediment samples, appear to give
evidence of blind postvolcanic mineralization. These
presumed leakage halos show a close relationship to
major structural and aeromagnetic features within
this area.

Mineral resources are known in all the major geo-
graphic subdivisions of Alaska and, along with that
geology of these mineral resources and the surround-
ing areas, have been described in reports and maps
prepared by Federal and State agencies. These re-
ports and maps have been indexed by 1 :250,000 top-
ographic quadrangles and the resulting reference
lists released to open files (E. H. Cobb, 197 4a—h) .

Resource model studies

Analysis by D. A. Singer, D. P. Cox, and L. J.
Drew (1975) of the average grades and total ton-
nages of porphyry, stratabound, and massive sulfide
copper deposits has shown that tonnages and grades
are approximately lognormally distributed; this dis-
tribution makes it possible to predict the probability
of various grade-tonnage classes for a resource esti-
mate. In addition, the discovery that grades are in-
dependent of tonnages for porphyry copper deposits
suggests that very large tonnage, low-grade deposits
are just as rare as very large tonnage, high-grade
deposits.

18 GEOLOGICAL SURVEY RESEARCH 1975

The exploration play mechanism was found by L.
J. Drew (1975) to be the fundamental unit by which
petroleum resources are converted into reserves. A
two-stage regression model of the exploration proc—
ess was constructed in which the wildcat drilling
rate and the deposit discovery rate are explained in
terms of a suite of economic and physical variables.
Several important conclusions were reached when
this model was used to analyze the exploration his-
tory of the Powder River Basin, Wyo.: (1) the rate
at which wildcat wells were drilled is highly cor-
related with the discovery expectations of the ex-
ploration operators; (2) the number of deposits dis-
covered is highly correlated (nonlinear) with the
wildcat drilling rate; (3) the aggregate volume of
petroleum discovery is independent of the wildcat
drilling rate; (4) a learning effect was found to oc-
cur within an exploration play; and (5) the rate at
which deposits were discovered is independent of the
level of physical exhaustion of the basin. For the
most part, these results are a direct consequence of
the manner in which the exploration play mechanism
operates.

A comprehensive data storage and retrieval sys-
tem for the DEC 10 System was designed by J. K.
Pitman to estimate oil yield, thickness, and resources
on the basis of oil-shale Fischer assay and saline
mineral data for core holes in Colorado, Utah, and
Wyoming. These estimates have provided the basic
data for evaluating lands involved in exchanges be-
tween the Federal Government and private industry,
as well as for determining areas suitable for in-place
or underground recovery methods.

Mineral resources and geology of South Dakota

A comprehensive report entitled “Mineral and
Water Resources of South Dakota” was published in
1975 by the US. Senate Committee on Interior and
Insular Affairs and as a bulletin of the South Dakota
Geological Survey. This report is a greatly revised
edition of a similar volume issued in 1964. Senator
George McGovern requested that the USGS be the
lead agency in preparing the new edition; other con-
tributing organizations were the South Dakota Geo-
logical Survey, the South Dakota School of Mines
and Technology, the US. Bureau of Reclamation,
and the US. Bureau of Mines. J. J. Norton was edi-
tor of the mineral-resource and geologic sections of
the report.

Flat-lying sedimentary rocks are at or near the
surface over most of the State. In the west, however,
the most striking feature is the Black Hills, a domal
uplift with Precambrian rocks exposed in its core

 

and a belt of Tertiary intrusions crossing its north-
ern end. East and northeast of the Black Hills is a
thick lens of sedimentary rocks constituting the
southern part of the Williston Basin. Other aspects
of the subsurface geology across the State are less
pronounced. Precambrian rocks reappear at the sur-
face in the southeast and northeast. The drainage
system of the region is dominated by the Missouri
River, which bisects the State. East of the river,
much of the surface has a cover of glacial deposits.

The Black Hills have the chief mineral deposits,
mainly because their Precambrian rocks are the
source of the gold that has furnished more than half
of the nearly $2 billion mineral output of the State.
The several pegmatite minerals (feldspar, mica,
lithium minerals, beryl, and tantalite—columbite), as
well as decorative stone and mineral specimens,
have also been important,“ and monite iron will
ultimately become a significant contributor to the
economy. Sedimentary rocks on the flanks of the
Black Hills have gold-silver, lead-silver, and tung-
sten deposits and also bentonite, other clays, ura-
nium, and gypsum. South Dakota is unique in having
a State-owned cement plant, Which is located in
Rapid City on the eastern side of the Black Hills and
draws its raw materials from nearby. Oil output
from the South Dakota segment of the Williston
Basin is small but rapidly increasing. Lignitic coal
is abundant in the northwestern part of the State,
although none is being mined now. Granite dimen-
sion stone is the basis for a small but significant in-
dustry near the northeastern border of the State.
Production of sand, gravel, and crushed stone is, as
in all States, an important industry.

The report treats each resource in some detail and
covers, as well, all aspects of the geology that bear
on exploration and development. Chapters on geo-
physics and geochemistry show that these fields may
have much more to offer in South Dakota than they
have yielded thus far. Examination of the environ-
mental effects of resource development indicates
that damage has been spotty and can in the future
be eliminated or brought within reasonable limits.
In addition to its other uses, the volume serves as a
guidebook to the geology of South Dakota.

Many maps show the geology and the distribution
of resources. One of the maps is a new attempt to
organize the Precambrian rocks of the Black Hills
into a plausible stratigraphic and structural ar-
rangement. This map should facilitate exploration
for gold because it indicates where rocks of the kind
containing gold deposits (especially the famous
Homestake deposit) are likely to be found in the

MINERAL-RESOURCE AND MINERAL-FUELS INVESTIGATIONS 19

subsurface. Another map shows the locations of all
the oil tests ever drilled in the State.

Gold almost certainly will continue as South Da-
kota’s most important mineral product. The outlook
for finding new deposits is especially favorable. The
authors of the report indicate that other commodi-
ties also show promise. The ones that most deserve
increased attention are iron, oil, coal, uranium, lead-
silver, decorative stone, molybdenum, and zeolites.

COAL RESOURCES

U.S. coal resource estimate increased 23 percent

According to a recent compilation by Paul Averitt
(1975) , the revised estimates of U.S. coal resources
remaining in the ground as of January 1, 1974, total
3,600 billion tonnes. This huge tonnage constitutes
about one-fifth of the total world supply. The revised
figure is 23 percent more than previous recent esti-
mates; the increase is based on geologic mapping,
exploration, and study conducted during the last few
years by Federal and State governmental agencies
and by private'indu-stry. Resources of 1,570 billion
tonnes have been identified by mapping and explora-
tion, and an additional 2,030 billion tonnes, classed

as hypothetical, are estimated to be present in un—'

mapped and unexplored areas and in the deeper
parts of known coal basins.

Uranium in coal of the northern Great Plains

V. E. Swanson reported that the possibility of re
covering uranium as a byproduct of coal combus-
tion and the apprehension of environmental con-
tamination by radioactive products in the vicinity
of coal-fired electrical generating plants have in-
spired a renewed widespread interest in the uranium
concentration in coal of the northern Great Plains.
Approximately 250 samples of subbituminous coal
and lignite were chemically analyzed for 43 elements
as a part of the Department of Interior’s Northern
Great Plains Resource Program (V. E. Swanson,
Claude Huffman, Jr., and J. C. Hamilton, 1974; U.S.
Geological Survey and Montana Bureau of Mines
and Geology, 1974). The samples represented coal
from all of the 15 major operating mines in the re-
gion and from 40 cores in areas proposes to be mined
in the future. Uranium contents of the 250 coal sam-
ples were determined by H. T. Millard, J r., using the
delayed neutron activation method. The following
data compiled from the analyses may dispel concern:

1. The mean uranium content of the coal is 0.9 ppm;
the range is 0.1 to 7.5 ppm U.

 

2. The average uranium content of coal shipped
from eight major lignite mines in western
North Dakota and eastern Montana is 1.0 ppm,
and from individual mines it ranges from 0.8
to 1.2 ppm. The average uranium content of
coal shipped from the seven major subbitumi-
nous mines in the Powder River Basin is 0.8
ppm, and from individual mines it ranges from
0.4 to 1.1 ppm.

3. Uranium is nonreactive and nonvolatile at the
temperatures of powerplant combustion, so
the element is concentrated in the ash, a fact
supported by analyses of bottom- and fly-ash
samples from power plants. If, for example, a
coal contains 1.0 ppm U and 10 percent ash,
the powerplant ash contains 10 ppm N.

Coal in the Powder River Basin in Wyoming and Montana

A study by N. M. Denson, W. R. Keefer, and J. H.
Dover revealed that the low-sulfur subbituminous
coal beds extending over a wide area in the Powder
River Basin in“ Wyoming constitute one of the
world’s largest known coal deposits and are prime
targets for future mining. One prominent bed, the
Wyodak-Anderson coal, ranges from 15 to 30 m in
thickness and lies at depths of less than 61 m in a
strip 130 km long and 3 to 5 km Wide (approxi-
mately 75,000 ha) (Densbn and Keefer, 1974; Den-
son, 1975). The bed contains approximately 13 billion
tonnes of coal in the tract that lies 61 m or less below
the surface. Available analyses of the coal indicate
averages of less than 1 percent S and 6.3 percent ash
and a heat value of 21 million J /kg. The study is
based on sonic-density, gamma—ray, and electric logs
from numerous oil and gas tests and from recent coal
drill-hole data compiled by the Montana Bureau of
Mines and Geology.

A preliminary evaluation of the distribution of
coal beds in the Recluse mine site model area in
northern Campbell County, Wyo., was made from
340 geophysical well logs by R. G. Hobbs, E. R.
Landis, A. R. Norton, and J. D. Sanchez. Seven per-
sistent, named coal beds were traced in the Tongue
River Member of the Fort Union Formation of
Paleocene age in a rectangular area of four 71/2-min
quadrangles. A drill program is underway to obtain
core samples that will be analyzed to determine the
quality and composition of the coal and the charac-
teristics of the intervening rocks. These geologic and
geochemical data and additional resource, geophysi-
cal, and hydrological information will be used to de—
termine the critical, geologically related parameters

20 GEOLOGICAL SURVEY RESEARCH 1975

necessary for the development of the natural re-
sources in the model area.

Lignite resources, Denver basin

P. E. Soister (1974) estimated that between 9 and
18 billion tonnes of lignite underlie part of the Den-
ver basin in an area approximately 48 km wide and
120 km long from near Denver to south of Ramah
and Calhan, Colo. Three lignite beds present in most
of the area range from 3 to 16.6 m in thickness 10-
cally and average between 3 and 8 m thick region-
ally.

Coal beds related to tectonics in Utah

Detailed stratigraphic studies by Fred Peterson
(1969) in Kane County, southern Utah, indicated
that the subsidence of the Kaiparowits structural
basin and the development of three northwest-trend-
ing anticlines within the basin significantly influ-
enced the distribution and thickness of commercially
valuable coal deposits in the Upper Cretaceous
Straight Cliffs Formation. Regionally, most of the
coal beds thicken northwestward toward the deeper
part of the Kaiparowits basin. Locally, the coal beds
thin over the crests of the ancestral Nipple Bench,
Smoky Mountain, and Rees Canyon-Rock Creek an-
ticlines. The areas of thinner coal demonstrate that
continued or recurrent movement immediately pre-
ceding the classic Laramide orogeny occured on
these structural features during middle Turonian-
early Campanian time. If areas of active growth of
structural features during deposition are properly
identified and evaluated with respect to the local
structural setting, clastic sediment sources, and
shoreline trends, knowledge of them may prove val-
uable for coal exploration, development, and re-
source evaluation in other parts of the Colorado
Plateau.

Deformed coal in the Bering River coalfield. Alaska

Thick coal is spectacularly exposed locally in the
Bering River coalfield in Alaska. The coal beds ap-
pear to change thickness abruptly; the extent and
continuity of individual beds are difficult to deter-
mine because of the complex structure of the coal-
bearing strata. According to recent studies by R. B.
Sanders, the coal was found in boudinlike pinches
and swells along the limbs of folds, along fault
planes, and especially in dilations along the axes of
What appears to be a series of faulted chevron folds.
The coal ranges in rank from low volatile bitumi-
nous to semianthracite, has a low sulfur content, and
is, in part, of coking quality. The highest rank coal

 

is found in apparently more continuous beds located
within the easternmost part of the coalfield, where
structure appears to be less complex.

Supplemental bibliography and index of coal-related

publications

A bibliography and index of about 200 coal-re-
lated reports and maps published by the USGS dur-
ing the 31/2-yr period January 1971 through June
1974 were compiled by F. K. Walker (1975). The
listings are supplemental to those in USGS Bulletin
1377 (Averitt and Lopez, 1972) . Most of the publica-
tions cited may be consulted in large public libraries
and in most college and university libraries; some
that are not yet out of print can be ordered from the
USGS.

OIL AND GAS RESOURCES

Possible petroleum accumulations in Baltimore Canyon Trough
area, offshore Atlantic Ocean

In the mid-Atlantic area (Baltimore Canyon
Trough area), Lower Cretaceous rocks, which prob-
ably contain ( 1) marine sandstones associated with
deltaic sequences and (2) terrigenous sediments in-
terfingering with carbonates, are prospective petro-
leum targets (W. J. Perry, Jr., and others, 1974).
These Lower Cretaceous sediments extend from
about 1,500 m below the water bottom to 6,100 m
along the axis of the Baltimore Canyon Trough. Ac-
cording to R. Q. Foote, trapping mechanisms for
petroleum on the shelf in the Baltimore Canyon
Trough area are expected to fall into four cate-
gories: (1) relief over piercement structures (ig-
neous intrusions and salt domes), fault blocks, and
possible reefs; (2) possible reefs; (3) stratigraphic
traps; and (4) closure against faults.

The preliminary results of a seismic survey indi-
cate that a Cretaceous reef structure may underlie
the Continental Slope in the Baltimore Canyon
Trough area (R. E. Mattick, unpub. data, 1975).
Petroleum may have migrated from potential source
beds beneath the slope and rise and been entrapped
in the reef (E. C. Rhodehamel, unpub. data, 1975).
This structure, even though it is in water depths of
1,200 m, could prove to be a significant petroleum
trap.

Revised petroleum data for the Appalachian basin

The area of the Appalachian basin, which is of
interest to the petroleum geologist, lies between the
crest of the Cincinnati arch extended on the west
and the western edge of the Blue Ridge anticlinor-
ium, the Reading Prong, and the Hudson Highlands

MINERAL-RESOURCE AND MINERAL-FUELS INVESTIGATIONS 21

on the east; the southern side of the Adirondack
Mountains or the Canadian border on the north;
and the northern edge of the overlapping Gulf Coast
Cretaceous rocks to the south in Alabama. Accord-
ing to Wallace de Witt, Jr., the basin cover-s about
540,450 km2 and is subdivided along the Allegheny
front into the larger, western, generally petrolifer-
ous Appalachian Plateaus, covering 424,300 kmz,
‘ and the eastern, smaller, generally petroliferous,
structurally complex Valley and Ridge, province,
covering 116,000 kmz. V

To date, more than 2.5X109 bbl of oil have been
produced in the basin, almost all from rocks under-
lying the Appalachian Plateaus. More than half of
this volume, 1.7X109 bbl, came from strata of De-
vonian age, and more than 75 percent occurred in
‘quartzose elastic reservoir rocks. Remaining re-
serves producible by existing methods amount to
about 3.0X103 bbl. In contrast, sparse data suggest
that the volume of currently nonproducible oil re-
maining in reservoir rocks of the Appalachian basin
ranges from 8><1010 to 12><101° bbl. Producing any
quantity of this oil will require extensive drilling in
the relatively untested parts of the basin, including
the eastern half of Lake Erie, as well as the develop-
ment of new and imaginative techniques for im-
proved recovery in areas of oil production, which
may or may not have been partly enhanced by sec-
ondary recovery methods in addition to the original
period of primary production.

Paleogeographic reconstruction—a method for estimating

crustal shortening in the southern Valley and Ridge

province of the Appalachian basin

L. D. Harris found that integration of regional
stratigraphic data from many surface sections of the
Nolichucky Shale in several fault slices northwest of
the Saltville thrust outlines a lobate algal stromato-
lite bank in this Late Cambrian formation. Because
the algal bank has limited geographic extent, both
edges could be identified from northwest to south-
east in the Pine Mountain, Wallen Valley, Clinch-
port, and Copper Creek fault belts. The faults tran-
sect the algal bank at a wide angle, which juxtaposes
bank and nonbank facies of the Nolichucky across
the thrust.

Paleogeographic reconstruction of the bank from
facies data in the several fault slices gave a reason-
able configuration for the bank before thrusting. By
fitting individual thrust slices into their proper geo-
metric position in the original bank, on the basis of
the shape and extent of the segment of the bank
. within each fault slice, the amount of movement on

 

the Pine Mountain, Wallen Valley, Clinchport, and
Copper Creek thrusts can be estimated as approxi-
mately 64 km.

Although these data apply only to the western half
of the Valley and Ridge province, they suggest that
a similar or greater amount of shortening may have
occurred between the Saltville thrust and the west-
ern edge of the Blue Ridge thrust.

Although this method for estimating crustal short-
ening requires an abundance of good stratigraphic
data and the presence of well-defined identifiable
facies in several thrust slices, it may be readily
applicable in other parts of the Valley and Ridge or
in tectbnically similar areas such as the Foothills
belt of western Canada.

Pennsylvanian sedimentation, Carbon, Sweetwater, and

Fremont Counties, Wyoming

Detailed examination and description of rocks and
bed forms in cores drilled in the Lost Soldier and
Wertz oil fields, south-central Wyoming, by M. W.
Reynolds, T. S. Ahlbrandt, J. E. Fox, and P. W.
Lambert (unpub. data, 1975) demonstrated that the
Pennsylvanian Tensleep Sandstone was deposited in
an interfingering succession of shoreface, foreshore,
and eolian dune and interdune environments. The
shoreline fluctuated across an 8-km belt between the
oil fields, so that Tensleep strata at Lost Soldier oil
field on the west are of mixed shoreface and fore-
shore facies, whereas the strata at Wertz oil field on '
the east are dominantly of foreshore and eolian
origin. Only during deposition of the upper part of
the Tensleep did eolian deposits regress westward
across the area of the Lost Soldier field. The dis-
tribution of oil, cementation, and fractures in the
facies support the existing interpretation that oil
accumulation in the Lost Soldier field was controlled
late by fractures, whereas the control of accumula-
tion in the Wertz field resulted from a combination
of facies and cementation, the fracturing playing a
less important role than it did at Lost Soldier.

Continental sedimentation and hydrocarbons in Tertiary rocks,
northeastern Utah
More than 750 million barrels of measured, indi-
cated, and inferred oil reserves have been discovered
in stratigraphic traps in marginal and open lacu-

- strine facies of the Green River Formation. Delta-

front, distributary channel, and overbank sandstones
are the primary reservoir units. Overpressured res-
ervoirs are found in the lower part of the Green
River Formation above the Colton Formation and
in the Flagstaff Member of the Green River Forma-

22 GEOLOGICAL SURVEY RESEARCH 1975

tion; these reservoirs are at depths generally below
3,000 m west of the Green River, Where lacustrine
rocks abruptly change facies laterally to the rela-
tively impermeable alluvial and open lacustrine
facies that serve as part of the trap mechanism,
according to T. D. Fouch, 1975a. Nonassociated gas
is produced from stratigraphic traps in marginal
lacustrine rocks of the Green River Formation and
from traps Within the paludal-alluvial facies of the
North Horn Formation and the Wasatch Formation.
Channel sandstones and associated overbank sand-
stones serve as reservoirs for gas in nonlacustrine
rocks. Fouch (1975b) has found that traps are re-
lated to the following: (1) change in clay content
of the sandstone within a single channel, (2) change
from one genetic sandstone type to another, and (3)
regional facies changes. Excellent potential remains
for stratigraphically trapped gas.

Petroleum source-rock studies, Permian System

E. K. Maughan has found that the organic-rich
Meade Peak and Retort Phosphatic Shale Members
of the Permian Phosphoria Formation in western
Wyoming and adjacent parts of Utah, Idaho, and
Montana are probable source beds of the oil and gas
found in upper Paleozoic rocks of the region. The
Meade Peak and Retort contain as much as 8.8 per-
cent residual organic carbon. Some thin beds in the
Meade Peak and Retort contain as much as 30.7 and
21.4 percent organic carbon, respectively.

The Meade Peak occupies an area of approxi-
mately 115,000 km2 and has a maximum thickness of
about 50 m in eastern Idaho and northern Utah. The
Retort occupies an area of approximately 100,000
km? and has a maximum thickness of about 35 m
in southwestern Montana and in central western
Wyoming. Volumetrically, the Meade Peak com-
prises about 2,025 km3 and the Retort about 1,225
km3 of sediment.

The Phosphoria Formation was deposited along
the Continental Shelf east of the late Paleozoic
mobile belt. Subsequently, at least 2 km of overlying
sediment was deposited by the end of the Triassic
in the western part of the region and, because of
slower rates of deposition, by the end of the Cre-
taceous in the eastern part of the region. This depth
of burial probably produced adequate pressure and
temperature for generation of hydrocarbons from
the organic substances.

An attempt was made to exploit the Retort as an
oil shale near Dillon in southwestern Montana,
where it yielded an average of 84 l of oil per tonne.
Elsewhere, Fischer oil assays yielded little or no

 

petroleum from the Retort ; the Meade Peak, where
it has been tested, seems to be below detectable
limits.

Organic-rich Devonian eugeosynclinal rocks in north-central

Nevada

F. G. Poole found that the allochthonous Devonian
Woodrufl" Formation in the Pinon Range, south-
western Eiko County, Nev., locally contains as much
as 17 percent organic carbon and yields as much as
5,200 ppm soluble hydrocarbons. The Woodruff,
which consists principally of dark-colored marine

.chert, mudstone, siltstone, minor sandstone, and

limestone and dolomite, is believed to have been
deposited in a Devonian .marginal ocean basin west
of the continental edge and east of an offshore
island arc. The eugeosynclinal Woodruff deposits
were subsequently deformed and obducted eastward
onto the Outer Continental Shelf as part of the
Roberts Mountains allochthon during the Late De-
vonian and Mississippian Antler orogeny. Palyno-
morph and conodont alteration colors indicate a
postdepositional history of persistent low tempera-
tures that probably never exceeded 100°C, and it
seems possible that organic matter in the Woodrufi'
could have generated petroleum in the late Paleo-
zoic. Similar Paleozoic eugeosynclinal rocks in the
Western Uni-ted States should be examined and
evaluated for their petroleum potential.

Petroleum source beds in the Pilot Shale of the eastern

Great Basin

The Upper Devonian (lower Famennian) lower
unit of the Pilot Shale .has been found to contain
dark-gray mudstone and. limestone beds of sufficient
thickness, areal distribution, and organic richness
to merit consideration as source beds for petroleum
generation, according to C. A. Sandberg and F. G.
Poole. The interval of lower Famennian source beds,
which lies between the Lower Palmatolepis crem’da
and Lower P. marfinifem conodont zones, is 93 m
thick, has an average organic carbon content of 2.2
percent, and yields about 160 ppm total soluble hy-
drocarbons in the Confusion Range, Utah. The lower
unit of the Pilot was deposited on a miogeosynclinal
carbonate shelf in a rapidly subsiding basin cen:
tered in White Pine County, eastern Nevada, and
adjacent Millard County, Utah. Alteration colors of
contained conodonts indicate that these source bed-s
Were never subjected to temperatures in excess of
90°C in Utah and 140°C in Nevada. These beds may
have generated and expelled petroleum for distant
eastward migration into the western Rocky Moun-

MINERAL-RESOURCE AND MINERAL-FUELS INVESTIGATIONS 23

tains region as well as for local accumulations within
adjacent formations in western Utah.

Neogene stratigraphy and structure, California continental
borderland

Bedrock samples collected along geophysical tra-
verses on the California continental borderland show
that Neogene strata constitute most of the exposed
bedrock south of the northern group of Channel
Islands and west of the mainland shelf. Preliminary
study of these rocks by J. G. Vedder, L. A. Beyer,
Arne Junger, G. W. Moore, A. E. Roberts, J. C.
Taylor, and H. C. Wagner (1974) indicated that
they are composed primarily of hemipelagic calcare-
ous claystone with subordinate amounts of volcanm
genic and terrigenous detritus at places. Microfossil
assemblages identified and correlated by R. E. Arnal
and J. D. Bukry show that most of Miocene time is
represented by truncated stratal sequences along the
crest of Santa Rosa-Cortes Ridge. Miocene volcanic
rocks are concentrated on the compound-ridge sys-
tem that connects Santa Cruz Island, San Clemente
Island, and Santa Catalina Islands and that extends
southeastward to Fortymile Bank. These volcanic
rocks range in composition from rhyodacitic to
basalt; " it are chiefly andesitic. Thick sequences of
Pliocene frata (>400 m) are restricted to topo-
graphic basins except for local areas on and near
the mainland shelf.

In general, major structures inferred from geo-
physical surveys trend northwest throughout the
borderland south of the northern island group. One
exception is the east-trending fault zone that forms
the northern edge of the San Nicolas basin. Normal,
reverse, and strike-slip separations are inferred on
faults that range in age from Miocene to Holocene.
Large folds in the outer ridges and basins are
nearly symmetrical and have low amplitudes and
broad wavelengths, in contrast to those along the
mainland coast. Possibly early Miocene, late Mio-
cene, and Pliocene unconformities of local extent
are recognized on acoustic-reflection records, which
were interpreted by J unger and Wagner.

Development of substantial structural relief is
suggested by the presence of locally derived clastic
detritus in some early and middle Miocene strata.
The restriction of thick Pliocene sequences to basins
implies the existence of a well-defined basin and
ridge topography by that time.

Some of the shaly units that range in age from
early Miocene to early Pliocene contain suflicient
organic matter to generate fluid hydrocarbons if
their deformational and thermal histories have been

 

appropriate. Structures suitable for large accumula-
tions of petroleum are commonplace; but, until these
structures are tested for their reservoir character-
istics, resource appraisals will remain conjectural.

Measured sections of West Foreland and Tyonek Formations,

Kenai Peninsula Borough, south-central Alaska

Exposure of Tertiary rocks on the northwestern
flank of the Cook Inlet basin near Capps Glacier
and along Chuitna River were measured, described,
and sampled in detail for heavy-mineral and paly-
nological studies by W. L. Adkison, J. S. Kelley, J r.,
and K. R. Newman (1975). The rocks are assigned
to the West Foreland and Tyonek Formations. The
West Foreland, possibly of Eocene age, consists of
a conglomerate 366 m thick and lies unconformably
on Mesozoic rocks. In the basin to the southeast, the
Hemlock Conglomerate overlies the West Foreland
and is the most important oil reservoir in the area.
At the exposure near Capps Glacier, the Hemlock is
missing because of erosion or nondeposition. This
conclusion is based on the palynological determina-
tions by NeWman and on a heavy-minerals study
by Kelley (unpub. data, 1975). The Tyonek Forma-
tion, which unconformably overlies the West Fore—
land, consists of conglomerate and sandstone in the
lower part and sandstone, siltstone, and coal in the
remainder. The total thickness exceeds 671 m. Strat-
igraphic relationships between four measured sec-
tions were only partly determined because of major
faulting or the lack of exposures in large areas.
These measured sections provide valuable surface
control for subsurface stratigraphic units that pro-
duce oil and gas in the Cook Inlet Tertiary basin.

Energy resources of the Earth

M. K. Hubbert (1972) described the Earth’s en-
ergy resources as consisting of three continuous
energy fluxes and of certain stores of energy beneath
the Earth’s surface. The continuous energy fluxes
are: (1) solar radiation at a rate of 174,000X1O12
thermal watts; (2) geothermal energy, 32X1012 W;
and (3) tidal energy, 3X10” W. The stores of en-
ergy within an accessible depth of about 10 km
beneath the Earth’s surface consist of thermal en-
ergy, the chemical energy of the fossil fuels, and
nuclear energy.

During the last million years, the human species
has risen to a position of dominance among the
world’s animals by progressively developing means
for controlling ever-larger-amounts of these energy
resources, particularly the fossil fuels. This control
has made possible the rise of the present industrial

24 GEOLOGICAL SURVEY RESEARCH 1975

civilization; it has also created one of the most
drastic ecological disturbances of the Earth’s plant
and animal populations ever known. Most of this
disturbance has occurred during the last century,
and it is estimated that the bulk of the world’s oil
will be consumed within the next 60 yr, and the
bulk of all kinds of fossil fuels Within the next 3
centuries. For the United States, the peaks in the
production of both oil and gas have already been
passed, and most of the remaining 'oil and gas will
be consumed by the end of the present century.
Ultimately, if such a civilization is to survive, it
must be based upon a sustained energy source of an
appropriate magnitude. The most likely choice for
this source eventually will be the energy from solar
radiation.

Oil reserves of deep basins

Investigations by L. C. Price and M. A. Ratclifl‘,
Jr., provided evidence of a hot, deep origin and
migration of crude oil. Areas of investigation include
the organic geochemistry of shales and crude oils
and the geology of oil occurrence. One study shows
that oil gravity correlates more strongly with the
salinity of associated waters than with depth and
thus suggests that changes occurring in reservoired
crude oils with increased depth are due to crude-oil
degradation and not to thermal cracking. Thus, we
might expect to encounter reservoired crude oil at
depths much greater than those predicted by more
conventional hypotheses. Detailed examination of
oil occurrence in many different basins has shown
that the oil occurs precisely where it should if it is
moving up from the deep basins along faults. Thus,
this model offers a powerful new oil-exploration
tool. Geochemical-geologic evidence also shows that
we may expect large reserves of dissolved crude oil
in deep-formation waters of some sedimentary
basins.

Organic matter and hydrocarbons in barrier island quartzose

sands

Field and laboratory studies by J. G. Palacas,
P. M. Gerrild, A. H. Love, and A. A'. Roberts of three
quartzose sand facies of barrier islands extending
from Pascagoula, Miss., to Tarpon Springs, Fla.,
showed that the relative amount of organic con-
stituents is as follows: pond facies>lagoon facies>
marine facies. In the same order, average organic
carbon contents were about 0.3, 0.1, and 0.05 per-
cent, and hydrocarbon contents were 10, 3, and 1.5
ppm. Gas chromatographic data and quantitative
parameters indicated that the hydrocarbons were

 

derived from aquatic and terrestrial organisms and
were not due to oil pollution. Hence, the hydrocar-
bon contents in these sands are considered as base-
line concentrations. With regard to later diagenesis
and the origin of petroleum, if approximately 5
percent of the organic matter were thermally con-
verted to petroleum at depth, then 50 to 300 ppm
of hydrocarbons could be generated in these rela-
tively clean sands. These amounts of hydrocarbons
in sand would then represent a potential source for
ready migration and accumulation of petroleum.

Origins of natural gases in Montana

Three basic types of natural gas in Montana have
been identified by D. D. Rice (1975): (1) gas of
biogenic origin (immature) ; (2) gas occurring With
oil, designated associated gas (mature); and (3)
high-temperature gas (postmature). Most Montana
gas is biogenic, generated from predominantly ma-

rine organic source material. Biogenic gases are

produced near the surface and to depths of 800 m
by anaerobic bacteria. This gas is characterized by
a high methane (CH) content (>90 percent) and
by enrichment in the light C12 isotope (8013, —60
permill). As depth and (or) temperature increase,
thermal metamorphism predominates, and associ-
ated gas is formed. This gas has a higher content
of heavier hydrocarbons and a greater 013/012
ratio (8013, —55 to —45 permill). In some areas
surrounding the Bearpaw Mountains and Sweet
Grass Hills, which were sites of Tertiary igneous
activity, high-temperature gas was generated. This
gas is distinguished by a further increase in the
013/012 ratio (8013, —40 permill) and high methane
content. Some biogenic gases have been altered by
thermal metamorphism to form gases of mixed
origin.

The identification of gas types by origin, When
combined With an analysis of all geologic factors,
is an invaluable aid to the exploration geologist. He
can identify new areas for exploration, predict the
type of accumulation that should occur, and estimate
reserves.

Possible petroleum prospect located in Denver basin

A possible petroleum-related geochemical anomaly
in surface rocks in the Denver basin near Boulder,
0010., was identified during the summer and fall of
1974. The chance discovery resulted when T. J.
Donovan and R. L. Noble (1975) were developing
aerial reconnaissance and mapping techniques using
light aircraft as an observation platform. The geo-
chemical anomaly is halo shaped and suggests a

MINERAL-RESOURCE AND MINERAL—FUELS INVESTIGATIONS 25

prospective area of about 20 ka. Regional sub-
surface data support the possibility of a buried de-
posit in Cretaceous sandstone reservoirs.

Portable helium detector for energy resource exploration

Preliminary work by A. A. Roberts, Irving Fried-
man, T. J. Donovan, and E. H. Denton (1975) indi-
cated that a helium-survey technique may be ap-
plicable as an exploration tool for geothermal
resource areas, as well as for petroleum and natural—
gas deposits. Using a portable mass-spectrometer-
type leak detector, they were able to show anomal-
ously high helium concentrations in soil gases near
hot springs and other abnormally warm areas. In
contrast, the soil gases near cold regions have con-
tained only the normal background level of helium.
Further preliminary work suggests anomalous hel-
ium concentrations in soil gases over petroleum
deposits.

Manganese as a petrolum pathfinder element

T. J. Donovan, R. L. Noble, Irving Friedman, and
J. D. Gleason (1975) showed that manganese con-
centrations in the carbonate lattices of surface—
cemented rocks overlying petroleum deposits vary
in a systematic and mappable way that appears to
reflect the subsurface distribution of petroleum. The
concentrations typically range through one or two
orders of magnitude and have been found over
known and suspected oil deposits. Both anomalous
apical and aureole patterns over anticlinal traps
haVe been documented. The preliminary data sug-
gest that manganese may be a suitable petroleum
pathfinder element for geochemical-exploration pro—
grams.

Summary of factors controlling porosity distribution

J. E. Fox, P. W. Lambert, R. F. Mast, N. W. Nuss,
and R. D. Rein have found that a general critical
depth appears to be controlling the degree of poros-
ity. At depths less than approximately 3,050 m in
the Bighorn and Wind River Basins, Wyo., and less
than approximately 2,440 m in the greater Green
River Basin, Wyo., the porosity of the Tensleep is
highly variable and ranges from 2 to 26 percent and
2 to 12 percent, respectively. Petrographic indica-
tions are that several types of cements control the
porosity at these shallower depths. These cementing
agents include calcite, dolomite, anhydrite, and sec-
ondary silica. At depths greater than approximately
3,050 m and 2,440 m, the variability of porosity is
less, ranging frOm 2 to 6 percent. At these greater
depths, dominantly quartz overgrowths and sec-

 

ondary silica cement fill the pore spaces. These prob—
ably reflect the influence of greater pressure on the
more deeply buried aren-aceous sandstone. The de-
gree of porosity can be predicted more easily below
the critical depth than it can be at shallower depths,
where it is more variable.

Applications of chalk diagenesis to petroleum-exploration

problems

Petrographic, scanning-electron-microscopic, and
oxygen-isotopic analyses of chalk samples from 22
wells in the North Sea area, plus Deep Sea Drilling
Project (J OIDES) cores and outcrop samples from
England and Ireland, indicated to P. A. Scholle
that an orderly sequence of diagenetic changes oc-
curs with progressively ‘deeper burial. Burial is
accompanied by loss of porosity (hardening) due to
redistribution of carbonate by pressure solution. The
reprecipitated carbonate forms mainly as over-
growths on\ coccolith plates and as fillings of foram
chambers. At the same time, progressive recrystalli-
zation leads to alteration of the bulk-oxygen-isotopic
values of chalks. As a result , these isotopic values can

- be used to determine maximum depth of burial of

chalks (and their associated section), paleogeother-
mal gradients, and proximity to zones of deforma-
tion. The termination of further diagenesis by oil
entry into the chalks can be used to date the time
of oil migration into the reservoir. Chalks contain-
ing oil have anomalously high porosity and unusu-
ally slight recrystallization for their depth of burial,
indicating that the presence of oil may have helped
retain favorable reservoir characteristics.

Isotopic analysis can be used with full cores, side‘
wall cores, or cuttings, and, unlike most organic
geochemical methods, it does not require special
sample handling. Application of this technique al-
lows the regional mapping of paleogeothermal pat-
terns and may enable the detection of ancient ther-
mal highs and structurally deformed zones from
sample points 10 to 50 km away.

New method for determining environmental history by using
corals, Dade and Monroe Counties, Florida

Massive coral heads, Montastrea annularis, were
cored by J. H. Hudson and R. B. Halley with a newly
developed hydraulic coring device at Hens and
Chickens Reef ofl" Snake Creek in the Florida Keys.
Hens and Chickens Reef was selected because it
was observed by E. A. Shinn to have suffered severe
mortality in the latter part of 1969. Although this
time period had an unusually severe cold weather,
blame for coral deaths was attributed to manmade

26

factors by some, such as ( 1) silt from dredge opera-
tions, (2) aerial mosquito spraying on the nearby
Florida Keys, (3) septic-tank leakage through por-
ous limestone into marine environments, and (4)
oil pollution. Tree-ringlike annual density bands re-
vealed in X-r-adiographs of coral cores showed that
the coral growth rate at Hens and Chicken-s has re-
mained constant over the past 40 yr; this constant
rate shows no signs of man’s activities. Corals that
survived the 1969 event continued to grow at the
same annual growth rate (approximately 1 cm) as
they did in the early 1940’s, when human population
and development were far less significant than they
have been in the pas-t 10 yr. The event that killed
80 percent of the corals at Hens and Chickens in
1969 is clearly recorded in X-radiographs of the
surviving corals as a “stress band” of unusual den-
sity. Other stress bands that correlate with unsea-
sonably low temperatures occurred in 1964, 1958,
and 1942. The 1942 stress band is of even greater
density than the one associated with the 1969 kill.
Use of the permanent tree-ringlike method, in com-
bination with oxygen-isotope temperature analysis,
will allow environmental reconstruction of the past
500 yr or more and thus provide researchers a base-
line upon which to evaluate man’s recent impact on
the tropical and subtropical environment. The
method also allows comparison of modern coral
growth rates with those of corals of Pleistocene
age, which built up what are now the Florida Keys
some 125,000 yr ago.

Physical properties data banks to become a reality

As a part of the USGS Energy Resources Pro-
gram, C. K. Fisher reported a proposal to establish
a national system of. core libraries, operated per-
manently by either State Surveys or an equivalent
agency and supported by Federal, State, university,
and industry funds. The USGS will provide a large
part of the initial investment needed to organize and
develop these facilities. Preliminary planning has
indicated that 8 to 10 core libraries will be needed
to properly accommodate the material in all regions
of exploration activity, both onshore and offshore.

New facilities will be established to complement ex-.

isting State repositories, and support money for
expansion and operation of the established facilities
will be made available, hopefully, beginning in fiscal
year 1977. A core repository for the Rocky Moun-
tain area is now being developed near Denver for
any material not required or requested by a State
agency. Also, steps are being taken to provide finan-
cial support for the operating fund of an industry-

 

GEOLOGICAL SURVEY RESEARCH 1975

State-Federal cooperative core facility at California
State College in Bakersfield.

Secondary recovery of oil via microbial stimulation

To determine microbiological-biochemical tech-
niques that may accelerate or optimize water-injec-
tion methods now being used in the field for sec-
ondary recovery of oil, some preliminary laboratory
studies were made by F. E. Senftle and.F. D. Sisler.
These studies show that microorganisms that pro-
duce surface-tension-reducing chemicals during oxi-
dation of petroleum hydrocarbons (a desirable end
product of metabolism that increases migration of
oil through dense formations) reach a temporary
end point when these surfactant chemicals cause
autolysis of cells. This effect can be controlled by
continuous introduction of .additional water and
nutrients.

OIL-SHALE RESOURCES

Fossil-bearing pebbles in the Uinta Formation, Piceance Creek
basin, Colorado

In the east-central part of the Piceance Creek
basin, Colo., a lenticular bed of conglomerate, which
included a few fossil-bearing pebbles, was found by
R. B. O’Sullivan near the top of the Uinta Formation
of Eocene age. The angular dark-gray cherty lime-
stone pebbles were as much as 20 mm across and
contained fusulinids and impressions of brachiopods
and crinoid stems. The fusulinids were poorly pre-
served but appeared to be of Late Pennsylvanian or
Early Permian age. The pebbles suggest that Pale-
ozoic rocks were exposed, possibly to the east of the
Piceance Creek basin, during deposition of the Uinta
Formation.

Marlstone stratigraphic marker beds in the Uinta Formation,
Colorado

Mapping by W. J. Hail, Jr., in the south-central
part of the Piceance Creek basin, Colo., showed that
certain marlstone beds continue to provide useful
stratigraphic markers for subdividing the domi-
nantly elastic Uinta Formation of Eocene Age. Two
previously ‘unmapped marlstone units found in the
upper part of the Uinta Formation in the upper
Stewart Gulch area south of Piceance Creek were
mapped and are thought to be tongues of’ the Para-
chute Creek Member of the Green River Formation.
Although both the marlstone units in the Uinta For-
mation and the tongues of the Parachute Creek
Member of the Green River Formation found in the
Uinta Formation locally contain oil-shale beds, the
beds are too thin or too low in grade to be of eco-
nomic value.

MINERAL—RESOURCE AND MINERAL-FUELS INVESTIGATIONS 27

Contribution of analcime to silicon concentration in caustic

leachates from pyrolyzed oil shale

Investigations by G. A. Desborough of hot-water
leaching on analcime-bearing and analcime-free non-
dawsonitic spent-shale residue obtained from Fis-
cher assays showed that pyrolyzed analcime-bearing
oil shale contributes more water-soluble sodium,
aluminum, and silicon than analcime-free oil shale.
The total amount of dissolved solids leached from
the spent shale is largely a function of the mineral-
ogy of the oil shale. Examination of the leachate
obtained after hot caustic leaching of the analcime-
bearing and analcime—free oil-shale residue from
Fischer assays showed that analcime contributed
significant amounts of silicon to the leachate. This
silicon may inhibit hot caustic extraction of alumi-
num, on a commercial scale, from dawsonite-bearing
shale if analcime is present (Desborough, Mountjoy,
and Frost, 1975).

Excess aluminum in oil shale, Parachute Creek Member,

Green River Formation, Colorado.

Sample current-image electron-microprobe and
X-ray studies performed by G. A. Desborough on
analcime and dawsonite-bearing oil shale from the
Parachute Creek Member of the Green River For-
mation in the Piceance Creek basin, Colo., revealed
an aluminum compound that occurred in grains 10
to 20 ,um in diameter and contained no sodium, potas-
sium, or silicon. The X-ray diffraction studies re-
vealed no X-ray peaks that could be attributed to
this compound, and thus the compound may be
amorphous. This observation confirmed the presence
of an apparently amorphous aluminum compound
and verified calculations that indicated the presence
of excess aluminum in bulk chemical analysis of
some oil-shale samples.

Oil-shale resource, Piceance Creek basin, Colorado

An evaluation of the shale-oil resources in the
rich oil shales of the Parachute Creek Member of
the Green River Formation in the Piceance Creek
basin, Colo., by C. W. Keighin indicated that, in beds
3.05 m or greater in thickness and yielding 7.25 kg
or more of oil per tonne, there are 68 billion tonnes
of oil in place. Of this amount, 47 billion tonnes are
in beds that yield 8.7 kg or more per tonne. Re-
sources calculated for beds yielding 10.15 kg/tonne
and 11.6 kg/tonne are 25 billion tonnes and 11 bil-
lion tonnes, respectively.

It appeared that approximately 30 percent of the
shale oil contained in beds 3.05 m or greater in
thickness and yielding 7.25 kg or more of oil per

 

tonne in the Piceance Creek basin was contained in
the Mahogany zone.

NUCLEAR-FUELS RESOURCES

Uranium leaching in granitic rock

Rosholt and others (1973) suggested that the
granite of the Granite Mountains, Wyo., had been
depleted in uranium to depths as great as 50 m and
that this uranium might have formed the ore de-
posits that surround the Granite Mountains. Pre-
liminary results, obtained by J. S. Stuckless and
I. T. Nkomo from shallow (3 m) drill holes and one
deep (405 m) drill hole, support this hypothesis
and suggest that the depth of uranium leaching is
in excess of 400 m. The leached samples are gen-
erally fresh in appearance but are 50 to 80 percent
depleted in uranium relative to the radiogenic
daughter-product lead.

Core samples of the granite are highly variable
in chemical and petrologic characteristics. The rock
in the upper portion of the drill hole (approxi-
mately the upper 215 m) is typically hypidiomor-
phic-granular granite to quartz monzonite contain-
ing averages of 12 ppm U, 52 ppm Th, 54 ppm Pb,
and 4.4 percent K. Within this portion, the uranium
content ranges from 5 to 23 ppm. Samples from the
lower portion of the drill hole (215 to 405 m) are
xenomorphic-granular quartz-rich rocks that con-
tain lesser amounts of uranium (7.0 ppm) and
thorium (6.8 ppm) and more variable amounts of
potassium (0.5 to 6.3 percent). Fracture zones, 0.5
to 3.0 m thick, in both portions of the core exhibit
secondary enrichment of uranium (50 to 500 ppm).

Geologic controls of uranium depositional processes

Studies of the F. Brysch uranium mine, FallsCity,
Tex., by K. A. Dickinson and M. W. Sullivan sug-
gested that the deposit was originally an unoxi-
dized ore roll that was later oxidized. The host rock,
the lower unit of the Deweesville Sandstone Member
of the Whitsett Formation of the upper Eocene
Jackson Group, is well-sorted medium-grained felds-
pathic sandstone deposited in a beach environment
at or near a delta. A fluvial channel connected to
this delta may have formed the passageway for
uranium-bearing ground water and later for oxidiz-
ing water. The host sandstone contains much sili-
cified wood that, before alteration, may have pro-
vided a reducing environment for the precipitation
of the uranium. The ore minerals are meta-autunite
and metatyuyamunite. The upper unit of the De—
weesville in this mine comprises a lower part con-

28 GEOLOGICAL SURVEY RESEARCH 1975

taining corroded volcanic shards that appear to have
partially altered directly to montmorillonite and an
upper part lacking both montmorillonite and shards
but containing small lathy clinoptilolite crystals in
the interstices of the sandstone.

Studies by M. W. Green and C. T. Pierson revealed
the geologic factors that controlled deposition of
small uranium deposits in basal Dakota Sandstone
of Early( ?) and Late Cretaceous age in the Gallup
area of New Mexico. The uranium was either dis-
solved from preexisting deposits in the Morrison
Formation or leached from arkosic Morrison sedi-
ments. Uranium-bearing ground water from the
Morrison entered the Dakota in areas where either
the upper part of the Brushy Basin Member was
permeable because of sandy facies or the Brushy
Basin had been removed by erosion. A relatively
large accumulation of carbonaceous material in the
basal Dakota provided the reducing environment
that precipitated the uranium.

Fluvial drainage patterns of Eocene age and their implications
for uranium exploration

Paleocurrent maps of the Eocene Wind River For-
mation in the Wind River Basin, Wyo., by D. A.
Seeland defined promising uranium-exploration
target areas in which favorable lithologic conditions
are likely to occur and in which the rocks were de-
rived from the granitic core of the Granite Moun-
tains. These targets ranked in decreasing order are
( 1) the lower few kilometres of the Eocene streams
that drained northeastward from the Granite Moun—
tains just south of their confluence with the Eocene
Wind River, (2) the 40-km segment of the Eocene
Wind River extending westward from near Powder
River, and (3) the southeastern part of the Wind
River Basin, where the Eocene Wind River Forma-
tion has 21 Granite Mountain source, but upstream
from the area ranked first.

Crossbedding orientation measurements in the
Eocene fluvial sandstones of the Wind River Basin
were used to construct vector mean and moving
average paleocurrent maps, which define the stream
systems and source areas of the Eocene rocks of the
basin. The Eocene “Wind River” flowed east-south-
east across the northern part of the basin, left the
basin near the present town of Powder River, and
flowed eastward across the Casper arch into the
Powder River Basin. Northeasterly trending
streams carried coarse-grained arkosic sandstones
in which the Shirley Basin and Gas Hills uranium
deposits are found.

 

Formation rate at roll-type uranium deposits

Roll-type uranium deposits are commonly associ-
ated with large altered sandstone tongues that oc-
cupy areal extents of several tens of square kilom-
etres. Calculations by H. C. Granger and C. G. .War-
ren suggested that the alteration of most of these
tongues probably took less than 1 my. and commonly
must have occurred before the rocks were deeply
buried or indurated.

The calculations are based on estimates that relate
the flow rate (Darcy’s law) to dissolved oxygen
content (Henry’s law) to ground water, diagenetic
pyrite content of the host rock, and probable chemi-
cal reactions between the pyrite and the oxygen. In
a typical example, ground water probably percolated
through the rocks about 4,000 times as fast as the
altered zone advanced. If 50 ppb U were extracted
from the altering solutions, a moderately large
uranium deposit could be formed in about 50,000 yr.

Uranium potential of Lower Cretaceous rocks. Colorado

Plateau

Lower Cretaceous rocks in Colorado and Utah
may have potential for uranium deposits because of
their similarity to the major uranium-bearing for-
mations of the Colorado Plateau. Studies by L. C.
Craig indicated that the Lower Cretaceous Burro
Canyon Formation consists of a sequence of alter-
nating sandstone and mudstone that was derived in
part from source areas south of the Four Corners
area. The sediment was deposited in a fluvial system
that trended northward in southwestern Colorado
and adjacent Utah and eastward to northeastward
in west-central Colorado. The subsurface extensions
of two sandstone lobes in west-central Colorado
along the southwestern margin of the Piceance
Creek basin may have provided the proper geologic
habitat for uranium deposition.

Uranium potential of Upper Cretaceous rocks, Crook County,

Wyoming '

The Fox Hills and overlying Lance Formations,
which accumulated on a coastal plain during the final
regression of the Cretaceous interior sea, are ob—
jects of increasing uranium-exploration activity.
Studies by H. W. Dodge, Jr., and J. D. Powell indi-
cated that the Fox Hills was deposited in marine
delta-front and strand-plain environments and that
the Lance was deposited in fluvial upper-deltaic-
plain environments. The Fox Hills consists of 25 m
of lenticular to tabular claystone, siltstone, and
sandstone. The Lance contains a distributary chan-
nel facies and an interdistributary facies. The chan-

MINERAL-RESOURCE AND MINERAL-FUELS INVESTIGATIONS

nel facies consists of fine-grained to very fine
grained, partly calcareous sandstone; lag deposits
containing dinosaur bones, claystone clasts, and
wood fragments; and slump breccias in the larger
channels. Largescale trough crossbedding is com-
mon in the channels, and ripple structure is com-
mon in the upper parts of smaller channels. The
channels are nearly straight, and the bases are con-
vex downward in cross section. Transport directions
in the channels are generally southeast. Organic-
rich mudstone, clayey siltstone, and sandstone were
deposited in the interdistributary areas of the
Lance.

Epigenetic uranium deposits of intermediate
grade have been found in the Fox Hills and Lance
Formations. Reconnaissance radiometric surveys re-
vealed several low-intensity anomalies ranging from

3 to 10 m in diameter in the lower part of the '

Lance. The uranium deposits may be related to local
structural features and to natural gas deposits.

Uranium-bearing pegmatites in the Kettle River Range

Uranium-bearing pegmatites in the Kettle River
Range,‘ northern Ferry County, Wash., are concen-
trated in the wall rocks of gneissic granodiorite
that is equivalent to the Cascade Granodiorite of
Daly (1912). Geologic mapping by R. C. Pearson in
the Togo Mountain quadrangle showed that most
,pegmatites lie within 2 km of the several grano-
diorite plutons. Only those near the largest pluton,
mainly in the vicinity of Mount Leona, show evi-
dence of having been prospected. No uranium min-
erals were observed during the mapping of the
pegmatites near the granodiorite bodies in the north-
eastern part of the quadrangle (Independence Creek
and north of Little Boulder Creek), but they may
warrant further investigation.

The Midnite uranium mine, Stevens County, Washington

The Midnite mine in Stevens County, Wash., is
one of only two mines in the United States cur-
rently producing uranium from discordant deposits
in crystalline host rocks. According to J. T. Nash
(USGS) and N. Lehrrnan (Dawn Mining Co.), the
orebodies are in metamorphosed, steeply dipping
Precambrian pelitic and calcareous rocks of a roof
pendant adjacent to a Cretaceous porphyritic quartz
monzonite pluton. Annual production is about 120,-
000 t of ore containing an average of 0.23 percent
U308. Irregular orebodies as much as 75 m wide, 200
m long, and 50 m thick are found within 100 m of
the pluton. Near-surface ore is oxidized, but ore at
depth contains pitchblende, coffinite, and abundant,

 

29

pyrite and marcasite. The ore is in disseminations
along foliation in replacements and stockwork frac-
ture fillings. The richest ore is found in high-angle
fault and shear zones and in stockworks of hornfels
near irregular intrusive contacts. Ore deposition ap-
parently was not stratigraphically controlled. The
host rocks are graphitic phyllite and schist. Amphib-
olite sills and dacite dikes locally contain ore. Al-
teration of diopsidic bands to green montmorillonite
is the only common ore-associated alteration noted.
Background uranium values in the pluton are about
12 ppm, but these rocks are not strongly altered,
and no veins or significant ore has been found there.
A simple genetic link between the pluton and the
orebodies is not apparent. Several processes of uran-
ium emplacement, including some supergene enrich-
ment, probably occurred in this mine.

Uranium- and coal-bearing Tertiary rocks

One of the most important coal-bearing areas in
the Powder River Basin, if not in all of the United
States, is the area surrounding and extending about
80 km south of Gillette, Wyo. Important uranium
deposits are present in the southern and southwest-
ern parts of the basin. Uranium and coal are present
in the upper part of the Paleocene Fort Union
Formation and the lower part of the Eocene Wa-
satch Formation. Low-grade uranium deposits are
reported from carbonaceous beds in the lower part
of the Upper Cretaceous Lance Formation north and
east of Gillette. These conclusions are the result of
continued regional mapping and study of subsurface
data throughout large areas in the Powder River
Basin of eastern Wyoming and adjoining parts of
southeastern Montana by N. M. Denson and G. H.
Horn (1975).

Uranium vein localized near old erosion surface

In the Cochetopa district, Saguache and Gunni-
son Counties, Colo., studies by J. C. Olson indicated
that the principal uranium deposit in the district, at
the Los Ochos mine, is localized near the old erosion
surface on which Oligocene volcanic rocks were de-
posited. Contours drawn on this ancient surface
show the position of the valley of the ancestral
Cochetopa Creek, which flowed northward through
the district, slightly east of its present position. The
uranium vein is located along the Los Ochos fault
near the point where it is crossed by the prevolcanic
Cochetopa valley. This localization suggests the pos-
sibility that the intersection of the fault and the
prevolcanic valley may have provided the conditions
necessary to cause deposition of uranium from Ter-

30 GEOLOGICAL SURVEY RESEARCH 1975

tiary ground or from surface waters moving down
the ancient surface on pre-Tertiary rocks.

Four varieties of thorite in Colorado pegmatite

Four rare-earth-rich varieties of thorite, charac-
terized by different colors (brown, yellow, orange,
and black), are present in narrow fracture fillings
in the Seerie pegmatite near Pine, Colo., according
to M. H. Staatz. The orange and black varieties are
metamict; the brown and yellow varieties are not.
The black, orange, and yellow varieties are com-
monly found together; the black variety forms a
core surrounded first by orange and then by yellow.
The black variety has 15 percent U03, the yellow
and orange varieties have 7 percent U03, and the
brown has only about 3 percent U03. The brown
variety contains 5 percent Fe, about fifteen times
as much as the other varieties. Rare-earth content
of the four thorites ranges from 17 to 20 percent,
more than has been reported from any other thorite.
The rare earths in these minerals are also unusual
in that they are principally of the yttrium group.
Ytterbium is the commonest lanthanide in all four
thorites.

A nuclear-track technique for uranium analysis of water

A nuclear-track technique for rountine sub-part-
per-million uranium analysis of water was developed
for use at the USGS reactor facility by G. W. Reim-
er. A small quantity of water, typically less than 1
ml, is placed into a similarly sized container. This
procedure can be done in the field if desired. A
fission-track detector is placed in the container,
which is then sealed. The container is placed in a
nuclear reactor and irradiated; the detector is re-
moved and etched to develop the fission tracks that
have resulted from the irradiation. Finally, the
tracks recorded in the detector are counted by using
a microscope. The number of tracks is related di-
rectly to uranium concentration. The method is
rapid, requires only a small quantity of sample, and

reduces the risk of sample contamination.
Y

Thorium deposits, Wet Mountains, Colorado

Thorium deposits in the Mount Tyndall quadran-
gle and vicinity are found in carbonatite dikes,
syenite dikes, barite veins, smoky quartz-barite
veins, and iron-oxide-rich shear zones and fractures,
according to T. J. Armbrustmacher. The carbonatite
dikes, also commonly rich in rare-earth elements,
are more abundant in the northern part of the
quadrangle near the alkalic igneous complexes at
McClure Mountain, Gem Park, and Democrat Creek.

 

GEOTHERMAL RESOURCES

Raft River geothermal area, Idaho

Extensive geophysical, geological, and hydrologic
studies by the USGS during 1974 in the Raft River
area of southern Idaho led to the siting of a 1,526-m'
exploratory well drilled by the Idaho National En-
gineering Laboratory (ERDA) . Bottom-hole temper-
ature is 147°C, slightly greater than the 135° to
145°C predicted by Mitchell and Young (1973) from
SiO2 and Na—K-Ca analyses of water from shallow
wells. Artesian flow from the deep well exceeded
60 l-s—1 initially but has since decreased to about
20 1s“.

The Raft River valley lies at the northern margin

~of the Basin and Range province and is a north-

trending late Cenozoic downwarp bounded by normal
range-front faults on the western, southern, and
eastern sides. Faulting within the basin along fault
sets parallel to the basin margins continued into late
Pleistocene time. Geologic studies by P. L. Williams
and K. L. Pierce (unpub. data, 1975) showed that
the geothermal anomaly near Bridge in the south-
ern part of the valley is located along such a north-
trending fault set where it intersects an east-north-

«east structure, probably a right-lateral fault, that

passes through the Narrows of the Raft River and
separates widely different structural styles in the
southern Jim Sage Mountains west of the valley.
The Raft River anomaly appears to be an example
of fault-intersection control of hot-water movement.

Gravity, magnetic, refraction, seismic, resistivity,
audiomagnetotelluric, self-potential, and telluric cur-
rent surveys have been made in the Raft River area
by D. R. Mabey, A. A. R. Zohdy, H. D. Ackerman,

~ D. B. Hoover, D. B. Jackson, and J. E. O’Donnell.

The geophysical data suggest that the maximum
thickness of Cenozoic sedimentary and volcanic rock
underlying the valley is about 2 km and that the
valley is bounded by normal faults on the east and
south and by a complex system of faults on the west.
Large gravity, magnetic, and total-field resistivity
highs within the valley immediately east of the Jim
Sage Mountains reflect an igneous rock mass, at a
relatively shallow depth, too old to relate directly to
a geothermal system. The seismic interpretation di-
vides the valley into four separate areas in which
the Cenozoic rocks have distinctive seismic velocities.
These areas appear to relate to known or inferred
structures and to a suspected zone of shallow warm
water. Resistivity anomalies reflect compositional
variations in the Cenozoic rocks and variation in
degree of induration and alteration. The resistivity

MINERAL-RESOURCE AND MINERAL-FUELS INVESTIGATIONS

soundings show a 2 to 5-ohm-m resistivity unit with
a thickness of 1 km underlying a large area of the
valley, which may in part be indicative of hot water.
Observed self-potential anomalies are believed to
mark zones where warm water is ascending toward
the surface.

The geological and geophysical investigations at
the Raft River were supplemented by 4 core holes
83 to 433 m deep, drilled under the supervision of
E. G. Crosthwaite. Data collected from these holes
included cores, temperature logs, radioactive logs,
electrical logs, caliper logs, depths to water, pres-
sure heads, and information on fluid chemistry.

Late Cenozoic ring faulting and volcanism in the Coso
geothermal area of California

The Coso Mountains of southeastern California
are underlain principally by Mesozoic granitic rocks
that are partly veneered by late Cenozoic volcanic
rocks. In apparent decreasing age, the volcanic units
include (1) widespread basaltic flows, mostly in the
southeastern and central parts of the range, (2)
dacitic flows and tuff capping ridges along the west-
ern side of the range, and (3) rhyolitic domes and
flows and basaltic cones and flows in the south-cen-
tral part of the range. Recent mapping by W. A.
Dufiield (1975) showed that all of these volcanic
rocks are encompassed by an oval-shaped zone of
late Cenozoic ring faulting that measures about 40
km east-west and 45 km north-south and defines a
structural basin. Most of the Coso Mountains and a
slice of the adjacent Sierra Nevada lie within this
ring structure. The young rhyolites range in age
from 960,000 to 40,000 yr (Lanphere and others,
1975) and, with associated active fumaroles, occupy
a north—trending structural and topographic ridge
about 18X10 km near the center of the basin. The
ring structure and associated volcanic rocks suggest
a large underlying magma chamber that has period-
ically erupted lava to the surface during the past
few million years. Planned geophysical and seismic
studies will search for any remaining magma to help
assess the geothermal resources of the area.

Quaternary volcanism in the Clear Lake area, California
Geologic mapping of the Clear Lake volcanic field,
Calif., by B. C. Hearn, Jr., J. M. Donnelly, and F. E.
Gaff (unpub. data, 1975) has shown that faults are
numerous and predominantly northeast and north-
northwest. There is evidence for recent strike-slip
movement on one north-northwest zone. Potassium-
argon age, magnetic polarities, and C-14 dates from
the complex volcanic sequence range from 2.5 my
to about 15,000 yr. Much of the field is younger than

 

31

about 1.1 m.y., and the central part is younger than
0.55 m.y. The youngest silicic eruption is 0.9 m.y.
Geophysical evidence suggests that there is a par—
tially fluid magma chamber at depth beneath the
volcanic field. Repeated silicic volcanism, lack of
welded tuf‘fs, and lack of large-scale caldera collapse
suggest that the volcanic system is in an early evolu-
tionary stage. According to the model of Smith and
Shaw (1973), the size and youth of the Clear Lake
system infer that the volcanic field and its surround-
ings have considerable geothermal potential.

Youthful volcanism in the San Francisco volcanic field, Arizona

Geologic mapping by E. W. Wolfe, G. E. Ulrich,
R. B. Moore, and R. F. Holm, with K-Ar dating by
E. H. McKee (USGS) and P. E. Damon (Univ. of
Arizona), showed that very young silicic rocks are
present in the eastern part of the San Francisco
volcanic field. Among the youngest are obsidian in
Doyle Saddle on San Francisco Mountain (0.68:
0.01 m.y.) , the Mount Elden dacite dome (0.55-£0.03
and 0.56:3 m.y.), the Sugarloaf rhyolite dome
(0.21:0.02 my. and 0.13:0.1 m.y.), the O’Leary
Peak rhyodacite (0.23:0.04 and 0.14:0.07 m.y.),
and the Robinson rhyodacite dome (0.27 10.2 and
0.15:0.1 m.y.). Even younger ages (50,000:L-14,000
yr and 46,000t46,000 yr) have been determined for
basaltic andesites from vents with small rhyodacite
plugs. These occurrences suggest that an area in-
cluding San Francisco Mountain and extending east-
ward about 32 km from the mountain ought to be a
prime target area for geophysical detection of intru-
sive bodies, anomalous seismicity, and geothermal
energy. This area also contains most of the known
young basaltic volcanic rocks, including the 910-yr-
old Sunset Crater.

Gravity mapping by J. D. Hendricks showed an
arcuate activity low west of the San Francisco
Mountain area. The gravity low, in an area where
silicic volcanic rocks are concentrated, suggests the
possibility of a low-density silicic intrusion Within
the crust in this area.

Geothermal significance of rhyolite age progression in Oregon
Late Cenozoic rhyolitic domes, vent complexes,
and associated ash-flow tuffs in southeastern Oregon,
which are similar in many respects to silicic volcanic
complexes that are associated with most of the
world’s electric-power-producing geothermal fields,
were studied by N. S. MacLeod and E. H. McKee.
Most of the 150 domes occur in two diffuse 250-km-
long belts that trend N. 75° W. The northern belt, in
the High Lava Plains province, extends from New-

32 GEOLOGICAL SURVEY RESEARCH 1975

berry Volcano near the Cascade Range to beyond
Harney Basin; the southern belt, in the northern
part of the Basin and Range province, extends from
Yamsey Mountain, 80 km south of Newberry, to or
beyond Beatys Butte near Catlow Valley. A few
domes occur between the two belts, particularly in
the western part of the area. The domes show a re-
markably regular increase in age towards the east,
on the basis of 38 K-Ar dates, and thus an earlier
suggestion by G. W. Walker is confirmed. The young-
est rhyolites are associated with Newberry Volcano
on- the western end of the northern belt, where many
obsidian flows and ash falls and flows are less than
7,000 yr old. The dome at McKay Butte, on New-
berry’s western flank, is 0.6 m.y.; China Hat, on the
eastern flank, is 0.8 m.y. Progressing eastward, the
dome at East Butte is 0.9 m.y.; Quartz Mountain is
1 m.y.; Long Butte is 2.3 m.y.; Squaw Ridge is 3.6
m.y.; Fredericks Butte is 3.9 m.y.; Cougar Mountain
is 4.3 m.y.; and Glass Butte is 4.9 m.y. Twelve dated
domes farther east are progressively older to Duck
Butte, which is 10 m.y. The youngest dated dome in
the southern belt, at its western end near Yamsey
Mountain, is 4.7 m.y. Progressing to the east and
southeast, the dome at Partin Butte is 5.0 m.y.;
Black Hills is 5.4 m.y.; and Hager Mountain is 5.9
m.y. Seven dated domes farther east progress in age
to 10.4 m.y. at Beatys Butte. Dated domes between
the two belts include one near Stams Mountain,
which is 4.5 m.y., one near Bald Mountain, which is
5.1 m.y., and three near Horse Mountain, which
range from 6.7 to 6.9 m.y. The regularity of the age
increase towards the east permits the construction
of isochrons that can be used to predict the age of
most undated domes to within about 0.5 m.y. Avail-
able K-Ar dates on extensive ash-flow tuff sheets
indicate that their probable vent areas also fit this
age progression. Graphs of areal extent of domes
versus age and of number of domes versus age both
suggest a major period of rhyolitic volcanism about
7 m.y. ago, followed by a progressive decline that
extends to the late Quaternary. The only domes that
are less than 2 m.y. occur in the immediate vicinity
of N ewberry Volcano. Geothermal areas east of the
Cascade Range that have cooling silicic intrusive
bodies as their heat source thus are probable only
near Newberry.

Geothermal reconnaissance of young volcanic areas around

the Colorado Plateau

Age and composition data on upper Cenozoic vol-
canic rocks were collected by P. W. Lipman along
the margins of the Colorado Plateau, in the volcano-

 

tectonic setting where a significant geothermal re-
source is currently being developed in the Jemez
volcanic field of northern New Mexico. Upper Ceno-
zoic silicic rocks that might indicate' the presence of
sizable shallow magma chambers seem to occur
mainly in the White Mountains of Arizona and in
the Mount Taylor and Taos Plateau volcanic fields
of New Mexico, although some do occur in the J emez
Mountains and the San Francisco Mountain area of
Arizona as well; these latter areas are currently
being studied in detail by other USGS geothermal
projects. Stratigraphic and age relations of young
rocks are poorly known in the two New Mexico vol-
canic fields, and so brief field reconnaissance studies
have been supplemented by K-Ar dating by H. H.
Mehnert.

In the Mount Taylor area, volcanism began about
3 m.y. ago with the widespread eruption of pre-
viously unrecognized lava flows and domes of vis-
cous trachyte that extend from the site of the over-
lying Mount Taylor cone northeastward for at least
30 km. The Mount Taylor stratovolcano was con-
structed of rocks ranging from alkali andesite to
rhyolite between about 3 and 2 m.y. ago, concurrent
with the eruption of silicic alkalic basalt around its
flanks. The youngest basalt capping adjacent high
mesas is about 1.5 m.y. old.

The Taos Plateau volcanic field consists of a clus-
ter of at least 25 stratovolcanoes and shields, rang-
ing in composition from olivine andesite to silicic
rhyolite, that are concentrated mostly within an
area about 40 km in diameter within the Rio Grande
graben in northern New Mexico. These volcanoes
are all morphologically young, and one rhyolite lava
dome is about 4 m.y. old. The Taos Plateau volcanoes
were partly buried by flows of tholeiitic and alkalic
basalt as young as about 2 m.y. This young vol-
canism is more voluminous and compositionally di-
verse than any other within the Rio Grande graben,
with the exception of the J emez volcanic field. The
clustered, compositionally diverse volcanoes of the
Taos Plateau field may have resembled the Jemez
field prior to the ash-flow eruption and collapse of
the Valles caldera, but any large, shallow body of
silicic magma underlying the Taos Plateau prob-
ably had largely crystallized by the time the basalts
erupted from within the volcanic cluster.

Fault-controlled hot-spring systems of central Colorado

Several hot springs lie in the Buena Vista and
Poncha Springs quadrangles in central Colorado,
mapped by G. R. Scott. Poncha, Mount Princeton,
Hortense, and Cottonwood Hot Springs lie along

MINERAL-RESOURCE AND MINERAL-FUELS INVESTIGATIONS 33

intensely brecciated fault zones bordering the Upper
Arkansas Valley graben segment of the Rio Grande
Trough. These fault zones have been recurrently ac-
tive at least since early Miocene time and apparently
project to great depth. Zeolitized rock locally ex-
tends thousands of metres out into the footwalls of
some of the faults and probably formed in the roots
of hydrothermal systems at an early stage of the
faulting. The modern hot springs apparently lack
an adequate recent source for magnetic heat and
thus derive their heat from deep circulation of
water along the faults ystems.

Exploration of geothermal systems by aerial thermal infrared

surveys

Although thermal infrared surveys provide a di-‘
rect measure of surface heating, the variations in
surface temperature due to geologic-topographic
factors tend to mask the effects of geothermal heat-
ing. A thermal model was used by Kenneth Watson
(1974) to demonstrate that measurements of the
mean diurnal temperature, together with reflectance
measurements and slope information, can be used
to map the geothermal flux. Theoretical calculations
show that the error estimate of the mean diurnal
temperature (Vac) falls off rapidly with increasing
sample measurements per diurnal cycle (650 HFU
at 1 sample/cycle and 75 HFU at 3 samples/cycle).

The thermal model was also‘used to examine the
optimum times in the diurnal cycle at which to ob-
tain an estimate of Vac. A thermal image and a re-
flectance image of the Raft River area in Idaho ac-
quired at the optimum time for 1 sample/ cycle show
the presence of warm thermal anomalies, which do
not coincide with changes in the reflectance image,
Probe measurements in the vicinity of this area con-
firm the presence of such an anomaly.

Reservoir engineering of vapor-dominated geothermal systems ~

Manuel Nath'enson calculated various properties
for the vapor-dominated reservoir system of Larder-
ello, Italy, by using available published data. Meas—
urements made to date on flowing steam wells have
almost always been taken at the wellhead. To better
understand the reservoir mechanics, these wellhead
quantities were converted to values at the well bot—
tom. In two sample wells, large variations in well?
head temperature with flow at a particular time are
shown' to correspond to nearly constant tempera-
tures at the well bottoms. For a third well, trends in
wellhead values correspond to similar trends at the
bottom of the well. Wellhead temperatures .in flow-

 

ing wells measured over a period of years have also
been converted to equivalent bottom temperatures.
These calculated temperatures can increase, de-
crease, or remain nearly constant, depending on the
local environment of the particular well.

The initial fluid mass in place in the northeastern
zone of Larderello has been estimated by using data
on shut-in pressures and total mass production. The
reservoir thickness needed to store this mass of fluid
has been calculated as a function of porosity and
initial volume fraction of water in average pores.
The thickness is 19 km if it is assumed that there
is 5 percent porosity with steam as the only fluid to
832 m and 20 percent porosity and 10 percent pore
volume to be liquid water.

Annotated bibliography of volumetric properties of geothermal
brine

A complete annotated bibliography of the volu-
metric properties of geothermal brines was compiled
from the 1928—1974 literature by R. W. Potter III,
D. R. Shaw, and J. L. Haas, Jr. (1975). This compi-
lation contains data useful in designing energy ex—
traction systems for geothermal brine fields. Lab-
oratory experiments to fill the many data gaps are
presently being undertaken by Potter.

Ground movement in geothermal areas of California and Idaho

B. E. Lofgren reported that survey networks of
vertical and horizontal control are now monitoring
possible ground movement in The Geysers and Im-
perial Valley, Calif., and the Raft River valley,
Idaho, geothermal areas. During the summer of
1975, similar nets were established in Long Valley,
Calif. Also, vertical extensometers and tiltmeters
are being installed at selected sites in Imperial Val-
ley to detect tectonic trends prior to geothermal de-
velopment.

Three significant occurrences measured by the
monitoring program prior to geothermal develop-
ment are:

1. A northward tilt in Imperial Valley of about 13
cm in the 85 km from Calexico on the north to
the county line north of Niland from spring
1972 to spring 1974.

2. An apparent 5 mm/yr of right-lateral ground
movement along a northwest-trending fault
zone in the Buttes area, Imperial Valley.

3. As much as 0.8 m of land subsidence in an area
of heavy ground-water pumping north of
Malta in the Raft River valley.

REGIONAL GEOLOGIC INVESTIGATIONS

NEW ENGLAND

Geologic quadrangle mapping at 1:24,000 by the
USGS in cooperation with the States of Connecticut
and Massachusetts progressed satisfactorily in 1974.
More than 56 percent of the bedrock and 49 percent
of the surficial geologic quadrangle mapping of
Massachusetts has been completed. In Connecticut,
97 percent of the bedrock and 82 percent of the sur-
ficial geologic quadrangle mapping has been com-
pleted. In addition, substantial progress was made
toward compilation of revised intermediate-scale
(1:125,000) bedrock geologic maps of both States.
These compilations have been facilitated by the use
of moderately new remote-sensing data from aero-
magnetic, airborne radiometric, and gravity sur-

veys, plus side-looking radar imagery. These data,.

combined with published and open-filed geologic
quadrangles, yield an overall regional structural
synthesis for this complex metamorphic terrane.
Geophysical data in offshore areas have indicated
major structural trends as well as the nature of
unconsolidated sediments. The USGS. is presently
engaged in cooperative programs with the States of
Massachusetts, Connecticut, and New Hampshire.
Results of last year’s research, summarized below,

show a concentration of effort in Massachusetts, the.

State with the greatest financial participation.

STRUCTURAL 'AND STRATIGRAPHIC STUDIES

Structural pattern in southern New England

A summary of geologic interpretations of geo-
physical, topographic, radar, and LANDSAT line-
aments in southern New England by P. J. Barosh
showed that the pervasive faulting known in the
Triassic rocks of the southern Connecticut River
valley is also present in the older basement rocks.
Lineaments indicative of fault extensions and prob-
able faults, along with mapped faults, show that
southern New England is cut by several important
northeast-trending fault zones. Northerly trending
faults lie between these zones in places and cut some

34

 

of the northeast-trending faults. Several important
easterly trending fault zones are also present, mainly
in southeastern New England. These three trends
appear to have formed contemporaneously because
they cut one another. All three are cut by prominent
northwest-trending faults with little displacement.
Several northeast-trending faults have apparent
right-lateral displacement.

Base of the Quinebaug Formationr'southeastern Connecticut

Layered metavolcanic rocks as much as 800 m
thick structurally below and in the Honey Hill-Lake
Char fault zone in the northern Old Mystic quad-
rangle and southeastern J ewett City quadrangle
(Ice. 1, index map) lie conformably on quartzite and
schist of the Plainfield Formation. Some of these
metavolcanic rocks are similar to those of the Quine—

I’q'TAx
/

NEW ENGLAND
STATES

I
\r‘ MAINE TI

      

EST—“J~
T

5
{3“6144. 6
4—3-—
:CONNECTICUT'

. IRI‘
15 13 .1
1

     

   

REGIONAL GEOLOGIC INVESTIGATIONS 35

baug Formation lying in and above the Honey Hill
fault zone. No clear stratigraphic boundary between
the two metavolcanic sequences can be readily dis-
cerned through the cataclasis. However, the meta-
volcanic rocks of the lower plate seem to be more
quartzose and contain layers of mafic—poor felsic
rock not found in the metavolcanic rocks of the up-
per plate except in the fault zone. On this basis,
metavolcanic rocks above the fault zone are being
mapped by H. R. Dixon and Richard Goldsmith as
Quinebaug Formation, whereas those below the fault
zone are being mapped as a separate metavolcanic
unit above the Plainfield Formation. It is pos ible
that the metavolcanic rocks on both sides of the fault
zone represent one continuous sequence in which the
mafic—poor felsic layers occur only in the lower part.

If so, little displacement need have occurred along
the Honey Hill-Lake Char fault system, as Lundgren
and Ebblin (1972) suggested. However, the situa-
tion is perhaps analogous to that along strike in
eastern Massachusetts, Where K. G. Bell (1973, p.
28) described two metavolcanic units in juxtaposi-
tion. He postulates an unconformity between meta-
volcanic rocks of the Blackstone Series in a terrane
extensively intruded by Dedham Granodiorite, and
metavolcanic rocks of the overlying Marlboro and
Nashoba. Formations in a terrane in which there is
no Dedham Granodiorite.

Three periods of cataclastic deformation in southeastern
Connecticut

Three periods of cataclastic deformation were
demonstrated by H. R. Dixon and Richard Gold-
smith in the area of the Preston Gabbro in the Jew-
ett City and Old Mystic quadrangles (loc. 1). The
earliest deformation involved regional metamor-
phism and subsequent early cataclasis of the Quine-
baug Formation and overlying metasedimentary
rocks, followed by intrusion of the gabbro, as shown
by intrusive relationships. The southern end of the
gabbro near Ayer Hill and Prentice Mountain is a
composite mass consisting of a core of hornblende
gabbro surrounded by hornblende diorite and with
discontinuous masses of quartz diorite, locally
trondhjemite. These rocks appear to be comagmatic.
The quartz diorite phase, in places showing little or
no foliation or cataclasis, cuts and encloses fine-
grained mylonitic rocks of the Quineb-aug Forma-
tion. On the northwestern and southwestern sides
the gabbro or its trondhjemite differentiate, with a
primary igneous fabric, crosscuts layering and folia-
tion of the Quinebaug and contains inclusions of
gneissic or mylonitic Quinebaug.

 

A second stage of cataclastic deformation affected
the entire gabbro body and surrounding rocks. The
most intense deformation was along the eastern and
southern sides of the gabbro, where the gabbro and
underlying rocks of the Plainfield Formation and
alaskite gneisses of the Sterling Plutonic Group are
converted to mylonite in a belt a few tens of metres
thick. These mylonites are along the southern limit
of the Lake Char fault and the eastern limit of the
Honey Hill fault, where the two faults join. All rocks
are cut by a north-south-trending system of normal
faults accompanied by brecciation, hydrothermal al-
teration, and silicification. These faults belong to the
third stage of deformation and are part of the Lan-
tern Hill fault system of probable Triassic age.

Radiometric chronology and maior structures of the Berkshire
massif, western Massachusetts

Three groups of rocks, interlayered with the
Hoosac Formation (Lower? Cambrian or older)
along the east margin of the Berkshire massif (loc.
2), have been dated by Rb—Sr whole-rock techniques.
Cataclased foliated granite yielded an age of 894-:
58 my. A suite of metavolcanic or metaigneous rocks
yielded an ageiof 1.11 :31 by. Weakly foliated gran-
ites, interpreted to be in fault contact with the
Hoosac, yielded an age of 605:50 my. (D. G. Brook-
ins and S.A. Norton, 1975). These results suggested
to Norton the following (partial) history of the rocks
at the east margin of the Berkshire massif:

Volcanic rocks deposited, 1.1 b.y.

Grenville orogeny plus intrusion of granite gneiss, 0.9
b. .

Intrision of granites, 0.61 b.y.

Deposition of Hoosac Formation and younger rocks, 0.6 to
0.44 by

Tectonic intercalation of Precambrian rocks with Paleo-
zoic metasedimentary rocks, probably during Taconic
time.

A 30-km-long east-west cross section of the Berk-
shire massif along lat 42°15’ N. (loo. 3), extending
from miogeosynclinal rocks of the Stockbridge Val-
ley on the west to the overthrust eugeosynclinal
Hoosac and younger sequence on the east, is com-,
plete. On the basis of the results of this study, N. M.
Ratclifl‘e suggested that the Precambrian massif at
its widest part is composed of nested low-angle over-
thrusts that extend eastward in complexly deformed
synclinal and anticlinal structures. The youngest
and structurally highest thrust slices are confined to
the central portion of the massif. The geometry of
these slices indicates that‘the major structure of the
massif is broadly synclinal rather than anticlinal,
and thus the term Berkshire anticlinorium is mis-

I

36

leading. Structural analysis of minor drag folds
from zones of blastomylonite indicates slip line azi-
muths from 70° to 160°. The Beartown Mountain
slice overrides the Paleozoic miogeosynclinal se-
quence for a minimum distance of 21 km, and a
higher slice, the October Mountain slice, in turn
overrides the Beartown Mountain slice for a mini-
mum distance of 15 km in the slip direction. A mini-
mum of 36 km of tectonic foreshortening is sug-
gested for the rocks of the Berkshire massif. Later
folding of the thrusts may account for an additional
10_ km of shortening. The cross section indicates
that the outcrop width of massif rocks may have
been in excess of 45 km prior to Taconic orogenesis.
The rocks may have been situated at least 21 km
farther east than their present location with respect
to the underlying miogeosynclinal sequence. A re-
stored position places the rocks above the crest of
the regional positive Bouguer anomaly.

Major structures east of the Monson Gneiss, central

Massachusetts

A northeast- and north-trending 1.6-km-wide syn-
cline or synclinorium, composed chiefly of layered
rocks of the Mount Pisgah Formation, was mapped
by J. D. Peper east of and adjacent to the Monson
Gneiss in the Palmer quadrangle (loc. 4). Evidence
for overturning is based on a few relict sedimentary
structures that indicate tops of beds to the east. The
Bone Mill Brook fault, a major regional fault asso-
ciated with cataclastic rocks along the eastern edge
of the Monson Gneiss in the Stafford Springs, Mon-
son, and Palmer quadrangles, truncates the axis of
the syncline near the border of the Monson and
Palmer quadrangles. A discordant northward-widen-
ing body of foliated porphyritic quartz monzonite
invades the east limb of the syncline and invades
and obliterates a north-trending anticline in the east-
ern and northeastern parts of the Palmer quad-
rangle.

Lithostratigraphic sequence in East Brookfield quadrangle,
Massachusetts

Recent mapping by J. S. Pomeroy demonstrated
that the subdivision of a thick sequence of high-
grade metamorphic rocks in northeastern Connec-
ticut (Peper, Pease, and Seiders, 1975) can be ex-
tended northward into the East Brookfield quad-
rangle (loc. 5). A sequence of mostly gray to less
common, slightly rusty weathering felsic gneiss is
the dominant- rock type in the eastern part of the
quadrangle. Thin units of sulfidic schist occur locally
throughout this part of the section. Terrigenous
sands and silts with minor euxenic muds and silts

 

GEOLOGICAL SURVEY RESEARCH 1975

were the probable original sediments. Overlying
these rocks to the west are mappable units of
roughly equal proportions of rusty-weathering
gneiss/sulfidic schist and gray-weathering felsic
gneiss. The latter sequence represents an assortment
of euxenic muds and silts with influxes of terrigen-
ous and possible volcaniclastic debris. Rare occur-
ences of relict graded bedding in gray garnetiferous
gneiss indicate that the section is right side up.

Folded graded beds in the Worcester North quadrangle

A gray phyllite to mica schist unit with prominent
arenaceous graded beds crops out in the central part
of the Worcester North quadrangle (loc. 6). This
unit contains graded beds similar to those reported
by Peck (1972) in the Clinton quadrangle and in-
terpreted by him as a metaturbidite. According to
J. C. Hepburn, bedding reversals observed in large
exposures along Interstate 290» indicate a series of
isoclinal folds plunging moderately to the north-
northwest with amplitudes on the order of 100 m.

Deformation in rocks of the Concord-Framingham-Natick area,
eastern Massachusetts

Rocks in the Concord-Framingham-Natick area
(loo. 7) were deformed during three periods of de-
formation, according to A. E. Nelson. During the
first period, metamorphic schistosity (SI) formed
in the upper Cambrian to lower Paleozoic( ?) rocks
in response to ductile deformation that occurred in
the early stage of regional metamorphism. Near the
close of metamorphism, minor folds developed as
initial structures of the second deformation. As the
second deformation period continued, regional north-
to northeast-trending folds formed, schistosity (8,)
was folded, and a slip cleavage (Sz) developed 10-
cally. Cataclastic foliation (SK) associated with
deep-seated faulting was formed in the rocks during
a long interval. The third (Alleghenian) deforma-
tion period folded and faulted the Carboniferous
rocks of the Boston Basin. At this time a cleavage
(8,) also formed in some Carboniferous rocks, but
this cleavage has not been observed in the older
rocks west of the Boston Basin.

Basement structure beneath Cape Cod Bay, Massachusetts

A basement structure contour map of Cape Cod
Bay (loo. 8) compiled by R. N. Oldale and C. J.
O’Hara showed a prominent lineament trending
northeast from a point just north of Cape Cod Canal
to a point just south of Provincetown. This line-
ament, made up of a number of basement lows, may
represent a fault boundary separating strata of
Triassic or Jurassic age to the south from igneous

REGIONAL GEOLOGIC INVESTIGATIONS 37

and metamorphic rocks of pre-Triassic age to the
north.

Inferred post-Tertiary history of Cape Cod Bay

Interpretation of seismic profiles by R. N. Oldale
and C. J. O’Hara suggested the following geologic
history for Cape Cod Bay. During Tertiary time the
area underwent deposition and erosion similar to
those of the unglaciated Atlantic Coastal Plain. To-
ward the end of Tertiary time, erosion removed much
of the coastal plain strata, exposing basement rocks
and producing an extensive drainage system. This
surface is deeply buried by glacial drift deposited
in large part during the advance and retreat of the
last ice sheet. Fluvial erosion of the drift followed
ice retreat as sea ‘level rose toward its present level.
As the Holocene transgression proceeded, drowned
valleys became sites of estuarine deposition. Barrier
beaches and lagoons developed locally. These
beaches, now submerged to depths of 30 m or more,
constitute a significant source of deposits of sand
and gravel. Most recently, beach and bar deposits
are forming in shallow water, and silt and clay are
being deposited in deep water.

Volcanic sediments in the Boston Basin

Study of the rocks of the Boston Basin (loo. 9) by
C. A. Kaye showed that much of the sediment is vol-
canically derived from fine- and coarse-grained pyro-
clastics, most of which were somewhat reworked
and water deposited. The ashy tufi's have been tra-
ditionally classified as argillites, and the reworked,
coarser material as conglomerate and tillite. At least
three important intervals of eruption are recognized;
the first two were dominantly andesitic, and the
third was rhyolitic but with some mafic lavas. Two
cones have been identified: a very large stratovol-
cano that centers on Mattapan and a small andesitic
cone with evidence of hydrothermal (fumerolic) a1-
teration. Both cones were involved in the deforma-
tion of the basin and are lying on their sides.

Intrusion of Lucerne pluton, Hancock County, Maine

The Lucerne pluton (loc. 10) moved laterally dur-
ing intrusion, according to studies by D. R. Wones.
Mylonite zones subparallel to the western edge and
drag folds found in the metamorphosed Ellsworth
Schist on the eastern edge of the pluton both imply
motion from the south toward the northeast. Grav-
ity studies by J. ‘H. Sweeney (SUNY, Buffalo) indi-
cated that the Lucerne pluton is thicker toward the
south. A model of a rising magma flowing laterally
to the northeast explains the shape of the pluton,

 

its observed internal deformation, and the deforma-
tion of the intruded metasediments.

QUATERNARY GEOLOGY
Recessional moraines in southeastern Connecticut

Review by Richard Goldsmith (USGS) of map-
ping done in 1962 by J. W. Gaffney (then a student
at the Univ. of Massachusetts) in the Old Mystic
quadrangle (loc. 11), New London County, Conn.,
clearly confirmed the continuity of a set of minor
recessional moraines that extend from Long Island
Sound west of New London through the Stonington
area into Rhode Island. The two moraines lie 13 km
and 20 km, respectively, north of and parallel to the
terminal Charlestown-Harbor Hill moraine. The
northern moraine (Ledyard moraine) can be traced
northwestward as a positive feature across the Old
Mystic quadrangle from the western edge to the
northeastern corner. The southern moraine, called
the Rocky Hollow moraine by Gafi'ney, extends as a
line of patches of ablation till, till ridges, and ice-
contact deposits of sand and gravel from near 01d
Mystic to about 1 km south of North Stonington
Village. The Rocky Hollow moraine is alined with
two closely spaced moraines in the Niantic area to
the southwest and with morainic features mapped
by J. P. Schafer in the central Ashaway quadrangle
to the east. Schafer, in reconnaissance, has traced
this moraine for about 77 km from the Niantic area
into south-central Rhode Island (Schafer and Harts-
horn, 1965). The Ledyard moraine has not been
recognized in Rhode Island.

The moraines consist of loose bouldery till in
places, with minor sand and gravel, usually showing
hummocky topography; accumulations in’ a few
places of boulders piled on one another without in-
terstitial fine material; low linear ridges of compact
till without exceptional boulder accumulations; and
ice-contact deposits of sand and gravel, locally with
flowtill. The low linear ridges are alined with other
morainic features and lie at an angle to the trend of
bedrock units. The morainic deposits lie along a
somewhat sinuous, usually single line, but with a
generally uniform east-northeast trend. The Ledyard
moraine, however, splits into two parallel segments
east and north of Lantern Hill. Boulder accumula-
tions of stacked and piled boulders so spectacularly
displayed at a few places, particularly along the Led-
yard morainehare considered to have formed where
accumulations of bouldery till at the active ice-stag-
nant ice interface were washed by local ephemeral
melt-water streams. On the tops of some high rocky
ridges Where outcrops are abundant, the moraine is

38 GEOLOGICAL SURVEY RESEARCH 1975

identified by a greater number of dispersed erratics
than is usually found on such sites or by a low linear
ridge of till without bedrock outcrops. Heads of out—
wash are more or less alined along the moraines,
with some, usually fragmentary, coarse— to fine-tex-
tured ice-contact deposits of sand and gravel lying
north of the line of the moraine. This outwash is
considered to have been deposited by streams drain-
ing the zone of stagnant ice lying between the for-
mer active-ice interface and a new interface situated
to the north. Gaffney describes ice-shove features in
gravel deposits in the moraines and suggests that
the moraines represent slight readvances rather
than mere stillstands during ice retreat. Such re—.
advances are, however, probably, of little signifi-
cance. One would not expect an interface of live ice
with dead ice to remain completely static in position.

Four levels of glacial Lake Danbury, southwestern Connecticut

Mapping by W. B. Thompson showed that degla-
ciation of the Danbury—New Milford area (10c. 12)
resulted in the formation of glacial Lake Danbury,
which occupied the Still River valley and part of the
Housatonic River valley. Retreat of the ice front
opened successively lower spillways and resulted in
four lake levels. Glacial lakes also occupied the Dan-
bury Fairgrounds area and probably the Lake Can-
dlewood valley.

Triassic rock-derived drift east of the border fault, central
Connecticut

The restriction of Triassic rocks to the northwest
side of the border fault, which traverses the Glaston-
bury quadrangle (loc. 13), provides the basis for
some estimates of drift transport by continental
glacier ice and melt-water streams, according to sur-
ficial mapping by W. H. Langer, Reddish-brown till,
composed primarily of material derived from Trias-
sic sedimentary roéks, is common only within 2 km
southeast of the border fault, although local deposits
of reddish-brown till have been mapped as far as
6 km southeast of the fault. Stratified drift deposits,
however, include significant amounts of Triassic
material throughout the quadrangle, and material
derived from Triassic rocks has been reported ear-
lier by D. W. O’Leary (unpub. data, 1974) as far as
16 km southeast of the border fault in the Salmon
River valley in the Moodus quadrangle, Connecticut.

Preglacial bedrock weathering and pre-Wisconsinan weathering
of lower till, central and western Connecticut

Within the eastern Triassic border fault zone in
Somers, Conn. (loc. 14), a 3-m section of severely
weathered rock was excavated this summer in a
large borrow pit on the southeastern slope of an

 

18-m-high ice-streamlined bedrock hill. The weath-
ered rock is highly jointed breccia. Large pockets,
up to 1 m in diameter, are completely kaolinized,
containing fine-grained quartz masses up to 13 cm
in diameter. Many joint surfaces'are partly coated
with a soft pink mineral (montmorillonite?) and
(or) small semihedral to euhedral quartz crystals.
C. T. Hildreth found that rock exposed by excavation
on the northwestern side of the hill is fresh, and
unweathered bedrock caps the hill. Apparently, the
severe weathering is preglacial, and this small area
survived glacial scouring because of its sheltered
position in the lee of the bedrock hill. The feature is
a large-scale example of cragLand-tail morphology.

Preglacially weathered marble from the Inwood
Limestone, near Danbury, makes up a large portion
of clasts in both the uppenand the lower till (Scha-
fer and Hartshorn, 1965), according to W. B.
Thompson. The upper (Wisconsinan) till has a total
carbonate content of 50 percent at one locality. Car-
bonate minerals have been leached from most ex-
posures of lower till. .

Weathering effects in the oxidized zone of the
lower till at Thomaston Dam, Conn. (10c. 15), have
been studied by B. D. Stone, using X-ray and thin
section techniques. Illite shows increasing expan-
sion by hydration upward through this zone, and
garnets are dissolved and coated by iron oxide rims.
Values of pH are as low as 5.5 in the oxidized zone
but are as high as 7 or greater in fresh till. These
results suggest that the altered zone may be the base
of a soil profile that predated classical Wisconsinan
glaciation. Correlation with Midwest till weathering
sequences is precluded because of the noncalcareous
nature of the lower till at Thomaston Dam and be-
cause of truncation byuthe last ice sheet.

Active-ice deglaciation of the Triassic Lowland, Massachusetts

Three types of evidence indicated deglaciation of
the western side of the Triassic Lowland, central
Massachusetts (loc. 16) , by an active valley ice lobe,
according to F. D. Larsen. The evidence is found in
the Easthampton quadrangle along the north-north-
east-trending contact of crystalline rocks of the New
England Upland on the west and reddish-brown
Triassic rocks on the east.

The stratigraphic evidence consists of reddish-
brown till overlying grayish-brown till along the
North Branch of the Manhan River 1.2 km south-
east of Loudville, 0.5 km east of the crystalline-
Triassic contact. The older grayish-brown till is in-
ferred to have been derived from crystalline rocks
and deposited during the glacial maximum by ice

REGIONAL GEOLOGIC INVESTIGATIONS 39

that moved south into the Triassic Lowland from the
New England Upland. The younger reddish-brown
till was derived from Triassic rocks and was de-
posited at the southwestern edge of an active valley
ice lobe just prior to ice retreat. Southwestern ice
movement is indicated by the reddish-brown color
of the till and southwest-trending striations.

Striations trending S. 75° W. at Loudville and S.
52° W. at a locality 3.5 km S. 20° E. of Loudville
indicate a radial movement of ice in the southwest-
ern part of the Easthampton quadrangle. These
striations and those in the northern part of the
Mount Tom quadrangle to the south form a distinct
lobate pattern that extends across the lowland from
Loudville to Mount Tom.

In addition, erratics derived from the Triassic
Lowland have been transported west of, and higher
than, the nearest Triassic rocks at the crystalline-
Triassic contact on the southeastern slope of Pom-
eroy Mountain. This occurrence is similar to the 2-
to 3-km-wide belt of erratics derived from Triassic
rocks that lie west of the crystalline-Triassic con-
tact in the Southwick quadrangle, Massachusetts-
Connecticut (Schnabel, 1971) .

Quaternary stratigraphy, Buzzards Bay, Massachusetts,

determined from seismic reflection

From a high-resolution seismic reflection survey,
J. M. Robb distinguished four sedimentary units
underlying Buzzards Bay, Mass. (10c. 17). He in-
ferred that nearly ubiquitous Holocene marine muds
overlie probable glacial outwash deposits, which in
turn overlie well-stratified sediments filling valleys
cut into probable glacial till. Some of the valleys ex-
tend from valleys cut into bedrock that crops‘ out

along the northwestern side of the bay. J

Glaciomarine deposits in northeastern Massachusetts l

Glacial outwash graded to a marine baselew‘el in

the Marblehead North quadrangle (Ice. 18) is not
found higher than 17 m above present mea sea
level, as maps completed by M. J. Carnevale showed.
To the north, work in the Merrimack River Valley
near Newburyport (loc. 19) by A. F. Shride s owed
large ice-contact glaciomarine deltas graded 0 an
upper marine limit of 27 to 30 m above present sea
level. A few maximum marine strandline features
such as wave-cut cliffs and berms occur at 0 just
above the 100-foot (30 m) contour. In the same area,
extensive sand plains at the 50-foot (15 m) cdntour
surface apparently represent extensive erosio and
deposition on grade with a lower, younger marine

baselevel. These evaluations provide a more complete
I
l

 

picture of postglacial crustal rebound along the New
England coast.

Distribution of lacustrine and marine sediments in southern

Lake Champlain

An EG&G Uniboom system was used to profile
205 km of track between Ticonderoga Bay and Split
Rock Point, NY. (loc. 20). Total sediment thickness
is least (10 m) south of the Crown Point Bridge
and greatest (165 m) between Barber Point and
Split Rock Point, NY. Several prominent acoustic
reflectors appear to be the same as those reported
to the north by Chase and Hunt (1972) and include
the approximate boundaries betWeen Lake Vermont,
Champlain Sea, and Lake Champlain sediments.
Those presently inferred to be of Lake Vermont age
range from 0 to 125 m thick, and those of more
recent age from 0 to 60 m thick. A prominent terrace
at 0 to 3 m above sea level (26 to 29 m below present
lake level) probably is due to erosion during a low
lake level stand during Champlain Sea or early
Lake Champlain time.

APPALACHIAN HIGHLANDS AND THE
COASTAL PLAINS

Conodont color alteration, an index to diagenesis of organic

matter

According to A. G. Epstein, J. B. Epstein, and
L. D. Harris (1974), mapping of conodont color
alteration by geologic system throughout the Ap-
palachian basin and laboratory experiments induc-
ing color alteration showed that (1) the sequence of
color change from pale yellow to black to white
found in field collections is the same as that pro-
duced by heating alone; (2) color alteration is
progressive, cumulative, and irreversible; (3) color
alteration is time and temperature dependent and
virtually independent of pressure; and (4) color
alteration in conodonts correlates well with fixed
carbon, vitrinite reflectance, mineral diagenesis, and
isopach data. The color alteration index of conodonts
is a valuable method for assessing thermal metamor-
phism because (1) it is rapid and inexpensive and
requires only standard laboratory techniques and a
binocular microscope; (2) conodonts extend vir-
tually intact into garnet-grade metamorphism, well
beyond the range of other organic indexes; (3)
conodonts are most abundant and most easily con-
centrated from marine carbonate rocks, whereas
phytoclasts are least abundant in and often absent
from these same rocks; and (4) vitrinite, one of
the main types of phytoclast, is limited to post-

40 . GEOLOGICAL SURVEY RESEARCH 1975

Silurian rocks, whereas conodonts extend into the
Cambrian.

Thermal effect on Triassic rocks by contact metamorphism

Triassic fluvial and lacustrine sedimentary rocks
in the Culpeper basin, Va. (loo. 1, index map), con-
sist chiefly of conglomerate, siltstone, shale, and
calcisiltite. According to K. Y. Lee, these rocks
were extensively metamorphosed in contact with
diabase. After deposition, they were monoclinally
tilted westerly and northwesterly; block-faulted,
locally folded, and synkinematically intruded dia-
base fissure flows emanated from near-surface dia-
base intrusions; and contact aureoles formed adja-
cent to the diabase. The progressive advance Of
thermal effects in the aureoles is characterized by
different mineral assemblages. Biotite--cordierite-
quartz spotted hornfels and hypersthene-quartz
quartzites represent arenaceous and argillaceous
sediments near diabase succeeded outwardly by cor-
dierite-quartz-andalusite spotted hornfels and the
appearance of chlorite, epidote, and quartz. Lime
garnet-diopside—tremolite—idocrase skarns form in
calcareous sediments. Subsequently, hydrothermal
alteration and copper and iron mineralization oc-
curred in the aureoles, diabase bodies, and fissure
flows during the late stage of diabasic magma dif-
ferentiation. The width Of the aureoles is generally
less than 1.6 km, but a Wider aureole was formed in
areas of soft sandstone and conglomerate in contact
with a large alkaline diabase mass.

Probable Miocene age for the Pensauken gravel in the
Delmarva Peninsula

J. P. Owens reported that dating the widespread
gravel sheets of the emerged northern Atlantic
Coastal Plain (loo. 2) has long been conjectural be-
cause of the almost total absence of fossil remains.
In the lower Delmarva Peninsula, however, one of
these gravel sheets (the Pensauken Formation) ap-
pears to interfinger with a thick sequence of inter-
bedded dark-colored clay, sands, and gravels.
Locally, these beds cOntain fossils that are latest
Miocene in age. On the basis of this relationship and
the regional relationship of this gravel sheet to
others in the same general area, it now seems that
most of the widespread gravels Of the northern
Atlantic Coastal Plain are Miocene or perhaps
earliest Pliocene in age.

Conodont geother‘mometry indicates slaty cleavage formed at
elevated temperatures

Reconnaissance field investigations in the Appala-
chian basin by J. B. Epstein and A. G. Epstein

 

STATES IN APPALACHIAN HIGHLANDS K
AND THE COASTAL PLAINS

New YORK

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KENTUCKY , /\.'.. - VIRGINIA

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using conodonts as geothermometers showed that
a temperature of about 200°C coincides with the
initiation of slaty cleavage. The color Of conodonts
changes from amber to black with increasing time
and temperature, as shown by experimental heating
and corroborated by the field studies. Overburden is
the cause Of increased-temperatures. The Martins-
burg Formation of eastern Pennsylvania (loc. 3),
with its well-developed cleavage, appears to have
reached about 300°C. These observations support
the argument that slaty cleavage develops under
metamorphic conditions.

Slumping reactivated in bluffs of Sandy Hook Bay, New Jersey

Slumping of considerable displacement renewed
in the pile of chiefly unconsolidated marine sedi-
ments in the Atlantic Highlands of New Jersey
(loo. 4) in late summer 1972, according to J. P.
Minard. Older slump blocks were mapped and de-
scribed by Minard (1969). During restudy, several
interesting aspects of the role of natural processes
and the influence of man on these features were re-
vealed. It was learned that One large block had
slumped as recently as 1972. This block had a sur-
face area of possibly 16 ha and may have included
as much as several million cubic metres of soil and
rock. The pre-1972 slumping probably was caused

REGIONAL GEOLOGIC INVESTIGATIONS 41
l

by a combination of factors such as a high wateir
table and undercutting of bluffs by waves and tidal
currents. The slumping renewed in-1972‘ involved la
land surface about 0.8 km long, up to 76 m wide, arid
possibly from 15 m to 61 m deep, a total volume of
perhaps 600,000 to 800,000 m3 of soil and rock. The
slump blocks may not have been recognized by
municipal planners or construction engineers; con-
struction of sewer lines and large buildings was
planned and undertaken at locations of definite po-
tential geologic hazards. Results of the study are
published (Minard, 1974). This slumping also prob-

ably involved a combination of natural factors but '

may have been more influenced by man’s activities
than_was the earlier slumping.

Tectonics and geochronology in the Piedmont of northeastern

Virginia

The Fredericksburg complex (Ice. 5), as defined
by Louis Pavlides and others (1974, p. 569), is a
tectonic unit that consists chiefly of schist and gneiss
that have been extensively intruded by felsic plu-
tons and dikes and sills. It is overlain on its eastern
side by Coastal Plain sediments; its western bound-
ary coincides with the first appearance (eastward)
of felsic dikes and sills. Recent mapping by Pavlides
near the Rappahannock River and west of Fred-
ericksburg, Va., has shown that the Fredericksburg
complex contains at least two mappable formations.
In its westernmost part the Fredericksburg com-
plex includes part of the Quantico Slate, which here
is a high-grade crystalline schist. The other forma-
tion is a biotitic hornblende gneiss that occurs in
the eastern part of the complex and conformably
overlies the Quantico. Although a few generally
poorly developed sedimentary features suggest that
the biotitic hornblende gneiss stratigraphically as
well as structurally overlies the Quantico, it is pos-
sible that the gneiss has been thrust above the Quan-
tico. Both the Quantico and the biotitic gneiss have a
pronounced foliation (8,) parallel to and generally
conformable with bedding (So) as defined by schis—
tose and gnei-ssic quartzitic layers within each for-
mation. Both So and S1 have been folded along
northeast-trending axes to produce a series of open,
upright, northeast-plunging folds with local axial
plane foliation (Sz). A gently plunging (10° to 35°)
lineation, which is ubiquitous in the Fredericksburg
. complex, is parallel to the axes of some of these
folds.

The number of granitic dikes and sills increases
from west to east across the Fredericksburg com-
plex, as does the grade of metamorphism, from

 

staurolite in the west to sillimanite in the east. A
microcline granite gneiss with two foliations occurs
in the northeastern part of the Salem Church quad-
rangle and the southeastern part of the Storck
quadrangle and is herein named the Berea pluton.
This pluton appears to be a generally concordant
intrusion within the biotitic hornblende gneiss,
which it also locally crosscuts near its contact. A
weak foliation (S1) defines its general structural
concordance with the folds of the enclosing gneiss.
Well-developed, steeply dipping, northeast—trending
biotite folia define the regional foliation (82) of
this pluton, which is concordant with the 82 of the
enclosing gneiss. Zircons separated from one locality
in the microcline granite gneiss of the Berea pluton
and analyzed by T. W. Stern give the following
nearly concordant ages by use of the most recently
ascertained half lives: 2°“Pb/238U yields an age of
346.8 m.y., 2°7Pb/235U yields 348.6 m.y., and 2"PW
206Pb yields 360.6 m.y. These ages indicate that the
youngest regional foliation (S2) within the Berea
pluton and its enclosing country rocks is younger
than 360 my. and is a structure of Acadian age
or younger.

Palynology

According to L. A. ,Sirkin, studies of the pollen
and spores from a few localities in the barriers
cropping out at elevations near 24 m above sea level
near Charleston, SC. (loc. 6), showed these micro-
flora to have characteristic Tertiary (as evidenced
by the presence of Pterocarya) aspects rather than
Pleistocene aspects. Apparently, the Pleistocene sea
did not exceed this level in this area, although any
number of ‘authors have indicated that it did.

Abundance of Catoctin mafic dikes in Virginia indicates

scale of late Precambrian crustal distention

G. H. Espenshade reported that metadiabse feeder
dikes to the upper Precambrian Catoctin Metabasall
lavas are widespread in the older Precambrian plu-
tonic rocks and overlying metasedimentary rocks
(Lynchburg and Swift Run Formations) in the
northern part of the Blue Ridge anticlinorium (loc.
7). Continuous exposures in pipeline trenches in the
Rectortown quadrangle showed these dikes to be
far more abundant than surface exposures suggest.
The total thickness of dikes in a section of pipeline
trench 4.5 km long amounted to about 20 percent
of the total rocks; in another section of trench 1
km long, the dikes made up 15 percent of the total.
About 90 percent of the dikes are less than 15 m
thick; very few dikes are more than 30 m thick.

42 GEOLOGICAL SURVEY RESEARCH 1975

The great volume of Catoctin Metabasalt lavas and
metadiabase dikes in the Blue Ridge anticlinorium
was probably erupted during a period of continental
rifting in the late Precambrian _(Rankin, 1972). In
northwestern Newfoundland, very similar basalt
flows fed by dikes cutting the older Precambrian
basement are also judged to have been erupted
during a rifting stage, either in the late Precam-
brian or early Paleozoic (Strong and Williams,
1972). Some measure of the scale of crustal disten-
tion accompanying this continental rifting and
basalt eruption is given by the total volume of

feeder dikes. In the Rectortown quadrangle, crustal '

distention appears to have been on the order of 15
to 20 percent.

Gravity data indicate mafic body near District of Columbia

Gravity measurements in the District of Columbia
and Maryland (loc. 8) revealed a northeasterly
elongated gravity high with sharp gradients ac—
cording to D. L. Daniels. The anomaly, which is
5X17 km, extends from the center of Washington,
D.C., to College Park, Md., and may be caused by
a mafic body in the Piedmont rocks, here covered
by a thin veneer of Coastal Plains deposits. The body
is probably related to the so-called Baltimore Gabbro
Complex, as used by Herz (1951), which is on trend
to the north.

Prominent spheroidal features exposed by strip mining

Large spheroidal features in the highwall strata
of strip mines were noted by V. A. Trent during the
geologic mapping of the Anawalt quadrangle (Ice.
9) in McDowell County, W. Va. These features are
up to several metres in diameter, have a flattened
ellipsoidal to round shape, and occur in competent
and incompetent strata consisting of sandstone, silt-
stone, and shale of the Pocahontas and New River
Formations of Pennsylvanian age. These features
are most conspicuous near the tract of the axial
plane of the Dry Fork anticline, a major structural
feature in the area, and appear to be related to
jointing.

CENTRAL REGION AND GREAT PLAINS
KENTUCKY

Geologic mapping
A cooperative project with the State, begun in
1960, was more than 86 percent completed by May

1, 1975, when 512 geologic maps had been printed
(fig. 1), another 52 maps had been approved for

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FIGURE 1.—-Pub1ished geologic quadrangle maps (patterned
area) of Kentucky as of May 1, 1975; small .squares are
7%-min quadrangles.

publication, and an additional 45 were undergoing
editorial review. Geologic mapping was in progress
in 75 quadrangles. About 710. maps will be pub-
lished to cover 763 71/2-min quadrangles that are
wholly or partly within the State. The geologic
maps are printed on recent editions of topographic
base maps of quadrangles, at 124,000 scale, and
published in the geologic quadrangle map series.

Lithostratigraphy and depositional environments of the
Lexington Limestone

E. R. Cressman (1973) found that the Ordovician
Lexington Limestone of central Kentucky (10c. 1,
index map) consists of 11 complexly intertongued
members that are composed of fossiliferous and
bioclastic limestone and shale that were deposited in
a marine intralittoral zone of the Appalachian geo-
syncline. Transgression and regression of rock types
resulted from varying rates of subsidence that were
unrelated to the Cincinnati arch or the Jessamine
dome. Subsidence of the southern part of the area
during the later part of Lexington time may have
been the result of displacement along the Kentucky
River and the Irvine-Paint Creek fault zones. Ca1-
carenites of the Lexington contain an average of 2.4
percent P205 present as cryptocrystalline carbonate-
fluorapatite that occurs as fillings and replacements
of small fossils.

New data an eastern Kentucky coal resources

Mapping of low- to medium-sulfur coal beds in
southern Lawrence and northern Johnson Counties
Ky. (10c. 2), by P. T. Hayes, C. L. Pillmore, D. E.
Ward, D. C. Alvord, and C. W. Connor added to the
national coal resources in the proven and indicated
categories. Many well-known coal beds that are com-
mercially developed to the southeast thin toward
and within the mapped area. Although a few of
these beds are locally thick enough to be stripped,

REGIONAL GEOLOGIC INVESTIGATIONS

 
 
 

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' NORTH DAKOTA ‘
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L_ I MINNESOTA - .
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STATES IN CENTRAL REGION
AND GREAT PLAINS
they have little potential for large—scale underground
mining.

Geologic and hydrologic information for land-use planning in the

Kentucky River Area Development District

Experimental maps were prepared by W. L. Newell
and R. E. Davis largely from preexisting data for
the headwaters area of the Kentucky River (loc. 3) ,
eastern Kentucky, an eight-county region designated
the Kentucky River Area Development District
(KRADD) by the Appalachian Regional Commis-
sion. These maps have been presented to KRADD
planners in a format and terminology usable by 10-
cal people untrained in Earth science. Time and cost
limitations required a regional analysis with de-
tailed, large-scale examples of selected localities.

Most of the maps produced to meet these needs
show the abundance and distribution of naturally
occurring materials and the domain and intensity
of geomorphic processes. Three types of maps show-
ing current land use, slope, and flood-prone areas
present both basic and derived data directly appli—
cable to specific land-use decisions. Basic map in-
formation on quality and quantity of surface and
ground water, bedrock and surficial geology, and
mineral fuels can be interpreted for a wide variety
of current and potential uses.

Accompanying texts explain bedrock control of
geomorphic processes, distribution of surficial de-
posits, and hydrologic characteristics of the intense-
ly dissected eastern Kentucky terrane. Within this

 

43

conceptual framework, geomorphic processes and the
landscape can be evaluated in humanly significant
terms of low to high potential risk and thus indicate
the opportunities and limitations for land use.

MICHIGAN AND WISCONSIN

Preglacial topography

Research by geochemical methods in the Michigan
part of the Sault Ste. Marie 2° quadrangle (loc. 4)
to find areas that may have potential for economic
metallic and nonmetallic deposits was begun by J. W.
Whitlow and J. F. Windolph. A study of avail-
able data indicates an overburden comprising la-
custrine and glacial deposits up to 130 m thick. The
overburden locally is thickest near Lake Superior
and thins southward to a thickness of 64 m near
the north shore of Lake Michigan. Bedrock crops
out at many places and ranges from dolomite and
limestone south of lat. 46°20’ N. to sandstone and
minor quartzite north of lat. 46°20’ N. Bedrock out-
crops and available water-well data were used to
outline roughly the valleys and hill areas of the pre-
glacial topography, which had greater relief than
the present topography.

Paleomagnetic studies in Houghton County, Michigan

According to K. G. Books, results of preliminary
paleomagnetic determinations for rock samples from
Keweenawan lava flows at Silver Mountain and
Sturgeon Falls in Houghton County, Mich. (loo. 5),
showed a reversed polarity and a direction of rema-
nent magnetization similar to those in the South
Range lava flows near Ironwood as well as to those
in other Keweenawan rocks around Lake Superior.
This polarity and this direction of magnetization
are unique to lower Keweenawan rocks in the Lake
Superior area.

Archean volcanic pile, Wakefield area. Michigan

Metamorphosed volcanic rocks of Archean age
(Precambrian W) in the Wakefield area (loc. 6)
form a south-dipping monocline composed of older
andesitic flows and mafic to intermediate pyroclastic
rocks to the north and younger felsic schists and
pyroclastic rocks to the south. W. G. Prinz postu-
lated that these volcanic rocks represent the rem-
nants of the central and .upper parts of what was
once probably a much larger differentiated volcanic
pile. The andesitic flows in the Wakefield area are
similar to flows found in the central parts of more
completely exposed Archean volcanic piles in Canada.

44 GEOLOGICAL SURVEY RESEARCH 1975

The flows pass upward (southward) and westward
into felsic rocks typical of the upper parts of
Archean volcanic piles. Thickening of the felsic
schists to the west suggests that the Wakefield area
lies on the eastern side of a center of felsic erup-
tion. The western side of this center is cut oil? by
intrusive quartz monzonite. Basaltic flows typical of
the base of Archean volcanic piles are not exposed
in the Wakefield area; they may lie at depth to the
north or may have been removed by erosion prior
to deposition of overlying Precambrian X rocks.

Proposed repetition of strata by faulting, eastern Gogebic
County, Michigan, and north-central Wisconsin

Six northeast-trending units have been mapped
between Marenisco and Watersmeet in eastern
Gogebic County, Mich. (Fritts, 1969). The pre-
dominant lithologies in these units are (from north-
west to southeast) metavolcanic, graywacke, meta-
volcanic, graywacke, metavolcanic, and graywacke.
Iron-formation occurs in each volcanic unit and in
the southernmost graywacke unit. The units dip
steeply to the southeast, and the top directions, as
determined by graded bedding in the middle gray-
wacke and pillow structures in mafic flows in the
southernmost metavolcanic unit, all face southeast.
Fritts interpreted this as a thick conformable se-
quence forming a simple monocline.

C. E. Dutton traced the extensions of these units
as far as 72 km to the southwest into Wisconsin (10c.
7). He noted that the two oldest units, according to
Fritts’ interpretation, are free of granitic intrusive
rocks and are of low metamorphic grade, whereas
the postulated younger units are cut by intrusive
rocks and are of high metamorphic grade. Dutton
concluded that these six units do not represent a
continuous section. He suggested that the three
metavolcanic units are correlative, as are the three
graywacke units, and that they are repeated along
northeast-trending strike faults. The individual vol-
canic units are older and are overlain conformably
by the graywacke unit to the southeast, whereas the
middle and southern metavolcanic units are faulted
against the graywacke unit to the northwest. The
twofold metavolcanic-graywacke sequence is thus
repeated three times across the area.

In Wisconsin, the southernmost unit has been
folded along northeast-trending axes and intruded
along its southern limit by granite, accompanied by
the development of kyanite and, locally, staurolite in
schists formed from the graywacke.

 

MINNESOTA

Volcanic sedimentary sequences in the Vermilion district,

Minnesota

Two sequences of Precambrian W volcanic-sedi-
mentary rocks were distinguished by P. K. Sims in
the Vermilion district, northeastern Minnesota (10c.
8). The two sequences, which are separated by a
major dip-slip fault that has an estimated vertical
displacement of at least 1,000 m, differ in meta-
morphic grade and possibly are of different ages.

The sequence on the southern side of the fault is
weakly metamorphosed and has long been considered
the classical sequence of lower Precambrian rocks
in northern Minnesota. It consists of a lower mafic
volcanic succession (Ely Greenstone, about 6,500 m
thick) that is succeeded upward stratigraphically
by felsic volcanic rocks and volcanogenic graywacke-
argillite (Lake Vermilion Formation, about 3,000 m
thick, and Knife Lake Group, about 4,500 m thick).
A second younger mafic yolcanic succession (New-
ton Lake Formation, about 1,500 m thick) overlies
the Knife Lake Group. It contains numerous differen-
tiated mafic-ultramafic sills or flows as much as 200
m thick that have been interpreted by K. J. Schultz
(Univ. of Minnesota) as having been formed from
a magnesian basalt magma by crystal settling. The
ultramafic rocks at the base of the sills contain
about 5,000 ppm Cr; nickel concentrations associated
with the sills have not been found.

The sequence on the northern side of the fault
consists of amphibolite-facies volcanic and sedimen-
tary rocks and is associated with granitic rocks in
the Vermilion Granite—migmatite massif (Southwick,
1972). Geologic mapping by Sims in the Shagawa
Lake 71/g-min quadrangle near Ely has shown that
this northern sequence consists mainly of metamor-
phosed basaltic lava flows, some of which have dis-
cernible pillow structures, metagabbro, felsic tufi',
and graywacke-argillite. The oldest unit in the
Shagawa Lake quadrangle is a dacitic tufi' or flow,
which apparently was partially mobilized during the
Vermilion Granite magmatic episode. Because of its
physical appearance, trondhjemitic composition, and
intrusive relation to adjacent rocks, this rock unit
was earlier named the Burntside Granite Gneiss by
F. F. Grout (1926).

NEBRASKA AND KANSAS

Bedrock geologic map and thickness of Quaternary deposits

Data from test-hole logs, published and unpub-
lished maps, and field notes from the files of the

REGIONAL GEOLOGIC INVESTIGATIONS 45

Nebraska Geological Survey were used by G. E.
Prichard (USGS) and R. R. Burchett, E. C. Reed,
and V. H. Dreeszen (Nebraska Geological Survey) in
compiling a bedrock geologic map of-part 'of eastern
Nebraska and northernmost Kansas (10c. 9). Bed-
rock outcrops are shown. The map, which also shows
the combined. thickness of Quaternary surficial de-
posits of loe?ss, till, alluvium, and lake sediments, is
at a scale of 1:250,000. The map should be useful
for land-use planning and other activities such as
mining and water-well drilling.

ROCKY MOUNTAINS

Multiple ages of middle Tertiary mineralization in the western
San Juan Mountains

Potassium-argon and fission-track ages on vein
feldspars and micas, as well as on mineralization-re-
lated intrusions, indicated that middle Tertiary
mineralization in the Western San Juan Mountains
in Hinsdale County (loo. 1, index map) occurred
intermittently from about 30 to 10 my ago, accord-
ing to P. W. Lipman, F. S. Fisher, H. H. Mehnert, and
C. W. Naeser. This span is essentially the same as
that of the associated igneous activity.

MONTANA

WYOMING

I
l
l .14 .5
I COLORADO
I .1
: .6 |
I
I 18
7 o
I ' ‘
' I
ROCKY MOUNTAIN STATES I NEWIQMEXICO '
. . l
' I
| I
. _____l
I _ _ .I— '
L-

 

Mineralization recurred during the waning stages
of evolution of individual volcanic centers, including
several precaldera central volcanoes and also the
large Uncompahgre, San Juan, Silverton, and Lake
City calderas. Much of the richest mineralization,
localized within the Silverton caldera area, was em-
placed 5 to' 15 my. later than the time of caldera
formation about 27.5 m.y. ago, however, and appears
genetically unrelated to evolution of this caldera and
its associated magmatic system. This economically
significant mineralization seems most closely related
to volumetrically minor intrusions of quartz-bearing
silicic porphyry, an association that is also common

‘ elsewhere in the Rocky Mountain region.

STRATIGRAPHIC STU DIES

Ordovician sedimentation in the Western United States

R. J. Ross, Jr., found that Ordovician sedimenta-
tion in the Western United States was influenced
mainly by the changing position of the transcon—
tinental arch relative to the Earth’s latitudinal belts
and to sea level. Paleomagnetic studies have shown
that in Early Ordovician time the North American
Continent was near the equator and that the arch
was oriented east-west at about lat. 10° S. (McElhin-
ney and Opdyke, 1973). Carbonates of Tremadocian
and Arenigian Age south of the arch were mostly
dolomite, formed under shallow restricted water in
the horse latitudes (about 20° from the equator).
A gastropod-nautiloid fauna of low diversity in-
habited this environment. North of the arch, abun-
dantly fossiliferous limestone formed in well-circu-
late-d equatorial waters.

Late Arenigian (late Canadian) lowering of sea
level exposed older sedimentary rocks and crystal—
line rocks along the site of the arch and on the
Canadian Shield to extreme tropical weathering.
Quartz sand was released and swept westward south
of the transcontinental arch by the southern trade
winds to form the Everton Formation and parts of
the Simpson Group; as sea level rose, the transgres-
sive St. Peter Sandstone and sands of the upper part
of the Simpson Group were deposited.

North of the arch, the sand (Winnipeg Formation,
Swan Peak Quartzite, and Eureka Quartzite) was
swept westward by northern trade winds to over-
whelm the carbonate deposits on the platform and
shelf beneath .a prograding blanket. By middle
Caradocian to Ashgillian (Cincinnatian) time, the
source area of the sand on the Canadian Shale was
inundated.

46 GEOLOGICAL SURVEY RESEARCH 1975

As transgression reached its maximum, evapora-
tion of this enormous expanse of shallow sea caused
centripetal flow of normal marine surface water and
centrifugal flow of hypersaline bottom water. The
latter converted lime muds to dolomite. A gastropod
(Maclum'tes) nautiloid fauna characterized the re-
sulting facies. Sessile bottom—dwelling organisms
could survive only where surface water washed car-
bonate banks.

Dilution of the underflowing brines with normal
seawater caused the precipitation of dissolved silica
as chert to form the peripheral facies, which con-
tains graptolites and radiolarians.

Mississippian history of the northern Cordilleran region

In a synthesis of stratigraphy of the Mississippian
of the northern Cordilleran region, W. J. Sando
recognized two principal depositional cycles sepa-
rated by a cycle of epeirogenic uplift and erosion.
Each depositional cycle is divisible into phases that
represent significant changes in depositional pat-
terns. During cycle I (early Kinderhookian to early
Meramecian), predominantly carbonate and evapo-
rite deposition occurred on a broad cratonic shelf
bordered on the east by land and on the west by a
deep trough that received terrigenous sediments
from an adjacent western land mass. Kinderhookian
transgression was followed by regression during the
Osagean and early Meramecian. Regional uplift dur-
ing latest early Meramecian time (cycle II) drained
the shelf area and caused the sea to be_ confined to
the western trough. During cycle III (middle Mera-
mecian to Chesterian) the sea again transgressed

onto the craton, which was differentiated into the '

Big Snowy-Williston, Wyoming, and Uinta basins
and which received‘terrigenous and carbonate sedi-
ments. The Big Snowy-Williston basin was uplifted
during late-st Chesterian time and lost its identity,
but the Wyoming basin continued to expand into the
Pennsylvanian, when it engulfed most of the Cor-
dilleran platform and breached the transcontinental
arch.

Stratigraphy of southern Beaverhead Mountains, Idaho

G. F. Embree, R. D. Hoggan, E. J. Williams (all
of Ricks College) and Betty Skipp (USGS) (1975)
reported that a 3,000-m-thick incomplete sequence
of mainly miogeosynclinal Paleozoic rocks occurs in
the southern Beaverhead Range, Clark and Lemhi
Counties (loc. 2), where it is unconformably under-
lain by the Wilbert Formation (Precambrian Z) and
capped by a remnant of Triassic rocks. The Wilbert
Formation is more than 600 m thick and is over-

 

lain by as much as 30 m of Kinnikinc Quartzite
(Ordovician). Above the Kinnikinic, the Jefferson
Formation (Devonian) ranges from 0 to 65 m thick.
Thin, unnamed Upper Devonian and Lower Missis-
sippian shale, siltstone, and limestone unconforma-
bly overlie all older rocks and are gradationally over-
lain by about 1,000 m of limestone of the Middle
Canyon Formation (Mississippian). About 300- to
400-m-thick, intensely deformed massive limestones
of the Scott Peak Formation (Mississippian) over-
lie the Middle Canyon. Less deformed Mississippian
limestones of the South Creek and Surrett Canyon

, Formations locally overlie the Scott Peak and are

about 200 m thick. The uppermost Mississippian
formation, the Big Snowy, which is about 200 m
thick, is conformably overlain by Pennsylvanian
sandstone, which grades upward into Pennsylvanian
and Lower Permian alternating sandstone, limestone,
and dolomite totaling about 975 m in thickness. The
uppermost 95 m of the Paleozoic sequence is inter-
bedded chert and phosphatic limestone and shale of
the Phosphoria Formation (Permian).

Local eastern source for Pennsylvanian turbidites in Wood
River Formation, Idaho

Middle and Upper Pennsylvanian turbidite con-
glomerate and sandstone with an eastern source—
probably an emergent Copper Basin Formation (Mis-
sissippian) flysch terrane—are present in the east-
ernmost known exposures of the Wood River Forma-
tion in Blaine County, Idaho (loo. 3) (Skipp and
Hall, 1975). A folded and faulted thrust, the trace
of which trends about N. 20° W. for 9.6 km across
the Fish Creek Reservoir area, brings the Wood
River Formation over the Copper Basin Formation.
The Wood River Formation is more than 520 m thick
in the Fish Creek area. Turbidite conglomerate is
abundant only in easternmost exposures and is in-
terbedded with the typical fine-grained limy sand-
stone and sandy limestone of the Wood River in its
type area. General lithologies, faunas identified by
R. C. Douglass, and petrographic studies by J. N.
Batchelder showed that the conglomerate derived
from the, east occurs in stratigraphic sequences that
correlate with units 2, 3, 4, 5, and 6 (lower part)
of the Wood River Formation in the type area.
Conglomerates of unit 1, the Hailey Conglomerate
Member of the Wood River Formation, probably
have a different source than the local turbidites of
the higher stratigraphic units discussed here.

Stratigraphy of the Pierre Shale (Upper Cretaceous) in the
northwestern Denver basin

Recent investigations of the Pierre Shale (Upper
Cretaceous) in southeasern Wyoming and northern

REGIONAL GEOLOGIC INVESTIGATIONS 47

Colorado (loo. 4) by L. W. Kiteley (1975) provided
evidence that sandstone units previously assigned
to the Terry Sandstone Member are both older and
younger than the type Terry near Fort Collins, Colo.
The type Terry, so far, has not been traced on the
surface beyond its type locality. The sandstone that
is called Terry in the subsurface of the Denver basin
may be only partly equivalent to the type Terry.
Mapping of outcropping sandstone units at Francis
Ranch in southeastern Wyoming, which are younger
than Baculites jensem' and older than the Fox Hills
Sandstone, has demonstrated that these units range
in thickness from about 30 to 120 m and were de-
posited in shoreface and foreshore environments as
very fine to medium-grained sands. The correlation
of outcrops and well logs indicates that these sand-
stones are Widespread in the northern Denver basin.[

Comparison of the outcropping Pierre Shale at
Francis Ranch with laterally equivalent rocks in the
Denver, Hanna, Laramie, and Powder River basins
indicates that use of the names Sussex and Shannon
Sandstone Members of the Steele Shale, and Park-
man Sandstone Member of the Mesaverde Forma-
tion, when applied to rocks in the Denver basin,
should be abandoned. The Sussex and Shannon, at
the type sections'in the Powder River Basin, are
equivalent in age to the upper part of the Niobrara
Formation and overlying Gammon Ferruginous
Member (equivalent) of the Pierre Shale in the
Denver basin. The Hygiene Sandstone Member of
the Pierre Shale in the Denver basin is about the
same age as the Rock River Formation in the Lara-
mie Basin and the Parkman Sandstone Member of
the Mesaverde Formation in the Powder River
Basin. In the Denver basin, the name Hygiene Sand-
stone Member should be substituted for Shannon,
the name Terry Sandstone Member should be sub-
stituted for Sussex, and the names Rocky Ridge,
Larimer, and Richard Sandstone Members should be
substituted for Parkman.

Castle Rock Conglomerate extended

Separate studies by P. E. Soister and L. W. Mc-
Grew in the Denver basin (loc. 5) extended the
area known to be underlain by the Castle Rock Con-
glomerate of Oligocene age. Originally, much of the
Tertiary rock of the region was assigned to the so-
caJled Monument Creek beds and considered to be
Miocene (Hayden, 1874) or Oligocene (Darton,
1905). After Lee (1902) and Richardson (1912)
separated the Monument Creek beds into two forma-

 

tions—the Dawson Arkose of Eocene (later called
Late Cretaceous and Paleocene) age and the Castle
Rock Conglomerate of Oligocene age—the area be-
lieved to be underlain by Oligocene rocks was con-
siderably restricted (Richardson, 1915). Vertebrate
fossils collected during the recent work and identi-
fied by G. E. Lewis (USGS) and P. O. McGrew
(Univ. of Wyoming) showed that the Castle Rock
Conglomerate extends northeast from the area
mapped by Richardson (1915) to 40 km east of
Denver. Reconnaissance by both Soister and Mc-
Grew suggested that erosional remnants of the
Castle Rock Conglomerate extend 10 to 20 km south-
east of those mapped by Richardson (1915) .

Ammonite zonation of upper part of Lewis Shale, San Juan
basin

A study by W. A. Cobban, E. R. Landis, and C. H.
Dane (1974) of the ammonite faunal zones of the
upper part of the Lewis Shale of Cretaseous age
along the eastern side of the San Juan basin in Rio
Arriba County (loc. 6) confirmed the previously pub-
lished conclusions of J. E. Fassett and J. S. Hinds
(1971) that there is a southwestward increase in
the age of the top of the Lewis Shale across the
basin. The uppermost part of the Lewis Shale in the
Dulce area probably lies in the zone of Baculites
compressus, whereas in the Regina area about 80
km south of Dulce the uppermost part of the Lewis
lies several ammonite faunal zones lower.

Cretaceous stratigraphy. southern San Juan basin

The Borrego Pass Lentile (Upper Cretaceous) of
the Crevasse Canyon Formation (Correa, 1970)
can be differentiated from the overlying Mulatto
Tongue of the Mancos Shale in the southern part
of the San Juan basin in New Mexico (loo. 7), ac-
cording to J. F. Robertson. The differentiation is
based on lithologic character, depositional environ-
ments, and the separation of these formations by an
unconformity. The Borrego Pass, informally called
the stray sandstone, consists of very light gray,
very fine to medium-grained, well-sorted sandstone
and interbedded carbonaceous siltstone and shale
that were apparently deposited in a strand plain en-
vironment. Thin lenticular beds at the base of the
Mulatto Tongue, on the other hand, generally consist
of poorly sorted, calcareous, fine-grained to conglom-
eratic sandstone that contains fossil clam shells
and shark’s teeth and that grades in many places
into a hash of broken shells. ,

48 GEOLOGICAL SURVEY RESEARCH 1975

IGNEOUS STUDIES

Lower crustal and upper mantle nodules in the Ming Bar

diatreme, Big Belt Mountains

The Ming Bar diatreme penetrates a complexly
folded and thrusted sequence of sedimentary rocks
in the northern Big Belt Mountains of Montana and
was discovered by G. D. Robinson and M. E. Mc-
Callum during mapping of the Beartooth Mountain
quadrangle (loo. 8). The pipe contains nodules of
granulite, pyroxenite, and peridotite of probable
lower crustal and upper mantle origin. The matrix
is alkali olivine basalt of unusually magnesian com-
position and contains abundant megacrysts of olivine
and chrome diopside. The upper portion of the pipe
is choked with large foundered blocks of Cretaceous
sedimentary units, and material along the pipe mar-
gins is intensely brecciated and granulated.

Microprobe analysis of representative nodule and
matrix suites by D. H. Eggler (Geophysical Labor-
atory) permitted the determination of P—T equili-
bration values for mineral phases and thereby pro-
vided a basis for estimating depths of crystalliza-
tion. Pyroxene and spinel chemistry indicates that
granulites and pyroxenites are related to each other
and most likely originated in the lower crust. The
more magnesian peridotite assemblage includes
spinel lherzolite, harzburgite, and wehrlite and was
probably derived from an upper mantle source.
Olivine and chrome diopside megacrysts may also- be
accidental inclusions of mantle or may be cognate
to the magnesian basalt of the diatreme, which con-
tains phenocrysts that are chemically indistinguish-
able from the megacrysts. The wehrlite could also
be cognate to the basalt.

Eocene volcanic rocks in the Pioneer Mountains, Montana

Volcanic rocks, dominantly basaltic to latitic flows,
occur in the Pioneer Mountains, Mont. (loc. 9), and
nearby areas, where they are being studied by E-an
Zen. The presence of oxidized rubble and columnar
jointing shows the emplacement to be entirely sub-
aerial. Individual flows range from a few metres to
as much as 50 m thick, and the intercalation of flows
of different compositions and silica contents indi-
cates the simultaneous presence of magma chambers
from which these lavas were tapped. There are also
several ash beds consisting mainly of rhyolitic
pumice that include both water-laid reworked mate-
rial and air falls. Some pumice fragments contain
/ megascopic euhedral plutonic biotite, suggesting the
presence of a granitic magma body whose top bare-
ly breached the land surface. Most, if not all, latitic

 

and basaltic eruptions were through fissures (now
dikes) rather than discrete centers; how the magmas
of different compositions maintained their discrete
plumbing systems is a mystery. Five K-Af whole-
rock dates by R. F. Marvin and H. H. Mehnert are
from 46 to 49 my (lower and middle Eocene).
These volcanic rocks are thus contemporaneous with
the Lowland Creek Volcanics near Butte or the Ab-
saroka Volcanic Group east of the Yellowstone Park;
petrographically, they are vastly different, and the
flows may define a new volcanic field. The volcanic
rocks are emplaced after the last folding and thrust-
ing episodes in the area but are about synchronous
with the development of regional shear cleavage,
which affected some of the rocks, but elsewhere the
cleavage surfaces provided conduits for the lava.

Bimodal. rhyolite-basalt sequence on the northern margin of

the eastern Snake River ,Plain, Idaho

Raymond Jeanloz (Amherst College) and D. L.
Schleicher (USGS) (1975) mapped an unusually
Well exposed sequence of interlayered Pliocene to
Holocene rhyolite and basalt about 400 m thick at
Rattlesnake Point, 80 km northwest of Idaho Falls,
Idaho (10c. 10). A rhyolitic welded tuf’f <10 m thick
is intercalated with basalt flows that rest on Penn-
sylvanian limestones. Sources for the basalts include
three pyroclastic cones; a fine-grained gabbro plug
cuts one of the cones. A rhyolite flow about 3 km
across and 250 m thick caps the basalt flows and
cones. South of and topographically below the basalts
are three other rhyolite flow masses whose map
pattern suggests >130 m of displacement on a
steeply dipping east-striking fault.

The basalt flows intertongue northward with
coarse fan gravels, which overlie more steeply dip-
ping welded-tuff sheets, including the Edie School
Rhyolites of Scholten and others (1955). The inter-
tonguing suggests contemporaneous volcanism and
sinking of the plain relative to the surrounding
highlands.

The eastern Snake River Plain, a composite volcano-tectonic

depression

The eastern Snake River Plain (10c. 11) is a north-
east-trending volcano-tectonic depression of Pliocene
to Holocene age that cuts across earlier north-south-
and northwest-trending Laramide and Basin and
Range structures. Reconnaissance geologic mapping
and synthesis of available data by H. J. Prostka and
P. L. Williams indicated that the plain is a com-
posite feature whose formation began with caldera
collapse associated with major eruptions of rhyolitic
ash-flow tuffs. These events were followed by re-

REGIONAL GEOLOGIC INVESTIGATIONS 49

peated graben faulting and gentle warping inter-
spersed with renewed rhyolitic and basaltic vol-
canism as shown by progressively steeper plains-
ward dips of successively older volcanic units. North-
eastward migration of major rhyolitic volcanism
with time is indicated by progressively younger ages
' of basal ashTfiows tuffs in this direction.

Subsidence of the plain was accompanied by con-
tinued subsidence of marginal basins along reacti-
vated Basin and Range faults. However, relatively
greater subsidence of the plain itself along deep
graben faults is suggested by the concentration of
hot springs along both borders of the plain and by
the alined abrupt terminations of the Lost River,
Lemhi, and Beaverhead Ranges at the north edge
of the plain. The continued influence of Basin and
Range faults beneath the plain is suggested by the
alinement of many young basaltic vents and rift
zones on trend with major Basin and Range faults
outside the plain.

Basaltic volcanism and rift zones in the Snake River Plain

Basaltic volcanic eruptions in the eastern Snake
River Plain (10c. 11) are alined along rift zones,
which may be related, in part, to older structures
outside the plain, according to P. J. I. LaPoint. All
of the most recent eruptions (Craters of the Moon,
Wapi lava field, Hell’s Half Acre lava field) are as-
sociated with north- to northwest-trending rift
zones that are roughly parallel to Basin and Range
faults on the adjacent flanks of the plain. A broad
rift zone extends approximately 70 km west-north-
west from Island Park. Small flows, alined fissure
vents, small craters, and discontinuous fissures mark
the location of the rift zone. The rift zone is rough-
ly parallel to and approximately 25 km south of the
crest of the Centennial Range.

Future basaltic eruptions are more likely to occur
on the most recently active rift zones in the Snake
River Plain or on projections of active faults adja-
cent to the plain. ‘

Emplacement and deformational history of the Keystone Quartz

Diorite pluton, Wyoming

The Keystone Quartz Diorite of Houston and
others (1968) borders the western and southwestern
margins of the Lake Owen Mafic Complex of Stans-
rud (1962) in the southern portion of the Albany
quadrangle in Albany and Carbon Counties, Wyo.
(loc. 12). Although relationships of the quartz dio-
rite pluton with rocks of the layered mafic sequence
are uncertain, mapping by M. E. McCallum sug-
gested that the quartz diorite is younger than the

 

mafic complex. Gabbroic inclusions are abundant
locally, and several larger, irregular to lenticular
masses of gabbro are characterized by “intrusive
breccia” contacts where quartz diorite has clearly
invaded the gabbro. The gabbro and the quartz dio-
rite both may have been derived from the same
fractionating magma. Younger gabbroic and granitic
magma invaded the quartz diorite along planes of
primary foliation to form sills, some of which con-
tain intrusive(?) breccia that consists of felsic
material engulfing mafic fragments and blocks. The
latter hybrid sills may represent products of “mixed

. magma” crystallization. The sills were subsequently

folded; several granitic dikes cut across this “fold
fabric;” locally, Copper-bearing faults postdate the
dikes. .

Rawah batholith, a pluton of Boulder Creek age in northern

Colorado

A large pre-Silver Plume pluton emplaced into a
sillimanite-grade metasedimentary sequence was re-
cently recognized by M. E. McCallum in the Medi-
cine Bow Mountains of northern Colorado (10c. 13).
Its precise limits have not been established yet;
however, the pluton exceeds 965 km2 in area and
underlies the Rawah Range for which it has been
named. Batholith rocks range from quartz diorite
to granite, but the predominant rock type is a bio-
titic plagioclase-rich quartz monzonite that is locally
hornblende bearing. Appreciable assimilation is re-
flected by variation in bulk composition adjacent to
host-rock inclusions. Medium- and coarse-grained
equigranular rocks are most abundant; fine-grained
and porphyritic rocks also occur; the latter locally
have a rapakivi texture. Foliation is commonly well
developed and is mainly of cataclastic origin,
although alinement of tabular feldspars and biotite
along with schlieren and small inclusions in some
rocks is probably primary. At least two unrelated
major episodes of pre-Silver Plume cataclasis af-
fected these rocks. The first episode of cataclasis
(and in part protoclasis) apparently accompanied
and followed syntectonic intrusion associated with
the high-grade regional metamorphic events re-
sponsible for the sillimanite-facies metamorphism
and produced foliations roughly conformable with
those of deformed host rocks. The second cataclasis
occurred well after batholith emplacement and is re-
lated to shear zones.

Compositional, textural, and structural relation-
ships show similarities to those of plutons of the
1,700+ m.y. Boulder Creek Granite to the south.
Preliminary Rb-Sr whole-rock ages determined by

50 GEOLOGICAL SURVEY RESEARCH 1975

C. E. Hedge are approximately 1,710 my. and con-
firm a Boulder Creek age for the Rawah batholith.

Eocene porphyries in the Colorado mineral belt

Potassium-argon ages of biotite from monzonite,
quartz monzonite, and porphyritic quartz monzonite
collected by Bruce Bryant in Summit and Park
Counties east and southeast of Breckenridge, Colo.
(10c. 14), determined by Bruce Bryant, R. F. Mar-
vin, H. H. Mehnert, and C_. W. Naeser (1975) are
49.4:1.7, 43011.5, and 43.8:15 m.y., respectively.
These ages show that intrusion and mineralization
in that part of the Colorado mineral belt were of late
Eocene age. The intrusive rocks are younger than
the latest movements on the Williams Range-Elk-
horn fault system at the western margin of the
Front Range.

Fission-track ages of zircon, sphene, and apatite
from these rocks determined by Naeser are con-
cordant within the limits of analytic uncertainty,
but they are 5 to 10 my. younger than the K-Ar
ages.

Biotite from a bed of crystal tufi' about 1,500 m
above the base of‘ the Tertiary basin fill in South
Park is 58.41-20 my. old, an age comparable with
the K-Ar whole-rock age of 56.8-52.6 m.y. of an
andesite from near the base of the fill reported by
Sawatzky (1969). These deposits are folded and
overridden along the Elkhorn reverse fault by Pre-
cambrian rocks of the Front Range uplift.

STRUCTURAL AND GEOPHYSICAL STUDIES

Five distinct types of thrust faults in the eastern Holter Lake

region, northern Big Belt Mountains

Several types of thrust faults are well expressed
in the eastern Holter Lake portion of the Montana
disturbed belt (loc. 15). At least five distinct thrust
types were recognized from mapping by G. D. Robin—
son, W. D. Myers, W. H. Hays, and M. E. McCallum,
and these thrusts apparently reflect two dissimilar,
major, time-related styles of deformation. The first
and earliest deformational style is expressed by
shallow-dipping thrust sheets of large displacement,
some of which were folded during transport (type
1) and some of which were apparently folded mainly
or entirely after transport (type 2). Type 1 thrusts
are highly deformed (overturned and recumbent
traces are common), and plates are generally over-
ridden by the progressively younger, less deformed
type 2 thrusts [e.g., the Eldorado thrust in Upper
Holter Lake quadrangle (Robinson and others,
1969)]. The second and younger deformational

 

style is expressed by higher angle thrusts that are
concentrated primarily in a belt along the north-
eastern margin of the zone of thrusting. Some of
these faults cut plates of the older deformed sheets.
Included in the group of higher angle thrusts are
three types: (1) high-angle folded thrusts, (2)
imbricate, attenuated limb thrusts associated with .
overturned folds, and (3) postfolding high-angle
thrusts. Similar thrust types have been defined by
R. G. Schmidt in his work to the north and north-
west.

Thrusting in the Wood River area, Idaho

Mapping by W. E. Hall, Betty Skipp, J. H. Dover,
and J. N. Batchelder showed that allochthonous,
sheets of the Milligen and~Wood River Formations in
the Wood River area, Blaine.County, 'Idaho (loc. 3),
underlie an area 80 km long in a north-northwest—
south-southeast direction and 40 km wide. The Milli-
gen allochthon is composed of a 1,220+ m thick
sequence of tightly folded Devonian deep-water sili-
ceous marine elastic rocks that were thrust over a
gneissic dome complex in the Pioneer Mountains
and the flysch sequence in the Copper Basin Forma-

‘tion (Mississippian) . The Wood River allochthon lies

on the Milligen allochthon. Geologic studies indicate:

1. The Milligen Formation was tightly folded and
emergent before deposition of the Wood River
Formation.

2. The Wood River Formation was deformed into
broad open folds with north-south axes prior
to thrusting.

3. The Milligen and Wood River Formations were
thrust toward the northeast. Distal ends are
tightly folded and~overturned. Stratigraphic
separation is at least 3,000 m in the Wood
River allochthon with respect to the Milligen.
Amount of transport is estimated to be 48 km
for the Milligen allochthon and 16 km for the
Wood River allochthon.

4. The principal period of thrusting was probably
during the Sevier orogeny, although the Milli-
gen allochthon may have been involved in
thrusting during the Antler orogeny.

Origin of the Helena Valley

Recent geologic mapping by G. D. Robinson,
W. B. Myers, and R. G. Schmidt (USGS) and M?
L. Bregman (Univ. of New Mexico) established that
Helena Valley in northwestern Montana (loc. 16) is
bounded on the northeast by a major northwest-
trending normal fault of large displacement named
the Helena Valley fault. At the northwestern end
of the valley, rocks of the Spokane Formation of the

/ REGIONAL GEOLOGIC INVESTIGATIONS 51

Ravalli Group of the Belt Supergroup on the south-
ern (valley) side of the fault are dropped down
more than 1,000 m against rocks of the Greyson
Shale of the Ravalli Group of the Belt Supergroup
on the northern side of the fault. To the southeast
the fault is mostly concealed by deposits of Tertiary
and Quaternary age but is inferred to extend along
the base of a low range of hills at the northeastern
margin of the valley and along the base of the
Spokane Hills that border the valley on the south-
east. At the southeastern end of the valley the fault
appears to swing south of the Spokane Hills and
enter Townsend Valley, perhaps to end against
fault structures that border the western side of that
basin. Locally, along the base of the Spokane Hills.
the fault may displace sedimentary beds of Tertiary
age downward against rocks of the Belt Supergroup,
but this relation has not yet been fully substantiated.
The uniform eastward dip of Tertiary beds in the
eastern part of the valley suggests that they have
been downwarped along the fault. The presence of
the Helena Valley fault establishes Helena Valley as
a downwarped basin whose structure is broadly
similar to that of other downfaulted intermontane
basins in western Montana.

Dating a Laramide orogeny, northwestern Wyoming

The relatively short time involved in one major
mountain-making event of Laramide age and related
episodes of erosion and deposition in Teton County,
northwestern Wyoming (10c. 17), can be demon-
strated by structural and stratigraphic studies by
J. D. Love, pollen determinations by R. H. Tschudy,
and a K-Ar age determination by J. D. Obradovich.
These data and additional studies in adjacent areas
demonstrated the following succession of events, all
in Maestrichtian (latest Cretaceous) or late Cam-
panian time:

1. Deposition of 3,600 m of the Harebell Formation,
which contains many horizons of fossiliferous
marine or brackish-water sedimentary rock
and thick quartzite-boulder gold-bearing con-
glomerates in its upper half. Pollen of early
Maestrichtian to late Campanian Age occurs
below the conglomerate.

2. Uplift of the Washakie Range, a fold that ex-
tends southeastward from Yellowstone Lake
for 120 km. The southwestern margin of this
fold is bounded by a thrust fault that puts
Paleozoic rocks on Upper Cretaceous rocks.

3. Erosion that accompanied and followed the up-
lifting until the Paleozoic core was exposed.

 

About 7,600 m of rock was removed from the
uplift before the next depositional event.

4. Deposition of the Pinyon Conglomerate, 1,220
to 1,525 m thick, laid down on an unconform-
ity across vertical and overturned, eroded
strata of the Harebell Formation on the east-
ern side of Gravel Peak. The basal part of the
Pinyon contains a 330-m-thick bed of biotite—
rich tufi' with a K-Ar age of 67:07 my. Late
Maestrichtian pollen is found about 400 m
stratigraphically above the tufl'.

Inasmuch as the Maestrichtian Stage began about

70 my. ago, all four events must have occurred dur-

ing a time span of about 3 to 6 my

Influence of Precambrian structural trends in the 'Rio Grande

trough

Preliminary interpretation by L. E. Cordell of
aeromagnetic maps of a large part of the Rio Grande
trough in central New Mexico (10c. 18) indicated
prominent intersecting northeastern and northwest-
ern structural trends in the Precambrian crystalline
basement. Precambrian structural grain appears to
have influenced the pattern of Cenozoic extensional
faulting along the trough.

Pleistocene faulting in the Rio Grande trough

Recent mapping by G. O. Bachman and M. N.
Machette demonstrated that faulting of Pleistocene
age has displaced the Llano de Albuquerque geo-
morphic surface near San Acacia south of the con-
fluence of the Rio Puerco with the Rio Grande (10c.
19). The Llano de Albuquerque surface thus ex-
tends southward into a local graben farther than
previously recognized. Recent K-Ar dating of basalts
by R. F. Marvin, H. H. Mehnert, and V. M. Merritt
indicated that the Llano de Albuquerque surface is
less than 1.1 to 1.3 my. old. Therefore, faulting of
this surface is much younger than 1 my. because
extensive caliche had formed on the surface before
faulting occurred. Correlation of the Llano de Albu-
querque surface is based on mapping and caliche
morphology.

GEOTHERMAL RESOURCE STU DIES

Hydrothermal and seismic activity in southwestern Montana

E. C. Robertson found that the hot springs in
southwestern Montana occur along three major
alinements, one of which, from Gradiner to Marys-
ville, coincides with earthquake epicenters (10c. 20).
Fault zones, rather than volcanic flows and igneous

52 GEOLOGICAL SURVEY RESEARCH 1975

intrusives, seem to control the locations of the hot
springs. Ground water circulates to a depth of about
4 km and is heated to 115°C, as estimated from its
silica content. The surface temperature and dis-
charge of the springs are constant, and thus a stable
supply is provided for resort use; however, the
temperatures of the water are too low for the
springs to be a geothermal power resource. In-
creased depth of circulation owning to the head of
water at the recently built Canyon Ferry Dam
might enhance movement on a nearby fault.

Well drilled in Raft River valley, Idaho, hits hot water

A flow of about 2,000 l/min of water at 147°C
was produced from an initial-discovery ERDA well
completed in the Raft River valley (loc. 21) early
in 1975. The discovery resulted from coordination
of integrated geologic (Central Environmental
Branch), geophysical (Regional Geophysics
Branch), and hydrologic (Water Resources Divi-
sion) exploration begun a year and a half earlier
by the USGS. Drilling of additional boreholes now
is in progress.

Known occurrences of thermal water of about
100°C in the southern Raft River basin are located
near the intersection of the north-trending faults
and the Narrows structure, a northeast-trending
linear feature with regional geophysical expres-
sion, probably a basement shear, that passes through
the southernmost Jim Sage Mountains. Nearly coin-
cident with this structure is a concealed northeast-
to east-northeast-trending fault through the Nar-
rows that separates widely different structural
styles in the Salt Lake Formation and is expressed
by gravity and resistivity. North-trending faults do
not cross this structure.

The drill site for RRGE 1 was selected near the
intersection of the Narrows structure and the north-
trending Bridge fault; the well was predicted to
intersect the Bridge fault and produce hot water
at or below a depth of 1,400 m; actually, the fault
zone and flow of water were encountered between
depths of 1,240 and 1,320 m. Seismic and resistivity
studies predicted that basement rocks would be en-
countered in the well at a depth of about 1,600 m;
actual depth to basement is 1,375 m. The seismic
study showed low-velocity basement under the well
site, probably owing to fractured rock, and this
proved to be the case.

 

BASIN AND RANGE PROVINCE
STRATIGRAPHIC AND STRUCTURAL STUDIES

Distribution and economic potential of lower Miocene rocks in
the Goldfield Hills, Nevada

Lower Miocene volcanic rocks, mainly trachyan-
desitic and rhyodacitic flows and tufl's, host the ma-
jor epithermal precious-metal deposits at Goldfield
and Tonopah, Nev. Mapping in the Goldfield quad-
rangle and the south half of the Mud Lake quad-
rangle (loo. 1, index map) by R. P. Ashley showed
that most of the lower Miocene volcanic rocks in
the Goldfield Hills came from a center about 8 km
in diameter that occupies the central and topo-
graphically highest part of the Goldfield Hills, the
Goldfield mining district being at its western edge.
On the eastern side of the Goldfield Hills, the rocks
of this center interfinger with several flows that may
be from another center, perhaps from the Cactus
Range, 10 to 20 km farther to the east. A smaller
volcanic center, with vents concentrated in an area
probably only a few kilometres in diameter, is
located about 15 km north-northeast of Goldfield.
Only the rocks in the relatively large volcanic center
near Goldfield are strongly fractured and extensively
altered and thus have good potential for epithermal
ore deposits. Rocks on the eastern side of the Gold-
fields Hills are unaltered except for an altered area
of 1 km2 that contains a low-grade gold prospect.
This prospect, however, is located on the Northern
Nellis Bombing and Gunnery Range. The small vol-
canic center north-northeast of Goldfield shows little
fracturing and hydrothermal alteration, and thus
potential for epithermal deposits there seems low.

Allocthonous Paleozoic rocks in south-central Idaho

Dominantly allochthonous rocks underlie about
2,500 km2 in the Pioneer Mountains region (loc. 2)
of south-central Idaho. J. H. Dover, S. W. Hobbs,
W. E. Hall, F. S. Simons, C. M. Tschanz, and R. J.
Ross, J r., recognized at least six major thrust
plates of Paleozoic sedimentary rocks, each with
its own distinctive stratigraphic sequence or struc-
tural-metamorphic style. Parautochonous(?) Pre-
cambrian gneiss and lower to middle Paleozoic shelf
sediments are exposed in only three structural
windows. Evidence is accumulating that major struc-
tures of Antler (mainly Mississippian) age have
been moved into the Pioneer Mountain area on large
thrust faults of Mesozoic age. Cumulative crustal
shortening of at least some tens of kilometres, and
perhaps as much as 150 km, is suggested by recon-
struction of early Paleozoic paleofacies and by the
extent and intensity of deformation within the
allochthons.

REGIONAL GEOLOGIC INVESTIGATIONS 53

I i
l I L_-——
I 6 | 10 'l
. .11 I 7 I
I.4 I I
\.8 NEVADA l ‘
\ l UTAH
\ I
\\ .1 i L—
\ '- -______
\ . 3 l
\\ F“ . I .
l \
‘ I
' 'I
X ARIZONA | NEW MEXICO \
II ' .
2 i '
\\ :9 __J—-——-—_

New interpretation of the Supai Group of the Grand Canyon,
Arizona

Revision of concepts regarding the paleogeog-
raphy, age, and correlation of the newly described
formations that constitute the Supai Group of Penn-
sylvanian and Permian age was proposed by E. D.
McKee. Paleontological data indicate that the Mor-
rowan, Atokan, Virgilian, and Wolfcampian ages
are represented in the Supai Group. Isopach lines
suggest that the Grand Canyon area (loc. 3) was an
embayment that extended eastward from the south-
ern Nevada seaway during much of Pennsylvanian
and Early Permian time. Periodically, this embay-
ment also was connected with the Sonoran geosyn-
cline to the southeast, the Paradox basin to the
northeast, or both. The complex stratigraphic pat-
tern and the tectonic record of positive and negative
elements in the Arizona-Utah region are clarified by
the isopach trends and by~fossil data.

Geologic hazards in Washoe Valley, Nevada

Long-term geologic hazards in Washoe Valley,
- Nev. (loo. 4), can result from seismic shaking, flood-
ing, and landsliding. Recent mapping by R. W. Tabor
and S. D. Ellen of the very large Slide Mountain
landslide, first described by Thompson and White

 

(1964), indicated that the deposit includes at least
eight major debris flow events. The earliest debris
flow deposits are probably pre—Tahoe in age—that
is, older than approximately 60,000 yr—and the
youngest deposits may be less than 500 yr old, as
indicated by a C14 age of 630:200 yr for carbonized
wood from beneath the fourth major debris flow
mapped in the sequence. The debris flows appear to
originate in highly fractured granodiorite distrib-
uted in a wide zone along the eastern Sierra Nevada
frontal fault system. Considerable hazards may still
exist at the mouths of canyons beneath this shattered
rock.

Patterns of Cenozoic volcanism in Nevada

A complex pattern of changing volcanism with
time was revealed by a synthesis of data from the
newly completed Preliminary Geologic Map of
Nevada. This synthesis by J. H. Stewart and J. E.
Carlson indicates that volcanic rocks ranging in
age from 43 to 34 my consist of ash-flow tuffs and
andesitic to rhyolitic lava flows in northeastern
Nevada and of andesitic to rhyolitic lava flows and
sparse ash-flow tufl’s in a broad, poorly defined belt
trending east-west across central and eastern Ne-
vada between lat 38°30’ and 40°30’. The east-west
belt of lava flows is apparently a westward con-

' tinuation of rocks of similar age and character in

Utah. A large percentage of volcanic rocks ranging
in age from 34 to 17 my consist of ash-flow tuffs
and occur in an irregular belt trending west-north-
west and lying between lat 37° and 39° at the east-
ern border of Nevada and between lat 38° and 40°
at the western border. This belt extends into Utah
on the east and into the Sierra Nevada region of
California on the west. Volcanic rocks less than 17
my old are extensively exposed in northern, west-
ern, and southern Nevada. Of particular importance
in this age bracket are rocks consisting dominantly
of ash-flow tuffs that are exposed in an east-west
belt between lat 36°30’ and 37 °30’. This belt extends
into the Sierra Nevada region of California. It is
parallel to and overlaps the southern margin of the
ash-flow tufl" belt defined by rocks 34 to 17 my old.
One component of the complex pattern of Cenozoic
volcanism appears to be a southward migration of
volcanic activity from the belt of 43- to 34-m.y.-old
rocks in central and eastern Nevada to the belt of
rocks 17 my. old and younger in southern Nevada.

Tertiary sediments in eastern Elko County, Nevada

Examination by R. R. Coats of Tertiary sediments
in Elko County, Nev. (loo. 5), east of the longitude

54 GEOLOGICAL SURVEY RESEARCH 1975

of the Ruby Range, showed that most of them con-
tain a large component of silicic volcanic debris,
which suggests that they are younger than the
Eocene clastic and limy sediments of the Carlin-
Pinyon Range area, found by J. P. Smith and K. B.
Ketner to contain little or no volcanic debris. Most of
the Tertiary sediments in eastern Elko County are
directly underlain by poorly consolidated, nearly
horizontal tuffaceous sediments, presumably equiva-
lent to the Humboldt Formation of Miocene age, but
substantial areas of deformed and lithified tuffs and
tuffaceous sediments, presumably older, are also
present.

Age of the former Leach Formation in Nevada

Conodonts collected in the East Range of Nevada
by D. H. Whitebread from the former Leach Forma-
tion were identified as Ordovician in age by J. W.
Huddle and thus further support correlation of much
of the “Leach” with the Valmy Formation of north-
central Nevada. The section containing the conodont-
bearing limestones was tentatively included in the
Havallah sequence of Pennsylvanian to Permian age
by Stewart and Carlson ( 1974a) . A thrust fault with-
in the former Leach Formation separates this section
from a quartzite-bearing unit recognized earlier to
be equivalent to part of the Valmy Formation. The
former Leach Formation is not entirely of Ordovician
age, however, because locally some rocks formerly
included in the Leach are now recognized as part of
the Havallah sequence.

Possible new member of Oquirrh Formation in central Utah

Stratigraphic studies by H. T. Morris in two areas
in the southernmost part of the East Tintic Moun-
tains (loc. 7) in central Utah disclosed a possible
new member of the Oquirrh Formation that is
younger than any rocks exposed in the type area of
the formation in the Oquirrh Mountains. This se-
quence of rocks is about 1,675 m thick and contains
fusilinids of Virgilian and Wolfcampian age. It is
comparable to beds in .the uppermost part of the
Oquirrh Formation in the southern Wasatch Moun-
tains and is overlain by the Diamond Creek Sand-
stone.

Characteristics of active faults in the Nevada seismic zone
Investigation by R. C. Bucknam of the chemical
and petrographic characteristics of a volcanic ash
layer that is widespread in the near-surface alluvium
of Mineral County, Nev. (loo. 8), indicated that it
probably was erupted from Mono Craters, Calif.
Several C” dates of organic material associated with

 

the ash indicate an age of about 1,100 yr. Locally,
the ash represents a useful stratigraphic marker
horizon, and it serves to date the prominent fault
scarp in alluvium along the Wassuk Range south of
Hawthorne, Nev., at more than 1,100 yr old.

GEOCHEMICAL AND GEOCHRONOLOGICAL STUDIES

Geochemical anomalies in the Peloncillo Mountains; New Mexico

Geochemical maps showing the distribution of Cu,
Pb, Zn, Bi, W, Mo, and Ag in the central Peloncillo
Mountains, N. Mex. (Ice. 9), were compiled by A. K.
Armstrong, R. B. Carten, M. L. Silberman, and V. R.
Todd. Concentrations of anomalous copper, lead,
zinc, and silver occur within garnet-bearing meta-
morphic rocks adjacent to quartz monzonite por-
phyry, felsite, and latite porphyry dikes of middle
Oligocene age emplaced along the northwest-trend-
ing Johnny Bull fault and nearby parallel faults and
along the northeast-trending Preacher Mountain
fault where it intersects several northWest—trending
faults. Lesser, but still anomalous, concentrations of
metals occur in the dike rocks. Anomalous concentra-
tions of copper, lead, zinc,'and silver are also associ-
ated with lead-zinc replacement deposits near
McGhee Peak that are controlled by northeast-trend-
ing felsite dikes branching from a larger quartz
monzonite sill. Farther east, an anomalous zone of
lead, zinc, and silver at the Carbonate Hill mine oc-
curs within and adjacent to another large felsite
dike. At Granite Gap, anomalous concentrations of
base metals and silver are in small, largely oxidized,
hydrothermal sulfide veins in fractured limestone.
Smaller areas of anomalous copper, lead, and zinc
appear north of Granite Gap, where quartz monzon-
ite porphyry and latite porphyry dikes intruded and
metamorphosed the sedimentary rocks.

Trace-element ratio maps indicate a well-defined
zoning pattern with a relative enrichment of copper
along and near the Johnny Bull fault in the McGhee
Peak area and a relative enrichment of lead, zinc,
and silver farther east towards the Carbonate Hill
mine. Similar zoning patterns are found elsewhere
along the Johnny Bull and Preacher Mountain
faults.

Spatial association of the mineral deposits with
the quartz monzonite and latite porphyries and the
presence of a small outcrop of mineralized quartz
monzonite porphyry north of McGhee Peak suggest
that mineralization is related to the middle Oligocene
igneous event.

REGIONAL GEOLOGIC INVESTIGATIONS 55

Fission tracks record uplift of Wasatch Range, Utah

The time and rate of uplift of the Wasatch Range
(10c. 10), relative to the adjacent basin of the Great
Salt Lake, are recorded by fission-track dates, deter-
mined by C. W. Naeser, of apatites from Precam-
brian gneissic rocks exposed in the area near Ogden,
Utah, that is being mapped by M. D. Crittenden, J r.,
and M. L. Sorensen. Ages of apatites from the Boun-
tiful Peak area range from 9.6: 1.9 m.y., collected at
9,334 km, to 72.6:145 m.y. at 13,084 km. Apatites
collected at intermediate elevations have yielded in-
termediate ages. Apatites collected in Weber Canyon,
along an approximately level line, range in age from
5111.0 m.y. at the Wasatch fault to 18233.6 m.y.
near the easternmost exposures of Precambrian
rocks near Mountain Green, Utah. This eastward in-
crease of fission-track ages implies a pattern of up-
lift in which the range has risen along its western
side and has tended to pivot along its eastern side.
Two samples of apatites from Little Mountain at the
edge of Great Salt Lake west of Ogden gave fission-
track ages of 65: 6 my. and 73:7 m.y.

Experimental data indicate that fission tracks in
apatite are annealed by heating to 100°C for periods
on the order of 1 my These data cannot be inter-
preted to yield a single specific cooling history be-

cause the annealing process is dependent on both'

time and temperature; however, it is reasonable to
assume that the apatite dates record approximately
the time that the rocks passed through the 100°C
isotherm. When typical geothermal gradients are
assumed, it can be inferred that the rocks lay at a
depth of about 3,000 m at approximately the times
indicated. On that basis, the rocks Within the range
are assumed to have been uplifted on the order of
3,000 m in 7 to 9 m.y., or 330 to 430 m/m.y. In con-
trast, the rocks of the block beneath Great Salt Lake
have not been subjected to that degree of heating or
burial since approximately 70 my ago.

Age of basaltic dikes in the Roberts Creek Mountains, Nevada

Mapping by E. H. McKee showed that northwest-
trending dikes of basaltic composition make up about
15 percent of the surface outcrops in the northern
part of the Roberts Creek Mountains, Nev. (loc. 11) .
The anastomosing network of dikes is expressed as
a strong aeromagnetic belt in line with outcrops of
basalt flows exposed to the northwest. The dikes
yield a K-Ar age of about 16 m.y., which is the same
as the age of basalt flows to the northwest. These
basalts represent the oldest Cenozoic basalts in this
part of the Great Basin. The presence of basalt along

 

the belt suggests some sort of major rift features
related to the inception of Basin and Range
tectonism.

Submarine-sediment gravity flows

H. E. Cook and M. E. Taylor (1975) found that
the Cambrian and Ordovician rocks in the Basin and
Range province consist of basinal sediments in cen-
tral Nevada and shallow-water platform and broad
tideflat sediments in eastern Nevada. A wide variety
of allochthonous carbonate debris deposits occurs in
the basinal facies. This debris was transported basin-
ward by submarine-sediment gravity-flow mechan-
isms from upslope basinal and shoal-water carbonate
environments to the east. Fossil assemblages in these
allochthonous deposits are related to the North
American province, whereas fossil assemblages in
the in-place basinal lime mudstones and wackestones
bear no similarity, being related instead to the Asian
faunal province. One implication of large-scale im-
portance in reconstructing the geologic history of the
Cordilleran continental margin is that the in-place
basinal sediments containing the Asian fauna are not
simply part of a hypothetical crustal fragment left
behind after an Asian plate and a North American
plate collided and later separated. Rather, these in-
terbedded divergent faunas reflect fluctuations of the
boundary between two distinct marine environ-
ments: the North American continental platform
and adjacent ocean basin. Potentially similar rela-
tionships between other ancient faunal provinces
should be studied to avoid misuse of fauna] data in
paleogeographical reconstructions of lithospheric
plates.

PACIFIC COAST REGION

CALIFORNIA

Blueschist, quartz diorite, and quartz keratophyre in eastern
Klamath Mountains

Geologic mapping by P. E. Hotz in the McConaug-
by Gulch and upper Moffett Creek areas, northeast-
ern Etna and northwestern China Mountain quad-
rangles (10c. 1, index map), eastern Klamath Moun-
tains, Calif., revealed a belt of mafic and siliceous
phyllites and semischists and lawsonite-bearing blue-
schist that is exposed in a window of the Mallethead
thrust. The Mallethead thrust brings lower Paleo-
zoic(?) phyllites over sedimentary rocks of Ordo-
vician to Devonian age. Altered, brecciated quartz

56 GEOLOGICAL SURVEY RESEARCH 1975

.16

       

_—-

I

. I
WASHINGTON l

I

\

‘ ,,,--——»
_,.\_-

OREGON

diorite and quartz keratophyre occur in conjunction
with the phyllites and semischists. The quartz dio—
rite is probably the same as Lower Ordovician plu-
tonic rocks in the Gazelle-Callahan area to the east
(Potter, 1973; Rohr and Potter, 1973). The phyllites,
semischists, and blueschist have not been dated.
They are 20 to 24 km south and southeast of a previ-
ously reported (Hotz, 1973) belt of blueschist be-
tween serpentinite and an upper Paleozoic green—
stone-chert assemblage.

Magnetic anomalies may define former subduction zones

Interpretation of regional aeromagnetic data in
the Coast Ranges (loc. 2) of northern California by
Andrew Griscom, M. C. Blake, J r., and Isidore Zietz
showed that broad low-amplitude magnetic anoma-
lies over the Franciscan assemblage form lineaments
up to 150 km long along which are found small ser-
pentinite masses. It appears likely that the anoma-
lies may define mélange units and that detailed aero-
magnetic data may provide a way to map such units
more accurately.

The same investigators also noted two linear mag-
netic anomalies near Eureka, Calif., that trend
northeast and are interpreted to be oceanic magnetic
stripes within the subducted Gorda plate beneath

 

the Franciscan assemblage. The anomalies are at a
depth of approximately 8 km below the surface and
are 55 km east of the inferred location of the out-
cropping subduction zone at the base of the conti-
nental slope.

Paleozoic and Mesozoic contact in northern Sierra Nevada

Metavolcanic rocks exposed in the southwestern
part of the Berry Creek quadrangle (loo. 3), accord-
ing to Anna Hietanen, rest on Paleozoic (Permi-
an?) metasedimentary rocks and are continuous
with the Mesozoic metavolcanic rocks to the south.
Chemically, these rocks are similar to the Franklin
Canyon Formation (Devonian?) in the Bucks Lake
and American House quadrangles, but they are less
deformed and less thoroughly recrystallized. In many
outcrops, phenocrysts consisting of augite in meta-
basalt, of plagioclase in meta-andesite and metada-
cite, and of quartz in meta-sodarhyolite are well
preserved, undeformed, land have sharply defined
crystal faces. Outside the contact aureole of the Bald
Rock pluton, the ground mass is poorly recrystal-
lized. Tiny crystals of epidote, clinozoisite, amphi-
bole, and chlorite can be recognized only under a
high-powered lens. Fragments in volcanic ejecta and
amygdules are undeformed, in contrast to elongate
shapes of bombs, lapilli, and amygdules in most Pale-
ozoic rocks.

Structure and metamorphism of Franciscan rocks and their

relation to ophiolite in The Geysers steam field, California

An investigation of the structure of upper Meso-
zoic rocks that underlie The Geysers steam field of
northern California (loo. 4) by R. J. McLaughlin
revealed that these rocks form a 6- to 8-km-wide
southeastward-plunging antiform. The antiform is
flanked on the northeast and southwest by major
northwest-trending steeply dipping fault zones, and
its core is composed of complexly deformed and
metamorphosed marine sedimentary and volcanic
rocks of the Franciscan assemblage. Metamorphosed
Franciscan sandstones in the core of the antiform
exhibit a progressively higher degree of textural re-
constitution in the direction of the structurally high-
est rocks, and the sequential upward appearance of
the metamorphic minerals pumpellyite, lawsonite,
sodic amphibole, and jadeitic pyroxene indicates that
structurally higher sandstones were subjected to
increasingly higher presures during their meta-
morphism.

Ultramafic and mafic intrusive and extrusive rocks
interpreted to represent oceanic crust (ophiolite)

REGIONAL GEOLOGIC INVESTIGATIONS 57

overlie the Franciscan assemblage, and the lower
part of this ophiolite is in part sheared into the un-
derlying Franciscan rocks. Ophiolite in the south-
eastern part of the map area, near Mount St. Helena,
is offset right laterally along-the N. 40°—50° W.-
trending Geyser Peak fault a minimum of 8 to 10 km
from ophiolite exposed at Geyser Peak and Black
Mountain on the southwestern side of the fault. An—
other steeply dipping strike-slip fault to the south-
west of Geyser Peak and subparallel to the Geyser
Peak fault offsets upper Tertiary (Pliocene?) non-
marine strata and may be active.

Unconformity with the Sonoma Volcanics

Recent work by K. F. Fox, J r., documented the
existence of a major unconformity within the So-
noma Volcanics (Pliocene). These rocks form a
northwest-trending volcanic field 88.5 km long and
32 km wide located in the northern part of the San
Francisco Bay area, Calif. (loc. 5).

Rocks above the unconformity consist of a thick
sequence of ash flOWS (many of which are welded or
partially welded) and tuff‘, tuff-breccia, agglomerate,
and rhyolite that are locally capped by basalt flows.
These rocks form the northern half of the field and,
on the basis of dating‘ by earlier workers, are about
3 to 4 my. old. They have been collectively referred
to as the “Sonoma Tuff‘.”

Rocks below the unconformity form the southern
half of the field. They are geographically divided by
intervening alluvium-floored tectonic valleys into
three linear, northwest-trending blocks. They consist
chiefly of basalt or andesite, With subordinate inter-
layered ash flows and rhyolite flows, in contrast to
the predominantly tuffaceous rocks of the younger
part of the field to the north.

Remnants of redwood forests that grew on ash
flows directly above the unconformity at the base of
the Sonoma Volcanics are preserved at the locally
famous Petrified Forest.

The structure and stratigraphy of the volcanic
rocks are of interest to bay area environmental ge-
ologists because the field overlaps four important
northwest-trending fault systems: the Green Valley,
Maacama-Carneros, Healdsburg-Rodgers Creek, and
Tolay faults.

Amino-acid dating of marine terraces

The lack of a widely applicable technique for dat-
ing geologic materials in the 40,000- to 1,000,000-
yr.-B.P. range has been a serious stumbling block in
many aspects of Quaternary research. In the past 5

 

yr, research by P. E. Hare (Carnegie Institute of
Washington), John Wehmiller (Univ. of Delaware),
Etta Peterson and K. A. Kvenvolden (Ames Re-
search Center), and J. L. Bada (Scripps Institute of
Oceanography) has demonstrated that racemization
ratios of amino acids in some fossil materials can be
used to estimate geologic ages in this time range. A
joint project involving scientists from Ames Re-
search Center and the USGS was set up in late 1973
to investigate the reliability and applicability of this
potentially useful dating technique. C. M. Went-
worth, D. P. Adam, E. J. Helley, and K. R. Lajoie
(USGS) supplied known-age samples of wood, bone,
tooth, and shell for an initial feasibility study.
Racemization analyses of seven amino acids in these
samples by Peterson and Kvenvolden yielded encour-
aging results. In general, the racemization ratios in-
creased with the age of the sample, but several
glaring discrepancies existed, and it was apparent
that data from different types of samples could not
be directly compared. A more tightly controlled ex-
periment was set up to remove some of. the uncertain-
ty in the first set of analyses.

Lajoie and R. H. Wright selected a suite of fossil
gastropod and pelecypod shells from emergent ma—
rine terraces between San Francisco and San Diego
to investigate (1) variability among different taxa,
(2) variability among numerous specimens of the
same species from the same outcrop, (3) variability
in one species from the lowest emergent terrace over
a broad range in latitude, and (4) systematic varia-
tion with age in one species going up a flight of ter-
races. Peterson’s initial results on this second suite
of samples indicated that thick-shelled aragonitic
mollusk shells yield the most reproducible and rea-
sonable results.

Analyses by Wehmiller and Peterson on an ex-
panded suite of pelecypod samples from the emergent
marine terraces confirmed that racemization ratios
of amino acids from gastropods are significantly
different and far less consistent than those of amino
acids from pelecypods of the same age. These differ-
ences are due in part to contamination of the more
fragile gastropod shells analyzed and in part to a
significant taxonomic effect on racemization rates.

The geologic correlations and age estimates de-
rived from the amino-acid data provide critical ind
formation for other studies such as coastal tectonics
recorded in emergent marine terrace deformation.

Racemization ratios for eight samples of pelecy-
pods from the lowest terrace in the Santa Cruz area

58 GEOLOGICAL SURVEY RESEARCH 1975

have a reproducibility of i 10 percent, which is simi-
lar to values obtained from multiple analyses on fos-
sils from several localities along the southern Cali-
fornia coast.

Preliminary results of these feasibility studies in-
dicate that'racemization ratios of fossil mollusks will
be very useful for correlating and dating late Pleisto-
cene events. Tentative geologic conclusions can be
drawn from the results obtained to date. Similar
racemization ratios in fossils from the first (lowest)
emergent terrace at Afio Nuevo, Santa Cruz, Cayu-

cos, Newport Beach, and Torrey Pines and from'

the second terrace on San Nicolas Island correlate
these widely separated wave-cut features. The esti-
mated amino-acid age of 140,000i50,000 yr for this
group of terrace remnants is in close agreement with
U-series coral ages of 130,000i30,000 yr for the
Cayucos terrace (Veeh and Valentine, 1967) and
>87,000:F_12,000 but <120,000:t20,000 yr for the
second terrace on San Nicolas Island (Veeh and
Valentine, 1967 ). Slightly higher mean racemization
ratios in samples from southern California are inter-
preted to be the effect of slightly higher tempera-
tures (due to lower latitude) during diagenesis.

Different racemization ratios in fossils from the
first terraces at Goleta and Huntington Beach indi-
cate that these two terrace remnants do not corre-
late with those listed above. Slightly lower ratios at
Goleta yield an estimated age of 60,000i20,000 yr,
and significantly higher ratios at Huntington Beach
yield an estimated age of 300,000-160,000 yr.

Racemization ratios in fossils from the fifth (122
m) and the tenth (244 m) terraces on San Nicolas
Island are successively higher than those at.Hunt—
ington Beach and yield estimated ages of 0.4 my.
and 0.6 m.y., respectively, which agree with the
>200,000—yr U-series coral age of the ninth (221 m)
terrace (Valentine and Veeh, 1969) .

Kinetic studies and several tightly controlled field
experiments are presently being organized to at-
tempt to reduce the age-estimate uncertainties and

extend the range of the technique to late Pliocene
time.

Age of San Francisco Bay

E. J. Helley and B. F. Atwater finished radiocar-
bon dating of the Holocene marine transgression of
San Francisco Bay (loo. 6). Modern estuarine water
first entered the Golden Gate and reached the vicini-
ty of the proposed southern crossing between 9,600
and 9,300 radiocarbon years ago. The San Mateo-
Hayward crossing was reached at 8,400 yr BR, and

 

the vicinity of the Dumbarton Bridge was reached
at about 6,200 yr B.P. The environments of deposi-
tion of the radiocarbon dated cores are being ana-
lyzed to allow determination of the tidal level rela-
tive to the radiocarbon dates. This analysis will allow
construction of a sea-level curve for San Francisco
Bay.

New northeast-trending active fault discovered in San
Francisco Bay region

Field studies by D. G. Herd indicated that the Las
Positas fault is a zone of steeply dipping imbricate
fractures extending from the southeast corner of
Livermore Valley sputhwestward 14 km to near the
San Antonio Reservoir in La 'Costa Valley. Pliocene
and Pleistocene Livermore gravels and Pleistocene
and Holocene alluvium northeast of Arroyo Valle
are downthrown on the northern side of the fault.
Southwest of Arroyo Valle, Tertiary marine sedi—
ments are in fault contact with northeast-dipping
Livermore gravels.

Sediments of the Tassajara Formation (Pliocene
or Pleistocene) and Livermore gravels were de-
formed during the late Pliocene or early Pleistocene
into a series of northwest-trending folds in Liver-
more Valley. The units apparently tore with a scis-
sors effect at depth along the fault from the Jurassic,
Cretaceous, and Tertiary rocks of the Diablo Range.
Recent seismic activity and displacements in upper
Holocene alluvium indicate that the fault is still
active.

Landslides are expensive

At least 335 landslides have damaged manmade
structures in Alameda County, Calif. (loc. 6), from
1940 to 1971, according to a study by T. H. Nilsen,
F. A. Taylor, and E. E. Brabb (1975). About 85
percent occur on slopes greater than 15 percent.
Over $5 million worth of damage was caused by
landsliding during just one rainy season alone, 1968—
69. This cost averages to about $400 per developed
acre of land on slopes greater than 15 percent, or
about $100 per dwelling unit.

Chemical correlation of upper Cenozoic tuffs in California

A. M. Sarna-Wojcicki and others have been
working on a tephrochronology project, the purpose
of which is to correlate upper Cenozoic deposits in ‘
California. X-ray-fluorescence analyses of trace and
minor elements are being made by B. P. Fabbi
(USGS), neutron activation analyses are being run
by Harry Bowman (Lawrence Radiation Labora-

REGIONAL GEOLOGIC INVESTIGATIONS

tory) , and fission-track dating is being done by D. G.
Herd (USGS) . Noteworthy preliminary results to
date include:

1. The tuff in the type section of the Merced Forma—
tion south of San Francisco has been correlated
by means of trace- and minor-element chemis-
try with other tufi's within the San Francisco
Bay area, as well as with a tuif.320 km to the
north in the southern Cascade Range near
Mount Lassen pumice ash flow near Mineral,
Calif. A recent zircon fission-track date by
C. W. Naeser gives 1.1i0.4 my on the type
Merced tufi', confirming the chemical correla-
tion with the pumice ash flow near Mineral,
Calif. (K-Ar age of 1.1:05 m.y.). The age of
this tuff is important not only because it gives
a maximum age for faulting and folding of
Pleistocene deposits but also because the pres-
ence of this water-transported tuff in the Mer-
ced Formation dates the inception of Great
Valley drainage across the central Coast
Ranges in the vicinity of the San Francisco

Bay area and thus provides an important piece
of information on the paleogeography of the
bay area and the Great Valley.

2. Recently, computer analyses have been made of
chemical data on tephra and other silicic vol-
canic rocks from upper Cenozoic volcanic
source areas in California, as well as on wide-
spread ashes and tuffs deposited in sedimen-
tary basins. The purpose of this project is to
identify the volcanic provinces from which
ashes and tufi's were erupted. In the case of
water-transported ashes and tufi's, this kind of
information may also provide paleogeographic
evidence (as in the preceding paragraph). Two
different computer programs have been used
to determine the degree of similarity between
silicic volcanic rocks. One program calculates a
similarity coefficient for each sample pair in
the group. The other is a cluster analysis with
dendrogram, which clusters samples into
groups of progressively greater difference by
means of the distance function or the correla-
tion coefficient. Preliminary results of this
study indicate that provincial chemical simi-
larities exist between the pumice ash at Fri-
ant, the Bishop Tufi', Mono Craters, and Mono

Glass Mountain; all the above differ markedly
from the Inyo Craters. A thick, water-laid tufl’
in the Purisima Formation (Pliocene) of

59

provincial similarities with tephra of the
southern Cascade Range. This tufi‘ was proba-
bly transported by streams southward along
the ancestral drainage outlet of the Great Val-
ley to a marine basin west of the San Andreas
fault and was subsequently shifted northwest-
ward at least 180 km. Results of trace- and
minor-element analyses on another thick, wa-
ter-laid tufi‘ within the San Joaquin Formation
(Pliocene) in the 'Kettleman Hills indicate that
it is correlative with the Nomlaki Tufl" Member
of the Tehama Formation (K-Ar age of
3.4:04 m.y.) at Gas Point in northwestern
Sacramento Valley, about 540 km to the north-
west. If further verified, this correlation would
further support the conclusion that through
late Pliocene time the drainage in the Great
Valley was southerly, to a southwestern con-
nection with the ocean.

3. Samples of three different tufi's were obtained
from a core hole drilled by Earth Science As-
sociates for the Pacific Gas and Electric Com-
pany, in a foundation investigation study for a
proposed nuclear reactor site at Collinsville, in
the delta country just west of the Montezuma
Hills. Preliminary results of neutron activation
analysis indicate that the middle tufi’ is cor-
relative with the Lawlor Tuff north of Mount
Diablo, previously K-Ar dated at 4.0:02 m.y.
Correlatives of the other two tuffs have not as
yet been recognized.

4. Preliminary results of neutron activation analy-
ses indicate that one of the major ash-flow tufi‘s
in the Petrified Forest area of the Sonoma Vol-
canics, central Coast Ranges, is correlative
with a tuff in the Pliocene Rio Dell Formation
of Ogle (1953) at Cape Mendocino, near Fern-
dale. If further verified, this correlation would
be over a distance of about 250 km. The tuf’f at
the Petrified Forest has been K-Ar dated at
3.4 my, and this correlation would thus date
the tuff in the Rio Dell Formation.

Early Tertiary history of San Andreas fault

Paleogeographic reconstructions of lower Tertiary
deposits in the Gualala area (loc. 7), Santa Cruz
Mountains, and northern Gabilan Range by T. H.
Nilsen (USGS) and T. R. Simoni, Jr., and M. H.
Link (L.A. Harbor College), together with those of
the central Diablo Range, Temblor Range, and San
Emigdio Mountains, indicate the presence of an elon-

 

Santa Cruz Mountains, however, has strong

gate continental borderland in Paleogene California

60 GEOLOGICAL SURVEY RESEARCH 1975

that was emplaced by pre-Eocene right-lateral slip
along a proto-San Andreas fault. Large deep-sea
fans were deposited in isolated basins that were lo-
cated within and adjacent to the borderland. These
basins developed by extensional tectonic activity
characteristic of continental transform faults. The
modern San Andreas fault came into existence dur-
ing Miocene time and has been responsible for a total
of about 305 km of right-lateral offset.

Evolution of Panoche Valley

Field studies by T. W. Dibblee, Jr., indicated that
the Panoche Valley (loc. 8), about 70 km northwest
of Coalinga, is underlain by alluvium and Pliocene
and Pleistocene alluvial sediments. These presum-
ably rest on the beveled surface of the very thick
Cretaceous “Great Valley sequence” that overlies the
Franciscan complex of the Diablo Range to the west
and dips eastward through the Panoche Hils toward
the San Joaquin Valley to the northeast and south—
ward under the mountains to the south. Remnants of
the alluvial sediments on the crests of the Panoche
Hills, where they contain gypsiferous caliche of eco-
nomic value, indicate that these hills as well as the
Panoche Valley became part of the San Joaquin Val-
ley in Pliocene and Pleistocene time. Since that time,
the Panoche Hills were elevated, partly on the Orti-
galita fault system, to isolate Panoche Valley from
the San Joaquin Valley, and the mountains to the
south were elevated anticlinally and in part by
thrusting toward Panoche Valley.

Gravity changes, Pixley subsidence area

A repeat gravity survey by W. F. Hanna in a 13X
20-km region of the Pixley, Calif. (Ice. 9), sub-
sidence area indicates that tide-corrected changes in
observed gravity during the period 1969—74 are as-
sociated more with subsurface changes of mass than
with changes in surface elevation. The areally sys-
tematic gravity changes, which range from —0.04 to
+0.17 mGal, show very little correlation with subsi-
dence patterns but remarkably strong correlation
with the subsurface featheredge of the Corcoran
Clay Member of the Tulare Formation, a major con-
fining unit of underground aquifers. The main cause
of inferred increase of mass beneath the western
part of the area may be a watering of the uncon-
fined zone above the Corcoran, although elastic
volumetric effects in the underlying confined zone
cannot be dismissed. Refined interpretations by Han-
na and B. E. Lofgren will incorporate subsurface
compaction and water table data. Results are ex-

 

pected to apply to repeat gravity surveys made else-
where to detect elevation changes associated with
tectonic activity or with sediment compaction.

Cooling history of the eastern Transverse Ranges

About 110 40K—“Ar ratios were determined for
minerals from granitic rocks of the eastern Trans-
verse Ranges and southern Mojave Desert (100. 10)
by F. K. Miller and D. M. Morton. These ratios yield
ages that range from 55 my. to 122 my. Most co-
existing mineral pairs yield concordant ages, but
three lines of evidence suggest that none of the dates
is an emplacement age: ( 1) rocks known to be Pre-
cambrian yield Cretaceous ages on the basis of con-
cordant K-Ar dates from coexisting minerals; (2)
rocks from different parts of a single pluton yield
different apparent ages; and (3) biotite ages can be
contoured in a regular manner; the contours in no
way relate to the shapes of individual plutons.

The configuration of the biotite age contours is
interpreted to reflect the cooling history of the re-
gion. As a result, K-Ar ages from any rock in the
eastern Transverse Ranges or southern Mojave
Desert have little relation to age of emplacement,
and the age yielded by any sample is mainly a func-
tion of its geographic position.

The trend of the biotite age contours in the south-
ern Mojave parallels the northwestern structural
grain of the region. Northwest-trending biotite age
contours also exist in the northern part of the San
Bernardino Mountains but appear to be offset from
those on the Mojave by a system of reverse faults on
the northern side of the range. The trend of less well
defined age contours in the southern part of the San
Bernardino Mountains appears to be east-west,
parallel to the structural grain of the Transverse
Ranges.

Biotite age contours in the southern part of the
eastern San Gabriel Mountains appear to trend
about east-west, but enough data points are not
available as yet to contour the apparent ages
unequivocably.

Ground fissuring in part of the San Jacinto Valley, southern

California

According to D. M. Morton, ground fissuring is a
surface manifestation of subsidence in the San Ja-
cinto Valley (10c. 11), southern California. The sub-
sidence is occurring in a deep alluvial-filled graben
located between the Casa Loma and San J acinto
faults. Tectonic subsidence of the graben is estimated
at 0.3 to 0.6 cm/yr. Subsidence due to ground-water

REGIONAL GEOLOGIC

withdrawal is estimated at a maximum of 3.5 cm/
yr. Ground fissuring is occurring primarily on the
western side of a closed depression in the graben.
The area of ground fissuring has expanded from 1
km2 in 1953 to 12 km2 in 1974. Individual fissures
have attained-lengths of 850 m. The ultimate extent
of the ground fissures is not known.

Cenozoic tectonics of eastern Mojave Desert

Work in the Parker, Ariz., area and adjacent Cali-
fornia (loc. 12) by W. J. Carr and D. D. Dickey indi-
cated the virtual absence of active faults. The young-
est surficial fault activity appears to be of early
Pleistocene age. Absence of active faulting is sup-
ported by a lack of low-level seismicity and by the
subdued geomorphic expression of the basins and
ranges. The Tertiary structural, volcanic, and sedi-
mentary records suggest that major faulting in the
region ended about 14 m.y. ago. The Cenozoic struc-
ture of the area is one of persistent southwest-dip-
ping Tertiary rocks repeated by low to moderate
northeast-dipping faults. In the Whipple Mountains
these faults shoal out to join a major low-angle fault
of Tertiary age that involves Tertiary and Precam-
brian rocks. These structures can be interpreted as
having formed in an episode of major regional
strike-slip faulting.

Mylonitic rocks in the Peninsular Ranges batholith west of
the Elsinore fault zone

Preliminary results of detailed geologic mapping
in the Peninsular Ranges batholith in the Laguna
Mountains of eastern San Diego County (10c. 13) by
V. R. Todd indicated the existence of a zone (or
zones) of mylonitic rocks that roughly parallels‘ the
north-south to northwest regional structural grain in
this part of the batholith. Rocks showing varying de-
grees of dynamic metamorphism have been found in
a zone at least 24 km long and 12 km wide. Textures
seen thus far range from augen gneiss, in Which ex-
tensive recrystallization has accompanied cataclasis,
to ultramylonite. Mylonitization occurs in plutonic
rocks and in metaigneous( ?) gneiss and schist. The
intensity of cataclasis appears to vary in an irregu-
lar manner within a given area of mylonitic rock.
The mylonitic rocks are significant because younger
crush zones appear to follow zones of mylonitization.
At least one of these crush zones is the trace of a
fault with relatively young topographic expression.
As far as is known, this occurrence of mylonite is the
first reported in crystalline rocks west of the Elsi-

«t

INVESTIGATIONS 61

full extent of these rocks and their relationship, if
any, to mylonites east of the Elsinore fault.

OREGON

New breakdown of Applegate Group in southwestern Oregon

N. J Page reported that within the southern part

of the Medford 2° quadrangle (10c. 14), the Apple-
gate Group of Late(?) Triassic age can be broken
into five mappable units separated by tectonic boun-

daries: (1) meta-andesitic to metadacitic flows and
uffs interlayered with argillites, (2) metasedimen-
tary rocks with local lenses of metavolcanic rocks,
(3) metasedimentary rocks containing an abundance
of quartz-rich sedimentary rocks, (4) mélange con—
sisting dominantly of serpentinite and metasedimen-
tary rocks, and (5) mélange consisting dominantly
of serpentinite and metabasaltic rocks. The areal dis-
tribution of these rock units correlates well with the
distribution of aeromagnetic highs (metavolcanic
rocks) and lows (metasedimentary rocks). The
highs show some correlation with the broad distribu-
tion of known mineral occurrences.

Complex terrane along northwestern border of Josephine
peridotite in southwestern Oregon

Detailed studies by R. A. Loney and G. R. Himmel-
berg along the northwestern border of the Josephine
ultramafic complex in southwestern Oregon (10c. 15)
showed that the Vulcan Peak alpine-type peridotite
is a harzburgite body that has been intensely de-
formed and recrystallized at high temperatures in
the upper mantle before being thrust at low tempera-
tures against the high-grade metamorphic and igne-
ous complex to the north and then against the low-
grade Dothan Formation to the west (Himmelberg
and Loney, 1973).

The complex consists of intensely folded amphibo-
lite and ultramafic rocks of unknown age that are
intruded by hornblende gabbro of Late Jurassic age.
The oldest rocks are the amphibolites, which are
thinly foliated rocks of mainly andesitic composition
that have undergone metamorphism of the amphibo-
lite facies. The less deformed, younger ultramafic
rocks consist of intensely recrystallized clinopyrox-
enite, wehrlite, and dunite that contain relict cumu-
late textures. Such clinopyroxene—bearing cumulates
are lacking in the Vulcan Peak peridotite and seem
also to be lacking in the Josephine ultramafic com-
plex as a Whole. They do resemble basal sections of
cumulate gabbros in some ophiolite complexes, but

 

nore fault. Further field studies should determine the

the presence of amphibolite negates this resem—

62 I GEOLOGICAL SURVEY RESEARCH 1975

blance, and the fragmentation by the intrusive gab-
bro makes further comparison difl‘icult. The horn-
blende gab'bro commonly shows a marked gneissic
magmatic flow structure; its chemical composition is
similar to that of tholeiitic basalt.

WASHINGTON

New age determinations from the Okanogan Range

New K-Ar age determinations from six localities
representing four plutons that occupy an area of
1,300 km2 or more in the central Okanogan Range
(10c. 16) were recently obtained by C. D. Rinehart
and K. F. Fox, Jr., and showed minimum ages of
about 81 to 108 my Discordance in the ages of min-
eral pairs is least (3 percent) in the youngestpluton
and greatest (13 percent) in the oldest. Three of the
plutons are partly nested and successively younger
inward, and their relative ages are well established
from field relations. The youngest (81 my.) of the
three plutons is also the youngest thus far dated in
the range. Four mineral pairs from the older plutons
show much overlap, although the oldest age (108
my.) is also from the pluton whose intrusive rela-
tions show it to be \the oldest. Of the ages of the
three plutons, those of both the oldest and the young-
est corroborate fairly well the radiometric ages of
these units reported by Menzer (1970, p. 576, 577),
although he reported a Rb-Sr age of 129 my. from
the intermediate unit. Farther north, a single biotite
age of 98 my. was obtained from a sample of the
Cathedral batholith, agreeing well with a 94-m.y.
age reported by Hawkins (1968, p. 1789) .

Thus the number of plutons known to be dated in
the Okanogan Range is increased to nine; the oldest
—the Loomis (Rinehart and Fox, 1972, p. 4446)—
is 194 my.

lntracanyon flows of Yakima Basalt along the Snake River,

southeastern Washington

Isolated remnants of at least five intracanyon
basalt flows occur along the Snake River for 160 km
between Devils Canyon and a point 12 km upriver
from Asotin, Wash. These flows partly fill an ances-
tral Snake River Canyon eroded more than 300 m
into the Yakima Basalt. The flows were once con-
sidered early Pleistocene in age, but D. A. Swanson
and T. L. Wright (USGS) and the late Richard
Clem (Whitman College) interpreted them to be in
the upper part of the Yakima Basalt on the basis of
K-Ar dates and similar chemical and petrographic
characteristics. The youngest flow extends eastward

 

from Devils Canyon for at least 85 km. The two flows
of intermediate age occur along most of the 160-km
distance and are correlated with the Pomona and
Elephant 'Mountain Flows of the Yakima on the
basis of chemistry, petrography, paleomagnetic po-
larity, and the presence of a distinctive vitric tuff
that underlies and forms a peperite with the Po-
mona. The oldest flow and the least known flow may
extend from Devils Canyon upriver for at least 50
km and 150 km, respectively. Sources‘for the flows
are unknown, but unusually thick flow remnants near
Asotin, interpreted as lava dams that blocked the
ancestral Snake River Canyon, suggest proximity to
vent areas for the Pomona and Elephant Mountain
Flows. Imbricated gravel of metamorphic, plutonic,
and basaltic derivation underlies several remnants
and indicates a westward gradient for the ancestral
Snake River Canyon. Canyon cutting began about 13
to 15 my. ago during an eventful period of regional
subsidence, changing magma chemistry, and decreas-
ing rate of magma production. The intracanyon flOWS
were erupted during several successive stages of
canyon development, after most of the regional sub-

sidence but before significant deformation of the

Lewiston downwarp and other folds east of the
Saddle Mountains.

ALASKA

Significant new scientific and economic geologic
information has resulted from many field and topical
investigations in Alaska during the past year. Dis-

‘ cussions of the findings are grouped under seven

subdivisions corresponding to six major geographic
regions and a general statewide category. Outlines
of the regions and locations of the study areas are
shown on the accompanying index map of Alaska.

GENERAL

Alaskan Mineral Resource Assessment Program

The Alaskan Mineral Resource Assessment Pro-
gram (AMRAP), authorized by Congress to begin
in 1974, calls for an accurate appraisal of Alaska’s
mineral endowment within 10 yr. A rapid assess-
ment of this vast and potentially mineral rich re-
gion is required both to plan a viable long-range na-
tional minerals policy and to assist in decisions on
Alaskan land use and development over the next
decade. The program is administered by H. C. Berg.

REGIONAL GEOLOGIC INVESTIGATIONS 63

 

  
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
  

66°

62°§

(

' St Mich 1 . Qt
W“
McGrath

  

60

 

58°

56°

        
   

156°

 

168° 162'

Because mineral appraisals of such remote and
little-known regions as Alaska are still largely ex-
perimental, the program begins with an interdisci-
plinary experiment to develop specific guidelines,
techniques, and products as a model for a statewide
mineral inventory. Called the Prototype Alaskan
Mineral Resource Assessment Program (PAMRAP) ,
this 2-yr program of reconnaissance geologic map-
ping and other field and laboratory studies will also
provide greatly improved mineral-resource informa-
tion for selected prototype study areas. Four
1:250,000-sca1e (1° X 3°) qu-adrangles totaling 71,225
km2 are undergoing resource appraisal under
PAMRAP. The second (statewide) phase of the pro-
gram is called AMRAP and is simply the long-range
continuation of PAMRAP. AMRAP began on July 1,
1975, and will continue for approximately 10 yr.
Nine 1:250,000-scale quadrangles, totaling about
121,729 km”, tentatively are scheduled for resource
appraisal in the next 2 yr under AMRAP.

Alaska geothermal study
As part of a statewide study to assess the geo-

150°

70'
68"

Location of study ,
area or feature
discussed in text

66°

RE GI ONS
Northern 64 .
West-central
East-central
Southern
Southwestern
Southeastern

aspen?

62°

100 200 MILES

o
, Z 100 o
100 200 KILOMETERS ,60"

100 O

       

58°

56°

54°

 

  

144

Smith completed reconnaissance geologic mapping
of the calderas of the Alaska Peninsula between
Katmai National Monument and Unimak Island in
the eastern Aleutian Islands. The distribution of ash
flOWS surrounding the calderas has been determined,
and laboratory studies are continuing on their com-
position and age. These studies, the first to be done
on most of these calderas, should provide general
understanding of the volcanic history of these erup-

tive centers.

Gravity anomalies associated with igneous rock units in
southeastern Alaska

D. F. Barnes completed gravity traverses along all
the shorelines of southeastern Alaska, and the re-
sulting series of 1:250,000 simple-Bouguer-anomaly
maps reveals some important correlations between
lithologic units and the gravity field. Earlier recon-
naissance and marine gravity surveys had shown
that the dominant feature of the gravity field is a re-
gional gradient from positive anomalies along the
western coast of the archipelago to a low of about
—100 mGal along the Canadian border (Barnes,

 

thermal potential of Alaska, T. P. Miller and R. L.

1972). The more detailed gravity data show that

64 GEOLOGICAL SURVEY RESEARCH 1975

this gradient is not constant but flattens out and is
locally reversed‘along a central belt that extends
from Lynn Canal through Clarence Strait. The posi-
tive anomalies along this belt are generally asso-
ciated with known mafic outcrops, the largest posi-
tive anomalies being associated with the Duke Island
Ultramafic Complex (Irvine, 1967) in the south and
the gabbro near Haines in the north, each of which
causes local gravity highs of 30 to 40 mGal. An
outer belt of positive anomalies follows the mafic
rocks on the western coast of Baranofl‘ Island, north-
ward through the entrance to Cross Sound and prob-
ably to the La Perusse intrusive, where no data
have been obtained.

A wide variety of anomalies is associated with the
granitic intrusives. Many are gravity lows, but an
equally large number are gravity highs, and the
differences may reflect the age and environment of
the intrusive. For example, a marked gravity low is
associated with the Tertiary granitic intrusive near
Baranoif Hot Springs, but nearby intrusives of simi-
lar age and lithology appear to be gravity highs.

NORTHERN ALASKA

New graptolite discovery indicates Lower Ordovician rocks in
southwestern Brooks Range

A thin calcareous mudstone interval within the
thick metacarbonates of the Baird Group around
Hub Mountain, in the northwestern Baird Mountains
quadrangle, yielded a stratified and exceedingly well
preserved graptolite fauna (loc. 1, index map). The
new locality occurs on the southern edge of the car-
bonate terrane, about 38 km south of the original
graptolite locality (Tailleur and others, 1973). I. L.
Tailleur, W. B. Hamilton, and C. F. Mayfield(USGS)
and G. H. Pessel (Alaska Division of Geological and
Geophysical Surveys) collected two graptolite as-
semblages from mudstone beds within 5 m north of
a steeply dipping marble contact. Claire Carter iden-
tified forms indicative of Darriwillian (Middle Or-
dovician) and Castlemainian (Early Ordovician)
Ages in one of the collections and Bendigoni-an Age
(Early Ordovician) in the other.

Most of Early Ordovician and some Middle Ordo-
vician time seems to have been condensed into about
6 m of strata in which graptolites survived regional
metamorphism. Mudstone, interbedded black mud-
stone and carbonate, and light-colored carbonate be-
low the cbllections comprise enough thickness to ex-
tend the sedimentary record into Cambrian time,
nearly completing the Phanerozoic record for one of
the juxtaposed sequences in the western Brooks

 

Range. The thick Paleozoic carbonate section with
a thin interval of Lower and Middle Ordovician
basinal deposits nearly duplicates the coeval section
in the York Mountains on Seward Peninsula.

Metamorphism in the southwestern Brooks Range

Continuing examination of field and petrologic
data from the Ambler River quadrangle and the
eastern half of the Baird Mountains quadrangle is
being carried out by C. F. Mayfield (USGS) on
rocks collected since 1955 by G. H. Pessel and R. E.
Garland (Alaska Division of Geological and Geo-
physical Surveys), by W. P. Brosgé, R. B. Forbes,
T. P. Miller, W. W. Patton, Jr., H. N. Reiser, and
I. L. Tailleur (USGS), and by a mining company
(10c. 2). Preliminary results indicate a belt of sedi-
mentary, volcanic, and plutonic rocks along the
southern edge of the Brooks Range (Pessel and
others, 1973a) up to 40 kmwide that has been rr
gionally metamorphosed'to the greenschist facies.
Pelitic schists contain quartz, albite, muscovite,
chlorite, and varying amounts of chlbritoid, calcite,
tourmaline, magnetite, and carbon. Metabasites con-
tain albite, chlorite, and sphene and occasionally
amphibole, epidote, calcite, pyrite, or magnetite.
Granitic orthogneisses contain quartz, potassium
feldspar, albite, muscovite, and minor amounts of
biotite, zircon, pyrite, or magnetite. Garnet-bearing
schist zones occur discontinuously within this belt in
the southeastern Ambler River quadrangle and the
northeastern and central Baird Mountain quadran-
gle. Retrograded glaucophane, suggesting an early
stage of high-pressure metamorphism, occurs in
metabasites and a few pelitic schists (Forbes and
others, 1973) within the garnet zone in the south-
eastern Ambler River quadrangle and is preserved
only in metabasites from the garnet zones of the
central and northeastern Baird Mountains quad-
rangle. A gradual decline of metamorphic grade oc-
curs both north and south of the schist belt, pumpel-
Iyite-grade metamorphism in scattered mafic rocks
trailing off to a terrane of virtually unmetamor-
phosed basaltic rocks and sediments.

At least two regional metamorphic events are in-
dicated by superimposed and widely divergent planes
of schistosity, both in thin section and in outcrop.
Potassium argon ages on muscovite for two samples
of quartz mica schist, one from the central Baird
Mountains quadrangle and the other from nearby
in the Selawik quadrangle, are 122:3.7 my. and
108.5:33 m.y., respectively. It is likely that these
ages date the waning stages of greenschist meta-
morphism in the area. This is in contrast to a 213-

REGIONAL GEOLOGIC INVESTIGATIONS 65

m.y. isochron from K-Ar dates on paragonite, which
Turner (1973) accepts as the age of the culminat-
ing metamorphic event in the eastern part of the
Ambler River quadrangle.

Light-colored orthogneisses scattered throughout
the metamorphic belt had a wide variety of compo-
sitions ranging from granite and syenite to quartz
diorite and diorite. Alkalic metaigneous rocks occur
as small stocks, plugs, and dikes exclusively in the
Kallari-chuk Hills of the central Baird Mountains
quadrangle. They exhibit a weak metamorphic tex-
ture even tho-ugh they are often enclosed by highly
schistose and garnetiferous country rocks, which
indicate their intrusion either at a late stage of the
last metamorphic event or after a strong metamor-
phic even but before a second weaker event.

Significant stratiform sulfide mineralization of
high-grade copper, lead, zinc, and silver occurs With-
in the garnet zone from the eastern Ambler River
quadrangle. Proven reserves are estimated in ex-
cess of $2 billion (C. C. Hawley, unpub. data, 1973)
with good prospects for finding additional reserves.
Mining companies consider the sulfides to be of vol-
canogenic origin.

WEST-CENTRAL ALASKA

Regional geologic controls of the gold deposits near Name

The strong areal localization of the gold placer
areas within the regionally metamorphosed terranes
of the central Seward Peninsula has been recog-
nized since the earliest geologic fieldwork 75 yr ago.
The additional association of placer areas with cer-
tain rock types has also been known. However, for
want of viable stratigraphy of the country rocks of
the region, the gross geologic controls to account for
the established empirical relationships could not ~.be
determined.

The combined results of both the early workers
and the more recent field investigations by C. L.
Sainsbury, C. L. Hummel, and others throughout
the central Seward Peninsula established the gen-
eral distribution of several gross suites of country
rocks and their northward trend north and south of
the eastward-trending Kigluaik and Bendeleben up-
lifts. But the major regional structures accounting
for their distribution and trend were not determined.

All previous work suggested that only in the
southwestern portion of the Seward Peninsula (loo.
3) are the exposure, character, and structure of the
metamorphic rocks comprising the bedrock ade-
quate to allow them to be subdivided and mapped
extensively and, thereafter, to be used to delineate

 

regional structural elements. These tasks have now
been largely accomplished by Hummel through-
out the 5,000-km2 portion of the southwest Seward
Peninsula that encompasses the most productive
placers on the entire peninsula, unmined placers of
high potential, and the lodes from which the placers
were derived.

Two placer belts, which have yielded the greatest
production and still contain the greatest potential
of the region, extend northward from Nome and
Solomon for approximately 50 km. Both belts are
now interpreted to coincide with the axial anticlines
that constitute deformed remnants of folds that once
extended northward across the entire central Se-
ward Peninsula; however, their central portions
were destroyed by and over the younger Kigluaik
uplift.

The main localization of the gold-quartz and base-
metal veins and the gold placers derived from them
were preferentially effected in the rocks making up
the cores of the anticlines where they were tran-
sected by major northeast-striking strike-slip faults
and by a coordinate but subordinate set of north-
west-striking lesser faults and fractures.

Southeastern Seward Peninsula

Reconnaissance studies by T. P. Miller of three
large granitic plutons in the southeastern Seward
Peninsula (loo. 4) showed that the Darby pluton
has well above average amounts of uranium and
thorium (11.2 ppm and 58.7 ppm, respectively), the
Kachauik pluton has average to above average uran—
ium and thorium (5.7 ppm and 22.5 ppm, respec-
tively) , and the Bendeleben pluton contains average
amounts of uranium and thorium (3.4 ppm and 16.7
ppm, respectively). These three plutons show com-
positional and textural differences indicative of dif-
ferent source materials and (or) crystallization his-
tories that may have controlled the distribution of
uranium and thorium.

New information on the Kaltag fault

Ground and aerial inspections of the Kaltag fault
between Tanana and Unalakleet were carried out by
W. W. Patton, J r., R. M. Chapman, George Plafker,
and W. E. Yeend (Ice. 5). No fresh breaks or other
evidences of modern activity along this part of the
fault were found. However, offset streams, ponded
drainages, and slice and shutter ridges of bedrock
and' gravel along the fault zone attest to significant
movement in Holocene time. Tilted nonmarine coal-
bearing deposits of probable late Tertiary age were
observed at three localities within the fault zone.

66 GEOLOGICAL SURVEY RESEARCH 1975

In the Melozitna quadrangle, blueschist facies
rocks were discovered in Precambrian(?) and Pa-
leozoic metamorphic assemblagesmorth of the fault.
These blue amphibole—bearing recks appear to rep-
resent the ofl'set extension of the blueschist facies
terrane in the Kaiyuh Hills (Forbes and others,
1971) and provide additional support for previously
published estimates (Patton and Hoare, 1968) of
about 140 km of right-lateral offset along this seg-
ment of the Kaltag fault since Cretaceous time.

EAST-CENTRAL ALASKA

The Mount Doonerak structural high

The southernmost Carboniferous rocks in the cen-
tral Brooks Range are in the northern Wiseman
quadrangle (loo. 6). Two distinct sequences, one on
the northern flank of the Doonerak structural high
and the other in the Savioyok synclinorium, pro-
vide distinct contrasts in depositional and structural
styles.

North of Doonerak, a relatively thin, autochtho-
nous sequence of elastic limestones and limy mud-
stones (Lisburne Group) overlies the thin Kayak
Shale, which, in turn, unconformably rests on lower
Paleozoic volcanic rocks that make up the structural
high. This sequence is similar to the one recently
mapped in the northeastern Brooks Range where
the Lisburne underlain by a thin Mississippian clas-
tic unit unconformably overlies strongly folded and
faulted lower Paleozoic rocks.

In contrast, the thicker Lisburne sequence in the
Savioyok synclinorium displays rapid facies changes
in a relatively short north-south distance. Light—
colored shelf dolomites dominate on the southern
flank of the basin, while deeper water dark lime-
stones and shales predominate on the north. In this
structure, the Lisburne and Kayak are underlain by
a thick sequence of Upper Devonian clastic rocks,
the more normal pattern for most of the central
Brooks Range.

Detailed fieldwork by H. N. Reiser and J. T. Du-
tro, J r., indicated that large-scale displacements are
not necessary to explain the occurrence of these
contrasting sequences in such close geographic re-
lation. Detailed lithologic and biostratigraphic study
of the Lisburne of these sequences by A.» K. Arm-
strong is continuing.

Mated metamorphic beds in southern Brooks Range

Previous work has shown that garnet and amphi-
bole rocks, including both blueschist and amphibo-

 

lite, occur in a zone about 10 km wide within the
pelitic schists that form the southern edge of the
Brooks Range in the southeastern part of the Am-
bler River quadrangle (Forbes and others, 1971;
Pessel and others, 1973b). Petrographic data have,
recently been compiled by W. P. Brosgé, H. N.
Reiser, I. L. Tailleur, R. B. Forbes, and C. F. May-
field (USGS) and by G. H. Pessel (Alaska Division
of Geology and Geophysical Surveys) for the adja-
cent Survey Pass, Wiseman, and Chandalar quad-
rangles (loc. 7) to be used in preparing a small-
scale metamorphic facies map of Alaska. These data
show that within the schists of lower greenschist
facies that characterize most of the southern Brooks
Range, a zone of garnet-bearing schist 5 to 15 km
wide extends eastward almost continuously for
about 340 km from the southeastern Ambler River
quadrangle to the northeastern part of the Chan-
dalar quadrangle. In the western 150 km of this
zone, chloritoid and biotite are also common, and
glaucophane was found every 15 or 30 km in sam-
ples from metasedimentary as well as mafic rocks.
Kyanite occurs east of the last known glaucophane
locality, in samples from the eastern Survey Pass
and western Wiseman quadrangles. In most of the
Wiseman and Chandalar quadrangles, glaucophane
and kyanite are absent in the garnet zone, chloritoid
is rare, and biotite is common, but at the eastern
end of the zone, glaucophane occurs again as almost
completely chloritized relics in retrograded amphi-
bole schist. Elsewhere in the zone, the glaucophane
is fresh to partly chloritized.

Granitic plutons crop out a few kilometres north
of the zone in the Survey Pass quadrangle where the
partially altered glaucophane and garnet and local
biotite in the western half of the zone indicate a
thermal overprint on an earlier high-pressure as-
semblage previously described in the southeastern
Ambler River quadrangle (Alaska Division of Geol-
ogy and Geophysical Surveys, 1973, p. 34—36). Gran-
itic plutons lie within the zone in the Chandalar
quadrangle, and the garnet-biotite assemblage in the
Wiseman and Chandalar quadrangles indicates that
most of the eastern half of the zone is the product
of low-pressure thermal metamorphism. However,
the rare occurrence of almost completely altered
glaucophane and garnet near the granite at the east-
ern end of the zone suggests that the high-pressure
assemblage may originally have extended through-
out the zone- In any case, it seems that a long, nar-
row zone of thermal metamorphism was either co-
extensive with or in linear continuity with a long,
narrow zone of high-pressure metamorphism.

REGIONAL GEOLOGIC INVESTIGATIONS 67

Age revision suggested for chert unit in the Kuskokwim

Mountains

A widespread unit of chert, with some interbedded
gray slate and slaty shale, that forms the northern
end of the Kuskokwim Mountains in the Kantishna
River quadrangle (loc. 8) was examined during re
connaissance geologic mapping by R. M. Chapman.
W. W_. Patton Jr. and W. E. Yeend. This unit, which
was originally outlined by H. M. Eakin (1918) and
designated as probably early Mesozoic in age, forms
a belt 16 to 26 km wide and about 72 km long that
extends southwest from the upper Zitziana River to
near Lake Minchumina.

The chert is predominantly medium to medium-
dark gray and, in minor part, varicolored and forms
prominent hills that generally range in altitude from
487 to 792 m. The chert outcrops and rubble weather
to various shades of light yellow, tan, and orange
and give the semibarren ridges a distinctive appear-
ance. The beds generally strike northeast and dip
steeply south to near vertical. No reliable estimate
of thickness can be made on the basis of present in-
formation, but probably the unit is at least 600 to
700 m in thickness. Complex folding is apparent,
and, in part, the section may be overturned; there-
fore, the unit is probably not as thick as might be in-
ferred from the width of the outcrop belt.

Provisionally, this chert unit is believed to be cor-
relative with a similar chert unit in the Dugan Hills,
about 80 km northeast and just north of the Tan‘ana
River. The chert unit in the Dugan Hills has been
identified by Péwé, Wahrhaftig, and Weber (1966)
as the upper part of the Nilkoka Group of Precam-
brian or early Paleozoic age. An early Paleozoic,
possibly Ordovician, age for both of these chert
units is most probable, based on recent regional in—
terpretations. The probably early Mesozoic age in-
ferred by Eakin (1918) for the chert unit in thr
Kantishna River quadrangle no longer seems ten-
able.

Vertebrate fossil discovery

A vertebrate fossil site discovered by F. R. Weber
on Canyon Creek in the Big Delta quadrangle (loc.
9) was examined by Weber, D. M. Hopkins, and
T. D. Hamilton. Bones of a small horse, Camelops,
bison, mammoth, Saiga, wolf, rabbit, and caribou ( ?)
from the same stream channel fill have been identi-
fied by C. A. Repenning. Although remains of these
animals are common in Alaskan Pleistocene deposu
its, they are seldom found in stratigraphic context,
and this find, probably the first authentic association
of Camelops, an extinct North American camel,

 

with Saiga, an extant Asiatic antelope, suggests the
mixing of major faunal types across the Bering
Straits land bridge, probably in late Pleistocene
time.

Mineral potential in the Big Delta B-1 quadrangle

Reconnaissance geologic mapping in the Big Delta
A-1 and B-1 quadrangles (10c. 10) by H. L. Foster,
F. R. Weber, and T. E. C. Keith indicated that gran-
itic plutons of the same type that appear to be re-
lated to copper-molybdenum mineralization in the
neighboring Eagle and Tanacross quadrangles ex-
tend into the Big Delta quadrangle, especially in the
vicinity of Tibbs Creek. Other metallic minerals in
the B-1 quadrangle include previously mined gold
and antimony and molybdenum.

Metamorphosed peridotite in southeastern Big Delta

quadrangle

Several small metamorphosed peridotite bodies
were found by H. L. Foster, T. E. C. Keith, and F. R.
Weber in the Big Delta quadrangle (loc. 11) dur-
ing reconnaissance geologic mapping. The ultramafic
rock is foliated and folded and has been subjected to
the same regional metamorphism as the surrounding
country rock. The ultramafic rocks appear to have a
different history than those recently described in
the Eagle quadrangle, with the exception of one
body in the Eagle A-6 quadrangle south of Mount
Harper.

The several separate small bodies originally may
have been part of one or more larger bodies that
were tectonically broken up and separated.

Mankomen Group (Pennsylvanian and Permian) revised

The Mankomen Formation was raised to group
rank in its type area, the Eagle Creek valley, by
D. H. Richter and J. T. Dutro, Jr. (10c. 12). Two new
formations are recognized. The Mankomen is under-
lain conformably by the Tetelna Volcanics, consist-
ing of massive volcanic flows and volcaniclastic rocks
of Pennsylvanian age. The Nikolai Greenstone of
Middle and (or) Late Triassic age rests unconform-
ably on the Mankomen.

Fusulinids in the lowermost volcaniclastic part of
the Mankomen are Pennsylvanian (Atokan) in age.
Fossils higher in the group range from Wolfcampian
to Leonardian and, possibly, Guadalupian age.

The Tetelna Volcanics reflect the development of
a late Paleozoic volcanic arc whose waning stages
are represented by the volcaniclastic rocks of the
lower Mankomen. Lithologies of the Tetelna-Manko-
men strata and the new age data suggest that this

68 GEOLOGICAL SURVEY RESEARCH 1975

are had become virtually inactive by Early Permian
time (Richter and Dutro, 1975).

SOUTHERN ALASKA

Depositional environments of coal-bearing group

According to I. F. Ellersieck and Clyde Wahrhaf—
tig, the Healy Creek Formation and Suntrana For-
mation below the number one bed are characterized
by crosscutting lenses of sand and conglomerate
that are not continuous along strike for more than
a few metres (loc. 13). The Suntrana Formation
above the number one bed and the Lignite Creek
Formation have repetitive fining-upward sequences
of sedimentation. Individual cycles in these forma-
tions consist of, from base to top, conglomerate,
coarse pebbly sandstone with lag accumulations of
pebbles, crossbedded sandstones, silty clay, and coal.
These idealized sequences are often truncated by an
erosional surface above which a new cycle begins.
Complete cycles range from 5 to 30 m thick.

Ultramafic rocks in the eastern Alaska Range

Regional mapping and petrologic studies by W. N.
Sharp and D. H. Richter indicated that the alpine
ultramafic rocks in the low greenschist facies meta-
morphic terrane north of the Denali fault in the
eastern Alaska Range (10c. 14) are confined to two
parallel, but possibly genetically distinct, narrow
belts. The belts, approximately 25 km apart, trend
N. 70°—75° W. and are transected on the west by the
Denali fault.

Ultramafic rocks along the 175-km-long northern
belt consist principally of intimately mixed serpen-
tinite and clinopyroxene-dominant serpentinized py—
roxenite, peridotite (wehrlite), and dunite. Rodin-
gite inclusions, sometimes with nephrite rims, and
chromite segregations are locally common. The host
rock for the entire northern belt is a phyllite-marble
sequence that has been locally converted to chrome-
spinel-bearing assemblages of magnesite, dolomite,
and wollastonite at the ultramafic contact. Ultra-
mafic rocks in the shorter southern belt are more
homogeneous than those in the northern belt and
consist principally of orthopyroxene-dominant ser-
pentinized peridotite (lherzolite) associated with
gabbro, hornblende gabbro, and anorthosite. Both
the mafic and ultramafic rocks occur within a se-
quence of metavolcanic and metavolcaniclastic
rocks; no evidence of thermal metamorphism is
apparent.

These briefly described features suggest that the
ultramafic rocks in the northern belt were injected

 

as a hot crystal mush along a major crustal frac-
ture, whereas those in the southern belt were em-
placed mechanically, and while relatively cold, into
a subducted volcanoplutonic arc.

Granitic plutonism and metamorphism in the eastern Alaska

Range

Evaluation of K-Ar mineral ages by D. H. Richter,
M. A. Lanphere, and N. A. Matson, Jr., indicated
that plutonic rocks in the eastern Alaska Range
(10c. 15) were emplaced in Late Pennsylvanian time
(282 to 285 my.) and during two distinct intervals
in Cretaceous time (105 to 117 my. and 89 to 94
m.y.). Development of a large plutonic-metamorphic
complex, consisting of diorite and quartz diorite in-
timately associated with banded gneiss and other
metamorphic rocks, apparently occurred during Late
Triassic to Middle Jurassic time (163 to 199 my) . A
smaller plutonic-metamorphic complex is Miocene
in age (17 m.y.).

The younger Cretaceous plutons are recognized
only in the regionally metamorphosed Devonian and
older terrane north of the Denali fault. Plutons of
the older Cretaceous and Pennsylvanian events are
restricted to Pennsylvanian and younger terrane
south of the Denali fault and are associated with
coeval volcanic rock assemblages. The major plu-
tonic-metamorphic complex is also restricted to the
terrane south of the Denali fault and may relate to
collapse of a late Paleozoic volcanic arc in Triassic
time, followed by syntectonic magmatism in the
Jurassic. The Miocene plutonic-metamorphic com-
plex may reflect the time of initial movement along
the Denali fault.

Genesis of Kennecott-type copper deposits

Detailed stratigraphic and petrographic studies
by A. K. Armstrong and E. M. MacKevett, Jr., of
carbonate rocks that host Kennecott-type copper
deposits, augmented by previous geologic studies,
indicated that sabkha processes were involved in
the ore gensis. The Kennecott deposits are local-
ized in the largely dolomitic lowermost 100 In of the
Chitistone Limestone (Upper Triassic) (loc. 16).
The lowermost 100 m of the Chitistone formed in
cyclic subtidal to supratidal environments and con-
tains abundant stromatolites, mud chips, and pseu-
domorphs of sulfate-bearing evaporites. This se-
quence disconformably underlies marine limestone.

The copper in the Kennecott-type deposits was
probably derived from the Nikolai Greenstone, a
thick, widespread subaerial succession of basalt
subjacent to the Chitistone that has an intrinsically

REGIONAL GEOLOGIC INVESTIGATIONS 69

high copper content. A hydrologic regimen during
which highly oxygenated water dissolved substan-
tial amounts of copper from the Nikolai and subse-
quently deposited the copper in the reducing en-
vironment of the sabkha is postulated. The present
configurations of the deposits may reflect some re-
mobilization and displacement during Jurassic or
Cenozoic tectonic and plutonic events.

Relations between Alexander and Taku-Skolai terranes in the

McCarthy quadrangle

Field investigations in the McCarthy quadrangle
(Ice. 17) by E. M. MacKevett, Jr., and D. L. Jones
provided additional data in support of the contention
that the Taku-Skolai and Alexander terranes, two
of the major subj-acent structural units of south-
eastern Alaska, eastern south-central Alaska,‘ and
nearby parts of Canada (Berg and others, 1973), are
juxtaposed by faulting.

The westernmost known extent of the Alexander
terrane—in the eastern part of the McCarthy quad-
rangle—is represented by the mid-Paleozoic Kas-
kawulsh Group (Canadian usage), which contains
locally fossiliferous marble and some schist and
amphibolite. These‘rocks are flanked on the north,
west, and south by 10cally metamorphosed upper
Paleozoic sedimentary and volcanic rocks and asso-
ciated intrusive rocks of the Taku-Skolai terrane.
Although most boundaries of the two terranes are
concealed by snow, ice, and Wrangell Lava (Ceno-
zoic), the southern and southwestern contacts, in
places, are well exposed. These contacts are faults
that dip 50° to 60° southwest to west and separate
Alexander terrane marbles from a gabbro complex
or metamorphic rocks of the Skolai Group (Per-
mian). The gabbro complex underlies the Skolai
Group and is interpreted as a basal part of the Taku-
Skolai terrane. The complex is cut by abundant mon-
zonite plutons of late Paleozoic age. Contacts mark-
ing the northern boundary of the Alexander terrane
are concealed or partly obscured, but they also ap-
pear to be faults.

The mechanics of the faulting and the amount of
movement that occurred are conjectural. The con-
figuration of the bounding fault .(or faults), char-
acterized by a large diversity in strikes, suggests
that the Taku-Skolai terrane was thrust over the
Alexander terrane along a major regional mega-
thrust with many tens of kilometres of displace-
ment. The fact that no klippen of Taku-Skolai rocks
have been found on the Alexander terrane may be
attributable to the extreme Cenozoic uplift and at-
tendant vigorous erosion of the region and to the

 

limited, broad reconnaissance nature of field investi-
gations, both in Alaska and in Canada.

Petrography, age, and tentative correlation of the schist at

Willow Creek, southwestern Talkeetna Mountains

Detailed geologic investigations by Béla Csejtey,
Jr., and K-Ar age determinations by J. G. Smith on
the enigmatic schist at Willow Creek suggested
that the schist had a complex and still not fully
known geologic history (loc. 18).

The schist crops out in an approximately 16><
6-km block in the southwestern Talkeetna Moun-
tains. The block was intruded on the north by Up-
per Cretaceous and lower Tertiary plutons, and it
is bounded on the south by the Cenozoic Castle
Mountain fault. Rocks lith-ologically similar to the
schist at Willow Creek have not been found in near-
by regions.

Lithologically, the schist at Willow Creek is a
highly schistose, medium-grained rock with uniform
lithology throughout its exposure area. Its ubiqui-
tous constituents are quartz, muscovite, albite,
chlorite, numerous chloritized grains of garnet and
subordinate biotite, and sparse stringers of carbo-
naceous material. Small, open folds and crenula—
tions are common througoutthe schist block. The
axial planes of these crenulations form an incipient
slip cleavage at a large angle to the primary schis-
tosity. .

The present mineral assemblage of the schist is
that of the greenschist metamorphic facies. How-
ever, it is retrograde from higher metamorphism,
possibly the amphibolite facies, as evidenced by the
chloritized garnet and biotite crystals and sparse
mineral outlines consisting now of chlorite, which
are probably pseudomorphs after hornblende. The
time relation between this retrograde metamor-
phism and the incipient slip cleavage is unknown,
as is the time gap between these later events and
the primary metamorphism. '

Potassium-argon age determination on muscovites
from three separate localities yielded early Ter-
tiary ages, around 60 my Although it is not known
which metamorphic event or what thermal effect.
these dates identify, they tend to disprove, in con-
junction with regional geologic considerations, the
previously assigned Precambrian or early Paleozoic
metamorphic age for the schist.

The uniform petrography of the schist at Willow
Creek, the presence of serpentinized ultramafic
bodies, and the lack of similar rocks in adjacent re-
gions suggest that the schist block is a tectonically
emplaced fragment of a larger metamorphic terrane.

70 GEOLOGICAL SURVEY RESEARCH 1975

Ongoing petrologic research and additional K-Ar
age determinations will hopefully decipher the com-
plex geologic history of the schist at Willow Creek.

Rocks within the schist block are similar in lithol-
ogy and K-Ar ages to metamorphosed Upper Pa-
leozoic rocks, about 200 km to the east, in the
Chugach Mountains north of the Border Ranges
fault (H. C. Berg, unpub. data, 1974). These rocks
are interpreted by MacKevett and Plafker (1974)
to be part of the upper plate of a late Mesozoic and
early Tertiary subduction system.

SOUTHWESTERN ALASKA

Tectonic significance of Lower Cretaceous rocks in the Bristol
Bay area

Recent studies by J. M. Hoare, W. L. Coonrad, R. L.
Detterman, and D. L. Jones yielded interesting
new data on the age and structure of the Mesozoic
rocks north of Bristol Bay (10c. 19). Strata of Early
Cretaceous age, which are exposed in the Goodnews
A-3 quadrangle and parts of the adjoining A-2 and
B-2 quadrangles, are particularly interesting be-
cause (1) they are 2,500 to 3,500 m thick and are the
least deformed thick section of Lower Cretaceous
rocks known in southwestern Alaska; (2) they are
richly fossiliferous; (3) they include a coeval lime-
stone facies and a conglomeratic facies; (4) they
contain clear evidence of Late Jurassic tectonic
activity; and (5) they are restricted to a small area
and were preserved by tectonic activity.

These Lower Cretaceous strata unconformably
overlie Lower Jurassic volcanic rocks in an area of
about 450 km2 between the Ungalikthluk and Kulu—
kak Rivers. They were apparently preserved from
erosion in a structurally low tectonic block largely
defined by the Ungalikthluk and Kulukak faults.
The Valanginian strata were deposited as two con-
trasting lithologic facies, both of which contain co-
quinas of Euchiu ci'ossz'colis. One facies consists of
180 m of limy grit and fine conglomerate with inter-
bedded Buchz‘ar-shell limestone. The other consists of
about 1,000 to 1,500 m of conglomerate with inter-
bedded siltstones and Buchia coquinas. The unlike
clasts indicate that the two facies had different
source terranes. The two facies must have been de-
posited some distance apart, but they now crop out
in two parallel belts that are only 2 to 5 km apart.
The belts are on either side of a reverse fault that
dips southeastward. The facies have apparently
been telescoped by southeastern compression.

The highly calcareous strata of Valanginian age
contain abundant phyllite and fine-grained schist
clasts. The source of these clasts is the Lower Jur-

 

assic volcanic rocks, which are locally metamor-
phosed in the vicinity of faults. The Lower Jurassic
volcanic rocks were apparently metamorphosed by
tectonic activity in Late Jurassic time because no
rocks of Late Jurassic age are known and no meta-
morphic clasts were found in a thick marine section
of Middle Jurassic age.

The restricted occurrence of the Lower Cretaceous
rocks can probably be explained in one of two ways.
The simple explanation is that they were preserved
from erosion in a structurally low tectonic block
between reverse faults that dip steeply southeast.
A more radical explanation is that they were pre-
served beneath a large allochthonous plate of Jur-
assic volcanic rocks and are now exposed in an
erosion window.

Precambrian rocks in southwestern Alaska

The Kanektok basement complex is a narrow, dis-
continuous belt of schists and gneisses in southwest-
ern Alaska (loc. 20). It is named for the Kanektok
River, which flows westward across the complex.
The belt, about 130 km long, extends northeastward
from near Jacksmith Bay on the Bering Sea coast
along the northwestern flanks of the Ahklun and
Kilbuck Mountains. The complex was originally de-
fined by J. M. Hoare and W. L. Coonrad (1959,
1961) during the reconnaissance mapping of the
Bethe] and Goodnews 1:250,000-sca1e quadrangles.
A Precambrian age was assigned to the crystalline
rocks in the complex because they are strongly
metamorphosed, whereas nearby fossiliferous strata
of Devonian and Permian age, although severely de-
formed, are not significantly metamorphosed.

Confirmation of the occurrence of Precambrian
rocks in Alaska has recently become a matter of
considerable interest, particularly in relation to
plate tectonic modeling of Alaska. R. B. Forbes, in
a petrographic study of the specimens collected dur-
ing the original investigation, identified sedimentary
and volcanic rocks as well as some mafic and gran-
itic intrusive rocks metamorphosed in the upper
greenschist and lower almandine—amphibolite facies.
Potassium-argon dating of mineral separates from
three different specimens by D. L. Turner (Geophys-
ical Institute, Univ. of Alaska) yielded hornblende
ages of 1,072:32 my and 533i16 my and a bio-
tite age of 437:13 m.y. These initial data suggest
that the rocks. are indeed of Precambrian age and
that they were subjected to thermal overprinting
in Ordovician time or later.

The Kanektok complex is apparently the first
Alaskan terrane to yield K-Ar dates suggesting a

REGIONAL GEOLOGIC INVESTIGATIONS 71

Precambrian age. Additional work is being under-
taken to obtain more isotopic age measurements
and to delineate the age relationship within the
Kanektok complex.

SOUTHEASTERN ALASKA
Tertiary granitic rocks dominate Coast Range batholithic
complex in northern southeastern Alaska

New studies along the international boundary in
the Tracy Arm-Fords Terror Wilderness Study Area
by D. A. Brew, A. B. Ford, and D. A. Grybeck, con—
tinuing studies by Brew and Ford in the Juneau Ice-
field area, and available reconnaissance information
on intervening and adjacent areas indicated that
granodiorite and quartz monzonite of established
or inferred middle Tertiary age probably underlie
most of the Coast Range batholithic complex be-
tween the Stikine River and the Skagway area (10c.
21). Several bodies are represented, the largest of
which appears to be the 50-m.y.-old “Turner Lake”
body of the Juneau Icefield area. In general, the
bodies intrude granitic gneisses to the southwest,
but, locally, they extend across the granitic gneiss
belt almost to the schist belt that forms the south-
western boundary of the Coast Range batholithic
complex. To the northeast, the bodies intrude ther-
mally metamorphosed rocks that are largely of
Mesozoic age. At a very few places the Tertiary
granitic bodies are associated with volcanic rocks
that may be comagmatic.

Timing of metamorphism and plutonism in the Coast Moun-
tains near Ketchikan

New K-Ar determinations by J. G. Smith from
southern southeastern Alaska (loc. 22) delineated
three belts, each with a distinctive pattern of ages
that coincides with major rock units in the Coast
Range metamorphic-plutonic complex. More than 70
K-Ar determinations, including 30 biotite-hornblende
pairs, were made on metamorphic and plutonic rocks
collected across the Coast Range from Stewart,
British Columbia, to near Ketchikan, Alaska. From
east to west, the ages most probably represent (1)
intrusive ages of Eocene plutons, (2) a middle Ter-
tiary thermal-metamorphic event, and (3) partial
to complete resetting of'older ages, probably by the
middle Tertiary thermal event.

The eastern belt consists, with but one exception,
of concordant 50-m.y. biotite-hornblende ages from
unfoliated leucocratic quartz monzonite and grano-
diorite plutons (for example, Hyder Quartz Monzo-
nite, Boundary Granodiorite). The single exception
is the Texas Creek Granodiorite, a small pluton that
gives strongly discordant ages of 200 my. on hom-

 

blende and 120 my. on biotite. This pluton is intruded
by the Hyder Quartz Monzonite. The preservation of
older ages in a terrane of younger plutons and the
closely concordant 50-m.y. biotite and hornblende
ages suggest that the 50-m.y. ages are intrusive
ages and not a reflection of the regional cooling
history.

Ages in the central belt are mildly discordant:
hornblende averages about 50 my, and biotite about
44 my Rocks in this belt are sillimanite- and ky-
anite—grade schists, gneisses, and migmatites and
foliated diorite, quartz diorite, and granodiorite.
Mineral ages show no correlation with rock type or
position in the belt. Instead, biotite ages are about
the same throughout the belt, as are hornblende
ages, although there is a 6-m.y. difference between
the two groups. This pattern of apparent ages in a
high-grade metamorphic terrane suggests that the
ages were set by a middle Tertiary thermal-meta-
morphic event.

The western belt consists of apparent ages that
increase from 52 my. (hornblende) and 44 my
(biotite) in the east to 80 to 85 my. along the
western shore of Revillagigedo Island. Rocks in
this belt are metasedimentary and metavolcanic
schists and gneisses of greenschist to lower amphib-
olite facies and foliated quartz diorite and sub-
ordinate granodiorite. Biotite and hornblende ages
increase from east to west, but at different rates.
Discordance is about 8 my. in the east, increases to
20 my near the middle of the belt, and decreases
to a few million years in the west. This pattern sug-
gests that rocks yielding apparent ages of 80 to 85
my. Were reset by a heat source to the east.

PUERTO RICO

Age relations in the San Lorenzo batholith

The San Lorenzo batholith occupies an area of
approximately 500 km2 in southeastern Puerto Rico.
Recent geologic mapping in the area by C. L. Rogers
and new radiometric age determinations by R. F.
Marvin furnished a clearer picture of the nature and
sequence of intrusion of the batholith. At least three
intrusive phases are present.

The oldest rocks in the batholith range in com-
position from diorite to gabbro, have a radiometric
age of about 78.1:22 my, and occur in small
plutons clustered around the margin of the batho-
lith. The major part of the batholith, perhaps 75
percent of the surface area, is granodiorite to quartz
in composition and has an average age of about
73.5123 m.y. The youngest unit forms a number of
scattered small to moderately large plutons that

72 GEOLOGICAL SURVEY RESEARCH 1975

range in composition from quartz monzonite and
granodiorite near the center of the batholith to
quartz diorite near the margin. Age data are not yet
available, but almost certainly, this unit was in-
truded during latest Cretaceous to early Tertiary
time.

Back-arc-basin sedimentary rocks and the protrusion of bastite
serpentinite

Analysis of faunal and physical characteristics of
the Yauco Mudstone, Lago Garzas Formation, and
Sabana Grande Andesite of Mattson (1960) in the
Ponce Pefiuelas, and Yauco quadrangles of south-
western Puerto Rico suggested to R. D. Krushensky
that these units were deposited in shallow, warm
water in near-shore shelf or lagoonal environments.
Features indicative of high-energy shoals or banks
and forms indicative of lagoonal environments are
both separate and mixed. When they are mixed,
coarseness and extreme angularity of the consti-
tuent clasts suggest only very short transport be-
fore final deposition. Small-ripple bedding and flaser
bedding, both abundant in the Yauco, are also char-
acteristic of shallow deposition. Flaser bedding sug-
gests, in addition, alternation in supply of silt and
clay, perhaps indicating changes in. sediment supply
in the wet and dry seasons. Southwestward direc-
tion of transport in soft-sediment deformation,
crossbedding, and coarsening in the Yauco, as well
as northward thickening of the Lago Garzas and the
Sabana Grande, suggest that the paleoslope dipped
to the south-southwest. Polarity of the arc-trench
association suggests that these rocks were deposited
in a back-arc basin.

Alpine-type bastite sepentinite was emplaced
within and beneath these units, perhaps as protru-
sive diapirs. Although all previously known contacts
are sheared and have been considered faults, one
newly exposed contact of serpentinite with the
Yauco Mudstone appears unequivocally intrusive,
but contact metamorphic effects, even the recrystal-
lization of the calcareous cement of the Yauco, are
not apparent. Presumably, these serpentinite bodies
are derived from the uppermost mantle or from
oceanic crust undergoing subduction. Their rise may
have been triggered by a decrease in strength at-
tendant on dehydration that could accompany move-
ment into areas of higher temperature, by a de-
crease in density accompanying shearing (Lock-
wood, 1972), by tectonic movement, or by a com-
bination of these factors and perhaps others. The
bastite serpentinite of southwestern Puerto Rico
appears to correspond to the thermal diapir en-

 

visaged by Karig (1971) as intruding the back-arc
basins of the western Pacific.

Stratigraphic relations of Cretaceous rocks

Detailed field studies by R. P. Volckmann of Upper
Cretaceous rocks in the San German and Puerto
Real quadrangles indicated that revision of earlier
stratigraphic concepts is necessary. The strati-
graphic units involved include the Mayaguez Group
and the San German Formation (Mattson, 1960).
As originally described (Mattson, 1960), the Maya-
guez Group comprised seven lithofacies: the Par-
guera, Brujo, and Melones Limestones, the Yauco
Mudstone, the Sabana Grande Andesite, and the
E1 Rayo Volcanics and Maricao Basalt. The Maricao
Basalt crops out north of the area under study and
is not included in this discussion. Mattson (1960)
believed that each of these seven lithofacies inter-
fingers locally with all of the others and that the
Melones Limestone is the youngest of the group. The
entire sequence was believed to range in age from
Santonian(?) to early Maestrichtian. The San Ger-
man Formation (Mattson, 1960), thought to be
middle Maestrichtian in age and to rest uncomform-
ably on the Brujo Limestone of the Mayaguez Group,
consisted of two units: a basal series of andesite
flows and agglomerates and a thick, massive lime-
stone, the Cotui Limestone Member, near the top
Of the formation.

Recent field mapping shows that the San German
Formation consists of three units: (1) a basal series
of hornblende-rich lavas and breccias, (2) the Cotui
Limestone Member, and (3) an upper series of
pyroxene-rich tuifs, mudstones, and thin lenses of
massive limestone. The Cotui is found to be equiva-
lent to the Brujo Limestone, and, therefore, the San
German Formation is not un-conformable on the
Brujo. The Cotui has been paleontologically dated as
late Campanian or older. The upper unit of the San
German Formation bears fossils that indicate a Cam-
panian to Maestrichtian age and is lithologically
similar to sequences in the Sabana Grande Andesite
of the Mayaguez Group. Thus, it is probable that the
San German Formation does not overlie the Maya-
guez Group. In fact, the lower San German may be
older than the Mayaguez Group, whereas the middle
and upper parts of the San German are equivalent to
the Mayaguez Group.

The Melones Limestone, originally thought to be
of early Maestrichtian age (Mattson, 1960), was
considered to be at the top of the Mayaguez Group,
overlying the El Rayo Volcanics and stratigraph—
ically lower than the San German Formation. How-

REGIONAL GEOLOGIC INVESTIGATIONS 73

ever, recent mapping has shown that the Melones
consists of several lenses interbedded with the El
Rayo. N. F. Sohl dated the Melones paleontologically
as middle Maestrichtian. These data suggest that
the El Rayo, With the interbedded Melones Lime-
stone, overlies the rest of the Mayaguez Group in
the San German area.

GEOLOGIC MAPS

Much of the work of the USGS consists of map-
ping the geology of specific areas, mostly for pub—
lication as quadrangle maps at scales of 1:24,000,
1: 62,500, and 1 : 250,000. Mapping the geology of the
United. States is a mandate of the Organic Act estab-
lishing the USGS; a long-range goal is the comple-
tion of geologic maps of the country at scales that
will fulfill foreseeable needs and uses.

The systematic description and mapping of rock
units serve a major scientific objective by showing
local and regional relationships, but most maps also
serve more specific purposes. Some of the studies
are for the purpose of extending geologic knowledge
in areas of know interest; some are to gain detailed
knowledge for engineering planning or construction.
Still other mapping studies are carried on with the
primary objective of providing solutions to prob-
lems in paleontology, sedimentary petrology, or a
wide variety of other specialized topics.

LARGE-SCALE GEOLOGIC MAPS

Large-scale geologic mapping, principally at scales
of 1:24,000 and 1:62,500, constitutes about four-
fifths of the geologic mapping program of the USGS.
Such large-scale maps are available for about a
quarter of the conterminous United States. Approxi-
mately half these maps have been produced by the
USGS; most of the remaining maps have been pro-
duced by various State organizations and by educa-
tional institutions.

The ‘ USGS is carrying out large-scale geologic
mapping projects in many parts of the country, with
extensive cooperative programs underway in Con-
necticut, Kentucky, Massachusetts, and Puerto Rico.
Other areas where mapping is underway include the
Pacific Northwest, California, Delaware, Maine,
Maryland, Michigan, Nevada, New Hampshire, Ohio,
Pennsylvania, Tennessee, Virginia, Wisconsin, and
the Rocky Mountain States.

Large-scale geologic maps play a vital role in fur-
thering scientific knowledge of the Earth and also
have many applied uses. Maps of mineralized areas

 

not only help determine the scientific principles that
govern formation and distribution of ore deposits
but are also used as the basis for exploration of eco-
nomic mineral deposits and for the preparation of
reserve and resource estimates.

Many geologic maps are prepared in the search
for a better understanding of the processes and
mechanisms that affect the Earth’s crust. Uses of
these maps are growing in number and importance
in the field of planning for more logical land use
and for such large—scale engineering works as dam-
sites, highway alinements, and subway routes.
Actual construction is aided by locating vital con-
struction materials and by providing the basis for
site-preparation cost estimates. Another extremely
valuable use of geologic maps is as an aid to avoiding
hazards such as landslides, swelling clays, and areas
possibly subject to extensive damage during floods
and earthquakes.

INTERMEDIATE-SCALE GEOLOGIC MAPS

Geologic mapping at a scale of 1:250,000 makes
up an increasingly important part of the USGS geo-
logic investigations program. The 1:250,000-scale
and smaller scale geologic maps generally are com-
piled from available large-scale geologic maps and
supplemented by reconnaissance geologic mapping at
intermediate scales. Mapping at 1:250,000 has now
expanded to constitute more than one-fifth of the
geologic mapping program of the USGS. Many State
geological surveys also have 1: 250,000—scale geologic
mapping programs underway or completed. These
efforts by Federal and State surveys as a nationwide
program promise to provide geologic map coverage
of two-thirds of the United States by 1985; at pres-
ent, nearly 40 percent is covered. Figures 2 and 3
show the areas of the United States for which
1 1250,000-scale maps have been published.

The USGS is participating in mapping programs
that will provide 1:250,000—sca1e geologic maps for
all or most of Alaska, Colorado, and Nebraska within
a few years. Single-sheet 1° X2° geologic maps have
been started in parts of Arizona, Idaho, Montana,
New Mexico, North Carolina, Oregon, South Caro-
lina, Virginia, Washington, and Wyoming.

Intermediate-scale geologic maps have a variety
of uses. They help define areas where the need for
larger scale maps is most critical, and they direct
attention to broad geologic problems involving large
segments of the Earth’s crust. They have proved
ideal for geologic analysis of major tectonic and
stratigraphic problems, for analysis of mineral prov-

GEOLOGICAL SURVEY RESEARCH 1975

74

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76 GEOLOGICAL SURVEY RESEARCH 1975

inces, and for relating broad geophysical anomalies
to surface geology. A significant use for maps at
intermediate scales, although still largely a potential
use at this time, is as a basis for a systematic inven-
tory of land uses and resources throughout the
Nation.

MAPS 0F LARGE REGIONS

Several maps of individual States or of all or large
parts of the United States are currently in prepar-
ation or have recently been published. These map-s,
at scales ranging from 1:500,000 to 1: 10,000,000,
present reviews of various geologic features of the
Nation in forms that show overall characteristics
of the features in detail commensurate with the
scales. Most are intended both as wall maps for
contemplative reviewing and as working maps for
further specific studies.

Geologic map of the United States, exclusive of
Alaska and Hawaii, scale 1: 2,500,000, P. B. King and
H. M. Beikman, compilers; three sheets.

Compilation of the new geologic map of the con-
terminous United States was completed in 1972,
and the map was published late in 1974 (King
and Beikman, 1974a). The map legend, which
comprises the third sheet, shows more than 150
map units arranged horizontally according to
age and divided vertically into six general
classes of rocks, including marine stratified de-
posits, continental deposits, eugeosynclinal de-
posits, volcanic rocks, plutonic and intrusive
rocks, and metamorphic rocks. Correlation of
Precambrian rocks and of the Phanerozoic plu-
toni-c and volcanic rocks is based on radiometric
dating. An “Explanatory text to accompany the
geologic map of the United States” was pub-
lished separately (King and Beikman, 1974b).
Metallogenic map of North America, scale
1:5,000,000, P. W. Guild, compiler.
This map is a contribution to the Metallogenic
Map of the World, sponsored by the Commission
for the Geological Map of the World of the IGC
and the IUGS. The map is being prepared in
cooperation with the Geological Survey of Can-
ada; the Institute of Geology, National Auto-
nomous University of Mexico; the Geological
Survey of Greenland; and the Central American
Institute of Investigation and Industrial Tech-
nology. The map will show major known de-
posits of metal-bearing and nonmetallic miner-
als, as well as their geologic-tectonic settings.
A coproduct of the map compilation will be

 

computer storage of data on deposits to facili-
tate rapid retrieval.

Geologic map of Arkansas, scale 1:500,000, re-
vision by the Arkansas Geological Commission, N. F.
Williams, Director, and the USGS, B. R. Haley;
assisted by E. E. Glick (USGS) and W. V. Bilsh,
B. F. Clardy, C. G. Stone, M. B. Woodward, and D. L.
Zachry (Arkansas Geological Commission).

This revision of the State geologic map, begun
in 1968 as a cooperative project, has been com-
pleted and is being prepared for publication. The
map has been revised on the basis of published
and unpublished reports and reconnaissance
mapping.

Geologic map of Colorado, scale 1: 500,000, 0. L.
Tweto, compiler.

This new map, begun in 1971, will supersede the
existing map published in 1935. The map, which
is about 40 percent completed, will depict the
vast increase in knowledge of the geology of
Colorado during the last 40 yr.
Geologic map of Nevada, scale 1:500,000, J. H.
Stewart and J. E. Carlson, compilers.

Compilation of the first comprehensive geologic
map of Nevada, prepared in cooperation with
the Nevada Bureau of Mines and Geology, has
been completed, and the map is being prepared
for publication. A preliminary black and white
map has been published (Stewart and Carlson,
1974a) , and color copy is also available (Stewart
and Carlson 1974b). The compilation draws on
data from about 5001arge— and small-scale maps,
many of which have been used previously in
compilation of 1:250,000-scale county maps.
Field checking and remapping have been done
in areas where county maps are incomplete or
out of date. The new map will show nearly 100
geologic units.

Geologic map of Oregon, scale 1:500,000, G. W.
Walker, compiler.
Compilation of this map, which includes more
than 50 geologic units, has been completed, and
it is being prepared for publication. A map of
the western part of the State was published
previously (Wells and Peck, 1961), and a pre-
liminary black and white version of the eastern
part of the State was published in 1973 (Walker,
1973). The data are based partly on available
published and unpublished maps and partly on
extensive new reconnaissance and photogeologic
mapping. An insert tectonic map shows distri-
bution of fold axes, major surface faults, and

REGIONAL GEOLOGIC INVESTIGATIONS 77

the position of postulated calderas and deeply Paleotectonic maps, scales 125,000,000 and 1: 10,-
buried faults. 000,000, as follows: Analysis of the Pennsylvanian
Geologic map of Wyoming, scale’12500,000, J. D. 3375th by E- 13- McKee and others; Analysis Of
Love, compiler. the Mississippian System by L. C. Craig and others.

A new map is being compiled in cooperation Both analyses are completed and include maps

with the Geological Survey of Wyoming. This
map, which will replace the State map published
20 yr ago, is based 75 percent on new data.
Compilation is more than half completed, and
parts of the compilation have already been used
in a LANDSTAT environmental study, in the
RALI program, and in Wyoming Geological
Survey county resource reports.

showing total thickness of rocks of the two sys—
tems, thickness and lithofacies of the divisions
of the systems, and distribution of rocks under-
lying and overlying the systems. In addition,
interpretive maps show the transport direc—
tion of sediments, restored thicknesses, and
tectonic development of the country during the
two periods. Some maps show paleogeography
and some show environments of deposition at

Metamorphic facies map of Alaska, scale 112,500,-
000, D. A. Brew, Chairman, Branch'of Alaskan
Geology Compilation Committee.

This map is a contribution to the Map of the re r d f bl' t'
Metamorphic Belts of the World, sponsored by p pa e or pu 1ca ion.

the Commission for the Geological Map of the Seismotectonic map 0f the eastern United States,
World of the IGC and the IUGS, and to the scale 125,000,000, by J. B. Hadley and J. F. Devine;
joint USGS-State of Alaska Geological Survey three sheets, one text pamphlet.

selected times during the periods. The Analysis
of the Pennsylvanian System is in press, and the
Analysis of the Mississippian System is being

publication on the geology of Alaska. The map
will show metamorphic facies, facies groups,
facies series, selected isograds, and granitic
rock bodies in the style of the IUGS (Zwart
and others, 1967) suggested metamorphic facies
map explanation. Progress includes preliminary
compilation and review of regional metamorphic
facies maps at 121,000,000 scale for all of the
State and coding of background metamorphic
mineral locality information.

This black and white map was prepared by the
USGS in cooperation with the Atomic Energy
Commission (Hadley and Devine, 1974). It in-
cludes maps showing major geologic structures,
the frequency of earthquake activity from 1800
to 1972, and an interpretation of the relation-
ship of the seismicity to the geologic structures
and tectonic provinces for the area east of the
Mississippi River. The text gives a summary
of the structural and seismic history of the area.

WATER-RESOURCE INVESTIGATIONS

The USGS conducts investigations, surveys, and
research on the occurrence, quality, quantity, dis-
tribution, utilization, movement, and availability of
the Nation’s surface- and ground-water resources.
This work includes (1) investigations of floods and
droughts and their magnitude, frequency, and rela-
tion to climatic and physiographic factors; (2) evalu-
ations of available waters in river basins and ground-
water provinces, including assessment of water re-
quirements for industrial, domestic, and agricultural
purposes; (3) determinations of the chemical, physi-
cal, and biological characteristics of water resources
and the relation of water quality and suspended-
sediment load to various parts of the hydrologic
cycle; and (4) studies of the interrelation of the
water supply with climate, topography, vegetation,
soils, and urbanization. One of the most important
activities of the USGS is the systematic collection,
analysis, and interpretation of data for evaluating
the Nation’s water resources. These data are com-
puter processed for storage, retrieval, and dissemi-
nation of water information. _

The USGS is responsible for coordinating national
network and special water-data acquisition activities
and maintaining a central catalog of water informa-
tion for use by Federal agencies and other interested
parties.

Research is conducted to improve the scientific
basis of investigations in hydraulics, hydrology, in-
strumentation, and the chemical, physical, and bio-
logical characteristics of water.

Subjects currently under investigation or re-
searched recently by the USGS include the following:
(1) Properties of water—geochemistry, temperature,
and water chemistry; (2) drain-age, runoff, and wa-
tersheds—flood plains, floods, frozen ground, playas,
and storm runoff; (3) evaporation, meteorology, and
precipitation—droughts, evapotranspiration, glaci-
ers, glaciology, ice and icing, snow, and transpira-
tion; (4) flow, hydraulics, and streams—availability
of water, base flow, channel morphology, culverts,
drainage, flood-flow formulas, flood hazards, flood-
inundation maps, fluid mechanics, gaging, geo-

78

 

morphology, highway drainage, hydraulic engineer-
ing, hydrodynamics, low flow, measurement of
streamflow and time of travel under ice, mine acid
drainage, overland flow, river basins, rivers, seepage,
storm drainage, stratified flow, streamflow, stream
classification, and water problems of the coal indus—
try; (5) ground water—aquifers, artesian aquifers,
artificial recharge, availability: carbonate-rock hy-
drology, connate water, core sampling, dispersion of
contaminants, earthquake effects, electric-analog-
model studies, flow, geochemistry, geochronology,
geophysical logging, hot springs, hydraulics, hydro-
geology, hydrologic properties, interpretations, in-
vestigations, levels, mapping, nuclear-explosion ef-
fects, nuclear-waste disposal, piezometric maps, pol-
lution, pumping and pumpage rates, quality, quanti-
ty, radiocarbon dating, research, resistivity studies,
saltwater intrusion, springs, subsidence of land, test-
well drilling, thermal water, use of water, use of iso-
topes in investigations, waste disposal, and wells; (6)
soil water—soil moisture, soil-water movement, and
soil-water relationships; (7) lakes and reservoirs—
biology and ecology, evutrophication, impoundments,
lake levels, lake basins, limnology, ponds, and strati-
fication; (8) water and plants—phreatophyte con-
trol, plant-water relationships, and tree rings; (9)
erosion, sedimentation, and sediments—«reservoir
sedimentation, reservoir siltation, Siltation, sediment
control, and sediment transport; (10) quality of
water—biological and ecological aspects of water
chemistry, brine, chemical analysis, geochemistry, in-
organic constituents, kinetics, radioactivity in water,
salinity, solutes and solutions, and trace elements;
(11) estuarine problems~biological and ecological
problems, brackish water, distribution of sediments
and wastes, tidal studies, transient flow, and up-
stream movement of saltwater; (12) water use—
agricultural use, aluminum industry, copper indus-
try, evaporation control, evapotranspiraxtion control,
hydroelectric use, industrial use, municipal use,
petroleum industry, pulp and paper industry, rayon-
and acetate-fiber industry, styrene-butadiene indus-
try, surface- and ground- and wastewater use, syn-

WATER-RE SOURCE

thetic-rubber industry, and water requirements;
(13) agriculture, irrigation, and pesticides—move-
ment in streams and ground water of pesticides, wa-

ter requirements, and water spreading; (14) water 1

management—flood control, management of ground—
and surface-water resources, and use of models; (15)
water-pollution effects, water-pollution sources, and
water quality—agricultural sources of pollution, de-
tergents in water, effect of pollutants on aquatic life,
industrial wastes, movement of pesticides and other
pollutants in streams and ground water, pesticides in
water, pollutant identification, radioactive rainout,
saline-water intrusion, source of pollutants, tempera-
ture, and thermal pollution; (16) waste disposal——
radioactive-waste disposal and waste-water disposal;
(17) planning and water-resources development—de-
velopment of ground- and surface-water resources,
flood forecasting, river-basin planning, water bud-
gets, and water supply; (18) water law; (19) en-
vironments—antarctic regions, arctic regions, arid
lands, deltas, deserts, karst terrain, swamps, urban
areas, and wetlands; (20) water-resource studies——
appraisals, computer applications in water research,
data processing, evaluation, hydrologic data, infra-
red application, instrumentation for hydrologic stud-
ies and resources research, interpretations, investi-
gations, mapping of ground water, model studies,
processing, publication, remote sensing, reports, re—
search, stochastic hydrology, techniques for hydro-
logic studies and resources research, and telemetry;
(21) corrosion—well casings; and (22) water cycle.

A significant part of USGS water-resource activi-
ties is providing scientific and technical assistance to
other Federal agencies. When USGS interests are
related to the interests of other agencies, USGS as-
sistance contributes to the efficiency of their pro-
grams and encourages the maintenance of high
standards of technical accomplishment.

technology and the technologies necessary for deal-
ing with (1) the chemical, physical, and biological
properties of water and (2) the interrelation of
these water-quality properties within the environ-
ment.

During fiscal year 1975, data on streamflow were I
' ground-water data. Digital-computer techniques are

collected at about 7,480 continuous-record discharge
stations and at about 9,000 lake- and reservoir-level
sites and partial—record streamfiow stations. About
12,000 maps of flood-prone areas in all States and

Puerto Rico have been completed to date, and about ,

800 pamphlets covering areas susceptible to flooding
have been published. Studies of the quality of sur-

 

 

INVESTIGATIONS 79
face water were expanded; there were approximately
4,970 water-quality stations in the United States and
in outlying areas where surface water was analyzed
by the USGS. Parameters measured include those of
selected major cations and anions, specific conduct-
ance or dissolved solids, and pH. Other parameters,
measured as needed, include trace elements, phos—
phorous and nitrogen compounds, detergents, pesti—
cides, radioactivity, phenols, BOD, and coliform bac-
teria. Streamflow and water-temperature records
were collected at 3,865 of the water-quality stations.
Sediment data were obtained at over 1,070 locations.

Annually, about 500 USGS scientists report par—
ticipation in areal water-resource studies and re-
search on hydrologic principles, processes, and tech—
niques. Nearly 300 of the studies in progress are
classed as research projects. Of the current water-
resource studies, about 350 are related to urban hy—
drology problems.

In fiscal year 1975, 511 areal appraisal studies were
carried out. Maximum and mean areas of the studies
were 1.5 million and 74,000 kmz, respectively. Total
areal appraisal funding was about $21 million.
Ground-water studies have been made or are cur-
rently in progress for about two-thirds of the Nation.
In 1975, scheduled measurements of ground—water
levels were made in about 28,000 wells, and periodic
measurements were made in many thousands of oth-
er wells. Studies of saline-water aquifers, particular-
ly as a medium for disposal of waste products, are
becoming increasingly important, as are hydrologic
principles governing the occurrence of brackish wa-
ter in estuaries. Land subsidence due to ground-
water depletion and the possibilities for induced
ground-water recharge are under investigation in
areas where the land surface has settled significantly.

The use of computers—in research studies of hy-

, drologic systems, in expanding data-storage systems,
The USGS develops ground- and surface-water '

and in quantifying many aspects of water-resource
studies—continued to increase during fiscal year
1975. Records of about 280,000 station-yr of stream-
flow acquired at about 10,000 regular streamflow
stations are stored on magnetic tape, and data on

, about 100,000 wells and springs have been entered in

a new automated system for storage and retrieval of

used to some extent in almost all the research proj-
ects, and new techniques and programs are being
developed continually.

Final reports on USGS water-resource activities
that were part of the IHD were concluded in 1975
following the close of the IHD in 1974.

80 GEOLOGICAL SURVEY RESEARCH 1975

The principal publications devoted to basic hy-
drologic data are in the following series of USGS
water-supply papers: (1) “Surface-Water Supply of
the United States,” (2) “Quality of Surface Waters
of the United States,” and (3) “Ground-Water Levels
in the United States.” In addition to these basic-data
reports, other series of water-supply papers describe
(1) the magnitude and frequency of floods for the
entire country, (2) floods by drainage-basin areas,
and (3) noteworthy floods for each year.

Requests for data on water use in the United
States and in relatively small areas increased in 1975.
The need to develop energy sources of various kinds
in areas where industrial development has been non-
existent or minimal requires estimates of future wa-
ter requirements in these areas and evaluation of the
adequacy of the water resources to meet the demand.
Studies are underway to improve methods for ex-
panding the scope, intensity, and accuracy of water-
use investigations.

Investigations describing the occurrence of water
as a natural resource are given in the following sec-
tions for the four regions of the United States (fig.

 

4) used since 1973 by the USGS for administering
the water-resource program.

NORTHEASTERN REGION

Intense rainfall on saturated soil in the Red Cedar
River and Grand River basins resulted in severe
flooding in the Lansing, Mich., metropolitan area dur-
ing the period April 19—21, 1975. The peak flow of
the Red Cedar River in the Lansing area was the
highest since 1904, and that of the Grand River was
the highest since 1947. Property losses were esti-
mated to be $50 million.

Ideal melt conditions of the snowpack in Minne-
sota, which was reported to contain as much as 254
mm of water, reduced peak runoff to only a moderate
flood hazard. Peak discharges resulting from the
snowmelt were generally at or below 10-yr recur-
rence levels.

Model studies were begun to evaluate the effects
of urbanization and ether development on flows in
the Susquehanna River basin in Pennsylvania. Par-
ticular emphasis will be placedon evaluating effects

 

FIGURE 4.—Index map of the conteminous United States, showing areal subdivisions used in the discussion of water resources.

WATER-RESOURCE

of reservoirs and powerplant operations. Secondary
emphasis will be placed on providing flow-routing in-
formation for use in early warning of impending wa-
ter shortages.

Landfill studies in the northeastern region con-
tinued, and increased emphasis was placed on tracing
movement of organic compounds through shallow
aquifers and toward streams. Studies were begun in
Maine to assess or to index the trophic state of the
State’s lakes, which are a vast water resource.

The quality of streams in the upper part of the
White River basin in Indiana was recently assessed
in a comprehensive study. Besides water quality, the
study included dynamic hydrology, geology, and
socioeconomic factors.

An interdisciplinary study of the Conewago Lake
drainage basin in Pennsylvania was made to docu-
ment the present physical, chemical, and biological
conditions of the 8-yr-old manmade lake and to postu-
late the relations between the natural environment
of the basin and the chemical quality of streamflow
and their effect on eutrophication.

A study evaluating the results of analyses of sam-
ples of water, bed material, fish, and soil collected in
four small drainage basins in Pennsylvania was com-
pleted. Each basin represented a predominant land-
use classification—forested, general farming, resi-
dential, and orchard. Data gathered during the study
are being used to assess the occurrence of pesticide
residues in different types of land-use areas.

A three-dimensional “hybrid” computer model of
the Long Island aquifer system was used to study
the impacts of various waste-disposal regimes on the
hydrology. The model combines an analog technique
of computation with digital methods of data process-
ing and output. As sewers replace septic tanks and
cesspools in more areas of Long Island, aquifer re-
charge is progressively reduced. The model was used
to study the effect of recharge reduction on ground-
water levels and streamfiow in Nassau County and
is currently being used to study the same effect in
southwestern Suffolk County. Future studies will be
islandwide and in addition will consider the effects of
various regimes of artificial recharge and increased
pumping of ground water. These studies will be
closely coordinated with work funded by the EPA
under Section 208 of the Federal Water Pollution
Control Act, in which a comprehensive waste-dis-
posal plan for the island is to be developed.

A three-dimensional analog model of the Indi-
anapolis area was used to study the effects of in-
creased pumpage on ground-water levels and stream-

 

INVESTIGATIONS 81

flow. Increased utilization of ground water for the
Indianapolis municipal supply has been proposed as
an alternative to constructing a surface reservoir.
Sustaining this additional ground-water pumpage is
in question, as are probable effects on streamflow.

Similar studies of the effects of various regimes of
water and waste management were made in Dela-
ware, Massachusetts, Michigan, Minnesota, New J er-
sey, New York, Virginia, and Wisconsin. Digital
models of aquifer systems have been used in all of
these studies.

Work continued on a project to map the interface
between saltwater and freshwater throughout West
Virginia. Recent legislation requires that all oil and
gas wells in West Virginia be cased through the
freshwater zone. To enforce this regulation, the posi-
tion of the base of freshwater must be determined.
Data processing and map generation by computer
have been used to prepare preliminary maps of each
15-min quadrangle in the State. Field checking of
the maps Will be completed in about 11/2 yr. In addi—
tion to their immediate enforcement value, the maps
will be valuable in assessing saline-water resources
and the relation between connate brine and circulat-
ing fresh ground water in inland aquifer systems.

CONNECTICUT

Evaluation of stratified drift aquifers in south-central Connecticut

Hydrogeologic data collected from 140 test holes
by F. P. Haeni and R. L. Melvin were used to evalu-
ate the water-bearing characteristics of stratified
drift aquifers in south-central Connecticut. Areas
with significant saturated thickness and trans-
missivity have been identified in the Quinnipiac,
Eight Mile, and Farm River valleys. Seismic surveys
in the Farmington and Quinnipi-ac River valleys have
indicated areas of thick stratified drift; these will be
confirmed by subsequent test drilling.

INDIANA

Effect of landfills on water quality varies

R. A. Pettijohn reported that the results of a study
of landfills in Marion County indicated that the effect
of landfills on water quality varies from site to site.
One landfill, which is in a ground-water discharge
area, has little effect on ground-water quality beyond
the perimeter of the refuse. A second, in a till area,
evolves much gas (methane and carbon dioxide) ;
leachate is brought to the surface by the gas and dis-
charged into a stream. A third, on a flood plain, con-
taminates the deepest unconsolidated aquifer; a part

82 GEOLOGICAL SURVEY RESEARCH 1975

of the natural ground-water gradient is reversed be-
cause of heavy pumping. A fourth, also on the flood
plain, contributes a high concentration of leachate
to nearby ground-water bodies; the natural ground-
water gradient of this landfill also has been reversed
because of heavy pumping nearby.

MARYLAND

Ground-water resources of Harford County

Water in the metamorphic and igneous rocks of
Harford County is unevenly distributed, and its
availability is difficult to predict because the fracture
system is complex and variable. According to L. J.
Nutter, average well yields and specific capacities
within various lithologic units seem to fall into broad
groups that may constitute the basis for generalized
“ground-water availability units.” The units, how—
ever, have restricted use in planning because, within
each unit, well yields normally range over more than
an order of magnitude. Mapping of lineations on
aerial photographs and field analyses of topography
seem to be the most useful tools for selecting poten-
tially high-yielding well sites. Lineations observed
are normally topographic lows and straight reaches
of streams Whose orientation seems to be controlled
mainly by joints and faults.

MASSACHUSETTS

Water resources of the Nashua River basin

Results of studies by B. P. Hansen and R. A.
Brackley of the Nashua River basin showed that
large supplies of water suitable for industrial or pub-
lic supplies can be obtained from glacial deposits.
Aquifers of glacial-outwash and ice-contact deposits
lie primarily in the major stream valleys and can be
divided into three levels of transmissivity——-O to 125
mg/d, 125 to 370 mz/d, and more than 370 Ina/d.

Time-of-travel investigations on the Shawsheen River,

northeastern Massachusetts

Time-of-travel and longitudinal-dispersion studies
on the Shawsheen River were made by F. B. Gay and
Massachusetts Division of Water Pollution Control
personnel; the base data are for use in the State’s
predictive water-quality computer-simulation model.

In the upper half of the river, a dispersion coeffi-
cient of 11.1 mZ/s was computed for a 9.56-km
stretch of river having a discharge of 1.61 m3/s, a
fall of 3.14 m, and a well-defined stream channel
that meanders on a 91.4-m-wide grassy flood plain.
In the lower half of the river, a dispersion coefficient

 

of 17.6 mg/s was computed for a 9.69-km stretch of
river having a discharge of 3.14 m3/s, a fall of 12.13
m, and a gently curving pool and riffie channel. These
coefficients are similar to those that R. G. Godfrey
and B. J. Frederick (1963) determined for similar
streams in Virginia.

The time required for the peak concentration of a
contaminant to travel the entire length of the river
(41.5 km) at a medium-range index discharge of 1.50
m-"'/s was 3 d, whereas it would be in excess of 151/; d
at a low-range index discharge of 0.20 ma/s.

Graphic plots of river miles against the cumulative
travel times of peak concentrations revealed that
only one of the five impoundments along the stream
significantly affects streamflow velocity and then
only in the low range of discharges.

Preliminary results of an aquifer test in Truro

J. H. Guswa and C. J. Londquist reported that a
preliminary analysis of data from an aquifer test in
the town of Truro on Cape Cod indicates that average
hydraulic conductivity is 20 m/d for the upper 36 m
of the Wellfleet plain outwaSh deposits of Pleistocene
age. Analyses of selected samples indicate that sand-
particle size is generally medium but can range from
very fine to coarse.

During pumping of a test well, water-level changes
were measured in 10 observation wells screened at
different depths in the aquifer. Specific yield and the
ratio between the vertical hydraulic conductivity and
the lateral hydraulic conductivity of the aquifer were
estimated by comparing observed water-level
changes with changes indicated by a digital radial-
fiow model developed by E. P. Weeks, who used an
assumed hydraulic conductivity of 20 m/d and an
assumed specific storage of 1.3x 10—4 per metre. The
best fits were obtained by using a specific yield of
0.10 and a ratio of vertical hydraulicpconductivity to
lateral hydraulic conductivity of 1:1 to 1:5. These
conductivity ratios do not apply below a depth of
17 m.

Supplies of ground water readily available on Nantucket Island

on Nantucket Island, water occurs in the moraine
along the northern part and in the sheet of glacial
outwash to the south. The moraine contains much
sand and gravel, and domestic water supplies ‘can be
obtained with little difficulty at most places through
driven well points. The sand and gravel of the out-
wash yields water readily. According to E. H. Walk—
er, the municipal water supply of the town of Nan-
tucket is pumped from a field of 80 well points, which

WATER-RESOURCE INVESTIGATIONS 83

can yield 3,780 mS/d. A 30-cm-diameter well that pro-
vides part of the supply for Siasconset yielded 33 1/ s
with 2.7 m of drawdown. A few 15-cm-diameter wells
drilled for irrigation have been reported to yield as
much as 25 l/s.

Buried gravel is largest source of ground water along

Connecticut River lowlands in Massachusetts

The principal aquifer in the Connecticut River low-
lands of Massachusetts is a sheet of coarse sand and
gravel that lies upon bedrock or till and under a
blanket of silt, clay, and fine sand. Apparently, the
sand and gravel was deposited at the edge of a
shrinking glacier by many small streams of melt-
water. The overlying fine-grained materials accumu-
lated in postglacial Lake Hitchcock, which spread
northward up the lowlands in the wake of melting
ice.

According to E. H. Walker, S. W. Wandle, Jr., and
W. W. Caswell, almost all public-supply wells in the
lowlands tap the buried gravel. Yields of some wells
exceed 63 l/s, even where the aquifer is only 3 m
thick. The wells are artesian and, in some places, flow
at the surface. Recharge enters the aquifer where
the cover of fine-grained materials is thin and along
the margins of the lowlands. The water is of good
quality in most places (but may contain objection-
able amounts of iron near swamps), is hard, and has
a high sulfate content in some places.

Storage requirements for water supply in the Connecticut Valley

A regional storage analysis of the Connecticut
River lowlands basin in Massachusetts by S. W.
Wandle, Jr., W. W. Caswell, and E. H. Walker indi-
cated that demands for water less than 5.5 l s—1 km—2
can be satisfied by impounding the high flow each
year for later release during low-flow periods (sea-
sonal storage). Draft rates in excess of this amount
can be met by storing water during wet years for
later release during dry years (over-year storage).
Storage requirement estimates for ungaged sites in
the basin are- indexed to the unit median-annual-
minimum 7-d mean flow. Regional draft, storage, and
frequency curves developed in this analysis provide a
first approximation of the amount of storage re-
quired for given draft rates. Losses due to reservoir
evaporation, sedimentation, and seepage are not
included.

Water resources of southeastern Massachusetts

Reconnaissance geologic mapping and analyses of
well data by R. E. Willey and J. R. Williams showed
that the principal aquifers in the Seekonk to Ware-

 

ham area of southeastern Massachusetts are local-
ized in preglacial valleys cut in bedrock. Permeable
materials, which form aquifers in these valleys, con-
sist of deltaic, ice-contact, and outwash deposits.
Ground water in parts of the study area is subject to
saltwater contamination from seawater intrusion,
ocean-storm flooding, and highway deicing chemicals.
G. D. Tasker’s analyses indicated that the 7-d 10-yr
low flow of the streams in the area may be as much
as 0.1 mi/s.

MICHIGAN

Geology and hydrology for environmental planning in Delta

County

The geologic and hydrologic characteristics of Del-
ta County were studied by W. B. Fleck and C. J.
Doonan, and a series of maps was prepared to aid
planners and managers in evaluating land-use al-
ternatives. Using the map series, Michigan Geological
Survey personnel prepared a summary map showing
areal suitability for landfill sites. Most of the more
suitable areas are in the northwestern and south-
eastern parts of the county. Approximately half of
the State-approved landfill sites are in areas that
have been shown on maps to be favorable from geo-
logic and hydrologic standpoints.

The study indicated that the Munising Sandstone
of Cambrian age has a high potential for large with-
drawals of water. The Trenton and Black River Lime-
stones also are major sources of water; the upper
parts have been drilled extensively for domestic wa-
ter supplies. Except in the northeastern part of the
county, Pleistocene deposits are generally less than
10 m thick and are of less importance for water
supplies.

Geohydrology of Muskegon waste-water spray-irrigation site

A three-layered digital model was developed by
W. B. Fleck to simulate ground-water flow character-
istics in the vicinity of the Muskegon County waste-
water treatment site. The model predicts the effects
of future stresses on the ground—water system as the
application of waste water by spray irrigation is
increased. The 4,000-ha irrigation site at Muskegon
is underlain by 75 to 90 m of Pleistocene deposits.
The upper 20 m is a sand and gravel aquifer having
a shallow water table. The aquifer is underlain by
confining beds of silt and clay and some lenses of
sand. The water-table gradient is westward toward
Muskegon.

Underlying the Pleistocene deposits are the Michi-
gan Formation,. the Marshall Formation, and the

84 GEOLOGICAL SURVEY RESEARCH1975

Coldwater Shale, all of Mississippian age. The Mar-
shall Formation is generally permeable and has a
good water-producing potential, but some beds near
the top of the Marshall Formation have been con-
taminated by gypsum leached from the overlying
Michigan Formation.

Ground water in southeastern Michigan

An area of 14,000 km“ in southeastern Michigan
has a population of nearly 5 million. Although most
water supplies for the area are obtained from
streams and lakes, about 12 percent of the popula-
tion uses ground water. Industrial, municipal, and
rural-domestic supplies are obtained from glacial de-
posits and bedrock, according to F. R. Twenter.

Glacial deposits are as much as 150 m thick and
have varying yields. Where deposits contain large
amounts of sand and gravel, they may yield as much
as 190 l/s. Ann Arbor, Waterford Township, and
Ypsilanti Township, the largest users of ground
water, individually withdraw 90 to 260 l/s. Where
glacial deposits contain large amounts of clay, as
they do in the eastern part of the area, yields are
commonly less than 0.32 l/s.

Bedrock formations that are tapped as sources of
water are the Saginaw Formation, the Marshall For-
mation, the Goldwater Shale, the Berea Sandstone,
the Traverse Group, the Dundee Formation, the De-
troit River Group, the Sylvania Sandstone, and the
Bass Islands Dolomite. Of these, the Saginaw, Mar-
shall, Berea, and Sylvania generally yield the great-
est quantities of water—in some places as much as
201/s.

The chemical quality of ground water varies with
well depth and rock type. At shallow depths, most
water has dissolved-solids concentrations ranging
from 200 to 700 mg/l. The dissolved-solids concen-
tration increases as the well depth increases, and
many deep wells yield water that is highly mineral-
ized. In some places, shallow wells in bedrock also
yield water that is highly mineralized. Most waters
in southeastern Michigan are very hard (over 180
mg/l) and have iron concentrations ranging from 1
to 4 mg/ 1.

MINNESOTA

Digital models used to predict effects of irrigation on the
hydrologic system
S. P. Larson (1975) used two digital models to
predict water-level declines and sources of pumped
water under different hypothetical plans of irriga-
tion development of sandy soils overlying a surficial

 

outwash aquifer. The model simulations constituted
a significant part of a study of a sand-plain area near
Appleton. Effects on the hydrologic system during
20 yr of withdrawing water from the outwash aqui-
fer under (1) present (actual), (2) maximum (hypo-
thetical), and (3) 50-percent maximum (hypotheti-
cal) irrigation development were depicted on maps
and graphs. The models showed that the present an-
nual withdrawal rate of 1.74 km3 of water for irriga
tion would result in water—level declines of less than
0.9 m after 20 yr, whereas annual withdrawals of
10.4 km3 would cause aquifer dewatering and de-
creased yields in some places. After a new state of
equilibrium was established in response to with-
drawals, most of the withdrawal would consist of
diverted base flow from the Pomme de Terre River.

Ground water near Alexandria

M. S. McBride reported that digital models of two
surface-outwash aquifers near Carlos and Parkers
Prairie were completed.

Well yields greater than 0.06 mi/s can be obtained
in about one-third of the Carlos outwash area (73
kmz). Under maximum development, average water
levels in the irrigated area should decline 0.6 to 2.4 m.
The water would be derived almost entirely from the
Long Prairie Rive-r.

Well yields greater than 0.06 m3/ s can be obtained
from most of the Parkers Prairie outwash area (490
km3). Under maximum development, average water
levels in the irrigated area should decline 0.3 to 1
m. About half of the water would be derived from the
stream and about half from salvaged evapotranspira-
tion.

Outwash areas near Clotho, Urbank, Alexandria,
and Rose City have less potential. Irrigation supplies
may be available in places, but the saturated section
of the surface aquifer is generally too thin for large-
capacity wells.

Effects of dewatering a roadcut in Hennepin County

M. S. McBride completed a digital model designed
to predict (1) the rate of pumping required to de-
water an outwash sand and gravel deposit for high-
way construction at a railroad underpass and (2) the
effects of that pumping.

The pumping rate needed to dewater the cut was
predicted to be 0.057 m3/s. At this rate, water levels
in the cut area would decline to within 0.3 m of the
design level within 3 to 6 weeks.

Effects of pumping on nearby Twin, Crystal, and
Ryan Lakes were of particular concern. Under
steady-state conditions, Twin and Crystal Lakes

WATER-RESOURCE

would be the sources of 75 percent or more of the
water pumped. If none of the water is returned to the
lakes, declines in average lake levels can be expected
to be within the following ranges: Twin Lakes, 0.06
to 0.3 m; Crystal Lake, 0.02 to 0.06 m; and Ryan
Lake, 0.2 to 0.6 m. .

Three analytical models also were used to predict
the required pumping rate. This modeling was done
to check the results of the digital model and to in-
vestigate the value of such models for making quick
estimates of pumping rates. The results obtained
(0.051, 0.062, and 0.059 mg/s) were within 10 percent
of the values given by the digital model.

Deep aquifers in Brooten-Belgrade area, west-central Minnesota

According to R. J. Wolf, test drilling in the Broo- ‘

ten-Belgrade and Lake Emily area indicated deeply
buried, confined, coarse sand and gravel aquifers as
thick as 15 m. In places (north of Belgrade, north-
west of Brooten, east of Villard, and southwest of
Lake Emily), the aquifers are thick and permeable
enough to yield large quantities of water to wells.
The aquifers are not extensive and sheetlike, how-
ever. but are rather narrow, elongate, and winding.
Only by drilling closely spaced test holes can they be
mapped in detail. Although large quantities of water
may eventually be pumped from the aquifers, draw-
down may be excessive locally, owing to nearby im-
permeable boundaries (clay till). Preliminary test
results in the buried outwash aquifer northwest of
Brooten indicate a transmissivity of 136 mZ/d and a
hydraulic conductivity of 30 m/d.

Deposits of Cretaceous age were penetrated in
many of the test holes, but sandstone was notably
absent. Coarse water-bearing sand, gravel, and cob-
ble beds were found at the bottoms of the Cretaceous
rocks in some places but were generally not thick
enough for large withdrawals of water.

Ground water in Park Rapids area

J. O. Helgesen studied water availability from a
1,943-km2 surficial outwash aquifer in the Park
Rapids area. Preliminary test augering has indicated
that (1) the aquifer consists typically of fine sand
to fine gravel, (2) depth to the water table ranges
from about 0.9 min much of the southern part of the
area to over 9 m in the northern part, and (3) satur-
ated thickness ranges generally from 3 to 9 m in the
south and 6 to 18 m in the north.

Water resources of the St. Louis River watershed
Virtually all potable water in the St. Louis River

 

watershed is from ground-water sources. Sand and

INVESTIGATIONS 85

gravel in the drift is the most favorable source, al-
though Precambrian bedrock (primarily the Biwabik
Iron-formation in the northern part of the water-
shed) is tapped where drift water is inadequate. Test
augering in the northern part of the watershed indi-
cated that the glacial-lake sand, typically very fine to
fine and less than 3 m thick, is a poor source of water.
According to G. F. Lindholm, D. W. Ericson, W. L.
Broussard, and Marc Hult, outwash sand and gravel
east of Eveleth is as thick as 15 m and, at least local-
ly, is a good source of water. Large amounts of sur—
face water are used in the iron-mining and wood-
processing industries.

Water-supply sources in the Lake Superior watershed

Lake Superior provides a large quantity of water
of good quality to nearby municipalities and indus-
tries. Elsewhere in the watershed, aquifers provide
small to moderate amounts of water for domestic and
farm uses. Thin clayey till in much of the area and
thick lake clay in the central Nemadji River basin
are generally inadequate for water supplies. Thick
outwash and sandy-till deposits and the Hinckley
Sandstone provide adequate yields for most purposes
in the Nemadji basin. The Duluth Complex, volcanic
flows, and associated rocks in the remainder of the
watershed are the principal aquifers and yield from
0.06 to 1.26 Us to domestic and farm wells generally
less than 5.1 m deep, according to P. G. Olcott, P. E.
Felsheim, W. L. Broussard, and D. W. Ericson.

Reconnaissance of sand-plain aquifers

Surficial sand deposits cover more than 31,000 km"
in Minnesota. Studies of the availability of water
have been made in seven sand-plain areas. These
studies cover 12 percent (4,000 kmz) of the deposits
in the State. H. W. Anderson, Jr., evaluated data
from the remaining 88 percent of the deposits.

Data on water use for irrigation, irrigation per-
mits, saturated thickness, area of surficial sand de-
posits, observation wells, water in storage, and range
in well yields, collected from many sources, are being
processed for manipulation by the System-2000 data—
base management system.

Low-flow variations in southeastern Minnesota

K. L. Lindskov found that in southeastern Minne-
sota the unit discharge for a drought of 7 consecu-
tive days recurring on an average of once every 10
yr decreases as the basin size increases. Figure 5
plots the unit discharges against the drainage areas
for 26 tributaries draining into the Mississippi River

’below St. Paul and above Lock and Dam 8. The rela-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

DRAINAGE AREA. IN SQUARE MILES
e 10 20 50 100 200 500 1000 2000
IIIII I IIIIIIII I IIIIIIII I
‘3 5-0' I I I I II I I I I II I I T
E . T g~040 3
,__
mu; 7* I“:
:5 F ' a...
a“; 2.0 \ '- Pozoog
3 \ ' - go
3‘ \ cm
5‘ . \\ o 2‘:
:‘g 10 . \. 7010 7‘5.”
2: ' r— 5n
—0 . ‘,— {:2
NW __ (0
g: “eons?38
(L05 ‘ em
I _ Of:
a I4 7 ,.
E 03 I I [III I l IIIL I I L’0-03
15 20 so 100 200 500 1000 2000 7000

DRAINAGE AREA. IN SQUARE KILOMETRES

FIGURE 5.—Unit discharges of 7-d droughts of 10-yr duration
in Mississippi tributaries below St. Paul, Minn., in relation
to drainage areas.

tionship on figure 5 shows that the unit discharge of
a 7-d drought of 10-yr severity varies as the —0.15
power of the drainage area; that is, data indicate
that the discharge is proportional to the drainage
area to the 0.85 power.

The area studied is part of the Wisconsin Driftless
section of the Central Lowland province and is cov—
ered by loess overlying Paleozoic limestone, sand-
stone, and dolomite.

NEW JERSEY

‘Saline ground water

J. E. Luzier and R. L. Walker, J r., investigated the
vertical head distribution, salinity, and temperature
variation of water in a well tapping the Potomac-
Raritan-Magothy aquifer system of the Coastal
Plain. An abandoned 1,127-m oil test hole was jet
perforated and tested at five zones from depths of
640 to 1,036 m. The altitude of the water level at
each of the zones, adjusted for density, temperature,
and pressure, ranged from — 5 m at 640 m to 1,036 m.
Chloride concentration increased from 11,000 mg/l
at 640 m to 27,000 mg/l at 1,036 m. Temperature pro-
files before testing were concave downward, this con-
dition suggesting upward gradients and, therefore,
upward leakage. After the last pumping test at 640
m, repeated temperature logging showed a rapid
thermal recovery in the well bore (7°C Within 3 d).
After 28 d, the temperature was within 0.1°C of the
original thermal gradient.

Computer model of outwash valley-fill aquifer

A computer model was developed to simulate a
glacial-outwash aquifer in Morris and Essex Coun-
ties. The outwash was deposited in an interconnected
series of five valleys during the last glaciation. Cali-
bration of the model was based upon comparison of
computed water-level declines with declines measured

 

GEOLOGICAL SURVEY RESEARCH 1975

in 12 observation wells during one or more periods,
ranging from 3 to 19 yr, since 1953. Harold Meisler
used the calibrated model to determine the quantity
of water available from the valley-fill aquifer. On the
basis of the criterion that water levels would stabilize
at least 9 m above the base of the aquifer, the model
indicated that pumpage of approximately 1.8 m3/s,
about 40 percent more than the 1972-73 rate, could
be obtained on a continuous basis. All of the increase
would have to come from two of the valleys, as the
other three are probably already fully developed.

Digital simulation of the Wenonah-Mount Laurel aquifer

A geohydrologic study by Bronius Nemickas of
the confined Wenonah-Mount Laurel aquifer in the
Coastal Plain of New Jersey involved the calibration
of a digital model. The model indicated that two-
thirds of the head decline in the Wenonah-Mount
Laurel aquifer during the simulation period (1959—
70) is related to withdrawals from the underlying
Englishtown aquifer. Although the aquifers are
separated by a confining unit ranging from 6 to 70 m
in thickness, the head differential induces leakage
from the Wenonah-Mount Laurel aquifer to the Eng-
lishtown aquifer.

NEW YORK

Aquifers defined in Dale Valley, western New York

Intensive study of water in the glacial drift of
Dale Valley, a glacially scoured trough in western
New York, revealed two aquifers, according to A. D.
Randall. The deeper aquifer, 3 to 7 m of sand and
gravel buried beneath 30 m or more of fine-grained
lake deposits, is hydraulically continuous for about 5
km along the valley axis. The shallower aquifer, 2 to
3 m of gravelly alluvium generally less than 4.5 m
below land surface, is in hydraulic contact with small
streams in the valley. Chloride concentrations in the
deeper aquifer are generally betwen 5 and 25 mg/l.
Chloride concentrations as high as 1,100 mg/l in an
area of industrial development probably were due to
migration of water from the bedrock. A digital model
is being fitted to hydraulic data for the deeper
aquifer.

Water table in Long Island, March 1974

According to water-table and net-change maps pre-
pared by E. J. Koszalka, ground-water levels have
risen a maximum of 3 m in the central part of Long
Island since March 1970. The rise is attributed to
higher than normal precipitation during 1972—73.
Water levels in a sewered and highly urbanized area

WATER-RESOURCE INVESTIGATIONS 87

of Nassau County have declined a maximum of 1.2 m
since 1970. This decline, notwithstanding the higher
than normal 1972-73 precipitation, resulted from the
combined effects of ground-water withdrawals and
sewering.

PENNSYLVANIA

Occurrence of saline water in northwestern Crawford County

Much of northwestern Crawford County is under-
lain by rocks of Devonian age that contain saline
water at depths less than 30 m below the land sur-
face, but few quantitative salinity data are available.
G. R. Schiner and J. T. Gallaher tested a 45-m—deep
hole and determined the following:

1. Water at a depth of 5.5 m had a chloride content
of 30 mg/l and a specific conductance of 750
,rth.

2. To a depth of 15 m, chloride content and specific
conductance remained about the same.

3. At 20.7 m, however, chloride content rose to 425
mg/l, and specific conductance rose to 2,400
,uth.

4. At 30.5 m, chloride content rose to 600 mg/l, and
specific conductance rose to 4,000 [£th-

5. At 45 m, chloride content rose to 2,575 mg/l, and
specific conductance rose to 7,000 pth.

Basement flooding by ground water

Results of a recently completed study by D. J.
Growitz indicated that basement flooding in the
Kingston area has been caused by ground water.
During years of average precipitation, approximate-
ly 25 percent of the 155-ka study area can experi-
ence either seasonal or constant flooding problems.
The area is underlain by a complex ground-water
reservoir consisting of 30.5 m of unconsolidated
deposits overlying conglomerate, sandstone, shale,
and anthracite coal beds; these coal beds have been
partly or wholly removed by mining, depending on
their accessibility.

In addition to the low relief of the Kingston area
and its proximity to the Susquehanna River, both of
which foster a high water table, two other factors
also contribute significantly toward creating flooding
problems: (1) Recovery of water levels after cessa-
tion of deep mining and dewatering pumping and (2)
land subsidence.

Possible means (other than pumping) of lowering
the high water table in problem areas include (1)
gravity-drain wells, (2) gravity-overflow wells, (3)
sealing the channel of a local creek, and (4) a sub-
surface drainage ditch.

 

VIRGINIA

Chemical quality of ground water in the Coastal Plain

Results of S. M. Rogers’ ground-water—quality in-
vestigation in the Coastal Plain of Virginia showed
that the chemical composition of water from each
major aquifer is distinctly characteristic of that
aquifer. Water type changes from bicarbonate to
chloride in two of the major aquifers. West of the
transition zone in the Tertiary sediments, the water
type is calcium-magnesium bicarbonate; in the Cre-
taceous aquifer, it is sodium bicarbonate. East of the
transition zone, all ground water is predominately a
chloride type, having at least 250 mg/l of chloride.
The transition zone seems to be narrow and extends
in a generally north-south direction. Further study
will be necessary to delineate the nature and extent
of the freshwater-saltwater interface.

Water-level changes in southeastern Virginia

Ground-water use at a large industrial plant in
Franklin was drastically curtailed between July 21
and August 23, 1974; pumpage was reduced from
approximately 1.5 m"/s to 0.13 m3/s.

Near the center of the well field, the water level
recovered about 14 m; it recovered about 9 m at the
northern and southern extremities of the field.
Water-level recoveries of 1.2 m and 0.5 m were noted
in wells 12 km southeast and 19.3 km northwest of
the pumping center.

0. J. Cosner used this information to evaluate the
accuracy of a digital model of the Lower Cretaceous
aquifer.

WEST VIRGINIA

Acid water only local in the Coal River basin

Periodic sampling of stream water at 14 sites in
the Coal River basin for nearly 2 yr provided key
data on the variation of stream-water quality with
time and discharge. An additional 100 sites were
sampled at low flow and again at high flow. According
to J. L. Chisholm, chemical analyses of all samples
indicated acidity only locally in headwaters. Biologic
data support this finding; most phytoplankton found
in the streams are those common to alkaline water.

In Boone County, which constitutes most of the
basin, coal was mined from 1846 to 1861 and from
1909 to the present; therefore, the stream water
could be expected to be acid, but it is not. The reason
for the lack of widespread acidity is not fully under-
stood, but it is probably a combination of natural

88

limestone neutralization and man’s activities in water
treatment and mine safety.

Ground-water hydrology of Berkeley County

According to W. A. Hobba, Jr., more than 350
ground-water levels were determined, water samples
were collected, and 13 streamflow measurements
were made in Berkeley County during a 2-week peri-
od of declining water levels in July and August 1973.
In January 1974, some sites were remeasured during
a period of rising ground-water levels, and water
samples were collected and analyzed for nitrate and
bacteria. A similar study was made in adjacent Jeff-
erson County during a 2-week period in August and
September 1974. Water levels in the carbonate rocks
of these counties fluctuate considerably, as does the
chemical quality of the ground water, so that the
water-table and water-quality maps prepared from
the collected data are representative only for the
time of measurement. Specific conductance ranged
from 10 to 1,400 pmho, carbonate hardness ranged
from 3 to 700 mg/l, nitrate concentration ranged
from 0 to 143 mg/l, and chloride concentration
ranged from 1 to 255 mg/l.

SOUTHEASTERN REGION

Investigations of the demand for water, disposal
of wastes, and changes in land use related to water
resources continued to be emphasized in the south-
eastern region. Data collection and analyses of data
by modeling techniques are being intensified to pro-
vide the information necessary for the maximum
utilization of water resources to meet immediate and
long—term needs.

In Florida, several studies are underway to in-
crease recharge to stressed aquifers by using induced
infiltration, water spreading, and connector wells be-

tween shallow and deep aquifers as means of meet- .

ing increased water demand. Florida is also studying
the surface and subsurface disposal of solid and
liquid wastes involving landfills, ponds, water spread-
ing, and disposal wells. In Tennessee, the delineation
of fracture traces in limestone areas from aerial
photographs has enabled investigators to select areas
where yields to wells may be greater than normally
expected. A deterministic flow model was developed
for the Chowan River Estuary in North Carolina. A
flow and water-quality model of the lower Santee
River in South Carolina is being developed in antici-

pation of a major rediversion of flow from the Cooper '

River.

 

l

GEOLOGICAL SURVEY RESEARCH 1975

ALABAMA

Water problems related to coal mining

A. L. Knight, in an investigation to document wa-
ter problems associated with coal mining in Alabama,
canvassed all sources of information in USGS files
and those of other agencies such as the US. Bureau
of Mines, EPA, the Mining Enforcement and Safety
Administration, the Geological Survey of Alabama,
and the Alabama Water Improvement Commission.
Information compiled thus far indicates that de-
watering has seriously affected the availability of
ground water for municipal and domestic supplies
and, in some areas, that land subsidence has occur-
red. Also, drainage basins have been altered quite
extensively, and the flow characteristics of streams
have changed.

A research of litigation associated with coal min-
ing has provided information that not only defined
the various problems but also proved to be an ex-
cellent means of documenting their histories. For
example, cases involving spoil banks and “foul wa-
ter” associated with coal mining were recorded as
early as 1892.

Chemical analyses of water collected from some
streams draining coal-mine areas indicate that the
chemical composition of water in the stream has been
altered. Water from strip pits, spoil banks, and coal—
washing operations contains highly mineralized acid
water; pH values for water in streams near exten-
sively mined areas commonly range from 2.1 to 5.

A study of 1:130,000-scale high-altitude color in-
frared photographs covering most of seven counties
in which coal is mined shows that there is extensive
strip mining in more than 2,330 km”.

Water-quality network—contaminated municipal supply

In 1972 a network of five wells and five springs
was established as part of a cooperative program
with the Geological Survey of Alabama to determine
the baseline of chemical character, including minor
elements of ground water, in the State. Some of these
wells and springs were used as sources of municipal
water supply.

On March 12, 1974, a water sample was collected
from a city well at Irondale in Jefferson County. Ac-
cording to W. J. Powell, the minor-element analysis
of the water sample indicated a chromium content of
55 mg ”I. On July 25, 1974, when the well was resam-
pled, the chromium content had increased to 140
mg *1. The results of these analyses were brought to
the attention of the Alabama Department of Public
Health, and a resampling of the water from this well

WATER—RESOURCE INVESTIGATIONS 89

by that agency and EPA verified a high chromium
content. The Alabama Department of Public Health
discontinued use of the well as a source of municipal
supply until an investigation could be made to deter-
mine the source of the contaminant.

Fluorescein dye used to solve a highway problem

As apart of an environmentally oriented coopera-
tive project with the Alabama Highway Department,
J. C. Scott used fluorescein dye to help solve a high-
way problem. A slide in fill beneath Interstate High-
way 59 in Etowah County resulted in failure of a
section of pavement that cost more than $1 million
to repair. A study showed that the slide was caused
primarily by water moving into the base of the rela-
tively impermeable fill. Water pressure and the lubri-
cating properties of the water eventually caused the
fill to move and the pavement to fail. Fluorescein dye
was introduced into a small “swallow hole” in a ditch
about 300 m northeast of and about 45 m above the
base of the fill. A large amount of dye appeared at the
base of the fill after about 48 h. On the basis of these
findings and the geologic and hydrologic conditions
in the area, recommendations for diverting the water
away from the slide area were submitted to the high-
way department.

FLORIDA

Low well yields and low base flows of streams in parts of
Gadsden County

The Floridan aquifer, the principal source of pota-
ble ground water in Florida, is low in permeability in
northern and central Gadsden County; generally, the
aquifer is capable of yielding water in usable quanti-
ties to domestic wells but not to large-capacity mu-
nicipal and irrigation wells. According to C. A. Pas-
cale, except for water from wells deeper than 200 m,
ground water is of high enough quality to be accept-
able for most uses; the dissolved-solids content in—
creases substantially at greater depths. Ground-
‘water levels in the county range from 30 to 70 m
below land surface, and in some areas there are large
differences in water levels in nearby wells, this fact
suggesting that there are multiple subaquifers with-
in the Floridan aquifer.

Base flows of streams in northern. and central
Gadsden County are relatively low in comparison
with those of most streams in northwestern Florida.
-Dissolved-solids concentrations range from 30 to 70
mg/l, and color ranges from 20 to 90 units.

 

Evaluation of changing land-use practices in the Myakka River

basin

Tatum Sawgrass is a large surface-depression area
of the upper Myakka River basin in Sarasota and
Manatee Counties. The main channel of the Myakka
River includes the southern part of Tatum Sawgrass.
Under previous natural conditions, Tatum Sawgrass
provided a significant amount of floodwater storage
for the Myakka River and thereby attenuated flood
peaks and flood heights in downstream reaches. Re-
cent construction of a complex system of manmade
dikes across the mouth of Tatum Sawgrass for agri—
cultural purposes severely restricted use of this
natural surface depression as a flood-storage area. As
a result, according to J. F. Turner, J r., flood-peak dis-
charges and flood heights were increased in down-
stream reaches of the Myakka River.

Effects of strip mining on shallow aquifer systems in phosphate
district

A 4,000-km2 area incorporating parts of Hillsbor-
ough and Polk Counties is being strip mined for
phosphate ore. Pumpage from the Floridan aquifer
for municipal, agricultural, and industrial use has
caused long-term withdrawals from storage and
water-level declines of as much as 30 m.

The deposits that overlie the Floridan aquifer in
this area are more than 45 m thick and contain as
many as three shallow aquifers. C. B. Hutchinson
concluded from preliminary results of aquifer tests
and water-quality analyses that the shallow aquifers
may be of limited use as a water supply. In some
areas, transmissivities of the aquifers are low, and
radium concentrations are above acceptable limits for
human consumption.

Studies of the coastal springs in west-central Florida

Flows of the short, spring-fed Chassahowitzka,
Homosassa, and Crystal Rivers are strongly affected
by tides, and saltwater may migrate upstream to the
areas of discharging springs. However, measure-
ments of migration of the salt wedge in the Weeki
Wachee River indicated to W. C. Sinclair and C. L.
Goetz that the high velocity of flow and the narrow-
ness of the channel restrict saltwater encroachment
to the lower 2 km of river channel during normal
tides.

In a companion study, J. D. Hunn reported that re-
sults of analyses of water samples indicated that off-
shore and shoreline sinks along the gulf coast in
Citrus and Hernando Counties do not discharge
freshwater except during periods of extremely heavy
rainfall.

90 GEOLOGICAL SURVEY RESEARCH 1975

Aquifer recharge evaluated in the Green Swamp area

An area having good potential for downward leak-
age was delineated by H. F. Grubb in the eastern half
of the Green Swamp area of central Florida. The
presence of a very fine to coarse-grained sand aquifer
was noted from analyses of geophysical logs and
nearly 1,700 m of continuous unconsolidated core ob-
tained from drilling through post-Miocene and Mio-
cene sediments to the top of the underlying Floridan
aquifer during the summer of 1974. Generally, the
sand aquifer was absent, and most of the unconsoli-
dated sediments were clay over the western part of
the area, and thus the potential for downward leak-
age to the Floridan aquifer was limited to a few iso-
lated areas where sand was present. Natural down-
ward leakage is limited owing to the high potentio-
metric surface over most of the Green Swamp area.
Practical benefits to be gained from this downward
leakage potential are dependent upon application of a
stress to the Floridan aquifer that would lower the
potentiometric surface.

Potential for recharge in Volusia County

After a.test drilling program directed by J. O.
Kimrey that confirmed a good hydraulic connection
between the water table and the Floridan aquifer in
central Volusia County, a digital modeling study of
the area was begun by P. W. Bush. Bush used the
USGS’s digital model (Pinder-Trescott model) for
aquifer evaluation to complete a steady-state cali-
bration for a 1500-ka area of Volusia County; the
model will reproduce the natural, unstressed poten-
tiometric surface of the Floridan aquifer. Trans-
missivities and confining-layer permeabilities dic-
tated by the model in the area of a future well field
are on the order of 1,250 mZ/d and 3><10—3 m/d,
respectively.

High nutrient concentration largely confined to the conservation

areas canal system

B. F. McPherson and H. C. Mattraw, Jr., found
that the nutrients in organic nitrogen and phosphor-
us (B. G. Waller, 1975) are largely removed from
canal water as it moves from a canal into the Ever—
glades marsh. Within several hundred metres of the
canals, nutrient concentrations approach the back-
ground level of those found in the interior marshes of
conservation areas. However, most of the nutrient-
rich water pumped into the conservation areas stays
in canals, where uptake is less than in the shallow
marshes.

 

Physical characteristics of a shallow aquifer defined by test holes

and wells

The thickness, relative permeability, and water-
table surface of the shallow aquifer in Palm Beach
County were investigated by H. G. Rodis, L. F. Land,
and J. J. Schneider. The aquifer is thickest (about
140 m) in the southeastern part of the county and
thinnest (about 45 m) in the western part of the
county. Data also show that the aquifer is most per—
meable in the southeastern part and becomes less
permeable as it thins because of the increased con-
tent of finer sand, silt, and marl. These finer ma-
terials also occur at depth and make the lower third
much less permeable than the top two-thirds. The
water-table surface is highest in the conservation
and wildlife areas near the center of the county. In
eastern areas of the county, the water table conforms
generally to the topography, but, in the southwestern
part, most water-table fluctuations are controlled by
canal pumpage.

Potentiometric levels of Floridan aquifer in Seminole County

C. H. Tibbals (1975) reported that ground-water
use is greatest in southwestern Seminole County, an
area of rapid urbanization, and in the central and
northwestern parts of the county, where large
amounts of water are used to irrigate vegetable
crops. From 1955 to 1974, potentiometric levels of
the Floridan aquifer have declined about 1.5 m in
southwestern Seminole County and about 0.6 m in
the agricultural areas. The chloride concentration has
remained virtually unchanged in southwestern Semi-
nole County. Slight declines in the potentiometric
level in the agricultural areas generally result in in'-
creased chloride concentration because these are
areas where the‘ interface between saltwater and
freshwater occurs at a relatively shallow depth.

Water resources of Manatee County

The western part of Manatee County has rapidly
changed-from an agricultural and retirement area to
an urban industrial area; in so doing, it has created
water-resource problems for the area. To evaluate
the regional effects of development, a hydrologic data
base for surface and ground water was established.

A preliminary analysis of an aquifer test within a
proposed phosphate—mining area in eastern Manatee
County was made by D. P. Brown and A. F. ,Robert-
son. The lower Ocala and upper Avon Park zones (229
to 381 m below land surface) of the Floridan aquifer
were pumped for 5 d at a rate of 142 US. Maximum
estimated values of the hydraulic parameters are:
transmissivity, 6,210 mZ/d; storage coefficient,

WATER-RESOURCE INVESTIGATIONS 91

1X10—3; and leakance, 6.7 X10—4. Aquifer test data
definitely indicate anisotropy, but additional analyses
will be necessary to determine the axes and values of
the hydraulic parameters that would result from this
concept.

Connector well completed in DeSoto County

W. E. Wilson III and C. B. Hutchinson reported
that a connector well was drilled at a 9,700—ha citrus
grove in northeastern DeSoto County. The well con-
nects the surficial sand aquifer with the deep, highly
transmissive Florida limestone aquifer. Because of
natural head differences, water moves by gravity
flow from the upper aquifer into the lower aquifer.

The connector well has two 25vcm-diameter sand-
packed screens (one in the upper unit and the other
in the lower unit of the sand aquifer), about 120 m of
15-cm casing through confining beds and a secondary
limestone aquifer, and about 76 m of open hole in the
Floridan aquifer.

The expected recharge rate of the connector well
is about 10.7 l/s under steady-state conditions. The
well captures water normally lost by runofl".

Treatment of brackish ground water best outlook for continuing

supply for the Venice-Englewood area

According to Horace Sutclifi'e, Jr., limited quanti—
ties of ground water suitable for public or domestic
supplies are available in some parts of the Venice-
Englewood area. However, treatment of brackish
ground water will be necesary to provide a continuing
supply for the area’s rapidly expanding population.
Two reverse-osmosis plants having capacities of as
much as 0.09 m3/s are either operating or under con-
struction. One area between Englewood and Venice,
yet to be investigated, might yield an additional 0.13
to 0.18 ms/s of treatable water to the district.

Hydrology of the sand and gravel aquifer in central and southern

Escambia County

A sand and gravel aquifer is the only freshwater
aquifer in the Pensacola area. Although its thickness
locally exceeds 300 m in Escambia and Santa Rosa
Counties, most of the clean sand layers are no more
than 140 m below land surface in the Pensacola area,
according to Henry Trapp, Jr. (1974). Ground water
moves southward from an area of higher head in
northern Escambia County, but virtually none of it
reaches Pensacola. A reversal in gradient represented
by the combination of (1) the large compound cone
of depression produced by industrial pumping at
Cantomnenit and (2) the natural depressions associ-
ated with stream valleys form a barrier to further

 

southward movement. Virtually all of the ground
water pumped from wells south of the reversal in
gradient comes from local recharge.

The unadjusted carbon-14 age of a sample of fresh-
water from a well in the sand and gravel aquifer was
found to be 14,050 yr. According to L. J. Schroder II
(oral commun., 1974), the most probable corrected
age is 8,200 to 9,600 yr. The age range reflects the
uncertainty in the values for the soil, air, and lime-
stone factors required for correction.

The 98-m-deep well is located at Fort Pickens on
an island in Pensacola Bay. Other wells on the island
have yielded saline water from the same depth. The
age of the water suggests that the well taps an iso-
lated lens of fossil freshwater that entered the aqui-
fer when the sea level was lower.

Saltwater intrusion endangers some coastal municipal wells in

Palm Beach County

The extent of saltwater intrusion near municipal
coastal wells in Palm Beach County was defined in an
investigation by H. G. Rodis, L. F. Land, J. J.
Schneider, and W. B. Scott. All well-field areas were
found to have been intruded to some extent. There is
no immediate threat to well fields at Riviera Beach,
West Palm Beach, and Lake Worth, where the dis-
tance to the saltwater wedge is about 1 km. Lantana,
Boynton Beach, Delray Beach, and Boca Raton also
appear to be in no immediate danger, although the
wedge is about 0.5 to 1 km from their wells. How-
ever, at Juno Beach and Tequesta, the wedge is less
than 200 m from wells.

Ground-water resources of DeSoto and Hardee Counties

Results of a study of the hydrogeologic framework
of the middle Peace River basin by W. E. Wilson III
indicated that ground water in the area is obtained
from the surficial aquifer and the Floridan aquifer.
The surficial aquifer consists principally of fine sand; _
the estimated average transmissivity is 120 mZ/d.
Wells yield 1 Us or more for domestic, lawn-irriga-
tion, and stock-watering supplies.

The Floridan aquifer consists of two units, both
primarily limestone and dolostone. The average
thickness of the upper unit (Hawthorn Formation
and the limestone unit of the Tampa Limestone) is
about 55 m. Near Arcadia, transmissivity is probably
more than 280 mZ/d. Wells yield from 1 Us to more
than 6 Us and are used mostly for domestic supplies.
The average thickness of the lower unit (Suwanee
Limestone, Ocala Group, Avon Park Limestone) is
more than 275 m. The few wells that are open to the
lower units yield more than 631/3.

92 GEOLOGICAL SURVEY RESEARCH 1975

A confining bed of clay and marl separates the
surficial aquifer and the upper unit of the Floridan
aquifer. In much of the area, the sand and clay unit
of the Tampa Limestone is a confining bed between
the upper and lower units of the Floridan aquifer.

Artificial-recharge study concluded

The surficial sand aquifer overlying the limestone
Floridan aquifer in the Hillsborough-Pasco-Pinellas
tricounty area will be a key factor in the manage-
ment of the area’s water resources. According to
W. C. Sinclair, experiments with several recharge
techniques indicate that the most successful would be
a network of subsurface drain tiles that provide flow
of water by gravity to wells open to the Floridan
aquifer. Such a system would divert more water to
the Floridan aquifer while maintaining the water
table at a level low enough to facilitate infiltration.
Tests of an experimental drain field indicate that
long-term flow of about 375 m3 (1*1 ha-1 can be ex-
pected under conditions in the study area. In the area
affected by drainage, the water table is maintained
about 1 m lower than it is in undrained control areas.
Specific yield of the surficial sand is about 0.24; thus,
a hectare of land underlain by drain tile may be in-
filtrated by 2,400 In3 more water than an undrained
hectare.

Water availability in an expanding urban area

According to H. J. McCoy (1974; B. F. McPherson
and H. J. McCoy, 1974) , the safe yield of the coastal
aquifer in Collier County was reached during the
197 3—7 4 dry season. Additional water supplies for the
1974—7 5 dry period were obtained by pumping from
a borrow pit. This additional water should suffice for
the next 2 yr until the large well field, 24 km inland,
is completed and hooked up to the distribution
system.

Landfill study in Hillsborough County

Monitoring of the water quality at a landfill near
Eureka Springs in eastern Hillsborough County indi-
cates movement of leachate through shallow aquifers
toward residences bordering the eastern side of the
site. According to Mario Fernandez, Jr., no notice-
able changes have occurred in the chemical quality
of water from the deep limestone aquifer at the land-
fill site and at nearby residences. Monitoring of a
landfill near Rocky Creek in the northwestern part
of the county indicates no lateral or vertical move-
ment of contaminants from that site.

 

Testing water-management schemes by an analog model

E. H. Cordes reported that two concepts for man-
aging the Biscayne aquifer ground-water system
were tested on the USGS’s electric-analog model at
Reston, Va. One model study proposed the addition
of a second control structure on the Smoke Cre‘ek
Canal, about 19 km inland from the coast. This sec-
ondary control would operate in response to up-
stream and downstream water levels and, in addition,
would simulate flow criteria.

A second modeling concept, called “Forward Pump-
ing,” was programed to test the utility of creating
ground-water storage by pumping from the aquifer
in anticipation of periods of abundant rainfall that
would recharge the system.

Protection of water resources by management

Broward County’s largest supplier of fresh ground
water—Fort Lauderdale’s Prospect well field—in-
creased withdrawals during the critically dry period
of 1973—74- without experiencing an inland advance
of the nearby saltwater front, according to H. J.
McCoy and C. B. Sherwood, Jr. This task was accom-
plished by using an almost completed feeder canal to
furnish enough replenishment water to the aquifer
to maintain freshwater heads at levels high enough
to retard saltwater movement inland and by'locating
additional supply wells as far inland as possible from
the saltwater front.

GEORGIA

Surface geophysical methods aid ground-water study

Surface geophysical methods were used for the
first time in a hydrologic investigation of the Paleo-
zoic strata of Georgia by C. W. Cressler and H. E.
Blanchard, Jr. Resistivity and gravity surveys have
been used to delineate buried hydrologic units, to
determine their thickness, and to detect unexposed
geologic structures commonly associated with high
permeability.

Gravity data for Cartersville in Bartow County in-
dicate that a string of industrial wells having unusu-
ally high yields—as much as 220 l/s—i-s located along
a buried reverse fault. The fault, which uplifted
quartzite of the Chilhowee Group into contact with
the Shady Dolomite, probably has a displacement of
nearly 100 m. Weathering in the fault zone ranges
from 30 to more than 60 m deep. Deep weathering of
the Shady Dolomite has produced a highly permeable
zone that yields large volumes of water to wells.

A gravity survey conducted 6 km north of Car-
tersville indicates that a large industrial park, previ-

WATER-RESOURCE INVESTIGATIONS 93

ously thought to lie on shale and sandstone of the
Rome Formation, is underlain by dolomite of the
Conasauga Formation. Gravity data show that, over
a broad area, a flat thrust fault brought shale and
sandstone of the older Rome Formation westward
into a position over the dolomite ‘of the Conasauga.
Erosion of 'the thrust sheet has exposed the dolomite
at the industrial park and resulted in a window
through the fault 0.4 km to the north. The dolomite
seems to be nearly 100 m thick, and its potential for
large well yields is good.

Test well reveals water-quality anomaly

A study of well cuttings from a USGS test well in
the Valdosta area shows that the principal artesian
aquifer, a limestone and a dolomitic limestone of
Tertiary age. can be divided into two distinct water-
bearing zones. R. E. Krause (USGS) and T. M. Kra-
mer (Georgia Department of Natural Resources)
found that the upper zone contains a calcium-bicar-
bonate-type water with a dissolved-solids concentra-
tion of less than 250 mg/l, whereas the lower zone
contains a calcium-magnesium-sulfate-type water
with a dissolved-solids concentration greater than
2,800 mg/l. A 15- to 30-m-thick layer of dense, less
permeable limestone separates the two zones. Terti-
ary tectonism has fractured this confining bed, and
differences in hydraulic head permit migration of
brackish water into the freshwater zone, principally
in areas where heavy pumpage causes greater head
differentials.

Cuttings from nearby oil test wells and prelimi-
nary examinations of cores from the USGS test well
indicate the presence of evaporite deposits in the
lower zone. These deposits include calcium sulfate
minerals, principally gypsum, and they probably are
the source of the high dissolved-solids sulfate-type
water. Intervals below gypsiferous zones within the
lower water-bearing zone yield water high in stronti-
um concentration, probably due to celestite.

KENTUCKY

Wells tapping limestone in north-central Kentucky

In the Elizabethtown area of north-central Ken-
tucky, T. W. Lambert found that the average well is
28 m deep and contains 16 m of water. The depth of
wells ranges from 9 to 102 m. The deepest wells are
in areas of surficial sand and clay deposits that were
derived from the weathering of sandstone and lime-
stone of Mississippian age. Most wells tap the St.
Louis Limestone of Mississippian age and yield

 

water having a conductance of 390 p.th at 25°C.
Wells that tap the basal St. Louis Limestone yield
water that has conductance greater than 1,000 ,1th
at 25°C and contains sulfate in amounts greater than
250 mg/l.

Beaver Creek strip-mined area restudied

The hydrologic environment of two small sub-
basins in southern Kentucky was studied during the
period 1955—59 (J. J. Musser, 1963; C. R. Collier, Jr.,
and others, 1964; C. R. Collier, Jr., R. J. Pickering,
and J. J. Musser, 1970). Parts of one of the sub-
basins, Cane Branch, had been strip mined intermit—
tently from 1955 to 1959. There was no mining in the
other subbasin, Helton Branch. The project was re-
activated for the 1974 water year. Many of the
parameters, such as streamflow characteristics and
transported chemical and sediment loads, that had
been measured in the original study were remeas-
ured. According to J. A. McCabe, preliminary results
showed that differences still exist between the two
subbasins but to a lesser degree than in the earlier
study, this fact indicating that there has been some
natural restoration of the strip-mined subbasin.

Water quality in the Kentucky River basin, eastern Kentucky

The upper part of the Kentucky River drains a
large part of the very actively mined eastern Ken-
tucky coalfield. Results of a study by R. W. Davis
showed that the predominant type of water in
streams in the coal-mining area is not acid; however,
acid drainage from mines is present. The water is
generally alkaline (pH greater than 7), and about
half of its dissolved-solids content is sulfate. The
sulfate in the water is probably a product of the
oxidation of iron sulfide minerals associated with coal
beds, and the alkalinity that more than neutralizes
most acid mine drainage is thought to come from
calcareous material within the Pennsylvanian rocks
in the area.

NORTH CAROLINA

Flow model of the Chowan River Estuary

A deterministic flow model based on the continuity
equation has been developed to provide estimates of
daily flow past selected points on the Chowan River
of northeastern North Carolina. Perhaps the single
most important feature of the model, designed by
C. C. Daniel III and programmed by F. E. Arteaga, is
its ability to calculate changes in storage for the riv-
er and- the lower portions of four major tributaries.

94 GEOLOGICAL SURVEY RESEARCH 1975

The Chowan River is an estuarine body of water
extending from the confluence of the Blackwater and
Nottoway Rivers near the North Carolina-Virginia
line to the mouth of the Albemarle Sound near Eden-
ton, N.C. Two other important tributaries are the
Meherrin and Wiccacon Rivers, both of which enter
from the west. The estuary is about 80 km long and
has an open water surface of approximately 120 kmz.
Determination of the change in storage that corres-
ponds to a change in stage is complicated by the pres-
ence of extensive swamps that border much of the
river and its tributaries. These swamps have a total
surface area nearly equivalent to that of the open
water surface, their surface elevations are generally
less than 1.5 m above mean sea level,-and they are
subject to frequent flooding. Lunar-tide variation in
the river is only about 0.3 m, but wind tides are much
more significant and cause as much as 1.2 m of varia-
tion in the water surface at irregular time intervals.

In order to determine the area of swamp subject to
flooding and thus make an estimate of the volume of
water that can be stored, maps have been drawn by
using changes in vegetation as the criteria for topo-
graphic changes. Cypress and tupelo gum trees cover
low areas subject to frequent flooding and tidal inun-
dation, whereas pine trees grow on the higher, drier
elevations within the swamp. Maps showing areas of
differing vegetation were drawn on photomosaics at
a scale of 1162,500; delineation of vegetation types
was facilitated by the use of LANDSAT (formerly
ERTS) photographs taken in the red and near-infra-
red spectral ranges. Data from these maps, together
with bathymetric data for the river channel, were
combined to formulate the stage and storage rela-
tionships that are used in the model.

The model takes as input continuous hydrologic
and meteorological data from numerous stations and
converts these data into measurements of inflow,
outflow, and changes in storage for selected segments
of the estuary. The model then solves the continuity
equation to provide estimates of flow through the
estuary.

Ground-water resources of Wilson County

The most significant sources of ground water for
Wilson County are (1) the sand beds of the Cre-
taceous aquifer system in the Coastal Plain section
of the county, where maximum sustained yields of
individual wells are estimated to be about 16 to 19
VS, and (2) the bedrock aquifer system of the Pied-
mont section, where the maximum sustained yield is»
estimated to be about 7.9 US in stream valleys having
perennial streams as sources of recharge.

 

A general decline of the water level associated with
the Cretaceous System is centered around the Sara-
toga-Stantonsburg area, where the decline rate has
averaged nearly 0.45 m/ yr between 1942 and 1974.
M. D. Winner, Jr., estimated that there is about 15
to 18 m of drawdown available before water levels
will decline to the top of the uppermost sand beds of
the system and dewatering could occur around a
pumping well.

Distance-drawdown curves for a water-table aquifer

T. M. Robison used a digital computer to generate
distance—drawdown curves for an idealized Coastal
Plain water-table aquifer. The radial form of Darcy’s
law was used to compute the head differences across
concentric cylindriCal rings at increasing distances
from a hypothetical pumping well. The inputs to the
system were captured evapotranspiration and inter-
cepted base flow. These inputs varied with drawdown
and were computed for the top area of each cylin-
drical ring. The answers for each ring were deter-
mined by iteration.

PUERTO RICO

Alluvial aquifer and stream potential in Maunabo Valley

In the Rio Maunabo valley in southeastern Puerto
Rico, water from present wells will continue to meet
municipal and agricultural needs if the wells are not
overpumped. However, if the valley is to undergo
considerable industrial development, water needs will
have to be supplemented by surface-water control
structures in the upper reaches of the Rio Maunabo'
and by moderate-capacity wells in the upper part of
the alluvial valley, according to D. G. Adolphson,
M. A. Seijo, and T. M. Robison. Storage and control
structures would aid in storing water from peak run-
off periods for distribution when it is needed and in
controlling floods. _

In order to retain the maximum potential for
ground-water resources in the upper part of the al—
luvial valley, additional wells could be located along
the river. A digital model of the alluvial aquifer and
data from test holes and existing wells indicate that
the safe yield to the proposed wells would be about 13
to 32 US. Pumping rates in this range would insure
that there would be no further encroachment of salt-
water into the aquifer.

SOUTH CAROLINA

Flow and water-quality models of the lower Santee River

S. J. Playton collected data to calibrate J. P. Ben-
nett’s many-branched estuarine flow model. In addi-

WATER-RESOURCE INVESTIGATIONS 95

tion, water-quality data were collected to attempt
calibration of auxiliary transport models for sub-
stances such as sediment (for scour and degradation
computations), BOD, and DO. These models will de-
pict existing conditions and will predict discharge
and water quality in the lower Santee River, in terms
of temporal and spatial distribution, after a weekly
average of 360 m3/s have been rediverted from the
Cooper River into a channel that now routinely car-
ries 14 m3/s. Water-quality data collected to date
indicate that, with minor exceptions, water in the
lower Santee River is of excellent quality.

Ground-water resources of southernmost South Carolina

A study of the ground-water resources of Beau-
fort, Colleton, Hampton, and Jasper Counties (“low
country”) was conducted by L. R. Hayes. Prelimi-
nary data from more than 300 wells and test holes
indicate that most of the ground water in the study
area comes from a limestone artesian aquifer com-
posed of several Tertiary formations ranging in age
from middle Eocene to early Miocene and from a
deep artesian aquifer composed of sand of Late Cre-
taceous age. The limestone aquifer underlies Florida,
southeastern Georgia, and adjacent parts of Alabama
and South Carolina and is one of the most productive
aquifer systems in the United States. In the north-
ern and northwestern parts of the study area, the
deep artesian sand aquifer will yield large quantities
of soft good-quality water. However, in places, water
from this aquifer has a high temperature and con-
tains excessive amounts of fluoride.

High-fluoride-content ground water along the Grand Strand

According to A. L. Zack, there may be a relation-
ship between the ionic fluoride (as much as 5 mg/l)
occurring in ground water along the Grand Strand of
Horry and Georgetown Counties and the occurrence
of thin, limy, rock layers interbedded within the
water-producing zone. Thin sections of the limestone
indicate the presence of the mineral collophane, a
massive apatite (Ca5(P04)3F). If aquifers with such
rock layers are bypassed during well construction,
high-fluoride—content ground water can be avoided.

TENNESSEE

Linear features provide clue to ground-water supplies

Linear features proved to be hydrologically signifi-
cant in the search for ground-water supplies in the
Manchester area, according to D. R. Rima. The Man-
chester area is situated on the eastern Highland Rim
of central Tennessee and is underlain by relatively

 

flat-lying carbonate and siliceous rocks of Early
Mississippian age. The uppermost 10 to 20 m of these
rocks are deeply weathered and form a thick zone of
residuum.

Linear features that were apparent on aerial pho-
tographs were drawn on topographic maps. After
field examination, sites were selected for test drill-
ing. Eleven of 14 test wells drilled on linear features
in the area had yields ranging from 12.6 to 25.2 US.
Specific yields of the 11 wells ranged from 2 to 4 l
S" ms1 of drawdown. These values are 4 to 10 times
greater than the median values recorded for about
200 wells that were drilled in the area between 1963
and 1974.

Gains and losses in streamflow related to geologic structure

in karst area

D. R. Rima reported that, in the karst area of
Murfreesboro, a relationship has been established
between geologic structure and gaining and losing
reaches of streams. Gaining reaches usually occur
downstream from the axes of synclines and upstream
from the axe-s of anticlines. Conversely, losing
reaches usually occur upstream from the axes of
synclines and downstream from the axes of anti-
clines. In the Murfreesboro area, most of the gain or
loss in streamflow occurs where streams cross the
outcrOp area of the bottom of the Ridley Limestone,
which appears to be the most vulnerable to solution
by circulating ground water.

Highland Rim-Central Basin aquifer

The Manchester aquifer occurs in the Highland
Rim portion of the upper Duck River basin. This
areally extensive artesian aquifer is the result of the
weathering of cherty limestones of Mississippian
age. It is composed of a chert rubble layer 6 m thick
or solution openings in the bedrock. It is bounded on
the top by 18 m of clay-sized chert and at the bottom
by the Chattanooga Shale. Some wells in the aquifer
yield 25 l/s, with specific capacities of 3 l s—1 m—1 of
drawdown.

Relatively pure, dense Ordovician limestone in the
Central Basin weathers and leaves a clay soil about
1 m thick. Solution openings along bedding planes
and joints have deve10ped, and secondary porosity
has thus been created. The limestone is limited, how-
ever, in its ability to develop an areally extensive
aquifer because of the discontinuous nature of solu-
tion openings and because of a 1.2-m-thick layer of
bentonite 9 to 30 m below the land surface.

The bentonite is a barrier to the downward move-
ment of water and the upward movement of natural

96 GEOLOGICAL SURVEY RESEARCH 1975

gas. Significant solution openings do not develop be-
low it. According to C. R. Burchett (C. R. Burchett
and E. F. Hollyday, 1974), only one of 15 test wells
drilled in the Central Basin yielded more than 6.3
US. The average yield was 0.8 l/s, and six of the
holes were dry. All of the water-producing zones in
the 15 test wells were at depths of less than 30 m
below land surface, and most were between 6 and
15 m below land surface.

CENTRAL REGION

Hydrologic activities in the central region during
the past year continued, with strong emphasis on
studies related to energy development, the environ-
ment, and other water problems of national import-
ance as well as collection and timely publication of
regional water-resource data.

Water-resource investigation programs related to
coal and oil-shale mining and processing continued
and made substantial progress during the year. De-
sign and implementation of a network to define en-
vironmental baseline conditions were modified to pro-
vide for the special interests of other agencies that
have management development or regulatory re-
sponsibilities in the field of energy development. Of
special significance to coal development was the initi-
ation of the plan of study for quantitative investiga-
tion of the Madison Limestone system underlying
parts of Montana, North Dakota, South Dakota, and
Wyoming. Several reports describing the impact on
the hydrologic system of surface mining and recla-
mation in Colorado, Montana, Wyoming, and Utah
were completed. Another major effort was the prepa-
ration of environmental impact statements for coal
areas in Colorado, Montana, and Wyoming and a
potash area in New Mexico.

Investigations of the Edwards Limestone aquifer
in the vicinity of San Antonio, Tex., including deep
test-well drilling and lithologic and geophysical
studies, were begun. The investigations are expected
to provide data leading to the development of meth-
ods for accurate measurements of hydrogeologic
parameters that are needed for optimal development
of the aquifer.

In the Houston, Tex., area, investigations of the
increasingly serious land-surface subsidence result-
ing from industrial and municipal ground-water
pumpage continued. Digital models for hydrologic
studies were developed and used extensively. For ex-
ample, in Colorado, the digital model of the aquifer
system in the San Luis Valley was used to evaluate

 

the operation of the present waterasalvage project to
reduce evapotranspiration from nonbeneficial vegeta—
tion. The digital model of the stream-aquifer system
in the Arkansas River valley of eastern Colorado was
used to evaluate the impact of diverting canal water
to establish and maintain a permanent pool in the
John Martin Reservoir. A digital model was de-
veloped and used to determine the impact of oil-shale
development on the hydrology of the Piceance basin.
Snowmelt models are being developed to determine
the snowmelt streamflows from snow-packed areas
on Pikes Peak. A digital model of the Platte River
basin in Nebraska was prepared to determine the
effects of irrigation on the stream-aquifer system.

Surfacewater activities again were an important
part of the regional program. Many gaging stations
were installed in Colorado, Montana, Utah, and Wy-
oming to monitor the quantity‘and quality of stream
discharge in the coal and'oil-shale areas of those
States. District offices throughout the ,region made
substantial progress in mapping flood-prone areas,
and type-15 flood-inundation studies of specific cities
were made in several States. Flood-frequency studies
were completed in Iowa, Kansas, Missouri, Oklahoma,
and South Dakota; studies are in progress in Mon—
tana, Nebraska, North Dakota, Texas, and Wyoming.
Urban hydrology studies underway in several metro-
politan areas will define changes in runoff, water
quality, and flood peaks of streams.

Studies of the effects of waste disposal and con-
tamination on water quality of streams and aquifers
are being made throughout the central region.
Waste-assimilation studies in Arkansas have pro—
vided water-quality data for many Arkansas streams.
Maps have been prepared showing location and quali-
ty of water in lakes in the Front Range urban corri-
dor extending from Fort Collins to Colorado Springs,
Colo. USGS scientists, in cooperation with Canadian
scientists, are studying the quality of water and the
biology of Lake Koocanusa and the Kootenai River,
in northwestern Montana and northern Idaho, to de-
termine nutrient levels and chemical quality in a
stream and reservoir common to the United States
and Canada. In the Platte River valley of central
Nebraska, studies of nitrates in ground water are
underway to determine the level and sources of con-
tamination resulting from application of commercial
fertilizers to agricultural lands and other possible
point sources of contamination such as sewage la-
goons and feedlots.

Hydrologic research in the central region included
many activities related to energy development, such

WATER—RESOURCE INVESTIGATIONS 97

as hydrochemistry of water from surface coal mines
in Campbell County, Wyo., hydrologic impacts of
surface mining on ground-water aquifers and the
quality of water, and studies of changes in the or-
ganic quality of water with energy-related develop-
ment. Other investigations are related to the chemi-
cal quality of water; they include a study of the
salinity control in the Colorado River, development
of modeling techniques for the prediction of solute
transport in ground water, and development and cali-
bration of a sediment transport model.

Research on the hydrology of geothermal systems
is being conducted by field investigations and by the
design and testing of downhole probes. Instruments
have been designed and are now being tested under
the extreme pressure and heat of geothermal wells.
An instrument truck that carries 4,875 m of four-con-
ductor cable for handling these probes was placed
in operation during the year. Field studies of geo-
thermal areas are underway in Colorado and New
Mexico and are being planned to start early in fiscal
year 1976 in Montana and Utah. Grant arrangements
are in effect with two State agencies in Colorado for
examining kno.wn geothermal resource areas and for
a general Statewide reconnaissance.

ARKANSAS

Recharge to Cache River alluvial aquifer

M. E. Broom reported that, in 1973, recharge to
the alluvial aquifer in the heavily pumped rice-
growing area between the Cache River and Crowleys
Ridge in eastern Arkansas was about 0.185 ‘km‘.
The principal area of recharge, underlain by relic
dunes and dissected by perennial streams, is bounded
by the White‘River and the Ozark Plateau escarp-
ment on the west and by the Cache River on the east.

Pumpage from the aquifer in 1973 was about 0.493
kmg. A comparison of the recharge with the pumpage
indicates that about 60 percent of the pumpage is in
excess of annual recharge. Pumpage in excess of re-
charge is reflected by the water table, which declines
locally about 0.3 m/yr.

Waste-assimilation studies incorporate low-flow frequency data

M. S. Hines reported that the comparison of flow-
duration data and low-flow frequency data for 107
regular gaging stations in Arkansas reveals that, for
all practical purposes, the 99-percent duration value
is equal in magnitude to the 7-d 10-yr low flow. The
7-d 10-yr low-flow data that have been used for
stream waste-assimilation studies indicate that the

 

7-d 10—yr low flow probably will be exceeded 99 per-
cent of the time.

COLORADO

Drainage problem near Pueblo

Seepage from surface reservoirs and recharge
from irrigation maintain the water table at or near
land surface in an alluvial aquifer near Lake Min-
nequa in south-central Colorado, according to D. L.
Bingham and P. J. Emmons. The aquifer ranges in
thickness from about 0 to 7 m and is composed pri-
marily of silt and fine sand. Because of the high
water table, the area is marshy and the soil is water-
logged. Possible solutions to the waterlogging prob-
lem include construction of a cutoff trench or a drain-
tile system to improve’drainage and lower the water
table.

Selenium in ground water from the San Jose Formation

During ground-water resource studies of the
Southern Ute Indian Reservation, E. R. Hampton
found that selenium in amounts exceeding USPHS
drinking-water standards (10 ,g/l) occurs commonly
in water from the San Jose Formation of Eocene age.
Forty-one samples from the San Jose were analyzed
for selenium concentrations. Four samples contained
selenium concentrations of 700, 450, 240, and 110
,g/l; 26 other samples contained smaller selenium
concentrations that exceeded the USPHS limit for
selenium in drinking water. Most of the water was
obtained from domestic or stock wells that tap frac-
tured varicolored shale-s interbedded with massive,
poorly permeable sandstone.

Water from the underlying Animas Formation of
Cretaceous and Paleocene age contained selenium
concentrations of 45 ,g/l in 4 of 33 analyzed water
samples from wells that tap the Animas.

Water-level declines projected for western Yuma County

W. E. Hofstra (W. E. Hofstra and T. J. Major,
1974) used a digital model of the ground-water sys-
tem in a 2,000—km2 area in western Yuma County to
predict water-level declines as of the year 2000. Re-
sults of the study indicate that the maximum decline
of the water table will be centered near the town of
Yuma, where the saturated thickness (about 50 to
100 m) is greatest. A projected 15- to 26-m‘decline
will occur in an area with from 30 to 76 m of water
saturation in the Ogallala aquifer. "

Quality of ground water in Jefferson County

The quality of the water in a mountainous area of
Jefferson County is generally good, according to

98 GEOLOGICAL SURVEY RESEARCH 1975

W. E. Hofstra and D. C. Hall. The average dissolved-
solids concentration in surface water is about 110
mg/l. The dissolved-solids concentrations in ground
water are about 230 mg/l in water from the frac-
tured Precambrian aquifer and 180 mg/l in water
from the alluvial aquifer. Bacterial contamination is
more frequent in water from the alluvial aquifer than
in water from the Precambrian aquifer; coliform
bacteria contamination was found in 35 percent of
the samples from the alluvial aquifer and in 14 per-
cent of the samples from the Precambrian aquifer.
Fecal coliform contamination was found in 4 percent
of the samples from the alluvial aquifer and 2 per-
cent of the samples from the Precambrian aquifer.
Chemical degradation of well water by leach-field
leachate did not decrease significantly (95-percen-t
confidence level) until distances from wells to leach
fields were greater than 65 m.

Investigations in a coal-mining area

A geologic investigation and a surface-water re-
connaissance of a coal-mining area were made by
W. E. Hofstra and E. C. Linden. The study, which in-
cluded determination of the dissolved-solids concen-
trations of streams and springs, was made during
August 1974 in the coal-producing Yampa Valley and
Danforth Hills area. Dissolved-solids concentrations
in streams originating in the Williams Fork, 110s
and Mancos Formations commonly ranged from 550
to 700 mg/l. The trace-metal content of streams was
greatest during spring peak flows, and the dissolved-
solids concentration was greatest during the fall and
winter base-flow period. Bicarbonate was the pre-
dominant anion during peak flow, and sulfate was the
predominant anion during low flow. Magnesium con-
tent increased much more than calcium content dur-
ing the base-flow period.

Water-quality variations noted in Park County

Ground-water Quality is an important part of a
water-resource study of Park and Teller Counties.
According to J. M. Klein and K. E. Goddard, the
Idaho Springs Formation of Precambrian age in
northeastern Park County contains ground water
that has more than 200 mg/l of dissolved solids,
whereas the Pikes Peak Granite of younger Precam-
brian age contains ground water that has less than
100 mg/l of dissolved solids.

Salt Works Ranch Spring, which originates in the
Maroon Formation of Pennsylvanian and Permian
age in southwestern Park County, yields water that
has a dissolved-solids concentration of 28,200 mg/l,

 

a chloride concentration of 15,000 mg/l, and a sodium
concentration of 9,400 mg/l. Salt Works Ranch is in
an area of numerous sinkholes that result from local
dissolution and caving of evaporite beds.

Appraisal of water resources of southwestern El Paso County

R. K. Livingston, J. M. Klein, and D. L. Bingham
recently completed a water-resource study of south-
western El Paso County, where the annual water
supply consists of precipitation, surface-water inflow,
and imported water. A large part of the supply (71
percent) is estimated to be consumed by evapotrans-
piration. Mean annual precipitation ranges from 25
to 64 cm and is a function of altitude; fluctuations in
annual and monthly precipitation are extreme. The
chemical quality of surface water is generally good
except for local high-fluoride concentrations that ex-
ceed USPHS recommended standards for drinking
water. The addition of sewage effluent to lower Foun-
tain Creek deteriorates the water quality.

Ground water occurs in the Widefield aquifer, in
the alluvium in Fountain and Jimmy Camp Valleys,
and in several bedrock aquifers. A mathematical
model was prepared for the Dawson aquifer to simu-
late the effects of future withdrawals on the poten-
tiometric surface and on hydraulically connected
systems. Gain-and-loss investigations indicated that
Fountain Creek is the primary source of recharge for
the Widefield aquifer. The Widefield aquifer is the
principal source of water for domestic use in south-
western El Paso County. The chemical quality of
ground water generally is good.

Artificial-recharge experiments in Fountain Valley

Artificial-recharge experiments were conducted in
five pits excavated in the unsaturated zone above the
alluvial aquifer in Fountain Valley, according to O. J.
Taylor. The artificial-recharge rates ranged from
0.03 to 1.37 m/d and varied with stage in the pits.
The five pits, which have a total surface area of
4,650 mg, are capable of artificially recharging at
least 450,000 m3/ yr to the alluvial aquifer. Artificial-
recharge operations can contribute to better water
management in Fountain Valley by reducing short-
ages in water supply and improving water quality.

Electric-analog analysis of proposed changes in irrigation
methods in the San Luis Valley
0. J. Taylor used an electric-analog model of the
San Luis Valley to simulate the effects of proposed
changes in irrigation practices. The reduction of
surface- and ground-water irrigation in an area
southwest of Alamosa will cause a decrease in stor-

WATER-RESOURCE INVESTIGATIONS 99

age in the unconfined aquifer and an increase in stor-
age in the confined aquifer. Additional effects of the
changes will be an increase in the flow of the Rio
Grande and Conej os Rivers and a decrease in the flow
of the Alamosa River. Conversion to sprinkler irriga-
tion throughout the valley will increase streamflow
and storage in both aquifers. However, the predicted
rise in the water table will result in a large increase
in evapotranspiration.

Hydrologic evaluation of mine sites

Possible sites for an oil-shale mine in the Piceance
Creek basin were studied by J. B. Weeks and G. H.
Leavesley. The proposed mine will consist of a verti-
cal shaft sunk through water-saturated sediments to
the high-grade oil-shale deposits in the base of the
Parachute Creek Member of the Green River Forma-
tion. Four sites, selected on the basis of their geo-
logic and mineral resources, are being evaluated to
determine which site will minimize the impact of the
mine on the water resources of the Piceance Creek
basin.

A digital model of the ground-water system is be-
ing used to estimate mine-shaft-dewatering rates for
each site. Preliminary results indicate that construc-
tion of the mine shaft at a site on Ryan Gulch, a
tributary of Piceance Creek, Will produce the small-
est amount of ground-water discharge and the low-
est concentration of dissolved solids. Ground-water
discharge during construction of the mine shaft may
be as much as 0.57 m3/s, and the concentration of
dissolved solids may be 5,000 to 10,000 mg/l.

Hydrology of oil-shale lands

The hydrology of the Piceance and Yellow Creeks
drainage basin, an area of about 2,330 km2 in north-
western Colorado, was investigated by J. B. Weeks,
G. H. Leavesley, F. A. Welder, and G. J. Saulnier, Jr.
(1974), in cooperation with the Colorado Department
of Natural Resources. The annual volume of runoff
from the basin is estimated to be 19.2 mm. About 80
percent of the annual runoff is supplied by ground-
water discharge.

Runoff from the basin is affected by irrigation di-
versions and by consumptive use by crops, native
vegetation, and evaporation. Streamflow depletions
resulting from irrigation are estimated to be 5.9
hma/yr. If there were no irrigation, the mean runoff
from the basin would be 25.2 hm3/ yr. The period of
lowest flow normally occurs during spring and sum-
mer when irrigation diversions are greatest. How-
ever, peak flows from snowmelt and thunderstorms

 

occur during this period. A regional analysis, made
by using the index-flood method, estimated flood fre-
quencies in the absence of irrigation diversions. The
estimated mean annual flood rates are 22.7 m3/s for
Piceance Creek and 11.0 m3/s for Yellow Creek. The
peak flow observed during the 5 yr of record on
Piceance Creek was 11.5 m3/s, or about one-half the
estimated mean annual flood rate. Yellow Creek is
only slightly affected by irrigation diversions, and
the peak flow for the single year of record was 13.3
m3/s.

Irrigation return flows and ground-Water discharge
affect the quality of surface water in the Piceance
basin. The concentration of dissolved solids ranges
from less than 500 mg/l in the upper reaches to more
than 5,000 mg/l in the lower reaches of Piceance
Creek and from about 700 to 3,000 mg/l in Yellow
Creek. Water quality deteriorates in the downstream
direction owing to ground-water discharge from the
Green River and Uinta Formations.

The ground-water system in the basin consists of
two principal aquifers separated by the Mahogany
zone in the Green River Formation. Recharge to
the aquifers occurs mainly from snowmelt along
the basin margins above an altitude of 2,130 m.
Ground water flows from the margins toward the
north-central part of the basin, where it is dis-
charged in Piceance and Yellow Creek valleys as
evapotranspiration and streamflow. Recharge and
discharge from the aquifer system are estimated to
average 32.3 hm" annually. About 80 percent of the
recharge is discharged in Piceance Creek drainage.
Estimates of the volume of water in storage in the
aquifers range from 3,100 to 31,000 hm3.

Sodium minerals in the aquifer below the Ma-
hogany zone are actively being dissolved by ground
water. The Mahogany zone impedes the flow of water
between the aquifers, and large chemical differences
have developed. Water in the upper aquifer generally
contains less than 2,000 mg/l dissolved solids, where-
as the water in the lower aquifer exceeds 30,000
mg/l dissolved solids in the northern part of the
basin.

Digital models were used to simulate the hydro-
logic system. A watershed model was adapted to the
drainage above the gage on Piceance Creek below
Ryan Gulch to evaluate the possible effects of pre-
cipitation changes on the hydrologic system due to
the introduction of atmospheric pollutants from oil-
shale development or from cloud seeding. Each 10-
percent change in precipitation was found to result
in a 40-percent change in ground-water recharge.

100

The model study indicates that a 10-percent decrease
in October-May precipitation results in a 30-percent
decrease in mean annual runoff, whereas 10- and 20-
percent increases in precipitation result in 40- and
85-percent increases, respectively, in mean annual
runoff.

A digital model of the ground-water system was
used to evaluate the effects of mine dewatering on
the hydrologic system. Hypothetical mines in oil-
shale lease tracts C-a and C-b were considered. Both
mines were assumed to be in the Mahogany zone and
to be 10.4 km2 in area. Dewatering of the mines was
assumed to occur simultaneously for a period of 30
yr. For the hypothetical dewatering scheme simu-
lated, the model study indicates that the mine in
tract C-a will not produce enough water to meet the
demand for processing and disposal of oil shale,
whereas the mine in tract C-b will produce water in
excess of the demand. The concentration of dissolved
solids in the water discharged from the mines may
not exceed 5,000 mg/l for the hypothetical dewater-
ing scheme considered.

Dewatering the hypothetical mines will affect
ground-water discharge in the Yellow Creek drainage
only slightly. However, the model indicates that,
after 30 yr of dewatering, ground-water discharge
would cease in a 16-km reach of Piceance Creek near
tract C-b. The decrease in ground-water discharge in
this reach could cause an increase in the concentra-
tion of dissolved solids in the downstream reach of
Piceance Creek. After 30 yr of dewatering, the hy-
draulic head in the aquifers would be decreased in 75
percent of the basin area, and about 620 hm“ of
water would be removed from storage in the
aquifers.

Large ground-water reservoirs discovered in Rocky Mountain

National Park

According to F. A. Welder and R. A. McCullough,
seismic traverses in valleys in the northwestern part
of the Rocky Mountain National Park (about 260
kmfl) indicate that Quaternary glacial and alluvial
deposits are as much as 122 m thick and contain as
much as 1,230 hm3 of ground water. Ground water in
the park is essentially a calcium and sodium bicar-
bonate type. Specific conductance of the ground wa-
ter ranges from about 100 to 300 ,lmho/cm at 25°C;
the specific conductance of surface water is usually
less than 100 ymho/cm. Aquifer tests in four wells
tapping Quaternary deposits indicated transmissivi-
ties of 2.5, 75, 290, and 440 mZ/d.

 

GEOLOGICAL SURVEY RESEARCH 1975

KANSAS

Recharge-discharge relation in the Great Bend Prairie

In an investigation of water resources in the Great
Bend Prairie, S. W. Fader and L. E. Stullken found
that natural recharge to the ground-water reservoir
averages about 300 hm3/yr in the 5,800-km2 area.
The recharge is equivalent to about 50 mm of water
over the entire area. Withdrawals of ground water
for irrigation in 1974 amounted to about 170 hm“,
which was applied to about 10 percent of the land in
the Great Bend Prairie. The withdrawals exceed the
recharge rate in the irrigated area, but water levels
in wells generally recover between pumping seasons
because total withdrawals do not yet exceed total
recharge.

Availability of ground water in Ness County

Results of a reconnaissance study of the water re-
source-s of Ness County by E. D. Jenkins and M. E.
Pabst showed that water for irrigation and municipal
supplies in the county is obtained principally from
wells in the Pawnee River and Wet Walnut Creek
valleys. Fifteen municipal wells and 160 irrigation
wells are located in alluvium in the stream valleys.
Wells in the Pawnee River valley reportedly yield 6
to 76 l/s. Wells in the Wet Walnut Creek valley yield
from 2 to 321/s.

The eastern edge of the Ogallala Formation, which
is the principal aquifer in western Kansas, crosses
Ness County. However, only 15 municipal or irriga-
tion wells tap the formation because well yields from
the Ogallala in Ness County are marginal (maximum
of 131/5) for these uses.

An irrigation well that reportedly yields 82 Us and
several domestic and stock wells tap the Dakota For-
mation, which underlies Ness County. Water from
these wells generally is unsuitable for irrigation be-
cause it contains high concentrations of sodium.

Ground-water withdrawals for irrigation cause water-level

declines in west-central Kansas

The rate of water-level decline is increasing in
west-central Kansas, according to M. E. Pabst and
E. D. Jenkins (1974). From 1950 to 1966, the average
rate of decline was 0.2 m/yr. Records from 1966 to
1974, however, show that the average rate has in-
creased to 0.4 m/yr. The increased rate of decline is
attributed primarily to the effect on water levels of
the rapidly expanding development of ground water
for irrigation. Annual withdrawals of ground water
for irrigation in west-central Kansas have increased
from about 50 hm3 in 1950 to 560 hm3 in 1973.

WATER-RESOURCE INVESTIGATIONS

Planning for prevention of water shortages during droughts in

eastern Kansas

Results of a study of public water supplies in 43
counties’in eastern Kansas showed that water-supply
improvements are needed in many towns and rural
water districts to prevent shortages in future
droughts. H. G. O’Connor (Kansas Geological Sur-
vey) found that many of the smaller towns and dis-
tricts do not maintain basic records of static and
pumping water levels in wells or of changes in well
yields as water levels decline during droughts. A pro-
gram for preventing shortages has been proposed
that includes (1) test drilling and water sampling to
determine the quantity and quality of ground water
available and to guide planning and development as
water needs increase, (2) regular measurements of
water levels and well yields to determine the per-
formance of wells and aquifers, and (3) periodic
evaluation of the records to anticipate impending
shortages.

Statistical techniques used to estimate ground-water withdrawals

in the Great Bend Prairie, south-central Kansas

Because accurate information on annual ground-
water withdrawals needed by State and local plan-
ning and management agencies in Kansas is unavail-
able, various methods of estimating withdrawals are
being investigated. For the Great Bend Prairie, L. E.
Stullken and S. W. Fader obtained promising results
by using statistical analyses of data from 32 wells
randomly selected from a total of 1,160 irrigation
wells in an area of 14,000 kmg. On the basis of re-
peated measurements of discharge from the sample
wells, Withdrawals for irrigation were estimated to
be about 148 hm3 in 1974. The statistical analyses
indicate a 7 0-percent probability that the estimate is
within 15 percent of the true value. The analyses also
indicate that a 90-percent probability could be ob-
tained for the same accuracy level if 100 wells were
included in the sample.

Effects of pumping ground water from wells in the Dakota

Formation in Ford and Hodgeman Counties

Between 9.5 and 18.5 hm“ of ground water was
pumped from irrigation wells in the Dakota Forma-
tion in Ford and Hodgeman Counties in 1973. Accord-
inng to E. C. Weakly (Kansas Geological Survey),
the water, which was used to irrigate 3,120 hm'l,
occurs primarily in sandstone lenses in the forma-
‘tion. Well yields and effects of pumping depend on
the thickness, areal extent, cementation, and hy-
draulic connection of the sandstone lenses. The water
is confined in some areas but unconfined in others.

 

101

Water-level fluctuations differ greatly in response to
the degree of confinement and quantity of water
pumped. Water-level declines in wells in the counties
ranged from 0 to 12 in during the period 1968—74.

LOUISIANA

New sources of fresh ground water discovered in St. James

Pafish

D. C. Dial reported that results of test drilling in
St. James Parish along newly completed Interstate
Highway 10 in a previously inaccessible backswamp
area showed that water in the upper part of the re-
gional Gonzales-New Orleans aquifer is suitable for
public-supply use but that the lower part of the
aquifer contains salty water. This fact is the first
information on the southern limit of freshwater in
the aquifer in St. James Parish.

New information for another site about 3 km
northeast of Gramercy indicates that the Gramercy
aquifer contains freshwater in an area where it was
previously believed to contain slightly saline water.
However, the areal extent of this zone of freshwater
and the relations with the zone of slightly saline
water have not yet been determined.

Quality of the Red River

Treated and raw municipal waste is discharged in-
to the Red River at several locations between Shreve-
port and Moncla. Results of studies by D. E. Everett
indicated that fecal coliform concentrations exceed
1,000 colonies per 100 m1 most of the time and occa-
sionally exceed 10,000 colonies per 100 ml. The high-
est concentrations generally occur downstream from
Shreveport. On May 8, 1974, the fecal coliform con-
centration at Coushatta was 31,000 colonies per 100
ml.

New information on shallow aquifers in the Baton Rouge area

Recharge to the “400-ft” and “GOO-ft” sands, the
principal aquifers in the Baton Rouge area, occurs
mainly in an area of about 1,600 km2 that is centered
approximately 40 km north of Baton Rouge. Results
of a study by A. J. Gogel indicated that water levels
in the recharge area probably are not affected by
heavy pumping in the Baton Rouge area; rather,
water-level trends in the recharge area tend to reflect
precipitation trends.

The initial pumping test of a large-capacity well
in.the recharge area indicated that the transmissivi-
ty is about 660 mg/d, the hydraulic conductivity
about 18 m/d, and the storage coefficient about
4 X 10".

102

Ground-water quality in Lake Charles area

According to D. J. N yman, two bodies of water in
which the chloride concentration ranges from 50 to
440 mg/l have been defined in the “500-ft” sand of
the Chicot aquifer in the Lake Charles industrial area
of southwestern Louisiana. The bodies occur along
the sides of a cone of depression resulting from in-
dustrial pumping about 10 km southwest of Lake
Charles.

The source of the chloride in the water is appar-
ently unrelated to industrial discharge; however,
movement of saline water into the cone of depression
is related to changes in the ground—water gradient as
the cone of depression deepens. It is believed that the
source of the saline water is isolated pockets con-
tained in natural sedimentary traps at the bottom of
the aquifer. The water in adjacent aquifers (“200-
ft” sand and “700-ft” sand) and confining clays has a
chloride concentration of less than 100 mg/l; the
water in the aquifer between old oilfields to the
northeast and the saltwater interface to the south
generally has chloride concentrations of 20 to 50
mg/l.

Storage changes in the terrace aquifer in central and northern

Louisiana

The increas‘éd ground-water storage in the terrace
aquifer of central and northern Louisiana that re-
sulted from abovenormal rainfall during 1973 and
1974 could be beneficial to water users by increasing
short-term supplies, according to T. H. Sanford, Jr.
However, when long-term supplies are being planned,
water users should take into account that storage
varies with rainfall trends and decreases during peri-
ods of rainfall deficiency. Long-term v'vater-level rec-
ords indicate that as levels decline from high stages
to levels typical of deficient rainfall periods, well
yields may decrease as much as 25 to 35 percent.

Availability of ground water in the upland terrace aquifer,

Bossier Parish

The terrace aquifer has not yet been used as a
source of water for public-supply wells in most of the
area of suburban development in southern Bossier
and southwestern Webster Parishes. However, the
Wilcox aquifer, the present source of public supplies,
may not be able to meet all future demands. Analyses
of water samples from test holes installed in the ter-
race aquifer during site studies by J. L. Snider indi-
cated that in some localities the aquifer contains
water with an iron concentration greater than 0.3
mg/l and a hardness greater than 180 mg/l but that
in other localities the water has low concentrations

 

GEOLOGICAL SURVEY RESEARCH 1975

of iron and hardness. The yields of two new public-
supply wells in the terrace aquifer were 9.1 and 10
l/s. The sustained yield to continuously pumped wells
in the terrace aquifer is estimated to be about 2.4
l s—1 kin—2.

Effect of Hurricane Carmen on water quality in Atchafalaya
River basin

According to F. C. Wells, water quality in the
southeastern part of the Atchafalaya River basin
was affected by Wind and rain associated with Hurri-
cane Carmen, which passed just west of the basin on
September 7 and 8, 1974. A deterioration in water
quality was noted in an area south of Little Bayou
Pigeon and east of the main channel of the Atcha-
falaya River.

On September 17, 1974, DO concentrations were
less than 0.5 mg/l at] five key stations in the back-
swamp area of the basin: The pHvalue of the water
at the five stations was 6.6, sulfide concentrations
ranged from 0.5 to 4.1 mg/I, and BOD concentrations
ranged from 4.1 to 6.5 mg/l.

On October 11, 1974, a reconnaissance of the five
key stations in the basin showed that concentrations
of DO ranged from 0.5 to 3.3 mg/l, pH values ranged
from 6.8 to 7.2, sulfide concentrations were less than
0.5 mg/l, and BOD concentrations ranged from 1.2
to 1.9 mg/l.

The degradation in quality on September 17 proba-
bly resulted from (1) a large amount of biodegrad-
able organic matter from the bed material of the
relatively shallow bayous that was put into suspen-
sion by wave action from Hurricane Carmen and (2)
organic matter along the banks that was washed
into the bayous by runoff created by the rainfall
accompanying Carmen.

Water quality of the Red River alluvial aquifer

M. S. Whitfield, Jr., reported that chemical analy-
ses of samples collected from 185 wells during 1974
indicate that the Red River alluvial aquifer normally
yields water that is hard and has a very high con-
centration of iron. In 12 small areas, water in the
alluvium contains excessive concentrations (>250
mg/l)_ of chloride and sulfate. The following-table
shows the general ranges and the extreme ranges of
the more troublesome chemical constituents:

Typical 'rrmges (mg/l) Extreme ranges (mg/l)

Low High Low H ig‘h
Hardness _________ 300 600 28 1,100
Iron _____________ 3 1 0 0.05 40,
Chloride __________ 1 0 80 0.4 4,600
~ Sulfate ___________ 10 96 0 870

WATER-RESOURCE INVESTIGATIONS

Only 11 of the wells sampled produced water that
was either soft (<60 mg/l of hardness) or low in
iron concentration (<0.3 mg/l), and only one well
produced soft water with a 10W iron concentration.
The water of better quality can be related to rapid
infiltration or precipitation, lateral and vertical flow
from adjacent units, or recharge from streams dur-
ing high stream stage.

MONTANA

A hydrologic study of the Flathead Indian Reservation

Mission Valley, on the eastern side of the Flathead
Indian Reservation, is underlain by Quaternary glaci-
al deposits. The glacial deposits range from slightly
permeable silt and clay (lakebed deposits) in the
middle of the valley to permeable sand and gravel
along the mountain front to the east. According to
A. J. Boettcher, losses in streamflow result when
streams flow from the Precambrian rocks of the
Mission Range onto the coarse glacial deposits. The
recharge water moves through the coarse deposits
toward the middle of the valley Where the aquifer is
confined by the overlying lakebed deposits. Flowing
wells have been developed from the coarse deposits
in the Ronan area. Artesian springs are found in
places where the lakebed deposits are thin or have
been eroded away.

Ground water in the Libby area

An appraisal by A. J. Boettcher and K. R. Wilke of
ground water in the Libby area of northwestern
Montana indicated that the aquifer system (alluvial
and glacial deposits of Quaternary age) could sup-
port increased ground-water Withdrawal. An aquifer
test indicated that transmissivity is about 370 mz/d,
and the well yield is more than 30 1/5.

Analyses of water samples from 91 wells show that
the ground water is suitable for domestic supplies.
However, some relatively high concentrations of ni—
trate (1.5 to 29 mg/l) in rural areas undergoing
heavy residential growth indicate the presence of
septic—tank effluent in ground water.

During an unseasonable flood in January 1974,
maximum flows for most of the smaller streams
equaled or exceeded a 50-yr flood, and water levels in
wells along creeks rose markedly.

Ground-water study in a potential strip-mining area near Ashland

A study of the reclamation potential of strippable
coal deposits in southeastern Montana was conducted
by W. R. Hotchkiss on about three sections of coal-
rich land between Threemile and Home Creeks, tribu-

 

103

taries to Otter Creek near Ashland. The Knoblock
coal unit, about 18 m thick, and 13 lesser coal seams
of the Tongue River Member of the Fort Union For-
mation of Paleocene age are the major shallow aqui-
fers in the area. Ground water flows west to south-
west through the area and discharges to the bound-
ing streams. The yield of water to wells from the
Knoblock coal unit ranges from 0.2 to 0.3 1/ s; specific
capacity is about 0.02 l s*1 m“. Major constituents
in water from the coal are sodium and bicarbonate or
sodium and sulfate; the dissolved-solids concentra-
tion ranges from 1,210 to 4,090 mg/l.

A digital-computer model will be utilized to esti-
mate the response of the local hydrologic framework
to various stages and intensities of strip mining.

Flowing wells can be completed in Madison Group

W. R. Miller reported that flowing wells can be
complete-d in the Madison Group in part of the Fort
Union coal region south of the Yellowstone River. A
preliminary potentiometric surface map, based on
data from drill-stem tests, shows that water levels
range from 90 m to more than 240 m above land sur-
face along the Powder and Tongue Rivers. However,
in the interstream areas, the potentiometric surface
ranges from about 60 m to as much as 300 m below
land surface.

Shallow aquifers above the Pierre Shale

Investigations looking into the hydrologic effects
of strip mining of coal in southeastern Montana indi-
cated that several aquifers exist above the Pierre
Shale. According to R. S. Roberts, B. D. Lewis, and
J. D. Stoner, the Fox Hills-basal Hell Creek aquifer
overlies the Pierre and locally yields as much as 12
1/ s of water to wells less than 300 m deep. The upper
Hell Creek Formation may yield 3 1/3 to wells gen-
erally less than about 240 m deep. Overlying the Hell
Creek is the Fort Union Formation, Which consists of
three members. The upper unit, the Tongue River
Member, contains discontinuous sandstone and coal
beds that form the aquifer usually developed for do-
mestic and stock supplies. Yields to wells are gen-
erally less than 3 1/3 at depths less than 150 m.
Alluvium along major valleys is reported to yield
as much as 45 US to wells 18 m deep; however, most
yields are less than 61/s.

NEBRASKA
Stream-aquifer models for basinwide resource planning, Platte
River basin

The limits of .the water-resource potential of the
105,700-km2 Platte River basin were described by

104

means of digital models, according to E. G. Lappala.
Because of the large size of the area and the detail
desired, the basin was divided into five subbasins,
each of which was modeled and integrated into the
whole. Models used were finite—difference ground-
water-flow models that incorporated features of base
flow and evaporation salvage. Steady-state methods
were used to calibrate four of the models by compar-
ing computed recharge and discharge with historical
precipitation and streamflow. The fifth model was
calibrated by comparing transient water level
changes. Net recharge or discharge for calibration
and predictive analyses were computed by means of
a model of monthly rainfall versus runoff and soil
moisture. Water—resource development has been un-
derway in the basin for nearly a century, first by
stream diversion and later by ground—water with-
drawal. At the present time, 3,240 km2 is irrigated
by stream diversions and 6,070 km2 is irrigated by
ground water, and it is projected that 16,000 km2
will be irrigated by ground water by the year 2020.
Results of the study are to be used in a comprehen-
sive plan for water-resource management of the
Platte River basin in Nebraska.

NEW MEXICO

Geothermal hydrology of the Jemez Mountains

According to F. W. Trainer, ground-water data for
the southwestern part of the Jemez Mountains vol-
canic mass in north-central New Mexico suggest that
much of the subsurface drainage from Valles caldera
follows marginal faults at the western side of the
Rio Grande rift zone. (The mountain mass stands
astride the marginal fault zone.) Thermal springs
and several cold springs and wells in San Diego Can-
yon, some of them near or associated with faults,
yield waters believed to be mixtures of NaCl thermal
water and shallow nonthermal ground water. The
presence of thermal springs, together with observa-
tions in the canyon just outside the caldera rim—
temperature observations in a well and the presence
of a small fumarolic area—indicate active subsurface
drainage of thermal water. This drainage contributes
substantially to the chemical load of water in the
J emez River and in its alluvium by adding constitu-
ents, such as As, B, Cl, F, and Li, that are considered
characteristic of volcanic water. In a few places, con-
centrations bf the minor constituents have been
found to exceed amounts established by the USPHS
for potable water.

 

GEOLOGICAL SURVEY RESEARCH 1975

NORTH DAKOTA

Geohydrology of formations of Cretaceous and Tertiary age in

Morton County

D. J. Ackerman investigated the availability and
quality of water from aquifers in formations of Late
Cretaceous and Tertiary age in Morton County. The
aquifers are very fine to medium-grained sandstones
that are interbedded with and grade into siltstones
and silty shales. The formations dip to the northwest
at a rate of about 2 m/km. Ground-water movement
is generally eastward toward major discharge areas
in the deep valleys of the Heart, Cannonball, and
Missouri Rivers. The quality of water from these for-
mations varies within individual aquifers and from
one aquifer to another.

The hydrologic conditions within these formations
are highly variable. However, a preliminary analysis
of the collected data indicates that differences may
be predictable.

Spiritwood aquifer extends into LaMoure County

C. A. Armstrong reported that test drilling in
Dickey and LaMoure Counties has shown that the
Spiritwood aquifer extends from the northern border
of LaMoure County to the southeastern part of the
county. The aquifer averages about 10 km in width
through much of the county and generally ranges
from about 10 to 40 m in thickness. Estimates of well
yields, based on aquifer thickness and the grain size
of the material in the aquifer, indicate that as much
as 160 l/s can be obtained in some of the thicker
parts of the aquifer. Yields of about 65 to 95 l/s
should be obtainable from most of the central part of
the aquifer. Analyses of two water samples show
that the water is a very hard, sodium-bicarbonate
type containing 732 and 911 mg/l of dissolved solids.
Iron and manganese concentrations are high, and the
sodium-adsOrption ratios in the two analyses are 3.4
and 4.9.

Availability of ground water from lignite

R. L. Klausing reported that data collected during
investigations of ground-water resources in Dunn
County indicate that the majority of water wells
drilled in the county are completed in lignite beds in
the Sentinel Butte Member of the Fort Union Forma-
tion. The water-bearing lignite beds tapped by wells
range in thickness from about 1 to 6 m. Yields from
these wells, generally ranging from about 0.5 to 6
l/s, are adequate for stock and domestic purposes.
Data from aquifer tests indicate that locally some of
the lignite aquifers may yield from 1.9 to 6.3 l/s.

VVATER-RESOURCE INVESTIGATIONS

Short-term tests in two lignite aquifers gave trans-
missivities of about 70 and 1,800 mz/d.

Extensive aquifer in Grant and Sioux Counties

P. G. Randich reported that test drilling in Grant
and Sioux Counties has shown that the Fox Hills
Sandstone is the most extensive aquifer in the two-
county area. It crops out in the southeastern part of
the area (Sioux County) and lies about 300 m below
the landsurface in the northwestern part (Grant
County). Estimated potential yields to wells pene-
trating the aquifer range from about 0.2 to 10 l/s.
Dissolved solids in 27 samples analyzed ranged from
296 to 2,020 mg/l and averaged 1,310 mg/l.

OKLAHOMA

Appraisal of ground water in the (Barber-Wellington aquifer,
central Oklahoma

Results of a study by J. E. Carr of the Garber-
Wellington aquifer within the area between the
Cimarron River and the North Canadian River indi-
cated that there is a considerable quantity of water
in storage. The aquifer supplies water for municipal,
industrial, and domestic use. The maximum yield for
deep wells is about 30 Us and the average yield is
about 15 l/s. Yields from shallow wells are generally
about 2 to 6 l/s.

The lower part of the aquifer contains brackish or
saline water. The thickness of the freshwater inter-
val (water with a dissolved-solids concentration of
less than 1,000 mg/l) in the aquifer ranges from
about 30 m north of Cottonwood Creek to about 240
m near Oklahoma City.

Well data in the outcrop area indicate that water
generally is unconfined in the upper sands and that
artesian conditions prevail in the deeper sands. Data
show a water-level mound between Cottonwood Creek
and Deep Fork. Ground water is discharged to most
of the larger streams in the outcrop area.

Availability and quality of ground water in the Vamoosa aquifer

J. J. D’Lugosz reported that the Vamoosa aquifer
underlies an area of about 6,480 km2 in central Okla-
homa and furnishes water for domestic and indus-
trial uses and municipal supplies. However, the
amount of water used is a small fraction of the total
available.

Because of the variation in lithology, sorting, and
grain size, porosity in the aquifer ranges from less
than 10 percent to about 30 percent. Recovery tests
show the aquifer to range in transmissivity from 28

 

105

to 46 m‘Z/d and the hydraulic conductivity to vary
from 2 to less than 1.5 m/d.

Water in the upper part of the Vamoosa aquifer is
fresh; dissolved-solids concentrations usually are less
than 500 mg/ 1. The lower part of the aquifer, how-
ever, contains brackish or saline water. The zone con-
taining water with a dissolved-solids concentration of
less than 1,500 mg/l ranges from nearly 0 to about
220 m in thickness. In most of the area, water in the
Vamoosa aquifer is a bicarbonate type containing
less than 50 mg/l of sulfate or chloride. Locally,
however, bromide-chloride ratios show that the aqui-
fer has been invaded by saline water.

Investigations of ground-water supplies in the Antlers Sand,
southeastern Oklahoma

Data compiled by D. L. Hart, Jr., showed that the
Antlers Sand of Hill (1894) (Cretaceous) in southern
Oklahoma has considerable quantities of water in
storage. The areal extent of the aquifer is about
10,360 kmg, and thickness ranges from about 0 to
275 m. In about half the area, water in the aquifer is
confined; in outcrop areas, however, the water is un-
confined. The maximum measured well discharge is
41 US, but average well yields are about 151/s.

Recharge to the aquifer from precipitation occurs
throughout most of the outcrop area. Discharge oc-
curs primarily by ground-water losses to tributaries
of the Red River, but some water is pumped from
the aquifer for municipal and industrial uses. Addi-
tional quantities leave the area by downdip move-
ment to Texas, and some water is discharged from
flowing wells in the Vicinity of the Red River.

The water in the outcrop area generally is a sodi-
um-bicarbonate type containing less than 1,000 mg/l
of dissolved solids. Locally along the Red River and
in southeastern McCurtain County, the water is a
sodium-chloride type containing more than 3,000
mg/l of dissolved solids.

SOUTH DAKOTA

Development of aquifers in north-central South Dakota

An estimated 8 million litres of water per day are
withdrawn from glacial-outwash aquifers in Faulk,
Edmunds, and McPherson Counties, an 8,500-km2
area in north-central South Dakota. L. J. Hamilton
reported that the pumpage, because it is evenly dis-
persed over the area and is only a small fraction of
the annual recharge, has no large or lasting effects
on water levels. Several aquifers in the area can sup-
ply wells yielding from 6 to as much as 60 VS.

106

The very hard water from shallow glacial aquifers
generally is of suitable quality for irrigation, since
its sodium content averages less than 50 percent of
the cations and its dissolved-solids concentration
averages only about 800 mg/l. Water from deep
glacial aquifers also is very hard but is unsuitable
for irrigation because of a high sodium content (>50
percent of the cations) and a dissolved-solids concen-
tration averaging about 1,300 mg/l.

Withdrawals of water from bedrock aquifers,
mostly sandstone, are estimated to be 22 million
litres per day. Since 1880, water levels have declined
more than 76 m in wells in the Dakota Sands-tone.
Similar declines can be expected for the deeper high-
pressure aquifers now being developed unless flows
are carefully restricted. The water from the bedrock
aquifers is not of suitable quality for irrigation use.

Test drilling in northeastern South Dakota

Aquifers in glacial-outwash deposits were pene—
trated by 25 of the 50 test holes drilled in 1974
in Clark County, a 2,500-km2 area in northeast:
ern South Dakota. According to L. ‘J. Hamilton
(USGS) and C. N. Christensen (South Dakota Geo-
logical Survey), the thickness of most of the outwash
is less than 9 m. However, test holes in 5 widely
spaced areas penetrated as much as 18 m of medium
to coarse sand and gravel. The age of the outwash is
considered to be younger than late Wisconsin because
the outwash is overlain by up to 70 m of till. As
much as 20 m of the till has been oxidized to a yel-
lowish-brown color during a period of interglacial
weathering.

Shallow glacial aquifer delineated in Hand County

A shallow glacial aquifer in northeastern Hand
County has been delineated as a result of a test drill-
ing program directed by N. C. Koch (USGS) and Ron
Halgerson (South Dakota Geological Survey). The
sand and gravel aquifer underlies an area of about
780 kmg, principally in the main drainageways of
Medicine, Wolf, and Turtle Creeks. The sand and
gravel bodies in these drainages are interconnected
by a complex system of sand and gravel layers sepa-
rated by gravelly clay. The sand and gravel, which
occurs near the land surface, is about 5 to 27 m thick.
The three creeks derive part of their flow from
ground-water discharge from the aquifer. The aqui-
fer can provide yields of about 10 to 32 VS to wells.
The water is very hard but is of generally suitable
quality for irrigation use. The sodium content is less
than 50 percent of the cations, and dissolved-solids
concentrations are generally less than 2,000 mg/l.

 

GEOLOGICAL SURVEY RESEARCH 1975

Extensivebasal-outwash aquifer in northeastern South Dakota

Test wells, which averaged 159 m in depth at 84
sites in Deuel and Hamlin Counties in northeastern
South Dakota, revealed a buried basal~outwash aqui-
fer that underlies a 1,750—km2 area. Jack Kume re-
ported that sand and gravel penetrated in drilling
ranged in thickness from 1 to 31 .m and was en-
countered at depths of 49 to 250 m. Its average thick-
ness was about 11 m.

The aquifer was mapped as the lowermost outwash
deposit in the thickest (268 m) glacial drift in South
Dakota. It lies upon bedrock—Pierre Shale or Nio-
brara Formation (Upper Cretaceous)—or, in a few
places, upon a thin layer of till adjacent to the bed-
rock.

TEXAS

Exploration for fresh ground water in basins of western Texas

J. S. Gates, D. E. White, and J'. T. Smith drilled.
three deep test holes in the Salt Basin alluvial fill to
determine its saturated thickness and water quality.
The test hole drilled south of Valentine on Ryan Flat
penetrated alluvium to about 120 m, thin volcanic
flows and alluvium consisting mostly of reworked vol-
canic material to about 400 m, volcanic flows and tuff
to about 460 m, and tufi' to 610 m. Four water sam-
ples collected at depths between the water table (69
m) and 350 m were fresh.

The test hole drilled northeast of Van Horn on
Wildhorse Flat penetrated alluvium to about 365 m
and Cox Sandstone of Early Cretaceous age to 400 m.
Water samples collected at depths between the water
table (115 m) and 378 m, including a sample from
the Cox Sands-tone, were fresh.

The test hole drilled southwest of Van Horn on
southeastern Eagle Flat penetrated alluvium that
consisted mostly of clay and silt with thin beds of
sand and gravel to 610 m. Water samples collected at
depths between the water table (about 225 to 268 m)
and 425 m were fresh.

Occurrence of porous evaporitic rocks in the Edwards Limestone

R. W. Maclay and T. A. Small reported that the re- .
sults of studies of newly designated stratigraphic
units of the Edwards Limestone in southern Te‘xas
indicate that some highly porous zones in the Ed-
wards aquifer are associated with the evaporitic rock
Units previously identified by P. R. Rose (1972).
Several cycles of marine to supratidal deposits occur
within the middle third of the Edwards Limestone in
the Bexar County area. A typical cycle originally con-
sisted of a lower, pelleted mudstone unit, a mudstone

WATER-RESOURCE INVESTIGATIONS

and wackestone unit containing algal mats and other
tidal-flat structures, and an upper supratidal unit
containing sucrosic dolomite and nodular gypsum or
anhydrite. These supratidal deposits were exposed on
extensive salt plains or “sebkhas” that were infre-
quently flooded by marine waters, which dissolved
some of the nodular evaporites. The Kirschberg
Evaporite Member (Rose, 1972) is one of the more
laterally extensive units that can be identified from
cores and geophysical logs. After burial and subSe—
quent to faulting, meteoric water gained access to
these rocks along fractures in the subsurface. These
evaporitic units probably contribute much to the
high transmissivity of the Edwards throughout
Bexar and Comal Counties.

Digital-model study of ground-water hydrology in the El Paso area

A digital model of the hydrology of the Hueco Bol-
son near El Paso was constructed by W. R. Meyer to
simulate historical water-level declines and to predict
future water-level declines. The model indicates that
additional water—level declines ranging from about 14
to 21 m can be expected in the area by the year 1991.
The model also indicates that seepage losses from the
Rio Grande will increase from about 14,800,000 m3/
yr to about 19,500,000 m”, yr by 1991.

The model can be used as an aid in determining the
optimum areal distribution of wells, and different
pumping procedures can be simulated to assist in de-
termining a pumping pattern that will result in more
uniform drawdown in the area of production.

UTAH

High transmissivity in northern part of Parowan Valley

According to L. J. Bjorklund and C. T. Sumsion, an
aquifer test in the northern part of Parowan Valley
indicated that the water-bearing material has a high
transmissivity.

Water-level measurements made in March 1974,
before the pumping season, indicated that the poten-
tiometric surface of the ground-water reservoir had
an almost horizontal gradient—about 0.09 m ”km.
Water-level measurements made in October 1974
also indicated a flat potentiometric water-level sur-
face, but it was about 0.6 m lower than the March
surface because water was removed during the irri-
gation season.

An aquifer test in Buckhorn Flats indicated a
transmissivity of about 18,600 m‘-‘ "d; almost uniform
results were observed in nine observation wells in an
area of about 3,240 hmi. An irrigation well was
pumped at rates between 190 and 250 l ”s, and water-

 

107

level observations were made in wells at radial dis-
tances ranging from 900 to 3,700 m. Drawdown of
the water level in a well 900 m distant was observed
within 10 min after pumping began and increased to
0.39 m during 16.4 d of pumping. The maximum
drawdown in the pumped well was 6.1 m. The pumped
well penetrated 125 m of unconsolidated material
consisting of near-surface silt and clay underlain by
silt, sand, gravel, cobbles, and boulders, mostly of
volcanic origin.

WYOMING

Water losses from streams to the Madison Limestone

Thirty—two gaging stations were established on 17
streams in the fall of 1974 in northeastern Wyoming
to collect streamflow data for use in determining po—
tential recharge to the Madison Limestone aquifer.
The outcrop areas are along the northern and north-
eastern flanks of the Laramie Mountains, the eastern
slopes of the Bighorn Mountains, the western part of
the Black Hills uplift, and the Hartville uplift near
Jay Em. More than 50 stream channels were investi-
gated during the geologic and hydrologic field recon—
naissance. F. C. Boner reported that discharge meas-
urements made during the fall of 1974 indicate that
nearly all streams crossing the outcrop areas in the
Laramie Mountains lost water to the aquifer. In the
Bighorn Mountains, about 60 percent of the streams
showed gains and the remainder showed losses; how-
ever, volumes of gains and losses have not yet been
calculated. Streams in the western Black Hills uplift
showed gains.

Geohydrology of the Albin and La Grange areas

In the Albin area, the Ogallala Formation was
found to be saturated only in coarse-grained channel
deposits from which most of the irrigation wells
pump, according to W. B. Borchert. Water levels in
parts of these channel deposits have declined about
1.2 to 2.1 m since pumping began in 1968. However,
in the area southeast of Albin, about 1.2 m of the 2.1
m of decline can be attributed to a 170-percent in-
crease in ground-water pumpage between 1973 and
1974.

In parts of the La Grange area, the net effect of
ground-water pumpage and surface-water recharge
since 1969 has resulted in a rise of about 1.2 m in
water level. In two large-diameter wells drilled into
the Brule Formation, secondary porosity was located
by using caliper logs and acoustic borehole televiewer
logs. Geophysical logs were run in these wells. At
known depths of secondary porosity, the response of

108

the geophysical logs to secondary porosity in the
Brule Formation was evaluated and a basis for future
comparisons established.

Hydrologic analysis of the valley-fill aquifer, North Platte River

valley, Goshen County

Water-level measurements taken in observation
wells indicated that little change in storage occurred
in the valley fill in Goshen County during a 1-yr peri-
od. M. A. Crist (1975) reported that annual recharge
to ground water from precipitation, seepage from
canals, and seepage from surface-water irrigation
amounts to about 89.4>< 106 m3 and is nearly equal to
the 94.1 X 100 m3 estimated as the ground-water con-
tribution to the North Platte River. The valley fill is
estimated to contain about 2.1><109 m3 of water in
storage. A digital model developed during the investi-
gation can be used to predict the general effects of
changes in stress that might be applied to the
system.

Impacts of coal development on topography and shallow aquifer

in Gillette area

R. F. Hadley and W. R. Keefer. (1975) reported
that results of studies in an area of about 2,500 km2
in central Campbell County showed that the Wyodak-
Anderson coal bed is less than 60 m below land sur-
face in approximately 30,000 ha and less than 90 m
below land surface in an additional 13,500 ha. Topo-
graphic cross sections have been prepared to show
some of the broad~scale changes that can result from
surface mining. For example, if a “swell” factor of
25 percent is assumed, the surface would be IOWered
about 19 m in those areas where the coal bed is 30 m
thick beneath an average overburden of 46 m. Cross
sections also show the inferred effect on the ground-
water system of a hypothetical surface-mining opera-
tion. Water levels in wells tapping shallow aquifers
may be substantially lowered within about 6 km of
individual mining operations. Determining the
longevity of the lowered ground—water levels and
their possible recovery to premining levels will re-
quire monitoring of wells under actual mining
conditions.

Hydrologic investigations related to fossil fuels

R. E. Hodges, Joe Sena, and L. M. MacCary began
a research program on borehole geophysics as applied
to coal-related studies. Coal deposits are easily identi-
fied on the density, neutron, and resistivity logs. In
areas where the coal bed is the aquifer, geophysical
logs will be used to estimate the effective porosity,
and televiewer logs will be used to determine the type

 

GEOLOGICAL SURVEY RESEARCH 1975

and orientation of the fractures. Logging of the
Madison Limestone in Wyoming has been initiated in
coal-related studies to determine the availability of
ground water for coal-slurry operations and coal-
fired steamplant operations. The Madison Limestone
has been logged at depths of about 915 m, but it
attains depths of 3,650 m in the deeper parts of the
Powder River Basin. A newly acquired logging truck
with a capacity of 4,875 m will be used for geophysi-
cal measurements in these areas.

Dye-recovery study in Tongue River Cave

The occurrence of subterranean stream diversion
between two surface-drainage basins on the eastern
flank of the Bighorn Mountains has been established
by a quantitative dye-recovery study conducted in
Tongue River Cave. This limestone cave, located in
Tongue River Canyon, contains a free-surface stream
having a low-flow discharge of 0.04 mg/s.

D. T. Hoxie reported that 396 ml of Rhodamine-
WT dye was introduced into the Little Tongue River
near the point where it sinks into the Bighorn Dolo-
mite of Ordovician age; 35 percent of the injected
dye was eventually detected in the cave stream. The
Little Tongue River is nominally tributary to the
Tongue River; however, under conditions of normal
and low flow, water in the main fork sinks into the
streambed upon flowing onto the Bighorn Dolomite;
this reach is located approximately 4 km south of the
cave and is some 760 m higher in elevation. The
sharply peaked dye-recovery curve suggested the
presence of a single solution conduit linking the cave
and the sink. The time required for the dye to travel
from its injection point into the cave was approxi-
mately 24 h.

WESTERN REGION

Water-resource studies in the western region cov-
ered a wide range of topics, and both old and new
instruments and techniques were used to accomplish
objectives.

The increasing need for real-time data for (1) the
daily operation of river systems for flood forecasting
and warnings and (2) the determination of water-
quality parameters has resulted in expanded pro-
grams in several States but primarily in the Colum-
bia River basin. Radios, direct~line telemetry, and
the transmission of data by satellite are among the
techniques now in use at many sites.

The intensive water-quality assessment of the
Willamette River basin in Oregon is a successful pilot

WATER—RESOURCE

effort to define the basin’s past and present quality
and to develop mathematical models to project quali—
ty conditions under alternative plans for basin de-
velopment. Results of this work‘ will provide bases
for similar assessments of other river basins across
the Nation.

Ongoing programs include the following: (1)
Quantification of geothermal resources at known geo-
thermal areas, (2) San Francisco Bay region en-
vironment and resources planning study, (3) studies
to define the areas inundated by 100- and 500-yr
floods for flood-insurance purposes, and (4) collec-
tion and analyses of data for surface and ground
water and water quality.

M U LTISTATE STU DIES

Great Basin ground-water appraisal

As one of a number of summaries of the Nation’s
ground-water resources (Pacific Southwest Inter-
Agency Committee, 1972) , an appraisal was made of
ground-water resources in the Great Basin by T. E.
Eakin, Donald Price, and J. R. Harrill. They re-
ported that ground-water withdrawals from wells in
the Great Basin region were about 1.4 km3 in 1970.
The region could sustain an annual net pumpage of
about 3.2 km3. Larger withdrawals could be sustained
‘if only part of the pumped water is used consump-
tively, if conflicts with existing surface-water rights
are resolved, and if extensive treatment, artificial re-
charge, and reuse of water prove feasible. Ground
water stored in the upper 30 m of the saturated de-
posits of the valley ground-water reservoirs is on the
order of 370 kmg. Total ground-water storage exceeds
several thousand cubic kilometres.

Similar appraisals have been started in the Lower
Colorado River basin and in the Pacific Northwest,
and an appraisal of the California region is nearing
completion.

ALASKA

Channel erosion surveys

Channel surveys and low-altitude vertical aerial
stereophotography at 24 sites along the trans—Alaska
pipeline route in central Alaska were used to docu-
ment topography before construction. Resurveys and
photography were obtained after partial construc-
tion of a haul road and construction camps for the
pipeline. J. M. Childers (1972) reported that gravel
extraction from flood plains has removed large areas
of flood-plain vegetation and formed deep and exten-
sive floodway basins. The haul road constricts flood-

 

INVESTIGATIONS 109
ways and may concentrate floodflow to promote or
accelerate channel erosion.

Gas-saturation studies at salmon-rearing sites

G. A. McCoy collected gas-saturation data at the
following locations: Crystal Lake hatchery near
Petersburg; Fire Lake hatchery near Eagle Riveri
several streams in south-central Alaska; and at rear-
ing pens at George Inlet near Ketchikan, Starrigavan
near Sitka, and Halibut Cove Lagoon. The three rear-
ing pens are in a gravel-bed stream, saltwater, and
an estuary, respectively.

Data on saturation of nitrogen and DO have been
obtained. Measurements for methane have been
made, but none has been detected. Significant super—
saturation of dissolved gases has been found only at
the Crystal Lake hatchery.

Hydrologic and limnologic investigation of the Karluk River basin

G. A. McCoy and D. R. Scully collected streamflow,
chemical, and physical data for streams and lakes in
the Karluk River basin on Kodiak Island. Three
stream-gaging and water-temperature recording sta-
tions have been established on tributaries to Karluk
Lake. Chemical and physical data were collected on
tributaries to Karluk Lake, Karluk Lake itself, Kar-
luk Lake outlet, and Thumb Lake. Preliminary re-
sults indicate that water quality is good in this area.
Karluk Lake is oligotrophic, and conductance of wa-
ter in all streams is less than 100 ’11th at 25°C.

Hydrologic reconnaissance of St. George Island

G. S. Anderson conducted a hydrologic reconnais-
sance to determine the potential for developing pot-
able ground water on St. George Island. Existing
wells, which produce saline water, are believed to be
either too deep or too close to the ocean. The fresh
ground-water lens is thought to be thin because the
island is small, the rocks are permeable, and recharge
is low. However, it should be possible to skim limited
quantities of fresh ground water if new wells are
drilled farther inland and reach the freshwater lens.

ARIZONA

Effects of vegetation change on water and sediment yield

Precipitation, streamflow, and sediment data were
collected from two similar watersheds in the Syca-
more Creek area to define changes that may take
place in runoff and sediment yield if the dense native
Chaparral in one of the watersheds is replaced by
gra'ss. Each watershed occupies about 11.7 kmg, and
their physiographies and climates are similar. Ac-

110

cording to H. W. Hjalmarson, analyses of streamfiow
and precipitation data indicate that any appreciable
change in runoff owing to the replacement of native
Chaparral by grass can be determined quantitatively.
Statistical analyses indicate that under optimum con-
ditions an increase in runoff of as little as 19 percent
may be evaluated at the 95—percent level of confi-
dence. Because the natural variation in suspended-
sediment yield is large, a change caused by a substi-
tution of vegetation is difiicult to assess.

Ground-water resources of southern Navajo County

According to L. J. Mann, the Coconino aquifer that
underlies southern Navajo County furnishes about
46.9 hm3 of water per year to wells. In addition,
about 2.17 hm3 of water is obtained from the Pinetop-
Lakeside aquifer in the southeastern part of the
county, and about 1.23 hm3 is withdrawn from the
alluvium along the channels and flood plains of the
Little Colorado River and its major tributaries. In
the southern part of the area, ground water general-
ly contains less than 350 mg/l of dissolved solids—
mainly calcium, magnesium, and bicarbonate. In the
northern part, however, the water contains from 500
‘ to as much as 68,200 mg/l of dissolved solids—main-
ly sodium and chloride.

The Coconino aquifer includes the Coconino Sand-
stone, the uppermost beds of the underlying Supai
Formation, and the overlying Kaibab Limestone.
Most of the water withdrawn from the aquifer is
used for agricultural and industrial purposes. Sever-
al small cones of depression have formed near the
large agricultural and industrial areas. Although
water-level declines of as much as 15 m have been
measured, declines generally are less than 1.5 m.

The Pinetop—Lakeside aquifer includes a bedded se-
quence of sedimentary rocks, rim gravel, and basaltic
rocks. Ground water in the Pinetop—Lakeside aquifer
and in the alluvium generally is hydraulically sepa-
rated from that in the underlying Coconino aquifer.
The Pinetop—Lakeside aquifer supplies water to re-
sort areas near Pinetop and Lakeside. The alluvium
may yield sufficient quantities of water for irrigation,
but mos-t wells that tap this unit furnish water for
domestic and livestock uses.

Perched ground water in the northern part of the La Posa Plain

According to D. W. Wilkins, two known areas of
perched ground water are present along Tyson Wash
in the northern part of La Posa Plain——one area sur-
rounds the town of Quartzsite and the other is about
13 km south of Quartzsite. The shallow ground water

 

GEOLOGICAL SURVEY RESEARCH 1975

is perched on the Bouse( ?) Formation. In the area
surrounding Quartzsite, the depth to water ranges
from about 8 m below the land surface near Tyson
Wash to 39 m below land surface about 2 km east of
the wash. In the area south of Quartzsite, the depth
to water ranges from 34 to 46 m below the land sur-
face. The perched ground water is recharged from
flow in Tyson Wash. Two flow events in July and
August of 1974 caused water-level rises of as much
as 1.5 m in wells adjacent to the wash. The chemical
quality of the perched ground water is good; dis-
solved-solids concentrations range from about 100 to
700 mg/l.

Geology and ground-water resources of the Sedona area

G. W. Levings identified the Verde Formation, the
Supai Formation, and the Redwall Limestone as the
major aquifers in the Sedona area. Although faults
in the area do not seem to have a significant effect on
ground-water movement, localized fractures, joints,
and solution channels may significantly increase the
secondary permeability of the formations and may
be associated with the increase in well yields. A com-
parison of water levels measured in the late 1950’s
with those measured in the early 1970’s shows that
there has been no water-table decline. The water is of
suitable chemical quality for domestic and municipal
uses and for irrigation; the main constituents are
calcium, magnesium, and bicarbonate.

CALIFORNIA

Madera area ground-water model

A digital-computer simulation model of the
ground-water system in the Madera area of the east-
central San Joaquin Valley was constructed by using
immediately available data. The first attempts at
model calibration quickly demonstrated that signifi-
cant errors existed in available water-level and
pumpage data. According to W. D. Nichols, a reevalu-
ation of water-level data strongly sugggests that the
major cause of poor calibration is pumpage data com-
puted from power consumption. This conclusion re-
quires a complete reevaluation and probably a recal-
culation of pumpage data for the area being modeled.
The model results will assist in designing data-collec-
tion programs to obtain the more reliable data
needed for calibration.

Ground water in Garner Valley

T. J. Durbin reported that Garner Valley is an
intermontane alluvial basin in the San J acinto Moun-
tains. An alluvial aquifer with a surface area of 54

WATER-RESOURCE INVESTIGATIONS

km2 underlies the valley floor. A mathematical repre-
sentation of the aquifer was used to compute average
annual recharge and discharge.

The aquifer is in a state of equilibrium, and re-
charge from precipitation equals ground-water dis-
charge to phreatophytes and to Lake Hemet, a reser-
voir in the northern part of the valley. The average
annual recharge is 2.7 hmz. The average annual dis-
charge to phreatophytes is 1.4 hms, and the average
annual discharge to other minor sources is 0.1 hmg.

Water purveyors in an adj acent drainage basin are
considering the annual export of 0.5 to 1.1 hm3 of
ground water from Garner Valley, which would cause
an equal reduction of the natural ground-water dis-
charge in the valley.

Rainfall-runoff data prepared for urban hydrology‘study in

Poway region

According to J. A. Skrivan, rainfall data at five
sites in the Poway Creek basin covering about 110
km2 and streamflow data at the basin outlet have
been collected since November 1969. All precipitation
and streamflow data were obtained at 5-min intervals
and have been punched on cards for use in a rainfall-

runofl’ digital model. Photographs of the region are

being taken annually to record land-use changes.

Urban runoff and erosion studies in Perris Valley

Since 1969, the effects of urbanization on the hy-
drologic regimen of the Perris Valley area have been
studied. According to R. P. William-s, data collection
emphasizes rainfall-runoff relations, sediment pro-
duction, and general water quality.

Because rainfall was low during most of the proj-
ect, few events are available for analysis. When‘run-
off does occur, sediment concentrations are evaluated
every 15 min at four sites. Suspended-sediment con-
centrations of 10,000 mg/l are common during storm
events.

The results of the study will be used for land-use
planning in other areas of Riverside County.

Isotope study of California ground-water recharge

Several California ground-water basins are being
recharged with surface water imported from north-
ern California. T. B. Coplen 11, L. A. Eccles, and P. A.
Emery investigated the feasibility of tracing the re-
charge water through the ground-water system by
using stable isotopes of hydrogen (D/H) and oxygen
(018/016) . They have found that northern California
water can be differentiated from “native” ground
water in the vicinity of San Jose.

 

111

Nitrate in ground water, Redlands area

According to L. A. Eccles, agricultural develop-
ment and urbanization in the Redlands area depend
on multiple use and reuse of ground water. The re-
cycling of water to the saturated zone has resulted in
degradation of the water, especially by nitrate, most-
ly in the vicinity of agricultural operations and
points of waste discharge. The most probable causes
of nitrate accumulation in the ground water are pre-
viously high application rates of nitrogen on citrus
crops, low soil-denitrification potential, and high in-
filtration rates, aggravated by recycling of ground
water.

Since the advent in the 1960’s of requirements for
leaf analysis of nitrogen-fertilized citrus crops, the
largest source of nitrate in ground water has been
greatly reduced. Some citrus growers irrigating with
water having a high-nitrate content have not applied
nitrogen fertilizer for more than 5 yr. The projected
high cost of nitrogen fertilizer will also serve to
reduce this source, as will the trend toward
urbanization.

The largest potential source of nitrate is the un-
saturated zone. There is a considerable time lag be-
tween the application of nitrogen on the surface and
its appearance at the water table. An experiment by
other researchers on a soil solution taken below the
root zone has shown that with a nitrogen-fertiliza-
tion rate of 390 kg. hm—Z/yr—1 and a leaching frac-
tion of 0.4, there was a nitrate concentration of 198
mg/l. If the water table were to remain static, the
rate of nitrate migration might be low enough to
prevent an increase of nitrate in the saturated zone,
but an increase in the elevation of the water table
would lead to higher nitrate concentrations beneath
areas of previously high nitrogen application.

The most recent nitrate data for the area show a
declining trend, although locally some wells produce
water with nitrate concentrations in excess of 90
mg/l. This trend is expected to continue, although
there may be periodic increases in nitrate concentra-
tions in some wells.

Quality of ground water in western Sacramento Valley

Ground-water samples from 222 wells located on
the western side of the Sacramento Valley were
analyzed for mineral constituents. G. L. Bertoldi re-
ported that results of the analyses show that the
native ground water is of a calcium magnesium bi-
carbonate type with a dissolved-solids content of gen-
erally less than 300 mg/l. Two small areas of sodium-
chloride-type water and four areas underlain by wa-

112

ter having boron concentrations in excess of 0.75
mg/l (the recommended maximum limit for boron-
sensitive crops) were also found. With the exception
of locally high boron concentrations, the water is
suitable for irrigation of almost all types of crops
and generally is of good quality for domestic use.

Storage capacity, ground-water discharge, and ground-water
movement in the Fresno area

Estimates of storage capacity and ground-water
discharge were made for an area of about 344 km2
northeast of Fresno. According to R. W. Page, total
storage capacity in the upper 61 m of the ground-
water reservoir is about 1,357 hm3, and ground-water
discharge from the area is about 74 to 86 hm3/yr.
Water demands for urban use were larger in January
1975 than in January and February 1963, but the
change in water use did not greatly affect the general
direction of ground-water movement between 1963
and 197 5.

Ground-water resources evaluated in the Ocotillo-Coyote Wells

region

J. A. Skrivan reported that the principal source of
recharge for the alluvial aquifer in the Ocotillo-
Coyote Wells area is precipitation in the mountains
to the west and southwest. The general ground-water
movement is from these recharge are-as eastward to
the Salton Sea and southward to Mexico.

Wells in Ocotillo can produce 25 to 32 VS of water
with a dissolved-solids content of about 500 mg/l.
However, just 8 km to the east, the dissolved-solids
content of water from some wells is 18,000 to 24,000
mg/l. The Elsinore fault, which bisects the region in
a southeasterly direction, probably is an effective
ground-water barrier separating the high-quality
ground water in the western part from the poor-
quality water to the east.

Artificial-recharge feasibility in the upper Santa Ana River area

Results of a study of the feasibility of artificial
recharge for the upper Santa Ana River area by
D. H. Schaefer and J. W. Warner indicated that a
maximum of 100 hmg/yr could be recharged. Water
from the State Water Project will be available in a
few years for artificial recharge in this area.

The upper Santa Ana River area is well suited for
artificial recharge because it is largely underlain by
permeable river-channel deposits. Test drilling indi-
cated some local sandy clay layers, but they were not
extensive enough to impede recharge.

 

GEOLOGICAL SURVEY RESEARCH 1975

Ground-water hydrology in Round Valley

Preliminary results of studies by K. S. Muir indi-
cated that there was no overall decline in water levels
in Round Valley between 1951 and 1974. The quan-
tity of ground water pumped from wells in 1974 did
not exceed the yield of the basin, and the ground-
water reservoir remained full. Potential recharge
was rejected as streamflow. '

The quality of the ground water was found to be
excellent for irrigation and had not changed signifi-
cantly since previous studies made in 1951.

Anza-Terwilliger geologic and hydrologic study
W. R. Moyle, Jr., completed a study in the Anza-

' Terwilliger area of Riverside County that included

the Cahuilla Indian Reservation. The study deals
with geology, steady and transient states of ground
water, net depletion of ground water, chemistry of
water, precipitation, and land and water use in the
area. It also includes a complete Bouguer gravity
map, geologic and hydrologic cross sections, and hy-
drographs. The data show that more water was con-
sumed in 1973 within the study area than is being
recharged by average annual precipitation and that
water levels have declined locally as much as 23 m
between 1950 and 1973.

Temecula gravity map

W. R. Moyle, Jr., and D. J. Downing (1975) pre-
pared a complete Bouguer gravity map of the Teme-
cula area in Riverside County in cooperation with the
Joint Administration Committee of the Santa Mar-
garita and San Luis Rey Watershed Planning Agen-
cies to aid in the exploration for and development of
ground-water supplies. The map shows the relative
thickness of alluvial deposits that contain ground
water and areas where the basement complex is near
the surface.

HAWAII

Hydrology and sediment transport, Moanalua Valley

Five years of intensive data collection in Moanalua
Valley resulted in some observations concerning the
rainfall-runoff and rainfall-sedimentation character-
istics of the 8.65-km2 basin (B. L. Jones and C. J.
Ewart, 1973). According to Ewart, average annual
rainfall for the period 1969—73 ranges from 1,700 mm
at the downstream boundary of the project to 4,040
mm near the headwater area. A water budget con-
structed for the upper half of the basin reveals that
runoff, evapotranspiration, and ground-water re—
charge comprise 15, 25, and 60 percent of the annual

W'ATER-RESOURCE

rainfall, respectively. Analyses of the suspended-
sediment data collected from two locations in the
valley indicate a good correlation between total sedi-
ment discharge during a storm and peak discharge.
Observations indicate that the stream frequently
transports very large boulders (in excess of 0.6 m in
diameter).

Water resources of eastern coast of Kauai

Kauai County officials believe that municipal water
supplies under drought conditions are not adequate
to meet increasing demands for water resulting from
urban expansion and resort development in the towns
on the eastern coast of Kauai. Currently, the only
source of domestic supply is ground water from wells
and tunnels. R. J. Burt reported that most of the
pumpiage is from perched-water bodies in the gen—
erally poorly permeable lava flows of the Koloa Vol-
canic Series, the younger of the two major volcanic
rock formations of the island. Recently drilled wells
in the Koloa rocks have not provided the needed ad—
ditional water.

The Koloa lava flows are thick and dense and over-
lie an undefined erosional surface of the older Napali
Formation of the Waimea Canyon Volcanic Series.
The Napali Formation rocks are generally highly
fractured and permeable, but they are considered to
be too deep near the towns for economical develop—
ment of ground water. However, in a few locations,
the Napali rocks protrude as steptoes or “islands”
above the Koloa rocks. These areas have not yet been
fully explored for ground water. A well in the pro-
truding Napali rocks might be effective in draining
water from the Koloa rocks because the “island” of
permeable Napali rocks may act as a giant infiltra-
tion gallery. Water levels in both the Napali Forma-
tion and the Koloa Volcanic Series are high owing to
the confining effect of the Koloa rocks.

Although the streams of Kauai have relatively
uniform and high base flows in comparison with
other streams in Hawaii, ground water has been pre-
ferred for domestic use because it is clear and does
not require treatment.

IDAHO

Effects of pumpage on Thousand Springs

Ground-water withdrawals for irrigation in Good-
ing and Jerome Counties during 1973 were computed
by J. A. Moreland. Pumpage, computed from power-
company records,‘totaled about 105 hm3. A digital
hydrologic model was constructed to simulate water-
level fluctuations and spring discharges in the Snake

 

INVESTIGATIONS 113

River Plain aquifer. The model was successfully cali-
brated for 1966 conditions on the basis of inputs sup-
plied by the Idaho Water Resources Research Insti-
tute. Several alternative water-use plans were simu—
lated on the model to evaluate the effects of the plans
on ground-water levels and spring discharges.

Water resources of Henrys Fork basin above Ashton

The USGS, in cooperation with the Idaho Depart-
ment of Water Resources, is conducting a 2-yr water-
resource investigation of the 2,764—km2 Henrys Fork
basin above Ashton.

R. L. Whitehead, W. A. Harenberg, and H. R. Seitz
reported that monitoring networks for ground-water,
surface-water. and quality-of—water data have been
established to determine the chemical and physical
characteristics of the basin’s water resources. The
basin is in a nearly primal state, but its abundant
recreational features serve to attract an increasing
number of people each year. It is therefore important
to establish a data base from which effects of future
recreational activities and developments can be
evaluated.

Generally, analyses of samples from more than 60
selected sites within the basin indicate that the
water is of excellent quality.

Water resources of the Weiser River basin

A 2-yr investigation of the water resources of the
Weiser River basin was initiated by H. W. Young,
W. A. Harenberg, and H. R. Seitz. The first year’s
effort consisted primarily of the establishment and
operation of monitoring networks to assist in describ-
ing and characterizing the water resources in the
basin. Included in this network are 22 surface-water
measuring sites, 25 ground-water observation wells,
13 surface-water sediment sites, and 3 quality-of-
surface-water sites.

An inventory of approximately 350 wells in the
basin indicates that both artesian and water-table
aquifers are present. Ground-water-level fluctuations
in the basin respond chiefly to spring runoff, surface-
water irrigation, and pumpage for ground-water
irrigation.

A seepage study on the Weiser River indicates that
very little relation exists between the surface- and
ground-water resources except in the lower part of
the basin.

Flow in Silver Creek

J. A. Moreland began a study to evaluate the rela-
tions between ground water and surface water in the
Silver Creek area of Blaine County. A network of

114

about 75 wells has been selected for monthly water-
level monitoring to document ground-water fluctua-
tions. Much of the basic information on well con-
struction, use of water, owner’s name, and drillers’
logs has been collected for entry into the computer
file.

NEVA DA

Water-resource appraisal of Carson River basin

The Carson River basin study area encompasses
about 9,600 km2 in western Nevada. According to
P. A. Glancy and T. L. Katzer, estimated average an-
nual inflows to the area during the 1919—69 study
period are: (1) About 1,800 hm3 of precipitation, (2)
390 hm3 of Carson River flow from California, (3) 7
hm3 of Humboldt River tailwaste, and (4) 220 hm3
of water imported from the Truckee River drainage.
Estimates of major annual outflow budget com-
ponents include (1) an undetermined quantity of pre-
cipitation that evaporates, (2) about 370‘ hm3 of
shallow ground-water evapotranspiration and con-
sumptive crop use, and (3) about 310 hm3 of evapora-
tion from surface-water bodies. However, the com-
bined 1971 domestic, municipal, industrial, and live-
stock use was estimated at about 10 hma. Available
data suggest that, aside from riverflow, the Carson
Valley ground-water reservoir at the upstream end
of the area is the best available source of large quan-
tities of high-quality water. In contrast, Carson
Desert, at the terminus of the area, has a vast quan—
tity of ground water in storage, but it is believed to
be largely unacceptable for most uses. Intervening
hydrographic subbasins generally have significantly
large quantities of stored ground water of intermedi-
ate quality.

Effects of pumping on the water resources of Smith Valley

In 1972, inflow to Smith Valley in the West Walker
River basin was below normal, and thus the supply
of irrigation water available from the river was de-
creased. Supplemental water pumped from wells re-
sulted in the net mining of approximately 7.4 hm3 of
water from ground-water storage. According to F. E.
Rush and C. V. Schroer, the ground water will be
replenished by the large amount of infiltration of ir-
rigation water to the water table during years of
above-normal river flow.

 

GEOLOGICAL SURVEY RESEARCH 1975

OREGON

Ground water in the Columbia River Basalt Group on the

Umatilla Indian Reservation

J. B. Gonthier reported that a local poorly defined
zone of very low hydraulic conductivity occurs at
depths between 60 and 110 m in the Columbia River
Basalt Group aquifer on the Umatilla Indian Reser-
vation just east of Pendleton. Ground water in the
basalt above this zone is part of a shallow local flow
system that discharges to the Umatilla River in
winter and spring. Many wells tapping this shallow
system at lower elevations in the Umatilla River val-
ley, west of the Indian agency near Mission, flow
under low head during that period. However, wells
deeper than 110 m generally tap a regional flow sys-
tem that is defined by static water levels more than
60 m below the land surface.

Ground water leaks downward from the shallow
flow system to the deeper regional system through
uncased wells. This leakage probably is increasing
because the number of deep wells that penetrate both
systems is increasing. Local permanent water-level
declines in the shallow flow system could result, and
movement of waterborne contaminants through the
wells is also possible.

A local seasonal decline of ground-water levels re-
sults from the concentration of pumpage in a small
area (secs. 4, 5, and 7—10, T. 2 N., R. 33 E.). Pump-
age has gradually increased because of the growth of
the population and the use of ground water for irri-
gation. Local declines are suflicient to require deep-
ening of individual wells; as pumpage continues to
increase, the problem will become more extensive
areally.

Flow of the Warm Springs River

Studies on the Warm Springs Indian Reservation
by Antonius Laenen and J. H. Robison showed that
the Warm Springs River receives nearly all of its
base flow from highly permeable young volcanic
rocks in the Cascade Range. Little additional flow is
gained after the river emerges from the mountain
front onto the plateau formed on poorly permeable
Tertiary rocks. Seepage measurements during a
base-flow period showed that springs abruptly in-
creased discharge of the river from 0.14 m3/s to 1.9
m3/s in one reach of less than 0.5 km.

Base flow of Lincoln County streams

Measurements made by Antonius Laenen and F. J.
Frank ,showed that base flows are low for streams
. along the coast of Lincoln County. Variations in the

WATER~RE SOURCE INVESTIGATIONS

base flows and the yields of well-s are directly related
to local geology. The following table shows relative
base flows of streams in several geologic units deter-
mined from a series of measurements made during
September 1972:

Base flow
Geologic unit Aye (m3 5’1 km-2)
Tyee Formation (Sandstone) __middle Eocene 0.0005 to 0.002
Marine terrace deposits _______ Pliocene 0.0010 to 0.009
Siletz River Volcanics ________ early and middle
Eocene 0.0050 to 0.007
Sand dunes _________________ Quaternary 0.0060 to 0.016

During a higher base-flow period in August 1974,
flows were measured in the Yachats River basin in
southern Lincoln County. In that area, base flows
from Eocene marine siltstones and sandstones were
low (about 0.003 m3 s—1 km”). The highest‘base
flows, in streams along the contact between thema-
rine sediments and Eocene basalts, were about 0.008
m3 s—1 km—z. Base flows from the basalts were slight-
ly less, about 0.007 m3 s—1 km—z.

Diamond Lake inflow streams

Streams flowing into Diamond Lake show marked-
ly different flow characteristics that reflect differ-
ences in the geology of their drainage areas. An
evaluation by D. D. Harris of inflow to the lake for
the 1972 and 1973 water years showed that runoff
was exceptionally high in 1972 and very low in 1973.
Long-term records for nearby streams indicate that
runoff in 1972 was the second highest and in 1973
was the third lowest in more than 30 yr.

Silent Creek, the largest contributor to the lake,
flows into the southern end of the lake from the
water-retentive pumice-covered area on the slopes of
ancient Mount Mazama north of Crater Lake. The
mean flow of Silent Creek in the 1972 water year was
1.02 m3/s, with a maximum daily flow of 1.44 m3/s
and a minimum daily flow of 0.91 m3/s. In 1973, the
mean flow was 0.93 m3/s or 92 percent of the 1972
mean flow. The maximum daily flow in the 1973 wa-
ter year was 1.13 m3/s, and the minimum daily flow
was 0.82 m3/s. The .second largest contributing
stream is Short Creek, which also drains the pumice-
covered area to the south and had average discharges
of 0.40 m3/s and 0.34 m3/s in the 1972 and 1973 water
years, respectively. The 1973 flow was 86 percent of
the 1972 flow.

In contrast to the steadily flowing streams from
the pumice-covered areas, streams that drain the
area of less water retentive, older igneous rocks east
and west of the lake have large variations in flow.
The combined average discharge from these areas
was 0.22 m3/s in the 197 2 water year compared with

 

115

0.008 m3/s in 1973, only 4 percent of the 1972 flow.
Mean monthly flows during the 2 yr varied from 0.71
m3/s to no flow.

WASHINGTON

Seismic profile lines in the Spokane area

According to H. H. Tanaka, results of seismic ob-
servations along four profile lines in the Spokane and
Little Spokane River valleys indicate that the crys-
talline and metamorphic bedrock underlying the un-
consolidated gravel aquifer ranges in depth from less
than 90 m to more than 360 m. A north—south profile
line 3 km west of the Washington-Idaho border
shows a V-shaped valley with bedrock 390 m deep
about 1.6 km north of the Spokane River, between
secs. 2 and 3, T. 25 N., R. 35 E. A northeast-south-
west profile from the base of Five Mile Prairie across
the Spokane River indicates that bedrock is over 270
m deep 300 m east of the river in sec. 28, T. 26 N., R.
42 E. An east—west profile in the Hillyard area shows
bedrock about 240 m deep between seCs. 20 and 21,
T. 26 N., R. 43 E. A northeast-southwest profile line
in the Little Spokane River valley shows that bed-
rock is less than 90 m deep beneath the river in sec.

:3, T. 26 N., R. 42 E. Information from the seismic

survey will be used to analyze the quantitative
ground-water flow in the Spokane area.

SPECIAL WATER-RESOURCE PROGRAMS
SALINE WATER

Houston Ship Channel identified as source of saline water
entering the Chicot aquifer in the Houston, Texas, area
Large ground-water withdrawals from the Chicot

aquifer in the area of the Houston Ship Channel have

caused artesian water-level declines of as much as

107 m, and saline water is now leaking into the aqui-

fer from surface-water bodies. Results of water-

quality studies by D. G. Jorgensen indicated that the

Houston Ship Channel is the main source of saline

water entering the aquifer and that simple disper-

sion (water mixing) is the main chemical—transport
agent. A preliminary analysis of the data indicates
that, although the ship channel is a source of con-

tamination, saltwater intrusion has not yet caused a

significant deterioration of water quality in the

aquifer.

Freshwater-saltwater interface on Cape Cod, Massachusetts

M. H. Frimpter, J. H. Guswa, and C. J. Londquist
reported that two groups of observation wells were

116

drilled during the initial phases of a program de-
signed to locate and monitor the transition zone be-
tween freshwater and saltwater on Cape Cod.

In Wellfleet, wells were drilled in sand approxi-
mately 150 m from the high—tide line of Cape Cod
Bay at depths of 9, 14, 21, and 29 m. The chloride
concentrations in water samples collected from these
wells were 58, 93, 8,100, and 11,000 mg/l, respective-
ly, these values indicating that at this site the fresh-
water lens is about 15 m thick.

At Head of the Meadow in Truro, the wells were
drilled approximately 150 m from the high-tide line
of the Atlantic Ocean but less than 30 m from the
edge of a salt marsh. At depths of 5, 12, 19, and 27
m, the chloride concentrations in water samples were
8,600, 4,500, 240, and 2,300 mg/l, respectively. The
pattern of chloride concentration is evidence of the
existence of the edge of a freshwater lens that is
being recharged with brackish water from the tidal
marsh. Similar conditions were observed in shallow
wells, less than 2 m deep, in two tidal marshes.

Seawater intrusion in Dade County, Florida

Continuing studies of seawater intrusion by J. E.
Hull and D. J. McKenzie (1974) indicated landward
movement of the salt front during 1974 to within 1.4
km of the Miami-Dade well field in Miami Springs
and into the well field at Homestead Air Force Base.

Saltwater-freshwater mapping, West Virginia

Structure contour maps of the upper surface of
saline ground water in West Virginia show areas in
which saline water occurs at shallower than normal
depths. The “shallow” saline water occurs both nat-
urally and artificially through upward migration re-
sulting from man’s activities. In stream and river
valleys, saline water moves upward along faults or
fracture zones from the connate brines that are pres-
ent at depth. Oil and gas wells that were not properly
cased or that have been abandoned and not adequate-
ly plugged have provided avenues for upward move-
ment of saline water. Other occurrences of saline
water at shallow depths are associated with subsur—
face disposal of brines from oil separators and the
reduction in the freshwater head in valleys by the
dewatering of permeable zones under adjacent hills
where there are coal mines. J. B. Foster has been
checking geophysical well logs and brine well data in
an effort to differentiate areas of naturally occurring
“shallow” saline water from areas that have been
contaminated by industrial activities.

 

GEOLOGICAL SURVEY RESEARCH 1975

DATA COORDINATION, ACQUISITION,
AND STORAGE

OFFICE OF WATER-DATA COORDINATION

Water-data coordination activities continued dur-
ing the year with special emphasis on field coordina-
tion of data-acquisition activities, development of
recommended methods for water-data acquisition,
and preparation of hydrologic unit maps of the Na-
tion. Closely related activities included implementa-
tion of river-quality assessment activities and the
level I accounting network and further work on the
design of NAWDEX.

The ninth meeting of the Interagency Advisory
Committee on Water Data was held on October 22,
1974, in Res-ton. Members of the non-Federal Ad—
visory Committee on Water Data for Public Use were
invited to attend this meeting.

The “Summary of Plans for Acquisition of Water
Data by Federal Agencies, Fiscal Year 1976,” re-
leased in June 1975, contains a digest of plans for
water-data acquisition in each of the 21 regions
designated by the Water Resources Council (WRC)
and information on activities of national scope as
reported by officials at headquarters level. Activities
covered during this field coordination cycle included
specific plans on long-term stations for surface-water
stage, flow, and quality and for ground-water quality
and general information on other water-data needs.
The field coordination activity planned for fiscal year
1977 was initiated in May 1975 to cover the same
activities and to update the “Catalog of Information
on Water Data.” The 1974 edition of the catalog, pre-
pared in 21 separate volumes corresponding to the
water-data acquisition activities in the 21 regions,
reflected activities as of January 1, 1974, for those
stations being operated for a period of 3 yr or more.
The new edition will contain a cross-reference list to
tie the coding system (map number and letter used
on the catalog station-location maps) to the new
eight-digit hydrologic unit codes used on the State
Hydrologic Unit Maps. The new State Hydrologic
Unit Maps will replace the 1:1,000,000-sca1e station-
location maps previously published (latest edition,
1972) in conjunction with the catalog.

The new series of USGS base maps, “State Hydro-
logic Unit Maps,” prepared by the Office of Water
Data Coordination in cooperation with the WRC, re—
ceived the approval of the National Programs and
Assessments Committee of the WRC. The first 27 of
the 1:500,000-scale maps were published and are be-

WATER-RESOURCE

ing sold by the USGS. The remaining 26 maps are
expected to be published early in 1976.

The Coordinating Council for Water-Data Acquisi-
tion Methods, established in 1974 with A. 1. Johnson
as methods coordinator, held three meetings during
the year. Sixteen agencies are now represented on
the council, which met in October 197 4 and February
and June 1975 to plan and discuss participation of
the working groups involved in developing the hand-
book of “Recommended Methods for Water-Data Ac-
quisition,” advise the working groups on their recom-
mendations, and approve the outlines of the 10 chap-
ters submitted by the groups. Ten working groups
were established by the council to expand the hand-
book into 10 chapters covering (1) surface water,
‘(2) ground water, (3) sediment, (4) biologic and
bacteriologic quality of surface and ground water,
(5) chemical, inorganic and organic, and physical
quality of surface and ground water, (6) soil mois-
ture, (7) basin characteristics, (8) evaporation and
transpiration, (9) snow and ice, and (10) hydrome-
teorological observations. The groups held their ini-
tial meetings in Washington, DC, from January 13
to 24, 1975; 120 participants represented 21 Federal
agencies. The working groups met for 3 d of sessions
and elected chairmen and Vice-chairmen for their
respective groups, prepared preliminary chapter out-
lines, assigned various tasks to the members, and
prepared recommendations for action by the Coordi-
nating Council. Non-Federal involvement in the rec-
ommended-methods activity was initiated by organ-
izing the Ad Hoc Working Group on Recommended
Methods, made up of nine members from the Ad-
visory Committee on Water Data for Public Use.
This group held meetings in February and May 1975,
with the result that over 100 non-Federal experts
and agencies were asked to review the detailed chap-
ter outlines for the new handbook of “Recommended
Methods for Water Data Acquisition.”

The second 1-yr NAWDEX contract with Planning
Research Corporation was completed in May 1975
and included the following: (1) Definition of the for-
mat and contents of a Master Water-Data Index and
the procedures for its implementation, (2) develop-
ment of a memorandum of understanding for partici-
pants, (3) identification of sources of water-related
data, and (4) preparation of an operations manual
for the system. In addition to the completion of con—
tractual efl’orts, limited access to the data file of the
National Water Data Storage and Retrieval System
(WATSTORE) was made available to other Federal

 

agencies and major non-Federal cooperators as of

INVESTIGATIONS 117

June 1, 197 5. This access is initially restricted to the
Station Header File and the Daily Values File of the
WATSTORE system. A user’s manual containing a
detailed description of the WATSTORE files and
complete instructions for access to the files was also
developed and made available to all users of the
system.

WATER-DATA STORAGE SYSTEM

The USGS users a digital computer to process,
store, retrieve, and display water-resource data. The
computer is also used with water-resource studies
that require capabilities in statistical and analytical
techniques, graphical display and map presentation
of data, and mathematical modeling of hydrologic
systems. The computer system consists of a central
computer located in Reston, Va., and remote terminal
facilities located in 45 States.

Data on daily discharge, collected by the USGS
and cooperating Federal and State agencies at about
10,000 regular streamfiow stations, are stored on
magnetic tape. The volume of data holdings is'equiv-
alent to about 280,000 station years of record. More
than 78 percent of all streamflow data collected un-
der this program are covered. The data are stored
in discrete units containing figures for daily water
discharge for each gaging station and for each year
of record; thus, the data are compatible with a varie-
ty of statistical programs for analysis on the basis
of calendar years, water years, climatic years, or
any other desired period.

An automated system for storage and retrieval of
surface-water-quality data has been in use since
1959. All data collected since then, plus selected long-
term historical records, have been entered into the
system. The system contains the following types of
data: (1) Chemical and physical analyses of surface
water, (2) suspended sediment, (3) water tempera-
ture, (4) specific conductance, and (5) multi-item
data collected by digital monitors.

A new automated system for storage and retrieval
of ground-water data has been introduced. The
Ground-Water Site Inventory data base operates
under a proprietary data-base management system
that allows data retrieval on the basis of the values
of about 30 key parameters. Information in the new
file includes data on location, physical characteristics,
construction history, geohydrology, aquifer charac-
teristics, field quality determinations, water levels,
and water withdrawals for wells, springs, or other
sources of ground water. By the end of June 1975,
records of about 100,000 wells and springs had been

118

converted from the older punch—card format and en-
tered into the new system.

URBAN WATER PROGRAM

During.1975, the USGS continued its program of
hydrologic investigations in urban areas. A. F. Pen-
dleton, Jr., reported that 225 active projects were
directly related to urban water problems, and many
others were indirectly related to urban problems.
The 225 projects represent about 20 percent of the
total water-resouroe-investigation projects in prog-
ress during the year.

URBAN WATER-RESOURCE STUDIES
Alaska

. G. O. Balding reported that a project is underway
to develop ground-water resources in Mendenhall
Valley for the city and borough of Juneau. In order
to delineate the physical, chemical, and hydrologic
properties of the aquifer, a 61-m-deep test well is
being drilled in the glacial-o-utwash deposit-s in the
valley. Drilling is being done by cable-tool methods,
and cutting samples are being collected every 1.5 m
or less. The well has been drilled to a depth of 26 m
with 1.2 m of screen exposed between depths of 23.8
and 25.0 m in a zone of coarse sand and pea gravel.
Observation wells have been drilled at distances of 30
to 46 m from the test well. Chemical analyses indi-
cate a calcium bicarbonate type of water with low
dissolved-solids concentrations (less than 100 mg/l)
and dissolved-iron concentrations ranging from 40
to 1,100 ,ig/l.

According to C. E. Sloan, both surface and ground
water are locally abundant in the area between Cop-
per Center and Summit Lake. Surface-water flow ap-
proaches zero during the winter months in all
streams except major rivers such as the Tazlina and
the Gulkana. Turbidity affects water quality in glaci-
al lakes and streams during the high summer-flow
period. Color is high in sluggish streams, such as
Sourdough and Haggard Creeks, that drain exten-
sive muskeg or swampy areas. Most surface water is
of a dilute calcium bicarbonate type, low in dissolved
solids and usually clear. Summit and Paxson Lakes
also contain dilute calcium-bicarbonate-type water
that is very clear except in places near the major in-
flow areas, which temporarily increase in turbidity.
Both lakes are thermally stratified by late summer,
but they are near saturation with respect to DO
throughout the water column during the entire year.
Ground-water quality is poor in the central part of

 

GEOLOGICAL SURVEY RESEARCH 1975

the Copper River basin, particularly in the vicinity
of Glennallen, owing to high salinity and hardness.

L. L. Dearborn, Chester Zenone, and D. E. Don-
aldson reported significant results of their hydrologic
studies at Anchorage. According to Dearborn, rapid
residential growth in the Hillside area southeast of
metropolitan Anchorage may cause depletion of aqui-
fers and pollution of ground water as a result of
extensive development of small-lot tracts. Ground-
water yields are low and may even be inadequate for
single-family requirements in some parts of the area.
The low permeability of surficial glacial sediments
limits the efficient operation of septic-tank systems
in this unsewered residential area. Zenone concluded
that the cumulative effect of reclamation of muskeg
(swamp) terrain, installation of municipal sewers,
and residential and commercial development prac-
tices have altered hydrologic-budget factors and
caused declining water levels in Sand Lake, an urban
lake in the Anchorage area. Donaldson reported that
urban-area runoff into Sand Lake from melting snow
and ice in March 1974 contained the following con-
centrations of toxic metals: 20,000 ,ug/l of Fe, 600
Mg/l of Pb, and 40 ,ug/l of Cu. These concentrations
greatly exceed the background levels of those consti-
tuents in the lake itself.

Water-availability studies in the Anchorage area,
where a rapidly growing population is creating in-
creased water demands, continued under the direc-
tion of G. S. Anderson. Artificial-recharge experi-
ments have proved the feasibility of increasing po-
tentiometric. heads locally near production wells to
augment their yields. Analyses of aquifer test data
in the southern part of Anchorage indicate that a
production well there would be capable of yielding
3.8 to 5.7 million litres per day.

G. W. Freethey reported that water supplies
needed for expansion of fish-rearing facilities along
the lower reaches of Ship Creek can probably be
provided through the conjunctive use of water from
the stream itself and the underflow in the alluvium
adjacent to the stream channel.

Florida

An urban-hydrology study of the Tampa Bay re-
gion began in April 1974. Information collected as
part of the study will provide a current data base on
the quantity and quality of precipitation and stream-
flow for small urban watersheds under various types
of development. Data that are synthesized by the use
of urban watershed models will enhance planning and
management evaluations and facilitate decisions re-

WATER-RE SOURCE INVESTIGATIONS

garding proposed future development and water-
management alternatives.

G. E. Seaburn reported that current work activi-
ties include the planning and installation of data net-
works and the compilation of data describing water-
shed characteristics. Streamflow and rainfall instru-
ments have been installed in 10 basins. Studies are
underway to determine the feasibility of supplement-
ing rainfall data with available radar imagery and
to evaluate the use of automatic water-quality sam-
pling equipment and continuous water-quality moni-
tors to collect data on the chemical quality of rainfall
and runoff. If currently available equipment does not
prove reliable, samples will be hand collected at each
stream site during storm periods.

L. V. Causey, R. B. Stone, and M. I. Backer pre-
pared 18 maps (1124,000 scale) that show geohydro-
logic information needed for urban land-use plan-
ning for an area of about 780 km? in the southwest-
ern portion of Duval County. Recharge occurs in
about 60 percent of the area; the water table is with-
in 1.5 m of land surface in about 90 percent of the
area; the potentiometric surface of the Floridan
aquifer ranges-from less than 7.6 m to about 18 m
above sea level; land surface ranges from near sea
level to 31 m; and artesian wells will flow in about
35 percent of the area. Drainage maps show basin
divides, drainage areas, gaging sites, and the direc-
tion of surface runoff.

Maryla nd

W. F. White and E. G. Otton reported that con-
cern over adequate domestic ground-water supplies
and safe underground disposal of domestic sewage
efl‘luent in the Baltimore, Md., and Washington, D.C.,
areas has resulted in the preparation of a series of
environmental geohydrologic maps at a 124,000
scale. These maps, beginning with the White ~Marsh,
Md., 71/2-Inin quadrangle prepared by Otton (1974),
show areal geology, location of wells and springs,
depth to water table, availability of ground-water
supplies, and geohydrologic constraints on under-
ground sewage disposal. The maps should be useful
to local government agencies, engineers, planners,
and members of the general public who are con-
cerned about problems of water supply and sewage
disposal in urban areas without public utilities.

Minnesota

D. C. Larson, S. P. Larson, and R. F. Norvitch used
a variation of Darcy’s law to determine the relative
distribution of steady-state leakage downward to the
Prairie du Chien-Jordon aquifer, the major aquifer

 

119

in the Twin Cities metropolitan area. Available data
and estimates of vertical hydraulic conductivity for
geologic units indicate that major leakage to the
aquifer occurs in formation subcrop areas, especially
where these areas are overlain by the most perme-
able glacial drift. The relative distribution of addi-
tional leakage downward to the aquifer, resulting
from increased pumpage during the summer, was
also determined. Calculations indicate that 10 to 20
percent of the increased summer pumpage is derived
from increased leakage. The remainder is probably
from captured natural discharge and induced re-
charge from major streams within the influence of
summer cones of depression.

URBAN RUNOFF AND FLOODS
Kansas

A flood-insurance study for Wichita was recently
completed by D. B. Richards and C. O. Peek for the
Federal Insurance Administration of HUD. Results
of the study include (1) water—surface profiles of the
10-, 50-, 100-, and 500-yr floods, (2) water-surface
contours of the 100-yr flood, (3). flOOd-hazard factors,
and (4) the location of regulatory floodway bound-
aries (the 100-yr flood is the regulatory flood).

The index-flood method was selected for the study
to determine the flood-frequency discharges (Qm)
for ungaged stream sites and for varying degrees of
urbanization (as measured by the percentage of the
drainage area having an impervious surface) for the
city of Wichita. The index flood is the 2-yr flood
(Q2). The basic curve of this method is the ratio of
Qm/Q2 (for rural conditions) versus recurrence in-
tervals (RI). This curve was calculated after con-
sideration of (1) statewide flood-frequency analyses
and reports (including channel geometry), (2) ap-
plication of the RAREVENT computer program
(Carrigan, 1973), (3) analyses of flood-frequency
results from basins in central Kansas with 30 or
more years of homogeneous flood records, and (4)
other published flood—frequency results.

Regression analysis of the 2- and 100-yr floods pro-
duced the generalized relationships for Q2 and. Q10.)
discharges in cubic metres per second. The function-
al relationships betWeen the Qm and the contributing
drainage area (A) in square kilometres and the per-
centage of the basin drainage area covered by ‘im-
pervious surface (%I) are:

Q2=2.77 (A)0.60 (%I) 0.26
QIOO = 15-70 (A) 0'64 (701) 0'17
These results support conclusions from previous in-
vestigations, namely, that urbanization significantly

120

increases the magnitude of the 2-yr flood (two or
three times) but has less effect on high-magnitude
floods.

New Jersey

S. J. Stankowski (1974) developed a rapid and in-
expensive technique for estimating flood-peak mag-
nitudes having selected recurrence intervals ranging
from 2 to 100 yr for drainage basins in New Jersey
larger than 2.59 km2 with various degrees of exist-
ing or projected urban and suburban development.
Four parameters are required for use of the method.
Three of these—basin size, channel slope, and sur-
face storage within the basin—can be measured from
topographic maps. The fourth is an index of man-
made impervious cover that can be determined for
existing and future development conditions from
census data and population projections that are
readily available from regional, State, and local plan-
ning agencies. This index is based on correlations be-
tween population density and the proportions of land
area in each of six urban and suburban land-use
categories found in 567 New Jersey municipalities
with population densities ranging from less than 40
persons/km2 to over 15,000 persons/km? By weight-
ing the proportions of land use with average per-
centages of manmade impervious cover found in cor-
responding land-use categories, a relation was de—
veloped between population density and the propor-
tion of manmade impervious cover resulting from
different degrees of urban and suburban develop-
'ment. Mathematical relationships for estimating
peak discharges for selected recurrence intervals
were developed from thorough analyses of flood
peaks and watershed characteristics for 103 sites in
New Jersey. In the analyses, flood characteristics for
each site were determined from frequency analysis
of the annual flood-peak record and related by multi-
ple regression to the characteristics of the water-
shed. Urban and suburban development is shown to
increase flood peaks up to 3 times at the 2-yr recur-
rence interval and up to 1.8 times at the 100—yr recur-
rence interval as statewide averages.

New York

D. A. Aronson reported development of a mathe-
matical procedure for analyzing the operating char-
acteristics of storm-water basins on Long Island. By
using finite-difference equations, maximum storage
of storm runoff during theoretical high-intensity
storms was determined for the typical storm-water
basin in Nassau County. Analyses indicate that the
test basin would fill to only 30 percent of available

 

GEOLOGICAL SURVEY RESEARCH 1975

storage capacity during a storm having a recurrence
interval of 100 yr, given an observed infiltration rate
of 0.46 m/h. The apparently large safety factor in-
herent in this basin and similar basins on Long
Island is due primarily to the fact that contemporan-
eous exfiltration (leakage losses) during inflow of
runoff is not considered in basin-design criteria. The
large unused storage capacity of many storm-water
basins makes them well suited for the simultaneous
recharge of highly treated waste-water and storm
runoff, as long as infiltration rates at the basin walls
are not reduced appreciably and waste-water storage
is kept to a minimum.

Tennessee

According to H. C. Wibben, preliminary data indi-
cate that urbanization in metropolitan Nashville will
increase the magnitude of 2-yr—flood discharges
about 30 to 40 percent and the magnitude of 100-yr—
flood discharges less than 20 percent. Current de-
velopment practices include very few improvements
to the natural drainage systems; however, natural
channel conveyance is quite good. Soils in Davidson
County are thin and relatively impermeable, and rock
outcrops are prevalent throughout most of the coun-
ty. Consequently, the effects of urbanization upon
flood discharges are less pronounced in Davidson
County than those indicated by previous studies in
other parts of the country.

QUALITY OF STORM RUNOFF IN URBAN AREAS

Florida

C. B. Sherwood, Jr., and H. C. Mattraw, Jr., re-
ported that an automatic storm-data collection sys-
tem is being used to collect rainfall, flow, and water-
quality samples in a small residential area north of
Fort Lauderdale. The study location is a moderate-
density single-family residential neighborhood with
swale drainage. Season, antecedent dry condition,
and rainfall influence magnitudes of most water-
quality parameters. Total coliform bacteria counts as
high as 2 million colonies per 100 ml indicate that
storm-water runoff is a major source of surface-
water contamination.

HYDROLOGIC EFFECTS OF WASTE DISPOSAL
IN URBAN AREAS

Alaska

Water-quality and lithologic data from test Wells
drilled in the city of Anchorage landfill indicate that
it is highly unlikely that two nearby municipal wells
will be polluted by leachate from the landfill, accord-

WATER-RESOURCE INVESTIGATIONS

ing to L. L. Dearborn and D. E. Donaldson. Solid-
waste disposal in this high-water-table area has
caused serious localized pollution of shallow (0.6 m)
unconfined ground water, but municipal—supply aqui-
fers between depths of 55 and 100 m are confined
beneath and protected from landfill pollutants by
thick, poorly permeable clay-silt deposits.

Florida

H. J. McCoy and C. B. Sherwood, Jr., reported that
shallow wells (Biscayne aquifer) were sampled in
the vicinity of a proposed deep-injection well in Fort
Lauderdale. A core hole was drilled to obtain detailed
lithologic data on the aquifer to a depth of 61 m.
Three salinity test wells were drilled to more ac-
curately delineate the position of the saltwater front
at depth in the Biscayne aquifer. Geohydrologic data
on the deep Floridan aquifer were compiled and pro-
vided to the cooperator, the city of Fort Lauderdale,
for use in preparation of injection-well plans.

The city of West Palm Beach, with financial assist—
ance from EPA, is constructing a new secondary
sewage-treatment plant to handle the increasing
amounts of domestic waste water. EPA personnel
have advocated disposal of the effluent by deep-well
injection. F. W. Meyer and W. A. J. Pitt, Jr., as part
of a cooperative program with the city, collected
data from a 1,07 Q-m-deep test well, presently under
construction, to evaluate the capability of a saline,
deep artesian aquifer to accept treated effluent.

Quarterly sampling of test wells located in and
around the NW. 58th Landfill, Dvade County, con-
tinued. Downgradient movement of a wide variety
of landfill leachates has been established. J. E. Hull
reported that most parameters of environmental con-
cern have decreased to near-background concentra-
tions within several hundred metres of the original
deposition site.

New York

Results of a study of declining water levels in an
83-km2 sewered area in Nassau County by M. S. Gar-
ber and D. J. Sulam showed that ground-water levels
in the area have declined an average of 3.6 m relative
to a nearby unsewered area to the east. Although
sewering did not begin until 1953, water-level fluctua-
tions were analyzed by the double-mass—curve tech-
nique for the period 1938—72 in order to establish a
correlation between sewered and unsewered areas.
Pumpage effect was evaluated with a five—layer ana-
log model of the Long Island ground-water reservoir.
Pumpage in adjacent Queens County accounted for
1.5 m of the 3.6-m decline. The remaining 2.1 m of

 

121

decline is attributed to sewering. Streamflow in the
study area has also declined as a result of lowered
ground-water levels. Total storage in the ground-
water system for the period 1953—7 2 is estimated to
be 1.3x 103 m“.

WATER USE

Effects of 1974 oil embargo on water use for electric-utility
energy production

The USGS has published estimates of water use in
the United States every fifth year since 1950 (C. R.
Murray and E. B. Reeves, 1972). Interim estimates
of water used in 1974 for thermoelectric-energy pro-
duction (the largest withdrawal use) and hydroelec-
tric-power production (a nonwithdrawal use) were
made from the US. Federal Power Commission’s
(1975) preliminary data for 197 4 power production.

Murray noted from the data that, although total
electric-utility production in 1974 was about 1.865X
1012 kWh (an increase of 0.5' percent over 1973),
power output by fuel-burning plants declined to
about 1.565><1012 kWh (1.3 percent less than 1973).
An estimated 189 km“ of water was used for thermo-
electric-power production in 1973 (Murray, 1974).
The 1973 estimate should also be representative for
1974; a 1.3-percent decrease is well within the proba-
ble range of error of the water-use estimate. In con-
trast, water use for thermoelectric-power production
was 33 percent greater in 1970 than in 1965. There-
fore, it appears that the 1973—74 oil embargo did
strongly affect thermoelectric-power production and
water withdrawals.

Nuclear fuel was used for about 7.2 percent of the
thermoelectric power produced in 1974, a 35-percent
increase over 1973. Nuclear powerplants use slightly
larger amounts of water for power production than
coal-, oil-, or gas-fueled plants. The increased nuclear-
fuel use and its attendant larger water use can be
ascribed in part to the oil embargo.

On the other hand, hydroelectric-power production
in 1974, which was about 16 percent of total electric-
utility power production, increased 10.5 percent over
1973. The quantity of water used in producing the
approximately 0.300>< 1012 kWh of hydroelectric pow-
er was estimated to be about 4,600 km3. Repetitive
use of this water is evident—the amount used far
exceeds the total annual runoff of about 1,650 km3 in
the conterminous United States.

Use of water for rice irrigation increases in the Grand Prairie
area in Arkansas

H. N. Halberg reported that the amount of water
used for rice irrigation in the Grand Prairie region

122

in Arkansas in 1974 averaged 665.5 mm and that the
median value was 632.5 mm, although precipitation
during the 1974 growing season was greater than
normal. These values exceed the average of 558.8
mm and the median of 553.7 mm determined for
1928, 1929, and the period 1937—40 (Kyle Engler,
D. G. Thompson, and R. G. Kazmann, 1945). In the
are-a between. Bayou Meto and the Arkansas River,
the amount of water used for rice irrigation averaged
952.5 mm, and the median value was 858.5 mm in
1974.

Water supply and demand in the Minneapolis-St. Paul
metropolitan area

R. F. Norvitch reported that per capita use of both
surface water and ground water in the Minneapolis-
St; Paul, Minn., metropolitan area increased from
2401/d in 1900 to 680 l/d in 1970. Total surface-water
use in 1970 (exclusive of thermoelectric-power use)
was 5.81 mR/s, whereas total ground-water use was
8.98 m“/s. Future demand on both water sources by
the year 2000 is estimated at 26.2 m3/s, or about 760
l/d per person.

Total average streamflow, gaged near Where the
three major streams enter the metropolitan area, is
about 232 m“/s; however, during times of extremely
low flow, there is not enough water available to fully
satisfy all demands. About 43.8 m3/s of ground water
can be obtained by increasing pumpage in both the
Prairie de Chien-Jordan and the Mount Simon-Hinck-
Iey aquifers. This water would partially compensate
for surface-water shortages during extended low-
flow periods.

Use of water from public supplies in southwestern Pennsylvania

The jurisdictional and developmental complexities
of providing water service to municipal areas are
graphically illustrated in a 1:125,000—sca1e map by
R. M. Beall (1974) . The map shows areas serviced by
water-supply agencies within the 11,650-km2 six-
county greater Pittsburgh region in southwestern
Pennsylvania. Selected data for the 153 systems
mapped show that more than half serve fewer than
1,000 residential customers; only 11 systems serve
more than 10,000 residential customers. Residential
water use within the 11 largest systems accounts for
37 percent of the water used; the remainder is dis-
tributed among commercial, industrial, and other
customers and bulk sales and systems losses. Data
collected during the study show that the proportion
of .water used by the several classes of customers
varies widely among systems. The total estimated
average water use in 1973 by all listed systems was

 

GEOLOGICAL SURVEY RESEARCH 1975

about 1,400,000 m3/d. Privately supplied domestic,
commercial, industrial, and institutional systems,
which used water at perhaps 10 times the rate of
public systems, were not included in the assessment.

COORDINATE WATER-QUALITY PROGRAMS

Significant advances have been made in the imple-
mentation of the National Stream Quality Account-
ing Network (NASQAN), part of the level I ac-
counting element of the National Water Data Net-
work. J. F. Ficke reported that, during the 1975
fiscal year, 245 stations were added to NASQAN,
this addition bringing the network to a total of 345
stations, 66 percent of the ultimate design size of
525 stations. T. D. Steele, E. J. Gilroy, and R. O.
Hawkinson (1974) analyzed temperature and chem-
ical-quality data from 88 NASQAN stations and
detected significant long-term changes in tempera-
ture at 15 of 80 stations and significant changes in
dissolved-solids content at 15 of 88 stations. Accord-
ing to R. J. Pickering, NASQAN is designed to
report annually on the quality of the Nation’s sur-
face water and to give an accounting of water disp
charge and loads of selected constituents for each of
the 330 river-basin accounting units. Stations are
now operating in each of the accounting units. De-
tails of NASQAN design are described in a report
by Ficke and Hawkinson (197 5).

During fiscal year 1975, the National Pesticide
Water Monitoring Program, a subnetwork of NAS-
QAN operated cooperatively by the USGS and EPA,
was fully implemented to include quarterly sampling
of water and bottom sediment at 153 NASQAN sta-
tions by district personnel of the USGS Water Re-
sources Division. Each sample was analyzed for
about 20 different pesticide compounds by Han Tai
and his staff at EPA’s pesticide laboratory at Bay
St. Louis, Miss.

Since 1967, the USGS has operated a Hydrologic
Bench—Mark Network designed to provide continu-
ing uniform data on streamflow and water quality
in more than 50 small stream basins that are ex-
pected to remain in their present natural condition.
In a study of water-quality data for bench-mark sta-
tions, J. E. Biesecker and D. K. Leifeste (1975)
reported that, although natural water quality gen-
erally is very good, a sample from Bear Den Creek
near Mandaree, N. Dak., contained 3,420 mg/l dis-
solved solids. This high concentration in the “nat-
ural”,environment illustrates the difi‘iculty of dis-
tinguishing between manmade pollution and natural
water quality and indicates that natural processes

WATER—RESOURCE INVESTIGATIONS

can be principal agents in modifying the environ-
ment. Biesecker and Leifeste also observed Wide-
spread but very low-level occurrence of pesticide
residues in the natural environment. On the other
hand, of 642 analyses for minor metals, about 65
percent were below the level of detectability. The
dissolved-solids content and the relative abundance
of the major chemical constituents clearly reflected
the type of rock underlying the stream basin.

As part of a continuing activity to provide statis-
tical techniques for data analyses and evaluation of
water-quality networks, T. D. Steele (1974) further
developed and documented a harmonic—analysis tech-
nique for depicting the seasonal variability of stream
temperatures; his computer program contains op-
tions for assessing the effects of reduced sampling
schedules on annual stream-temperature depiction
and for analyzing the serial dependenceof continu-
ous records and harmonic residuals. T. D. Steele and
T. R. Dyar (1974) reported on the application of
this technique to temperature data for streams in
Georgia. Nonparametric tests were used by S. P.
Larson, W. B. Mann IV, and T. D. Steele (USGS)
and R. H. Susag (Twin Cities Metropolitan Sewer
Board) ( 1974) to statistically determine significant
long-term trends and make various graphic depic-
tions of water-quality records for the Minneapolis-
St. Paul, Minn., metropolitan area. Steele has also
demonstrated the utility of a bivariate-regression
model for taking advantage of correlated inorganic
chemical-quality variables by using several foreign
data sets.

The intensive river-quality assessment of the
Willamette River basin in Oregon continued with the
assistance of the ad hoc Working Group on River
Quality Assessment of the USGS Advisory Com-
mittee on Water Data for Public Use; the field work
for the Willamette River study was completed dur-
ing the year. River quality in two additional river
basins—the Chattahoochee River basin in‘Georgia
and Alabama and the Yampa River basin in Colorado
and Wyoming—is being intensively studied.

In 1975, the Central Laboratory System (com-
posed of the Doraville, Ga., Salt Lake City, Utah,
Albany, N.Y., and Denver, Colo., facilities) analyzed
some 100,000 water-quality samples. About 1.2 mil-
lion individual tests were performed, an increase of
50 percent over the number performed in 1974. The
increase in sample analyses resulted from new en-
ergy studies and from other expanded district and
Federal program activities. Federal programs pro-

duce about 15 percent of the total sample load for _

the Laboratory System, and district needs contribute

 

123

85 percent. The Central Laboratory System has the
analytical capability to routinely perform about 400
different tests on water, sediments, and biota.

INTERNATIONAL HYDROLOGICAL DECADE,
1965—1974

The 10-yr program of cooperative international
studies in scientific hydrology, known as the Inter-
national Hydrological Decade (IHD), drew to a
close on December 31, 1974. However, the United
States, together with many of the approximately 100
other countries participating in the IHD program,
will continue its studies as part of the International
Hydrological Program (IHP), which will be spon-
sored by UNESCO.

Following a recommendation of the Panel on Post-
Decade Procedures of the US. National Committee
for the IHD, the USGS.~was given the responsibility
for the guidance and operational direction of the
IHP. A secretariat for US IHP activities will be
established in the Office of International Activities
of the Water Resources Division at the USGS Na-
tional Center in Reston, Va.

During the year, USGS scientists continued their
participation in the IHD program. The network of
82 river stations that observe and record streamflow,
chemical quality, and suspended-sediment load was
maintained. This network provides a general index
of the discharge of surface water and of the dis-
charge of dissolved and suspended material from the
continent to the oceans. Collection of hydrologic data
also was continued at 23 lake and reservoir stations
and at 34 selected observation wells; these stations
provided information on water-level fluctuations and
on the chemical quality of lake, reservoir, and ground
water.

Hydrologic bench. marks established early in the
decade provide continuing information at 46 locali-
ties throughout the country on natural hydrologic
conditions largely removed from man’s activities.
Measurements of the tritium content of water in the
20 principal rivers in the United States and of the
tritium in precipitation at 16 localities are being
used to evaluate the efi’ect-s of precipitation on the
chemical character of inland waters.

Observations at all of these stations will be con-
tinued as part of the United States effort in the IHP.

During the year, USGS hydrologists participated
in international meetings of working groups, inter-
country exchange of experts, discussions of selected
activities chosen for particular years, and hydrologic
research at selected areas in the United States where

124

the results are expected to have international inter-
est or application.

I. J. Winograd participated in the International
Symposium on the Hydrology of Volcanic Rocks,
March 4—8, 1974, on Lanzarote, Canary Islands,
sponsored by UNESCO, the United Nations Develop-
ment Program, and the Spanish Government.

E. L. Hendricks served as one of the vice-chairmen
at the ninth and final session of the Coordinating
Council for the IHD at UNESCO House in Paris,
August 29—30, 1974.

Hendricks also was Chief of the US. delegation
to the End-of-Decade Conference on the Results of
the IHD and on Future Programs in Hydrology, also
held at UNESCO House from September 2—14, 1974.
R. L. Nace (1974) and J. S. Cragwall, Jr., partici—
pated in the conference as members of the US. dele-
gation.

During the conference, the Tercentenary of Scien-
tific Hydrology was celebrated September 9—12,
1974. Nace presented a report, “General Evolution
of the Concept of the Hydrological Cycle.”

During the End-of-Decade Conference, two sym-
posia were sponsored by the International Associa-
tion of Hydrological Sciences (IAHS). H. P. Guy,
R. F. Hadley, and R. H. Meade, J r., presented reports
at the Symposium on Effects of Man on Erosion and
Sedimentation, and H. H. Barnes, Jr., and G. F.
Smoot presented reports at the Symposium on Flash
Floods. Barnes also served as a reporter at the ses-
sions.

Nace continued his IHD activities as a member of
the Working Group on Water Balances. During the
year, he contributed some minor revisions and addi-
tions to the compendium report on the world water
balance.

R. E. Oltman and A. 1. Johnson participated in
the IAHS Bureau meeting held in Paris during the
End-of—Decade Conference. Johnson acted as US.
coordinator for the Tercentenary of Scientific Hy-
drology and its symposia.

 

GEOLOGICAL SURVEY RESEARCH 1975

R. L. Cory continued water-quality monitoring
and studies of the epifauna in the South, Rhode, and
West Rivers, small estuarine tributaries on the west-
ern side of Chesapeake Bay in Anne Arundel County,
Md. E. J. Pluhowski continued related studies on
radiation balances in the same estuaries.

G. H. Davis served as Chairman of the UNESCO
IHD Working Group on Ground-Water Studies until
the IHD ended in December 1974. Davis was also a
member of the Working Group on the Application
of Nuclear Techniques in Hydrology and served with
W. S. Keys and F. J. Pearson, Jr., of the US. Na-
tional Committee for the IHD.

G. C. Taylor, J r., was appointed to the IHP Panel

. of Editors for the “Guidebook on Ground-Water

Studies.”

The two IHD programs on snow and ice continued
under the direction of M. F. Meier until the end of
the IHD. Reports on the ice and water balances of
Gulkana, Wolverine, South Cascade, and Maclure
Glaciers for the 1967 water year were prepared, and
a streamlined program for the publication of data
for subsequent years was designed by R. M. Krim-
meI, L. R. Mayo, and W. V. Tangborn. An inventory
of the multitude of small glaciers and tiny masses
of perennial ice in California is being completed by
Austin Post (USGS) and W. H. Raub (San Jose
State College).

G. L. Faulkner participated in the bilateral US.-
Yugoslavia Seminar on Karst Hydrology and Water
Resources, held in Dubrovnik, Yugoslavia, June 2—7,
1975, and presented a report titled “Flow Analysis
of Karst Systems with Well-Developed Underground
Circulation.”

R. F. Hadley, chairman of the US. National Com-
mittee for the IHD Work Group on Representative
and Experimental Basins, assisted in the preparation
of a final report of the group’s activities; he sum-
marized accomplishments of the small-basin hydrol-
ogy programs in the United States during the IHD.

MARINE GEOLOGY AND COASTAL HYDROLOGY INVESTIGATIONS

MARINE AND COASTAL GEOLOGY

The continental margins are an important poten-
tial source of the fuel and raw mineral resources
required by our growing and increasingly urbanized
population. Knowledge of the geology, mineral re-
sources, geologic processes, and environmental rela-
tionships of the coastal zones, the adjacent shelves,
and the deep ocean is urgently needed to solve the
problems generated by the increased and often com-
petitive demands placed on the resources of these
regions.

The USGS is continuing its diversified geologic
investigations in the marine environment surround-
ing the Nation. Studies are being conducted in the
Atlantic, Gulf of Mexico, Pacific, and Alaskan con-
tinental margins and in the Caribbean Sea. Partici-
pation in the International Decade for Ocean Ex-
ploration and the DSDP has extended these studies
to the deep ocean as well. Many of the investigations
involve cooperative arrangements with other Fed-
eral agencies, State governmental agencies, univer-
sities, oceanographic institutions, and international
organizations. Results of the past year’s research
programs in marine and coastal geology are sum-
marized below.

ATLANTIC CONTINENTAL MARGIN

SHELF GEOPHYSICAL, STRUCTURAL, AND RESOURCE
STUDIES

In the past 3 yr, J. C. Behrecndt and J. S. Schlee
obtained multichannel (24 and 48) common-depth-
point seismic profiles from the coast to a 4500-m
water depth between Georges Bank and Florida. The
surveys show a thick section of presumed Mesozoic
to Cenozoic sedimentary rock beneath Georges Bank
andthe Baltimore Canyon Trough ofl’ Delaware and
New Jersey; this rock has seismic velocities of 5
km/s in its lower part. These velocities, typical of
carbonates, were interpreted in previous seismic
refraction studies as being those of crystalline base-
ment rocks. The new seismic data do not support the
existence of the basement ridge postulated to exist

 

beneath the Outer Continental Shelf off Maryland
but do correlate with a platform 6 km beneath the
outer shelf off New Jersey. The platform is inferred
to be an Upper Jurassic or Lower Cretaceous car-
bonate horizon or reef, and weak reflectors are ob-
served beneath it. Along the outer shelf off Georges
Bank, the seismic data suggest an irregular ridge at
a depth of 3 km that may be associated with the
intersection of a fracture zone (New England sea-
mounts) and the continental margin.

Profiles across Georges Bank east of New England
show up to 8 km of sediments of probable Mesozoic
and Cenozoic age in the ridgeabounded basin. Sea-
ward of the ridge, beneath the lower continental
slope and rise, about 4 to 5 km of sediment of pre-
sumably the same age overlie oceanic basement. The
northeasterly trending Baltimore Canyon Trough
thickens to over 12 km seaward of New Jersey, Dela-
ware, and Maryland but is broadly warped by an
igneous intrusion to the north. Off Maryland, the
sedimentary accumulation is a wedge that thickens
in a seaward direction and appears to be faulted
beneath the continental slope; this section of the rise
and lower slope is thicker (6 to 7 km) than that off
New England. The sedimentary wedge and trough
north of Cape Hatteras are interpreted to have
formed after rifting of North America and Africa.

SHELF ENVIRONMENTAL STUDIES

H. J. Knebel estimated the within-station variance
to show which of 31 variables are likely to be effec-
tive indicators of textural differences within the
Baltimore Canyon Trough area on the Atlantic Con-
tinental Shelf. The variables that are most diagnos-
tic of differences between stations are the percent:
ages of gravel and sand, median and mean phi sizes,
skewness, kuttosis, and percentages of coarse, medi-
um, and fine sand. Some of the 1Alpphi-sized fractions
within the sand range cannot define areal trends
effectively. The textural variability within the Balti-
more Canyon Trough area reflects the reworked and
sorted sediments that cover this part of the shelf and
that differ from the more gradational sediments that

125

126

overlie areas like the Continental Shelf off Washing-
ton State. The magnitude of the withinastation vari-
ance is not only important geologically, but it also
has environmental and legal ramifications for any
study that characterizes shelf areas with economic
potential.

GULF OF MEXICO AND CARIBBEAN
CONTINENTAL MARGIN

GEOPHYSICAL, STRUCTURAL, AND RESOURCE STUDIES
Salt structures and petroleum migration in the Gulf of Mexico

R. G. Martin, J r., studying the continental margin
of the northern and western Gulf of Mexico, found
it composed of thick transgressive and regressive sec-
tions of Tertiary and Quaternary classic sediments
deposited in offlapping wedges over mainly carbon-
ates of Cretaceous age. Large volumes of salt be-
neath these deposits have played an important role
in the morphological development of the gulf basin.
In the northern gulf, salt masses and shale ridges
have pierced and uplifted the sedimentary prism
from DeSoto Canyon‘to northern Mexico and from
the coastal plain to the foot of the continental slope.
These diapirs end abruptly along the Sigsbee and
Rio Grande Escarpments.

Salt domes beneath the northern gulf margin can
be grouped into morphological belts. Deep-seated
salt chimneys dot the inner shelf and adjacent
coastal plain, broad isolated salt stocks characterize
the middle shelf region, and broad semicontinuous
diapiric uplifts associated with shale masses domi-
nate the outer shelf and upper slope. Virtually the
entire continental slope from the Mississippi fan to
northeastern Mexico is underlain by massive salt
structures that interconnect at relatively shallow
subbottom depths. Salt structures on the middle slope
appear as very broad flat-topped steep-flanked mas-
sifs; structures under the lower slope are large
pillowlike swells between broad sedimentary basins
in shallow depressions in the salt mass.

The grouping of salt structures by relief, size, and
shape in the northern gulf region defines belts of
decreasing diapiric maturity fro-m the coastal plain
to the foot of the continental slope. The least mature
features in the cycle of salt tectonism in the northern
gulf are the Sigsbee Escarpment south of Texas and
Louisiana and the Rio Grande Escarpment to the
west. They represent the fronts of an advancing salt
“wave” that is responding to the load of sediments
accumulated in the gulf coast geosyncline.

C. W. Holmes analyzed samples from 330-m drill
holes on the Outer Continental Shelf and upper con-

 

GEOLOGICAL SURVEY RESEARCH 1975

tinental slope of the Gulf of Mexico. Sediments from
these features show significant mineralogical and
chemical variations, although the similarity of sedi-
ment types suggests constant sedimentation at least
since Pliocene time. In the sediments over the salt
intrusions on the outer shelf, t e abundance of ex-
panded clays (17 A) com-pare with that of the
nonexpanded material (10 A) decreases with depth.
Correspondingly, the cation exchange capacity and
total organic content decrease with depth. These
trends were not detected in the sediments away from
salt structures. The chemistry of the “pore water”
and trace metals adsorbed on the clay material re-
veals that a diffusion gradient has become estab-
lished. The driving forces appear to be heat diffu-
sion from the salt masses plus the migration of the
extracted water from the collapsing clay minerals.
These reactions have significant effects on the trace-
metal content and the anthropogenic mineral compo-
sition of the sediments; they also appear to be im-
portant in hydrocarbon migration.

Caribbean tectonic map

Compilation of a preliminary geologic-tectonic
map of the Caribbean region was nearly completed
during 1974 by J. E. Case. Analysis of the combined
onshore-offshore data provides a generalized chron-
ology for many of the younger deformed belts of the
region. Neogene to Holocene fold belts extend (1)
from the southern margin of the eastern Cayman
Trench through Hispaniola and along the southern
borderland of Puerto Rico to Anegada Passage; (2)
along the Venezuelan-Colombian borderland into the
Sinu-Atlantico basin of Colombia; (3) along the
northern Panama borderland into the Limon basin
of Costa Rica and Panama; and (4) east of the
Lesser Antillean are from Anegada Passage to the
delta of the Rio Orinoco. “Laramide” folds of the
Yucatan Peninsula and northern Guatemala extend
offshore along the Yucatan borderland to northern
Cuba and probably eastward to the Virgin Islands.
“Laramide” deformation of northern South America
can be traced eastward to at least Tobago and prob- '
ably to Barbados. For the most part, the interior
Yucatan, Colombian, and Venezuelan basins have
been tectonically stable during Neogene to Holocene
time.

Modern uplift of Antillean arc

The most recent tectonic movement on the north-
ern Antillean island arc appears to be a differential
axial uplift, at least in the Mona Passage area, be-
tween Puerto Rico and the Dominican Republic. The

MARINE GEOLOGY AND COASTAL HYDROLOGY INVESTIGATIONS

Isla de Mona lies in the middle of the passage but
south of the east-striking tectonic axis. A modern
sea-level nip is strongly developed on all the lime-
stone clifl‘s of the island, as well as on its neighbor
Monito, and small remnants of a fossil-elevated nip
are preserved‘in the cliffs at scattered localities.
Careful measurement of the height of the fossil nip
by J. V. A. Trumbull (USGS) and R. W. Rodriquez
(Puerto Rico Department of Natural Resources)
demonstrates an upward tilt toward the north of the
island during the unknown but clearly short time
between the formation of the two nips. The tilt
gradient at the island is 0.4 m/km, and linear pro-
jection north to the tectonic axis gives an uplift
there of 24 m. N 0 time base with which to measure
the tilt rate has been established. However, most
talus blocks show a fully developed modern nip;
hence, formation of the nip must be rapid. The rate
of cliff spalling is unknown.

COASTAL ENVIRONMENTAL STUDIES
Submarine valleys off Puerto Rico

Numerous uniformly developed submarine valleys
indent most of the insular slope along the northern
coast of Puerto Rico. J. V. A. Trumbull and Jose
Muniz (USGS) and R. W. Rodriguez (Puerto Rico
Department of Natural Resources) found that each
present-day river mouth on the northern coast has a
corresponding submarine valley but that there are
many more submarine valleys than river mouths.
These “extra” submarine valleys are located off
known or highly plausible former locations of river
mouths and may be a direct guide to previously un-
known locations of former river mouths. This new
information, when fully studied, will contributeto
the knowledge of the geomorphic history of Puerto
Rico.

Mercury in Matagorda Bay, Texas

C. W. Holmes found that the mercury content in
the sediments of the Matagorda Bay system was
anomously high in certain regions. These mercury-
rich sediments accumulated because of tidal currents
in the major channels of the bay and the general
sedimentological regime of the bay. In this system,
the tidal currents remobilized the mercury through
a combination of biochemical and physical factors
and thus reintroduced the mercury into the estuarine
circulation in a region where the turbidity maximum
was most prevalent. As a result, the mercury-rich
sediments accumulated in the upper reaches of the
bay.

 

127

PACIFIC CONTINENTAL MARGIN

Geophysical computer-processing equipment

D. H. Tompkins was engaged in designing a
marine-integrated data acquisition and processing
system (MIDAP) to be used in exploring the geol-
ogy and geophysics of the Outer Continental Shelf
and adjoining deep-sea areas off the Western United
States. The system will be located aboard the USGS
RV Samuel P. Lee and will construct the geologic
structure of these offshore regions from measure-
ments of the Earth’s magnetic and gravitational
fields, deep-penetration multichannel seismic reflec-
tion profiles, bathymetry, and high-resolution pro—
files of the upper hundred metres of sea floor.

Since the MIDAP system will provide real-time
processing of these data types,‘ on-board scientific
personnel will be able to interact With the processing
and receive graphical representations of processed
data as required. MIDAP is intended to provide the
scientist increased field flexibility by producing a
controlled real-time look at his data While the ship
is underway.

GEOPHYSICAL, STRUCTURAL, AND RESOURCE STUDIES

Southern California borderland

0n the basis of recent geophysical and sampling
cruises in the California continental borderland,
J. G. Vedder, J. C. Taylor, and G. W. Moore compiled
new maps that show the distribution of rocks by age.
Of particular interest are the pre-Miocene rocks,
Which include basement rocks of probable pre—middle
Cretaceous age and marine strata that have been
paleontologic‘ally dated by R. E. Arnal and J. D.
Bukry as middle Cretaceous, Late Cretaceous,
Eocene, and Oligocene. The basement rocks consist
of diverse types that show no detectable regional
zonation and include zeolite-bearing wacke and
argillite, blueschist, greenschist, amphibolite, pyrox-
enite, serpentinite, and saussuritized gabbro. Strata
older than early Miocene have not been found in
depositional contact on exposed basement ridges.

Miocene strata in the region south of the northern
island group seem to be limited to the Santa Rosa-
Cortes Ridge and the San Nicolas and Santa Cruz
basins, where subsurface interpretations on sparker
records have been made by Arne J unger and H. C.
Wagner. Upper Albian to lower Turonian claystone
has been cored from the unnamed ridge that forms
the southwestern. flank of Tanner basin, and Upper
Cretaceous siltstone is present on the knoll 25 km
west of San Nicolas Island. Eocene strata probably

128

are confined to the area encompassed by the Santa
Rosa-Cortes Ridge and the Santai Cruz-San Nicolas
basin systems. Marine claystone of Oligocene age is
present at Cortes and Tanner Banks and directly
south of Santa Rosa Island, but correlative non-
marine beds, which are widespread on the mainland,
have not been found in the borderland.
Paleogeographic reconstructions of Paleogene
strata by D. G. Howell suggested large—scale post-
Eocene lateral dislocations in the borderland and
adjacent areas. However, the apparent lack of re-
gional zonation in the metamorphic rocks precludes
interpretive restoration of the basement terranes to
their pre—Tertiary positions until more work is done.

Central California

The large shelf basins off the central California
coast, including the Santa Maria, Santa Cruz, Outer
Santa Cruz, Bodega, and Point Arena basins, orig-
inated in the late middle Miocene, according to oil-
company drilling results reported by Hoskins and
Griffiths (1971). E. A. Silver determined that this
timing coincides with a change in the direction of
motion between the Pacific and American plates
from about N. 22° W. earlier than 10 my. to N. 38°
W. between 10 and 5 my and N. 37° W. later than
5 my. These changes predict extensional movement
across earlier, more northerly trending boundary
faults; seismic reflection studies show that faults
along the edge of major basins have this same trend.
The reported synchroneity in the ages of formation
of these shelf basins is explained more easily by a
regional tectonic event related to changing plate mo-
tions than by local events or time-progressive tec-
tonics such as migrating triple junctions.

H. G. Greene and J. C. Ingle, Jr., found that ben-
thic foraminiferal assemblages of rocks dredged
from Monterey Bay represent greater depths than
their present occurrence; this discovery suggests a
late Pliocene-early Pleistocene uplift within the cen-
ter of the bay. Pleistocene megainvertebrate and
microinvertebrate fauna collected in this region and
analyzed by W. O. Addicott and J. C. Ingle, J r., sug-
gested a Pleistocene paleoclimate much cooler than
today’s and marine water conditions similar to those
of the present Bering Sea.

Washington

Geologic mapping by P. D. Snavely, J r., and J. E.
Pearl, supported by paleontological studies of
foraminifera by W. W. Rau, progressed on the so-
called Tertiary core rocks of the Olympic Mountains
in northwestern Washington. These strata record

 

GEOLOGICAL SURVEY RESEARCH 1975

two major orogenic events that may reflect con-
vergence between the Juan de Fuca and American
lithe-spheric plates. The earliest period of inferred
underthrusting involved middle and middle upper
Eocene deep-water turbidites and siltstone, which
are intensely deformed and cut by landward-dipping
thrust faults. This assemblage is represented by
mélange, composed of sheared middle Eocene silt-
stone with exotic blocks of lower Eocene basalt,
large infolded blocks of turbidite sandstone, and
broken formations. The first compressional tectonic
event was followed by regional subsidence and un-
conformable deposition of deep-water marine silt-
stone and sandstone (of latest Eocene to middle Mio-
cene age) on newly formed lower Tertiary “orogenic
crust.” In late middle Miocene, renewed underthrust-
ing along the plate boundary is inferred to have
reoccurred, and the upper Eocene to middle Miocene
strata were strongly deformed by the second episode
of compressional folding and thrusting.

In offshore basins, these structurally complex
middle Tertiary sedimentary rocks are unconform-
ably overlain by uppermost Miocene and Pliocene
siltstone and sandstone, which are gently folded
except where they have been penetrated by shale
diapirs.

COASTAL ENVIRON MENTAL STUDIES

San Francisco Bay

D. H. Peterson, T. J. Conomos, W. W. Broenkow,
and E. P. Scrivani, utilizing dissolved silica as a
tracer of seasonal nonconservative processes in the
San Francisco Bay estuary, found that physical
(conservative) processes have a strong influence on
nonconservative distributions. For example, the
effects of time-dependent phytoplankton processes
are partly controlled by the physically controlled
variations in water residence time. River discharge
provides a seasonal modulation of residence time in
the estuary. Estuarine circulation imposes a spatial
variance. Thus, it seems that both of these factors
should be considered in developing mathematical
models of processes that relate to the distribution of
nonconservative properties such as phytoplankton.

D. H. Peterson and T. J. Conomos found that the
lack of long-term current velocity and salinity field
observations representative Of a variety of spatial,
tidal, wind, and river discharge condition-s is the
major difficulty in quantifying physical processes
influencing the nontidal circulation in San Francisco
Bay. One of the more detailed surveys (State of
California, 1955) is located along one cross-channel

MARINE GEOLOGY AND COASTAL HYDROLOGY INVESTIGATIONS

section near the head of the estuary (null zone).
The data include near-hourly current velocity and
salinity observations taken over a 2-week period at
14 stations and 2 depths and therefore provide an
opportunity to estimate the tidal and nontidal con-
tributions to the freshwater and salt flux.

As expected, preliminary results indicate that the
salt flux is dominated by processes of tidal periodic-
ity. Nontidal contributions associated with the in-
fluence of the density current were found to be
negligible because these currents are weak (ap-
proach zero) in the null zone.

Results not anticipated were that the mean sea-
ward water flux attributed to the compensation cur-
rent for landward transport by the tidal wave was
large, equivalent to a river current produced by a
freshwater discharge of 170 to 230 m/s. For com-
parison, the freshwater discharge during this period,
estimated from river hydrograph data, varied from
130 to 250 m/s. These river hydrograph data showed
almost no relation to the freshwater discharge varia-
tions estimated from the cross-channel survey data.
From this anomalous behavior, it appears that non-
tidal currents near the null zone are not dominated
directly by river flow during low river discharge
conditions.

Oregon-Washington

H. E. Clifton observed on a variety of coasts—the
open coast of southern Oregon, the southeastern
coast of Spain, the eastern coast of Florida, and
sandy beaches in Willapa Bay, Wash.,——that a con-
sistent pattern of sand bed forms develops in re-
sponse to shoaling waves. The pattern can be illus-
trated by a model controlled by four variables:
maximum orbital water velocity at the sea floor,
asymmetry of this orbital velocity, wave period, and
sediment grain size. Ripples and megaripples con-
sistently tend to be asymmetric Where the landward
component of orbital velocity exceeds the seaward
component by 5 cm s“; Where the difference in
velocity is less than 1 cm s“, structures consistently
tend to be symmetric. Within the symmetric ripple
field, the size of the ripples depends directly on the
orbital diameter of the water motion if the ratio
of orbital diameter to grain diameter is less than
1,000 and directly on grain size if this ratio exceeds
5,000. The size of symmetric ripples is gradational
from the largest to the smallest ripples. In contrast,
the size of asymmetric ripples may increase abruptly
as velocity increases, similar to changes in size of
structures produced by unidirectional flow. Asym-
metric ripples migrate in the direction of wave

 

129

propagations, whereas symmetric ripples may re-
main in place as long as the generating waves do not
change significantly. Both symmetric and asym—
metric bed forms convert to a flat bed as sheet flow
develops at higher orbital velocities. The relation-
ships within the model provide a means of interpret-
ing ancient wave-worked sediment and identifying
active processes in the present-day marine environ-
ment.

ALASKA-ARCTIC CONTINENTAL MARGIN

GEOPHYSICAL, STRUCTURAL, AND RESOURCE STUDIES

Gulf of Alaska

Preliminary interpretation of deep geophysical
data in the northeastern Gulf of Alaska by T. R.
Bruns and R. E. von Huene indicated that the area
is structurally complex and consists of several areas
with markedly differing structural styles. Complex-
ity appears to increase from east to west.

Between Cross Sound and Icy Bay, there is only
one structural high, the Fairweather ground, a large
shelf-edge arch that roughly parallels the coast. De-
formed rocks, probably of Late Cretaceous to early
Tertiary age, crop out in the core of the arch. The
rest of the area is underlain by a broad basin whose-
axis lies near the coast. Between Icy Bay and Kayak
Island, the shelf is underlain by two types of struc-
tures. The first type is a series of asymmetric linear
folds Whose axes trend northeast obliquely across
the shelf. These structures are apparently less com-
plex than those on the adjacent land areas, although
some of the offshore anticlines are bounded on the
southeast by northwest-dipping overthrust faults.
The second type is a large shelf-edge arch between
Kayak Island and the Bering Trough. Its axis strikes
parallel to the coast and has a very gentle surface
dip. Between this arch and the coast is a broad
downwarp as much as 95 km Wide, perhaps contain—
ing some local unwarped areas.

The shelf between Kayak and Middleton Islands
includes a broad zone of complex structures trending
northeast, subparallel to these two islands and to the
Aleutian Trench. Structural highs tend to be asym-
metric and bounded by thrust faults on their south-
eastern limbs. Uplift and deformation are greater
than those of the Icy Bay structural trend features.
The crests of many of the highs appear to be eroded
and truncated, and thus complexly deformed Ter-
tiary rocks are exposed at the sea floor. Northwest
of Middleton Island, there are two large northwest-
trending structural highs separated by a deep basin.
These structures, which have trends divergent from

130

those of Icy Bay and Kayak and Middleton Islands,
show severe deformation on the flanks, and no struc-
ture is resolvable within their cores.‘ Middleton
Island lies on the northwestern flank of a large
northeast-trending anticline and appears to be sep-
arated from the northwest-trending structures by a
relatively deep‘ basin. Shoreward of the Kayak-
Middleton structural zone, acoustic basement ap-
pears to be high, and structure is not well defined
by the marine data. This area includes much of the
Hinchinbrook Seavalley, the Tarr Bank, and the
Copper River Delta.

Sound penetration on the seismic reflection pro-
files is generally less than 1 s (one-way time) and is
probably only within rocks of late Miocene age and
younger. Like the adjacent onshore geology, the
deeper structure offshore may be markedly more
complex than near-surface structure.

Bering Sea

D. W. Scholl studied seismic reflection records col-
lected by the U.S. Naval Oceanographic Office and
found a number of strong reflectors of “bright spots”
Within the sedimentary section of the northern Aleu-
tian Basin in the Bering Sea. The bright spots and
the anomalous deformed structures beneath them
may be indicative of significant hydrocarbon de-
posits.

A. K. Cooper interpreted the magnetic data in the
Bering Sea basin and noted a series of north-south
oceanic-type magnetic anomalies. These anomalies
have been provisionally dated as 117 to 132 my. in
age; the crust from which the anomalies originate is
thought to be the “trapped” Kula plate, which for-
merly collided with eastern Siberia and the eastern
Bering Sea margin during the Mesozoic.

M. S. Marlow and D. W. Scholl, utilizing recon-
naissance geophysical surveys of the eastern Bering
Sea margin, recognized geologic basins and three
geologic ridges beneath the shelf. The Mesozoic fold-
belt of southern Alaska has been traced from the
Alaska‘ Peninsula through the shelf to eastern
Siberia. Beneath the shelf, two of the largest basins,
Navarin and St. George, contain an estimated 8 to
10 km of Upper Cretaceous( ?) and Cenozoic strata.
The basin fill is extensionally deformed along the
flanks of these grabens and half grabens by high-
angle normal “growth-type” faults. Within the sedi-
mentary section, there is a divergence or disconform-
ity of probable Miocene age. This basinward-dipping
divergence may represent a major change in sedi-
mentation rates over the shelf as a result of a change
in the drainage of the Yukon River from the Pacific

 

GEOLOGICAL SURVEY RESEARCH 1975

to the Bering Sea. The basin fill and the thick sedi-
mentary section beneath the shelf are immediate
petroleum prospects.

COASTAL ENVIRONMENTAL STUDIES

Turnagain Arm

A. T. Ovenshine, S. R. Bar-tsch-Winkler, N. R.
O’Brien, and D. E. Lawson have accumulated evi-
dence that Turnagain Arm, a 70-km-long estuary
near Anchorage, Alaska, is flood dominant with re-
spect to its longeterm sedimentation budget. The
principal results leading to this conclusion are:

1. The sand that fills most of the arm includes sig-
nificant quantities of mineral (andalusite,
staurolite, garnet, biotite, muscovite, and chlor-
ite) and rock (pumice and coal) fragments
that could not have come from the bedrock sur-
rounding Turnagain Arm. These probably were
derived from the drainage basin of the Susitna
River and have been transported by tidal cur-
rents across Knik Arm and the upper Cook
Inlet into Turnagain Arm.

2. Clast size and imbrication directions of gravel
exposed on Girdwood Bar in 1974 indicate the
predominance of eastward transport toward
the head of the arm.

3. A transgressive deposit of intertidal sediment has
formed at Portage in response to subsidence
caused by the Alaskan earthquake of March
27, 1964. Mineral and rock fragments in the
deposit indicate that its source was seaward
in Turnagain Arm and not in the streams that
flow from the surrounding mountains into the
Portage area.

The flood-dominant character is environmentally
significant in wetland management in the upper
Cook Inlet area; there seems to be a high probability
that a portion of any solid or liquid wastes dis-
charged into Cook Inlet near Anchorage would be
driven by tidal currents into Turnagain Arm.

SHELF ENVIRONMENTAL STUDIES

Beaufort Sea

Erk Reimnitz and P. W. Barnes utilized LAND-
SAT—l and NOAA satellite imagery to make a sea-
sonal study of the shear zone between the shore fast
ice covering the inner shelf and the pack ice on the
Arctic Ocean. The midwinter shear line marks the
seaward boundary of the relatively undisturbed fast
ice and forms between the 10- and 20-m depth con-
tours along the northern coast of Alaska; its location

MARINE GEOLOGY AND COASTAL HYDROLOGY INVESTIGATIONS

appears to be controlled by bathymetry and coastal
configuration. The intensely deformed “shear zone”
forms seaward of this shear ‘line and contains a
dense pattern of major pressure ridges. This shear
zone intermittently shifts position when the ice
moves westward at approximately 5 km/d. Major
pressure ridges form during such movements, and
their keels may extend to the sea floor and plough
the bottom. Eventually, the pressure ridges become
so firmly grounded that the ice in the shear zone
resists further deformation; these winter conditions
cause (1) a seaward extension of the fast ice up to
20 to 25 km along relatively straight stretches of
coastline and (2) formation of new shear lines fur-
ther seaward. Monitoring several periods of ice de-
formation shows that the ice along the active shear
line is moving at similar or even faster rates than
the ice seaward of the Continental Shelf. Ice Within
the 20- to 25-km-wide zone remains in place well into
the period of general sea-ice breakup during the
following summer, apparently because of the exist-
ence of firmly grounded pressure ridges in this zone.

Bottom surveys‘made after the sea-ice breakup
delineate (1) a dense pattern of sea-floor gouges
produced by ice in the zone of major pressure ridges
on the central shelf and (2) a remarkably smooth
bottom landward of the midwinter shear line
(Reimnitz and Barnes, 1974). Box cores fro-m the
shear zone show that sediments are intensely mixed
(Barnes and Reimnitz, 1974).

Close inshore, the seasonal fast ice at the end of
the winter is relatively undisturbed, even where it
comes in contact with the beaches. After ice melt,
the beach face shows little evidence of ice deforma-
tion, except at shoreline promontories. Because the
energy of sea-floor processes is concentrated seaward
of 10 m depth, and not within the surf zone as it is
on lower latitude shelves, offshore construction and
shipping face formidable environmental problems
off the northern coast of Alaska.

Barnes and Reimnitz found that rivers flood prior
to the melting and breakup of the sea ice along the
Beaufort Sea coast of Alaska. This flooding causes
a freshwater overflow (1 m or more in depth) onto
the sea ice in the vicinity of river mouths. The flood-
waters carry very little sediment because the initial
melting involves only the snow overlying the frozen
soils and sediments. As the water drains through
strudel in the ice canopy offshore, the bottom is
extensively scoured. As the season progresses, the
ice immediately offshore from the deltas melts owing
to the influx of warmer river waters. Very little of
this freshwater is mixed with the seawater, and a

 

131

large freshwater reservoir results. The weak ocean
currents, the small tidal range, and the presence of
the ice cover nearby reduce mixing.

Examination of LANDSAT imagery indicates that
the rivers of the North Slope overflow in sequence
from southeast to northwest, apparently in response
to the variance of solar insolation at different lati-
tudes. Flooding of the sea ice by the Sa‘gavanirktok
River apparently began May 23, 1973, and still had
not reached its maximum extent 5 d later. During
the period of LANDSAT observation, the area of
inundated sea ice increased from approximately 18
to 48 ka. If the area were covered to an average
depth of 0.75 m, this volume would represent a
freshwater lake on the sea‘ice of at least 32X106 m3,
disregarding drainage and subsequent river flow.

Chukchi Sea

Side-scan sonar and high-resolution seismic pro—
filing equipment together with underway sampling
were used by Arthur Grantz to detail morphology
and associated sediment types in the eastern Chukchi
Sea. Detailed survey tracks were made around Cape
Lisburne, between Point Franklin and Point Barrow,
and along the northwestern perimeter of a newly
discovered grounded ice mass approximately 180 km
northwest of Point Barrow. Along each track line,
sediment samples were collected by using grabs,
gravity cores, and underway samplers. The sedi-
mentological data were then correlated with sono-
graphs taken over the sample site. The sonographs
revealed extensive regions of ice scouring that was
associated frequently with sand-wave ribbons or
fields. Large sand-wave fields, apparent current fur-
rows, and localized sharp sediment boundaries also
were observed.

Bering Sea

C. H. Nelson found that Holocene sediments from
the Yukon River form thin deposits (tens of centi-
metres) in parts of central Norton Sound and form
thick deposits (several metres) off the present sub-
delta and around the margins of Norton Sound.
These deposits typically contain thin horizons of
shells and pebbles and also thin sand interbeds that,
are flat laminated, low-angle cross laminated, and
ripple marked. The coarser grained interbeds are
interpreted to be lag deposits of storm waves and
associated storm-surge currents that have reworked
the shallow sea floor of Norton Sound (£20 m deep)
and have carried the finer grained resuspended sedi-
ment northward from the Bering Sea.

132

Well-preserved sedimentary structures are present
only in the shallowest water near the fringe of the
present Yukon subdelta; there the frequency of
formation of lag deposits is greatest, and low salinity
may inhibit benthic fauna] activity. Elsewhere in
the northeastern Bering Sea, bioturbation has de-
stroyed most wave— and current-formed sedimentary
structures.

The distribution of sediments off western Alaska
has important implications for the interpretation of
ancient epicontinental shelf sediments. Some parts
of an epicontinental shelf—«for example, Bristol
Bay—may exhibit classical gradation fro-m coarse to
fine deposits offshore. Other parts, like the Chirikov
basin, may display a complex mosaic of gravel, sand,
and mud lenses unrelated to shoreline sources. Sedi-
ment thickness, like sediment grain size, may show
no relation to source. Thick accumulations of H010-
cene sediment, apparently from the Yukon River,
cover extensive areas of the Chukchi Sea north of
nondepositional areas in the Bering Sea; only thin
accumulations occur in some places close to the
present delta. Transgressive sand and gravel layers
may be extremely thin over large regions like
margins of the Chirikov basin. Offshore epicontinen-
tal shelf sediments in a low-energy region like the
northern Bering Sea may lack preserved physical
sedimentary structures, except in areas where un-
usual conditions inhibit faunal activity.

Gulf of Alaska

Study of high-resolution seismic profiles in the
northeastern Gulf of Alaska by B. F. Molnia and
P. R. Carlson indicated that at least four distinct
sediment types are exposed on the sea floor: (1)
Undeformed Holocene sediments, (2) deformed
Holocene sediments, (3) Quaternary morainal ma-
terials, and (4) tilted, folded, and lithified Tertiary
and Pleistocene deposits. The stratigraphic relation
between the four sediment types varies from locality
to locality; not all types are present in each area.
The ages of the four types are unknown and may
vary over the study area.

Tertiary or Pleistocene deposits that may be the
Yakataga, Poul Creek, or Katalla Formations crop
out on Tarr Bank, the Middleton Island and Kayak
Island platforms, and the Pamplona Sea Ridge and
in the area south of Yakataga. Morainal materials
compose the surficial sediment near Yakutat Bay,
Icy Bay, and Bering Glacier. Holocene sediments
mantle the remainder of the shelf area, the maxi-
mum sediment thickness approaching 300 m near
the Copper River; these thick deposits commonly

 

GEOLOGICAL SURVEY RESEARCH 1975

show slump structures that may be seismically in-
duced.

West of Kayak Island, the Copper River is the
primary source of Holocene sediment. Interpretation
Of seismic profiles and LANDSAT imagery indicates
that Copper River sediment is supplied to Prince
William Sound through the Hinchinbrook entrance,
the Hawkins Island Cutoff, and the Orca Inlet and
spreads eastward toward Controller Bay. In addi-
tion, some Copper River sediment bypasses Tarr
Bank and is deposited on the Outer Continental
Shelf. East of Kayak Island, the major sediment
sources are streams draining the larger ice fieids,
notably the Malaspina and Bering Glaciers. Trans-
port of bottom and suspended sediment is predomi-
nantly westward.

GENERAL OCEANIC AND INTERNATIONAL STUDIES

Project FAMOUS

For the French-American Mid-Ocean Undersea
Study (FAMOUS), J. G. Moore participated in 6
of 13 dives made by the submerisble Alvin to the
rift-valley floor of the Mid-Atlantic Ridge at 36° N.
Project FAMOUS also included dives by the French
submersibles Archimede and Cyana. The typical dive
was to a depth of 2600 to 2800 m, traversed a dis-
tance of 700 m on the bottom, occupied four stations
Where rock, water, and sediment samples were taken,
and took several hundred photographs from external
and internal cameras. Studies made from the sub-
mersibles showed that the rift-valley floor is ex-
tremely rugged. Collection and mapping of pillowed
basaltic lava flows suggested that the age of the lava
appeared to increase systematically outward from a
1-km-wide zone at the rift-valley axis. The entire
rift-valley floor is cut by a system of cracks and
faults that are about parallel to the axis and that
increase in width and throw outwards. The width
of the cracks ranges from a few centimetres to 10 m.

Deep Sea Drilling Program

M. A. Lanphere and G. B. Dalrymple determined
K-Ar ages on basalts from three Pacific Ocean sites
drilled on legs 33 and 34 of the DSDP. The age of
crystallization of basalt is 91.2i2.7 my in hole
315A from the Fanning Island volcanic edifice in the
Line Islands. Previously, scientists from leg 33 sug-
gested that paleontologic evidence and sedimenta-
tion-rate extrapolation for sites 315 and 316 indicate
that volcanism ceased at about the same time be-
tween 79 and 85 my. ago at all three sites. They
thus concluded that the Line Islands were approxi-

MARINE GEOLOGY AND COASTAL HYDROLOGY INVESTIGATIONS

mately coeval and were not formed by movement of
the Pacific plate over a mantle “hotspot.” Lanphere
and Dalrymple believe that only the volcanism at
site 315 is precisely dated. The basalt at the bottom
of hole 165 has not been dated; because of poor core
recovery and uncertainty in the location of fossil
zones within the core, the age of basalt based on
sedimentation-rate extrapolation is ambiguous. The
minimum age of the basalt basement in hole 165
could be greater than 100 my. Basalt was not
reached in hole 136, but Campanian volcanogenic
sediments, which occur at the bottom of the hole,
suggest a minimum age of 81 to 83 my. for cessation
of volcanism. Thus, there is no evidence at this time
that the Line Islands do not become younger from
north to south, and the melting spot hypothesis must
be retained as a viable working hypothesis for the
origin of this linear volcanic feature.

The minimum age of the basalt basement in hole
317A, leg 33, from the Manihiki Plateau is 106.0i3.5
m.y., and the estimated crystallization age, based on
the relative degree of alteration of whole-rock
samples, is approximately 110 to 120 my This esti-
mated age is in reasonable agreement with poorly
preserved fossils recovered from sediments above
the basalt basement from the Bauer deep, a depres-
sion between the active East Pacific Rise to the west
and the inactive Galapagos Rise to the east.

A K-Ar age of >130: 1.5 m.y. from hole 319A,
leg 34, was measured on relatively fresh basalt. This
age should be close to the age of crystallization. It
agrees Within analytical uncertainty with the age
of 15:1 my. for the Orbulina datum, which occurs
a few metres above the sediment-basalt contact, and
with the age of the crust inferred from sea-floor
spreading rates.

Peru-Ecuador deep.sea biostratigraphy

Pliocene and Quaternary phytoplankton assem-
blages have been recovered by continuous coring at
DSDP sites 157 (2° 8.), 320 (9° 8.), and 321
(12° 8.), all about 350 km west of Ecuador and
Peru, and beyond the coastal area of strong present—
day upwelling. J. D. Bukry reported that paleoen-
vironmental indicator taxa in the phytoplankton as-
semblages show that the Quaternary water was
warmer than the upper Pliocene water, and the
upper Quaternary (Brunhes magnetic epoch) water
was especially warm. The cocolith Cocolithus pelagi-
cus, indicating cool water, is consistently present in
the Pliocene but disappeared locally in the early
Quaternary. The silicoflagellate genus Distephanus,
indicating cool water, occurs in significant numbers

 

133

(10 to 25 percent of the total population) only in the
Pliocene. In Quaternary assemblages, which are dom-
inated by the warm-water genus Dictyocha, Disteph;
anus is absent or less than 5 percent. The lowest
numbers of Distephcmus are in the youngest silico-
flagellate zone, the Dictyocha epiodon Zone, which is
correlative with the Brunhes magnetic epoch
(approximately 0.0 to 0.7 m.y.). The biogenic sedi-
mentation rate in the Pliocene, which is higher than
that in the Quaternary, at DSDP 157 probably indi-
cates more nutrients and stronger upwelling, which
also correlate with cooler surface water. This evi-
dence suggests that Quaternary large-scale air-water
circulation patterns related to glaciation nearer the
poles are associated with less upwelling at these sites
off northern South American than they were in the
Pliocene.

Marine geology from Tahiti to Panama, equatorial Pacific

H. E. Cook found that North American strati-
graphic principles, as developed by geologic mapping
on continents, can be applied to deep-sea sediments.
The ability of the DSDP to obtain long cored inter-
vals at numerous ocean-basin sites can provide suffi-y
cient data for the definition and recognition of rock
stratigraphic units (formations). Synthesis of these
data into various types of maps and cross sections
can help provide a stratigraphic and sedimentologic
framework within which our interpretations must
lie. This approach brings the Tertiary geologic his-
tory of the equatorial Pacific into better focus. This
history is complex and is not adequately explained
by a simple model of sedimentation in which deposi-
tion took place in progressively deeper water as sea-
floor spreading moved the sites westward.

Paleoequator reconstructions using chronostrati-
graphic isopachs support earlier hypotheses that, in
the middle Tertiary, the north-northwestward mi-
gration of the Pacific plate took a more west-north-
westward trend. Data in this study suggest that this
change took place sometime in the early to middle
Miocene (15 to 25 my. B.P.).

Marine geology of Line Islands, equatorial Pacific

H. E. Cook found that the po-stvolcanic strati-
graphic succession along the Line Islands is divisible
into five lithologically distinct units that can be cor-
related at least 1,200 km between JOIDES DSDP
sites 165, 315, and 316. The uppermost two units are
lithologically and stratigraphically correlative to the
east with the Clipperton Oceanic Formation, which
is recognized as far west as the East Pacific Rise.

134

Downhole induration changes (from ooze to chalk
and from chalk to limestone) are not merely a func-
tion of burial depth. The degree of cementation in
the ooze-chalk-limestone transition may depend more
on initial sediment composition and time than on
depth of burial. This independence of depth of burial
and degree of chalkification is becoming better docu-
mented as more drilling is done in deep-sea sedi-
ments.

The following people contributed to the study of
the marine geology of the Line Islands: H. E. Cook
and E. D. Jackson (USGS), S. O. Schlanger (Univ.
of California, Riverside), A. G. Kaneps, E. L. Win-
terer, and R. E. Boyce (Scripps Institution of
Oceanography), H. C. Jenkyns (Univ. of Durham),
D. A. Johnson (Woods Hole Oceanographic Insti-
tute), K. R. Kelts (Ecole Polytechnique Fédérale),
E. Martini (Geologisch-Pal'aontologisches Institut),
and C. L. McNulty (Univ. of Texas).

Results from the leg 33 “hotspot” cruise in the
Line Islands and site 165 of leg 17 indicated that flow
volcanism ceased on a 1,27 O-km-long segment of the
chain between 79 and 85 my. B.P. The similarities
of the postflow geological histories of all Line Island
sites indicate the following: (1) early to middle
Camp‘ani‘an volcanoclastic deposition, (2) Campan-
ian to Maestrichtian reef buildups nearby, and (3)
Oligocene emergence of atolls atop the ridge. No
“hotspot” hypothesis that requires systematic move-
ment of the Pacific plate over a fixed melting anom-
aly can account for the geochronology of Line Island
volcanism. Site 318 on the Tuamotu Ridge revealed
that volcanic edifices of the ridge had been built,
eroded, and capped by reefs by early Eocene time
50 my. RP. Consequently, the Tuamotu “elbow” is
probably older than the Hawaii-Emperor “elbow,”
which was recently estimated to be approximately
42 my. old. A thick section of Cretaceous volcano-
genic sediments on the Manihiki Plateau contained
flecks of native copper and signs of hydrothermal
alteration.

Submarine sediment gravity flows.—H. E. Cook
(USGS), H. C. Jenkyns (Univ. of Durham), and
K. R. Kelts (Geological Institute, Zurich) discovered.
during coring on leg 33 of the DSDP a Wide variety
of Cretaceous to Quaternary submarine sediment
gravity-flow deposits along the Line Islands. At cer-
tain stratigraphic intervals, these allochthonous de-
posits comprised up to 50 percent or more of the
section. Texturally, they ranged from beds composed
of silt-sized grains to breccias with clasts up to 2X5
cm in cross section. The sandasized debris exhibits a

 

GEOLOGICAL SURVEY RESEARCH 1975

number of primary sedimentary structures, whereas
the breccias are massive and often devoid of any
internal structures. These sediments, which contain
pelagic, volcaniclastic, and shoal-water reefal debris,
were derived from three major sources: shallow-
marine carbonate complexes along the Line Islands,
volcanic terranes in shallow and (or) deeper water,
and basinal deep-marine environments. Various
mechanisms were probably involved during their
transport and deposition. These possibly included a
spectrum from viscous, turbulent motion for the
graded and laminated sands to plasticoviscous mo-
tion (Coulomb viscous or Bingham) of a debris flow
type for the massively bedded mud-rich breccias.

Diagenesis of limestone.+—H. E. Cook found that,
during leg 33 of the DSDPKa 30-m-thick porous
dolomite sequence was cored in deep-sea sediments
along the Line Islands. In this area, the deep—marine
sediments are up to 1,000 m thick and range in age
from Santonian to Holocene. They consist of nanno—
fossil-foraminiferal oozes, ch‘alks, and limestones
with liberally interspersed sediment gravity-flow de-
posits derived from upslope basinal and shallow-
water carbonate environments. The dolomite occurs
450 m below the sea floor in Eocene sediments, yet
well above the Santonian basaltic basement at 900 m.
Its textural characteristics and stratigraphic posi-
tion strongly suggest that it-represents a dolomitized
deep-marine limestone. Details of its origin are not
yet known. Under the pro-per geologic setting, porous
dolomitized deep-marine sediments could form petro-
leum reservoirs.

ESTUARINE AND COASTAL HYDROLOGY

ATLANTIC COAST

Preliminary analyses by F. A. Johnson *of the
Edisto and Ashepoo estuaries in South Carolina in-
dicated vertically well-mixed conditions at high slack
tide. Saltwater was detected about 11 km farther up-
stream in the Ashepoo than in the Edisto because
of lower flow in the Ashepoo. This effect is expected
to be more pronounced during drought conditions.
Selected samples indicated good-quality water in
both estuaries; no pesticides were detected in the
water column, and very little was found in the bot-
tom sediments.

R. ’L. Cory and J. M. Redding (R. L. Cory, J. M.
Redding, and M. M. McCullough, 1974) completed
data summaries of 4 yr of physical, chemical, and
biological studies in the Rhode River estuary on the

MARINE GEOLOGY AND COASTAL HYDROLOGY INVESTIGATIONS

western side of the Chesapeake Bay in Anne Arundel
County, Md. At a monitor station, water at the 1-m
level ranged from 0.7° to 32.6°C, salinity ranged
from 1.05 to 14.03 ppt, turbidity ranged from 5 to
80 JTU, DO ranged from 0 to 19.8 mg/l, and pH
ranged from 6.8 to 10.1. The maximum water-level
range was 1.8 m, with a mean tide range of 0.5 m.

Daily estimates of net plant production and night
respiration of oxygen were made for an entire year
by using DO, temperature, and salinity data from
the monitor station. Net oxygen production ranged
from 0.1 to 8.6 g m—3 d—l, and nighttime oxygen
respiration ranged from 0.1 to 8.2 g m—3 d—l. Mean
monthly values of both ranged from a February low
of 0.4 to an August high of 4.5 g m—3 d—l; there was
no evidence of spring or autumn pulses. Day-to-day
variations of both values were large, and a summa-
tion of the entire year’s data indicated a balanced
system with a net production equal to night respira-
tion.

The average of the daily pH range at the monitor
station for the month of August in the years 1971,
1972, 1973, and 1974 shows the effects of Hurricane
Agnes (1972) runoff. Values are 0.90, 1.42, 1.00,
and 0.98 pH units, respectively; it appears that the
Chesapeake Bay’s metabolism decreased after reach-
ing 1.42 in 1972.

GULF COAST

The flow of the Vermilion River in southwestern
Louisiana is affected by lunar and (or) wind tides
as far upstream as Lafayette, La. (about 72 km
upstream from the Gulf of Mexico), according to
L. D. Fayard. Data from dye-tracer tests made dur-
ing a low-flow period showed no net downstream
water movement during two consecutive tide cycles.
The river cannot assimilate biodegradable wastes
during low-flow periods, and DO levels range from
2.0 to 4.0 mg/l during summer and early fall.

G. E. Seaburn and M. E. Jennings used a steady-
state digital water-quality model to assist the Florida
Department of Pollution Control in making waste-
load allocation analyses of several small estuaries on
the Florida gulf coast. In applying the model to the
analysis of DO, they learned that photosynthesis and
respiration by submerged aquatic plants in Crystal
River, a spring-fed estuary, are major factors in the
oxygen balance of the estuary. In areas of dense
submerged plants, DO ranged from less than 3 to
more than 10 mg/l over a 24-h period.

C. R. Goodwin reported that detailed bottom con-
tours of Tampa Bay, Fla., compiled from hydro-

 

135

graphic and photogrammetric data, are being in-
cluded on revised topographic quadrangle sheets of
the area. The new maps are experimental and not
intended for navigational purposes. They will be of
value for engineering, scientific, and recreational
purposes.

Results of Goodwin’s two-dimensional digital sim-
ulation modeling of the hydrodynamics of Tampa
Bay have been used by the Corps of Engineers to
help define the effects of the proposed deepening of
the main ship channel. A recent study showed that
a few large elongated islands constructed from

dredged material are more effective for inducing

beneficial circulation in the bay than many smaller
islands; flow can be directed and‘controlled to a much
greater degree with larger islands.

Goodwin’s proposal to place a one-way tide gate
on an existing culvert in a causeway in Old Tampa
Bay, Fla., may result in significant water-quality
improvement in the region at savings of well over
$0.5 million. A previous plan called for construction
of a four-lane bridge With a 100-m span. Tests, made
in conjunction with the Florida Department of
Transportation, showed that 0.34X 106 m3/ d of good-
quality water could be induced to flow through the
degraded region by installing a tide gate.

PACIFIC COAST

Parameters of a digital model, developed by
W. L. Haushild and E. A. Prych, of the stratified Du-
wamish River estuary in Washington include effects
due to flow, transport, and individual parameters
and constituents such as salinity, temperature, phy-
toplankton, BOD, and DO. Model results give phy-
toplankton growth rates and peak concentrations
that agree with those reported in the literature. The
model predicts a maximum decrease of 2 mg/l in
the average monthly DO concentration if the dis-
charge of secondary treated wastes increases from
the 1971 level of 1.05 m3/s to an anticipated rate
of 6.31 m3/s. Other study findings show that nutri-
ent concentrations in the estuary are high enough
not to limit growth of Cyclotella sp. or oval flagel-
lates, the summer “bloom” phytoplankton. Also, the
net primary productivity of periphyton responds to
changes in environmental conditions and nutrient
concentrations between the mountainous, valley,
and estuarine reaches of the Green and Duwamish
Rivers. ,

Seasonal changes in the relative influence of sedi-
ment-transport mechanisms were observed by J. L.
Glenn in the intertidal environments of three estu-

136

aries along the Oregon coast. Major changes in
transport mechanisms were related to seasonally
varying wave climate, tides, and river flows, but
other mechanisms were locally important and also
varied seasonally. During the relatively dry summer
months, sand transport by flotation was Widespread;
this mechanism was particularly effective Where
burrowing organisms produced accumulations of
sediments that protruded above the general level of
the surrounding tide flat. Generally, materials trans-
ported by flotation moved toward higher parts of
tide flats. Rain splash and sheet runoff were the
dominant transport mechanisms associated with
hard winter rains. These resulted in offshore sedi-
ment movement on tide flats located around the
estuary margins. On midestuary flats, rain splash
and sheet runoff resulted in sediment movements
from high areas to adjacent low areas. High winter
ground-water levels in supratidal deposits caused
extensive seepage and rill development across ad-
jacent exposed tidal flats. Although little sediment
was observed moving in these rills, the presence of
the rills indicates that erosion and offshore sedi-
ment movements had occurred.

 

GEOLOGICAL SURVEY RESEARCH 1975

The effect of salinity variations on exchangeable
cations in suspended sediment from the Mattole
River and estuary in California was investigated by
V. C. Kennedy and R. J. Avanzino. They found that
magnesium reached a maximum percentage of the
exchangeable cations at about 3 ppt salinity and
then decreased with further increase in salinity.
Sodium, however, increased steadily with increas
ing salinity. These results do not agree with other
results given in the literature because of differences
in the methods used for eliminating the effects of
interstitial saline water. Kennedy and Avanzino ap-
plied an interstitial water correction to the concen-
trations of exchangeable cations found in the desorb—
ing solution, whereas other investigators washed off
saline water with distilled water before desorbing
and thus shifted the adsorbed cation ratio before
the desorption step. The result is that relatively high
magnesium and low sodium contents have been pre-
viously reported as exchangeable cations on marine
sediments. The‘ study by Kennedy and Avanzino
shows the reverse to be true.

IMANAGEMENT OF NATURAL RESOURCES 0N FEDERAL AND

INDMN

The Conservation Division is responsible for
carrying out the USGS’s role in the management of
the mineral and water resources on Federal and
Indian lands, including the Outer Continental Shelf;
that role includes, in particular, the conservation,
evaluation, and development of the leasable mineral
resources and waterpower potential of these areas.
Primary functions are (1) mapping and evaluation
of mineral lands, (2) delineation and preservation
of potential public-land reservoir and waterpower
sites, (3) promotion of orderly development, con-
servation, and proper utilization of mineral re-
sources on Federal lands under lease, (4) supervi—
sion of mineral operations in a manner that Will
assure protection of the environment and the realiza-
tion of a fair value from the sale of leases and that
will obtain satisfactory royalties on mineral pro-
duction, and (5) cooperation with other agencies in
the management of Federal mineral and water re-
sources.

CLASSIFICATION AND EVALUATION OF
MINERAL LANDS

The organic act creating the USGS gave the Di-
rector the responsibility of classifying and evaluat-
ing the mineral resources of public-domain lands.
There are about 101 million hectares of land for
which estimates of the magnitude of leasable min—
eral occurrences have been only partly made. Such
appraisals are needed to reserve valuable minerals
in the event of surface disposal and to assist in de-
termining the extent of our mineral resources. Esti-
mates are based on data acquired through field map-
ping and the study of available geologic reports in
addition to spot checks and investigations made in
response to the needs of other Government agen-
cies. As an aid in this assessment of certain min-
erals, guidelines have been prepared setting forth
limits of thickness, quality, depth, and extent of a
mineral occurrence that are necessary before land
is considered to be mineral land.

 

LANDS

Classified land

As a result of USGS investigations, large areas of
Federal land have been formally classified “mineral
land.” Mineral-land classification complements the
leasing provisions of the several mineral-leasing
laws by reserving to the Government, in disposals
of public land, the title to such energy resources as
coal, oil, gas, oil shale, asphalt, and bituminous rock
and such fertilizer and industrial minerals as phos-
phate, potash, sodium minerals, and sulfur.

These reserved minerals on public lands are sub-
ject to development by private industry under the
provisions of the Mineral Leasi'ng Act of 1920. All
minerals in acquired lands and on the Outer Con-
tinental Shelf are subject to development under com-
parable acts.

Known Geological Structures (KGS) of producing oil and

gas fields

By the provisions of the Mineral Leasing Act of
1920, the Secretary of the Interior is authorized to
grant to any applicant qualified under the act a non-
competitive lease to prospect for oil and gas on any
part of the mineral estate of the United States that
is not within any KGS of a producing oil or gas field.
Lands within such known structures are competi-
tively leased to the highest bidder. During fiscal
year 1975, over 94,344 ha of onshore Federal land
were determined to be in KGS’s.

Known Geothermal Resources Areas (KG-RA)

The Geothermal Steam Act of 1970 provides for
development by private industry of federally owned
geothermal resources through competitive and non-
competitive leasing. During fiscal year 1975, 101,803
ha were included in KGRA’s, and 9,234 ha were
classified as valuable prospectively for geothermal
resources.

A total of $5,588,924 was received for 66,887 ha
leased through competitive bidding in 15 lease sales.
During fiscal year 1975, 53 noncompetitive leases
totaling 36,520 ha were issued.

137

138

Known leasing areas for coal and potassium

During fiscal year 1975, six Known Coal Leasing
Areas (KCLA) totaling 580,956 ha were defined in
North Dakota, Utah, and Wyoming. An addition of
26,981 ha was made to the known potash leasing area
in New Mexico.

WATERPOWER CLASSIFICATION—
PRESERVATION 0F RESERVOIR SITES

The objective of the waterpower-classification
program is to identify, evaluate, and segregate from
disposal or adverse use all reservoir sites on public
lands that have significant potential for future de-
velopment. Such sites are an increasingly scarce and
valuable natural resource. USGS engineers study
maps, photographs, and waterflow records to dis-
cover potential damsites and reservoirs. Topo—'
graphic, engineering, and geologic studies are made
of selected sites to determine if the potential value
is sufficient to warrant formal classification of any
Federal land within the site. Such resource studies
provide land-administering agencies with informa-
tion basic to management decisions on land disposal
and multiple use. Previous classifications are re-
viewed as new data become available, and, if the
land is no longer considered suitable for reservoir

development, itvis released for return to the unen—

cumbered public domain for other possible disposi-
tion. During fiscal year 1975, about 17,000 ha of
previously classified lands were released, and the re—
view program was carried on in 10 river basins in
the Western States and Alaska.

There is an increasing trend toward the develop-
ment of pumped-storage hydroelectric projects. By
using reversible equipment that can serve for both
pumping and generating, these developments usual-
ly provide peaking capacity at a relatively low unit
construction cost. During fiscal year 1975, USGS
engineers conducted studies on several of the most
favorable pumped-storage sites affecting Federal
lands in Idaho and Oregon.

 

GEOLOGICAL SURVEY RESEARCH 1975

SUPERVISION 0F MINERAL LEASING

Supervision of competitive and noncompetitive
leasing activities to develop and recover leasable
minerals in deposits on Federal and Indian land-s is
a function of the USGS, under delegation from the
Secretary of the Interior. It includes (1) geologic
and engineering examination of applied-for lands
to determine whether a lease or a permit is appro-
priately applicable, (2) approval of operating plans,
(3) inspection of operations to insure compliance
with regulations and approved methods, and (4)
verification of production and the collection of
royalties. (See table 2.)

Before recommending a lease or permit, USGS
engineers and geologists consider its possible effects
upon the environment. Of major concern are the
esthetic value of scenic and historic sites, the preser-
vation of fish and wildlife and their breeding areas,
and the prevention of land erosion, flooding, air pol-
lution, and the release of toxic chemicals and danger-
ous materials. Consideration is also given to the
amount and kind of mining-land reclamation that
will be required.

Louisiana and Texas Outer Continental Shelf lease sales

for oil and gas

Four sales of Federal Outer Continental Shelf
leases for oil and gas were held in fiscal year 1975.
In sales held in July 1974, October 1974, February
1975, and May 1975, 1,353 tracts comprising
2,807,390 ha were offered for lease. High bids total—
ing $1,966,099,135 were accepted for 732,438 ha in
326 tracts. USGS geologists, geophysicis-ts, and engi-
neers evaluated each tract offered to insure receipt of
fair market value to the Government.

COOPERATION WITH OTHER FEDERAL

AGENCIES

The USGS acts as a consultant to other Federal
agencies in land-disposal cases. In response to their

TABLE 2.—Mineral production, value, and royalty for fiscal year 1975 1

 

 

. Gas - - 2 alt

Lands (4022.5) cugz‘fisefigs) Gliiiicégids (9:33:35) (33315:) (15353;)
Public ____________________________ 22,688,000 30,449,000 1,939,637,000 41,833,000 $1,855,600,000 $196,945,000
Acquired _________________________ 827,000 875,000 14,054,000 685,000 186,671,000 11,755,000
Indian ____________________________ 4,128,000 3,405,000 203,274,000 21,128,000 332,054,000 41,761,000
Military __________________________ 47,000 666,000 81,964,000 ________ 11,548,000 1,852,000
Outer Continental Shelf ____________ 46,156,000 92,686,000 7,839,425,000 1,426,000 3,546,667,000 553,037,000
Naval Petroleum Reserve No. 2 _____ 272,000 110,000 52,354,000 ________ 14,619,000 1,691 00
Total _____________________ 74,118,000 128,191,000 10,130,708,000 65,072,000 5,947,159,000 807,041, 00

 

‘ Estimated in part.

2 All minerals except petroleum products; includes coal, potassium, sodium minerals, and so forth.

MANAGEMENT OF NATURAL RESOURCES ON FEDERAL AND INDIAN LANDS 139

requests, determinations are made as to the mineral vision that are proposed for sale, exchange, or other
character and water-resource development potential disposal. About 15,000 such reports were made dur-
of specific tracts of Federal lands under their super- ing fiscal year 1975.

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES,
AND TECHNIQUES

EXPERIMENTAL GEOPHYSICS
HEAT FLOW

Geothermal setting of Long Valley caldera

Heat-flow and heat-production measurements have
been made by A. H. Lachenbruch, J. H. Sass, R. J.
Munroe, and T. H. Moses, Jr., in the vicinity of Long
Valley 0 to 30 km from the rim of the caldera and up
to 30 km on either side of the boundary of the Basin
and Range province at the eastern scarp of the Sierra
Nevada. The data show no conspicuous effect of the
province transition, possibly a small local heat-flow
anomaly near the caldera’s eastern rim and a very
substantial anomaly near the western rim. Simple
heat-conduction models suggest that Long Valley
caldera is the surface expression of a deep magmatic
system; an upper crustal magma chamber probably
could not have sustained molten material throughout
the 2-m.y. eruptive history unless it was resupplied
with heat from deep crustal magmatic sources. Ther—
mal models for the near-normal heat flow at the
eastern rim justify speculation that magma beneath
the eastern part of the caldera was exhausted during
the eruption of the Bishop Tuff 0.7 m.y. ago and that
the resurgent dome, which subsequently formed in
the west-central caldera, marks the location of a
residual chamber more circular in plan. High heat
flow indicated by the single measurement near the
western rim can be attributed to a simple shallow
magma chamber beneath the western caldera or to
recent local magmatism along the Sierra frontal fault
system.

Near-surface hydrothermal regime of Long Valley caldera

Temperature measurements in 29 shallow holes
(~30 m) drilled by R. E. Lewis in Long Valley cal-
dera were interpreted by A. H. Lachenbruch, M. L.
Sorey, R. E. Lewis, and J. H. Sass. Temperatures at
5- to 10-m depths can be contoured systematically;
they correlate well with the character of the thermal
gradient to 30 m. Where the temperature at a depth
of 10 m is less than 11°C (group I), the gradients to

140

 

30 m are practically zero; Where the 10-m tempera-
ture is between 11° and 16°C (group II), the gradi-
ents are 200° to 400°C/ km and uniform, correspond-
ing to conductive heat flows of 4 to 8 HFU. Where
the 10-m temperatures exceed 16°C (group III),
gradients are larger and irregular with local heat
flows to 50 HFU. Thermal considerations suggest
that the first group represents hydrologic recharge,
the second group a conductive regime to substantial
depth, and the third group hydrologic discharge. This
interpretation is supported by limited drilling to
depths up to 300 m. Regimes in the first group in the
peripheral part of the caldera suggest that it is an
area of recharge. The hot springs discharge in a fault
zone characterized by near-surface regimes in groups
II and III; chemical evidence indicates that their
source temperature is about 200°C. Evidently, the
springs are fed by local fractures; if the background
regime is conductive, their source is probably less
than 1 km deep. Hydrologic and isotopic data indi-
cate that gross circulation in the hydrothermal sys-
tem is from west to east and suggest that the hot
springs gain their heat in the western part of the
caldera. The large amount of heat presently being
removed from the caldera by flowing water and the
inference that hydrothermal activity was more in-
tense in the past support the view that Long Valley
has been resupplied frequently with heat from deep
magmatic sources throughout its eruptive history.

Heat flow at The Geysers. California

T. C. Urban (USGS), I. M. Jamieson (Pacific Ener-
gy Corporation), and W. H. Diment and J. H. Sass
(USGS) (1975) have analyzed temperature profiles
in three cased holes close to thermal equilibrium over
a known part of The Geysers steam field and in one
hole near Cloverdale some 13 km to the west. The
linearity of the temperature curves to the maximum
depths examined (200 to 1000 m) suggests conduc-
tive transport of heat. Moreover, linear extrapola-
tion of these temperatures to the depth of “first
steam” (where known) yields a temperature close

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

to that of the steam reservoir, which is generally re-
garded as about 240°C. It is thus suggested that heat
transport is mainly conductive through the whole
interval between the surface and the reservoir, at
least at this locality. It is also suggested that the
reservoir temperature has remained relatively con-
stant for thousands of years. Heat flows of greater
than 3 “cal/cm2 s for Cloverdale and 9, 11, and 12
iical/cm2 s for the three holes over the known por-
tion of the field were estimated. Elementary calcula-
tions show that the conductive heat removal in and
about the field is very small relative to that of pres-
ent steam production but that energy stored above
ambient temperature is large with respect to annual
steam production.

Heat flow on the southern flank of the Snake River rift

Rifting in southern Idaho has been active for some
time. Holocene volcanism, abundant hot springs, and
hot-water wells attest to an anomalous geothermal
regime. Preliminary heat flows obtained in this re-
gion by T. C. Urban and W. H. Diment (1975) are as
high or higher than most in the Basin and Range
province to the south. The “reduced” heat flows
(those obtained after allowance is made for the
radioactive heat production of the igneous rocks)
also are high with respect to those in the Basin and
Range. The highest values are from holes in the Raft
River valley, and they probably reflect hydrothermal
convection at depth.

Convective heat flow at Yellowstone National Park

The estimated heat discharged by chloride-rich
thermal waters east of the Continental Divide in
Yellowstone National Park was reevaluated by R. O.
Fournier, D. E. White, and A. H. Truesdell by means
of a chloride inventory method. Flow rates and
chloride contents of rivers draining regions of hot-
spring activity were measured, and chloride contents
and temperatures of deep hot-water aquifers were
calculated by using compositions of spring waters.
This information provided estimates of the volume
of hot-spring water reaching the rivers and the
original heat content before adiabatic and conductive
cooling. The heat discharged by spring water above
4°C (the mean annual temperature) in the Madison
River drainage is 6.4><10S cal/s and in the Yellow-
stone River drainage is 4.0X108 cal/s. The Upper,
Midway, Lower, and Norris Geyser basins discharge
into the Madison‘ River drainage. West Thumb, Mud
Volcano, and Mammoth basins discharge into the
Yellowstone River drainage. The convective heat flow
due to thermal waters within the portion of the Yel-

 

141

lowstone caldera draining to the east of the Conti-
nental Divide (2,313 kmz) is 9.3)(10S cal/s, and the
average heat flux is 40 ,ucal/cm‘z s.

Oxygen-18 in chert as an indicator of ancient geothermal

gradients

Irving Friedman analyzed oxygen-isotope abun-
dances in diatoms and various forms of chert col-
lected by K. J. Murata from Miocene rocks of the
Temblor Range, Calif. The analyses suggest that the
diatoms grew at 21° to 28°C, the cristobalitic chert
formed at about 45°C, and the quartzitic chert
formed at 80°C. These temperatures can be trans-
lated into geothermal gradients and indicate a low-
er heat flow in the Miocene in the Temblor Range
(0.75 “cal/cm2 s) compared to the present value of
1.3. Similar analyses of cherts from the Monterey
Shale in the Taft area show that the Miocene geo-
thermal gradient was normal (heat flow~1.2 heal/
cm2 s) in that area.

ROCK MAGNETISM

Paleomagnetic intensities of subaerial and submarine basalts

S. C. Grommé (USGS) and Michel Prévot (Univ.
of Paris) (1975) compiled measurements of the in-
tensity of remanent magnetization for 177 subaerial
basalt flows ranging in age from historic time to 10
my. and for 204 submarine basalt samples from the
North Atlantic basement. No significant difference in
mean intensity is observed between subaerial basalts
younger than 700,000 yr and older, normally mag-
netized basalts, and, after partial demagnetization in
200 Oe, no difference is seen between historic basalts
and older basalts of either polarity. Grommé and
Prévot conclude that (1) no significant decay in the
intensity of remanent magnetization in subaerial
basalt occurs for several million years after eruption
and (2) no large increase of the geomagnetic field
intensity occurred during the Brunhes normal polari-
ty epoch and, hence, such an increase cannot be the
cause of the larger amplitude of the axial magnetic
anomaly over midocean ridges. For oceanic basalts,
the mean intensity of magnetization decreases by
about two-thirds from the bottom of the median val-
ley to the flanks of the ridge. This diminution is com-
parable to the parallel decrease in amplitude of mag-
netic anomalies and results from low-temperature
oxidation of titanomagnetite.

Magnetism in deep-sea basalts of the Nazca plate, eastern
Pacific Ocean
Magnetic properties of basaltic basement rocks
from the Nazca plate that were obtained on leg 34 of

142

the DSDP were investigated by S. C. Grommé and
E. A. Mankinen. Paleomagnetic inclinations measured
in the drill cores indicate that no detectable change
in the latitude of the Nazca plate has occurred since
late Eocene time. Evidence of moderate to extreme
low-temperature oxidation of titanomagnetite to
titanomaghemite was found in all samples. This oxi-
dation has not affected most of the paleomagnetic
directions but in one case has proceeded far enough
to cause a self-reversal of natural remanent mag-
netization. Oxidation has markedly reduced the in-
tensity of magnetization and the susceptibility but
appears to have increased the coercivity of remanent
magnetization. An improved method of alternating-
field demagnetization has been found necessary to
remove secondary magnetizations acquired by these
rocks during the drilling operations.

Paleomagnetic dating of Pleistocene lava flows, Grand Canyon,

Arizona

Upper Pleistocene lava flows have dammed the
Colorado River in the lower Grand Canyon, Ariz., on
two or more occasions. Paleomagnetic measurements
made by S. C. Grommé and E. A. Mankinen on 32
erosional remnants of these basalts show normal
polarity, which indicates that the formation of the
lava dams and their subsequent breachings all oc—
curred within the last 950,000 yr and most probably
within the last 700,000 yr. The two main groups of
natural magnetization directions that are observed
may represent two main pulses of eruptive activity
because the same shift in direction occurs in two
separate stratigraphic sections and corresponds ap-
proximately to a known erosional interval.

Analysis of paleolatitudes and paleomagnetic inclinations in the

northwestern Pacific area

A method of analysis was developed by A. V. Cox
for obtaining correct paleolatitudes from paleomag-
netic inclinations that are measured in azimuthally
unoriented vertical drill cores. The correction factor,
derived from probability arguments and added to the
apparent paleolatitude to obtain the true one, ranges
from 13° at 71° latitude to zero at the equator. Con-

fidence limits for paleolatitudes have been derived.

from an empirical model for paleosecular variation.
The correctness of the paleolatitude correction and of
the confidence limits has been confirmed by compar-
ing them with Quaternary paleomagnetic data from
Nun-ivak and the Pribilof Islands, Alaska. This meth-
od of analysis has also been applied to paleomagnetic
inclinations measured in cores of Cretaceous basaltic
basement obtained by the DSDP from the Pacific

 

GEOLOGICAL SURVEY RESEARCH 1975

plate. The inclinations have been combined to give a
paleomagnetic pole that is very close to the one ob-
tained by earlier workers, who used magnetic anoma-
ly data over Cretaceous seamounts in the Pacific.

Precambrian magnetic reversals and polar wandering: application

to geologic correlations between Arizona and Montana

The geomagnetic polarity chronology recorded in
the Unkar Group and overlying Nankoweap Forma-
tion of the Precambrian Grand Canyon Supergroup
in northern Arizona was found by D. P. Elston to
consist of a very long interval of normal polarity fol-
lowed by at least five brief periods of reversed polari-
ty. Preliminary results indicate a similar pattern in
much of the Precambrian Belt Supergroup of Mon-
tana. The onsets of reversals in these two sedimen-
tary rock sequences apparently represent the same
point in time, a point that is also broadly indicated
by the results of radiometric dating. This correlation
means that the middle part of the Snowslip Forma-
tion of the Missoula Group of the Belt Supergroup is
equivalent to the upper middle part of the Dox Sand-
stone of the Unkar Group. Most of the preliminary
polar wandering path obtained from the Belt Super-
group does not coincide with the established polar
wandering path for the Grand Canyon Supergroup.
Points on the two paths corresponding to a time of
1,100 my. ago are 30° of arc apart. This discordance
suggests that the Belt Supergroup was transported
to its present position relative to the Arizona Pre-
cambrian rocks some time in latest Precambrian or
earliest Paleozoic time.

Reversed magnetic polarity in lavas from Antarctica

Lava cores recovered from two boreholes in the
McMurdo Volcanics of Antarctica by the Dry Valley
Drilling Project were investigated by H. R. Spall. All
the lavas have reversed magnetic polarity, which in-
dicates that they are older than 700,000 yr. A de-
tailed study of one 44-m-thick lava flow has shown
that it is magnetically very stable and that, when
the lava was erupted, the paleointensity of the geo-
magnetic field was about 0.1 Oe, about one-fifth of
its present value.

COMPUTER MODELING

Earthquake modeling

D. J. Andrews reported that, from computer mod-
els of earthquakes in seismic gaps, systematic rela-
tionships were found between the energy and
moment of an earthquake and the parameters char-
acterizing the initial state. From more detailed

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

models of the rupture front, it was found that energy
must be absorbed for other components of shear
stress to be finite.

W. D. Stuart proposed a model invoking extensive
fault creep before earthquakes to explain transient
geophysical phenomena observed before earthquakes.
The model so far appears to be consistent not only
with published observations but also with recent sur-
face tilt anomalies associated with moderate earth-
quakes on the central San Andreas fault. The dila-
tancy fluid-diffusion hypothesis currently in fashion
seems to be incompatible with the tilt data. Unlike
the fluid-diffusion model, the premonitory creep
model suggests that substantial slip on the fault
plane near the focal region occurs before the earth-
quake and is accompanied by decreasing shear
stresses. In this construct, the earthquake plays a
minor role in fault dynamics, although, of course, it
causes the greatest cultural damage.

Resistivity interpretation

A. A. R. Zohdy developed the necessary formulas
for the calculation of the various bipole-dipole ap-
parent resistivity maps that will be obtained when a
current bipole is placed near a vertical contact sepa-
rating two homogeneous and isotropic media of dif-
ferent resistivities. The azimuth of the current bi-
pole with respect to the strike of the surface trace of
the vertical contact is variable. The problems where
the current bipole is on one medium and where the
bipole straddles the contact were both solved. A com-
puter program for the bipole-dipole simple total-field
apparent resistivity was written by R. J. Bisdorf.
The calculation of such maps will be valuable in in-
terpreting field surveys that have already been made
in Long Valley and Hollister, Cal-if, Raft River valley
and the Snake River Plain, Idaho, and other geo-
thermal areas.

GEOMAGNETISM

Geomagnetic observatories

Recordings of the temporal variations in the three
components of the Earth’s magnetic field (horizontal
intensity, vertical intensity, and direction) were
made at a worldwide network of 12 geomagnetic ob-
servatories. Absolute field measurements are made
every few days at each of the observatories to pro-
vide baseline control and to provide data for long-
term geomagnetic secular change studies. Recordings
and observations are disseminated to the world sci-
entific community through the World Data Centers.
J. D. Wood is responsible for the operation of the

 

143

observatory network, and R. J. Main is responsible
for data processing and quality control.

Repeat magnetic surveys

Measurements and recordings of absolute values
and variations in the direction and in the horizontal
and vertical intensities of the Earth’s magnetic field
are acquired at more than 200 repeat stations scat-
tered throughout the conterminous United States,
Alaska, and the Pacific islands. These data are pri-
mary input to the compilation of the U.S. and World
Magnetic Charts and to magnetic secular change
studies. Twenty stations were occupied in 1974 (in
Eastern and southeastern States) to complete the
U.S. data collection for the 1975 U.S. and World Mag-
netic Charts. The observation program was planned
by J. D. Wood, and field work was accomplished by
G. W. Brougham. The repeat survey data are de-
posited in the World Data Centers for worldwide
distribution. As part of the master field of U.S. mag-
netic data, these data are a major source‘of input to
the nautical and aeronautical chart navigation data.
The nautical and aeronautical chart circulation ap-
proaches 50 million copies per year.

U.S. and world magnetic charts

Under the direction of E. B. Fabiano, magnetic
data from more than 600,000. surface, marine, and
aeromagnetic measurements from 1939 to 1974 were
used to prepare magnetic charts of the United States
and the world for epoch 1975. The U.S. chart series
consists of separate charts for inclination, horizontal
intensity, vertical intensity, and total intensity
prepared every 10 yr, plus _a chart of declination
(compass variation) prepared at 5-yr intervals
(Fabiano, 1975). Preliminary results show that the
high rate of secular change in the United States has
been sustained or increased, particularly in. the
southeastern United States. The maximum rate of
change is 120 nT (gammas) per year off the south—
ern coast of Florida.

A mathematical model using 168 spherical har-
monic coefficients for the main field and 80 coeffi-
cients for the secular change field is being used to
prepare the world magnetic charts. The complete
series of world charts for five magnetic components
will be published by the Defense Mapping Agency.
Preliminary evaluation of this model shows an over—
all root-‘mean-square residual fit of less than 200 nT
for the main field and 6 nT for the secular change
field.

144

Geomagnetic instrumentation

R. W. Kuberry and A. W. Green, Jr., completed the
design of a new geomagnetic data acquisition system
for the US. magnetic observatory network. The sys-
tem employs a three—component fluxgate magnetome-
ter as well as a proton magnetometer. The com-
ponents of declination, horizontal intensity, and
vertical intensity, plus total field, are available in
both analog and digital forms in real time. Perma-
nent records are made on 1/2-inch digital magnetic
tape and on analog paper charts (in world standard
observatory formats). The new systems, which are
being installed at selected geomagnetic observatories,
will provide a computer-compatible product to inves-
tigators in the USGS and in the world scientific
community.

Geomagnetic secular change

L. R. Alldredge completed a study of the causes of
the rather sudden changes in the rate of change of
geomagnetic components at observatories. Some sci-
entists assumed that the “impulses” came from the
core of the Earth. This idea demanded conductivities
in the mantle that were orders of magnitude less
than those derived from other concepts. Alldredge
(1975) showed that the “impulses” could be ex-
plained by the sunspot cycle and the related west-
ward-flowing ring—current variations. Alldredge was
further able to quantify the first—order effects of the
11-yr solar cycle on the observatory component
values and to derive a prediction for them that may
hold 5 to 10 yr ahead and be useful in prediction.

D. G. Knapp, through modeling studies of the main
geomagnetic field, has shown that the quadrupole
field of the Earth has undergone a fairly constant
rotation of 15 min of are per year for the past sev-
eral decades. The center of this clockwise rotation is
in the north Pacific Ocean near the Gulf of Alaska.

Long-period geomagnetic field variations

W. H. Campbell analyzed geomagnetic records
from 64 world observatories by computing variation
amplitude spectra for the period range from 5 min
to 4 h. A search was made for systematic behavior
in the spectral composition that could be associated
with time of day, season, solar cycle, activity level,
component direction, or geographical location of the
station. No consistent frequency location for peaks
in spectral composition was found. Rather, the dis-
plays of spectral amplitudes A were mostly “linear”
in form, often obeying A~T"‘, where T is the period.
The spectral slope m was usually close to 1.0 but

 

GEOLOGICAL SURVEY RESEARCH 1975

varied at times from 0.5 to 2.0. The amplitudes al—
ways showed a maximum at the auroral zone lati-
tudes, a minimum near 20° to 40°, and a minor
maximum near the equator. The positions shifted
equatorward with increasing activity. The relative
growth in amplitude with rising activity varied with
latitude. Seasonal peaks in activity were found in
equinoctial months. A summertime minimum occur—
red at auroral zone stations; elsewhere, an enhance-
ment occurred during the summer. General findings,
emphasizing the North American Hemisphere and
1965, are presented in a number of tables and graphs
(Campbell, 1976). Since induced currents from
geomagnetic variations can interfere with corrosion
monitoring systems on long fuel pipeline-s and can
contribute to corrosion, particularly at auroral lati-
tude and equatorial electroject locations, this study
is being used to evaluate potential induced—current
problems on the Alaska oil pipeline.

Source fields of geomagnetic pulsations

A. W. Green, Jr., conducted theoretical and experi-
mental studies on the source fields of geomagnetic
pulsations in the frequency range from 10—3 to 10—1
Hz. This study is aimed at achieving a better under-
standing of natural electromagnetic sources used in
magnetotelluric investigations of the Earth’s crust.
A specific objective is to determine the relative roles
played by “wavelike” and “currentlike” sources in
the production of anomalous vertical electric- and
magnetic-field components that give rise to erroneous
geologic interpretation and data scatter. As part of
the experimental program, Green has built a system
for sensing and recording all six components of the
electromagnetic field in the range from 10—3 to 2.0 Hz
and placed it in operation at the Boulder magnetic
observatory.

As another part of this research, A. W. Green, Jr.,
and C. O. Stearns (USGS) and V. A. Troitskaya (In-
stitute of Physics of the Earth, Moscow, USSR.)
have been studying the relationship between the
worldwide characteristics of geomagnetic pulsations
and some parameters of the Earth’s magnetotail.

Simultaneous high-resolution recordings of geo-
magnetic pulsations of the class Pi 2 have been ana-
lyzed at a network of 10 Soviet and US. observa-
tories. Analysis of spatial amplitude patterns sug-
gests that the Pi 2 source is along the geomagnetic
field lines in the midnight meridian, which pass
through the inner edge of ,the magnetotail plasma
sheet. The Pi 2’s were treated as aperiodic events,
and a spectral analysis was made by the Fourier in-

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND‘TECHNIQUES

tegral transform method. The dominant spectral
peaks were shown to be harmonically related and
glob-ally coherent. A significant result of this investi-
gation is the discovery of large-amplitude power
spectra peaks at periods much longer than the
“visual period” and of the order of 300 s. The fre—
quencies of these peaks are in excellent agreement
with a theoretical magnetohydrodynamic model of
Pi 2 generation at the plasma sheet edge, followed by
guided-mode propagation along a narrow field-line
path. Inasmuch as the theoretical model is frequency
sensitive to the position of the edge of the magneto—
tail plasma sheet, observed shifts of the longest
period spectral peak in the computed data are be-
lieved to be diagonostic of the position of the plasma
sheet edge and the auroral oval.

APPLIED GEOPHYSICS TECHNIQUES

Resistivity of oil shales

Vertical electrical soundings by D. L. Campbell in
the Piceance basin, 0010., showed coefficients of elec-
trical macroanisotropies in the lower oil shales rang-
ing from about 2 in the basin center to about 9 on the
flank of the basin. These are among the largest
macroanisotropies ever reported and are probably
due to a complex of isolated horizontal aquifers with-
in the lower part of the shale section. Laboratory
measurements on a rich oil-shale sample from the
Piceance basin indicate a value of 2.1 for the coeffi-
cient of electrical microanisotropy. The field study
indicates that the “leached zone,” an aquifer in the
upper Green River Formation oil sh'ales that is well
defined near the basin center, splays into many thin
water-bearing horizons extending throughout the oil-
shale section toward the basin flanks. These thin
horizons are probably recharged through a complex
of near-vertical fissures that appears to become
denser and to penetrate more deeply toward the basin
flanks.

Electrical soundings in the Triassic basin

A resistivity study of the Deep River Triassic
basin near Durham, NC, by H. D. Ackermann
showed a marked resistivity contrast between the
Triassic rocks and the underlying metasedimentary
and plutonic rocks. The thickness of the Triassic
rocks was determined by 32 Schlumberger soundings,
and the interpretation of one of the soundings agreed
with the depth to pre-Triassic basement projected
from a nearby deep well. Resistivity surveys appear
to be the most effective geophysical method yet

 

145

tested for investigating the depths and internal
structures of the Triassic basins.

Digital magnetotelluric system developed

W. D. Stanley, in cooperation with the National
Bureau of Standards, built and tested a magneto-
telluric system using a three-component cryogenic
magnetometer. The magnetometer has a sensitivity
of better than 10—“, a frequency response of 1
kHz, and a dynamic range of 500 nT. A lightweight
cartridge-type digital recorder provides 12-bit digiti-
zation of the 3 magnetic-field and 2 electric-field
channels. The recorder has a communications output
interface so that data can be sent over standard
telephone lines from the field to USGS computers. A
microcomputer system currently under development
will be used as a system controller and for processing
magnetotelluric data in the field to make for more
efficient field operations. The magnetotelluric sound-
ing system has been tested in Yellowstone National
Park and will be used in its initial field applications
for detecting deep conductive hydrothermal systems
and for investigating possible heat sources, such as
magma chambers. It is capable of magnetotelluric
soundings to depths of 100 km and will thus provide
information on the electrical properties of the upper
mantle. The basic instrument system can also be used
for making controlled-source electromagnetic sound-
ings and direct-current and magnetostatic mapping
to depths of 3 to 5 km.

Logging of waste-disposal wells

W. S. Keys and A. E. Hess made geophysical well
logs of waste-injection and waste-monitoring wells at
Stuart, Fla., to determine the zones of highest per-
meability and porosity suitable for waste injection
and to locate zones of low permeability that would
prevent contamination of overlying aquifers. Tem-
perature, natural gamma, caliper, density, acoustic
velocity, neutron, resistivity, and acoustic televiewer
logs were run. The acoustic velocity logs indicate
porosities in the range of 10 to 35 percent for lime-
stone and 15 to 40 percent for dolomite. Numerous
fractures located and oriented from the televiewer
pictures have a mean angle of dip 54° to the south-
east. The logs suggest that the porosities are gen-
erally high in the two wells having two well-defined
zones of high permeability, one at about 610 m and
one near the bottom of each hole below 884 m. Resis-
tivity measurements indicate that, in permeable
zones below 884 m, water resistivity may be less than
0.18 ohm-m, or the equivalent of approximately
35,000 m/l of dissolved solids.

146

Cauldron near Silver Cliff, Colorado

A gravity survey by M. D. Kleinkopf and D. L.
Peterson defined a 12-mGal gravity low that was
interpreted as indicating a previously unrecognized
volcanic subsidence cauldron about 4 km northeast
of Silver Cliff, Colo. Subsequent surface geologic
studies verified the feature, which is expressed as a
topographic depression covered mainly with rhyolite
tuff and breccia and surrounded by Precambrian
gneiss. Three-dimensional modeling of the gravity
data indicates that about 1,000 m of low-density ma-
terial fills the subsidence feature.

A new satellite model of the geomagnetic field

J. C. Cain, W. M. Davis, and R. D. Regan recently
constructed the most detailed satellite model yet pro—
duced using data from the Polar Orbiting Geophysi-
cal Observatories. Three spacecraft, POGO—l, 2, and
3, carried rubidium-vapor magnetometers that meas-
ured the Earth’s magnetic field from late 1965
through 1970 at altitudes ranging from 397 to 1,500
km at all latitudes. This model was derived by sepa-
rating from the measured field readings the effects
of the electrical currents in the ionosphere and the
magnetosphere. The resulting model, the most pre-
cise so far calculated: ‘ represented the data to an
accuracy of only 3 nT (the Earth’s field range-s from
24,000 to 72,000 nT). The results of this work show
that the signals from the magnetized crust have half
wavelengths as large as 1,400 km. It was previously
thought that the geological structures were much too
small to have such a large scale. This result is being
evaluated for its relation to new developments in
global tectonics.

Smaller magnetic features have also been observed
in central and western Africa, at several locations in
the oceans, and near Kursk in the U.S.S.R. This last
anomaly is the most intense and appears to be as-
sociated with the 200,000-nT anomaly observed near
the surface. The Russian-s had previously claimed
that this feature was very narrow and was not de
tectable at aircraft altitude-s of 3 km. Although none
of these newly discovered magnetic anomalies have
yet been interpreted, they must arise from intensely
magnetized material covering areas of several hun-
dred kilometres.

Exploration for uranium

T. W. Offield directed a study of a uranium area in
the Texas coastal plain involving (1) aerial and
ground magnetometry and very low frequency
(VLF) electromagnetic surveys; (2) aerial four-

 

GEOLOGICAL SURVEY RESEARCH 1975

channel gamma-ray spectrometry, multiband pho-
tography, and thermal infrared imagery; (3) induced
polarization profiling; (4) resistivity profiling and
soundings; and (5) gravity profiling. Preliminary
analysis of the field data indicates that ground mag-
netic profiles show significant differences between
the oxidized and reduced geochemical cells on op-
posite sides of shallow uranium roll fronts. Conglom-
eratic channel fillings (potential uranium host rocks)
in the Gatahoula Formation have higher thermal
inertia than surrounding rocks and commonly show
in predawn thermal images as distinctly warm areas.
Study by B. D. Smith, J. W. Cady, J. J. Daniels, and
D. L. Campbell of the induced polarization pseudo-
sections suggests very subtle effects associated with
either uranium roll fronts or the geochemical changes
across them. As the metallic mineral content of the
rocks is extremely small, the observed polarization
effect may relate in part to variations in clay min-
eralogy associated with the occurrence of ore. In
ground VLF profiles taken by J. N. Towle and V. J.
Flanigan, conductivity variations were not indicative
of ore bodies but served to distinguish between dry,
wet, and silicified fault zones.

Exploration for coal

W. P. Hasbrouck and M. L. Botsford conducted
experiments in the Powder River Basin of Wyoming
to evaluate the effectiveness of gravity exploration
in locating the edges of thick‘ and strippable coals
and to develop a magnetic method to assist geologists
in mapping the boundary between burned and un-
burned coals. Preliminary indications are that high-
precision gravity surveys can be used to trace the
sharp edge of a thick seam and that magnetic sur-
veys indicate the extent of a~burned-coal facies. If
these early findings are substantiated, better esti-
mates of strippable coal reserves can be made with

~ much less costly exploratory drilling.

West Texas ground-water study

Three test holes drilled in Culberson, Jeff Davis,
and Pres-idio Counties, Tex., substantiated the inter-
pretation of vertical electrical soundings made by
W. D. Stanley. A hole near Valentine confirmed that
a 10-ohm—m zone interpreted from resistivity data
was a tuff unit with good-quality water. Another
hole near Van Horn also confirmed the resistivity
interpretation of a good producing aquifer down to
340 m. A third hole, southwest of Van Horn, pene-
trated a, massive clay aquiclude predicted by the
resistivity interpretations.

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

Electromagnetic fields about grounded wire

Formal mathematics and computer programs were
developed for computing all three components of
both electric and magnetic fields on or above the sur-
face of a layered Earth for a grounded dipole or
finite wire source. The computer programs, according
to W. L. Anderson, are designed to use either im-
proved numerical integration techniques or convolu-
tion for evaluation of the integrals. In addition to the
fields themselves, coupling ratios are computed for a
number of special cases. The results can be expressed
in either the frequency domain or the time domain.

Geomagnetic field models in magnetic surveys

As part of the satellite magnetometer experiment,
R. D. Regan and J. C. Cain have studied the utility
of geomagnetic field models in the reduction of mag-
netic survey data. The results are directly applicable
to standard magnetic surveys where global geomag-
netic field models, usually computed from spherical
harmonic series, are becoming of increased import-
ance. Basically, when used correctly, a numerical
model of sufficient complexity, including adequate
secular variation correction, provides a suitable
representation of the regional field. The best known
and mostly widely used of the available field models
is the International Geomagnetic Reference Field
(IGRF). However, the IGRF may not be suitable for
the reduction of all magnetic survey data because of
its' imperfect fit to the main field, particularly for
the years since 1963.

A possible transform fault at Kilauea Volcano

Self-potential (SP) studies in the lower eastern
rift zone of Kilauea Volcano in Hawaii by C. J. Za-
blocki revealed a small-amplitude linear anomaly
about 1 km in length and trending transverse to the
direction of the rift. This feature, near Puu Honuau-
la, coincides with a general epicentral area of recur—
rent shallow earthquake swarms and with an ap-
parent offset in the rift zone. A possible interpreta-
tion is that the SP anomaly is caused by a permeable
vertical fracture containing hot water from a heat
source at depth. Ground deformation west of the
anomaly and frequent earthquakes south of the rift
zone support the earlier concept that the southern
flank is moving seaward owing to forceful diking in
the rift zone. East of the anomaly, however, the dis-
tinct aseismicity of the rift zone suggests that hori-
zontal dilation caused by intrusions is symmetrical
and that no appreciable strains accumulate. The‘net
differential horizontal ground movements on oppo-

 

147

site sides of this suspected fault may resemble those
that develop across transform faults along mid-
oceanic ridges.

GEOCHEMISTRY, MINERALOGY, AND
PETROLOGY

EXPERIMENTAL AND THEORETICAL GEOCHEMISTRY

Neutralization of acid mine water

F. E. Senf‘tle and F. D. Sisler demonstrated by
laboratory experiments that anerobic activity will
neutralize acid mine water. The process is accelerated
by inserting electrodes in the bottom and surface of
the water. Sewage sludge can be used as the nutrient
source, and the process generates some electrical
power and forms elemental sulfur.

Lead isotopes, ore genesis, and ore-prospect evaluation

Lead-isotope analyses of two Kuroko-type ores
(submarine volcanic exhalative) and one epigenetic
ore from Japan, three epigenetic series from Indo-
nesia, and two ores from Peru by M. H. Deleveaux
showed lead compositions that overlap those of open-
ocean pelagic and continental sediments. The iso-
topic composition of these leads does not correspond
with that of ocean—ridge or intraplate volcanic rocks
that represent oceanic mantle. The Tonga-Kermadec
are also has been shown to have oceanic mantle
values (Oversby and Ewart, 1972). Tatsumoto
(1969) has shown that volcanic rocks on the eastern
side of Japan also contain leads characteristic of
pelagic sediments. B. R. Doe and R. E. Zartman, in
attempting to place the lead data into the context
of plate tectonics, demonstrated that submarine ex-
halative ores of Devonian and Triassic age, collected
by W. E. Hall from the Shasta district, have lead-
isotope ratios characteristic of oceanic mantle. Rocks
and ores of Jurassic age and younger in the Shasta
district have lead values similar to those of pelagic
sediments. P. W. Lipman (unpub. data, 1975) sug-
gested that the Devonian and Triassic arc environ-
ment in the Shasta district was a primitive arc simi-
lar to Tonga and Kermadec. The subduction of lithi-
fied pre-Jurassic sediments as proposed by Hamilton
(1969) explains these data. This model suggests that
lithification controls the subduction of sediments.
Lithified sediments are apparently available in ma-
ture island arcs and continental margins but are not
available in primitive island arcs.

148

Thermochemistry of fossil-fuel formation

The thermochemistry of 140 common organic com-
pounds with respect to deoxygenation reactions was
examined by Motoaki Sato. In general, oxygen-rich
compounds of organic remains could transform to
carbon-hydrogen-rich compounds of fossil fuels
through spontaneous decarboxylation and dehydra-
tion reactions, even at room temperature. Given geo-
logic time, fossil fuels could form from buried organic
remains in an ordinary diagenetic environment. High
temperatures would accelerate the rate of transfor-
mation but are not an essential requirement for the
formation of fossil fuels. The transformation reac-
tions are exothermic, so that the process itself could
create abnormal temperature gradients and thus
accelerate itself.

Calorimetric studies

R. A. Robie and B. S. Hemingway determined the
heat capacities of muscovite, pyrophyllite, magnesite,
KAISi3O8 glass, and NaAlSigog glass, measured be-
tween 12 and 385 K, and their standard entropies
determined by means of adiabatic cryogenic calo-
rimetry. The heat capacities of 10W albite, analbite,
sanidine, microcline, magnetite, hematite, muscovite,
pyrophyllite, and periclase were determined by dif-
ferential scanning calorimetry between 300 and 800
K. New values for the enthalpy of formation of kao-
linite, muscovite, low albite, anorthite, and gibbsite
were obtained from heat-of—solution measurements
using HF (aqueous) or the solvent.

Alteration processes in mafic and ultramafic rocks

An experimental evaluation of mineral stability
relations in the system MgO-SiOZ-HZO at elevated
pressures and temperatures has been made by J. J.
Hemley and J. W. Montoya (Anaconda Company)
and P. B. Hostetler and C. L. Christ (USGS). The
activity of silica is the dominant control on geo-
chemical processes in this system and therefore on
processes involving mafic and ultramafic rocks. The
results of this study apply particularly to serpentini—
zation, talc-carbonate alteration such as that associ-
ated with mercury deposits, development of brucite,
retrograde reactions of metalliferous skarns, and the
controls of talc-bearing assemblages in high-grade
metamorphic terrane.

In this type of study, reactions involve both the
fugacity of water and the activity of silica, so that
plots of the intersections of one type of data can
define invariant points of the other. Combined stud-
ies provide more information than simple dehydra-

 

GEOLOGICAL SURVEY RESEARCH 1975

tion studies. Aqueous equilibria studies reach equi-
librium faster than solid-liquid reactions. This study
defines a value of Aszgg for talc of — 5526.8 kJ/mol.

Laser Raman spectroscopy of fluid inclusions

Edwin Roedder (USGS), in a cooperative effort
with G. J. Rosasco (National Bureau of Standards)
and J. H. Simmons (Catholic Univ.) looked into the
feasibility of laser-excited Raman spectroscopy for
nondestructive analysis of specific phases in single
fluid inclusions. The technique uses a low-power He-
He laser for optical alinement; then a powerful
argon laser is focused on the inclusion with micro-
scope optics perpendicular to the first set. Scattering
and fluorescence in this intense illumination (50
MW/cmz) make the beam visible even in gases, so
that it can be directed into the desired phase. Raman
emission (from the given phase only) is detected
with special electronics and processed via several
procedures. A series of special samples was prepared
and run, and, even at this early stage, some fascinat-
ing potentials have been proven. It will not be a
panacea, but its greatest promise is in some other-
wise intractable analytical problems such as SO, in
daughter crystals (and its distinction from sulfide in
solution), C020 vs HCOr1 vs CO.‘2 in solution, or-
ganics in water solution, nitrogen and CO in liquid
C02, and perhaps C‘Z/C” ratios on 10—8-g samples.
Several of these have already been verified by good
peaks on a nice, clean, low-background spectrum
from natural inclusions.

Na-K distribution between hornblende and melt: a possible
geothermometer

R. L. Helz calculated the distribution coefficient
for the reaction:
Na+ (A site of hornblende) +K+ (melt) +
K+ (A site of hornblende) + Na+ (melt) +

for the 24 hornblende-melt pairs obtained by partial
melting of three basalts at PH20=5 kb. The distri-
bution coefficient:

(K/ Na) hornblende
kb =—-——————

(K/Na) melt
shows a well-defined linear variation with tempera-
ture and may be a usable broadgage geothermom-
eter, if the composition of the melt in equilibrium
with a. given hornblende can be determined.

Bulk analysis of thin sections by electron microprobe

Bulk chemical analyses of thin sections by electron
microprobe (US. Geological Survey, 1972, p. 197)
by J. R. Lindsay on sections furnished by G. W. Leo

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

generally supported field relations and petrographic
observations. The thin sections represent a suite of
18 samples including altered diabase, amphibolite,
and calc-silicate hornfels produced by progressive
contact metamorphism and associated with metaso-
matic magnetite deposits in the Samli area of west-
ern Turkey (Leo, 1972). Although some of the analy-
tical values exhibit excessive scatter for petro-
graphically similar rocks, the analyses in general
are acceptable, given the small sample size (2 to 10
mg) and consequent analytical uncertainties. Nor-
mative plots indicate that (1) diabase and amphib-
olite are compositionally related and are similar to
average compositions of basalts and well-studied
orthoamphibolites and (2) calc-silicate hornfels ap-
pears to have been derived in part from amphibolite
and in part from dolomitic limestone, which under-
lies much of the region.

MINERAL STUDIES AND CRYSTAL CHEMISTRY

CRYSTAL CHEMISTRY OF THE SILICATES

Cation distribution in pyroxenes

Two pyroxenes, one a low-calcium pigeonite
(W04.2En40.6F555,2) from a relatively quickly
quenched andesitic pitchstone (Virgo and Ross,
1973) and the other a hypersthene (WomEnm,6
Fsim) from lunar anorthosite 15415 (Stewart and
others, 1972), were studied by H. T. Evans, Jr.,
who used X-ray methods to determine the degree of
ordering of the cations on the M 1 and M2 crystallo-
graphic positions in the crystal structure. For the
Mull pigeonite, least-squares analysis of 861 X-ray
intensities measured with the Picker automatic dif-
fractometer revealed that M 1 position contains
[Mg0,GS(Fe, Mn)0,31Ti0_m] and the M2 position con-
tains [Mg0.13(Fe, Mn)o.7gCa0.os]. This represents a
degree of ordering with respect to iron in M2 of
about 44 percent. Least-squares refinement of 327
X-ray intensities from the lunar hypersthene shows
that the M1 and M2 sites contain (MgofigFeofl) and
(MngFe,UgMnOMCaM.), respectively. This repre-
sents a degree of ordering with respect to iron in
M2 of about 58 percent.

Growth rates of pyroxene exsolution lamellae

J. S. Huebner calculated the time required to
grow augite lamellae in pigeonite by a diffusion-
driven exsolution process. Augite lamellae up to 30
,um thick have been found in low-calcium pyroxenes
in the ancient lunar noritic breccia 77215 as well as
in pyroxenes from many other lunar and terrestrial

 

149

rocks. The growth of lamellae can be described in
terms of Ca-(Mg, Fe) volume diffusion at 800° to
1,150°C.The minimum suggested diffusion rate, ob-
tained by extrapolation to 800°C of data for cal-
cium, magnesium, and iron diffusion in oxides and
silicates, is 10—19 cm2 s—l. The maximum time needed
to enlarge the augite lamellae from a discrete plane
several hundred angstroms thick to 30 ,um thick is
50,000 yr. The presence of such lamellae is not evi-
dence for a longer period of annealing. Thus, We do
not have to assume that the breccia was buried at
great depth so as to maintain high-temperature dif-
fusion processes for millions of years.

MINERALOGIC STUDIES
An index method for mineral identification

R. E. Wilcox demonstrated how indices of refrac-
tion of immersed mineral fragments can be deter-
mined more rapidly and reliably by using disper-
sion coloration effects instead of the conventional
Becke—line effect. The several means for producing
this coloration have been tested extensively; one of
the most practical and easiest to set up in the polariz-
ing microscope is “central focal masking,” in which
a narrow beam of white light is produced by a con-
stricted aperture at the focal point of the substage
lens assembly and blocked by a central opaque dot
at the focal point of the objective. The result is that
the irregularities of the immersed fragment are
sharply imaged on a dark field; they are red or
orange if the immersion liquid is of slightly lower
index, green or blue if the liquid is slightly higher
in index, and a deep violet color if the frag-
ment and liquid have matching indices. This tech-
nique is also useful in the quality control of mineral
separations, where undesired constituents can be
made to stand out in a strongly divergent color by
mounting the sample in an immersion liquid that
has a refractive index closely matching that of the
desired constituent.

VOLCANIC ROCKS AND PROCESSES

HAWAIIAN VOLCANO STUDIES
Summary of 1974 Kilauea activity

Kilauea Volcano exhibited a variety of activity in
1974. The staff of the Hawaiian Volcano Observa-
tory, with D. W. Peterson as Scientist-in-Charge,
observed and recorded the activity, measured the
deformation of the ground, monitored the seismicity,
and conducted related studies. Other professional
members of the observatory staff during the year

150

included R. I. Tilling, C. J. Zablocki, J. D. Unger,
J. P. Lockwood, R. Y. Koyanagi, and E. T. Endo.

From January to June, the vents at Mauna Ulu
overflowed repeatedly, and the lava shield reached
a height of more than 120 m above the pre-1969
ground surface. Much of the lava was erupted dur-
ing well-defined episodes characterized by foun-
tains as high as 70 m and lava flows that traveled as
far as 9 km from the vent. Each episode was ac-
companied by sharp deflation at Kilauea’s summits
monitored by tiltmeters. Between episodes, lava was
generally confined to the immediate vicinity of the
vents, though some quiet overflows occurred. During
these intervening periods, Kilauea’s summit rein-
flated, and the number of shallow earthquakes in
the caldera increased. Beginning in early June, ac-
tivity at Mauna Ulu progressively declined, the sur-
face of the lava column steadily dropped, and re-
peated rockfalls from the vent walls produced a
crater that ultimately measured about 100 m in
diameter. In late July, the lava disappeared below
the rubble-choked floor of the crater, and nearby
seismographs stopped recording harmonic tremor.
Copious fumes were emitted until the end of the
year, but eruptive activity was not renewed.

Brief but spectacular eruptions took place else—
where on.Kilauea on July 19—22, September 19, and
December 31, 1974. The July eruption was located
along fissures in the southern and southeastern parts
of the summit region. Lava covered the floors of
Keanakakoi Crater, Lua Manu Crater, the south-
eastern part of the caldera, and adjacent areas.
About 10><10G m3 of lava was erupted. The Septem-
ber eruption was mostly within Halemaumau and
also along a fissure that extended southwestward
across the caldera floor to the wall. The new lava in
Halemaumau reached a depth of about 19 m be-
fore draining back to leave a new pond about 10 m
deep that completely buried the previously exposed
1968 and 1971 lava. The new lava on the caldera
floor partly buried the flows erupted in September
1971. The eruption lasted 8 h; a total of 10.9><106
m3 of lava was erupted, but, after drainback, about
6.1><10G m3 remained.

The December 31 eruption took place along an
in-place system of fissures between the caldera, the
Koae fault system, and the southwestern rift zone.
Fountains had a maximum height of 100 m, and
flows had a total length of 12 km. During the 6—h
eruption, about 15><106 m3 of lava was erupted. The
eruption was accompanied and followed by a large
deflation of the Kilauea summit region and an in-
tense earthquake swarm along and near the south-

 

GEOLOGICAL SURVEY RESEARCH 1975

western rift zone. Between December 31 and Janu-
ary 5, nearly 200 earthquakes of magnitude 3 (Rich-
ter scale) or stronger were recorded, 5 of which ex-
ceeded magnitude 5.

Mauna Loa Volcano stirs

Mauna Loa Volcano, quiet since 1950, showed pre-
liminary signs of reinflation during 1974. The aver-
age daily count of shallow (0 to 5 km deep) caldera
earthquakes recorded at Mauna Loa’s summit by
the seismic network of the Hawaiian Volcano Ob-
servatory increased abruptly from less than 10 to
several dozen in late April. The annual monitor of
precision-measured geodimeter lines in August re-
vealed significant extension along several lines. To
provide improved surveillance, two new seismic sta-
tions were installed at the summit; and additional
geodimeter lines were established. After a brief
seismic swarm in August, when the earthquake
count one day reached a maximum of 455, the daily
count varied from 40 to 180 until December. From
December 7 to 20, an intense seismic swarm was
centered below the summit caldera; during this time,
the daily earthquake count reached as high as 1,500,
including several that exceeded magnitude 3 and one
that measured 4.5. An emergency reoccupation of
the geodimeter network, with the assistance of a
U.S. Marine helicopter, revealed further significant
extension of lines. After the swarm subsided, the
daily count dropped back to between 30 and 120.

Preliminary locations have been determined for
earthquakes larger than about M =2.5. They general-
ly form an alinement from the summit caldera ex-
tending for a few kilometres down the southeastern
margin of the southwestern rift zone. Focal depths
are generally about 5 km. Scattered fiurries of earth-
quakes also occur beneath the southeastern and
western flanks of the volcano.

Dike intrusion causes rift-zone dilation

Examination by D. A. Swanson, W. A. Duflield,
and R. S. Fiske of triangulation, trilateration, and
leveling data obtained throughout the 20th century
showed that the southern flank of Kilauea was dis-
placed upward and away from the rift zones by as
much as several metres. The amount of horizontal
displacement approximates the probable amount of
dilation that accompanies the intrusion of dikes in
the rift zones and is greatest for periods of most
intense activity, as is evidenced by the frequency of
eruptions. The displacement and seismic events that
take place on the southern flank soon after intrusive
activity indicate that the displacement is the result

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

of forceful intrusion in the rift zones, not the cause
of relatively passive intrusion. In contrast to the
southern flank, seismic and geodetic data indicate
that the northern flank is Virtually immobile, prob-
ably because Kilauea was built on the southern slope
of Mauna Loa and was consequently influenced by
Mauna Loa’s gravitational stress system, which
favors displacement away from the volcanic edifice.
The northern flank is unbuttressed and free to move
away from the edifice when prompted by the force-
ful intrusion of dikes.

The active part of Kilauea’s eastern rift zone has
apparently migrated several kilometres sbuthward
with time, as is shown by the location of recent vents
along the southern edge of the rift zone. The loca-
tion of the axis of a positive gravity anomaly along
the northern edge of the active rift zone also sug-
gests southward migration.

The Hilina fault system is considered to be a
gravity-dominated system not directly related to the
rift zones. Gravitational instability resulting from
uplift and seaward displacement is eventually re-
lieved by normal faulting along the seaward part
of the southern flank. The Hilina faults are thought
to bottom at shallow depth without intersecting
magma reservoirs, except possibly along part of the
lower eastern rift zone, where the fault system im-
pinges upon the rift zone. Strains have been accu-
mulating within the Hilina system throughout this
century, and a high level of instability may have
been reached.

Finite-element analysis of cooling of Alae lava lake

The analysis of the cooling of Alae lava lake,
Hawaii, that was started by D. L. Peck (USGS) in a
cooperative program with J. C. Jaeger (Australian
National Univ.) (US. Geological Survey, 1974, p.
A127) was extended by means of a computer prb-
gram developed by H. R. Shaw and M. S. Hamilton.
The program, which is based on finite-element anal-
ysis, takes into account the cooling by rainfall as
well as the latent heat of the basalt and can use
either a constant or a variable thermal diffusivity
for the lava. The abundant temperature data col-
lected over a 4-yr period from the 15-m-thick ponded
basalt flow can be approximately duplicated by com-
puted temperatures based on a constant diffusivity
for the basalt of 0.006 cmz/s and a latent heat of 80
cal/g. A better match can be achieved by using a
variable diffusivity. The computations indicate that
the thermal conductivity decreases significantly with
increasing vesicularity of the basalt, in agreement
with conclusions by Robertson and Peck (1974)

 

151

based on laboratory measurements; the computa-
tions also indicate that conductivity increases sig-
nificantly with increasing temperature, in agree-
ment with unpublished laboratory studies of sam-
ples from Alae crater by K. Kawada (Univ. of
Tokyo). Cooling by the abundant rainfall, which
averaged 2.50 m/yr, did not substantially decrease
the 1.14-yr time for solidification of the lava lake.
It did, however, drastically decrease the duration of
postsolidification cooling; the total time for cooling
to 100°C, for example, was decreased from 19.6 to
4.0 yr.

Mechanism of formation of pillow lava

Underwater observations and motion pictures
taken by J. G. Moore of growing pillows off the
southern coast of Hawaii demonstrated that pillows
do not grow by stretching of an outer plastic skin,
as is commonly thought. Rather, they expand,
branch, and lengthen as fresh lava inside the pillow
(fed from upslope) distends and cracks the outer
crust. New crust is continuously formed adjacent
to one or more incandescent opening cracks. The
pillow lobe grows sporadically downslope as a given
crack stops spreading and a new one forms more
toward the distal end of the growing pillow tongue.
Hence, most young pillowed lava flows are composed
of a tangled mass of cylindrical interconnected flow
lob-es. Independent discrete sacks are rare.

Fast-spreading cracks (~5 cm/s) are commonly
zigzag in form and produce corrugations perpendi-
cular to the crack. Slow-spreading cracks (~0.1
cm/s) produce smaller fault slivers parallel to and
tilted away from the crack. Ridges of both types
record the history of grthh of the pillow crust;
they account for the parallel ribbed appearance of
fresh pillows in ocean-bottom photographs.

The development of pillow crust adjacent to open-
ing cracks is analogous to sea-floor spreading in
which oceanic lithosphere is form-ed at and diverges
from oceanic spreading ridges. The fault slivers in
pillow crust can be compared with the outward
tilted fault blocks that bound slow-spreading ocean-.
ridge systems.

Age of some Pacific seamounts

Many thousands of seamounts, most the remnants
of extinct volcanoes, particularly those that form
linear chains, can be explained by the eruption of
material from “hotspots” in the mantle onto moving
plates. Most, however, must either form at or near
spreading ridges or be the result of random mid-
plate eruption-s. To test these two hypotheses,

152

G. B. Dalrymple and D. A. Clague dated four sea-
mounts in the north-central Pacific by means of con-
ventional K-Ar and 40Ar/39Ar techniques.

Khachaturian and Rachmaninoff seamounts in the
Musicians seamounts are 65212.6 and 86.6:52
my. old, respectively. A single boulder of rhyolite
dredged from the northern slope of the seamount
beneath Necker Island in the Hawaiian chain has
an age of 77 .6: 1.7 m.y., which suggests that Necker,
previously dated as about 10 my. old, is a compos-
ite seamount constructed of both Cretaceous and
upper Tertiary volcanoes. The minimum age of
Wentworth seamount, which sits atop the Hawaiian
Ridge near Midway, is 71:5 m.y. Like Necker,
Wentworth appears to be another Cretaceous vol-
cano that was subsequently incorporated into the
Hawaiian volcanic chain. The ages of these four Cre-
taceous seamounts, which are equal to or slightly
less than the age of the adjacent sea floor inferred
from extrapolation of magnetic anomalies, indicate
that these seamounts formed at or near the crest of
the East Pacific rise.

“Absolute" plate-motion models based on “hotspots” premature

It has been proposed that linear volcanic chains
on the Pacific plate, of which the Hawaiian chain is
the best known example, were formed by the steady
passage of older Pacific lithosphere over fixed melt—
ing anomalies in the asthenosphere or the deep
mantle, at least during the last 70 to 80 my. It has
further been proposed that the active shield—build-
ing southeastern ends of these chains form part of
a fixed reference frame on Earth from which “abso-
lute” plate motions can be derived. E. D. Jackson,
(1974) however, recently pointed out that age data
on volcanoes of chains in the Pacific are not linear
when plotted against distance along the chains. This
scatter appears to be a result in some cases of the
use of inappropriate age data, in others of dating
lavas of volcanoes whose tholeiitic and alkalic suite
rocks have extended life spans, and in still others of
dating volcanic rocks that represent a period of re-
juvenated volcanism on older shields. However, in
many cases, the scatter is demonstrably the result
of real variable rates of emplacement of volcanic
edifices along chains. The time scale of apparent ir-
regular progression, where documented or suspected,
ranges from 1 or 2 to 30 or 40 my, and the detailed
rate of volcanic progression in the Hawaiian chain
ranges from as little as —7 to as much as +24 c/yr.
On the other hand, students of magnetic anomaly
time scales maintain that spreading rates along

 

GEOLOGICAL SURVEY RESEARCH 1975

oceanic rift systems in the major oceans of the
world, including the Pacific, have been relatively
constant over the last 70 to 80 my. Jackson suggests
at least three major possibilities that may explain
this apparent lack of kinematic agreement: (1) The
rate of volcanic propagation of linear volcanic chains
is not directly proportional to the rate of Pacific
plate motion; (2) the East Pacific rise, While main-
taining a steady spreading rate, has jumped or mi-
grated in an irregular manner with time; or (3) the
magnetic anomaly time scale is not linear. Of these
alternatives, the weight of evidence at present favors
the first, although all three mechanisms may be
involved.

COLUMBIA PLATEAU STUDIES

Linear vent systems and eruption rates of Yakima Basalt

D. A. Swanson, T. L. Wright, and R. L. Helz found
that flows belonging to two sequences of flood basalt
in the Miocene part of the Yakima Basalt, the vast
Roza Member (volume, >1.5X 103 km3) and the less
extensive Ice Harbor flows (velume, <10 kma), were
erupted from linear vent systems tens of kilometres
long and a few kilometres wide. The Roza vent sys-
tem is near the eastern edge of the Columbia Plateau,
and the Ice Harbor system is near the center of the
plateau. The vent systems parallel the trend of the
Chief Joseph dike swarm and are characterized by
remnants of spatter and tufi' cones, local accumula-
tions of thin pahoehoe flow units, bedded pumice, and
dikes. The Roza flows cover vast areas and advanced
many tens of kilometres from their vents. The Ice
Harbor flows are much less extensive and are local-
ized near their vents. Linear vent systems for other
units can be inferred from outcrop patterns, and
such systems may be typical for the Yakima Basalt.
Using the dimensions of the vent systems and the
rheologic model of Shaw and Swanson (1970) , Swan-
son, Wright, and Helz estimate that the Ice Harbor
flows were erupted at rates comparable to those of
Kilauea and Mauna Loa, whereas the Roza flows were
erupted at rates three to four orders of magnitude
higher. The heat energy released during the short-
lived Roza eruptions equals or exceeds the yearly
global energy loss by conducted heat flow. Long-term
rates of production for Yakima magma were com-
parable to rates of production for Hawaiian and Ice-
landic basaltic magma and do not necessarily imply
unusually large concentrations of heat energy in the
mantle.

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

CALDERA STUDIES

Caldera collapse breccia, San Juan Mountains, Colorado

In four large Oligocene calderas in the western
San Juan Mountains—Lake City, Silverton, San
Juan, and Uncompahgre——P. W. Lipman found that
spectacular breccias are intermixed with thick intra
caldera ash—flow tuffs that accumulated during cal-
dera collapse. These breccias are divided into two
intergradational types: mesobreccia, in which num-
erous small clasts are visible within single outcrops,
and megabreccia, in which many clasts are so large
that the fragmental nature of the deposit is obscure
in many individual outcrops.

In general, mesobreccia occurs as thin tabular de-
posits locally interlayered with upper parts of the
intracaldera ash-flow accumulations; it is readily
interpretable as resulting from rockfalls and rock-
slides from the caldera walls. In contrast, the mega-
breccia is the dominant lower part of the caldera-
filling sequence and contains only minor intermixed
ash-flow material. The megabreccia is difficult to dis-
tinguish from possible precollapse caldera floor in
places, but local lenses of welded tuif near the deep-
est exposed stratigraphic levels within the calderas
indicate that these rocks are mostly megabreccia
resulting from slumping and caving of caldera walls
—but on a much greater scale——during the initial
stages of caldera collapse.

Megabreccias similar to those in the western San
Juan calderas occur on other eroded collapse struc-
tures in the Western United States, and the presence
of such deposits may be useful guides to the roots of
caldera structures in deeply eroded, highly altered, or
structurally complex old volcanic terranes.

Megabreccia in Mount Aetna complex, Colorado

Priestley Toulmin III reported that identification
and mapping of megabreccia and fossil landslide de-
posits have permitted more precise delineation of
the outline of the caldera associated with the volcanic
center near Mount Aetna in the southern Sawatch
Range, Colo. Despite the nearly chaotic nature of the
breccia accumulation, a crude internal stratigraphic
succession seems to exist: the lower part of the mass
consists principally of monolithologic breccia derived
from the underlying bedrock, whereas more polymict
breccias and breccias with a significant volcanic com-
ponent are more prominent upward and toward the
interior of the caldera. Such a succession implies that
talus and landslide deposits along the margins of
the depression are progressively overridden by trans-

 

153

ported and volcanogenic materials as the depression
deepens and eruptive activity intensifies.

Age of rhyolite volcanism, Coso Mountains, California

The age and volume of rhyolitic volcanism in the
Coso Mountains geothermal area of southern Cali-
fornia were determined by M. A. Lanphere, G. B.
Dalrymple, and R. L. Smith. The silicic eruptive cen-
ters, which include at least 31 recognizable rhyolite
domes and flows, are distributed within an area of
about 120 kmz. The total volume of erupted rhyolitic
lava is about 2.4 km3. Two basalt flows provide limits
on the age of the rhyolite domes and flows. A basalt
thought to be older than any of the rhyolites on field
evidence has an age of 3.24:0.10 m.y. A basalt that
has an age of 0.038i0.0‘32 m.y. is thought to be
younger than any of the rhyolites. The K-Ar ages
measured on 16 of the domes range from about 0.04:
0.02 to 0.96:0.15 m.y. Most of the units, however,
appear to be between 0.05 and 0.15 my. old. There
is no geographic progression or pattern of ages with-
in the rhyolite dome field.

Volcano-tectonic implications of Glass Mountain and Mono

Craters, California

Close similarities between the petrochemistries
and structural settings of the Glass Mountain rhyo-
lite complex, on the northeastern rim of Long Valley
caldera, and the much younger Mono Craters, north-
east of the caldera, suggested to R. A. Bailey that the
evolution of the former provides information on the
possible future evolution of the latter.

Geologic mapping of Glass Mountain by Bailey has
shown that the lavas are more crystal rich in the
lower part of the complex and that there is an ap-
parent upward progression from early-stage sub-
liquidus rhyolites to late-stage superliquidus rhyo-
lites. Potassium-argon dates of 1.92 m.y. (Bailey and
others, 1976) and 0.9 m.y. (Gilbert and others, 1968)
indicate that this progression developed over a period
of at least 1 m.y. The fact that the eruptive centers
of Glass Mountain are on an arc concentric with the
walls of Long Valley caldera suggests that they are
on an outer caldera ring fracture and represent early
leakage from the Long Valley magma chamber prior
to its evisceration by the eruptions that produced the
Bishop Tuff 0.7 m.y. ago.

R. W. Kistler (1966) has noted that the Mono
Craters also lie on an arcuate ring fracture having
an apparent diameter of 14 km. Additional, more
extensive arcuate fractures and faults mapped by
Bailey indicate that the ring-fracture zone is nearly
18 km in diameter and shows a cumulative down-

154

ward displacement of at least 200 m centripetally.
These structural relations together with (1) the
remarkable chemical homogeneity of the Mono Cra-
ters (Carmichael, 1967), (2) their very cloSe petro-
chemical similarity to the older but structurally
‘analogous rhyolites of Glass Mountain ,( Jack and Car-
michael, 1968; Noble and others, 1972), and (3)
their very young age (31,000 to 1,300 yr (Dalrymple,
1967 ; Friedman, 1968)) imply that the Mono Craters
overlie a large, possibly active magma chamber. A
tentative estimate of the depth to the chamber based
on Carmichael’s (1967) data is 6 to 22 km.

If the evolution of the Mono Craters is similar to
that of Glass Mountain, pumice and ash eruptions
can be expected to continue for several hundred-year
intervals. Conceivably, these eruptions could even-
tually culminate in caldera-forming ash-flow erup-
tions similar to those that produced the Bishop Tuff
and Long Valley caldera, but such an event would
occur far in the future and would undoubtedly be
preceded by abundant forewarning seismic activity.
If the Mono Craters are underlain by an active mag-
ma chamber, it may be a potential source of geo-
thermal energy, provided the “dry—hot-rock” method
of heat extraction can be successfully developed.

PETROLOGIC AND PETROCHEMICAL STUDIES

Laramide magmatism and uranium-thorium fractionation, central

Front Range, Colorado

In a continuing study of the petrology and chemis-
try of the early Laramide intrusions and volcanic
rocks of the central Front Range, Colo., George Phair
discovered that alkalic, alkali-calcic, calc-alkalic, and
calcic, as well as tholeiitic, magma types all occur
within this relatively small region. Recognition of

this marked diversity invalidates earlier studies in‘

which all of the chemical variations were assigned to
a single line of descent.

Phair found that, although the magma types are
closely related in time, they are geographically sep-
arable. N epheline-bearing alkalic rocks occur only in
the extreme north and south of the region. Northeast
of the medial northwest-trending junction Ranch
Breccia Reef, the region is potassic; southwest of
the reef, it is sodic. The potassic province is further
separable into a predominantly alkalic to alkali-calcic
subprovince to the southwest and a predominantly
calc—alkalic to calcic subprovince to the northeast by
the Livingston Breccia Reef, which is in part fol-
lowed by the tholeiitic Iron Dike.

High concentrations of uranium and thorium cor-
relate with high sodium contents in the rocks and

 

GEOLOGICAL SURVEY RESEARCH 1975

reach maximum value in the southwestern sodic
province. Even greater enrichment of these elements
occurs in the later sodic porphyry and calcium-poor
rocks of the region, which is well known for its hy-
drothermal deposits of pitchblende. The relations
strongly suggest that these deposits are the result of
magmatic fractionation of uranium and thorium.

Trace-element variations, Summer Coon Volcano, Colorado

R. A. Zielinski completed a trace-element study of
the Oligocene Summer Coon stratovolcano, eastern
San Juan Mountains, Colo. The rocks range in com~
position from basaltic andesite to rhyolite and have
similar ages. Chondrite-normalized REE patterns are
strongly fractionated in comparison with oceanic-
arc andesite-dacite sequences. Enrichment factors
relative to chondritic abundances are 80 to 120 for
La but less than 10 for Yb and Lu. Small negative
europium anomalies characterize the rhyolites. Al—
kali and alkaline earth elements vary greatly. As
Si02 increases, Ba increases from 900 to 2000 ppm,
Rb increases fro-m 35 to 90 ppm, Sr decreases from
900 to 350 ppm, K/Rb decreases slightly, Ba/Sr in-
creases, U increases from 0.5 to 2.5 ppm, and Th
increases from 2 to 7 ppm. Nickel in the andesites
ranges from 40 to 70 ppm.

The origin of the andesites is interpreted in terms
of nonmodal partial melting of a trace-element-en-
riched garnet-bearing plagioclase—poor source, possi-
bly subducted crust that has converted to eclogite.
Rhyodacite and rhyolite are interpreted as low-
pressure crystal factionation products of andesite, in
which crystallizing phases are hornblende rich in
REE and plagioclase.

Chromite-ulvéspinel solid solution in alkalic basalts

M. H. Beeson reported that a wide variety of oxide
phases showing extensive solid solution among the
various end-members occurs in the basaltic lavas of
the East Molokai Volcano, Hawaii. Some chromite
grains, which occur as microphenocrysts in the
groundmass and also as inclusions in olivine, contain
more than 50 percent CrzOg. Many of those chromite
grains not entirely enclosed in olivine phenocrysts
are continuously zoned from chromite at the core to
ulvospinel at the margins. Continuous solid solu-
tion between chromite and ulvospinel has been re-
ported previously in the tholeiitic lavas of Kilauea
Iki and Makaopuhi and from lunar basalts, but this
report of chromite-ulvospinel solid solution in an
alkalic rock suite appears to be the first.

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

Ultramafic inclusions in basalts

Xenoliths in basalts from the Western United
States consist of magnesian spinel lherzolites in
which at least four types of gabbroic and pyroxene-
rich bands have formed, according to H. G. Wilshire
and S. W. Shervais (1975). Gabbroic bands range
from amphibole-rich olivine gabbro to gabbronorite
and anorthosite. Nonfeldspathic bands include garnet
pyroxenites and spinel pyroxenites of several types,
amphibole-rich pyroxenite, and pure kaersutite. Each
variety of compositional band has both igneous and
metamorphic subtypes, and members of each group
reveal a complex history of crystallization, subsolidus
unmixing, recrystallization, and renewed fusion.
Composite xenoliths show that there is also a broad
sequence of emplacement of the main groups start-
ing with chromium-rich magnesian spinel and gar-
net clinopyroxenites and ending with gabbros. This
history suggests generation of the melts in an active
diapir of upper mantle peridotite.

PLUTONIC ROCKS AND MAGMATIC PROCESSES

Granitic rocks of the southern part of Yosemite National Park,
California

The granitic rocks of the Yosemite Valley, which
were described in the classic report of Calkins
(1930), were restudied by D. L. Peck with emphasis
on their regional extent and interrelations. The El
Capitan Granite forms a ,large pluton that extends
25 km southeast-of the valley and is intruded by
several small masses of the related finer grained
Taft Granite. The younger Bridalveil Granite and
Leaning Tower Quartz Monzonite are in small bod-
ies near the southern wall of the valley. The Sentinel
Granodiorite as mapped by Calkins consists of at
least four distinct granitic units from three plutons;
from east to west near Glacier Point, these plutons
consist of the following: (1) The marginal phase
of the Tuolumne Intrusive Series, (2) the marginal
and core phases of a zoned pluton that is exposed
over a large area in the drainage basin of Yosemite
Creek, north of the valley (Kistler, 1973), and (3)
the marginal phase of a large zoned pluton exposed
along Buena Vista Crest, south of the valley. The
latter pluton and another large zoned pluton cen-
tered on Washb-urn Lake, east of the valley, are both
zoned from tonalite and granodiorite at the margin
to fine-grained granite and granite po-rphyry at the
core and are intermediate in age between the older
El Capitan Granite and the younger Tuolumne In-
trusive Series.

 

155

Mineralogical layering suggests multiple injections of magma in

Lake Owens Mafic Complex, Wyoming

R. S. Houston and J. L. Ridgley reported that the
Lake Owens Mafic Complex of Houston and others
(1968) of southeastern Wyoming can be subdivided
into three and possibly four units that may repre-_
sent separate injections of magma. The lowermost
unit, possibly only the exposed top of a thicker layer,
consists largely of magnetite gabbro containing rela-
tively sodic plagioclase (Angst). Two successively
overlying units are each marked by olivine (F080)
and calcic plagioclase (Anm), as well as by upward
iron enrichment in the olivine, orthopyroxene, and
clinopyroxene and upward enrichment of sodium in
the plagioclase (to An“). The upper part of each
of these two units is magnetite gabbro, similar to
the lowermost unit. Poorly exposed rocks suggest
yet another overlying intrusive unit that is similar
but whose initial olivine is more iron rich and whose
plagioclase is less calcic—a situation that perhaps
suggests fractional crystallization of the source
magma.

Garnet pyroxenites from Sabah, Malaysia

Garnet pyroxenites and corundum-garnet amphib-
olites from the Dent Peninsula of eastern Sabah
(North Borneo) were investigated by B. A. Morgan.
These rocks occur as blocks in a slump b-reccia de-
posit of late Miocene age. The earliest formed min-
erals include pyrope-almandine garnet, tschermaki-
tic augite, pargasite, and rutile. Cumulate textures
are present in two of the six specimens studied. The
earlier fabric has been extensively brecciated and
partly replaced by plagioclase, ilmenite, and a fib-
rous amphibole. The bulk composition and min-
eralogy of these rocks are similar to those of garnet
pyroxenite lenses within ultramafic rocks. Estimated
temperature and pressure for the origin of the
Sabah garnet pyroxenites are 850i150°C and 191-4
kb, respeetively.

Origin of garnets in plutonic rocks, central Sierra Nevada
batholith, California

Garnets, conspicuous though rare constituents of
some plutonic rocks of the Sierra Nevada batholith,
were studied by F. C. W. Dodge and L. C. Calk. The
garnets have two different modes of origin. The less
common almandine garnet probably formed at low
prevailing oxygen pressure, possibly at considerable
depth, during magmatic crystallization, whereas the
more common almandine-spessartite or spessartite
garnets have resulted from the concentration of
manganese relative to iron in highly differentiated

156

melts. Contamination of granitic magmas by argil-
laceous impurities or metamorphism of the plutonic
rocks do not seem to be likely modes of origin for
the Sierra Nevada garnets.

Geochemistry and differentiation of a gabbro-diorite-tonalite-

trondhjemite suite, Finland

Investigation of the Precambrian hornblende
gabbro-biotite diorite~biotite tonalite-trondhjemite
suite of the Uusikaupunki-Kalanti area, southwest-
ern Finland, by J. G. Arth, Fred Barker, Z. E. Peter-
man, Irving Friedman, and G. A. Desborough
showed that this suite with a continuous variation
in SiO2 from about 42 to 74 percent is the most com-
plete trondhjemite suite known. Major and minor
elements, including rare earths and rubidium, stron-
tium, and barium, show consistent variations that
fit a model of origin in which a slightly alkaline
and moderately wet olivine-tholeiite liquid (K20=
0.7 to 0.9 percent and H20=3 to 4 percent) differen-
tiated by first settling out hornblende, then horn-
blende and plagioclase, and lastly hornblende, plagio—
clase, and biotite.

Emplacement and crystallization of the Humbug stock, Colorado

M. A. Kuntz reported that the Humbug stock, a
relatively homogeneous quartz monzonite body in
the Ten Mile Range, 'Colo., was emplaced as a semi-
solid mass of partially crystallized magma; emplace—
ment was achieved in part by faulting along the
margins of the body. A hornblende-rich facies oc—
cupies the central and northern parts of the stock,
and a biotite-rich facies characterizes the western,
southern, and eastern margins. Differences of
quartz, plagioclase, and alkali feldspar between the
two facies are not statistically significant.

Age data so far obtained present a complex and
somewhat confusing picture but may provide useful
information on the cooling history of the body. Po-
tassium~argon ages of biotite (determined by C. E.
Hedge) and fission-track ages of zircon and apatite
(determined by C. W. Naeser) suggest that the stock
crystallized at 41:2 m.y. (on the basis of biotite
ages), cooled relatively slowly to a temperature of
about 300°C at 34:4 m.y. (on the basis of zircon
ages), and reached a temperature of 100°C about
151-5 m.y. ago (on the basis of apatite ages). Al-
ternatively, the apatite ages may reflect a reheating
event about 15 m.y. ago.

Origin of compositionally zoned plutons of the Sierra Nevada
batholith, California

Investigations by P. C. Bateman showed that the
marginal rocks of compositionally zoned plutons of

 

GEOLOGICAL SURVEY RESEARCH 1975

the Sierra Nevada typically contain abundant horn-
blende and biotite but little quartz and little or no
K-feldspar, whereas interior rocks contain abundant
quartz and K-feldspar but little or no hornblende.
Analysis of modal patterns in the light of experi-
mental data shows that such plutons solidified in-
ward by the marginal accretion of crystals. Because
crystallization proceeded with falling temperature,
successively less refractory minerals were available
for marginal accretion. Typical Sierran magmas
were saturate-d in plagioclase, hornblende, and bio-
tite when they reached the present level of exposure
and consisted of both crystals and melt. Most mag-
mas were also saturated in quartz but had been un-
dersaturated earlier. The magmas became saturated
in K-feldspar only after the temperature of the mag-
ma had fallen appreciably below that at the time
of emplacement. K-feldspar megacrysts grew where
K-feldspar was being precipitated faster than crys-
tals were being deposited on the plutons wall or set-
tled downward. In magmas containing little potas-
sium, K-feldspar began to crystallize much later
than quartz, Whereas in magmas moderately rich in
potassium, K-feldspar began to crystallize shortly
after quartz. In the eastern part of the batholith
(White Mountains), where potassium-rich magmas
crystallized to rocks with more K-feldspar than
quartz, K-feldspar probably began to crystallize be-
fore quartz.

Movements of core magmas during solidification
produced discontinuities and concentrically ar-
ranged “nested” plutons. Penetrations of the core
magma through the crystallized carapace produced
plutonic sequences in which the concentric arrange-
ment has been lost.

METAMORPHIC ROCKS AND PROCESSES

Age of amphibolites associated with alpine peridotites in the

Dinaride ophiolite zone, Yugoslavia

M. A. Lanphere and R. G. Coleman (USGS),
Steven Karamata (Univ. of Belgrade), and Jakob
Pamic (Institute for Geological Research, Sarajevo,
Yugoslavia) completed a geochronologic study of
amphibolites associated with two alpine p-eridotite
masses in the Dinaride ophiolite zone of Yugoslavia.
Pargasite from corundum-pargasite amphibolite in-
terlayered with peridotite in the Krivaja-Konjub
and Zlatibor massifs and amphibole from garnet
amphibolite at Zlatibor yielded K-Ar ages of 160 to
170 m.y. The amphibolites and peridotites occur
within a complex sedimentary-volcanic assemblage
that is similar in lithology and tectonic style to the
Franciscan of the Western United States. The am-

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

phibolites are considered products of a Jurassic
metamorphic event that may represent deep-seated
metamorphism initiated by tectonic emplacement of
the Yugoslavia ophiolites into the sedimentary-vol-
canic assemblage. By analogy with California, the
associated alpine peridotites, gabbro, diab-ase, and
basalt can be interpreted as Jurassic oceanic crust
and upper mantle that probably formed with the
ancient Tethyan Sea.

Reassessment of the concept of “burial metamorphism"

Elan Zen made a review of several low-grade
metamorphosed terranes that have been referred to
as altered by “burial metamorphism.” (For example,
see D. S. Coombs, 1961). Burial metamorphic rocks
are mainly of low grade and have been metamor-
phosed without being affected by penetrative defor-
mation, i.e., without development of schistosity.
Many burial metamorphic rocks characteristically
show zeolitic assemblages. Rocks with similar min-
eral assemblages occur in orogenic belts (for ex-
ample, in Silurian-Devonian rocks of New Bruns-
wick, Canada, and in the Helvetian realm of the
western Alps). Experimental data of the phase
equilibria of the typical zeolite minerals laumontite
and analcime give the maximum stability fields for
the metamorphism of these rocks. In nature, other
factors such as additional chemical components and
the condition of P320 less than Pm,“ tend to restrict
the stabilities of these zeolites to lower pressures,
perhaps to no more than 1 to 2 kb. Under such con-
ditions, massive volcanic rocks and graywackes tend
to fail by brittle fracture rather than by developing
penetrative schistosity. Thus, many instances of
burial metamorphism may merely signify metamor-
phism at very shallow depth and low temperatures.

GEOCHEMISTRY OF WATER AND SEDIMENTS

The primary objectives of geochemical studies in
hydrology are (1) to understand the hydrochemical
processes that control the chemical character of
water, (2) to increase understanding of the physics
of the flow system by application of geochemical
principles, and (3) to understand the rates of chemi-
cal reactions and rates of transport of physical and
chemical masses Within the hydrologic system.

Water near an actiye volcano

Water samples were periodically collected by
C. J. Zablocki and R. I. Tilling in 1973 and 1974 from
the top of the fluid column (approximately 488 m
below the surface) in the 1,262-m-deep Kilauea Vol-

 

157

cano in Hawaii. Chemical analyses of these samples
by Zablocki, Tilling, and B. F. Jones indicate that
the waters are mildly saline and are of the sodium
sulfate type and that seawater is not part of the
hydrogeologic regime above the magma reservoir,
as had been previously suggested by some investi-
gators. Chemical and temperature data also indi-
cate measurable dilution effects (lower salinity and
temperature) in a sample collected the day after a
period of high rainfall.

Silica diagenesis

Diagenetic cristobalite is Widely present in the
Monterey Shale of the Templer Range, Calif., and
its d.“1 spacing contracts from 0.411 to 0.404 nm with
increasing depth of burial. Lines of constant d101
spacing, derived by contouring many determinations
of the spacing over a given area, represent virtual-
ly horizontal, isothermal surfaces that prevailed in
the original pile of sediment.

K. J. Murata and R. G. Randall (1975) tested the
possible use of the spacing in structural studies by
X-raying 100 samples of cristobalitic porcelanite
from an area near Taft. They found that the lines
of constant dm. spacings accurately delineated the
folded structure of the Monterey Shale.

Saline environments

Further treatment of previously published data
and 87 new solution analyses from the Lake Magadi
area, Kenya, have extended information on the
chemical evolution of alkaline saline waters. Accord-
ing to B. F. Jones, the dominant influence of evapo-
rative concentration has been documented by con-
stant chloride to sodium and chloride to bro-mine
ratios. The new data also show the loss of fluorine,
boron, and sulfate, as well as alkaline earth, silica,
potassium, and total carbonate during the concen-
tration process. The greatest compositional changes
probably are caused by evaporation to dryness and
only partial re-solution. Calculations suggest that
all water compositions in the Magadi system can be
derived through proportional mixing of dilute in-
flow with lake—surface brines at various stages of
development.

L. N. Plummer (1975) reported that the effect of
mixing seawater or saline subsurface water with
fresh calcium-carbonate type ground water was
evaluated theoretically, by use of the computer pro—
gram, MIX2. The results document the amount of
subsaturation of calcite in mixtures and show the
dependence of the mixing effect on partial pressure
of carbon dioxide, temperature, ionic strength, de-

158

gree of saturation with respect to calcite, and pH
of end-member solutions prior to mixing. The mix-
ing calculations define geochemical environments
that favor (1) development of increased‘porpsity
and permeability in limestone aquifers; and (2)
freshwater dolomitization of calcium carbonate by
replacement.

Gases in ground water'

Methane, propane, and ethane—Partial pressures
of dissolved gases were determined for 17 samples
of ground water from major aquifers of the north-
ern Great Plains. These include samples from sev-
eral members of the coal-rich Fort Union Forma-
tion and from underlying Cretaceous aquifers.

D. W. Fisher and M. G. Croft found that nitrogen
to argon concentration ratio-s in these waters ex-
ceed the calculated value for air-saturated recharge.
The increased ratios probably result from release of
nitrogen during the course of degradation of or-
ganic matter in the formations. Nitrogen and argon
pressures determined for two samples from flowing
artesian wells were substantially lower than the cor-
responding calculated values for lair-saturated re-
charge water. However, methane partial pressure
in each of these waters was greater than 100,000 Pa.
Apparently rapid evolution of methane from the dis-
charging Wells has stripped some of the dissolved
air gases from the formation. This stripping effect
was not evident in other water samples, although
two of them contained methane at comparably high
pressures. '

The range of methane pressures determined was
from about 500 Pa to more than 200,000 Pa; all of
the high values were for samples from the deeper
Cretaceous aquifers. Three of these waters con-
. tained measurable quantities of ethane, and one
sample from a 190-m deep well had a detectable pro-
pane content. Sulfate concentrations were less than
150 mg/l in all samples with more than 10,000 Pa
methane pressure; however, the inverse correlation
is not regular. In contrast, sulfate in shallow Fort
Union water often exceeds 600 mg/l, whereas ob-
served methane pressures in the uppermost aquifers
are less than 5,000 Pa.

Ammonia—Although ammonia, as N, is barely
detectable in most ground water pumped in the Gen-

tral Platte Natural Resources District, Nebr., sig-*

nificant concentrations evidently percolate to the
ground-water reservoir. L. R. Petri and R. A. Eng-
berg reported that ammonia concentrations ranging
from 0.64 to 3.9 mg/l were detected in the upper

 

GEOLOGICAL SURVEY RESEARCH 1975

30 cm of ground water at 10 study sites in late
winter or early spring of 1974.

The ammonia that reaches the water table evi-
dently is oxidized to nitrate at rates that depend
somevx hat on soil permeability. Where soil perme-
ability is high, concentrations in the upper 30 cm
of the ground-water reservoir gradually diminished
only slightly from spring to summer and persisted
throughout the year.

Carbon dioxide—The hydrogeochemistry of Ber-
muda ground water was studied by L. N. Plummer
(USGS), H. L. Vacher (Washington State Univ.),
F. T. MacKenzie (Northwestern Univ.), 0. P.
Bricker (The Johns Hopkins Univ.), and L. S. Land
(Univ. of Texas) in order to clarify the chemical
processes active during phreatic di'agenesis of Pleis-
tocene carbonate sediments. The three processes that
control the chemistry of Bermuda ground water are
( 1) generation of elevated CO2 partial pressures in
soils and marshes, (2) dissolution of metastable car-
bonate minerals (principally aragonite), and (3)
mixing with seawater. 'Nonequilibrium dissolution
and precipitation reactions coupled with seasonally
variable fluxes of CO2 to and from the ground water
are important in accounting for the carbonate min-
eral formation.

Kinetics of calcite solution

L. N. Plummer followed the dissolution of Iceland
spar in COZ-saturated solutions at 25°C and 101,325
Pa total pressure by measurement of pH as a func-
tion of time. Surface concentrations of reactant and
product species were calculated from bulk-fluid data
using mass-transport theory and are near bulk-solu-
tion values, demonstrating that calcite dissolution
under the experimental conditions is controlled by

-the kinetics of surface reaction. An empirical-rate

relationship was developed and applied to predicting
the rate of calcite dissolution in natural environ-
ments.

STATISTICAL GEOCHEMISTRY AND PETROLOGY

Q-mode factor analysis

Continuing investigations by A. T. Miesch of the
application of an extended form of Q-mode factor
analysis to problems in geochemistry and petrology
led to the concept of compositional structure in
igneous rock bodies. The compositional structure of
a body is reflected by the quasi-rank of a represen-
tative matrix of chemical or mineralogic data. The
quasi-rank of the data matrix is low, and the com-
positional structure of the body- is simple, if the

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

matrix is similar to a matrix of low true rank. Use
of this method means that the major features of
compositional variation and covariation in the body
can be explained by the mixing or unmixing of rela-
tively few end-members; that is, the igneous body
probably formed by a relatively simple combination
of processes. Simple compositional structures have
been found in (1) a rhyolite—basalt complex in Yel-
lowstone National Park, Wyo., (2) lavas and pu-
mices from the 1959 summit eruption at Kilauea,
Hawaii, and (3) granitic batholiths of the Sierra
Nevada, Calif., and the Alaska-Aleutian Range.

Complex compositional structures occur in rock
bodies that acquired their compositional variation
largely by complex combinations of processes, such
as those that operate in magmatic differentiations.
Complex structures have been identified in several
igneous bodies, including the Pikes Peak batholith
in Colorado, a recent basalt flow in New Mexico,
and the layered series of the Skaergaard intrusion,
Greenland.

Some of the above investigations and the methods
used were described-.by Miesch (1975a, b), and a
computer program was published by Klovan and
Miesch (1975).

Whether the compositional structure of the igne-
ous body is simple or complex, petrologic models
can be developed by searching for end-member com-
positions. Commonly, the end-member compositions
are those of mineral species within compositional
systems such as albite-anorthite, forsterite-fayalite,
or wollastonite-enstatite—ferrosilite. The end-mem-
ber compositions may also be those of mineral clus-
ters such as, for example, those in the system quartz-
orthoclase-albite-anorthite. Compositions within
two-, three-, or four-component systems can be
systematically examined for compatibility with the
compositional variation in an igneous body by using
a new computer program, QSCAN, and compatible
species may constitute end-members for petrologic
models. Commonly, QSCAN identifies mineral spe-
cies actually present in the igneous body, as deter-
mined by conventional petrologic methods. In other
applications, QSCAN has pointed to compositions
of minerals that may have been early differentiates
or of materials that might have been incorporated
into the primary magmas.

Simulation of sampling problems

A new interactive computer program, SAMPLE,
was prepared by A. T. Miesch for the simulation of
sampling problems encountered in either geochemi-
cal exploration or general geochemical surveys. The

 

159

purpose of the program is to observe the effects of
random errors in sampling and analysis on efforts
to detect geochemical anomalies or regional trends.
The results are providing guidelines for judging the
required sampling density and analytical precision
for sampling programs.

Geochemical discriminant for sandstones

J. J. Connor and N. M. Denson reported that sam-
ples of sandstone near the Fort Union-Wasatch con-
tact in the Powder River Basin have been success—
fully assigned to their respective stratigraphic posi-
tion by using a discriminant function based on bulk
chemical composition. The following discrimination
index has correctly classified 81 of 99 sandstone
samples collected near the Fort.Union-Wasatch con-
tact around its outcrop belt:

Z = 2.38 log Fe + 2.09 log Mn + 4.29 log Ba
+ 0.89 log Na

A sandstone sample can be classified if its bulk con-
centrations of iron and sodium (in percent) and
manganese and barium (in parts per million) are
knOwn. Any sample having an index (Z) above 14.92
is assigned to the Wasatch Formation, and any sam-
ple with an index less than 14.92 is assigned to the
Fort Union Formation. This index correctly classi-
fied 26 of 27 samples that were not used to define
the index. The samples were collected from the
Wasatch Formation near the contact with the Fort
Union in northern Campbell County, Wyo. Three
sandstone samples from the lower part of the Fort
Union and four more from the underlying Lance
Formation were tested bythe discriminator and
found to be chemically similar to the Wasatch. All
of these results support previous work (Denson and
Pipiringos, 1969) based on heavy mineral suites and
confirm the suspicion that sandstones in the upper
part of the Fort Union Formation are distinct from
those in the lower part of the Wasatch Formation,
the Tullock Member of the Fort Union, and the
Lance Formation.

ISOTOPE AND NUCLEAR GEOCHEMISTRY

ISOTOPE TRACER STUDIES

Source and history of island-arc magmas

Samples from the basalt, andesite, dacite, and
rhyolite suites of Rabaul and Talasea, New Britain,
were studied for rare-earth content by J. G. Arth
and for strontium isotopic composition by Z. E.
Peterman. The 878r/“Sr ratios in both suites are

160

nearly constant, averaging 0.7037 for Rabaul and
0.7035 for Talasea. The chondrite-normalized rare-
earth patterns for both suites are relatively flat and
show increasing concentrations from basalt to da-

cite. Europium anomalies are not found in pheno- '

cryst-poor basalt and are increasingly negative from
basaltic andesite to rhyolite. The data are compati-
ble with a model for the origin of the basaltic mag-
mas by 20 to 30 percent melting of mantle perido—
tite and a model for the origin of the basaltic ande—
sites, andesites, dacitevs, and rhyolites by fractional
crystallization of olivine, pyroxene, plagioclase, and
Opaques in varying proportions from the basalt
magmas. The trace-element and isotopic character-
istics of both suites are not consistent With an origin
by melting of subducted oceanic crust.

Genesis of Boulder Creek Granodiorite

A study of regional variations in the trace-element
and strontium isotopic composition of granodiorites
of Boulder Creek age (1.7 by.) in Colorado was
started by C. E. Hedge. Thus far, samples from cen-
tral Colorado have higher rubidium, strontium, and
barium contents and more fractionated rare-earth
patterns than samples to the north and south. The
differences are thought to reflect differences in
source materials and genetic processes. Tentatively
identified processes include anatexis of amphibolite
and metagraywacke and fractional crystallization of
mantle-derived mafic magma. The inferred processes
are distinct from those that could be expected in
any simple Cenozoic tectonic analog. Any tectonic
model must explain the generation of large volumes
of magma over a broad area and within a brief span
of geologic time.

A two-stage model for terrestrial lead-isotope evolution

J. S. Stacey proposed a two-stage model for ter-
restrial lead-isotope evolution. This construct utilizes
the solar system age of 4.57 by. and the composi-
tion of primordial lead determined by Mitsunobu
Tatsumoto, along with the recently determined
values for the half-lives of uranium. The model al-
lows the ages of many “volcanic exhalative” lead-
ore deposits to be approximated by their lead-iso-
topic composition to within i 50 my of their known
age by other methods.

Lead-isotopic composition in basalts and sediments from the
Nazca Plate

Lead-isotopic compositions and uranium, thorium,

and lead concentrations have been determined by
Mitsunobu Tatsumoto and Dan Unruh in 11 basalt
and 3 sediment samples from leg 34 of the DSDP.

 

GEOLOGICAL SURVEY RESEARCH 1975

The 232Th/238U ratios and the lead-isotopic composi-
tion of the basalts are typical of oceanic tholeiites
and suggest that the magmas were extruded at the
extinct Galapagos rise. Lead-isotopic compositions,
when corrected for in-place uranium decay, are simi-
lar for all basalt samples analyzed. The similarity
suggests that the magmas originated either from a ‘
portion of the mantle in which lead-isotopic compo-
sition is homogeneous or from one in which partial
melts from different sources have been mixed in the
same proportions for the last 45 my

The lead concentration in a sample of Pliocene
sediment is about average for deep-sea sediments
but about 10 to 20 times higher than that of samples
of lower and middle Miocene sediments. The low
lead concentration in the Miocene sediments can be
attributed to carbonate accumulation. The similarity
of the lead-isotopic compositions in sediments and
basalts supports a hypothesis that the metallic ele-
ments in the metalliferous sediments of the Nazca
plate are of ocean-ridge origin.

STABLE ISOTOPES

Berridale batholith, Australia

Two contrasting types of Paleozoic granitoids oc-
cur widely in southeastern Australia and can gen-
erally be distinguished by their chemistry, min-
eralogy, field occurrence, and initial strontium iso-
tope ratios. Previous work has shown that the
granitoids are derived by partial melting of two dif—
ferent types of source materials: (1) Igneous or “I
type” and (2) sedimentary or “S type.”

J. R. O’Neil (USGS) and B. W. Chappell (Aus-
tralian National Univ.) measured oxygen and hy-
drogen isotope compositions on 59 whole-rock sam-
ples of fresh and altered granitoids and xenoliths.
For S-type plutons, average 3018 values range from
9.9 to 10.5, whereas for the I types the range is 7.9
to 9.4. Xenoliths are about 1 per mil lighter in
O18 and generally heavier in deuterium than the
host rocks. The average 3D values (and water con-
tents) are ~62i4 (1.10 percent) and —77:12
(—0.73 percent) for S and I granitoids, respectively.
Individual 8D values range fro-m —52 to ——108 and
correlate very well with water content: the more
water-rich the melt, the greater the deuterium con-
tent. This effect must be related to the physical and
chemical conditions of the ascent and crystallization
history of the granitoids.

The rather large AO18 (quartz-biotite) values
range from 5.0 to 6.9 (independent of type) with
a mean of 6.0. Thus, typical isotope temperatures

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

of ~520°C are inferred and may be retrograde ef-
fects.

O”Z compositions of trondhjemites

Fred Barker, Irving Friedman, and J. D. Gleason
analyzed the O18 composition of whole-rock samples
of 75 Precambrian and Phan‘erozoic trondhjemites
and acidic metavolcanic gneisses of 19 cogenetic
mafic to intermediate rocks from North America,
Eennoscandia, and southern Africa. Trondhjemites,
metadacites, and metarhyodacites (average contents
of 72.2 percent SiO2 and 1.93 percent K20) that
probably are isotopically undisturbed give an aver-
age 8018 of +7.2 per mi] and a range of +5.5 to 8.3.
The mafic to intermediate rocks show a wide range
of values, the extremes of which indicate exchange
during or after emplacement with either isotopically
light meteoric waters or isotopically heavy wall
rocks but which in part show relatively undisturbed
8018 values of +4.5 to 5.5 per mil. The 3018 values
of the trondhjemites and compositionally similar
metavolcanic rocks, which are definitely lower than
those of most granites and quartz monzonites, are
in accord with the several models of derivation of
these rocks from basaltic parents by partial melting
or igneous differentiation.

Fossil thermal gradients in the Ruby Mountains

The K-Ar and Rb-Sr mineral ages in crystalline
rocks in the northern Ruby Mountains, Nev., are
less than’the ages of the host rocks. Oxygen and
hydrogen isotopic compositions of all the dated min-
erals and quartz have been determined.

R. W. Kistler and J. R. O’Neil interpreted the re-
duced mineral ages to reflect cooling during uplift,
along an arch of regional extent with a trend of
about N. 30° E., that began during emplacement of
the 36—m.y.-old Harrison Pass pluton into the central
part of the range.

Petrologic data indicate that the exposed crystal-
line terrane was at depths that ranged from about
13 to 8 km prior to uplift and erosion 36 my. ago.
Temperatures from top to bottom in this depth in-
terval at the beginning of uplift are estimated to
have ranged from 350° to 560°C on the basis of the
critical temperatures required to permit complete
retention of radiogenic daughter products in the
minerals dated. Oxygen isotope geothermometry in-
dicates oxygen equilibration temperatures that
ranged from 400° to 650°C from top to bottom of
the same depth interval. The thermal gradient in-
dicated by the oxygen isotopic data closely approxi-
mates the thermal gradient that must have existed

 

161

during Mesozoic amphibolite-facies metamorphism
of the crystalline terrane.

Magmatic or meteoric water in are fluids

Studies by R. 0. Rye (USGS) , G. P. Landis (Univ.
of New Mexico), and F. J. Sawkins (Univ. of Min-
nesota) on the hydrogen and oxygen isotopic com-
position of numerous Tertiary hydrothermal ore de-
posits in the Andes of South America indicated that
magmatic fluids are nearly always present at some
stage during the history of the hydrothermal fluids.
The hydrothermal fluids in these Tertiary ore de-
posits are probably not dominated by meteoric
waters, as are those in similar deposits in the West-
ern United States, because of the relatively dry
climate in the Andes during ore deposition. The
study suggests that the dominance of meteoric water
in the hydrothermal fluids of certain ore deposits
may be related to local climate and hydrology rather
than to anything fundamental about ore deposition.

Copper Canyon deposit

J. N. Batchelder found that the fluid-inclusion
water in quartz from the Copper Canyon deposit at
Battle Mountain, Nev., has 8D values that range
from —101.5 to —75.6 per mi]. The calculated 8018
of water from quartz ranged from +3.1 to 10.9 per
mi]. The calculated 8D for water (from biotite anal-
yses) ranged from —71.2 to ~111.5 per mil, and
the calculated 8018 of water from biotite ranged
from +0.5 to +5.0 per mil. These data indicate
that the ore-forming solutions were most likely com-
posed of magmatic water mixed with significant
amounts of meteoric water.

Antarctic climates

Irving Friedman and G. I. Smith showed that
CaClg-6H20 (antarcticite) grown at —20° to —30°C
is enriched in O13 by 11.3 per mil and deplete-d in
D by 16 per mil relative to the solution.

With this information, it is possible to explain the
anomalous isotopic composition of the brines of Don
Juan Pond, Victoria Land, Antarctica. It is also
possible to explain the brine composition in nearby
Lake Vanda and to decipher the climatic history of
this interesting warm lake located 528 km from the
South Pole as follows: (1) Fjord formed 75 my
ago during warm Antarctic climate; (2) fjord
blocked, trapping sea water ~50,000 yr ago; (3)
sea water evaporated, climate cooler than present,
desiccation yielded CaClg-6H20 crystals, winds blew
NaCl and MgCl2 away; (4) brief climatic warming
occurred 2600:200 yr ago, climate slightly warmer

162

than present; (5) climate cooled and lake desiccated
again; (6) another climatic warming occurred about
1,000 yr ago, initial warming slightly warmer than
at present.

The present high temperature (25° to 28°C) in
the lower part of this saline lake is due to solar heat-
ing, not geothermal heating.

Climate and deuterium in tree rings

Irving Friedman made deuterium analyses of
wood (tree rings) from bristlecone pine collected
from the White Mountains, California-Nevada. The
variation in 8D appears to correlate with the Euro-
pean climate from 200 AD. to 1950. There are some
specific points that do not show an exact correlation,
and this discovery may be important to theories of
‘ climatic change. Additional work is now underway
on living trees to determine the relationship between
the SD of tree wood and known climatic factors.

Growth of oats in light water

While growing oats from seeds in closed jars, Irv-
ing Friedman and J. D. Gleason observed that seeds
growing in water from the Antarctic and depleted
in O18 and deuterium grew much more rapidly than
seeds growing in water of more normal isotopic
composition. This observation was confirmed in sev-
eral sets of experiments conducted at different tem-
peratures.

ADVANCES IN GEO-CHRONOMETRY

Thermoluminescence dating technique for Hawaiian basalts

A technique for dating young Hawaiian basalts
using thermoluminescence (TL) was developed by
R. J. May. The basic method, which has been used

for radiation dosimetry in health physics and for‘

age measurements in archeologic studies, depends on
the measurement of a very small amount of light
emitted when dielectric crystals are heated in the
laboratory. The amount of light given off by a sam-
ple is a function of the age of the sample, the natural
radiation dose rate, and the “sensitivity” of the
crystals.

The ages of alkalic basalts from the island of
Hawaii can be reproduced to within about :10 per-
cent when they are compared with carbon-14 and
K-Ar ages on the same lavas. The TL ages on tho-
]eiitic basalts are less accurate, primarily because
low elemental concentrations of uranium and thor-
ium make~these two important sources of natural
radiation difficult to measure. The method, which
appears to have a range of from about 5><103 to

 

GEOLOGICAL SURVEY RESEARCH 1975

5><105 yr, fills an important gap between the useful
ranges of the carbon-14 and the K-Ar dating tech-
niques and should be applicable to other igneous
rock types.

Uranium-lead ages and open-system behavior of pitchblendes,

Shirley Basin, Wyoming

Uranium-lead isotope apparent ages of several
pitchblende and pitchblende-pyrite samples from
roll-type uranium deposits of the Shirley Basin dis-
trict, Wyo., were determined by K. R. Ludwig, and
all have been found to be moderately to very strong-
ly discordant. The discordance and variability of ap-
parent ages, even from clearly cogenetic and closely
spaced samples, show that isolated uranium-lead
analyses of roll-type pitchblende samples can be mis-
leading. The pitchblende samples haVe lost both lead
(greater than 40 percent for some samples) and
238U intermediate daughters such as 2”Rn or 226Ra
(greater than 65 percent for some samples). In-
corporation of an old radio-genie lead component by
the pitchblende has not significantly altered the ap-
parent ages. The oldest apparent ages, which are
the least discordant, indicate that some of the ura-
nium mineralization in the district began earlier
than 34 my. ago.

Age of disseminated uraninite, Wheeler Basin, Colorado

K. R. Ludwig determined the isotopic ages of spe-
cimens, collected by E. J. Young, from the dissemi-
nated uraninite occurrence at Wheeler Basin, Grand
County, Colo. Uranium and lead isotopic analyses
of monazite and uraninite indicate that these min-
erals formed 1,446i20 m.y. ago. This time correlates
well with the intrusion of the Silver Plume Granite.
The uraninite and monazite were also affected by a
later disturbance at 8801-130 m.y. but show essen-
tially no effects of subsequent events. This second-
ary disturbance may have been due to intrusion of
dikes related to the Pikes Peak batholith, dated at
1,041 i 13 my. ago.

Problems in dating sericite

Potassium-argon dating of sericite, a common
wall-rock alteration mineral in epithermal ore de-
posits, has been used to date alteration associated
with mineralization. M. L. Silberman found, how-
ever, that the K-Ar ages of sericite may be anomal-
ously high in host rocks that have a detrital mica
component.

In two Nevada epithermal mineral deposits, seri-
cite has yielded strongly anomalous ages of minerali-

zation. In both cases, it is possible to establish limits

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

for the age of mineralization from geologic field re-
lationships. In both cases, sedimentary rocks, in
which mica occurred as a detrital component, were
the host rocks.

Fluid-inclusion filling temperatures indicate that
temperatures of 200° to 300°C are reached in hydro-
thermal fluids in epithermal ore deposits. Evidently,
these temperatures are not high enough or do not
persist for long enough time periods to release all
prealteration radiogenic argon from muscovite dur-
ing a typical hydrothermal event, despite severe al-
teration of the host rocks.

Dating early Pleistocene men by the uranium-series method

B. J. Szabo (USGS) dated fossil bones associated
with several Neanderthal man discoveries by means
of the uranium-series method. K. P. Oakley (British,
Museum), supplied a tooth at Elephas Atlanticus
that was associated with remains of the Ternitine
man of Algeria. The tooth yielded a Th230 age of
210,000-135,000 yr. Correction for a small amount of
excess Pa231 would indicate an open-system age of
180,000-140,000 yr.

Bone samples from several Neanderthal man 10-
calities in Great Britain were furnished by D. Col-
lins (University of London). The Swanscombe man
was apparently reliably dated at 300,000 yr, but
samples from the Stutton and Brunden localities
yielded only open~system ages of 125,000:20,000
and 174,000:30,000 yr, respectively.

Geochronology in Indonesia

Some 35 samples from Indonesia, dominantly
from Sulawasi and Sumatra, were dated by J. D.
Obradovich in cooperation with P. W. Richards,
W. H. Nelson, and the late D. E. Wolco-tt. The work
on Sulawasi (formerly Celebes Island) has been re-
stricted to the southwestern arm where basaltic vol-
canism commenced on a pre—Cretaceous basement
17 to 18 m.y. ago. This activity was followed by a
period of voluminous andesitic volcanism 9 m.y. ago
and lesser amounts of dacitic eruptions 4 to 5 m.y.
ago. Andesites that appear to be of Holocene age
occur at the southernmost end of the southwestern
arm. Plutonic activity (dioritic to granitic) spans
a period of some 9 to 10 m.y. from ~14 to 5 m.y.
ago. The largest exposed granitic body near Mad-
jene was dated at 6.2 m.y. However, one of the few
shows of mineralization in this region is associated
with a nearby but much smaller and younger body
dated at 5.5 m.y.

Sampling in the northern part of Sumatra was re-
stricted primarily to the numerous granites that

 

163

crop out along the western margin, although a few
samples of upper Cenozoic andesites and tufl’s were
collected.

The oldest granite found so far is from a small
outcrop exposed along the easternmost fault bound-
ary of Lake Singkarak. The K-Ar age of ~290
m.y. on muscovite must be considered simply a mini-
mum, since the granite shows east-west segregation
bands and north—south fracture system. Although
other Sumatran granites have been reported to be
of Permian and Carboniferous age or older, this geo-
chronometric confirmation is the first.

Two large granitic masses, one at and to the east

of Sibolga and the other east of Sisawah, indicate
a period of Triassic plutonism ~210 to 215 m.y.
ago. , .
Late Triassic-earliest Jurassic plutonism (~190
m.y. ago) is indicated just to the east of Kutanopan.
The pluton to the east of Singaimas (northeast of
Lake Singkarak) was emplaced in the latest Jurassic
(~145 m.y. ago). '

The Lassi Granite (southeast of Lake:.Singkarak)
may be another of latest Jurassic or earliest Cre-
taceous age; however, the large analytical uncer-
tainty of its age currently precludes any definitive
statement. The same can be said for the large granite
mass ~25 km to the southeast of Sawahlun-to. Pre-
liminary data indicate a possible age range of 110
to 155 m.y.

A small granite body of middle Cretaceous age
(105 m.y.) north of Kutanopan seems to be the
youngest intrusive mass along the western margin
except for a granite ~11 km south of Padangpand-
jang, which yields an age of ~8 m.y. However, this
granite body sits in the midst of the young andesitic
volcanic field, and the age of 8 m.y. may reflect ther-
mal resetting. The geologic constraints of the post-
Permian and pre-Late Cenozoic do little to solve
this problem.

Two of the upper Cenozoic andesites, one south
of Solok and the other from the caldera rim around
Lake Manindjau, were dated at 1.66 and 0.80 m.y.,
respectively. The age of 0.80:0.20 m.y. places a '
lower limit on the age of the nearby but demonstrab-
ly younger andesitic volcanoes of Singgalang, Tandi-
kat, and Marapi. Although Tandikat and Marapi
have a record of historic eruption, only Marapi has
active fumaroles.

Uranium-series dating of marine deposits

Recent drilling and trenching by the Department
of Defense on Eniwetok Atoll provided excellent
samples of coral for dating by the uranium-series

164

method. Four samples from two cores, supplied by
J. I. Tracey, Jr., were dated by B. J. Szabo. Three
and possibly five unconformities are recognized in
these cores. These unconformities are related to
periods of coral growth during the warm cycle and
higher sea level of the interglacial period, which
was followed by a lowering of the sea level at the on-
set of glaciation and subsequent erosion of the upper
surfare of the reefs.

A sample taken from hole PAR-16 at a depth of
7.9 Hi, just above the upper unconformity, has a Th2’30
date of 8,700i500 yr, which appears reliable be-
cause the Um/U238 ratio of 1.14:0.01 is concordant
for that age. A second sample from that hole taken
at a depth of 9.9 In, just below the upper uncon-
formity, yielded an age of 130,000i7,000 yr. A sam-
ple from hole PAR-15 at a depth of 14.9 m, between
the upper and next lower unconformity, also has an
age of 130,000i7,000 yr. The Um/U238 ratios of
1.12:0.01 and 1.10:0.01 indicate that these sam-
ples remained closed with respect to uranium and
thorium isotopes and that these ages are reliable.

These data show that a hiatus in coral growth of
about 120,000 yr duration can be observed because,
during that time, the level of the ocean did not rise
enough to submerge the reefs and allow coral
growth. If it is assumed that there was no unac-
countable uplift during this interval, these dates
define the last major glacial period in this region
of the Pacific, which occurred from about 130,000
to 9,000 yr ago.

An additional sample from hole PAR-15 at a depth
of 38.7 In, just below the third or possibly the fourth
unconformity, did not yield suitable age results. The
sample apparently underwent both dissolution of
some aragonitic structure and calcitic infilling. The
Th230 date of 165,000 yr can be considered only as a
minimum age; the age calculated from the meas-
ured U“’3“‘/U238 ratio (1.04:0.01) of 460,000:100,—
000 yr can be considered as a maximum.

Five coral and five shell samples from the Fal-
muth Formation of Jamaica have been dated; the
samples were collected from three localities by W.
Moore (US. Naval Oceanographic Ofiice) along the
north shore of Jamaica. The marine terrace is dis-
tinct, with an elevation above sea level up to 10 m.
Only one of the corals yielded concordant Th230 and
Pa231 dates of 129,000-110,000 yr. For the other four
corals, open-system dates were calculated. The aver-
age of the five dates, 130,000:7,000 yr, appears to
be a reliable age for the Falmuth Formation of
Jamaica. Two of the shell samples yielded concord-
ant dates (but ages that were too young) of 70,000

 

GEOLOGICAL SURVEY RESEARCH 1975

and 95,000 yr, respectively; however, these results
do not agree with the dates for the coral samples.
One shell yielded an open-system date of 137,000:
20,000 yr that is in agreement with the average date
of corals. The other two shell samples showed evi-
dence of extensive migration of uranium isotopes
and their long-lived daughter elements; thus, no
ages could be calculated for these samples.

Uranium-series dating of fossil shells and bone
was completed on material supplied by L. M. Gard, Jr.
The results yielded an average age of 127 ,000:8,000
yr for the fos-siliferous deposit of the South Bight II
marine transgression at Amchitka Island in the
Aleutian Islands. These Pleistocene beds were de-
posited during an interglacial high-sea stand con-
temporaneous with the well-dated period of coral
reef formation on Hawaii and Barbados about 125,-
000 yr ago and with our more recent dates of about
130,000 yr for coral reef formation on Jamaica and
Eniwetok.

GEOTHERMAL SYSTEMS

Magma beneath Yellowstone National Park

Geophysical andgeological data gathered by the
USGS over the past 10 yr confirm the 1911 hypoth-
esis of R. A. Daly that a body of magma lies at
moderately shallow depth beneath Yeliowstone Na-
tional Park (Eaton and others, 1975).

The Yellowstone Plateau volcanic field is less than
2 my. old, lies in a region of intense tectonic and
hydrothermal activity, and probably has the poten-
tial for further volcanic activity. The youngest of
three volcanic cycles climaxed 600,000 yr ago with
an immense ash-flow eruption and the collapse of
two contiguous cauldron blocks. Intracaldera dom-
ing 150,000 yr ago, voluminous rhyolite extrusion as
recently as 70,000 yr ago, and the present-day high
convective heat flow suggest a new magmatic in-
surgence.

The existence beneath the Quaternary rhyolite
plateau of a body composed at least partly of magma
is supported by the following evidence: (1) A major
gravity low with steep bounding gradients, (2) an
aeromagnetic low possibly indicating the existence
of material above the Curie temperature at shallow
depth, (3) substantial delays in the P velocity of
seismic waves passing beneath the plateau, and (4)
minor seismicity within the caldera, compared to a
high level of seismic activity in some adjacent areas.
The gravity low that extends beneath a postglacial
arcuate fault zone just northeast of the Yellowstone

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

caldera suggests that the magma extends under the
Tertiary 'volcanic rocks in that area.

Origin of spring and geyser vents in Yellowstone National Park

G. D. Marler and D. E. White completed a report
on Seismic Geyser and its bearing on the origin and
evolution of geysers and hot springs in Yellowstone
Park. Seismic started as a fracture resulting from
the Hebgen Lake earthquake of August 17, 1959.
Over the next 5 yr, the fracture evolved through the
progressive stages of a new fumarole, a small
spouter, then a small geyser, and finally a large
geyser erupting to 15 m in height. Its channel in
the meantime had evolved from a narrow crack to a
vent 12 m in diameter and with a probed (mini-
mum) depth of 6.4 m.

The formation and evolution of Seismic, along
with the results of research drilling (White and
others, 1975), provide the keys for understanding
the origin of craters and vents of other geysers and
probably also of the large smooth-walled pools. New
fractures result from vigorous seismic disturbance
of large high-temperature convection systems with
fluid pressure gradients 10 to 50 percent above hy-
drostatic. Near-surface enlargement of vents results
from flashing of water to steam in partly cemented
sinter and sediments; typical volume increases of
the fluid phases are 75 to 150 times the initial liquid
water volume (at 125° to 150°C) when erupted to
atmospheric pressure. Deeper enlargement of the
channel and local reservoir of each geyser probably
occurs because of extreme pressure gradients prob-
ably locally much above the lithostatic gradient.
Fountain-type geysers such as Seismic form where
near-surface rocks are incompetent enough to pro-
duce an upward-flaring vent as decompression oc-
curs and as wall materials are fragmented and
ejected. Cone-type geysers probably form where
near-surface rocks are relatively competent and re-
sist extensive fragmentation; most erupted water
drains away from the vent as Si02 is deposited lo-
cally to form cones or mounds.

Giant hydrothermal explosion crater in Yellowstone National Park

Evidence of a gigantic hydrothermal explosion on
the northeastern margin of Yellowstone Lake was
found by G. M. Richmond. The explosion deposit
forms a hemielliptic‘al ridge as much as 18 m high
that encloses an area about 4.8 km long northeast of
Mary Bay and about 2.4 km inland from the bay.
The deposit consists of large and small angular slabs
and chips of silica-cemented lake sand, silt, and till
in an unsorted matrix of sandy, silty clay. Some

 

165

rounded pebbles and cobbles, including a number of
glacial erratics, also occur in the material.

The explosion deposit overlies lake sand or varved
silt underlain by till of the last glaciation; all three
are locally silica cemented. The outer margin of the
deposit intrudes a thin organic lake-bottom sedi-
ment, carbon-14 dated by Meyer Rubin as 13,650:
650 yr old (W2894). The deposit is overlapped by
fine lake sand containing near its base a thin layer
of volcanic ash identified by R. E. Wilcox as the
12,000— or 12,600-yr-old Glacier Peak Ash, or pos-
sibly the St. Helens J. Ash. Charcoal 2 m above the
ash has been carbon-14 dated by Rubin as 10,900:
350 yr old (W2736). Muflier and others (1971) have
suggested that a sudden lowering of hydrostatic
pressure would touch ofl? a hydrothermal explosion
and that such a lowering could be brought about by
rapid draining of a lake. The sudden release of an
ice-dammed lake that existed in the northern ,part
of the Yellowstone Lake basin at that time prob-
ably caused the explosion.

Yellowstone’s deep plumbing

New studies of Yellowstone hot-spring waters by
A. H. Truesdell, R. O. Fournier, W. F. McKenzie,
and Manual Nathenson were made by using geother-
mometer methods capable of indicating the tempera—
tures of progressively deeper parts of geothermal
systems (silica and cation geothermometers, mixing
model calculations, and the sulfate-water isotope
geothermometer). These investigations, combined
with the recent geophysical evidence that the Yel-
lowstone caldera may be underlain with magma at
shallow (10 km?) depths, suggest that the caldera
contains an extensive aquifer with hot (370i°C),
moderately saline (1,000 ppm NaCl) water that
escapes upward where suitable fractures exist. Many
relatively small and cooler reservoirs exist in the
shallow parts of the hydrothermal system. Although
the residence time of water within these reservoirs
is variable, the overall rate of upward flow between
reservoirs and to the surface is rapid. The chemistry
of the ascending waters is altered by dilution, reac-
tion with rocks, and steam separation. The highest
temperature likely to be attained by dilute convect-
ing vapor-saturated water is about 370: °C because
heating to slightly higher temperatures induces very
substantial increases in volume (30 percent increase
between 370° and 374°C). Thus, convecting fluid
near the critical point may serve to regulate tem-
peratures in deep geothermal systems.

166

Geothermal reservoir temperatures estimated from the oxygen-
isotope composition of dissolved sulfate and water from hot
springs
The 013/016 and D/H ratios of waters and 015/

016 ratios of dissolved sulfates from hot springs
were determined in six major geothermal systems
in Yellowstone National Park, Wyo., by W. F. Mc-
Kenzie and A. H. Truesdell. Values of 8018/ (H20)
varied with chloride content, but 8018 (804—2) was
nearly constant (—12i1 per mil relative to
SMOW) for most waters studied. Steam-loss and
mixing models were used to estimate the 018/016
ratio of the deep reservoir water for each system.
The residence time of dissolved sulfate in the deep
reservoir is sufficient to ensure isotopic equilibrium
between dissolved sulfate and water, and waters as-
cend to the surface rapidly in relation to the rate
of isotopic exchange. Except for waters containing
sulfate of surficial origin, calculated temperatures
of last sulfate-water isotopic equilibrium ranged
from 320° to 420°C for all geothermal areas within
the Yellowstone caldera. These temperatures are
higher than those indicated by other geothermo-
metric methods.

Calculation of deep reservoir temperatures from chemistry of
boiling hot springs of mixed origin

Geothermometers based on the contents in hot
springs of SiOZ, Na, K, and Ca are successful in in-
dicating subsurface temperatures below 200° to
300°C. For higher temperatures, reequilibration us-
ually occurs during passage of the water to the sur-
face. If hot and cold waters mix in the subsurface,
indications of maximum temperatures may be pre-
served. Computations based on the chemistry of
mixed springs of less than 80°C have been previous-
ly described by Fournier and Truesdell (1974).

A new method was devised by A. H. Trusdell and
R. O. Fournier to calculate deep temperatures and
hot-water fractions for mixed springs that issue at
boiling temperatures. In the following equations,
Cl is the chloride content; Hw, H8, and Hm, are spe-
cific enthalpies at the surface temperatures of water,
steam, and evaporation, respectively; H.“ is the
enthalpy of liquid water at the temperature indi-
cated by the silica geothermometer; and the super-
scripts m, n, and 6 indicate mixed, nonmixed, and
cold springs, respectively. The parameters H" and
X are the specific enthalpy and mass fraction of the
hot. component of the mixed water:

Cl"'Hwa"(Ha’"—Hallm) +Cl’"Hm'”(Hsn"'—Hu-‘) —- ClCHwa’U‘st'"
X:

 

Cl"stm(Hs"—-Hw°) —Cl°le"Hw-"'

 

GEOLOGICAL SURVEY RESEARCH 1975

Hsilm_ch

X

Temperatures are determined from specific en-
thalpy by reference to standard steam tables. The
method has successfully predicted observed deep
temperatures for drilled geothermal systems in New
Zealand and Chile.

Geothermal modeling

H”: +va

To gain experience in solving multiphase flow
equations, several one-and two-dimensional finite
element and finite difference models were developed
by J. W. Mercer, C. R. Faust, and G. F. Finder and
applied to the classical Buckley-Leverett problem of
water flooding a petroleum reservoir. Using their
experience from isothermal‘ multiphase modeling,
they developed and solved partial differential equa-
tions describing heat transport in a steam-water-
rock system by means of a Galerkim finite element
method. The final equations are in terms of the
dependent variables pressure and enthalpy and are
valid for flow of compressed water, steam-water
mixtures, and superheated steam; thus, the numeri-
cal model is capable of simulating both hot-water
and vapor-dominated geothermal reservoirs. The
model also allows for phase changes and therefore
can simulate the transition of a hot-water reservoir
to a steam-water reservoir (for example, the Wair-
akei, New Zealand, geothermal field). Numerical
tests have been successfully conducted; however, no
field application has been attempted thus far.

Traces of deep saline brines in most subsurface dilute waters

D. E. White concluded that probably huge quan-
tities of saline fluid-s of various origins have circu-
lated through the “fossil” geothermal system of old
hydrothermal ore deposits. The ore fluids, common-
ly ranging from 1 to 40 percent in dissolved salts,
were generally being diluted by meteoric water dur-
ing ore depositions and were eventually completely
flushed by such water.

Deep saline waters of all kinds are eventually dis-
placed as a general consequence of compaction, pro-
gressive metamorphism, and convective flushing re-
lated to igneous activity and may generally leave no
obvious permanent record of their earlier passage
such as recognizable ore deposits. Total volumes of
such saline fluids are unknown but must be many
thousands of cubic kilometres. An important con-
sequence of this conclusion is that any water of low
to moderate salinity is likely to have a small propor-
tion of “deep” saline water, commonly of non-
meteoric origin. Chemical and isotopic criteria are

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

not yet precise enough to identify very small propor-
tions of such waters, but characteristic “signatures”
_ may eventually prove useful.

In recent years, many geochemists have explained
the chemical compositions of subsurface waters as
products of the interaction of meteoric waters with
their associated rocks, without involving any saline
component of “deep” or mixed origin. However, the
common occurrence of ore fluids of high salinity and
diverse origins and the evidence for dilution and
eventual flushing of such fluids by meteoric water
imply that most subsurface waters of moderate sa-
linity are likely to be mixtures of saline and dilute
waters.

Structural control of steam resources in The Geysers steam field,
California

Comparison of recent geologic, geoelectric, and
microearthquake data in the Geysers-Clear Lake
area by R. J. McLaughlin and W. D. Stanley indi-
cated that economically significant steam resources
can be related to local fault-controlled structural
traps in two areas. In one area of steam production
near the Geysers ,Resort, extensive hydrothermal
alteration and numerous microearthquakes are as-
sociated with N. 30°—40° W.-trending faults that
dip steeply to the northeast. Evidence of recent fault
activity, including tilted 750:105-yr-old steam de-
posits,- reinforces a correlation of the fault zone with
the microearthquakes. The association of the micro-
earthquakes and the hydrothermal alteration is in-
terpreted to indicate that rocks in the fault. zone are
saturated by a high column of hot water that over-
lies the steam reservoir.

A few kilometres southeast of the Geysers Resort,
near Castle Rock Spring, steam production is from
an area of anomalously low resistivity, also presum-
ably due to rocks saturated by a structurally high
column of hot water above the steam reservoir. The
area underlain by these rocks of low resistivity is
overlain by southeastward-dipping graywacke, ba-
salt, and serpentinite and is bounded on the north
and south by steep-dipping N. °80 W.-trending faults
and on the east by steep-dipping N. 50° W.-trend-
ing faults.

SEDIMENTOLOGY

Sedimentology, the study of sediment and sedimen-
tary rock, encompasses investigations of principles
and processes of sedimentation and includes develop-
ment of new techniques and methods of study. Sedi-

 

167

mentology studies in the USGS are directed toward
(1) solution of water—resource problems and (2) de-
termination of the genesis of sediment and applica-
tion of this knowledge to sedimentaryrocks for more
precise interpretation of their depositional environ-
ment. Many USGS studies involving sedimentology
apply to other topics such as marine, economic, and
engineering geology and to regional stratigraphic
and structural studies; these are presented elsewhere
in this volume under their appropriate headings.

Studies of fluvial sedimentation are directed to-
ward the solution of water-resource problems in-
volving water-sediment mixtures. Sediment is being
considered more and more as a pollutant. Inorganic
and organic sediment, transported by streams to
sites where deposition takes place, carries major
quantities of sorbed toxic metals, pesticides, herbi-
cides, and other organic constituents that accelerate
the eutrophication of lakes and reservoirs. Knowl-
edge of erosion processes, the movement of sediment
in rivers and streams, and the deposition of sediment
in stream channels and reservoirs isiof great eco-
nomic importance to the Nation.

VARIABILITY 0F SEDIMENT YIELDS

Sediment yields of Ohio streams

P. W. Anttila and R. L. Tobin defined fluvial sedi-
ment yields and characteristics in Ohio, incorporating
5 yr of periodic data from 39 sites on natural-flow
streams with current and historic daily sediment
data from 12 streamflow stations. Extension of the
daily sediment data to a 25—yr base period, 1946-70,
showed that annual suspended-sediment yields in
Ohio range from 54 to 185 t/kmz. The extended
yields were determined by°a least squares regression
of the logs of annual suspended-sediment discharge
with the log of the product of annual mean water
discharge and the sum of annual peak-water dis-
charge above a given base discharge. Standard errors
of estimate for the regressions ranged from 12 to 36
percent.

Bedload, estimated by using Maddock’s classificar
tion, was found to be less than 10 percent of the total
annual suspended-sediment discharge for most
streams.

Data from suspended-sediment particle-size analy-
ses suggested a good correlation with soil types and
State physiography. Clay content in excess of 80
percent was common in the northwestern quarter of
the State, but decreased to slightly less than 50 per-
cent in the eastern part of Ohio. Sand content gen-

168

erally represented less than 10 percent of the sus—
pended sediment, averaging less than 5 percent in
the northwestern part of the State and less than
15 percent in the Appalachian Plateau in the south-
eastern part of the State.

Estimates of sediment yield in the Arkansas River basin, Kansas

W. R. Osterkamp’s studies of sediment yields in
the Arkansas River basin of Kansas led to-develop-
ment of a method of estimating sediment yields from
unsampled basins. Average slope is determined from
topographic maps, and average runoff is measured;
runoff is interpolated from data for nearby basins if
discharge data are otherwise unavailable. A normal
sediment yield is determined from an empirically
derived curve that relates average annual sediment
yield to mean runoff. The estimated yield for the
basin is adjusted by applying an exponential power
of the slope.

Preliminary comparisons of estimated sediment
yields with actual yields determined from suspended-
sediment samples indicate that runoff and slope are
primary determinants of sediment yield. Geologic
variations generally seem to cause only minor differ-
ences, whereas land-use practices, hydraulic struc-
tures, and other man-induced changes have signifi-
cant effects.

Sediment discharge in the Umpqua River basin

Annual sediment yields in the central and upper
parts of the Umpqua River basin, Oreg., range from
less than 105 to 700 t/kmz. Results of studies by
D. A. Curtiss (1975) showed that the lowest yields
are from the Upper Cow Creek, Olalla Creek, and
South Umpqua River in the southern part of the
basin. Yields are greatest from Lookingglass Creek
and the South Umpqua River below the mouth of
Cow Creek in the central part of the basin. That area
is characterized by cultivated broad alluvial valleys,
whereas the upstream areas are essentially forested.
Sediment yield from the North Umpqua River basin
is moderate, 214 t/km2 from a 3,480-km2 area, much
of which is forest.

Sediment yields of Minnesota streams

Estimates of the annual suspended-sediment yield
and of the expected range of suspended-sediment
concentrations were made for rivers in Minnesota.
These estimates by C. R. Collier (1974) were based
on 4 yr of record of 21 daily or periodic stations on
18 rivers throughout the State.

Estimated annual sediment yields range from 0.7
to 7 t/km2 in the forested northeastern and north-

 

GEOLOGICAL SURVEY RESEARCH 1975

central lake regions of the State, 14 to 42 t/km2 in
the lower Minnesota River basin in the south-central
part, to more than 175 t/km2 in the extreme south-
eastern part. Peak suspended-sediment concentra-
tions during storm runoff seldom exceed 500 mg/l in
most northern streams but may approach 10,000
mg/l in southeastern streams. During periods of uni-
form flows, suspended-sediment concentrations are
generally less than 50 mg/l in the northern streams
compared to nearly 200 mg/l in the southeastern
streams.

Sediment yields high in Oregon coast streams

Sediment yields from 13 streams along the central
Oregon coast range from moderate to high, accord-
ing to Antonius Laenen and F. J. Frank. The 13
streams drain basins on the western slope of the
Coast Range and vary in size from 4.7 to 865 kmz.
The smallest sediment yield, about 80 t/kmz, was
from Beaver Creek, which drains an area of 37 kmz.
The highest yield, nearly 490 t/kmz, was from Drift
Creek, which drains a 97 .4-km2 area. Most streams
had yields of about 140 t/kmz.

These sediment- determinations were based on
synthesized daily sediment records developed by cor-
relating data from miscellaneous sampling with daily
data from nearby sediment stations in the Alsea
River basin. The determinations should be reliable
because of the excellent correlations obtained.

Sediment yield in the Lake Tahoe basin, California

The relative magnitude of sediment contributed to
Lake Tahoe from State highway cuts was demon-
strated in a study by C. G. Kroll (1974). During
water years 1972—74, less than 100 t/ yr of sediment
finer than 62 um was contributed by State highway
cuts. An unknown portion of the estimated 100 t/ yr
was contributed to the highway surface as mud fall-
ing from passing vehicles. The estimated long-term
annual sediment discharge into the lake from 6
streams is 6,440 t, of which 2,090 t is finer than 62
am. During the period 1972—74, 65 percent of the
water and sediment discharge occurred during snow-
melt runoff. In most streams, almost all sediment is
transported in suspension.

Sediment transport from highway construction sites

Suspended sediment transported by several small
streams was measured to determine the effectiveness
of sediment-control measures in reducing sediment
transport from highway-construction sites. J. F.
Truhlar, J r., and L. A. Reed (W. G. Weber and L. A.
Reed, 1975) found that the sediment transported

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

from a construction site was predominantly clay;
clay made'up about 65 percent of the sediment trans-
ported even though the construction soils were only
20-percent clay. The large amounts of clay restrict
the effectiveness of sediment-control techniques,
such as rock dams and sediment traps. The study is
being done in cooperation with the Pennsylvania
State Conservation Commission and the State De-
partment of Transportation.

Sediment-transport characteristics of North Carolina streams

The sediment-transport characteristics of streams
were determined in a 15,540-km2 area of the Coastal
Plain and Piedmont regions of eastern North Caro-
lina during the period 1969—73. The study by C. E.
Simmons (1975) covered all or parts of 21 counties
and included data for 28 sediment-sampling stations.
Annual suspended-sediment yields ranged from 4.4
to 115 t/kmg. There is a decrease in suspended-sedi-
ment yield in an eastward direction from the Pied-
mont to the Coastal Plain.

Sediment characteristics are directly affected by
topography, storm runoff, geology, land use, and
manmade detention structures. At one sampling sta—
tion during the 1973 water year, 44 percent of the
annual suspended-sediment load was transported
during 34 d of high flow. In the Piedmont region,
sediment yields vary indirectly with the percentage
of forest cover in the basin, but no definite relation-
ship is apparent between forest cover and yield in the
Coastal Plain. Most suSpended sediment transported
during floods in Piedmont streams ranges in size
from sands to silts, whereas the suspended material
in flooding streams in the Coastal Plain generally is
clay size.

Sediment yields in Colorado oil-shale region

Sediment yields were estimated by D. G. Frickel,
L. M. Shown, and P. C. Patton (1975) for 32 typical
subbasins in the oil-shale region of Colorado, using
a qualitative rating system involving climatic, geo-
logic, basin, and channel characteristics. The esti-
mates ranged from 48 to 333 kam2 for basins with
areas from 0.8 to 1,629 km2 under present, unmined
conditions. Erosion transects on 26 hillslopes and 11
channels showed little change during 1 yr of
observation.

Erosion from coal-mining spoils in Wyoming

During the summer of 1974, G. C. Lusby applied
simulated rainstorms of 38 mm in 45 min to small
basins in two coal surface-mining areas in Wyoming.
Runoff and sediment yield resulting from these

 

169

storms were measured on reclaimed spoil piles and
from nearby undisturbed areas. The test areas aver-
aged about 232 m2 and were on slopes of about 18
percent. Two tests were made at each site; the first
was made during prevailing antecedent moisture con-
ditions and the second was made after the site had
dried somewhat from the first test.

A good stand of introduced grasses was present on
the spoils at area 1. Density of vegetation was about
17 percent greater than on the nearby undisturbed
area. Despite the greater amount of vegetation pres-
ent, runoff was about 12 percent greater and sedi-
ment yield was about 3 times greater from the re-
claimed area than from the undisturbed area. At area
2, runoff was about 9 times greater and sediment
yield was 90 times greater from the reclaimed area
than from the undisturbed area. These large differ-
ences apparently resulted from the replacement of
surface soils with soils containing more clay. Soils
on the reclaimed areas contained' about 20 percent
more clay than the natural soil.

Determining sediment discharges from continuous turbidity

records

J. F. Truhlar and W. P. Schaffstall reported that
turbidity data were useful in computing suspended-
sediment discharge in streams affected by highway
construction. Data collected at several sites down—
stream from areas of active construction in Penn-
sylvania showed good correlation for individual
streams between discharge-weighted daily mean tur-
bidity and discharge-weighted daily mean suspended-
sediment concentration. When suspended—sediment
data were insufficient for computing suspended-sedi-
ment discharge, the discharge-weighted daily mean
turbidity was computed from continuous turbidity
records and water-discharge data. The discharge-
weighted daily mean suspended—sediment concentra-
tion was then determined from the correlation curve
and used to compute the suspended-sediment dis-
charge. This method is a significant improvement
over estimating the suspended-sediment, discharge
from a sediment-transport curve for streams affected
by construction, and it may also yield better results
for streams not affected by construction.

Effects of off-road vehicles on sediment yield

Information obtained during the 4-yr study of an
area in western Fresno County, Calif., by C. T. Sny-
der showed that areas used for hill climbing by off-
road vehicles produced larger amounts of runoff and
sediment and seemed to develop pipes or solution
channels more readily than an area not so used

170

(R. F. Miller and C. T. Snyder, 1973). The under-
ground channels enlarge during storms, thus con-
tributing to increased sediment yield. It had been
speculated that rodent holes might be the focal point
for the piping, but this argument was not. supported
by any increase in the number of pipes in the unused
area. The vegetative cover, originally damaged by
motorcycles and later damaged by a series of un-
usually dry years, 'was not improved greatly by pre—
cipitation during the 1974—75 winter.

SEDIMENT TRANSPORT AND DEPOSITION

Unstable sediments on the Mississippi Delta

In cooperation with investigators from the Coastal
Studies Institute of Louisiana State University, a
series of four borings were made into the submerged
portion of the Mississippi Delta by L. E. Garrison
and J. S. Booth in order to gain a better understand-
ing of the mechanisms responsible for sediment in-
stabilities. The sites, which lay in depths of water
ranging from 25 to 100 m, were drilled to depths of
30 to 60 m below the mudline. The locations chosen
represented a variety of bottom conditions, ranging
from areas with a known history of failure to areas
where the shallow acoustic stratigraphy indicated
stability throughout Holocene time.

Geochemical analyses of the pore waters in recov-
ered samples showed the presence of methane in
amounts as high as 1.7 ml/l. These methane amounts
bore an inverse relationship to dissolved sulfate,
lending support to geochemical model results of
methane generation by sulfate-reducing bacteria.
Furthermore, a fairly good correlation of high
methane with low shear strength indicates that
methane was present in a gaseous state and played
an important role in the loss of sediment strength.

The area selected for its stable history contained a.

25-m-thick zone high in methane content and low in
shear strength, suggesting that gas generation in
delta sediments spreads radially from centers of de-
position and mobilizes deposits which have previous-
ly been stable. Rates at which this process proceeds
, have not yet been established.

CHANNEL SCOUR

Fluvial morphology at bridge crossings

W. J. Randolph and T. L. Kelly reported that an
investigation of 19 western Tennessee bridge scour
sites, including four sites Where bridge failure oc-
curred, indicates that scour problems at bridge cross-
ings are often caused by manmade changes in the

 

GEOLOGICAL SURVEY RESEARCH 1975

channel or flood plain after construction of the
bridge. Channel enlarging and straightening resulted
in lowering and widening the channel, channel degra-
dation (or sometimes aggradation) owing to change
in hydraulic slope, and increased scour at bridges
owing to increased velocities.

Flood-plain modifications at some sites resulted in
less efficient flow conveyance and higher stages. EX-
amples of flood-plain modifications ranged from
channel encroachments and fill material pushed un-
der overflow spans to the complete blockage of two
overflow bridges by a downstream levee.

AERIAL PHOTOGRAPHY

Sources of erosion in the Broad River basin, South Carolina

In order to locate sources of erosion in an area
within the Broad River basin and to determine the
feasibility of correlating film density with suspended-
sediment concentration, S. J. Playton studied aerial
photographs and suspended-sediment samples for
two flow regimes. Playton determined that no signifi-
cant quantities of sediment are gained or lost to the
system except in Parr Shoals Reservoir. In Parr
Shoals Reservoir, it appeared that during low- to
average-flow conditions, suspended sediment was
deposited, and during higher streamflows the de-
posited material was resuspended and transported
downstream. Little success was realized in the at-
tempt to correlate film density with suspended-sedi—
ment concentration during low streamflow, and the
quality of aerial photographs collected during higher
streamflow was not good enough to allow correlation.

GLACIOLOGY

Research in glaciology—the study of seasonal
snowcover, ice, glaciers, and ground ice—by USGS
scientists is directed mainly toward a better under-
standing of snow and ice as a water resource. Snow-
melt produces much of the Nation’s streamflow; gla-
cier ice contains vast amounts of water in storage,
self-regulates the release of this water, and may
provide sensitive indications of climate change;
river and ground ice may make difficult the develop-
ment of water resources and transportation corri-
dors in Alaska and other northern states.

Tidal glacier studies

Columbia Glacier, the largest tidal glacier in
Prince William Sound, Alaska, has maintained a calv-
ing front at about the same location for the last

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

several centuries, whereas other tidal glaciers have
catas-trophically retreated. Austin Post postulated
that Columbia Glacier presently ends on a shoal en—
closing a deep, glacier-filled fiord and that a small
retreat of the terminus could result in a catastrophic
breakup of as much as 30 km of the glacier in a
period of about 50 yr. Post, M. F. Meier, and L. R.
Mayo, using the University of Alaska’s research
vessel, Acona, and its radio-controlled boat, Firefish,
made a hydrographic survey of the water depth at
the front of Columbia Glacier. Shoals from 2 to
about 30 m deep were found along the glacier’s ter-
minus, confirming Post’s hypothesis.

Glacier hydrology

A pilot study by S. M. Hodge (1975) during 1973
and 1974 on South Cascade Glacier, Wash., demon-
strated that borehole-drilling techniques can be used
to assess a subglacial water system. The water level
in the boreholes probably represents a direct meas-
urement of the basal water pressure. Indications are
that a single borehole is representative over a do—
main at least 10 m in extent. Pronounced fluctuations
in borehole water levels (up to 40 m) occur typically
over periods of several days and seem to follow by
about 2 d period-s of increased water input at the
glacier surface. The long—term trend in water levels
supports the idea of seasonal storage and release of
liquid water in glaciers.

Numerical methods in glaciology

L. A. Rasmussen (1974a) described a digital-
oomputer program that provides bihourly direct-
beam solar-radiation values and daily totals for one
or more sites anywhere on the Earth, for one or more
days of the year, for eight different atmospheric
transmissivity values. A site may have arbitrary ele—‘
vation above sea level and arbitrary topographic
horizon, and the plane of the site may have arbitrary
inclination from the horizontal (including vertical).
The program gives the true solar times of sunrise
and sunset as well as of the beginning and conclusion
of other topographical obstructions of the Sun.
Mathematical relationships are used to determine the
instantaneous position of the Sun, its angle of inci-
dence on the plane of the site, and the depletion of
radiation due to atmospheric absorption and scatter-
ing. Simple algebraic expressions are used that close-
ly approximate published empirical data for atmos-
pheric refraction and for the length of the atmos-
pheric path traversed by the Sun’s rays. The annual
variation of solar declination and intensity is ac-
cepted by the program as input data. This provides

 

171

the user the option of supplying the data for any
particular year. Care has been taken in the FOR-
TRAN coding to enhance the ease of installation of
the program on the widest possible selection of

computers, both existing and anticipated, of the

preparation of input data and the use of the output
data, and of possible modification of the program to
serve specialized purposes. The results are useful in
modeling snowmelt and in many other applications.

The computer programming of the generalized
three-dimensional, time-dependent flow model for
temperate glaciers described by L. A. Rasmussen
and W. J. Campbell (1973) was documented by Ras-
mussen (1974b). The term “generalized” is used be-
cause the dynamic behavior of a glacier is specified
by means of the following four flow parameters: (1)
the type of flow law to be used; (2) the exponent in
the power-law relationship in the selected flow law;
(3) the ice-to-ice viscosity coefficient for a Newtoni-
an viscous fluid; and (4) the ice-to-bed friction co-
efiicient. After the four parameters have been deter-
mined, the glacier is completely defined by specifying
only the topography of the surface underlying it and
the mass balance distribution. To aid in shortening
computation time, an initial thickness distribution is
estimated. Calculation of the flow of the glacier can
then be carried out for a period of arbitrary length.
The model was developed for the purpose of deducing
the optimum values of the four flow parameters by
applying it to existing glaciers. Care has again been
taken in the FORTRAN coding to enhance the ease
of installation of the program on the widest selection
of computers, both existing and anticipated, of the
preparation of the input data and the use of the
output data. and of possible modification of the
program.

PALEONTOLOGY

Research by USGS paleontologists involves bio-
stratigraphic, .paleoecologic, taxonomic, and phylo-
genetic studies in a wide variety of plant and animal
groups. The results of this research are applied to
specific geologic problems related to the USGS pro-
gram of geologic mapping and resource investigation
and to providing a biostratigraphic framework for
synthesis of the geologic history of North America
and the surrounding oceans. Some of the significant
results of paleontological research obtained during
the past year, many of them as yet unpublished, are
summarized in this section by major geologic age and
area. Many additional paleontologic studies are car-

172

ried out by USGS paleontologists in cooperation with
USGS colleagues. The results of these investigations
are ordinarily reported in “Regional Geological
Investigations.”

PALEOZOIC OF THE UNITED STATES

Redeposited trilobites in the Upper Cambrian of Nevada

The lower part of the Hales Limestone of the Hot
Creek Range in central Nevada contains Late Cam-
brian trilobites, according to M. E. Taylor. Two types
of trilobite assemblages are recognized on the basis
of sedimentological characteristics: (1) Basinal as-
semblages that are characterized by numerous com-
plete exoskeletons, poor size sorting, and association
with thinly bedded dark-gray pyritic lime mudstones
and shaley partings between lime mudstone beds and
(2) allochthonous assemblages that consist of broken
and abraded fossil debris that occurs in lighter
colored lime grainstones and in the matrix of some
limestone breccias. The basinal assemblages are
thought to contain trilobites that lived in deeper
water basinal habitats, whereas allochthonous assem-
blages represent redeposited exuviae of trilobites
that lived in the upper slope or the shoal-water
habitats of a carbonate platform located in eastern
Nevada and western Utah.

Basinal assemblages contain trilobites that are
widespread in southeastern and northwestern China.
Allochthonous assemblages mostly contain elements
of the so—called “Hungaia magnified fauna,” which
was restricted to North American outer platform
and platform margin sites during the Late Cam-
brian.

The interbedding of trilobites with widely different
paleobiogeographic affinities provides a basis for
more refined correlations between the Upper Cam-
brian rocks of the Western United States and cen-
tral Asia.

Depositional environments of Ordovician fossiliferous

volcaniclastic rocks

Differences in water depth and distance from shore
around Early Ordovician volcanic islands are inferred
from contrasting fossiliferous volcaniclastic rocks
interbedded with lavas found at four places on New
World Island, Newfoundland, by R. B. N euman
(USGS) and G. S. Home (Wesleyan Univ.). At one
place, poorly sorted, obscurely bedded conglomeratic
sandstone consisting of red volcanic debris contain-
ing abundant gastropods and cephalopods as well as
abraded and broken brachiopods indicates nearshore
accumulation in shallow, turbulent water. Water-

 

GEOLOGICAL SURVEY RESEARCH 1975

laid tuifs at three places show different amOunts of
reworking that, together with differences in (1) the
abundance of calcareous algae, (2) the composition
of invertebrate fossil assemblages (largely brachio-
pods), and (3) the nature of fossil preservation (in—
cidence of shell articulation, evidence of shell bor-
ings), indicate deposition in progressively deeper
water. These interpretations should be useful in
identifying centers of volcanic activity in similar
rocks in Maine and elsewhere in the northern
Appalachians.

Early Devonian ostracodes from Nevada

A rich assemblage of silicified ostracodes has been
picked from residues from the Eurelcaspirifer ping/o-
nensis zone of the McCoIley Canyon Formation
(Emsian) provided by J. G. Johnson (Oregon State
Univ.). J. M. Berdan (USGS) reported the presence
of more than 35 taxa, of which 3 genera and many of
the species are new. The assemblage is a mixture of
Appalachian forms and forms with Eurasian affini-
ties and includes one species that hitherto has been
found only in the Early Devonian part of the Mc-
Cann Hill Chert in Alaska.

Septal carinae in Devonian corals

Study of the microstructure of carinae in Middle
Devonian Heliophyllum (rugose coral) from New
York by W. A. Oliver, Jr., and J. E. Sorauf
(S.U.N.Y., Binghamton) showed that three distinct
types exist. Type I (simple, monacanthine trabe—
culae) is the only type found in earlier H eliophyllum
and in the early ontogenetic stages of all H eliophyl—
lum. Types II (compound trabeculae, branching pro-
lifically) and III (compound, branches few and
parallel) appear higher in the section but only in the
mature stages of individuals.

In the higher part of the section (Tioughnioga
Stage), all samples studied have one dominant
carina type that appears in over 75 percent of the
individuals studied from that sample, but different
types predominate in different stratigraphic (that
is, lithologic) units. Thus a selection pressure favor-
ing the type best adapted to the local environment
is suggested. Colonial H eliophyllum have been stud-
ied only in collections from the Deep Run Member
of Cooper (1930) of the Ludlowville Formation;
predominant types are as follows: branching colon-
ies, type I; massive colonies, type III; and solitary
Heliophyllum from the same unit, type II. Further
study of colonies may help determine whether this
apparent linkage of growth form and carina type is
constant or also varies with stratigraphic unit.

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

Late Ordovician Bryozoa in Western United States

Collections of Ordovician bryozoans from Nevada
and Wyoming submitted to O. L. Karklins for iden-
tification by T. B. Nolan and R. J. Ross, J r., extended
the geographic range of the trepostomes Callopo-
rella, Batostoma manitobense Ulrich, Rhombotrypa
cf. R. multitabulata Utgaard and Perry, and cryp-
tostomes Goniotrypa, Pachydictya hexagonalis U1-
rich, and Sceptropo'ra. Calloporella, Batostoma cf.
B. mam'tobense, Goniotrypa, and Sceptropom are
found in a yet unnamed lithic unit, probably of Late
Ordovician age, in Beacon Peak quadrangle in Ne-
vada. Of these bryozoans, Gom‘otrypa and Sceptro-
para occur in the Stony Mountain Formation in
Manitoba, Canada, and in the Eastern United States,
but Calloporella occurs only in the eastern regions.
In Kentucky, Calloporella appears to be restricted
to the Garrard Siltstone (Weir and Greene, 1965)
in south-central Kentucky. Batostoma manitobense,
however, occurs in the upper member of the Bighorn
Dolomite in the Hidden Tepee Creek quadrangle and
in the Stony Mountain Formation but has not been
reported from the eastern regions.

Rhombotrypa cf. R. multitabulata and Pachy-
dictya hexagonalz's occur in the upper member of the
Bighorn Dolomite and in the Stony Mountain For-
mation. Of these bryozoans, only Rhombotrypa mul-
titabulata is found in the Whitewater Formation of
Indiana and Ohio (Utgaard and Perry, 1964).

North American Mississippian coral zoogeography

A study by W. J. Sando, E. W. Bamber, and A. K.
Armstrong of the distribution of coralliferous facies
and the degrees of endemism and generic similarity
of Mississippian coral faunas permitted recognition
of five zoogeographic provinces and five zoogeo-
graphic subprovinces in North America. Analysis of
indices of endemism and similarity suggests the fol-
lowing major conclusions: (1) Zoogeographic regions
on the periphery of the North American continent
had favorable connections for migration to other
coralliferous areas of the world, which permitted
maximum gene flow; (2) zoogeographic regions in
the interior of the North American continent were
relatively isolated genetically and were characterized
by coral faunas with low to high endemism through-
out Mississippian time; (3) gene flow was highest
along continuous shallow-water carbonate shelves
and was impeded by areas of terrigenous sedimenta—
tion and areas of deeper water; and (4) similarities
between faunas of different zoogeographic regions
generally tend to vary inversely with the migration

 

173

route distance between these regions, but other fac-
tors that affected gene flow modified the distribution
patterns significantly.

Biostratigraphy of the Mississippian Leadville Limestone,

San Juan Mountains. Colorado

In the San Juan Mountains, the Leadville Lime—
stone disconformably overlies the Ouray Limestone,
which is of Devonian (Famennian) age. Generally,
the Leadville Limestone can be divided into two
parts. The lower part, 2 to 50 m thick, consists of an
unfossiliferous dolomite and lime mudstone that
were deposited in subtidal to supratidal environ-
ments. Their age is uncertain. Overlying these are 2
to 26 m of pelletoid-echinodermmid-foraminiferal
packstones-wackestones that contain a mi-crofossil
assemblage of zone 9, which is of Keokuk age
(Osagean, late Tourn‘aisian). These fossiliferous
limestones were deposited in open, shallow marine
waters.

A regional unconformity and a pre-Pennsylvanian
erosion surface at the top of the Leadville Limestone
represent a stratigraphic hiatus encompassing Mera—
mecian, Chesterian, and probably parts of early Mor-
rowan time. The lowermost beds of the overlying
Pennsylvanian Molas Formation formed as a residu-
um composed of nonmarine mudstone, solution-
rounded limestones, and cherts on top of the Lead-
ville Limestone.

A major marine transgression occurred in zone 9
(late Osagean) time in northern Arizona, southern
Colorado, New Mexico, and southern Utah. The
crinoidal-foraminiferal limestones of the Leadville
Limestone of the San Juan Mountains are part of a
once—extensive carbonate sheet. Time-stratigraphic
equivalents, open marine carbonate rocks, are the
Mooney Falls Member of the Redwall Limestone of
the Grand Canyon in Arizona to the west and the
Kelly Limestone of west—central New Mexico to the
south. The Espiritu Santo Formation, to the south-
east in north-central New Mexico, is a subtidal-
supratidal facies of the zone 9 beds of the Leadville
Limestone.

Upper Devonian conodont biofacies in Western United States

Conodont faunas of the upper Famennian Poly-
gnathus stym’acus zone were recognized by C. A.
Sandberg in a large region of the Western United
States extending from northern Montana southward
to southern New Mexico and from central Nevada
eastward to central Wyoming. The faunas were de—
posited in environments ranging from bathyal to
nearshore marine. The eugeosynclinal and miogeo—

174

synclinal biofacies are well diversified and contain
many species that are readily correlatable with spe-
cies of the standard Upper Devonian conodontzona-
tion in Germany. The faunas of the cratonic plat-
form, however, contain few deep-water species and
become progressively more specialized shoreward.
Highly specialized nearshore cratonic biofacies con-
tain poorly known bizarre species that would be dif-
ficult to assign zonally were it not for their minor
mixing with better known deep-water species in
some outer cratonic platform biofacies. Recognition
of the great diversity of conodont bio-facies in a
single conodont zone permits paleoecologic interpre-
tations that will aid in analyzing depositional en-
vironments of petroleum source beds and also makes
possible age determinations of many previously un-
datable conodont collections from the cratonic in-
terior.

Invertebrate assemblages from the Kanawha Formation,

West Virginia

Sections described for the proposed Pennsylvanian
System stratotype in West Virginia have yielded
brachiopod faunas in several beds of Middle Penn-
sylvanian age. Preliminary evaluation of brachio-
pods collected and identified by T. W. Henry from
the Eagle limestone of White (1891) indicated a
correlation with the upper Morrowan Linoproductus
nodosus zone of the midcontinent region. This occur-
rence suggests that the top of the Morrowan Series
is actually within rather than at the base of the Mid-
dle Pennsylvanian Series, as early correlations had
indicated.

Evidence of Vojnovskyales in north-central Texas

The identification of the Vojnovskyales, typified
by Vojnovskya paradoxa N euburg 1955, is based on
gymnospermous fragments from the Lower Permian
of Siberia. These plants are characterized by fan-
shaped leaves and bisexual fructifications contain-
ing winged seeds and long, narrow polleniferous
organs; relationships of the plants within the gym-
nosperms are completely enigmatic.

A large suite of Permian plants from Texas and
Kansas, collected by S. H. Mamay, contained many
fan-shaped leaves, detached winged seeds, and one
partial cone with attached leaves and structures re-
sembling pollen organs; together, these organs close-
ly resemble those of Neuburg’s Vojnovskya. The
American fossils are much like the Vojnovskyales
and appear to represent a close link between the
American and Siberian floras, both morphologically
and chronologically.

 

GEOLOGICAL SURVEY RESEARCH 1975

Palynological analyses

Thirteen samples of the Laurel coal and associated
roof and seat rock collected from the Isonville quad-
rangle in eastern Kentucky were prepared and
examined for spore-pollen content by R. M. Kosanke.
The most abundant genus is Laevigatosporites; L.
globosus is the most abundant species, followed by
L. minutus and L. ovalz's. A single specimen of Zos-
terospom’tes triangularz’s was identified from the
seat-rock sample. This taxon previously had been
reported from the Princess No. 5 through the Prin-
cess No. 5B coal. Two samples of the Laurel coal
contained several specimens provisionally assigned
to Schopfites, which previously had been identified
from the Princess No. 6 and No. 7 coals of north-
eastern Kentucky. The e‘vidence suggests that the
Laurel coral does not correlate with either the Prin-
cess No. 5B or the Princess No. 6 coal but rather
occurs between these two coals. The occurrence of
a coal between the Vanport Limestone Member of
the Breathitt Formation and the Princess No. 6
coal is not unique. The Lawrence coal of Lawrence
County, Ohio, occurs at approximately this posi-
tion.

MESOZOIC OF THE UNITED STATES

Ammonoid fauna in Nacatoch Sand

A varied ammonoid fauna of very Late Cretaceous
age (Maestrichtian) was discovered in the Naca-
toch Sand in Hempstead County in southwestern
Arkansas by B. F. Clardy and W. V. Bush (Arkansas
Geological Commission). Collections made in 1973
and 1974 by Clardy with W. A. Cobban and R. E.
Burkholder (USGS) include Nostocems altematum
(Tuomey) and Solenoceras nitidum Cobban, species
previously known only from the Ripley Formation
of Mississippi, Alabama, and Georgia. Other ammo-
noids in the collections from the Nacatoch Sand con-
.sist of representatives of the genera Anagaudry-
cems?, Pseudophyllites, Baculz'tes, Discoscaphites,
and Sphenodiscus.

Fossil gymnosperm seeds from the Morrison Formation

Although remain-s attributed to the araucarian
conifers are common in Mesozoic rocks of the United
States, first proof that the modern Southern Hemi-
sphere genus Araucaria was present is furnished by
hundreds of silicified cone scales from a locality in
the Morrison Formation (Upper Jurassic) of Utah.
These fossils; studied by M. E. J. Chandler and R. A.
Scott, show that two sections of the extant genus
are represented, one still living in Australia and

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

the other extinct but related to the modern section
containing Amucaria bidwelli. About 10 other
genera of pteridosperms and cycadophytes are also
represented by reproductive structures at this 10-
cality. These plants are strikingly different from
previously described forms and reveal a floral di-
versity for Morrison time not suspected from the
scanty leaf fossils already known. No angiosperm
fossils are present.

CENOZOIC OF THE UNITED STATES

Latitudinal floral differentiation in the Paleocene

The presence of pollen grains of Thomsom'pollis
in the Paleocene part of the Dawson Formation of
Colorado is evidence for a latitudinal difference in
floras during the Paleocene, according to R. H.
Tschudy. Pollen of this genus is absent or extremely
rare in the Paleocene of Wyoming, Montana, and
North and South Dakota. This pollen, however, is
common in the Upper Cretaceous and Paleocene of
southern Colorado and New Mexico and in the up-
permost Cretaceous, Paleocene, and lower Eocene of
the Mississippi embayinent region. The northern
limit of the Thomsonipollis‘ floral province was prob-
ably about the latitude o-f Denver, Colo.

Pollen floras of the Pliocene-Pleistocene transition, west Snake
River Plain, ldaho

Rocks of the Idaho Group of the western Snake
River Plain contain a variety of plant fossils, in-
cluding fossil wood, fruits, leaves, and pollenl The
combined evidence gathered by earlier workers, in-
cluding evidence from a recent pollen study by E. B.
Leopold, revealed the following vegetation sequence
for the old flood plain of the Snake River, near
Glenns Ferry, Idaho: ‘

1. Hemphillian (Poison Creek Formation, Ban-
bury Basalt, and Chalk Hills Formation) :
mixed conifer and hardwood forest and wood-
land. Hardwood genera such as Cam/a, Ulmus,
Framinus, Alnus, Abies, and Salicaceae grew
at least near the river. Conifers were largely
Pinus.

2. Early Blancan (Glenns Ferry Formation) :
Pinus-Juniperus savanna a n d woodland.
Grasses predominated as understory. Climate
presumed to be moister than it is now.

3. Late Blancan and Irvingtonian (Bruneau For-
mation of middle Pleistocene age) : Artemisia
steppe, very open and treeless, as it is now.
Climate was probably as dry as it is now. Some

 

175

horizons (younger, undated) suggest an ad-
vance of Picea on the Snake River Plain.

The major phases of contrasting vegetation are of
interest in considering the environmental'setting in
which the rich local faunas of these periods oc-
curred. Since the modern vegetation of the area is
sage steppe, the late Tertiary fossils indicate a cli-
mate considerably more moist than that of today,
lasting at least until the beginning of the'Pleisto-
cene. In effect, the lower ledge of tree line has moved
upslope some 600 to 900 m since the Pleistocene.

Pliocene diatoms from the Teewinot Formation, Wyoming

A sequence of samples collected by J. D. Love and
G. W. Andrews from the Teewinot Formation at the
Boyle Ditch locality in the Jackson Hole National
Elk Refuge contained 75 taxa of nonmarine diatoms.
The frequent occurrence of at least seven extinct
nonmarine diatom taxa suggests an age not younger
than late Pliocene. The diatom assemblages contain
many benthic taxa, which suggest deposition in a
shallow lacustrine environment. Increases in the
abundance of the planktonic species M elosira italica
and M. granulata suggest occasional deepening of
the waters. The assemblages are predominantly
freshwater in character, but some contain compo-
nents of saline, salt-indifferent, and salt-tolerant
freshwater taxa. These suggest that seasonal fluc-
tuations in alkalinity and salinity occurred during
deposition. However, the common element running
through the sequence of assemblages indicates that
no profound environmental change occurred during
the deposition of these Teewinot sediments.

Delmontian diatoms and silicoflagellates

J. A. Barron investigated the diatom and silico-

~ flagellate biostratigraphy of the type Delmontian

Stage (upper Miocene) near Monterey, Calif. Early
late Miocene diatoms and silicoflagellates character-
istic of the lower Mohnian Stage at Newport Bay,
Calif., are present in the type Delmontian strata.
These results support the benthonic foraminiferal
studies of R. L. Pierce and suggest that the Del-
montian is coeval, at least in part, with the
Mohnian.

The type section of the Bolivina obliqua Zone
conformably overlies the Mohnian stratotype near
Los Angeles, Calif, and contains early Pliocene dia-
toms and silicoflagellates. This configuration sug-
gests that the Mohnian Stage extends into the Plio-
cene.

176

Miocene biostratigraphy, western Washington

New molluscan data from the Clallam Formation,
an 800-m-thick sandstone exposed along the north-
ern margin of the Olympic Peninsula, Wash., indi-
cated reassignment from the middle Miocene to the
lower Miocene, according to W. O. Addicott. Inner
sublittoral assemblages of the Clallam mark the con-
cluding phase of a late Eocene to early Miocene .de—
positional cycle in northwestern Washington. They
also represent a previously unrecognized time-strati-
graphic unit of at least zonal, if not stage, magni-
tude. This unnamed unit is co-eval with the upper
part of the “Vaqueros Stage” of California. It is
referable to the later part of the provincial lower
Miocene.

Miocene and Pliocene Cetacea from the Lee Creek phosphate
mine, North Carolina

The open-pit phosphate mine of Texasgulf, Inc.,
at Aurora in Beaufort County, NC, is the richest
known source of fossil marine mammals in the
world. The fossils come from the Pungo River For-
mation of middle Miocene age and the Yorktown
Formation of early and late Pliocene age. As they
are dug up by a 56-m3 dragline, the bones are
mostly fragmentary, but one partial baleen whale
skull, several porpoise skulls, and one pygmy
sperm whale skull were preserved in calcareous con-
cretions. Despite the fragmentary nature of the ma-
terial, F. C. Whitmore, Jr. (USGS), and J. A. Kal-
tenbach (George Washington Univ.) identified 11
genera of Cetacea from the Pungo River Formation
and 10 from the Yorktown Formation.

The Pungo River fauna shows closest affinity to
the fauna of the Calvert Formation of Maryland.
Particularly common, as in the Calvert, are remains
of the long-beaked porpoises Rhabdosteus and Far-
hinodelphia, the latter also being well known from
the Miocene of Belgium. At least three species of
Squalodontidae are present: Phocageneus cf. P.
yenustus Leidy, Squalodon cf. S. tiedemani Allen
(similar to, but not conspecific with, S. dalpiazi
Fabiani of the middle Miocene of Italy), and S.
calvertensis (probably conspecific with forms from
the Bolderian (middle Miocene) -of Belgium). Other
porpoise genera also found in the Calvert are Ken-
tm‘odon, Delphinodon, and Lophocetus. A few tiny
ear bones resemble those of the porpoise Normali-
thax from the Temblor Formation (lower and mid-
dle Miocene part) of California. Cetotheres (primi-
tive whalebone Whales) are present but cannot be
identified as to genus.

 

GEOLOGICAL SURVEY RESEARCH 1975

Whereas the Pungo River fauna consists of ex-
tinct genera, the Yorktown Formation, which in-
cludes representatives of living genera, has a de-
cidely modern aspect. More specimens are recovered
from the Yorktown, and it is possible to make a
rough estimate of the dominant members of its
fauna. On the basis of the number of earbones
found, the dominant Cetacea are dolphins (Del-
phinidae), pygmy sperm whales (Kogiinae), and
belugas (Delphinapterinae). The abundance of the
latter two is surprising: the pygmy sperm whale,
although known to have worldwide distribution, is
rare today, and the beluga, a small white Whale that
inhabits estuaries, is a cold-water animal and rare-
ly ventures south of the Gulf of Saint Lawrence.
Neither of these subfamilies is represented in the
extensive collections of Pliocene Cetacea from Bel-
gium in the Museum National d‘Histoire Naturelle
in Brussels. Many teeth of large sperm whales are
found in the Yorktown; some are indistinguishable
from teeth of the modern genus Physeter. The
modern beaked-whale genera Mesoplodon and Ziph-
ius are present, although rare. Among the baleen
whales, Balaenopteridae" (finbacks) and Balaenidae
(right whales) are common.

OTHER PALEONTOLOGIC STUDIES

New information on early Paleozoic bivalves

Significantnew information and discoveries about
the functional morphology, systematics, biological
placement, biostratigraphy, and phylogeny of early
Paleozoic bivalves were obtained by John Pojeta,
Jr. (USGS), in conjunction with Bruce Runnegar
(Univ. of New England, Armidale, Australia) and
J. H. Shergold and Joyce Gilbert-Tomlinson (Aus-
tralian Bureau of Mineral Resources). They dealt
with the long poorly understood fossils known as
the Ribeirioida, Conocardioida, and Fordilla, troy-
ensis.

Pojeta and Runnegar were able to show that F.
troyensis is the oldest known pelecypod mollusk
and that it is the only member of its class presently
known from the Cambrian. They also noted that,
in the earliest Cambrian, mollusks had already di—
versified into three classes: Monoplacophora, Gas-
tropoda, and Rostroconchia; subsequently, in the
late Early Cambrian, rostroconchs gave rise to the
Pelecypoda. Previously, it had been thought that
these classes of mollusks arose later in the Cam-
brian or in the Early Ordovician.

Poj eta and Runnegar have shown that the ribeiri-
oids and conocardioids form a new class of mollusks

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

called the Rostroconchia, which are neither bivalved
arthropods nor pelecypods. They have provided a
new biostratigraphic tool—a group of organisms
heretofore neglected because they were not recog-
nized as a biological entity—and have monographed
all known Cambrian and Ordovician species from
North America, western and central Europe, Si-
beria, north Africa, and Manchuria. Pojeta, Gilbert-
Tomlinson, and Shergold have monographed all
known Cambrian and Ordovician rostroconchs from
Australia and have established a rostroconch bio-
stratigraphy for the Upper Cambrian and Lower
Ordovician.

Canadian Arctic Albian (Cretaceous) foraminifers

Samples from the Christopher Formation on the
Amund Ringnes Island of the Canadian Arctic
Archipelago have yielded an Albian foraminiferal
assemblage consisting of 30 species. These faunas
represent an important biogeographic link between
Albian species recognized in Alaska and those recog-
nized in European localities, especially England
and northwestern Germany. The faunas are indica-
tive of a middle Albian age and are unusual by
Arctic standards in the number of calcareous spe-
cies represented. The species comprise a neritic as-
semblage from a section whose environment of depo-
sition‘ passed from a transgressive to a regressive
phase, according to W. V. Sliter. Recognition of the
successive bathymetric assemblages of these Albian
foraminifers provides important data for the paleoe-
cologic interpretation of Alaskan and Californian
species of similar age.

Metazoan imprints from 620-m.y.-old rocks in North Carolina

Large U- and J-shaped imprints of soft-bodied
Metazoa are abundant on a small bedding-surface
exposure about 16 km north of Durham, NC, in the
Carolina slate belt. They show a strong preferred
orientation, with the long axes trending N. 55° E. to
S. 55° W. It is believed that this orientation and per-
haps the U and J shapes were produced by currents
that carried the flaccid tubular structures down-
slope from the coast of an adjacent volcanic land
area. Available radiometric dating implies an age
near 620 my The most common type of U- and J-
shaped imprint is described as a new genus; it is a
sedentary, deposit- or filter-feeding polychaete an-
nelid. Other taxa may be present, including possibly
a turbellarian flatworm. These imprints constitute
the first record in the United States of the glob-a1
burst of soft-bodied metazoan diversification that
ushered in the Paleozoic Era and Phanerozoic eon.

 

177

Since its marine volcanogenic sediments are both
fossiliferous and capable of being radiometrically
dated at many points, the slate belt is a promising
region for delineating the base of the Paleozoic and
Phanerozoic and the relations betWeen Ediacarian
and Cambrian. P. E. Cloud, Jr. (USGS), is prepara
ing a report on these objects in collaboration with
James Wright (Univ. of California, Santa Barbara)
and Lynn Glover III (Virginia Polytechnical Insti—
tute).

GROUND-WATER HYDROLOGY

USGS ground-water hydrology research continues
to cover a broad range of subjects with the common
objectives of (1) better understanding ground-water
systems and (2) developing and applying new tech-
nical methods of study to improve management of
ground water as an important national resource.

Artificial-recharge studies.ranged from geological
and geochemical aspects of artificial recharge to
quantitative tests of percolation basins. ,

Research on the hydrology of carbonate-rock ter-
ranes included aquifer testing to determine the
water-bearing properties and the movement of con-
taminants through fractures.

Model simulation of aquifer systems, oriented to-
ward studying both flow and quality changes in
ground water, received much attention during the
year. Mathematical contributions included the de-
velopment of a finite-difference model for simulation
of ground-water flow in three dimensions.

Geophysical methods, including high-resolution
seismic reflection and direct-current resistivity, were
used successfully in investigating stratigraphic posi-
tions and lithologic characteristics of aquifers.

Results of other studies showed that ground-water
movement is influenced by the presence of subsidence
fissures in fractured rocks that overlie areas of
mined-out coal beds and that resultant changes in
ground-water circulation in these rocks may ac-
count for some capture of flow from wells and
springs, greater flooding of mines, and increased
acid mine-water discharge to streams.

Artificial recharge

Alaska.——Artificial-recharge operations were con-
ducted from May through November 1974 at a
40,500-m2 pit near Ship Creek in the Anchorage area.
G. S. Anderson and N. A. Matson, Jr., reported that
the infiltration rate of 0.3 to 0.45 m/d, total recharge
rate of 15,100 ma/d, and increase in potentiometric

178

head of 5.5 m in the vicinity of the pit are similar to
values obtained from a 2-mo test in 1973. Tempera-
ture logs from a Well at the edge of the pit indicate
that the 10° to 15°C Ship Creek water, which was
used for recharge operations, caused a local‘increase
in ground-water temperature. Normally; ground—
water temperature in the Anchorage area is between
3° and 4°C.

Florida—Predicted water shortages in southern
Florida have led to an investigation by F. W. Meyer
of the feasibility of injecting seasonal surpluses of
freshwater runoff into saline artesian aquifers as a
water-conservation measure. A 335-m test well is
under construction at a site near the city of Miami’s
water-treatment plant at Hialeah to identify poten-
tial injection zones. Plans call for initial injection of
ground water to determine the feasibility of recover-
ing the injected water.

Kansas—Ponds used for artificial-recharge tests
in western Kansas gradually became plugged by
sediment deposition and biological activity that re-
duced recharge rates. J. B. Gillespie showed that till-
ing of the native sod (derived from loess) in the
ponds restores the recharge capacity of the ponds.
In 1973, 40.5 m of water was recharged through a
pond in 27 d; in 1974, after the deposited sediments
were tilled, the test pond recharged 40 m of water in
a similar period.

Texas—Results of laboratory studies by D. C.
Signor, W. W. Wood, and R. F. Brown showed that
the condition of a sand-grain surface has a major
effect on retention of infiowing clay and clogging of
a porous matrix. Washed and acidized sand from the
Ogallala Formation retained a coating of clay and
iron oxide on the grains. Repacked columns of sand
of two size ranges (74—595 pm and 120—1,680 pm)
and with the same relative particle-size distribution
were subjected to a clay-suspension inflow. The clay
suspension was 500 mg/l of a sodium montmorillonite
with an initial inflow velocity of 0.2 cm/s. After 230
min of flow, the average intrinsic hydraulic conduc-
tivity was reduced by 93 percent for the 74- to 595-
,im sand size and 78 percent for the 120- to 1,680-Mm
sand size.

In a similar experiment, a major part of the clay
coating was removed from the sand grains by me-
chanical stirring, but the particle—size range and dis-
tribution were changed only slightly. After 284 min
of clay-suspension inflow, the intrinsic hydraulic con-‘
ductivity of the fine material was reduced 60 percent,
and that of the coarse material was reduced 57
percent.

 

GEOLOGICAL SURVEY RESEARCH 1975

Evaluation of factors affecting clogging should aid
in site evaluation when feasibility of artificial re-
charge is to be determined.

Wisconsin—Results of a study by R. P. Novitzki
showed that recycling water to the ground-water
system is an effective means of increasing the quan-
tity of water available for use, of controlling or
avoiding environmental pollution, and of controlling
water temperatures. Waste water from a fish hatch-
ery was recharged to the ground-water system
through an infiltration pond for 15 mo. Subsequent
calculations showed that 83 percent of the recharge
water was recirculated to a nearby water-supply well.
Nitrate nitrogen levels in the water supply did not
exceed 4 mg/l throughout the recycling period. Mass-
balance equations relate nitrate nitrogen levels to
imposed loading and to the efficiency of the recycling
system.

Estimates indicate that the local aquifer could sup-
port operation of a hatchery producing more than
50,000 kg of cold-water fish without significant
degradation of the local water supply or the regional
ground-water system.

The temperature of the water supply also could be
predicted. Equations were developed that related
water-supply temperature to air temperature, the
size of the recycling system, and the recycling effi-
ciency. During operation of a full-scale hatchery,
utilizing continuous recycling, water-supply tem-
peratures would range from 7° to 15°C. Water-sup-
ply temperatures could be maintained in an optimum
range (10°—16°C) if recycling were practiced for 8
mo of each year.

Hydrology of carbonate-rock terranes

In a continuing evaluation of the water-bearing po-
tential of carbonate rocks in east-central Iowa, K. D.
Wahl used air-inflated packers above and below a
submersible pump for testing selected zones to deter-
mine ground-water yield. The specific capacity of
zones tested in one well ranged from 1.76 to 0.0021
1‘s”1 m—l. Further refinement by borehole flow meter
indicated that the zone having a specific capacity of
1.7 6 was fed by one major opening at a depth of 65
m. Packer tests also allowed heads to be measured in
the different zones and resulted in a better under-
standing of ground-water movement in the area.

Carbonate rocks are a major source of ground
water for municipal, commercial, and domestic users
in eastern Wisconsin. Results of a study by M. G.
Sherrill indicate that-in areas of ground-water re-
charge, contaminants can enter the dolomite aquifer

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

through thin soil and glacial-drift cover and move
with ground-water flow through a well-developed
fracture system. Vertical fractures provide the ave-
nues by which both organic and inorganic contami-
nants enter the aquifer.

Mathematical methods in ground-water hydrology

A finite-difference model for simulation of ground-
water flow in two dimensions, originally developed by
G. F. Pinder (1970), was subsequently modified by
Pinder, (unpub. data, 1970), P. C. Trescott (1973),
and Trescott, Finder, and S. P. Larson (unpub. data,
1975). The most recent version is more completely
documented than previous versions and includes the
following options for solution of the simultaneous
finite-difference equations: (1) The IADI (iterative
alternating direction implicit) procedure, (2) line-
successive overrelaxation, and (3) the strongly im-
plicit procedure. Three options for numerical solu-
tion are included because the IADI procedure has not
converged for all problems.

A finite-difference model for simulation of ground-
water flow in three dimensions was written by Tres-
cott (unpub. data, 1975). The model uses the strong-
ly implicit procedure, a numerical procedure that
H. G. Weinstein, H. L. Stone, and T. V. Kwan (1969)
claim is less subject to roundoff error and converges
faster than IADI. The model has been used to obtain
a steady—state solution for ground-water flow in the
Piceance Creek basin in northwestern Colorado.
Twenty-one hundred nodes were used to simulate
two aquifers and an intervening confining bed; the
solution required 90 s of computer time on the IBM
370/155. J. B. Weeks (J. B. Weeks, G. H. Leavesley,
F. A. Welder, and G. J. Saulnier, Jr., 1974) obtained
a steady-state solution for this problem with a quasi-
three-dimensional model developed by J. D. Brede-
hoeft and G. F. Pinder (1970), but that model re—
quired more computer time, and numerical difficulties
were encountered. '

Aquifer model studies

As part of a continuing study of the alluvial aqui-
fer of the Ohio River valley in Kentucky, J. M. Ker-
nodle used a two-dimensional digital flow model to
simulate the aquifer’s observed response to a flood on
the river. Data for the model were obtained from
five sites at which two 3.81-cm-diameter observation
wells were augered and cased, and continuous water-
level recorders were installed. The results from four
of these sites were summarized by H. F. Grubb
(1975) .

.l

 

179

Simulated aquifer response was matched to the
observed response by adjusting the modeled hy-
draulic conductivity and specific yield of the aquifer,
as well as the hydraulic conductivity of the riverbed
and river bank. After obtaining a suitable match,
the digital model was used to illustrate theoretical
aquifer response to various simulated well-field de—
signs and pumpage rates.

Results of the study showed that the technique of
using the passage of a flood-generated wave through
the alluvial aquifer to calibrate a digital ground-
water flow model is both practical and, when com-
pared to conventional aquifer tests, relatively
inexpensive.

The USGS digital ground-water flow model (P. C.
Trescott, 1973) was used by L. F. Land to determine
the hydraulic characteristics of the shallow aquifer
at the sites of several pumping tests in Palm Beach
County, Fla. The aquifer responds as an artesian
aquifer with an overlying leaky confining bed.

The artesian sandstone aquifer of southeastern
Wisconsin and adjacent northeastern Illinois was
modeled by H. L. Young, using 1880—1973 pumpage
data. The digital-computer model covers 15,000 km2
in Wisconsin and 18,000 km2 in Illinois. Modeled
transmissivity ranged from 0.22><103 to 0.29X103
mg/d. Verification was obtained using vertical hy-
draulic conductivity ranging from 2.0X10—4 to
1><10—3 m/d in the recharge area, and from 1.2x
10‘6 to 0.8X10—4 m/d for the confining bed (Maquo-
keta Shale). Reasonable approximations of the actual
drawdown from 1880—1973 and from 1961—73 were
achieved. The Southeastern Wisconsin Regional Plan-
ning Commission will use the model in their planning
activities.

T. J. Durbin and J. A. Skrivan designed a computer
algorithm for the calibration of distributed-parame-
ter mathematical ground~water models. The algo-
rithm, based on the Gausse-Legendre least-squares
curve-fitting method (D. J. Wilde and C. S. Beightler,
1967), has been used to estimate transmissivity and
specific yield for a model of the Coachella Valley,
Calif.

Water-quality modeling

S. G. Robson used a profile-oriented water-quality
model to simulate hydrologic conditions in a well-
documented area in southern California where water-
quality degradation is associated with subsurface
waste disposal. The model was used to examine data
requirements, model parameter sensitivity, and ad-
vantages and disadvantages of the profile model

180

compared with those of an existing areal-oriented
water-quality model.

The profile model may be used to simulate confined
or unconfined aquifers with nonhomogeneous aniso-
tropic hydraulic conductivity and nonhomogeneous
storage coefficient, porosity, and saturated thickness.
The model input parameters were more difficult to
quantify for a profile model than the corresponding
parameters had been for the areal-oriented model.
However, the sensitivity of the profile model to the
input parameters is such that moderate errors of
parameter estimation allow acceptable model results.
Simulation of hypothetical groundwater-manage-
ment practices indicated that the profile model is
applicable to problem-oriented studies and can pro-
vide quantitative results for a variety of manage—
ment practices.

R. E. Fidler used a computer program to prepare
contour maps for selected ground-water-quality
parameters based on approximately 200 chemical
analyses of water from wells drilled in the limestone
and dolomite aquifers of western Ohio. This contour-
ing program is a flexible and relatively simple method
for comparing water-quality data to a regional
ground-water flow system. One map shows lines of
equal concentrations of dissolved solids which range
from 317 mg/l to 3,120 mg/l. The areal distribution
of dissolved-solids content as represented by the
contours suggests that areas of high mineral concen-
trations are areas of ground-water discharge and
areas of low mineral concentrations are areas of
recharge.

A comparison between surface- and ground-water
quality was made by superimposing the data from
chemical analyse-s of stream base flow onto the
ground-water—quality contour maps. The level of
concentration of selected parameters for base flow
is shown by a color pattern along the stream channel
and can be compared to the contours depicting
ground-water quality.

Geophysical methods

A high-resolution seismic—reflection investigation
of offshore areas adjacent to Lee and Collier Coun-
ties, Fla., was made by T. M. Missimer and T. H.
O’Donnell to determine the stratigraphic position and
geometry of the upper and lower Hawthorn aquifers
in the coastal areas. Seismic profiles were made to
depths in excess of 500 m with good resolution by
using a kilojoule sparker. The seismic profiles showed
that the subsurface formations are extensively
folded and that the structural fabric trends about

 

GEOLOGICAL SURVEY RESEARCH 1975

N. 5° W. In one area, where, interaquifer leakage of
saline water has occurred, the seismic record indi—
cated the presence of high-angle fractures with little
vertical displacement. It is not known Whether the
interaquifer leakage is the result of these fractures
or if other mechanisms are involved.

Direct-current resistivity measurements were
made in two small alluvial valleys in eastern Wyo-
ming to determine alluvium characteristics and
ground-water potential. Schlumberger depth sound-
ings by W. J. Headand R. W. Knottek in the Beaver
Creek valley in Weston County have resistivity
values ranging from 0.7 ohm—m to 5.5 ohm-m. Un-
usually low values are attributed to montmorillonite
clay weathering products which contain water high
in dissolved salts. Small resistivity changes noted in
each of the soundings suggest a similarity of the
grain size, moisture content, and composition of the
sediments. The water-yielding potential of this ma-
terial is virtually nonexistent. Depths to the consoli-
dated Pierre Shale of Cretaceous age range from 11
to 57 m. Results at one site were confirmed by auger
test drilling.

Soundings of the alluvium in the Horse Creek val-
ley in Goshen County have resistivity values ranging
from 30 ohm-m to 74 ohm-m. Initial interpretation
indicates the higher values to be associated with
clay-free gravels containing freshwater. Depth of
alluvium to the Brule Formation of Oligocene age
ranges from 9 to 22 m. The Brule is a fairly conduc-
tive clay-rich siltstone layer that contains large
quantities of freshwater in zones of secondary
porosity.

Underground waste disposal

R. M. Waller reported that injection of brine into
a new disposal well below a depth of 366 m near
Seneca Lake in New York was started by a salt-
mining company in late 1974. A network of existing
wells and streams was selected to monitor the chemi-
cal composition of the overlying shallow freshwater
aquifer. The monitoring program was complicated by
a 37,900-m3 spill from a brine pond a month prior to
the start of injection. The spill, however, demon-
strated the movement of brine from the pond area to
one of the monitor wells. Previously observed varia-
tions in chloride concentration of the shallow ground
water were probably caused by similar pond leakage
or spills.

Ground-water movement in fractured bedrock

Ground-water circulation in shallow bedrock units
consisting of sandstone, limestone, shale, claystone,

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

coalbeds, and underclays of the Conemaugh and Mo-
nongahela Groups of Pennsylvanian age in Allegheny
County, Pa., is controlled chiefly by joint and frac-
ture systems and to some extent by bedding planes.
Joint and fracture systems of these bedrock units
commonly have limited hydraulic connection, and
although the relative rates of ground-water move—
ment in these units have not been determined, the
units are generally considered to have low hydraulic
conductivity. According to Seymour Subitzky, in
areas where these units are underlain by mined-out
parts of the Upper Freeport and Pittsburgh coal-
beds, subsidence fissures resulting from mine-roof
collapse transect the joint and fracture systems of
the overlying bedrock units. Although soil particles
commonly fill the upper segments of these fissures, it
is believed that they remain open at depth. Where
hydraulic connection between these fissures and the
joint and fracture systems occurs, ground-water cir-
culation in the bedrock increases. Locally, the greater
hydraulic connection in these units has captured flow
that supported some wells and springs. Where hy-
draulic connection of fissures with joint and fracture
systems occurs in bedrock units overlying mined-out
areas in the county, ground-water inflow to mines
tends to be enhanced and contributes to mine flood-
ing. Where mine flooding occurs and remains una-
bated in above-drainage and unsealed mines, acid
mine-water discharge to streams is increased.

New tritium data reduce estimates of ground-water velocity

From 1966 through 1970, USGS scientists sam-
pled and tested tritium concentrations of well waters
collected along two traverses extending from the
west side of the San Joaquin Valley, Calif., across the
valley trough into the recharge area. J. F. Poland
and G. L. Stewart (1975) summarized the findings
and concluded that ground-water velocities are less
than one-eighth as rapid as those reported by others
in an earlier paper based on 1963 sampling for ther-
monticlear tritium analysis.

SURFACE-WATER HYDROLOGY

The objectives of research in surface-water hy-
drology are to define the magnitude and variation of
streamflow in time and space, both under natural and
manmade conditions, to understand the flow process
in stream channels and estuaries, and to define the
rates of movement and dissipation of pollutants in
streams.

 

181

Hydraulic and hydrologic modeling

V. R. Schneider used a theoretical potential-flow
model to estimate more accurately the length along
which losses are computed in approach sections to
highway encroachments. The contracted—opening
method yielded more accurate estimates of discharge
and of backwater when a more accurate estimate of
length was used. An improved method of estimating
energy loss in the expansion reach also was devised.

M. E. Jennings reported the development of com-
puter models of surface-water systems. Those for
stream-quantity analyses include streamflow and
reservoir-routing programs, stream-aquifer interre-
lationships, reservoir-systems analyses, sediment-
transport computations, and data—management rou-
tines. Computer models for stream quality include
unsteady-state DO analyses for streams, steady-state
estuarine DO analyses, and BOD analyses.

A daily-flow model was developed for reproducing
historical flow data in the Cape Fear River basin,
North Carolina, according to F. E. Arteaga. With a
slight modification of input parameters the model
can simulate daily flows at any point along the main
channels, both under present conditions and with
proposed reservoirs in place.

Applications of dye tracing

Dye tracing was used by L. A. Wagner and P. H.
Hamecher to define the dispersion pattern and time
of travel of effluent discharged into Cayuga Inlet at
Ithaca, N.Y. The dye (Rhodamine—WT) was injected
into the outfall pipe from the Ithaca sewage-treat-
ment plant. Dispersion in the inlet was monitored
by a fluorometer in a boat. At the end of 4 d the dye
had dispersed as far as 1.6 km.

E. R. German measured the travel time of soluble
substances in a 56-km reach of Shades Creek in J ef-
ferson County, Ala., using Rhodamine-WT dye.
Stream discharge ranged from about 110 1/ s at the
upper end of the reach to 650 US at the lower end.
Travel time for the entire reach was 233 h for the
leading edge of the dye cloud and 260.5 h for peak
concentration. Velocities ranged from 0.13 km/h
upstream to 0.37 km/h downstream below substan«
tial waste-water inflows.

A. O. Westfall and E. E. Webber measured disper-
sion characteristics and travel times of potential
point-source pollutants in a 17 O-km reach of the Tus-
carawas River above its confluence with the Wal-
honding River in Ohio. The fluorescent-dye-tracer
technique was used. For the whole reach, and at
stream discharges near 50 percent on the duration

182

curve, the travel times for the leading edge of the
dye cloud and for the peak concentration were 119
and 137 h, respectively. This information will be
used by the Ohio Environmental Protection Agency
to estimate DO recovery rates and travel times of
accidental pollutant spills.

Estimating streamflow characteristics from channel size

Regional relations between streamfiow character-
istics and stream-channel size offer a promising al-
ternative to available methods of estimating flow
characteristics for ungaged sites, particularly in
semiarid regions. Some agreement on standardiza-
tion of methods was reached in April 1974 among
about a dozen investigators. A summary of recom-
mended practices with respect to flood characteristics
was reported by H. C. Riggs (1974) .

Reliability of flow estimates from channel size de-
pends partly on the user’s ability to recognize a suit-
able channel reach and the reference levels in that
reach. K. L. Wahl set up a test in northern Wyoming
to determine how consistently trained individuals
could measure channel size for three different refer-
ence levels. Seven participants independently visited
22 sites and measured channel dimensions in sections
of their choosing. Assuming the functional relation
between a discharge characteristic, Q, and channel
width, W, is log Q=f(1.5 log W) and that the aver-
age log W from seven measurements is the best esti-
mate of log W at a site, an average standard error
of about 30 percent for discharge measurements was
attributed to differences in width measurements
alone.

E. R. Hedman measured width and average depth*

of the active channel cross sections to define rela-
tionships for mean annual runoff in six hydrologic
regions in the Missouri River basin. Hedman has
defined the relationship of 10-yr peak discharge to
channel size for five hydrologic regions. Standard
errors of these relationships range from 30 to 35
percent.

L. M. Shown related flood-peak characteristics to
width and depth of ephemeral stream channels in
southwestern Utah, northwestern Arizona, and
southeastern Montana. For a given width, the peaks
on Montana streams are an order of magnitude
smaller than those on Utah and Arizona streams.

Statewide relationships for estimating peak-flow
characteristics and mean annual flow from channel
width have been developed by H. W. Lowham for
Wyoming streams. The standard error of 47 percent
is smaller than that for relationships estimated from
basin characteristics.

 

GEOLOGICAL SURVEY RESEARCH 1975

A modified slope-area method for computing discharge in

natural channels

Discharge of a stream may be computed from the
slope of the water surface, the cross-sectional area,
and an estimate of the roughness coeflicient. This,
the slope-area method, is Widely used to compute
flood-peak discharges from high-water marks. Relia-
bility of a computed discharge depends largely on the
roughness coefficient, which must be estimated. An
analysis by H. C. Riggs showed that results of com—
parable accuracy can be obtained from area and slope
alone in natural channels; a roughness coefficient is
not needed because roughness and slope are related.

Velocity pulsation measurements

B. L. Neeley, Jr., reported that velocity measure-
ments were made on the Mississippi River at Baton
Rouge, La., when the discharge was 20,600 m3/s.
Velocity 2 m below the water surface was recorded
continuously for 5 h at two locations. From these
records, average velocities were computed for 5-min
intervals beginning every 20 s during the 5-h period.
Average velocities during the first 20 s, 40 s, 60 s, 80
s, 2 min, and 3 min of each 5—min interval also were
computed. Standard errors of 3.1, 2.5, 2.2, 1.9, 1.5,
and 1.0 percent, respectively, were obtained when
the partial-period mean velocities were related to the
5-min mean velocities.

A mathematical model for density-stratified flows

E. R. Holley developed a mathematical model for
computing steady-state flows in a rectangular chan-
nel connecting two stationary bodies of water with
different elevations and densities. The model solves
appropriate equations of motion for each of three
possible regimes (one-layer undirectional flow, ar-
rested-wedge undirectional flow, and two-layer two-
way flow) and chooses a correct solution for given
boundary conditions by a sequential elimination
process. Numerical solutions of flow through culverts
of the Great Salt Lake Causeway are in acceptable
agreement with 49 field measurements. The com-
puted flow is sensitive to errors in measurement of
water-surface elevation.

Thermal loading models of natural streams

Nobuhiro Yotsukura (USGS) and W. W. Sayre
(Univ. of Iowa) found that the steady-state two-
dimensional mixing equation, derived earlier by
Yotsukura and E. D. Cobb (1972) for uniform flows,
can be extended to nonuniform flows with a small
modification. Use of a natural coordinate system
with the longitudinal axis parallel to a curved stream

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

axis provides a distance-correction coefficient, rang-
ing around unity, that is entered into the equation.
This analytical work explains why closed—form solu-
tions to the YotsukuraCobb equation agree with
tracer and thermal data. for two-dimensional mixing
observed in a number of meandering natural streams.

Levee erosion

The relative amounts of levee erosion caused by
natural forces (wind—generated waves and floodflows)
and by small-boat traffic were studied in the Sacra-
mento—San Joaquin Delta, Calif., by J. T. Limerinos
and Winchell Smith (1975) . In- the narrow channel of
Georgiana Slough, which is subject to winter flood-
flows and to heavy summer boat traffic, about 70
percent of the energy dissipated annually against the
levee was attributed to tractive stress, about 20 .per-
cent to boat-generated waves, and about 10 percent
to wind-generated waves. In False River, a channel
subjected to continual tidal action but relatively un-
affected by floodflows, energy dissipated by boat-gen-
erated waves was shown to range from about 45 to
80 percent of the total, depending on wind-movement
assumptions.

FIood-hydrograph synthesis

G. S. Craig, J r., and J . G. Rankl developed a dimen-
sionless hydrograph of storm runoff from 298 hydro-
graphs on 28 small drainage basins in Wyoming.
They tested its reliability by synthesizing hydro-
graphs from peaks and volumes of observed events,
including some events not used in its derivation, and
by comparing the synthesized with the observed hy-
drographs; a close agreement was found. They also
developed (1) equations for estimating flood-peak
discharges and flood volumes (at recurrence intervals
of 10, 25, 50, and 100 yr) from drainage-basin char-
acteristics and (2) a relationship between flood vol-
ume and peak discharge. These. relationships can be
used with the dimensionless hydrograph to estimate
design hydrographs at ungaged sites on Wyoming
streams draining less than about 28 km2.

Predicting summer runoff in the northern Cascade Range,
Washington

L. A. Rasmussen and W. V. Tangborn (1976) de-
veloped a hydrometeo-rolo-gical method for predicting
summer runoff from drainage basins in the northern
Cascade Range. The method, based on a linear rela-
tion between winter precipitation and annual runoff,
relates streamflow for a season beginning on the day
of prediction to the spring storage (including snow,
ice, soil moisture, and ground water) on that day.

 

183

The spring storage is inferred from an input-output
relationship based on winter precipitation and win-
ter runoff. Some advantages of the method are: (1)
Monthly distribution of the predicted summer run-
off can be computed; (2) the altitude distribution of
estimated potential runoff or storage can be inferred;
(3) only existing low-altitude runoff and precipita-
tion stations are used; and (4) snow surveys are not
needed.

CHEMICAL, PHYSICAL, AND BIOLOGICAL
CHARACTERISTICS OF WATER

Hydrogen-ion concentration in southern New Jersey stream

Fishkills in Oyster Creek, near Waretown, N.J.,
are attributed by J. C. Schornick, J r., to rapid de-
creases in pH levels from anormal of about 4.2 to
about 3.6. These decreases occur during periodic
flushing of a surrounding swamp but are not related
necessarily to rainfall; the time interval between
rains seems to be more important than the amount
of rain. There is a direct linear relationship between
the swamp and the stream pH levels. The acidity is
probably the result of the oxidation of sulfides to
sulfate in the open waters of the swamp.

Nitrification in acidic streams

Results of studies in southern New Jersey by
J. C. Schornick, Jr., and N. M. Ram showed that
many streams that receive secondary sewage effluent
are characterized by pH levels of 4 to 7. Because ni-
trification occurs ideally at a pH level of 8.5 and de-
creases rapidly at pH levels below 7.0, four acidic
streams were investigated to determine the effect
of stream acidity on nitrification. The effluent pro-
vided enough buffering capacity to enable nitrifica-
tion to occur, although the degree of nitrification
varied considerably from one stream to another. The
NH+, N02: N03—, and bacteria curves showed that
growth and decay increased with distance down-
stream.

Reaeration measurements in streams

R. E. Rathbun, D. J. Shultz, and D. W. Stephens
used a nonradioactive-tracer technique to measure
reaeration coefficients of a reach of West Hobolo-.
chitto Creek near Millard, Miss. Rhodamine-WT
dye was used as the dispersion and dilution tracer.
Ethylene was used as the tracer gas, and concentra-
tions (pg/l) in water samples were determined by
gas chromatography. Measured reaeration coeffi-
cients were within the range of coefficients predicted
by other equations.

184

Nuclear magnetic-resonance spectroscopy of humic acid
derivatives

Proton and carbon-13 nuclear magnetic-resonance
spectroscopy has been used extensively for the eluci-
dation of the chemical structure of organic com-
pounds. In previous attempts to measure the nuclear
magnetic-resonance spectra of humic acids, the in-
vestigators were unable to obtain spectra measure-
ments because free radical concentrations in the
preparations broadened absorption peaks so much
that none of the peaks were detectable. In order to
eliminate this problem R. L. Wershaw, D. J. Pinck-
ney, and S. E. Booker prepared the methyl esters
of the humic acid fractions, using a new methyla-
tion procedure which they developed. The proton
nuclear magnetic-resonance spectra of these deriva-
tives have well-defined absorption lines which can
be used for structural interpretation. Also, prelimi-
nary results strongly indicate that it is possible to
obtain measurements of carbon-13 spectra.

Sacramento River water-quality investigation

As part of an intensive water-quality study of the
Sacramento River in California, physical, chemical,
and biological constituents were measured at three
locations at a site on the river. Measurements made
periodically over two 24-h periods included those
for water temperature, DO, pH, specific conduct-
ance, selected major ions, plant nutrients, and phyto-
plankton.

L. J. Britton and R. C. Averett reported that con-
stituent concentrations were often erratic, but they
did not differ significantly between locations during
the same time period nor with depth at individual
locations.

Regional distribution of nitrogen, phosphorus, and specific
conductance studied in Florida surface waters

M. I. Kaufman and L. J. Slack mapped chemical-
type and regional-distribution patterns of specific
conductance of Florida surface waters (Kaufman,
1972; Slack and Kaufman, 1973). The five chemical
types mapped in terms of dominant cations and
anions are: (1) Calcium and magnesium bicarbo-
ate, (2) sodium bicarbonate and chloride, (3) mixed
type, (4) sodium chloride, and (5) calcium and
magnesium sulfate. Most surface waters in the State
are of type 1 or type 3.

In studying nitrogen, phosphorus, and organic
carbon distribution in Florida surface waters, Kauf-
man and J. E. Dysart observed that organic nitrogen
is the dominant nitrogen species in most surface
waters, whereas nitrate nitrogen is dominant in

 

GEOLOGICAL SURVEY RESEARCH 1975

shallow ground waters. Other studies showed rain-
fall and atmospheric fallout to be important sources
of both nitrogen and phosphorus.

Chemical and biological effects of sanitary landfill leachate

Although the sanitary landfill serving the towns
of Catskill, Athens, and Cairo, N.Y., is operated
carefully, leachate from the landfill is believed by
T. A. Ehlke to have caused profound changes in the
biology of a nearby stream, Bell Brook. The benthic
invertebrates, Ephemeroptera, Trichoptera, and
Heterodonta, that were in the affected reach are be-
ing replaced by Naididae and Tendipedidae. Con-
centration-s of oxygen, nitrogen, and carbon and
levels of pH in the affected reach of the stream have
changed very little. The benthic invertebrate types
in the stream are determined by the content of cer-
tain trace elements in ground water below the
streambed. Iron and manganese are believed to be
the most important trace elements affecting benthic
invertebrates.

Inhibition of microbial plugging of laboratory columns

G. D. Ehrlich investigated the causes of plugging:
of experimental sand columns in the laboratory;
plugging commonly occurs even when deionized
water passes through washed sand. Certain bacteria
and fungi can grow in these extremely dilute solu-
tions and are sustained by traces of nutrients de-
rived from the laboratory atmosphere and experi—
mental apparatus. Plugging does not occur if ade-
quate concentrations of mercury ions are present.
Low levels of mercury (5X10—5M Hg”) caused se-
lective inhibition of slime-forming organisms,
whereas mercury-tolerant organisms multiplied in
large numbers in the columns containing deionized
water. Plugging did not occur until the mercury
concentrations were less than 5><10—7 M.

Mathematical model of a small stream

Chloride, sodium, and stable strontium were in-
jected for 3 h at a constant rate into Uvas Creek,
Calif, to determine transport processes in a small
mountain stream. S. M. Zand, V. C. Kennedy,
G. W. Zellwege-r, and R. J. Avanzino reported that
comparison of field results with a simplified mathe-
matical model of the experiment indicated the domi-
nance of convection in the behavior of solutes in the
stream. Concentrations of chloride and sodium can
be closely simulated by the model, but strontium
concentration cannot.

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

Specific surface area as an index of reactivity

D. W. Brown (D. W. Brown and J. D. Hem, 1975)
used several laboratory methods to measure the
specific surface areas of four different materials—
a sand consisting mainly of feldspar grains, a vol-
canic ash, a kaolinitic clay, and a montmorillonite.
The areas, ranging from 550 to 0.5 mz/g, correlated
well with the cation-exchange capacity of the ma-
terial. It seems possible that surface-area measure-
ments will provide a useful index of the extent to
which river sediments and surfaces of subsoil and
aquifer material may react with and retain or de-
crease movement of pollutants in introduced waste.

Prediction of stream temperatures in New England

G. D. Tasker and A. W. Burns (1974) have fitted
periodic stream-temperature data from 27 stations
in New England to a harmonic function with a
period of less than 365 d to account for the winter
period when stream temperatures are at or near 0°C.
Regression analyses were used to relate character-
istics of the harmonic function to mean basin alti-
tude and station latitude. These generalized equa—
tions make possible the prediction of harmonic mean
stream temperature and streamflow at any site in
New England. Such information may be useful for
general-purpose planning, reconnaissance, and site-
comparison studies.

Stream-temperature study in Indiana

W. J. Shampine reported that periodic tempera-
ture data collected by the USGS since 1950 and by
the Indiana State Board of Health since 1957 are
being analyzed, using a simple harmonic-curve-fit—
ting procedure. The percentage of stream-tempera-
ture variability explained by the harmonic function
exceeds 80 percent for 293 of the 304 stations.

The Indiana State Board of Health collects tem-
perature data every 2 weeks, whereas most USGS
data are collected monthly. Comparison of the har—
monic mean, amplitude, and phase coefficient, cal-
culated using 43 stations common to both sources
and having overlapping periods of record, showed
no statistically significant differences that could be
attributed to the difference in sampling frequency.
On‘ individual streams, however, the calculated
values derived from the two harmonic relationships
may have more than a 10-percent difference in har-
monic mean ‘and amplitude, particularly in streams
near large urban areas.

 

185

RELATION BETWEEN SURFACE WATER
AND GROUND WATER

Stream-aquifer modeling

Twenty-three sites on the alluvial flood plains of
five major tributaries to the Ohio River in Kentucky
were selected by P. D. Ryder (1974, 197 5) in a study
to determine aquifer characteristics. A pair of ob-
servation wells was installed in the alluvium at each
site, and recorded ground-water levels resulting from
the passage of a flood wave in the river were analyzed
by computer to determine the ratio of transmissivity
to storage coefficient. This ratio was helpful in se-
lecting transmissivity and storage coefficients to be
used in an iterative digital model together with
streambed thickness and hydraulic conductivity,
water levels in the river, and location of bedrock
valley walls. The models were verified by comparing
computed ground-water levels of a passing flood wave
in the river with observed data..

The methods, successful at only three of the sites,
resulted in the following values: The ratio of trans-
inissivity to storage coefficient ranged from 4.5X104
to 3.2><106 mZ/d; transmissivity from 9.3><1Ol to
2.2X102 mz/d; storage coefficient ranged from 3X
10—5 to 6X10—3; streambed hydraulic conductivity
ranged from 1.6X10—4 to 1.0><10-1 m/d with a
streambed thickness of 1 m; and recharge from the
bedrock valley wall ranged from 0 to 1.3x 10—2 m/d.
Analyses were unsuccessful at 20 sites because (1)
one or both wells did not penetrate aquifer material,
(2) there was significant aquifer inhomogeneity be-
tween wells, or (3) a combination of very low storage
coefficient and large transmissivity values prevented
the determination of unique, best-fitting, theoretical
type curves.

Bank storage

A significant volume of water is stored in the
banks of Franklin D. Roosevelt Lake in northeastern
Washington. Preliminary results from a computer
model developed by T. H. Thompson for determining
bank-storage volumes indicate that an additional 5
to 10 percent of the usable storage is in the banks.
The usable storage is 6.25><109 m3 between the nor-
mal operating-stage elevations of 368 m and 393 m.

The parameters of the model are being further re-
fined by comparing the model results with water-
budget residuals. The model will be used to determine
the volume of additional water from bank storage
that may be available under various operating condi-
tions at Grand Coulee Dam. The water may be used

186

for on-site power generation and downstream bene-
fits such as irrigation and power generation.

The model may be modified for use at other reser-
voirs in the Pacific Northwest where bank storage
may be significant.

Ground-water emergence in trout-spawning areas in spring-fed
ponds

In a study of the hydrology of spring-fed ponds
and the hydrologic effects of trout-habitat improve-
ment practices, W. J. Rose (USGS) and R. F. Carline
(Wisconsin Department of Natural Resources)
found a correlation between the location of redds
(brook-trout spawning areas) and the rate of
ground-water emergence. A portable device for
measuring the rate of ground-water emergence
through 0.255 m2 of pond-bottom area was devel-
oped. Rates of ground-water emergence, which were
determined by placing the device over redds, were
found to be as much as 15 times greater than rates
of ground-water emergence from nearby areas
where there were no redds. These findings suggest
that, in ground-water discharge areas, local hetero-
geneity of aquifer materials strongly influences the
movement of ground water to points of emergence
and that brook trout select places having high rates
of ground-water emergence as sites for redd con-
struction.

Surface-water-ground-water relationships in the Springfield,

Missouri, area

Some streams in the Springfield, Mo., area have
interrupted flow during the summer. To determine
whether the water disappears into the channel fill
and moves downstream within the fill or is lost to

the underlying limestone, John Skelton and L. F.
‘ Emmett made seepage runs during the winter when
the streams flow without interruption. Although
winter base flows were large during the seepage runs,
losses in certain stream reaches were identified and
found to flow into the underlying limestone aquifer.
These reaches are potential sources of ground-water
contaminatic‘m.

Artesian-aquifer recharge causes contamination of ground water

Results of a study by R. E. Krause indicate that
the Withlacoochee River, flowing over a limestone se-
quence north of the city of Valdosta in southern
Georgia, recharges the principal artesian aquifer
with more than 850 l/s of water. During periods of
low flow, the entire flow of at least 708 l/s discharges
into the limestone aquifer. A southeasterly flow path
of recharged ground water is indicated by measure-

 

GEOLOGICAL SURVEY RESEARCH 1975

ments of water levels and field determinations of pH
and conductance in water from a network of wells
surrounding the recharge area. Downstream, Where
the head relationships are reversed, the aquifer dis-
charges as much as 2,4071/s of water to the river.
North of Valdosta, where flow is not maintained
during periods of low flow, treated and untreated
sewage efl‘luent is discharged into the river and is
undiluted until base flow from a shallower aquifer
and the artesian aquifer enters the channel. Wells
tapping the aquifer in the flow path of the locally
recharged water are abandoned because of high
organic color, which cannot be economically removed.

Decreasing ground-water recharge from canals in the Miami
Springs-Hialeah area, Florida

F. W. Meyer (1972) and~W. L. Miller found that
infiltration from the Miami Canal system to major
well fields in the Miami Springs-Hialeah area is de-
creasing as a result of a buildup of fine-grained sedi-
ments. Measurements of seepage losses from canals
closest to the well fields during May 1973 indicated
that only 50 percent of the average daily pumpage
(4.5X105 m3) was contributed by the canals. This
was a decrease of about 8 percent over a 5-yr period.
Ways to improve infiltration and prevent further de-
cline in the water table are being investigated.

SOIL MOISTURE

An understanding of soil-moisture retention and
movement is vital to the knowledge and control of
our environment. USGS scientists are conducting
field and laboratory investigations of the mech-
anisms involved in infiltration, evaporation, transpi-
ration, and movement of water to the water table.

A soil-moisture model for predicting soil-water storage and use

Because of great fluctuations in annual and sea-
sonal precipitation patterns, the use of soil-moisture
models may permit closer approximations of soil-
moisture storage and use than do periodic seasonal
measurements of soil moisture. The model previous-
ly proposed by I. S. McQueen and R. F. Miller
(1974) for approximating soil-moisture character-
istics from limited data was further tested by
McQueen, Miller, and F. A. Branson, utilizing
moisture-content and moisture-stress data acquired
from intensive field studies. Results indicate that
water is adsorbed to the surface of soil particles as
films and that these films become thicker as the soil
becomes more moist. Water retained in contact
angles by capillary forces apparently adheres to the
adsorbed film's. Evidence of capillary moisture ad-

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

hering to adsorbed moisture was obtained only at
sites where capillary moisture was at equilibrium
with a water table. Where no water table was pres-
ent, evidence indicated that moisture was adsorbed
only as films. This was true even at levels of stress
usually associated with the capillary moisture-reten-
tion range. Field evidence of capillary rise was lim-
ited to somewhat more than 2 m. This coincides
with the level of stress where quantities of water
present in either the adsorbed or capillary state are
equivalent. This equilibration occurs at a soil-mois-
ture stress of approximately 2.24 m of water (22
kPa).

Evapotranspiration losses from stream channels

Phreatophytes along almost 2,000 km of stream
channels in central Arizona were mapped to provide
estimates of present and future evapotranspiration
losses from these channels. The estimate of evapo-
transpiration will be based on a method of integra-
tion of the phreatophytes. Using the integration
method for a reach of channel along Oak Creek,
T. W. Anderson found that the estimate of consump-
tive use along the channel was in good agreement
with that determined by a study of the base flow
of Oak Creek near the Cornville gaging station.
Several other sites are being investigated to deter-
mine the utility of the integration method. The base-
flow analysis will be used again to check the results
of the integration method.

Analytical solution for evapotranspiration rate from ground

water

J. F. Daniel developed a type-curve solution for
the constant rate of ground-water withdrawal by
evapotranspiration; this is an extension of the work
by M. I. Rorabaugh (unpub. data, 1975) . The method
uses streamflow hydrographs transformed to dimen-
sionless time. Application of the method to “a 1963
segment of the hydrograph for Indian Creek near
Troy, Ala. (Coastal Plain), resulted in an evapo-
transpiration rate slightly less than 5 mm for a 30-
d period during the months of May and June.

Use of reflectivity coefficient for heat budget in watershed model

J. F. Turner reported that a watershed model is
being calibrated for several streams in west-central
Florida. As in most watershed models, a measure of
daily potential evapotranspiration is used as input.
For many models, pan evaporation is normally used
as a measure of potential evapotranspiration. How-
ever, for west-central Florida, only meager pan-
evaporation data exist and therefore daily evapo-
transpiration values were calculated by use of a

 

187

computer program based on H. L. Penman’s (1948)
equations.

In Penman’s method, daily evaporation and a daily
heat budget are required for computing potential
evapotranspiration. Calculations of a daily heat bud-
get require a reflectivity coefficient which is the
ratio of reflected incoming radiation to total in-
coming radiation. The reflectivity coefficient, or
albedo, is primarily a function of reflecting char-
acteristics of the basin surface, angle of the rays
of the Sun to the surface, and wavelength of the in-
coming radiation. Because of the regional variation
of the surface, the reflectivity coefl‘icient must be
determined experimentally.

A reflectivity coefficient of 0.15 gave good results

. for the Tampa Bay area. The value was obtained by

adjusting values of the reflectivity coefficient until
simulated evapotranspiration agreed with basin
evapotranspiration. Basin evapotranspiration was
computed from long-term runofl" and rainfall rec-
ords.

A mass-transfer equation calibrated by pan evaporation in
evaporation studies ‘

Use of some mass-transfer equations for the pur-
pose of measuring evaporation requires the deter-
mination of a coefficient. This can be done by
measuring evaporation by the water-budget method
or the energy-budget method while collecting the
necessary data for the mass-transfer equation. How-
ever, determining the coeflicient by the water-budget
or energy-budget method is expensive and slow.
Studies of Lake Michie and Hyco Lake, in North
Carolina, indicate that pan-evaporation data may
be used to determine the coefficient at less cost.
G. L. Giese noted that although pan data converted
to lake evaporation by a pan-to-lake coefficient do
not give reliable results on a daily or monthly basis,
they do provide reliable estimates on an annual basis.
A pan-to-lake coefficient of 0.72“ was found to be
generally applicable in the Piedmont area of North
Carolina.

Using lake evaporation data determined from the
water-budget method, a coefficient was determined
for the mass-transfer equation and compared to
the coefficient determined from pan data. The values
agreed within 12 percent, which is considered to be
in the allowable error for evaporation studies in the
Piedmont area. Hence, lake evaporation as deter-
mined over a long time interval (at least 1 yr) may
be determined by multiplying nearby pan evapora-
tion by the proper pan-to-lake coefficient (0.72 in the
Piedmont section of North Carolina).

188

Using Harbeck’s (1962) mass-transfer equation
E=Nu(eo_ea)9

in which E=evaporation, in inches per day;

N =a coeflicient of proportionality, called
the mass-transfer coefficient;

u=wind speed, in miles per hour, at some
height above the water surface; a
numerical subscript, if used, indicates
the height in meters;

eo=saturation vapor pressure in milli-
bars, corresponding to the tempera-
ture of the water surface;

ea: vapor pressure of the air, in millibars;
a numerical subscript, if used, indi-
cates the height in meters,

the lake evaporation is set equal to the sum of the
daily expressions of Nu (co—ea) over the same time
interval. The coefficient N is the only unknown in
this equation. Daily values of wind speed and vapor
pressures were generated from measurements of
wind speed 2 m above the water surface, water
temperatures, and wet- and dry-bulb air tempera-
tures. This method of calibration yielded an N co-
efficient of 0.000187 for Hyco Lake as compared to
a coefficient of 0.000167 derived from the water-
budget method of calibration. These two values are
in reasonably close agreement (12 percent) and are
considered equally accurate, but the pan-evaporation
method of calibration is both much cheaper and
faster.

EVAPOTRANSPIRATION

Evapotranspiration, the conversion by plants of
water to vapor that is mixed with the atmosphere,
accounts for the expenditure of approximately 70
percent of the 760-mm average annual precipitation
in the conterminous United States. Because a large
part of our water resource is being lost by evapo-
transpiration, measurements of the losses are very
important for planning purposes.

Most of the significant results of evapotranspira-
tion studies during the past year were from studies
of stream channels and ground—water storage areas.
Indirect methods of measurement, such as the water
budget, were used in these investigations. Studies of
indirect methods are continuously being made in
order to improve their accuracy and to reduce their
cost.

 

GEOLOGICAL SURVEY RESEARCH 1975

Relation of consumptive-use coefficient to the description of
vegetation

The consumptive-use coefficient for the Blaney-
Criddle evapotranspiration equation depends on vege-
tation characteristics. According to R. C. Culler,
R. L. Hanson, and J. E. Jones, the basis for this rela-
tionship was found to exist when the measured evap-
otranspiration for the Gila River Phreatophyte Proj-
ect in Arizona was compared to the conventional
botanical survey. The survey includes species identi-
fication and canopy measurements which represent
an integration of growth and transpiration charac-
teristics during the life of a plant. Average seasonal
coefficients have been calculated, but application of
these coefl‘icients is restricted to areas having similar
seasonal climatic and enviromnental conditions to
those of the project area.

A densitometric interpretation of repetitive color-
infrared photography was developed for the project
area to describe the spatial and temporal variability
in foliation. The photographic measure of vegetation
was related to the consumptive-use coefficient to pro—
vide a method of defining the seasonal variability in
the coefficient by contemporary observations.

LIMNOLOGY AND POTAMOLOGY

Lake reconnaissance

Lake-reconnaissance surveys provide baseline in—
formation, identify problems for more intensive
investigation, and form a basis for regional classifi—
cation of lakes.

Reconnaissance limnological surveys in Pennsyl-
vania at 52 recreational lakes were completed during
the months of July and August between 1971 and
1974. In addition to providing a baseline of informa—
tion for future hydrobiological investigations, the
data will allow the lakes to be classified as to condi-
tion in compliance with Section 314 of Public Law
92—500. According to J. L. Barker, the surveys have
disclosed that 18 of the 52 lakes display symptoms:
of, or the potential for, an enriched status. Because
eutrophication of these lakes is due to natural and
nonpoint sources of enrichment, control and restora-
tion will be difl‘icult.

Reconnaissance surveys by M. V. Shulters, Antoni-
us Laenen, and J. H. Robison of 23 lakes in the high
Cascade Range of northern Oregon showed the lake
water to be of very high quality. The lakes range in
size from 0.75 to 180 ha and dissolved-solids content
is less than 60 mg/l; dissolved-solids content of 14 of.
the lakes is less than 20 mg/l. Light transparency,

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

measured by a Secchi disk, exceeded that of many
smaller lakes; a maximum reading of 12 m was re-
corded in Lost Lake near Mount Hood. Lake sedi-
ments generally were unconsolidated and supported
very little bottom vegetation. No fecal coliform bac-
teria were found in any of the lakes surveyed. Dur-
ing the September and October sampling period,
thermal stratification was significant in only three of
the largest lakes. The lakes surveyed are typical of
many Cascade Range lakes; they were formed large-
ly as a result of glacial or volcanic activity and are
used primarily for public recreation. The several
lakes that are protected Within Portland’s Bull Run
watershed probably will remain in their present con—
dition, but other Cascade Range lakes may receive
greater recreational use in the future, which may
result in water-quality changes.

G. A. McCoy collected chemical and physical data
on Redoubt, Green, and Blue Lakes near Sitka, on
Swan and Spurt Lakes near Petersburg, and on Os-
prey Lake near Port Walter, all in southeastern
Alaska. The lakes are oligotrophic and, except for
Redoubt Lake, conductivity was less than 50 [1.th
at 25°C. Nitrogen content was low and phosphorus
content was generally less than 0.01 mg/l. DO ex-
ceeded 50-percent saturation at the bottoms of all
lakes except Redoubt, which is meromictic. The up-
per 100 m of Redoubt Lake is freshwater and the
lower 200 m is saltwater. The lower layer (monimo-
limnion) is anoxic. The upper layer (mixolimnion) of
Redoubt Lake is well oxygenated and much higher
in conductivity and dissolved-solids concentrations
than the other lakes. It is high in sodium and chlor-
ide, probably owing to upward diffusion from the
monimolimnion. Spurt, Swan, Blue, and Green Lakes
have calcium bicarbonate type waters of very similar
chemical composition. Osprey Lake, however, has a
predominantly sodium chloride water, probably be-
cause of its high annual rainfall, low altitude, and
proximity to the sea.

Data for 76 lakes with surface elevations ranging
from 1,698 to 3,613 m were collected in the Front
Range Urban Corridor, 0010., between lat. 38°37’30”
N. and lat. 39°22’30” N. The lakes varied from stably
stratified to thoroughly mixed, and water tempera-
tures ranged from 6° to 24°C when sampled in mid-
summer. Secchi-disk transparency measurements
were 1.2 m or less in six of the lakes but as much as
5.0 m in Mesa Reservoir. D. B. Adams reported that
most of the lakes have water of good chemical quali-
ty. The range in specific conductance was from 25
,umho/cm at 25°C in Big Tooth Reservoir to nearly

 

189

1,100 pmho/cm at 25°C in an unnamed lake and pH
levels ranged from 7.6 in Big Tooth Reservoir to 10.6
in Big Stratton Reservoir. DO as percent of satura-
tion ranged from 68 percent in Big Johnson Reser-
voir to 186 percent in an unnamed reservoir.

Chlorophyll a concentration and phytoplankton
were sampled in 13 of the larger lakes and reser-
voirs. Sixteen different genera of algae were identi-
fied as dominants or codominants in the lakes
sampled; the most common were Anacystis, Synedm,
Cyclotella, 0601182323, and Dinobryon. Algal concen-
trations ranged from 380 to 57,000 cells/ ml. All lakes
sampled were rated for degree of organic loading by
the algal index method of C. M. Palmer (1969). Only
one lake, at Broadmoor Country Club, showed evi-
dence of high organic loading on the basis of algal
samples.

Relation of ground water to lakes

A preliminary hydrologic classification of lakes in
the north-central United States was developed by
T. C. Winter. Several forms of factor analysis were
used to identify the independent factors that led to
the most hydrologically meaningful classification
system. In the principal component analysis, the first
five factors account for 80 percent of the variance in
the original 13 parameters. The loadings show factor
1 characterized by atmospheric water and chemical
parameters, factor 2 by streamflow parameters, fac-
tors 3 and 4 by parameters that are related to
ground-water flow, and factor 5 by overland runoff
parameters. Maps of each of the five factors show
distinctive patterns of areal variations within the
study area. The statistical analysis is based on a
random sample of 150 lakes.

Limnology of Lake Loiza

The chemical, physical, and biological characteris-
tics of Lake Loiza, in Puerto Rico, Were evaluated
during a 1-yr period by Ferdinand Quifiones-Mar-
quez. The quality of the water in the reservoir is
affected by partially treated sewage and agricultural
runoff. Total-nitrogen and total-phosphorus concen-
trations in the reservoir averaged 1.5 to 0.3 mg/l,
respectively. Dense blooms of water hyacinths
(Eichorm’a crassipes) occurred throughout the year.
Transport of sediments by tributaries to the reser-
voir decreased light penetration, limiting blooms of
microalgae. Phytoplankton communities were domi-
nated by Anacystics, Melosira, and Cyclotella. Com-
munity productivity in the reservoir, measured by
the diurnal oxygen curve, averaged from 3 to 12
g 02 m—3 d—l. The dominant zooplankters were

190

species of Macrocyclops, Paracyclops, Halicyclops,
and Moina. Vertical and diurnal fluctuations of the
zooplankton were affected by low DO concentrations.
DO varied seasonally with the intensity and magni-
tude of the lake turnover. During the low-flow sea-
son, most of the reservoir was anaerobic below 3 to
4 m. During the wet season, from September to
December, DO concentrations of 2 to 3 mg/l were
measured at depths of 10 to 12 m. Some thermal
stratification occurred in Lake Loiza. During the
winter months, top to bottom temperatures ranged
from 24.5° to 28.0°C. In the summer and during
high flows into the reservoir, nearly complete mixing
occurred, and water temperature averaged 29.0°C.
The bottom sediments of Lake Loiza contained an
average of 2,000 mg/kg of total nitrogen and 850
mg/kg of total phosphorus. Bottom sediments were
about 5 percent sand, 40 percent silt, and 55 percent
clay. Nearly 10 percent of the upper 30 cm of sedi-
ments was organic matter.

Limnology of Laguna Tortuguero

A 1-yr study of the chemical, physical, and
biological characteristics of Laguna Tortuguero,
in Puerto Rico, was started in July 1974 by
Ferdinand Quifiones-Marquez. The lagoon is a near-
ly freshwater body with an average specific conduc-
tance of about 2,500 ,umho/cm at 25°C and an aver-
age chloride concentration of 800 mg/l. The lagoon
is unstratified, has an average depth of about 2.5 m,
and is constantly mixed by winds. The bottom is
covered with a thick layer of sediment which is 6 to
8 m deep in some parts. The lagoon is affected by sea-
water flows from the zone of diffusion. Sea salts are
present in concentrations proportional to seawater,
but a canal discharges about 0.4 m3/s into the ocean,
maintaining a low salinity in the lagoon. The phyto-
plankton of the lagoon was dominated by Anacystis
and other blue-green algae. The bottom of the lagoon
was covered with a mat of periphyton, most of which
were diatoms. There were more than 50 species of
diatoms in the assemblage. The zooplankton was
dominated by species of Diaptomus, Testudinella,
Keratella, Diaphanosoma, and Ceriodaphnia. Total
nitrogen and total phosphorus concentrations in the
lagoon averaged 1.7 mg/l and 0.005 mg/l, respec-
tively.

Initial limnological observations of Raystown Lake

D. R. Williams observed that during the first few
months of water impoundment in Raystown Lake,
Huntingdon County, Pa., no significant thermal or
DO stratification occurred. At the time of these

 

GEOLOGICAL SURVEY RESEARCH 1975

observations the lake elevation was at 233 m, about
3 m below the winter-pool elevation of 236 m and
7 m below the recreational-pool elevation of 240 m.
Only in the upper, more shallow reaches of the 43-
km—lor g lake was there evidence of anaerobic condi-
tions on the lake bottom. In the deeper parts of the
lake, approximately 5.6 km upstream from the dam-
site, DO concentrations as high as 7.6 mg/l were
recorded on the lake bottom, 41 m below the surface,
indicating that there had been no extensive decom-
position of organic matter. Bacteriological data col-
lected on the lower 23—km reach of the lake indicated
very low concentrations of fecal coliform and fecal
streptococcus bacteria. High flows from the main
inflow feeding the lake increased the bacteria counts
considerably in the upper 21-km reach of the lake
but had little if any effect on‘the lower reach.

Diversity indices in water-quality studies

Diversity indices are used to summarize species-
abundance tables and some other characteristics of
biological systems. The most commonlyused diver-
sity index in water-quality studies is theone derived
from J. L. Wilhm’s and T. C. Dorris’ (1968) infor-
mation theory. Some shortcomings of using diversity
and redundancy, its associated parameter, as unique
indicators for the health of aquatic communities
were found by S. M. Zand. Redundancy, R, as defined
by Wilhm and Dorris (1966), is

Hmax;H

Hmax_Hmin

where Hmax and Hm,“ are maximum and minimum
diversity indices using the Brillouin formula, while
H is the diversity index using the Shannon equation.
This intermixing of the two equations occasionally
results in negative values. for R. It is suggested
that (1) biological sample collection and analysis be
standardized prior to use or comparison of diversity
index and its associated parameters among various
aquatic systems and (2) if necessary, a more appro-
priate term be selected for redundancy, an expres-
sion in which Brillouin and Shannon equations are
not arbitrarily intermixed.

R:

Invertebrate drift in Alaskan streams

Drifting benthic invertebrates were collected at
nine stream sites along the trans-Alaska pipeline
route during 1972 by J. W. Naum-an and D. R.
Kernodle (1974) . The samples were taken with drift
netshexposed for 1-h periods during daylight on
three occasions designated as typical of spring, sum-
mer, and fall. Collectively, the dominant groups were

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES 191

water fleas (class—Crustacea), midges (family—
Chironomidae), blackflies (family—Simuliidae),
and mayflies (order—Ephemeroptera). 0A total of
14,249 organismswere enumerated, and 86 taxa
were identified fro-m the 27 samples. Water fleas
were dominant in. an Alaskan North Slope stream,
whereas midges Were the most common invertebrate
in a maritime stream near Valdez. From pooled
samples for all three seasons at each site, brown-
water streams had more species, whereas clear-water
streams had greater species diversities. The midges
were the most diverse, with 25 different taxa identi-
fied. Midges tended to be more diverse in Arctic Slope
streams as compared to the other stream sites
samples. Drift biomass was variable both seasonally
and for different stream sites. However, bio-mass
tended to increase during spring and fall, ranging
from 0.06 to 3.0 g/h.

Comparison of sampling methods for benthic invertebrates

During a study of the Dietrich River, a mountain
stream of arctic Alaska, K. V. Slack, J. W. Nauman,
and L. J. Tilley compared the results obtained using
the following techniques for collecting benthic in-
vertebrates: (1) A 1-h drift-net collection was ob-
tained at. five upstream stations that had not been
disturbed by other sampling. The net, held perpen-
dicular to the flow, had an opening of 30x30 cm and
0.471-tm mesh. (2) A dip net with 0.210-um mesh
was used to sample the major aquatic habitats at the
five stations. Sampling effort in each habitat was
about in proportion to its occurrence at each station.
(3) Ten streambed rocks were lifted at random from
the major habitats, scrubbed with a brush in a
bucket of water, and the combined sample was con—
centrated on a sieve with O.210-,um mesh.

Most groups of organisms were more abundant
and diverse in the dip-net samples. A few groups,
notably certain shore-living insects (Collembola)
and aquatic mites, were most abundant and diverse
in the drift-net samples. Although the 10-rock
samples were similar in composition to many of the
samples taken with the dip net, the lO-rock samples
were apparently too small to include some of the less
abundant taxa. Collection of some midge (Chirono-
midae) larvae was more effective with the 10-rock
method than with either of the other methods. The
manner of scrubbing the rocks for the 10-rock
sample may have resulted in more complete re-
moval of ‘small or burrowing larvae from rocks or
masses of algae and moss. Because of the prepon-
derance of Chironomidae in the Dietrich River
benthos, the 10-ro-ck method proved to be about as

effective as the dip-net method in collecting benthic
invertebrate individuals but only about half as effec-
tive in collecting the different taxa. More taxa were
collected by the drift-net method than by the 10-rock
method, and as many individuals were collected by
the drift-net method as by the 10-rock method. More-
over, the drift-net samples contained many pupae,
adult insects, and terrestrial invertebrates which did
not occur in the other samples. The following conclu-
sions resulted from the study: (1) The number of
taxa collected from a station was increased when
more than one method of sampling was used; (2)
dip'net effectiveness probably could be enhanced by
more thorough scrubbing of rock surfaces to dis-
lodge clinging or burrowing organisms; and (3) the
value of a simple drift net as a passive collection
method was shown. Finer mesh-size netting with an
adequate percentage of open area should increase the
effectiveness of drift sampling by retaining the
smaller individuals.

Evaluation of artificial substrates for benthic invertebrates
Four types of artificial substrates—Bar-b—que
basket, Bull basket, Flexiring, and Hester-Dendy
multiple plate—were placed in the Eel River and
Elder Creek near Branscomb, Calif. R. F. Ferreira
studied the effects of artificial substrate type, sam-
pling period (late spring to late summer), stream
(river or creek), and habitat (pool or riffle) on
benthic invertebrate colonization of artificial sub-
strates. There was a significantly higher number of
organisms and of different taxa on each of the four
types of artificial substrates placed in riffies than
were found in pools. However, diversity-index values
did not show a significant difference in benthic in-
vertebrates colonized between riffles and pools.
Stream and sampling period had no effect on coloni-
zation of the artificial substrates. The main factor
‘affecting colonization by benthic invertebrates was
the artificial substrate type. A significantly higher
number of organisms and number of taxa occurred
on the Bull and Bar-b-que basket substrates than on
the Flexiring and Hester-Dendy multiple-plate sub-
strates. The difference was also shown by a signifi-
cantly higher diversity index calculated for the Bar-
b—que and Bull basket samples. However, the Bar-b-
que basket substrate had advantages over the Bull
basket; the Bar-b-q'ue basket is easier to construct,
can be placed on the stream bottom in any position,
and does not fill with silt as quickly as the Bull
basket.

 

192

PLANT ECOLOGY

Computer model predicts forest changes

A computer model is being developed by R. L.
Phipps to simulate population dynamics of mixed
stands of southern wetlands forests. The model,
which is basically a tree-growth model utilizing aver-
age or typical growth characteristics of trees on site,
is intended to be used as a tool for predicting vege-
tation change as a function of hydrologic change. It
is being tested by Phipps, using data from the White
River National Wildlife Refuge in southeastern
Arkansas. A tentative conclusion is that relatively
great changes in flood frequency and duration result-
ing from manmade flood-control measures may
change the composition of tree species in undisturbed
forests very little. However, any disturbance to the
forest canopy, such as lumbering or managed en-
hancement of wildlife mast production, could be ex-
pected to result in pronounced changes in species
composition.

Saltcedar establishment related to seed production and reservoir
water levels

Field studies of three aspects of saltcedar (Tam-
arix chinensis) ecology were conducted in southeast-
ern Arizona by R. M. Turner (D. K. Warren and
R. M. Turner, 1975). Seed production, seedling
establishment, and seed mortality from submergence
were examined because of the important bearing
each has on the spread of this species in the South-
west. Seed production in a dense stand of saltcedar
yielded 17 seeds/cm2 during the seed-producing sea-
sons. During the 5.5-mo period of seed production
there was one major production peak and one minor
production peak. Seed production of two native ri-
parian species, seepwillow (Baccharis glutinosa)
and cottonwood (Populus fremontiz‘), was studied
and compared with saltcedar seed production.

The rate of establishment of saltcedar seedlings
on the banks of a reservoir with receding water
levels corresponded closely to the rate of seed pro-
duction of nearby plants. The period of greatest
establishment occurred between early May and mid-
June; 47 seedlings were found in one 6-cm2 area.

Mature saltcedar plants were able to survive com-
plete sub-mergence for as long as 70 (1. Plants that
were not completely submerged survived longer
periods of flooding—the maximum was 98 (1.

Natural reforestation less on coal strip mines than on abandoned
farmland

T. M. Yanosky and R. S. Sigafoos compared natu-
ral reforestation of coal strip-mine spoils in south-

 

GEOLOGICAL SURVEY RESEARCH 1975

eastern Kentucky to that on nearby abandoned farm
fields. They estimated that abandoned-farmland
plots yield about four times as many trees per acre
as do mine-spoils plots. On the farmland, crown
density of pine trees is nearly twice that on the
spoils and the total cross-sectional area of tree
trunks is seven times greater. The lesser quantity
of vegetation on the spoils is probably related to
poorer site conditions; there are greater distances
between trees on mine spoils than between the same
species of trees on farmland.

NEW HYDROLOGIC INSTRUMENTS AND
TECHNIQUES

G. F. Smoot and H. 0. Wires reported that 12 op-
erational models of a streamside, multiparameter,
automatic water-quality monitor are giving excellent
service and additional units will soon be in use.

Wires reported that an automatic orifice-purge
capability added to field stage-recording manom-
eters has increased the accuracy of records at
alluvial streamflow _sites.

According to Wires, digital data-collection sys-
tems installed at big-dam field sites have been modi-
fied to improve reliability and system flexibility.

Wires also reported that specifications have been
drafted and a bid has been accepted for additional
satellite hydrologic data-collection platforms to be
used with LANDSAT or with GOES.

Three automatic storm-water data-collection sys-
tems have been installed in northern Broward
County, Fla. The data-collection systems were de-
veloped by USGS personnel to simultaneously record
rainfall and storm-sewer flow and to collect multi-
ple water—quality samples throughout a storm event.
According to C. B. Sherwood, Jr., and Jack Hardee,
sample collection will continue for 2 yr at each of
the three sites. Sites selected for study are a single—
family residential area, a segment of six-lane di-
vided highway, and a major shopping center.

A. M. Sturrock, Jr., and H. E. Jobson reported
that radiation data were recorded continuously at
two southern California field sites about 26 km
apart. Solar radiation was sensed at both sites by
Eppley precision spectral (shortwave) pyranom-
eters. Atmospheric radiation was sensed at one
site by an Eppley (longwave) pyrgeometer and the
total (all-wave) radiation was sensed at the other
site by a Beckman-Whitley flat-plate radiometer.
The atmospheric radiation at the flat-plate radiom-
eter site was determined to be the difference be-

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

tween the instantaneous all-wave and the instantan-
eous shortwave components. On a daily average
basis, both instruments gave results which appeared
to be of comparable accuracy, and the measured
values of the longwave component agreed reasonably
well with values computed from formulas. On an
instantaneous basis, the Eppley pyrgeometer gave
results‘which agreed fairly well with the computed
longwave values. The ratio of the mean maximum
output to the mean minimum (nighttime) output
was stable in the range of 1.3 to 1.4. The measured
flat-plate radiometer values, on the other hand, ap-
peared to be too low at night and too high during
the day. The ratio of the mean maximum output to
the mean minimum output was 3.5 for the 35 days
analyzed. This ratio decreased somewhat with in-
creasing cloudiness.

W. S. Keys is making logs of holes deeper than
1,372 m, using a logging truck which has a large
hoist unit with 4,877 m of high-temperature 7-con-
ductor cable. Keys reported that the following field—
proven high-temperature probes are now being util-
ized in geothermal studies: (1) Temperature, (2)
natural gamma, (3) gamma-gamma, (4) neutron,
(5) caliper, and (6) normal resistivity.

Keys also reported that acoustic televie-wer logs
were used to interpret the results of a hydraulic
fracturing test in a geothermal well in New Mexico
and to identify sources of hot water in test holes in
Idaho.

I. L. Burmeister reported that the Mississippi
River at Clinton and Keokuk, Iowa, is being sampled
with the use of a special boom mounted on a garden
tractor. The standard USGS base-and-boom rig
could not be used at the Keokuk site because of a
confined 81-cm-wide sidewalk. The special rig, de-
signed by Burmeister, consists of a davit-type boom
with a type E—53 power reel mounted on a model
VH70, 7-hp-John Deere garden tractor. The maxi-
mum width of the tractor is 69 cm. The alternator
on the tractor provides sufficient charge to the 12—V
battery of the tractor to operate the power reel and
safey light. An extra Hot Shot battery is required
to operate the 45-V solenoid of the P-61 sampler.
A case of sediment bottles is strapped on the hood.
The rig is towed on a small, low-bed trailer to a
site; the operator then drives it onto a bridge and
takes samples. It is also used on bridges without
sidewalks. Its 8-km/h speed and its flashing safety
light make it easier, faster, and safer to use than a
standard base-and-boom rig. Also, the rig has been
used to make complete discharge measurements.

 

193

J. V. Skinner and J. P. Beverage tested some new-
ly developed commercial instruments for sampling
and for analyzing sediment. In one flume study a
small pumping sampler was used to extract samples
from the flow. Samples were then compared with
siphoned samples extracted through the same intake
tube. The intake tube passed through the flume wall
and extended 5 cm into the flow. Angled down-
stream to shed debris, the intake extracted samples
at nearly right angles to the flume flow. Under ad—
verse conditions (3-m vertical lift, battery-power
mode) the pump maintained velocities of approxi-
mately 60 cm/s in the 0.6-m intake line. This velocity
proved to be adequate for transferring particles
from the mouth of the intake to the discharge side
of the pump. The sediment concentration in the test
suspension consisted of Missouri River sand; 95 per-
cent of the material was finer than 400 pm and 5
percent was finer than 62 ,im with D50 of 180 Mm.
Compared to samples extracted isOkinetically, both
pumped and siphoned samples were lower in sedi-
ment concentration, but this deficiency was a char-
acteristic of the intake and not of the pumping sam-
pler itself. To reduce cross contamination of sam-
ples, the sampler was designed to backflush with
air, but the tests revealed that in long horizontal
runs, traces of sediment did remain in the intake
line. More serious errors were caused by deposition
within the sampler’s distributor system, which
routes samples from the pump to sample containers.
However, the sampler proved to be very reliable,
and its small size and battery-powered feature make
it attractive for use at sites where the bulk of ma-
terial in suspension is silt and clay.

A laboratory-based particle sizer was evaluated
for routine laboratory analysis. A sample was il-
luminated by a rotating laser beam which detected
light scattered by suspended particles, and the pulses
were used to count and size individual particles.
Concentrations as low as a few parts per billion
were detected, but drift was too large to permit
size-distribution measurements.

In cooperation with J. M. Killen (Univ. of Min-
nesota), Beverage and Skinner tested a modification
of the falling-drop technique. In this technique, a
single drop of test suspension is placed in an im-
miscible liquid; the fall velocity of the drop is
measured and, by calibration, the sediment concen-
tration within the drop is determined. Anisole was
used for the immiscible liquid in the original devel-
opment work performed by J. M. Pezzetta (Univ.
of Wisconsin). Because anisole is quite toxic, a
special instrument oil was substituted for anisole in

194

the modified technique. With very precise tempera-
ture control, the lower limit of detection was found
to be about 200 mg/l. _

Beverage and Skinner constructed a special hy-
drometer for rapid measurement of concentration.
With temperature controlled to within i0.5°C, the
lower limit of detection was about 50 mg/l.

USGS investigators, in cooperation with R. H.
Rust (Univ. of Minnesota), are evaluating a com-
mercial optical size analyzer. Particles are first de-
posited on a membrane filter which, through chemi-
cal treatment, is rendered transparent. By means
of an electronic scanner and microscope, particles
are automatically counted and classified by size. Re-
sults are encouraging, but the relationship between
particle weight and registered particle size requires
additional study.

Beverage and Skinner made a preliminary evalua-
tion of errors in sampling through nappes at the
free outfall of a narrow channel. To date, the range
of conditions studied has been limited to outfall
flows 30 cm wide and 10 cm deep. A DH—48 sampler
was used to collect depth-integrated samples a few
millimetres downstream from the lip. The sampler’s
air exhaust was completely ventilated in the shal-
low flow, and this effect, combined with adverse ap-
proach conditions, reduced the sampler’s intake ve-
locity by about 10 percent. The material in transport
was Missouri River sand in suspension. For each run
the sampling error was based on the difference be-
tween sediment discharge computed from sample
concentrations and sediment feed rate measured at
a vibrating feeder that injected sediment into the
flow 8.8 m upstream from the outfall. The mean
sampling error was 0.5 percent with a standard
deviation of 13 percent. Additional tests would prob-
ably reveal a larger mean error, but the existing
data do not suggest a serious systematic sampling
bias. Results of these tests are applicable to field
sampling at culvert outfalls. Results show that a
number of closely spaced verticals must be sampled
even if the nappe width is narrow. Because of the
30-cm outfall-flow width, a minimum of three ver-
tical samplings was necessary to adequately ac-
count for the large concentration gradients in the
lateral direction. Also, in the laboratory as in the
field, collection of precise discharge-weighted sam-
ples is difficult. The problem stems largely from
shallow depth and high velocity. For most accurate
results, the sample from each vertical should be
analyzed separately. This permits an assessment of
the magnitude of the gradients, and then, if neces-
sary, the concentrations can be discharge weighted

 

GEOLOGICAL SURVEY RESEARCH 1975

in the computational phase. Unfortunately, this com-
putation requires a knowledge of velocity distribu-
tion with the nappe. The investigators hope to ex-
tend the study to a wider range of conditions, and,
by making additional runs within each group,
strengthen the statistical significance of the con-
clusions.

COMPUTER PROGRAMS FOR MODELING AND
SOLVING HYDROLOGIC PROBLEMS

R. S. Chicko developed a computer program that
solves for porosity and lithology, given digitized
acoustic velocity, density, and neutron porosity
logs. The computer program formulates the lithology
problem as a linear-programming model and then
solves this model by the simplex method. The com-
puter program has many advantages over previous-
ly attempted approaches, such as cross-plot tech-
niques and the solution of simultaneous linear equa-
tions. The linear-programming formulation does not
permit negative solutions and, thus, ends a long-
standing problem. Also, the computer program is
able to solve more unknowns than previous numeri-
cal techniques. Because the computer program in-
corporates statistical analyses of core data, the com-
puted solutions are forced to conform with actual
lithology.

Chicko and T. A. Taylor developed a system to
generate a multiplexed data base for condensed stor-
age and rapid access to digitized borehole geophysi-
cal logs. Logs made with the research equipment
are digitized in the field on magnetic or punched
tape. Existing analog records may be digitized com-
mercially. Digitized data are input, stored, processed,
and summarized for a reference library and rapid

‘ computer interpretation.

SEA-ICE STUDIES

Many advances have been made in using remote-
sensing techniques to study the morphology and dy-
namics of sea ice, and the resulting data are being
applied to numerical models of pack ice. Remote-
sensing techniques have been used in recent sea-ice
experiments, and results have been highly successful.

Remote-sensing studies of sea ice

Results derived by W. J. Campbell (D. C. Meeks,
R. O. Ramseier, and W. J. Campbell, 1974) from a
comparative study of. 13.4-GHz passive-microwave
surface measurements of physical, chemical, and
structural properties of Arctic sea ice illustrate dis-
tinct decreasing microwave emissions for first-year,

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

transitional, and multiyear sea-ice types. There is a
structural relationship for microwave emissions by
transitional and multiyear sea ice. Both vertically
and horizontally polarized measured brightness tem-
peratures decrease linearly with increasing average
ice porosity. In first-year ice, however, measured
brightness temperatures are comparatively uniform
and microwave emission appears to be more strongly
influenced by high near-surface salinity combined
with the occurrences of uniform porosity. Another
study (R. O. Ramseier, W. -J. Campbell, W. F.
Weeks, L. D. Ars-enault, and K. L. Wilson, 1975) in-
volved the use of LANDSAT— imagery acquired over
a 1-yr period to study in detail the ice dynamics and
morphology of parts of the Arctic Ocean and‘the
Canadian Archipelago. The use of remote-sensor
imagery to describe one complete cycle of ice freeze-
thaw processes and drift patterns saved an enormous
amount of time, expense, and manpower.

Joint U.S.-U.S.S.R. Bering Sea Experiment

The joint U.S.-USSR. Bering Sea Experiment
(BESEX) took place in February and March 1973
and involved both Soviet and American aircraft, the
U.S. Coast Guard icebreaker, Staten Island, and the
Soviet weather ship, Priboi, in a detailed remote-
sensing study of the Bering Sea. A NASA aircraft,
the Galileo, was equipped with cameras and passive-
microwave and infrared radiometers for imaging
the morphology and distribution of sea ice in the
Bering Sea. According to W. J. Campbell (W. J.
Campbell, Per Gloersen, and R. 0. Ramseier, 1974;
Per Gloersen, R. O. Ramseier, W. J. Campbell,
P. M. Kuhn, and W. J. Webster, J r., 1974 ; R. 0. Ram-
seier, Per Gloersen, W. J. Campbell, and T. C.
Chang, 1974; Per Gloersen, R. 0. Ramseier, W. J.
Campbell, T. C. Chang, and T. T...Wilheit, 1974) , the
following five distinct ice types Were discernible;
(1) Gray ice, 20 cm thick; (2) gray-white ice, 40
cm thick; (3) white ice, 60 cm thick; (4) white and
first-year ice, 100 cm thick; and (5) transition-zone
ice (frazil, grease, and small pancake ice). Most of
the pack ice is formed in the Bering Strait. The
pack ice is entirely first-year and younger, and dur-
ing the experiment its concentration ranged from 74
to 90 percent within a roughly constant geographic
area of approximately 10,000 kmz. Anticyclonic ac-
tivity in the area advected the ice southward with
strong divergence and a regular lead and polynya
pattern; cyclonic activity advected the ice northward
with ice convergence, or slight divergence, and a
random lead and polynya pattern.

 

195

Skylab—4 photographs used for floating-ice studies

In addition to data which were collected by the in-
struments comprising the Skylab Earth Resources
Experimental Package (EREP) , the Skylab—4 astro-
nauts obtained photographs, taken by hand-held
cameras, of target areas designated for floating-ice
studies. The main objective of the study was to gath-
er information on sea ice in the Gulf of St.- Lawrence
and lake ice in Lake Ontario. The Skylab—4 crew
obtained photographs of sea ice in the Bering Sea,
the Sea of Okhotsk, and James Bay and of large
tabular icebergs in the South Atlantic. W. J. Camp-
bell (W. J. Campbell, R. O. Ramseier, W. F. Weeks,
and J. A. Wayenberg, 1974) reported that the se-
quential photographs provided very useful informa-
tion on distribution of ice and ice types, overall de-
formation patterns, and amount of ice movement be-
tween flows.

ANALYTICAL CHEMISTRY

Spectrofluorometric determination of thalliumin silicate rocks

A sensitive spectrofluorometric procedure to deter-
mine submicrogram and microgram quantities of
thallium in silicate rocks was developed by M. M.
Schnepfe (unpub. data, 1975). Samples are decom-
posed with a mixture of hydrofluoric and nitric acids
and then treated with hydrochloric acid. Thallium is
extracted as the dithizonate from an alkaline medium
containing ascorbate, citrate, and cyanide salts by
using chloroform and is then back-extracted with
dilute nitric acid. The organic matter is destroyed,
and the sample is treated with bromine, hydrochloric
acid, aluminum chloride, and rhodamine B. The rho-
damine B chlorothallate is extracted with benzene,
and its fluorescence is compared with standards.
With this procedure, 10 ng T1 in pure solution can
be determined with a relative standard deviation of
5 percent; the determination limit is thus set at ap-
proximately 10 ng for a 1-g sample. The thallium
content of USGS standard rocks G—1 and W—1, ac-
cording to duplicate determination with this pro-
cedure, is 1.09:0.01 ,rg/g T1.

Determination of trace amounts of bismuth

W. H. Ficklin and F. N. Ward used an atomic ab-
sorption spectrophotometer equipped with a graphite
furnace to determine trace amounts of bismuth down
to 10 ng in soils and rocks. This analytical technique
can be used to differentiate crustal abundance levels
of bismuth from enrichment levels to outline targets
of mineral deposits of possible economic importance.

196

Enhanced sensitivity of a spectrophotometric germanium

determination

L. P. Greenland, in continuing studies of the ger-
manohe-teropoly acid complex of molybdate, de-
veloped the most sensitive known color reaction of
germanium. A tributyl phosphate-cyclohexane ex-
traction of the yellow heteropoly acid yields a molar
absorptivity of 21,000 at 310 nm in comparison with
values of 2,400 and 9,100 cited by Sandell for the yel-
low and the blue heteropoly acids, respectively, and
a value of 14,500 for the germanium phenylfluorone
complex. Interferences are removed prior to the de-
termination by extracting the GeCl4 with 0014 or
with 02014 with equal efl‘iciency. The latter extraction
technique has the advantages of lower volatility and
toxicity. A working range of 0.1 to 1 pg Ge is ob—
tained in a 5-ml volume by using a 5-cm light path.

Rock analysis procedures revised

In a revised USGS Bulletin, Leonard Shapiro
(1975) described rapid methods of analysis for 16
major constituents. Spectrophotometric methods are
used for Si02, A1203, Fe203, Ti02, P205, and MnO,
whereas CaO, MgO, Na20, and K20 are determined
by using atomic absorption spectrometry; H20+,
H201 FeO, C02, F, and S are determined by other
techniques.

ISOTOPE DILUTION

Rapid determination of lead in rocks

P. J. Aruscavage developed a substoichiometric
isotope dilution method for the rapid determination
of lead in rocks. After acid decomposition of samples
containing 1 to 5 ,lg Pb in the presence of Pb“ tracer,
lead is extracted with dithizone and reacted with a
substoichiometric amount of ethylenediamine tetra-
acetic acid. Lead content is calculated from the spe-
cific activity of the complex after removal of excess
lead with dithizone. Results obtained with standard
rocks show excellent precision and accuracy in com-
parison with isotope dilution-mass spectrometry.

Determination of nanogram amounts of silver

A rapid procedure for the routine determination
of nanogram amounts of silver in rocks was described
by E. G. Lillie (1975). After dissolution of the sam-
ple with a hydrofluoric-nitric-perchloric acid mixture
in the presence of Ag110 tracer, the silver is separated
by (1) extraction as the dithizonate into xylene and
(2) back-extraction into dilute hydrochloric acid.
After evaporation and removal of the hydrochloric
acid, the silver is taken up in an acetic acid-sodium

 

GEOLOGICAL SURVEY RESEARCH 1975

tartrate buffer solution and reacted with a constant
amount of radioactively labeled iodide. The silver
iodide formed is isolated by extraction into amyl
alcohol, and silver is determined by the ratio of the
counting rate of the iodide to the counting rate of the
silver in the silver-iodide complex. The method can
determine as little as 0.005 ,Lg/ g Ag in 0.5-g sample.

ACTIVATION ANALYSIS

A semiautomated processing technique for analysis

A computerized semiautomated system for proc-
essing samples by instrumental neutron activation
analysis was completed when P. A. Baedecker wrote
the computer program to generate a printed sum—
mary of analytical results. This program, now‘in use,
produces a printed report that lists concentration
and sigma based on counting statistics for Fe, Ba,
Co, Cr, Ca, Hf, Rb, Sb, Ta, Th, Zn, Zr, Sc, La, Ce, Nd,
Sm, Eu, Tb, Yb, and Lu. This procedure eliminates
the need for typing a report. Sample changes permit
the multichannel analyzers to automatically collect
gamma-ray spectra onto magnetic tape, after which
the gamma-ray data are computer-processed to de-
termine the concentrations. When more than one
gamma-ray peak is used for the calculations, the pro-
gram provides a weighted average for the concentra-
tion to be reported. Concentration data are transfer-
red to a disk for collation with additional counting
data for the samples. Data are finally taken from the
disk and processed to provide the final report of the
analysis.

Radiochemical determination of low concentrations of nickel in

rocks and minerals

R. A. Zielinski (unpub. data, 1975) developed a
radiochemical procedure for the determination of
very low concentrations of nickel in rocks and min-
erals. Accuracy and precision are estimated to be
:5 percent to levels as low as 0.1 ,ug Ni. Sensitivity
is 0.1 pg Ni. These values represent a marked im-
provement over possible competing analytical tech-
niques. Samples are irradiated, combined with a
nickel carrier, and treated by a series of purification
procedures including collection of nickel in a lead
bead by means of a fire assay technique; refusion of
the lead bead and precipitation of basic element hy-
droxides; washing and dissolution of precipitate;
and anion exchange chromatography and precipita-
tion of nickel dimethylglyoxime. The precipitate is
weighed to determine chemical yield and counted for
beta activity along with a precipitate from an irradi-
ated nickel standard solution.

GEOLOGIC AND HYDROLOGIC PRINCIPLES, PROCESSES, AND TECHNIQUES

Fission-track technique for the measurement of uranium in

[solutions

A fission-track procedure for the determination of
uranium concentrations in aqueous solutions was
tested by R. A. Zielinski. A standard and a sample
solution (1.0 ml) and submerged squares of low-
uranium fused-quartz glass are heat sealed in lengths
of polyethylene tubing and irradiated for up to 4 h
at a neutron flux of 2.5><1012 n/crnz/s. The glass
platelet-s are recovered and etched for 1 min in 48
percent HF to develop fission tracks. Track densities
produced by the samples and the standard are deter-
mined by microscope observation and compared.
Track densities are linearly proportional to uranium
concentrations over the investigated range of 100
ng/ g to 100 ,g/ g. Uranium concentrations as low as
10,11/ g can be measured by this technique. Corrections
must be applied for solutions with Um/U235 ratios
differing from the natural ratio.

EMISSION SPECTROSCOPY

Improved accuracy in computerized emission spectrographic

analysis of geologic materials

The transport and excitation of atomic vapors in
the d-c arc plasma determine the time-integrated
spectral line intensities that are measured by com-
puterized emission spectrography. These processes
must be similar for samples and standards to assure
accurate analyses for elements in the samples. D.W.
Golightly, C. P. Thomas, A. F. Dorrzapf, Jr., and
C. S. Annell (1975) investigated these processes for
more than 60 constituent elements in diabase, gran-
ite, andesite, peridotite, and shales by means of auto-
mated microphotometry and computerized data proc-
essing. Intensities, integrated over the arcing time,
for major constituent elements are found to be
similar.

A calculator program for quantitative spectrographic analysis

A. L. Sutton, J r., wrote a program for either the
Wang 520 or the Wang 600 calculator to make all the
calculations required for quantitative spectrographic
analysis. This program has subroutines for both the
Crosswhite—Deike and the ASTM 2-step emulsion
calibration methods, a second-degree fit for analytical
curves, and subroutines to evaluate the polynomials
and calculate the final analytical results for samples.
Provisions are also made for dilution factor and back-
ground corrections. The minimum machine require-
ments are 1,848 program steps, a printer, and a
tape cassette unit. The program is available in the

 

197

form of magnetic tapes and instructions directly
from Sutton.

High-resolution gamma-ray spectrometer for uranium-series
isotope studies

A recently developed high-resolution gamma-ray
spectrometer permits identifications, in the labora-
tory and in the field, of several uranium-series iso-
topes that are not resolved by conventional detectors.
The planar intrinsic germanium detector, developed
by R. M. Moxham, permits detailed examination of
the 10- to 200-keV gamma- and X-ray region, where
many closely spaced spectral lines from the uranium-
series nuclides are found. In-thigh—grade ore, these
include 238U, 235U’ 234Th, 231Th’ 230Th, zzeRa’ 223Ra’
214Pb, and 21°Pb.

The preliminary studies in the laboratory indicate
that uranium can be determined quantitatively inde-
pendent of the state of secular'equilibrium and that
the state of equilibrium can be measured for some
members of the series. The amplitudes of these peaks
in low—grade material have yet to be determined.

Borehole logging with a neutron activation probe

A nuclear marine probe was constructed by using
a 252Cf neutron source and a Ge(Li) detector cooled
by a prefrozen propane canister technique developed
in the physics laboratory in Reston, Va. The probe
was used to test the feasibility of making in-place
captive gamma-ray spectrometry measurements in
bottom sediments in a marine environment. Chlorine
causes serious interferences in the spectra and an
energy hardening of the average neutron flux dens-
ity, so that pure thermal neutron capture is not
attained in practice.

ANALYSIS OF WATER

Aluminum species in solution

Aluminum hydroxide particles small enough to
pass a 0.1-pm-diameter-pore filter may occur in
natural water. Dissolved-aluminum concentration
values used in thermodynamic calculations should
not include these aluminum species. R. B. Barnes
( 1975) found that only the ionic forms of aluminum
are determined if a complexing agent (oxine) is
added to the sample at the time of collection, and
the sample is immediately extracted with methyl-
isobutyl ketone.

Selenium

An atomic-absorption spectrophotometric method
for determining selenium in water was developed

198

by Myra Lansford, E. M. McPherson, and M. J.
Fishman (1974'). The method involves evolution of
hydrogen selenide by reduction of selenite with
stannous chloride in 6-M hydrochloric acid solution.
The hydrogen selenide is subsequently swept from
the sample solution by a stream of nitrogen into a
hydrogen flame and its absorption is measured at
196 nm. Arsenic interference can be avoided by care-
ful control of the amount of stannou's chloride added.
Mercury interference occurs when its concentration
exceeds 25 pg/l. As little as 1 ,g/l of selenium can
be measured. Incorporation of preliminary digestion
of a sample ensures decomposition of organic sele-
nium compounds.

Nitrogen compounds

The use of a Technicon aluminum-block digestor
to decompose organic nitrogen compounds in water
samples was evaluated by D. E. Erdmann and found
to be satisfactory for determining ammonia plus
organic nitrogen. Forty samples are digested simul—
taneously during a 2.5-h heating period on an elec-
tric hotplate; only 20 ml of sample is required. The
digested sample is cooled and adjusted to pro-per vol-
ume, and the resultant ammonium salts are deter-
mined by an automated procedure involving the col-
orimetric reaction of ammonium ion with sodium
salicylate, sodium nitroprusside, and sodium hypo-

 

GEOLOGICAL SURVEY RESEARCH 1975

chlorite in an alkaline solution. As little as 0.1 mg/l
of ammonia plus organic nitrogen can be determined
by this procedure.

Ferricyanide and thiamine

M. C. Goldberg and J. K. Wilson found that ferri-
cyanide or thiamine in water can be determined by
measuring the fluorescence of the complex formed
between these two compounds. Several substances,
including cyanides, interfere. Cyanide interference
can be prevented by complexing with silver ion.

Neutron activation analysis

The carrier-sulfide radiochemical separation used
in the neutron-activation analysis of water some-
times gives erratic results for arsenic, antimony,
and zinc. L. L. Thatcher modified the procedure by
using thioacetamide and introducing new elements
into the carrier; as a result, recovery of arsenic,
antimony, zinc, and 14 other elements improved,
and there was less sodium contamination. The tech-
nique was used to analyze snow samples from Den-
ver, Colo.; aluminum, copper, and manganese were
found, possibly correlating with certain aspects of
urban pollution. The technique was also applied to
investigations of interactions between dissolved
metallic ions and sediment particles.

GEOLOGY AND HYDRQLOGY APPLIED TO THE PUBLIC WELFARE

EARTHQUAKE STUDIES

GEOPHYSICAL STU DIES

Seismicity

The USGS program of earthquake monitoring in
the seismically active southern California region con—
tinued to expand in 1974 with the installation of a
27-e1ement seismograph network in the Mojave
Desert. D. P. Hill and G. S. Fuis reported that results
thus far support earlier indications that most of the
seismic activity occurs in the western half of the
Mojave Desert (west of long 115°30’ W.). A swarm
of local earthquakes, several of them larger than
magnitude 4, occurred in August 1974 near the Pis—
gall fault just outside the northern margin of the
Mojave net. Composite first—motion plots indicate
right-lateral strike-slip motion on a plane parallel to
the northwest-trending Pisgah fault.

The southern Alaska seismic net continued to ex-
pand its coverage, and, with the installation of 19
new telemetered stations in the Yakataga seismic
gap by E. E. Criley, M. E. Blackford, R. A. Page, and
G. E. Loo, the total number has now been increased
to 51. This region, between Prince William Sound and
Yakutat Bay, has not experienced any great earth-
quakes since the 1899 and 1900 magnitude 8+ earth-
quakes, and, during the past 15 yr, only a small num-
ber of earthquakes have been located in this region
by distant worldwide seismic stations. Microseismic
activity recorded there since network installation in
September 1974 has been low relative to that re-
corded in the Prince William Sound and Cook Inlet
regions. Two biaxial borehole tiltmeters were in-
stalled by C. E. Mortensen, M. J. S. Johnston, and
Page on Middleton Island, at the western margin of
the seismic gap. Preliminary data indicate active
tilting of the island.

J. C. Lahr and Page used the local net supple-
mented by teleseismic data to delineate the extent
and configuration of the Beniofl" zone beneath south-
ern Alaska. The upper part of the zone has a low dip
and extends up to 400 km northwest of the Aleutian

 

trench, then steepens and descends to a depth of 150
to 200 km, and reaches as far north as the northern
foothills of the Alaska range.

J. D. Unger and P. L. Ward made a careful study
of the seismic P-wave travel-time residuals from the
April 26, 1973, magnitude 6.2 earthquake off the
northwestern coast of Hawaii in order to infer upper
mantle structure beneath the Hawaiian Islands. The
30 USGS stations on Hawaii permit precise location
of the quake and the determination 'of its origin
time. These measurements, in turn, allow a determi-
nation of very accurate absolute travel times to more
distant stations. Differences between observed and

expected travel times give clues to the structure be-

neath Hawaii, and it appears that P—wave velocities
are abnormally low in the upper mantle beneath the
island of Hawaii or to the southwest of it.

w. H. Bakun and c. G. Bufe reported that body-
wave spectra from central California earthquakes
recorded at local stations have shown large spatial
variations in attenuation and propagation path char-
acteristics. Shear-wave attenuation cOefficients differ
by at least a factor of 3 betweenpropagation paths

\in the San Andreas fault zone and those in the Gabi-

lan Range to the west of the fault.

A. C. Tarr and K. W. King used data from a new
10-station seismographic net installed in South Caro—
lina in 1974 to survey the seismicity and help assess
the earthquake hazard in that State. Preliminary
results from a local five-station network in the
Charleston-Summerville region indicate microearth-
quake activity in the area of the destructive 1886
Charleston earthquake. Elsewhere, seismicity is scat-

~ tered in small local clusters, and, at present, the-re is

no evidence for a northwest-trending zone from
Charleston to the Appalachians, as has been postu-
lated by several previous investigators.

S. W. Stewart and L. B. Nichols developed a time-
shared interactive graphics computer system to
speed up the daily analysis of earthquake waveforms.
The system uses a low-cost storageetube-type com-
puter graphics terminal connected by telephone line
to a large-scale computer. Earthquake waveforms are

199

200

read into the computer from magnetic tapes. By
typing in simple commands at the keyboard, the sci-1
entist may display and manipulate two or more
earthquake waveforms at a time. A key feature of
the system is that it allows the scientist to interact
and guide the processing of each earthquake wave-
form through the computer.

Earthquake prediction

The USGS central California seismic. net, now
comprising 132 stations, was used increasingly in
1974 as a research tool in earthquake prediction ex—
periments designed to detect possible seismic-wave
velocity changes prior to moderate local earthquakes.
R. L. Wesson, Russell Robinson, C. G. Bufe, W. L.
Ellsworth, J. H. Pfluke, and J. A. Steppe reported
changes in P-Wave velocity measured by observing
travel paths from local earthquakes through the
zones of two imminent earthquakes, one of magni-
tude 4.6 and the other of magnitude 5.0. In addition,
for three other events between magnitudes 4 and 5,
anomalously deep microearthquake activity was ob-
served prior to the shocks.

J. H. Healy and colleagues have been carrying out
an intensive experiment in the Bear Valley, Calif,
region to determine crustal structure of the San
Andreas fault zone and to search for seismic velocity
changes preceding earthquakes. The experiment sup-
plements the central California network stations with
a very dense portable array of up to 100 stations,
which are telemetered by radio or by hard wire back
to a single tape recorder. Results obtained thus far
indicate that velocity changes, if they exist, are
either small or at considerable depth in the fault
zone. The portable system that has been developed
for this experiment will also be useful in other de-
tailed seismological investigations, such as the ex-
ploration of geothermal areas.

Bufe, Pfluke, and Wesson found that the mean
apparent focal depths of microearthquakes occurring
along a 20-km stretch of the San Andreas fault
southeast of Hollister, Calif, increased by 25 per—
cent some 60 days before the magnitude 4.6 Stone
Canyon earthquake of September 4, 1972. The shape
of the time-depth anomaly is virtually identical to
the time plots of Vp/V, preceding moderate earth-
quakes at Garm in the USSR. A less well defined
depth anomaly occurred from October to December
of 1971, preceding the Limekiln Road earthquake
swarm of December 1971 and the magnitude 5.0
Melendy Ranch earthquake of February 1972. The
observed depth anomalies can be attributed to dila-

 

GEOLOGICAL SURVEY RESEARCH 1975

tancy biasing of hypocenters, although true vertical
migration of seismicity cannot be ruled out.

Using an array of fourteen 2—component borehole
tiltmeters located near the San Andreas fault in
central California, M. J. S. Johnston and C. E. Mor-
tensen learned some details of the form of crustal
deformation associated with small to moderate
strike-slip earthquakes (M =2.5 to 5). To date, pre-
cursors in tilt magnitude and direction have been
observed before more than 10 earthquakes or groups
of earthquakes, and no similar effect has yet been
seen without the occurrence of an earthquake. In-
stallations in other tectonic settings (Alaska and
southern California) are providing data to test
models of the earthquake mechanism developed with
data from the central California test section.

A magnitude 5 earthquake on Thanksgiving Day,
1974, in the midst of the heavily instrumented cen-
tral San Andreas fault zone near San Juan Bautista
provided the first observations of several different
types of precursory signals for the same earthquake.
Both tilt and magnetic field precursors were ob-
served, and a possible preearthquake velocity de-
crease is also currently being investigated.

Laboratory experiments by J. D. Byerlee provided
observations relevant to several mechanisms pro-
posed to account for precursory earthquake phe-
nomena. Byerlee observed that under differential
stress the permeability of granular materials is an-
isotropic, this condition introducing an additional
complication into precursory mechanisms requiring
fluid flow. However, it was also observed that pre-
failure velocity changes may occur even if the rock
is dry throughout the strain cycling.

Crustal strain studies

J. C. Savage and W. H. Prescott analyzed geodetic
data in the region of the 1872 Owens Valley, Calif,
earthquake in order to determine the current rate of
strain accumulation there. Right-lateral deforma-
tion since 1934 across the valley is occurring at a
rate of 4i1 mm/yr, with possible extension across
the valley of lil mm/yr. Repeated level surveys
show tilts equivalent to a 2.210.4-mm/yr uplift of
the western edge of the valley (that is, the base of
the Sierra Nevada scarp) relative to the center of
the valley. Although the measured deformations are
scarcely above the survey noise, they all indicate an
accumulation of strain that would be consistent with
a repeat of the 1872 earthquake.

W. R. Thatcher examined the approximately 100-
yr record (1860—1960) of triangulation surveys on

GEOLOGY AND HY‘DROLOGY APPLIED TO THE PUBLICWELFARE

the northern San Andreas fault system in order to
reconstruct the history of crustal deformation in this
region. High rates of shear straining preceded and
followed the 1906 San Francisco earthquake, and
data are consistent with an accelerated slip deep on
the fault plane prior to the earthquake and a post-
earthquake relaxation immediately beneath the seis-
mic zone following 1906. However, since about 1940
and perhaps earlier, faults to the east of the San
Andreas have played an important role in the strain
accumulation: within the data uncertainties, strain-
ing is uniform across an 80-km-wide region to the
east of the San Andreas fault in the San Francisco
Bay area; the maximum shear strain direction is
approximately parallel to the Calaveras fault and is
distinctly different from both the strike of the San
Andreas fault and the local direction of relative mo-
tion between the Pacific and North American plates.
North of San Francisco, the rate of strain accumula-
tion appears to decrease.

R. O. Burford, R. D. Nason, and P. W. Harsh used
data from the central California seismic net and
creep meter records for 1969—73 to estimate the ra-
tio between the total computed seismic slip and the
total observed surface creep along the central San
Andreas fault. In the currently most seismically ac-
tive section of the fault, 70 km southeast of San
Juan Bautista, surface creep exceeds seismic slip by
at least a factor of 30; ratios for other less seismical-
ly active segments of the fault average 1 to 2 orders
of magnitude lower.

Seismic risk and earthquake hazards reduction

Analyses completed by 16 researchers in various
Earth-science and engineering disciplines and using
existing geological and geophysical knowledge sug-
gest that seismic zonation in the San Francisco Bay
area is feasible (R. D. Borcherdt, 1975). Summary
results derived as basic tools for this regional zona—
tion include the following;

1. R. L. Wesson, R. D. Brown, Jr., E. J. Helley, K. R.
Lajoie, and C. M. Wentworth completed a map
showing active faults and delineating areas of
potential surface faulting (that is, the location
of potential sources of strong ground shaking).

2. R. A. Page, D. M. Boore, and J. H. Dieterich col-
lected attenuation data for bedrock shaking
and made estimates of peak ground motion
parameters at bedrock sites located at dis-
tances greater than 10, 20, and 40 km from
earthquakes of magnitude 5, 6, and 7,
respectively.

 

201

3. Lajoie and Helley compiled geologic data that
provide the basis for extrapolating results of
local site studies to larger areas. The purpose
of this work is to define and map groups of
geologic units significant for ground response,
liquifaction, and slope stability.

4. Borcherdt, W. B. Joyner, R. E. Warrick, and J. F.
Gibbs prepared a map showing qualitative
ground response and delineating those areas
for which site amplification of ground motion
is expected to be important.

5. T. L. Youd, D. R. Nichols, Helley, and Lajoie
prepared a liquifaction potential map showing
areas in which existent clay-free granular lay-
ers have a low, moderate, or high potential for
liquifaction.

6. T. H. Nilsen and E. E. Brabb completed a land-
slide susceptibility map that classifies areas
into five categories of relative slope stability
on the basis of landslide deposit distribution,
bedrock geology, and slope.

These six basic tools were applied along a demonstra-
tion profile for a postulated magnitude 6.5 earth-
quake on the San Andreas fault to illustrate a
methodology for seismic zonation of the San Fran-
cisco Bay area.

S. T. Algermissen and colleagues M. G. Hopper,
C. J. Langer, and A. M. Rogers prepared maps show-
ing the estimated distribution of Modified Mercalli
intensity in the regions of Salt Lake City, Utah, and
Puget Sound, Wash., for earthquakes of magnitude
7.5 and 7, respectively.

A. F. Espinosa and Algermissen surveyed the dam-
age and distribution of intensity resulting from the
October 3, 1974, magnitude 71/2 earthquake in Lima,
Peru. They find a correlation between the dominant
period of the earthquake and the damage sustained
by high-rise structures.

Joyner and A. T. F. Chen developed a new method
for calculating the earthquake response of one- and
two-dimensional soil configurations that rigorously
treats the nonlinear hysteretic behavior of soils.
Comparison with the widely used equivalent linear
method indicates that, for a thick soil column and
strong earthquake excitation, the equivalent linear
method significantly underestimates the short-period
components of motion.

Algermissen and D. M. Perkins completed a pre-
liminary seismic risk map for all of the continental
United States except California. The map depicts
horizontal ground acceleration having a 10 percent
probability of being exceeded in 50 yr (47 5—yr return

202

period peak acceleration). This kind of risk map
reflects economic risk better than previous maximum
intensity maps, which do not explicitly take earth-
quake occurrence rates into account. For example,
three areas, each appearing in zone 3 (maximum
risk high intensity, heavy damage expected), now
have the following extreme accelerations: Charles-
ton, S.C., 0.1 to 0.2 9; New Madrid, Mo., 0.2 to 0.4 g;
and western Nevada, 0.4 to 0.6 g.

GEOLOGIC STU DIES

Possible active fault in Ventura

R. F. Yerkes and A. M. Sarna-Wojcicki mapped a
prominent linear topographic scarp about 10 km long
and up to 12 m high trending east-west along the hill
front immediately north and east of Ventura, Calif.
This feature is inferred to be a fault-line scarp
formed by reverse-oblique displacement on a north-
dipping frontal fault because:

1. It is located at the steep southern front of one of
the east-trending Transverse Ranges, directly
analogous to the scarp of the San Fernando
fault, and on trend with a known active fault,
the Pifas Point fault, previously mapped for
more than 20 km in the eastern Santa Barbara
Channel, where it displaces Holocene deposits
but not the sea floor and has an apparent ver-
tical separation of about‘25 m up on the north.

2. The hill front immediately north of the scarp is
underlain by uplifted, tilted, and faulted upper
Pleistocene marine and nonmarine terrace
deposits.

3. Steeply dipping older Pleistocene strata of the
hill front locally exhibit tight folds having
near-vertical axes.

Larger drainages are deflected at the scarp.

At one locality, a well-developed, buried (Sanga-
mon?) soil with a thick oxidized B horizon is
sharply flexed just north of the scarp and is not
present south of it. At another locality, a
younger soil is less sharply flexed near the
scarp; since this latter soil is developed in a
Holocene(?) fan, its deformation may reflect
Holocene movement at depth.

6. The scarp cannot be explained by erosion related
to present-day drainage. The scarp is modified
by erosion, cultivation, and construction and
locally may be buried by very young stream de-
posits. Although unequivocable evidence of
Holocene displacement has not been found, the
fact that the scarp postdates the emergence of

9"!“

 

GEOLOGICAL SURVEY RESEARCH 1975

a low marine terrace in this area of continuing
seismicity indicates that its age and activity
should be thoroughly investigated.

Holocene movement on the Garlock fault

The Garlock fault, a major left-lateral fault in
southern California, trends northeast to east for a
distance of about 250 km. Its total displacement is
estimated to be about 65 km. The fault trace provides
abundant evidence of geologically recent activity, but
no historic displacements have been recorded. Where
its trace lies along the southern edge of Searles and
Panamint Valleys, alluvial and lacustrine sediments‘
of late Quaternary age are offset. Near Christmas
Canyon in Searles Valley, stratigraphic and geomor-
phic relations noted by G. 1. Smith suggest that two
horizontal displacements totaling 8 m have probably
occurred during the last 10,000 yr. The fault in that
area consists of a single trace that has a zone about
15 cm wide dipping steeply to the south. The older of
the two displacements cuts lacustrine gravels esti-
mated to be 10,000 yr old or older and was probably
covered by alluvial gravels, estimated by strati-
graphic correlation with dated subsurface sediments
to have ceased deposition 6,000 to 8,000 yr ago. The
younger of the two displacements cuts those alluvial
gravels but is covered by others that are probably a
few hundred but not more than about 2,000 yr old.

Along the southern end of Panamint Valley '(30 km
east of the Christmas Canyon area), the Garlock
fault last displaced a thin alluvial unit tentatively
correlated with deposits in Searles Valley estimated
to be about 2,000 yr old. If displacements in both
areas occurred at the same time, these relations sug-
gest that the next—to—the-last offset occurred 6,000
to 10,000 yr ago and that the last offset occurred
between a few hundred and 2,000 yr ago. The sum of
the two horizontal displacements is 8'm. If the last
displacement were so recent that little or no strain
has accumulated, the implied rate of strain accumu-
lation is 0.8 mm/yr. However, if the last displace-
ment occurred at about the same time that the
younger alluvial gravels were deposited (about 2,000
yr B.P.), then the implied rate of strain accumula-
tion would be E1 mm/yr.

Late Quaternary faulting in coastal California

Mapping of Quaternary features along the San
Mateo County coastline by K. R. Lajoie, G. E. Weber,
and J. C. Tinsley III documented the type and age of
movements along a major fault zone that branches
off the San Andreas fault at Bolinas Lagoon north

GEOLOGY AND HYDROLOGY APPLIED TO THE PUBLIC WELFARE

of the Golden Gate and extends 150 to 200 km south-
southeast subparallel to the California coastline. In
the vicinity of Point Sur, south of Monterey, it is
represented by the Palo Colorado fault. The fault
zone lies offshore for most of its length but transects
the San Mateo County coastline for 4 km north of
Half Moon Bay, where it is called the Seal Cove fault,
and for 26 km between San Gregorio and Point Afio
Nuevo, where it is called the San Gregorio fault. De-
formed emergent marine terraées record general
movements to about 0.5 to 0.7 m.y. B.P., and de-
formed Holocene deposits document very recent dis-
placement. Seismic activity along the seaward exten-
sion of this fault zone south of Point Afio Nuevo
documents modern activity.

Four strands of the San Gregorio fault zone, ex-
posed in the sea cliffs on the southern shore of Point
Afio Nuevo, offset the Sangamon wave-cut platform
and the overlying marine and alluvial deposits of the
first emergent terrace, this offset indicating move-
ment in the last 70,000 to 140,000 yr (Weber and
Lajoie, 1974). Northwest of Point Afio Nuevo, tec-
tonic movements associated with the San Gregorio
fault zone have tilted a series of at least six emergent
marine terraces. Succes-sively greater terrace de-
formation with age suggests continued movement
during middle to late Pleistocene time with north-
west tilting of the block west of the main strand of
the San Gregorio fault zone. Stratigraphic offsets
and the pattern of faulting indicate that most of the
movement along the fault‘zone is right-lateral strike
slip with smaller and variable vertical components
associated with internal defamation of the blocks
within and on either side of the fault zone.

Holocene movement is indicated on one of the fault
strands at Afio Nuevo by deformation of fluvial and
estuarine deposits along the shear zone. Charcoal
from a deformed bed of silty clay in these deposits
yields a 1“C age of 9,5101- 140 yr B.P.

Gentle folding and vertical fault offset of emergent
marine terraces at Half Moon Bay record late Pleis—
tocene tectonic movements alonga 23-km segment

of the Seal Cove fault and its offshore extension to .

the south, which joins the San Gregorio fault. The
wide, continuous lowest terrace (Sangamon?) and
the discontinuous second terrace are warped suc-
cessively more tightly into a gentle syncline that
plunges obliquely to the northwest into the fault
zone. Linear joint-controlled stream courses drain-
ing the coastal uplands are deflected toward the syn-
clinal axis as they cross the lowest terrace. Streams
crossing the downwarped part of this terrace ad-

 

203

j acent to Half Moon Bay are depositing alluvial fans,
whereas streams crossing the uplifted part of the
terrace south of the bay have incised and abandoned
their late Pleistocene flood plains, which themselves
are incised into the thick cover of marine terrace
deposits. Half Moon Bay developed as the Holocene
transgression flooded the synclinal trough formed in
the lowest terrace (Lajoie and others, 1975).

North of Half Moon Bay, the lowest terrace is
offset vertically 45 m (west side up) across the Seal
Cove fault to form the narrow linear Pillar Point
headland and ridge. North of Half Moon Bay, discon—
tinuous remnants of at least four higher marine ter-
races are offset vertically along five short fault
strands subparallel to and northeast of the Seal
Cove fault. Evidence of recent tectonic activity is a
0- to 1.5-m west-facing scarp across the Holocene
alluvial fan of Denniston Creek parallel to and 1.0 km
northeast of the Seal Cove fault.

Data on marine terraces along the entire western
coast of the United States being compiled by B. R.
Hamachi and P. A. McCrory will» serve as the basis
for an expanded coastal tectonics project. Data on
tectonic movements recorded in the deformation of
late Pleistocene emergent terraces and in the region-
al variability of deposits formed by the Holocene
transgression probably can be integrated with and
provide background for other coastal’tectonic proj-
ects, such as regional studies of active faults by J. I.
Ziony, J. M. Buchanan-Banks, and E. H. Pampeyan
and studies of present crustal movements using geo-
detic and tide-level data by R. 0. Castle.

Field studies related to the preparation of geologic
environmental maps of coastal California have veri-
fied the existence of late Quaternary faulting in two
areas where information was previously lacking or
little known. One area, between the Newport-Ingle-
wood fault in southern California, was defined by
Ziony, C. M. Wentworth, Buchanan-Banks, and
H. C. Wagner (1974) on a 1E250,000-scale map de-
signed to show the tectonic environment of coastal
southern California from Mexico to Point Arguello. A
second area lies near San Luis Obispo, in central
coastal California, where detailed geologic mapping
by C. A. Hall, Jr. (1973a, b, 1974) , and reconnaissance
by Pampeyan defined a northwesterly trending
zone as much as 2 km wide and 120 km long, in which
Pleistocene deposits are offset. The Edna fault, a
west-northwest—trending fault with probable strike-
slip displacement, is near the southern end of this
zone. At the northern end is an unnamed set of
northwest-trending lineaments, evidenced onshore

204

near San Simeon by several prominent parallel val-
leys, along which stream channels are offset in a
right-lateral sense. Offshore, this set of lineaments
appears to control the coast between Cape San Mar-
tin and Point Estero. However, with the offshore
data presently available, no simple clear-cut connec-
tion can be found. If the ends do not define a single
continuous zone of strike-slip faulting, they are at
least parts of a larger system along with the offshore
Hosgri fault. The geometry and tectonic environ-
ment in this area are significant in land-use planning,
because tectonic elements in the zone are close to
(less than 12 km) a proposed deepwater supertanker
port facility and a nuclear powerplant.

Seismic response studies in San Francisco Bay region

Geologic maps of upper Quaternary unconsolidated
deposits in the San Francisco Bay region by E. J.
Helley and K. R. Lajo-ie provided the basis for inter-
preting and extrapolating seismic velocity data (P
and S) in a study to predict how each geologic unit
in the alluviated flatlands will respond in a local
earthquake and how the entire alluviated area will
respond relative to the surrounding bedrock terrane.

Results of a preliminary study by J. F. Gibbs,
R. E. Warrick, T. E. Fumal, R. D. Borcherdt, Lajoie,
and L. T. Youd showed that the average seismic
velocities (P and S in metres per second) over a 0- to
30-m depth interval range from 1,500 and ‘90, re—
spectively, for the Holocene Bay mud to 1,670 and
380 for saturated upper Pleistocene alluvium, to
1,850 and 490 for Pliocene sandstones, to 2,700 and
275 for greenstone of the Franciscan Formation
(Cretaceous part), and to a maximum of 3,900 and
1,450 for the deeply weathered granodiorite of Mon-
tara Mountain. Results to date indicate that shear-
wave velocities correlate with seismic amplitude re-
sponses determined from nuclear explosions and the
1906 earthquake intensities. Preliminary data indi-
cate that the differences in seismic velocities and
engineering properties between Holocene and upper
Pleistocene alluvium are significant only where these
units lie above the water table. Upper Pleistocene
alluvium in the lower parts of the bay basin, adja-
cent to and beneath the bay, probably has never been
dessicated and therefore shows no signs of precon-
solidation. In higher parts of the alluvial plain sur-
rounding the bay, upper Pleistocene alluvium has
probably been above the water table throughout
much of its history and is therefore preconsolidated.
In these areas, overlying Holocene alluvium is not
yet preconsolidated, so its physical properties are

 

GEOLOGICAL SURVEY RESEARCH 1975

different from those in the upper Pleistocene alluvi-
um. Test sites are being selected to investigate the
role of depth to ground-water table on seismic re-
sponse characteristics.

History of recent movement on the Elsinore fault

Recent field investigation by M. M. Clark (1975)
showed that right laterally offset drainages occur at
several places along the 150-km section of the Elsi-
nore fault zone that lies in Imperial and San Diego
Counties. However, fault-offset topographic features
are either greatly eroded or missing entirely from
much of this southeastern part of the fault zone.
Only in a 15 km-long section at the common county
line does the fault show the impressive continuity of
very recently offset alluvial surfaces and channels
that is typical of active parts of the San Andreas and
San Jacinto faults. Southeast of this section and
northwestward through Mason Valley, the fault zone
is marked by either well-eroded or very discontinu-
ous horizontal and vertical offsets of the ground sur-
face. Northwest of Mason Valley, most of the re-
maining 70 km of the fault zone in San Diego County
is characterized by fault topography that either no
longer preserves the amount of original offset or is
entirely of erosional origin rather than tectonic
origin.

In the 30-km interval immediately northwest of
the common county line, recent movement has oc-
curred only along a subparallel group of normal
faults that lie 3 to 4 km to the northeast of the pro-
j ected trend of the otherwise straight Elsinore fault
zone.

This spotty distribution of evidence for recent
movement along the southeastern part of the Elsi—
nore fault zone, combined with the presence of active
faults to the northeast between the Elsinore and San
J acinto fault zones, suggests that recent release of
crustal strain in this region has complex distribution
and, perhaps, timing. Release of strain is not con-
centrated uniformly along the southeastern part of
the Elsinore fault zone.

Earthquake recurrence intervals from deformational structures

in young lake sediments

Examination of the silty sediments in the Lower
Van Norman Reservoir after the 1971 San Fernando,
Calif., earthquake revealed three zones of deforma-
tional structures in the 1-m-thick sequence of sedi-
ments exposed over about 2 km2 of the reservoir bot-
tom. These zones are correlated with moderate earth-
quakes that shook the San Fernahdo area in 1930,
1952, and 1971. The success of this study, coupled

GEOLOGY AND HYDROLOGY APPLIED TO THE PUBLIC WELFARE

with the experimental formation of deformational
structures similar to those from Van Norman Reser-
voir, led to a search for similar structures in Pleisto-
cene and Holocene lakes and lake sediments in other
seismically active areas. Thus, studies have been
started by J. D. Sims in Pleistocene and Holocene
silty and sandy lake sediments in the Imperial Valley
in southeastern California, in Clear Lake in northern
California, and in the Puget Sound area of
Washington.

The Imperial Valley study has yielded spectacular
results: five zones of structures in the upper 9 m of
upper Holocene sediments of ancient Lake C‘ahuilla
near the Imperial fault 3 km south of Brawley have
been correlated over an area of approximately 100
km2 by using natural outcrops (Sims, 1974). These
structures are similar to those of the Van Norman
Reservoir and are interpreted to represent at least
five moderate to large earthquakes that affected the
southern Imperial Valley area during late Holocene
time. Eleven holes were drilled and sampled continu—
ously in these ancient lake sediments. The holes
range in depth from 11 to 26 m and extend the
knowledge already gained from limited outcrops at
least threefold. Examination and analysis of these
cores are now underway.

The Clear Lake study has provided ambiguous re-
sults with respect to the determination of earthquake
recurrence intervals because the cores studied are in
clay-rich organic sediments that have low liquefac-
tion potential (Sims and Rymer, 1975).

A study of upper Pleistocene varved glaciolacus-
trine sediments has been started in the Puget Sound
area of Washington, and 13 sites have been exam-
ined. One has yielded 18.75 m of sediments that con-
tain 1,804 varves and 14 deformed zones interpreted
as being caused by earthquake because they are
identical to structures formed experimentally by
simulated seismic shaking. These structures have
been used to construct a preliminary earthquake his-
tory for the Shelton, Wash, area (Sims, 1974). This
history shows two episodes of earthquake activity.
The first period of earthquake activity lasted about
400 yr and consists of six subequally spaced earth-
quakes. A second episode lasted about 900 yr and
consists of five subequally spaced earthquakes.

Correlation of deformation structures with seis-
mic events is based .on (1) proximity to presently
active seismic zones; (2) presence of potentially
liquefiable sediments; (3) similarity to structures
formed experimentally; (4) small-scale internal
structures within deformed zones that suggest lique-

 

205

faction; (5) structures restricted to single strati-
graphic intervals; (6) zones of structures correlat-
able over large areas; and (7) absence of detectable
influence by slopes, slope failures, or other sedimen-
tological, biological, or deformational processes.

Metagraywacke in the Salinian block—recantation and
reevaluation

Field studies by D. C. Ross showed that the meta-
graywacke terrane in the Santa Lucia Range of Cali-
fornia is intruded along its western side by Meso-
zoic granitic rocks. Thus, Ross’s previous sugges-
tion—that the western contact of the metagraywacke
marked a significant strike-slip fault zone—must be
abandoned.

Nevertheless, this lithologically distinctive belt in
the Salinian block, extending across Salinas Valley,
is structurally significant as a ‘,‘barrier” against
strike—slip movements in the area and thus counters
a previous suggestion of Ross and Brabb (1973).
The metagraywacke also limits strike slip on the
northern extension of the Rinconada fault zone of
Dibblee (1972).

The metagraywacke belt and other bedrock rela-
tions in the Gabilan and Santa Lucia Ranges suggest
a coherent basement block without significant strike-
slip displacement from the San Andreas fault west as
far as the Palo Colorado fault on the western flank
of the Santa Lucia Range. Anyone proposing models
of Salinian block reconstruction should note that
“slivering” of the Salinian block at this latitude, or
continuation northward of the Rinconada strike-slip
fault zone, must occur west of this block.

Influence of bedrock structure on seismicity

Analysis of the San Andreas fault system in cen-
tral and northern California by W. P. Irwin resulted
in the discovery of a close relationship between re-
gional geologic structure and seismic behavior.
“Locked” fault segments have little seismic activity
between occasional earthquakes of large magnitude,
whereas other segments are highly active and are
characterized by frequent earthquakes of small mag-
nitude and by creep. The principal locked segment is
the main strand of the San Andreas fault from near
San Juan Bautista northward to beyond Point
Arena; a second locked segment extends southward
from Cholame. The active segments include (1) the
San Andreas fault southward from near San Juan
Bautista to Cholame and (2) the Sargent, Calaveras,
and Hayward faults in the San Francisco Bay
region.

206

The significant aspect of the regional geologic
structure is the remarkably close correlation between
the truncated end of the upper plate of the Coast
Range thrust and the zones of creep and frequent
small-scale seismicity along the San Andreas, Hay-
ward, and Calaveras faults. The faults tend to be
highly active Where they regionally cut the upper
plate, which consists of rocks of the Great Valley
sequence, but-they are locked elsewhere. In this
structural model, serpentinite, which occurs locally
along the base of the Great Valley sequence, is in con—
tact with the segments of the faults that cut the
upper plate and is perhaps plastically injected and
sheared along the faults by right-lateral drag.

Another possibly related factor affecting seis-
micity is the distribution of springs in the Francis-
can metamorphic terrane, which Irwin studied joint-
ly with Ivan Barnes. Where Franciscan rocks are
capped by the upper plate of the Coast Range thrust,
water from metamorphic rocks may migrate to the
faults that cut the upper plate; this water may
fill and lubricate the fractures in dilated rocks and
thereby cause continuous creep rather than allow
large strains to accumulate. The terrane cut by the
principal locked segment of the San Andreas fault
in northern California is devoid of springs that de-
rive water from metamorphic rocks.

Fault scarp morphology as a key to age

R. E. Wallace’s study of historic and older fault
scarps in north-central Nevada, such as those formed
during the 1915 and 1954 earthquakes and those
formed before and after the high stand of glacial
Lake Lahontan (12,000: yr), showed progressive
degradation accompanied by a decrease in maximum
slope angle. Historic scarps have two major slopes:
the upper slopes (free faces) range from 60°.to
overhanging, whereas the lower slopes (debris
slopes) have maximum angles of about 35°. In some
places, the two different slopes may persist for more
than 1,000 yr. The maximum slopes of scarps older.
than 12,000 yr are concentrated in the 7° to 20°
range, and those of scarps younger than 12,000 but
older than a few thousand years are in the 15° to 35°
range. Other characteristics, such as the curvature
of the scarp crest and the ratio of free face to debris
slope, are also age criteria.

Analysis of scarp geomorphology indicates re-
peated movement on some faults, such as the 1915
earthquake fault, and suggests recurrence intervals
for major displacements measured in thousands of
years.

 

GEOLOGICAL SURVEY RESEARCH 1975

ENGINEERING GEOLOGY

Slope stability investigations

What is probably the largest known landslide in
the United States caused by lateral spreading (a
result of liquefaction) was discovered 16 km north
of Salt Lake City, Utah, by Richard Van Horn. Two
such landslides occur in Davis County, Utah, be-
tween Farmington and Great Salt Lake and comprise
the area named the Farmington Siding landslides.
The younger slide covers about 9 km2 and is proba-
bly less than 2,000 yr old. The older covers at least
8 km2 and is between 2,000 and 5,000 yr old. An
unknown amount of the older landslide lies hidden
under the younger.

The Farmington Siding landslides contain longi-
tudinal ridges, undrairred depressions, and distinc-
tive internal structures indicating sliding, shearing,
and liquefaction. A preliminary version of a new
topographic map of Great Salt Lake and vicinity re-
vealed seven other areas around the lake that have
topographies similar to the topography of the Farm-
ington Siding landslides. Thus, landslides of this
type may be common near Great Salt Lake, and land
users and land-use planners should develop an
awareness for potential landslides on the gently
sloping plains surrounding Great Salt Lake.

Reports from the 1906 San Francisco earthquake
and other northern earthquakes were reviewed, and
incidents of ground failure described therein were
identified, classified, and tabulated and their loca—
tions plotted on modern maps by T. L. Youd and
S. N. Hoose. The results were used to (1) further
identify and clarify the types of ground failure asso-
ciated with earthquakes; (2) provide a guide to
engineers, planners, and others responsible for mini-
mizing seismic hazards; and (3) form a data base
for further geotechnical studies of earthquake-trig-
gered ground failure.

Liquefaction-induced lateral spreading of recent
flood-plain deposits and filled areas, particularly in
the city of San Francisco, is among the most common
and most destructive types of ground failure trig-
gered by earthquakes in northern California. Hill-
side landslides on steep slopes, such as coastal bluffs,
also are a very common and very destructive type of
ground failure. .

Continued studies by D. H. Radbruch-Hall of the
gravitational creep of rock masses indicate that
large-scale slope movement of this type may be wide-
spread in the United States, especially in mountain-
ous regions. This type of slow landsliding, in which

GEOLOGY AND HYDROLOGY APPLIED TO THE PUBLIC WELFARE

zones of creep can extend more than 100 m below the
surface, is distinct from more well-known types of
movement of surficial material, such as solifluction
and debris flows.

Since large-scale gravitational creep may change
to sudden catastrophic slide movement, recognition
and understanding of this phenomenon are vital in
site selection for and design of major engineered
structures, particularly in high mountains. In places
where valley sides are moving horizontally or bulg-
ing outward, engineered structures in the valley bot-
tom will be subjected to both upward and lateral
pressures, owing to the bowing up of the valley bot-
tom or the closing in of the sides.

Large-scale rock creep on slopes has been observed
and described by various investigators, including
Radbruch-Hall, in different parts of the world:
Europe, New Zealand, Iran, South America, and the
United States. Measured rates of such movement
range from 2 cm/yr to 20 cm/d.

Creep proceeds in several different ways in differ-
ent geologic settings; (1) By valleyward extrusion
of weak ductile rocks overlain by, or interbedded
with, more rigid rocks, resulting in tension fractur-
ing and outward movement of the more rigid rocks
as well, sometimes with upward bulging in the cen-
ters of valleys; (2) by distortion and buckling of
dipping, interbedded strong and weak rocks or by
creep of rigid rocks over soft rocks without buck-
ling; (3) by movement distributed over a thick zone
in relatively uniform material; (4) by deep—seated
bending, folding, and plastic flow of rocks on slopes;
(5) by incremental movements along a dipping
rough-surfaced plane; and (6) by bulging, spread-
ing, and fracturing of steep-sided ridges in moun-
tainous areas. There may be still other types of creep.
that have not yet been recognized.

Some of these different types of gravitational
creep occur in the United States in the Allegheny
Plateau region, in Utah, in Yellowstone National
Park, in northern New York State, in California, in
the Olympic Mountains of Washington, in Alaska,
and in the Rocky Mountains of Colorado.

Research in rock mechanics

Strain data obtained in laboratory and field experi-
ments by T. C. Nichols, Jr., and F. T. Lee (USGS)
and J. F. Abel (Colorado School of Mines) indicated
that large amounts of energy can be concentrated
and stored within rock masses and that such energy
is available for release. Strains resulting from ener-
gy release were measured on surfaces of individual

 

207

rock specimens cut under conditions that isolated the
specimen from strain-inducing confining pressure
or temperature conditions. The igneous rock speci-
mens tested released strain energies that measured
more than 1X103 ergs/cm3 and, in some specimens,
as much as 1X 10G ergs/cmg. These strains, measured
on the specimen surfaces, were produced from inter-
nal energy and were dependent on the original size
and shape of the rock. The strain was released both
as instantaneous energy and as energy released over
a longer period of time. The amount of energy meas-
ured was similar to those amounts, previously esti-
mated by other investigators, that were released
during rock bursts in similar rocks. Therefore, the
present investigators suggest that surface and un-
derground burst failures in large part are due to
internal energy released by natural or manmade
changes in the geometry of rock masses. The deter—
mination of internally stored energy may be critical
for the design of mining operations, either above or
below ground.

Release of stored energy in large rock masses
might cause rock failures and some moderate-sized
earthquakes.

Coal mine subsidence studies conducted in the
Somerset coal mining district of Colorado during the
past 2 yr by C. R. Dunrud reVealed that the stresses
produced by subsidence in moderately deep to deep
overburden above room—and-pillar mine workings
control, in a significant way, stress levels in the mine
workings as well as disruption of the ground surface.
Analyses of subsidence measurements and deforma-
tional features mapped at the surface and within the
mine workings show that the process-es of subsidence
comprise two different stress and yield conditions in
response to the excavation of mine workings. First,
arcuate zones of compressive stress, called compres-
sion arches, tend to develop above and below the
mine workings and to transfer the overburden load
to adjacent solid coal or barrier pillars. Second, the
strata within these arches tend to cave and flex
downward or heave upward and increase the stresses
in the mining area again and reduce them on adja-
cent barrier pillars or solid coal boundaries.

With time, the compression arches migrate up-
ward into the superj acent strata and downward into
the su-bjacent strata; this movement further in-
creases the stresses in the mining areas and reduces
them on the barrier pillars or mine boundaries. The
arches may eventually migrate to the ground surface
and cause compression fracturing or overthrusting.
This activity is commonly followed by local tension

208

fracturing and further compression failure as a re-
sult of the downward flexing of strata into the mine
workings. This fracturing can threaten other valua-
able deposits in the overburden, the surface environ-
ment, or the works of man. The rate of migration
of the compression arches, and consequently the rate
of stress transfer or time before the ground surface
is affected, is controlled by the thickness of the over-
burden, the strength of the overburden and the
strata below the mine workings, the rate and se-
quence of mining, and mine geometry. Mine safety
and coal production could therefore be increased if
the geologic and engineering factors affecting subsi-
dence were better known. Companies mining the coal
stand to benefit from subsidence research as much as
those concerned with protecting the environment.

Research in soils engineering

Work on the engineering characteristics of hillside
materials in the San Francisco Bay region by C. M.
Wentworth, S. D. Ellen, and others yielded new
promise for an old test for swelling clays. Numerous
methods are used by civil engineers to evaluate the
expansiveness of soils and clayey rocks, but most are
too expensive for reconnaissance work, and simpler
tests either have not been effectively correlated with
field performance or have been considered too crude.

However, extensive reconnaissance fieldwork and
simple and inexpensive measurements of the free
swell (Krynine and Judd, 1966, p. 144) of hundreds
of samples indicate (1) that a wide range of free
swell values is obtained from various geologic units
in the bay region (<20 to 200 percent swell) and (2)
that material shown by field evidence to shrink or to
become sticky or tough when wet to moist yields free
swell values above a threshold of about 50 percent.
Careful testing in a commercial laboratory of 25
samples representing the range of free swell values
encountered demonstrates that free swell values cor-
relate well with loaded swell values (which are ac-
cepted by civil engineers).

Reconnaissance field observations and the simple
free swell test thus can be used as an indication of
the likelihood that material is expansive (of suffici—
ent swell potential to damage roads, slabs, or light
structures) and may be a useful guide to the magni-
tude of swell potential as well.

Engineering-geologic reports used by government and
nongovernment agencies
During the past year, 13 Veterans Administration
hospital sites were evaluated geologically by T. C.
Nichols, J r., as a continuation of an evaluation pro-

 

GEOLOGICAL SURVEY RESEARCH 1975

gram begun after the 1971 San Fernando, Calif,
earthquake. Eleven of these sites were examined
briefly in the field. Administrative reports for all
sites were transmitted to the Veterans Administra-
tion; the potential geologic and earthquake hazards
that might affect the future safety of the hospital
buildings and patients were delineated.

USGS geologic maps and reports on the geology
and water resources of the Anchorage, Alaska, area,
such as the one by Chester Zenone, H. R. Schmoll,
and Ernest Dobrovolny (1974), have been used
by the Planning Department of the Greater Anchor-
age Area Borough in a variety of ways, ranging from
subdivision review and analysis to the preparation
of a comprehensive plan for the development of the
entire borough. A subdivision ordinance on hillside
development requires in-depth review of the effects
of topography, geology, hydrology, and engineering
where the terrain has slopes in excess of 25 percent.
On more gently sloping ground, subdivision develop-
ment conforms to geologic and hydrologic con-
straints. The comprehensive plan provides guidelines
for certain long-range projections of community
needs, including (1) development of additional
water-supply facilities; such as damsite locations,
and reservation of land for artificial ground—water
recharge; (2) location of sites for waste disposal;
and (3) selection of open-space areas.

A request for the release of results of testing of
physical properties of soils and-rocks was received
from Purdue University’s National Rock Informa-
tion Center. Data obtained from such testing in the
Engineering Geology Laboratory under the direction
of R. A. Farrow were entered into a file coded on
magnetic tape. A copy of this tape, a description of
the coding scheme, and results of the testing were
released to the public through the National Technical
Information Service (Farrow and Chleborad, 1974) .

STUDIES RELATED TO LAND USE
AND ENVIRONMENT

Earth‘science studies oriented to land use and
environment resulted in a broad spectrum of reports
and maps that discuss and depict geologic hazards,
influences of geologic conditions on man’s utilization
of the environment, and basic data for land-use
decisionmakers.

GEOLOGY AND HYDROLOGY APPLIED TO THE PUBLIC WELFARE

URBAN GEOLOGIC STUDIES

Tunneling conditions for 34 urban areas surveyed

In studies of 34 urban areas, E. M. Cushing and
R. M. Barker found that the most common ground
condition was one of hard bedrock underlying less
consolidated materials at depths of less than 80 m
and that bedrock at depths of 15 m or less was the
prevailing condition in 21 areas. Of the areas
studied, soft-ground tunneling conditions to depths
of more than 80 m occur only at Houston, Memphis,
and New Orleans. Ground water is everywhere close
to the land surface in the Fort Lauderdale, Miami,
and New Orleans areas. In most other urban areas,
ground-water conditions are complex, and both wa-
ter-table and artesian conditions exist within 80 m of
the land surface.

“Special features” that would affect construction
and maintenance of tunnels include flood-prone
areas, buried alluvium-field stream channels, solution
cavities, active faults, and deeply weathered bedrock.
Each American urban area differs geologically and
hydrologically from all others; only the Dallas-Fort
Worth and Fort Lauderdale-Miami areas are similar
in any considerable way.

This information was compiled from existing
sources during a study funded by the US. Depart-
ment of Transportation and is included in an ad-
ministrative report submitted to that agency.

Land-use information needs being met in Colorado Front Range
urban corridor

Studies along the Front Range urban corridor of
Colorado, centered on Denver, proceeded down sev-
eral avenues of land use, urban mineral resources,
and urban hydrology. Enactment of land-use legisla-
tion by the Colorado legislature in 1974 and a grow-
ing environmental awareness on the part of the pub-
lic have resulted in a-large demand for products of
the urban study. A map showing mined areas in the
Boulder-Weld coalfield by R. B. Colton and R. L.
Lowrie was quickly sold out and was reprinted to
meet the continuing demand. Maps showing gravel
resources by Colton, D. E. Trimble, and H. R. Fitch
have been popular with community leaders and land
developers as Well as with gravel operators. Maps
recently released by J. F. McCain and W. R. Hotch-
kiss show flood-prone areas and are expected to have
widespread and immediate applications for a wide
spectrum of users. Maps showing the kinds and sites
of hydrologic data by E. R. Hampton and the loca-
tion and quality of water in lakes by T. W. Danielson

 

209

in the greater Denver area will aid water—resource
and land-use planners and managers.

Mountain soils mapping in Front Range urban corridor

The suitability of mountain areas along the Colo—
rado Front Range as sites for the works of man de—
pends partly on the thickness and engineering prop-
erties of the soil. 'K. L. Pierce and P. W. Schmidt
studied the distribution, thickness, and character of
mountain soils (including saprolite and transported
alluvium-colluvium) as they relate to urbanization.
Drafts of seven quadrangle maps at a 1:24,000 scale
were enthusiastically received by planners. Studies
continued in other quadrangles.

Maps are prepared on the basis of geologic recon-
naissance, water-well logs,‘ airphoto interpretation,
refraction seismology, and regional geomorphic relap
tionships. Map units are selected on the basis of their
potential usefulness to planners, developers, and land
owners. They consist of five simple soil ter-rane
units: mostly soil, soil with subordinate rock, rock
with subordinate soil, mostly rock, and alluvium.
Each unit within a given area is defined by the ratio
of soil or weathered rock to hard bedrock. Alluvium
is used as a separate mapping unit because of its dis-
tinctive lithology.

Liquefaction map put to use in San Francisco Bay area

A preliminary map of the liquefaction potential of
unconsolidated sediments prepared for the southern
part of the San Francisco Bay region has been wide-
ly used in the preparation of environmental impact
reports and city and county seismic safety elements.
Seismic safety elements describe seismic and geo-
logic hazards that may affect a given community and
establish goals and policies for dealing with these
hazards.

The map was prepared by T. L. Youd, D. R. Nich-
ols, E. J. Helley, and K. R. Lajoie. Map zones are
established on the basis of detailed geologic mapping.
Liquefaction potential for each zone is estimated
from an analysis of lithologic, water-table, and
standard penetration test data. Sediments found to
have the highest potential for liquefaction are clean
granular deposits (Holocene in age) that lie within
the younger bay sediments and within flood-plain
deposits. Other Holocene deposits generally have
moderately low potential for liquefaction. Pleisto-
cene deposits in the region have a generally low
liquefaction potential.

210

ENVIRONMENTAL GEOLOGY OF CITIES
AND COUNTIES

Thickness of overburden in Fairfax County, Virginia ‘

Preliminary analysis of the thickness of the ‘over-
burden in Fairfax County by A. J. Froelich and A. E.
Nelson based on water-well and construction data
and field studies indicates that residuum on Triassic
sedimentary rocks in the western part of the county
rarely exceeds 6 m; saprolite on Piedmont crystalline
rock in the central upland part of the county locally
exceeds 50 m; unconsolidated Coastal Plain and
younger upland deposits in the eastern part of the
county form an eastward-thickening prism more
than 100 m thick. Fresh bedrock is commonly ex-
posed along stream valleys in the Triassic and Pied-
mont crystalline areas and locally crops out through
upland surfaces underlain by quartz bodies and ul-
tramafic and mafic rocks. Each type of overburden
has radically different physical, chemical, and min-
eralogical properties that strongly influence land-use
and development capabilities.

Computer mapping for environmental planning

A computer mapping system using cell-formatted
storage, analysis, and display has been used to com-
bine existing geologic, hydrologic, and other physical
information for environmental analyses of Mont-
gomery County, Md. Working with county environ-
mental planners, J. N. Van Driel produced computer-
composite maps showing the occurrence and dis-
tribution of shallow bedrock, unstable surface ma-
terials, steep slopes, surface water, mature trees,
and other factors considered by planners to be lim-
itations to various types of urban development.
These composite maps have been received enthusi-

astically by the county and are being used as the-

basis for drafting area development plans and also
as a standard for determining the environmental
consequences of established plans.

Geology-related problems at Memphis, Tennessee

W. S. Parks (USGS) and R. W. Lounsbury (Mem-
phis State Univ.) found that urbanization and in-
dustrialization of the Memphis area commonly re-
sult in geology-related problems. These problems are
associated with foundation materials, aggregate sup-
plies, flood hazard, water supply, solid waste dis-
posal, and earthquake risk. Consideration of these
topics as parts of an overall problem in environmen-
tal management provides an insight into their close
interrelations and points out the need for coordi-

 

GEOLOGICAL SURVEY RESEARCH 1975

nated studies of the geology and hydrology of the
area.

Earth materials in Memphis are suitable for the
foundations of residences and light buildings in most
places. Site investigations are necessary to deter-
mine the bearing capacities of the materials for
heavy construction and high—rise buildings. Aggre-
gate supplies are abundant in the immediate vicinity
of Memphis and in outlying areas. Nevertheless, the
high cost of land and zoning restrictions could be-
come significant factors in their continued develop-
ment and use. Flood hazard is an immediate local
problem where fills and excavations are rapidly con-
stricting or altering the natural flood plain of small
creeks and rivers. Both ground- and surface-water
resources are abundant, but contamination by leak-
age and land subsidence could result from continued
increases in annual withdrawals from the major
aquifer. Earthquake risk was proven to exist in the
Mississippi River valley by the New Madrid earth—
quakes in 1811 and 1812 and by the large number of
shocks that have occurred since. Knowledge of the
expected magnitudes, frequencies, and destructive
effects of earthquakes in the Memphis area is at best
rudimentary. Some information is now being col-
lected with seismographs at Memphis and in the
immediate vicinity.

Landslides and other disturbed ground in Allegheny County,
Pennsylvania

Forty-three maps at 1:24,000 scale prepared by
J. S. Pomeroy and W. E. Davies in cooperation with
the Appalachian Regional Commission include the
1,890 km2 of Allegheny County and show landslides,
mine-related features (strip mines, dumps, subsi-
dence evidence), cuts, fills, excavations, and recent
land modifications for housing and other develop-
ment. Over 2,200 prehistoric and approximately 800
recent (historic and active) landslide deposits are lo-
cated, and the maps also show the outlines of the
zones considered most susceptible to slope failure on
the basis of landslide incidence, rock and soil materi-
als, topography, and other parameters. About 83 per-
cent of Allegheny County’s recent landslides occurred
in soils and weathered rock derived from the 180- to
200-m-thick Conemaugh Group, the highest percent-
age of slope failure taking place in the upper half of
the unit.

The maps are expected to be used as the areal basis
for preparation of model zoning ordinances or for
other land-use management guidance by the Alle-
gheny County Department of Planning and Develop-

GEOLOGY AND HYDROLOGY APPLIED TO THE PUBLIC WELFARE

ment. This department has figures showing that
landslide damages in the county may average
$2,000,000 a year.

COASTAL ENVIRONMENTAL GEOLOGY

San Mateo County, California

Old topographic maps (1851—66) , subdivision maps
(1906—10), aerial photographs (1926—41), and his-
torical ground photos (1900 ?—50) provided the basis
for establishing historic sea-cliff erosion rates in San
Mateo County. Erosion rates are plotted with lith-
ologic and physiographic data on planimetric pro-
files of the coastline in an attempt to determine fac-
tors controlling coastal erosion. Preliminary conclu-
sions are as follows:

1. The most rapid historic cliff erosion (~0.3 m/
yr) occurs Where the wave-cut platform of the
lowest emergent marine terrace (usually San-
gamon) lies at present sea level and wave ero-
sion is merely stripping unconsolidated marine
deposits from these old surfaces.

2. The least historic erosion (virtually nil) is along
segments of the coast composed of granodiorite
at Montara Mountain and the highly indurated
Pigeon Point Formation (Upper Cretaceous).

3. segments of coastline composed of unconsoli-
dated marine terrace deposits (usually Sanga-
mon) generally have low to moderate historic
erosion rates (0.1 to 0.2 m/yr) owing to dy-
namic coastal equilibrium (controlled by head-
land geometry and wave patterns) but have
extremely high erosion potential if this tenuous
equilibrium is disturbed (as it was at Half
Moon Bay, where erosion rates increased to as
much as 2.0 m/yr just south of a breakwater
built in 1959) .

4. Sea-cliff retreat does not proceed in a steady,
continuous manner but rather proceeds inter-
mittently, most ‘material being removed cata-
strophically during heavy storms or during the
winter months when the waves are highest.

5. Landsliding (rotational slumps, debris slides, and
block falls) is a dominant coastal process, es-
pecially where active faults intersect the coast-
line.

6. Marine caves are common along segments of
coastline consisting of the highly jointed Puri-
sima Formation (Pliocene).

7. The San Mateo County coastline is a sand-defi-
cient coastal regime with sandy beaches pro-
viding protection to backshore features only in

 

211

covesand embayments, across the mouths of
drowned valleys, and along the northern sides
of headlands (such as Point Afio Nuevo) where
sand has collected due to southward littoral
drift.

8. No data currently are available on the relative
proportions of beach sand supplied by direct
coastal erosion or stream transport, but stream
transport appears to be the dominant agent.

The data gathered in this study have been incor—
porated into land-use policy by the Central Coast
Regional Commission of the California Coastal Zone
Conservation Commission and have been used by
other Federal, State, and local agencies for numer-
ous land-use problems in the San Mateo County
coastal zone. This local study is intended to serve
as a prototype for future regional studies of coastal
processes.

San Francisco Bay region

The report on coastal geologic processes being pre-
pared as part of the USGS-HUD San Francisco Bay
Region Environmental Study served as a prototype
for making Earth—science data available to the Gen-
tral Coast Regional Commission of the California
Coastal Zone Conservation Commission. Data com-
piled by P. A. McCrory, “J. C. Tinsley 111, H. G.
Greene, and K. R. Lajoie on coastal morphology,
lithology, and sea-cliff erosion rates provided the
basis for establishing three relative coastal stability
categories in San Mateo, Santa Cruz, and Monterey
Counties. Segments of the coastline characterized by
inherently unstable materials such as landslide de-
posits or sand dunes andby historic sea—cliff erosion
rates in excess of 0.3 m/yr were labeled unstable.
Segments characterized by inherently stable material
such as granite and by historic sea-cliff erosion rates
less than 0.1 m/yr were labeled stable. Segments
where historic sea-cliff erosion rates fell between
these values, or where data were not adequate to
establish a precise rate, were labeled moderately
stable. The Central Coast Regional Commission
adopted land-use policies based on the particular
geologic constraints within these three stability cate-
gories. These local policies in turn served as the
model for statewide policies adopted by the State
Commission relating geologic factors and land use
along the coastal bluffs.

Data on other geologic features and processes in
this segment of the coastal zone are being compiled
by Greene, McCrory, and Lajoie in cooperation with
the Central Coast Regional Commission. Seismic haz-

212

ard data are being compiled at a 1 :200,000 scale for
regional planning purposes. Slope stability data are
being compiled at a 1:62,500 scale. Location and
original extent of various coastal environments such
as beaches, dune fields, and estuaries are being com-
piled at 1:200,000 and 1 :62,500 scales. All this in-
formation is used by the Coastal Commission in gen-
eral planning and in evaluating development propos-
als and environmental impact reports.

VOLCANO HAZARDS

Increased hydrothermal activity at Mount Baker, Washington

An increase in the emission of steam was first
noted March 10, 1975, in Sherman Crater at Mount
Baker, and unusually voluminous fumarolic activity
was still continuing in late April, according to D. R.
Crandell (USGS). The crater is breached on the
eastern side and drains into a hydroelectric power
reservoir in the Baker River valley. Studies by J. H.
Hyde (Univ. of Washington) indicated that many
large mudflows of hydrothermally altered rock have
originated at the volcano in postglacial time and
have moved into the Baker River valley. The possible
consequences of another mudflow, as well as the
possibility of a pyroclastic eruption, have led to the
initiation of several types of monitoring. Seismo-
graphs have been installed by University of Wash-
ington geophysicists, and other scientists have ex-
amined the composition of fumarolic gases; USGS
Water Resources Division personnel have been moni-
toring pH and the chemistry of the stream that
drains the crater. According to Stephen Malone
(Univ. of Washington), the seismographs did not
record any earthquakes of unequivocal volcanic
origin during their first few weeks of operation. The
US. Forest Service is considering placing restric-
tions on certain kinds of future visitor use in the
area of the volcano. David Frank (Univ. of Washing-
ton) is compiling and synthesizing all data pertinent
to the current activity as they become available.

Potential volcanic hazards in northern California

Hot pyroclastic flows and lahars of volcanic rock
debris from two eruptive centers repeatedly spread
across the area between the communities of Weed
and Mount Shasta, Calif., during Holocene time.
Studies of the resulting deposits by C. D. Miller and
D. R. Crandell showed that pyroclastic flows and
lahars of nonvesicular rock debris moved westward
from Shastina, a parasitic cone on Mount Shasta
Volcano, about 9,200 yr ago. Similar events recurred

 

GEOLOGICAL SURVEY RESEARCH 1975

between 9,200 and 5,000 yr ago during the formation
of the Black Butte plug dome, which is situated 11
km southwest of Shastina. Pyroclastic flow deposits
of nonvesicular rock debris and pumice formed at
that time extend from north of Black Butte south-
ward beyond Mount Shasta City. Evidence of as
much as 10 m of vertical displacement along east-
trending faults during the interval between two of
the youngest pyroclastic flows from Black Butte sug-
gests that the adjacent area subsided during a late
stage of formation of the plug dome. The eruption
of new plugs or domes on the western or southern
sides of Mount Shasta could result in hot pyroclastic
flows and lahars that might endanger life and prop-
erty in communities near the flanks of the volcano.

Volcano hazards at Lassen Volcanic National Park

Owing to geologic hazards in the Chaos Crags
area on the northern side of Lassen Peak, the Na-
tional Park Service recently closed the Manzanita
Lake visitor facilities in Lassen Volcanic National
Park. However, Lassen Park remains open. Lassen
Peak, the only volcano in the conterminous United
States that has erupted in this century, dominates
the 1127-ka park. A period of activity took place be-
tween 1914 and 1921. The activity appears to have
ceased, and today Lassen Peak is believed to be a
dormant volcano. Other features of the park are
fumaroles, hot springs, and geysers.

The decision to close the visitor facilities was
based on USGS studies made by D. R. Crandell, D. R.
Mullineaux, R. S. Sigafoos, and Meyer Rubin. After
studying the area, the USGS scientists concluded
that rock avalanches could occur without warning in
the highly unstable Chaos Crags area east of Man-
zanita Lake. In a recent neWs release from the Na-
tional Park Service, the situation at Manzanita Lake
was likened to an event that occurred at Hebgen
Lake in Gallatin National Forest near Yellowstone
National Park in 1959, where 28 persons lost their
lives in an earthquake-caused landslide that de-
stroyed a Forest Service campground.

ENVIRONMENTAL PROBLEMS RESULTING
FROM MINING

Surface subsidence over bituminous coal mines, southwestern
Pennsylvania

Kent Bushnell compared overburden, mining, and
other bituminous coal mining factors with the dis-
tribution of recorded damaging surface subsidence
events related to the mining of the Pittsburgh and

GEOLOGY AND HYDROLOGY APPLIED TO THE PUBLIC WELFARE

Upper Free‘port coal beds. His findings suggest that
the time of mining (before or after April 27, 1966)
is more critical to the potential for future damaging
subsidence than other factors. April 27, 1966, was
the effective date of the Pennsylvania law requiring
that coal be left in the ground to support certain
structures and to make the opportunity for similar
protection available to others. The thickness of over-
burden above mined—out areas also is a significant
factor. Areas with certain overburden thicknesses
that were undermined before 1966 have a greater
likelihood of future damaging subsidence than areas
mined after 1966 or mineable in the future. Damag-
ing subsidence has been known to take place more
than 30 yr after cessation of mining. Bushnell’s re—
sults are contained on a 1:125,000-scale map that is
a general classification of land relative to subsidence
potential.

Surface-mine reclamation in the eastern Powder River Basin,

Wyoming

Reclamation of surface-mined lands traditionally
has been considered in terms of reestablishing soils
and vegetation on abandoned spoils. However, in
large areas of the Powder River Basin of northeast—
ern Wyoming and southeastern Montana, strippable
coal deposits are thick in comparison with overbur—
den. The changes in topography, erosion patterns,
and surface- and ground-water systems resulting
from coal extraction likewise are of critical im-
portance in evaluating reclamation potential. In the
Gillette areas along the eastern side of the basin, for
example, surface mining of the Wyodak-Anderson
coal bed will lower the ground surface 15 m or more
in many places as well as create a narrow linear
trough as much as 30 m deep at the high wall. Maps
now in preparation, showing how the landscape may
appear after mining and b-ackfilling and based on
present topography and coal and overburden thick-
nesses, indicate where special planning is required
in the premining stages in order to minimize per-
manent environmental damages and to determine
proper reclamation practices.

INVESTIGATIONS RELATED TO NUCLEAR
ENERGY

UNDERGROUND NUCLEAR EXPLOSIONS

The USGS, through interagency agreements with
ERDA and DOD, investigates the geologic and
hydrologic environments of each site where under-

 

213

ground nuclear explosions are conducted. Most of
these sites are at the Nevada Test Site (NTS).
Geologic and hydrologic data are needed to evaluate
the safety, engineering feasibility, and environ-
mental effects of nuclear explosions.

Hydrologic studies at and near the NTS have
revealed several noteworthy observations in rela-
tion to the nuclear testing program.

W. W. Dudley and G. C. Doty completed a water-
table map of Yucca Flat that incorporates correc-
tions for the effect of head losses at various depths
on composite water levels in observation wells that
penetrate the aquifer.

Detailed hydraulic testing by D. I. Leap of the
carbonate aquifer at an experimental tracer site in
the Amargosa Desert (southwest of the NTS) re—
vealed that the greatest transmissivity is subparallel
to the strike of thrust and Basin and Range normal
faults. Amplitudes and wavelengths of water-level
oscillations are directly related to the size of solu-
tion—enlarged fractures within the carbonate aqui-
fer.

Water moving downward through fractures in
Rainier Mesa at the NTS was shown by H.'C.
Claassen to retain a high percentage of bivalent
cations, whereas water perched in ash-fall tufl’s
changes to predominantly monovalent cations.

Analyses by A. F. White of ground water from
Oasis Valley (west of the NTS near Beatty) showed
that solute compositions are determined principally
by hydrolysis and dissolution of volcanic glass in
the varied lithologic sequence of the Pahute Mesa
(northwestern part of the NTS) ground-water
basin. Increased concentration of the solutes within
the valley indicates that about half of the ground-
water replenishment is consumed from the ground-
water reservoir by evapotranspiration.

Hydrologic conditions at Project Faultless, a
nuclear explosion conducted off the NTS in north-
ern Nye County, Nev., on January 19, 1968, have
been continuously monitored since that date. Water-
level measurements in a drill hole that penetrates
the collapse chimney above the explosion show that
the water level in the chimney had remained stable
at about 518 m below the local water level until it
began to rise in October 1974. According to G. A.
Dinwiddie and D. D. Gonzalez, the water level in
the chimney has risen at the rate of 0.3 m/d dur-
ing October, November, and December of 1974.
Radiochemical analyses show a decrease in tritium
in the water, presumably because of dilution. The
rate of chimney infill is being continuously moni-
tored, and water samples are being collected at bi-

214

monthly intervals in order to effectively document
the change of hydrologic conditions that began in
October 1974.

Permanent offsets in ground-water levels, meas-
ured with respect to preexplosion water levels, oc-
curred as a result of the Rio Blanco nuclear explo-
sion of May 17, 1973, in the Piceance Creek basin
in Colorado. The offsets are as much as —5.2 m in
the upper aquifer, +1.5 m in the lower aquifer,
and 0.15 m in the Douglas aquifer. According to
J. E. Weir, Jr., and Gonzalez, these offsets prob-
ably are the result of changes in the effective porros-
ity of the respective aquifers and were observed as
far as 29 km from ground zero. Analyses of hydro-
graphsof wells in the vicinity of the Rio Blanco
site imply an associated increase in permeability in
some parts of the basin. the result being more ef—
fective recharge from snowmelt.

Hydraulic fracturing of the gas-bearing formation
at the Rio Blanco site conducted in October 1974
did not produce any observable effects on ground-
water levels measured in the same wells measured
during the Rio Blanco nuclear explosion.

On Amchitka Island in Alaska, W. C. Ballance,
Gonzalez, and William Thordarson collected water
samples from streams and lakes near the site of
the Cannikin nuclear explosion. These samples were
analyzed for tritium, gross alpha, and gross beta/
gamma content. No appreciable differences were
found between these data and the data obtained from
water samples collected prior to the Cannikin event.

Investigations into the geomechanical charac-
teristics of the geologic medium are used in site
evaluation and development at the NTS. These in-
vestigations, conducted primarily in the tunnels
under Rainier Mesa, have spawned the development
of new instrumentation and techniques, as well as
studies to evaluate and improve existing technology.

An air-injection technique to study fracturing
around a tunnel in volcanic rocks was developed by
C. H. Miller, D. R. Cunningham, and M. J. Cunning-
ham. The method uses a permeameter apparatus to
indicate the intensity and depth of natural, stress-
induced, and blast-induced fractures around under-
ground openings. Although to date this technique
has been used only in the volcanic tuffs of Rainier
Mesa, it can be applied in other rock types where
permeability is confined to fractures.

The evaluation of in-place rock stress in Rainier
Mesa has taken on increased importance in the last
few days. Rock stress information is used in the
engineering design of underground excavations and

 

GEOLOGICAL SURVEY RESEARCH 1975

in the containment evaluation for underground
nuclear explosions. USGS efforts are directed to-
ward the determination of in-place stress and the
examination and evaluation of various stress deter-
mination methods.

The primary method of stress determination in
Rainier Mesa is the US. Bureau of Mines overcore
technique. This method has been well developed
and is considered to give reliable results. Stress de-
terminations made by this method are used as the
standard against which the stress determinations
of other methods are compared.

Miller and G. R. Terry experimented with the
hydrofracture method of stress determination in
the tunnels of Rainier Mesa. Several fracturing
experiments using colored water'were conducted in
horizontal and vertical holes. Some of the holes
were then mined out, and the induced fractures ex-
amined and mapped. Whenever possible, the hydro-
fracture stress measurements were compared With
stress measurements obtained by the overcore
method. In some cases, stress measurements ob-
tained by the hydrofracture method provided good
data, whereas, in other instances, the results were
questionable. Work is continuing, with emphasis on
improving hydrofracture techniques and equip-
ment.

R. D. Carroll and M. J. Cunningham made exten-
sive crosshole, uphole, refraction seismic, and sonic
velocity measurements in the tuffs on Rainier Mesa.
These measurements revealed a horizontal velocity
anisotropy of nearly 2:1; the direction of lower
velocity is at right angles to the direction of fault-
ing in the area.

RELATION OF RADIOACTIVE WASTES TO THE
HYDROLOGIC ENVIRONMENT

Development of nuclear-energy facilities has re-
sulted in nuclear wastes in gases, liquids, and solids.
These wastes must be isolated from the hydrologic
environment for varying periods of time, depend-
ing upon the radioactive half-life of the waste prod-
ucts. USGS research, sponsored by ERDA, has been
directed toward methods of disposing of these
waste products and understanding geohydrological
processes and principles of waste movement from
storage and disposal sites.

Mobility of buried radioactive wastes

A study was made to evaluate the geohydrologic
and geochemical controls on the possible subsurface
migration of radionuclides from a radioactive solid-

GEOLOGY AND HYDROLOGY APPLIED TO THE PUBLIC WELFARE

waste burial ground. The Idaho National Engineer-
ing Laboratory burial ground is located in eastern
Idaho above the Snake River Plain aquifer. The
subsurface strata (are basalt and interbedded sedi-
ments. According to J. T. Barraclough, J. B. Robert-
son, and V. J. J anzer, some waste products have ap-
parently been carried by percolating precipitation
and runoff water from the surface burial sites to a
sediment bed about 34 m deep. However, owing to
statistical error and some possibilities of sample
contamination, conclusive proof of the apparent
migration is lacking. Therefore, additional subsur-
face sampling appears to be warranted.

Numerical model of subsurface nuclear-waste percolation

A quasi—three—dimensional numerical model was
developed by J. B. Robertson to simulate the mi-
gration of aqueous radioactive wastes from disposal
seepage ponds at the Idaho National Engineering
Laboratory. In the model, finite-difference tech-
niques are used to solve equations of water flow and
solute transport for a perched ground-water system
with vertical leakage through the bottom. The model
adequately simulates“ observed field data from the
real field system and Will be used to help analyze
present and future subsurface distribution of waste
isotopes such as 90Sr. The system incorporates hori-
zontal and vertical flow, nonhomogeneous media,
effects of radioactive decay, ion exchange, and hy-
draulic dispersion. The model indicates that no de-
tectable concentration of 90Sr will percolate into the
Snake River Plain aquifer, 137 m below the ponds,
within the next 25 yr.

Burial-ground monitoring at Oak Ridge National Laboratory

Solid wastes contaminated by radioactive sub-
stances are usually buried to remove the potentially
hazardous materials from man’s environment. All
though contaminants may be leached from the
waste, burials are made on the assumption that
leached nuclides will be retained in the geologic en-
vironment by sorption or ion exchange and thus
restrained from pathways leading back to man.

At Oak Ridge National Laboratory in Tennessee,
an estimated 170,000 m3 of waste have been in-
terred in six burial grounds. D. A. Webster re-
ported that the monitoring system is adequate for
quantifying contaminants contained in surface
water released to the Clinch River but is inadequate
for defining contaminant origin and for monitoring
the transport of contaminants in ground water
from the burial grounds to the surface drainage.

 

215

Disposal of radioactive wastes in shale

Low- and intermediate-level liquid radioactive
wastes (specific activity less than 0.53 Ci/l) were
mixed with cement and clay and injected by hy-
draulic fracturing into a dense, nearly impervious
shale formation with nearly horizontal bedding.
The injected wastes were thereby immobilized and
contained within a thin zone of the shale, where
they were isolated from the biosphere. This tech-
nique was used to ascertain whether bedding-plane
fractures can be induced hydraulically in shale and
Whether the orientation of the induced fractures
can be determined by a reliable and economical
method. '

Results of research projects conducted at West
Valley, N.Y., and Oak Ridge, Tenn., proved that
bedding—plane fractures can be‘induced and propa-
gated hydraulically in shale, at least at a shallow
depth (600 m). R. J. Sun (1969) developed a mathe-
matical model to describe the relationship between
the uplift of the ground surface and the induced
horizontal fractures. Sun (1973: Sun: and C. E.
Mongan, 1974) demonstrated that the orientation
of induced fractures can be predicted by injection
pressure and pressure decay. The predicted results
can be verified by gamma-ray survey-s made in ob-
servation wells located within a radial distance of
60 to 100 m from the injection well if the injected
fluid is tagged with gamma-activity isotopes.

A hydraulic fracturing site for disposal of radio-
active wastes at the Holifield National Laboratory
(formerly the Oak Ridge National Laboratory) was
evaluated by the methods developed during the re-
search projects.

Borehole gamma spectrometry used to locate radioisotopes

T. A. Taylor and W. S. Keys, using borehole
gamma spectrometry, were able to locate and iden-
tify artificial radioisotopes in a cased well adjacent
to the Maxey Flats radioactive-waste burial ground
in Kentucky. The investigators were able to iden-
tify GOCo, 134Ce, and 137Ce behind the casing in test
hole 12E. By using energy discrimination through
threshold detectors, they were able to make a con-
tinuous gamma log that responded mainly to the
two cesium isotopes and to make another gamma
log that responded mainly to 6"Co.

Two spectral probes (with outside diameters of
4.76 and 10.16 cm) have been developed and suc-
cessfully tested; their present depth limitation of
1,800.m and temperature limitation of approxi-
mately 65°C can be extended by modifications of the
probes.

216

Waste management, Paradox Basin, Utah

The salt-bearing Middle Pennsylvanian Paradox
Member of the Hermosa Formation is diapiric in
nature and has a thickness of at least 3,400 m in
the core of the northwestern end of the Salt Valley
anticline in Grand County, Utah, according to
R. J. Hite and S. W. Lehman (1973). The Paradox is
characterized by a sequence of salt units alternating
With units of anhydrite, dolomite, and black shale.
Because the Paradox beds have flowed from adja-
cent synclines into the anticline, the internal struc-
ture of the saltabearing rocks is complex. In the
collapsed and breached axis of the anticline, the top
of the salt rises to within 200 to 250 m of the sur-
face beneath a caprock of insoluble residuum that
has resulted from the removal of salt by solution.

Results of field studies by L. M. Gard, Jr., and
R. P. Snyder showed that the oldest post-Pennsyl-
vanian rocks exposed in blocks foundered in the
caprock are the upper part of the Brushy Basin
Shale Member of the Jurassic Morrison Formation
overlain by the Burro Canyon Formation, the Da-
kota Sandstone, and the Mancos Shale of Cretace—
ous age. These foundered blocks of Mesozoic rocks
are folded and faulted far less intensely than the
contorted sandstone, limestone, and shale beds of
the Paradox Member.

Waste emplacement in bedded salt

C. L. Jones, L. M. Gard, Jr., A. L. Brokaw, and
G. O. Bachman completed field studies to determine

the geologic and hydrologic conditions in a part Of ‘ highest well—developed buried soil has been collected

southeastern New Mexico that is being considered
as a possible site for emplacement of nuclear wastes
in the bedded salt of the Salado Formation. Two
exploratory boreholes (923 and 1,194 m deep) were
drilled to investigate the hydrogeologic framework
and obtain samples for mineralogical, chemical, and
other studies. Hydraulic tests indicated that the
rocks above the Salado are not saturated with
ground water and have a very low transmissivity.
Other factors favorable to the area include ( 1) very
high geologic stability ranging over 225><106 yr,
(2) probable protection from exhumation by ero—
sion and from invasion by meteoric ground water
for several hundred thousand years, and (3) avail-
ability of remote public lands with thick (>500 m)
salt deposits.

 

GEOLOGICAL SURVEY RESEARCH 1975

SITES FOR NUCLEAR-POWER REACTORS AND
OTHER FACILITIES

Reactor-site investigations

Twenty—two reactor sites in various states and
Puerto Rico were reviewed and evaluated at the re-
quest of the Nuclear Regulatory Commission (for-
merly the Atomic Energy Commission) during the
past year by R. H. Morris and other members of the
Reactor Site Investigations Project. The purpose of
these investigations was to allow engineering design
criteria for nuclear facilities to be chosen on the
basis of thorough local and regional geologic data
collected by an applicant who wishes to build a nu-
clear-power reactor.

Site seismicity

Seismic evaluations submitted by applicants con-
sider the seismic history of a reactor site and its
relation to the tectonic framework of the area. At
the request of the Nuclear Regulatory Commission,
S. R. Brockman and J. F. Devine reviewed the evalu-
ations of sites in areas of differing seismicity and
when necessary appeared as expert witnesses at
hearings.

Quaternary dating techniques

Loess stratigraphy in southern Idaho, near the
National Reactor Testing Station, shows several
buried soils more developed than the surface soil.
K. L. Pierce defined four episodes of loess deposition,
each followed by a soil—forming interval. Material
from a thin volcanic ash in the loess beneath the

for fission-track dating. Superhydration age esti-
mates by V. C. Steen-Mclntyre indicated that the ash
is much older than 7,000-yr-old ash and significantly
younger than 600,000-yr—old ash; the ash is probably
about 100,000 yr old.

F LOODS

Three major phases of USGS flood studies are ( 1)
measurement of stage and discharge, (2) definition

' of the relation between the magnitude of floods and

their frequency of occurrence, and (3) delineation of
the extent of inundation of flood plains by specific
floods or by floods having 'specific recurrence
intervals.

GEOLOGY AND HYDROLOGY APPLIED TO THE PUBLIC WELFARE

OUTSTANDING FLOODS

Hydrologic assessment of a flash flood in Eldorado Canyon,

Nevada

A devastating flash flood of thundershower origin
struck Eldorado Canyon, a 9-km2 drainage area in
southern Nevada, at about 2:30 p.m., September 14,
1974. The flood killed at least 9 people, destroyed 5
trailer homes and damaged many others, obliterated
a restaurant, and destroyed 38 vehicles, 19 boat trail-
ers, 23 boats, half of the boat-docking facilities, and
the gas dock. The severe runoff resulted fro-m intense
basinwide rain and hail at rates of up to 76 mm of
precipitation per half hour. The storm moved down-
basin and generally increased in intensity with time,
this increase compounding the runoff rates. In a
report by P. A. Glancy and Lynn Harmsen (1975),
peak discharge was estimated to be 2,150 m3/s just
upstream from the developed area near the canyon
terminus. Runoff deposited an estimated 53,500 m3
(about 91,000 metric tonnes) of inorganic sediment
in Lake Mohave and throughout the downstream can-
yon reach. It also delivered an estimated 4,930 m3 of
organic or floating debris to Lake Mohave as well as
about 2,500,000 m3 of water. The inorganic sediment
was estimated to consist of less than 1 percent boul-
ders, 40 to 60 percent gravel, 20 to 40 percent sand,
and 10 to 25 percent silt clay. The recurrence inter-
val for runoff of this magnitude is great, but a simi-
lar event could occur in any given year. Although it
is common in the desert Southwest, this type of hy—
drologic event is not fully understood and is frequent-
ly ignored; thus, the danger to developed areas is
ever present. With proper understanding and plan-
ning, the risk of damage from similar floods in the
future may be greatly reduced.

Flooding on St. Croix and St. Thomas, V.|.

Extensive flooding on St. Thomas and St. Croix,
V.I., resulted from heavy rains on November 12,
1974; as much as 102 mm of rain fell in a 4-h period.
Estimated damage exceeded $1 million on St. Croix
and also on St. Thomas. W. J. Haire and K. G. John-
son reported that flood magnitudes approached those
of the May 1960 flood. The extent of flooding was
delineated on topographic maps (scale 1:4,800) ; flood
profiles were obtained for about 24 km of channel.

FLOOD-FREQUENCY STUDIES

Flood-frequency analyses of California streams

S. E. Rantz and J. R. Crippen (1975) developed a
method for estimating the long-term value of the

 

217

logarithmic skew coefficient for use with the log-
Pearson type III distribution in computing the flood-
frequency curve for a gaged site. They developed
regional equations that relate the logarithmic skew
coefficient to logarithmic transformations of (1)
mean annual basinwide precipitation and (2) mean
annual peak discharge per square kilometre. The
technique seems to be satisfactory for use in the
greater part of California where, over large areas,
the peak discharge in any year is usually associated
with a single widespread general storm—or with a
series of such storms where snowmelt runoff is in-
volved—rather than with localized precipitation
events.

Flood-flow studies in Connecticut

L. A. Weiss analyzed the magnitude and frequency
of annual maximum peak streamflows for the period
of record at 105 stream—gaging stations and the
magnitude and frequency of the annual maximum
rainfall for storm durations of 1, 4, 6, 12, and 24 h.
Historical data at long-term stream-gaging sites
were used to compute skew coefficients; these in turn
were used to relate magnitude to frequency. Long-
term skew and standard deviation were plotted on
isopleth maps and were then used to compute skew
and standard deviation at short-term sites. Ratios
between long-term mean and short-term mean for
long-term sites were applied to short-term sites to
make them comparable to the long-term sites.

A regression analysis of the 2- and 100-yr floods
for nonurbanized sites was found to be related to
parameters such as drainage area, main-channel
length divided by the square root of main-channel
slope, and rainfall duration and frequency.

The standard error of estimate for nonurbanized
streams with drainage areas ranging from 2.6 to 26
km? was :35 percent for the 2-yr flood and :48 per-
cent for the 100-yr flood. The standard error for
streams with drainage areas larger than 26 km2 was
:27 percent for the 2-yr flood and :35 percent for
the 100-yr flood. For eight urbanized streams in the
Connecticut River basin in the State of Connecticut,
the ratio of the computed to the actual 2- and 100-yr
floods was found to be related to the percentage of
the drainage area that is storm sewered. For 100-
percent sewering, the ratio of the urbanized to non-
urbanized 2-yr flood was 3:1, and for the 100—yr flood
it was 2:1.

Flood profiles of the Alafia River in west-central Florida

The Alafia River basin in west—central Florida
drains about 109,000 ha of land that is undergoing

218

rapid urban development. Some residential develop-
ments are on the flood plain of the river, which dis-
charges into East Tampa Bay. A. F. Robertson re-
ported that recurrence intervals of seven different
floods and flood elevation profiles have’been’ deter-
mined for 67 km‘ of the river and its two principal
tributaries.

Depth and frequency of floods in Illinois

B. J. Prugh, Jr., developed multiple-regression
equations for predicting the 2-, 5-, 10-, 25-, 50-, and
100-yr flood depths from data collected from 177
gaging stations in Illinois. Relationships based on
area, slope, and 2- and 100-yr flood discharges were
studied. The 2-yr flood discharge was selected as the
best variable to predict the various frequencies of
flood depths. The final equations had standard errors
of estimate that varied from 31 percent for the 2—yr
flood depth to 23 percent for the 100-yr flood depth.
The equations will be useful for advanced planning
and preliminary flood-plain evaluations but are not
designed to replace detailed hydrologic studies.

Duration and frequency of high flows on Iowa streams

A report by O. G. Lara (1974), which contains sta-
tistical data on flood volumes for 97 recording gaging
stations in Iowa, has been published. Data included
in tables, are the magnitude and the frequency of
occurrence of maximum annual average flows and
the corresponding volumes for selected periods rang-
ing from 1 to 183 consecutive days. The tables also
include the water-surface elevations corresponding
to‘the listed elevations.

Estimating peak discharges in Massachusetts

G. D. Tasker (C. G. Johnson and Tasker, 1974a)
compared a modification of the Potter method (W. D.
Potter, 1957) with another multiple-regression tech;
nique to predict the 10- and 50-yr peak discharges at
77 gaging stations in Massachusetts. The predicted
peak discharges made by each method were compared
with the peak discharges estimated from station fre-
quency curves. Results indicate that, although the
random error for both methods is about the same, the
modified Potter method systematically predicts peaks
that are higher (150 percent) than those estimated
from station frequency curves.

Flood-frequency studies in Minnesota

A multiple-regression analysis of all gaging-station
records in Minnesota is underway to derive equations
that will provide flow estimates for various frequen-
cies of floods. L. C. Guetzkow reported that initial

 

GEOLOGICAL SURVEY RESEARCH 1975

analyses of station frequency curves indicate that the
results of the log-Pearson type III method are unac-
ceptable. Computation of a log-Pearson distribution
using an assigned regional value for the skewness of
the logarithms has been adapted to derive data
values for the regression analysis that are based on
the study of individual gaging-station frequency
relations.

Flood-frequency study on small streams in Missouri

L. D. Hauth (1974) reported that the USGS rain-
fall-runoff model was used in Missouri to provide
small-stream peak-flow data in a statewide flood-
frequency study. Regional skew coefficients defined
by'C. H. Hardison (1974) were used in large-drain-
age-area station frequency curves developed by the
log-Pearson type III distribution.

The definition of estimating equations based upon
combined large- and small-stream data indicated that
the assumption of a linear relation between the loga-
rithms of the variables was inadequate. Alternative
curvilinear models and variable transformations
were tested, and the most satisfactory model found
was in the form Q: b1Ab2A’MS’“, where A is the basin
size and S is the main-channel slope. Constants in
the logarithmic transformation, log Q=log b1
+b2Ab“ log A+bl log S, could not be evaluated di-
rectly by linear multiple regression; however, re-
peated trial and error solution indicated that when
b3= —0.02, multiple-regression analysis to deter-
mine the remaining constants provided relations
having the minimum standard error of estimate.

Estimating magnitude and frequency of floods in North Carolina

N. M. Jackson, Jr., conducted a study to develop
equations for estimating the magnitude and fre—
quency of floods on ungaged natural streams in
North Carolina. The step-backward multiple-regres-
sion technique relating flood peaks to basin and cli-
matic characteristics was used. Preliminary results
‘indicate that two sets of equations, one for the Coast-
al Plain and one for the mountains and the Piedmont
province, are necessary.

Small-area flood-frequency study in North Dakota

Flood data from 126 sites have been analyzed by
regression analysis to provide relations for estimat-
ing the magnitude of floods in small basins in North
Dakota. Equations were developed by O. A. Crosby
for the 10-, 25-, and 50-yr floods. The State was di-
vided into three regions to improve the estimating
relationships: The parameters found significant in de-
fining these relationships were drainage area, stream

GEOLOGY AND HYDROLOGY APPLIED TO THE PUBLIC WELFARE

density, soil-infiltration index, and evaporation. The
standard errors of estimate for the regression equa-
tions ranged from —53 to +115 percent. The rela-
tions developed can be used for any site in North
Dakota in a drainage area ranging from 0.2 to 260
km2 where the flood flow is unregulated.

Floods from small drainage areas in New Mexico

A. G. Scott (1974) reported that a trial extension
of the record of annual flood peaks for one station in
New Mexico was made by utilizing a rainfall-runoff
hydrograph simulation model. A comparison of the
frequency curves of annual peaks for recorded and
simulated data indicates that results of the simula-
tion are reasonable.

Flood-frequency relations in Pennsylvania

Regression models relating floods with recurrence
intervals of 2.33, 10, 25, 50, and 100 yr to drainage
basin characteristics were completed for eight de-
fined flood regions that cover Pennsylvania. H. N.
Flippo, Jr., reported standard errors of estimate in
the range of 9 to 37 percent for those models applica-
ble to drainage basins larger than 39 kmz. The high-
est standard error of estimate for those models ap-
plicable to drainage areas from 5 to 39 km2 is 56
percent.

Small-area flood hydrology of Massachusetts and Vermont

C. G. Johnson and G. D. Tasker (1974a, b) devel-
oped a technique for estimating the magnitude and
frequency of floods on streams in Massachusetts with
drainage areas between 0.65 and 1,290 km2 and on
streams in Vermont with drainage areas between
0.70 and-2,700 km-. Multiple- regression techniques
using basin characteristics and data collected at a
network of gaging stations defined the relation be-
tween flood peaks. Results show that flood peaks can
be estimated from knowledge of a basin’s drainage
area, its average seasonal snowfall, the area of its
lakes and ponds, and its maximum 24—h rainfall hav-
ing a recurrence interval of 2 yr.

FLOOD MAPPING

Flood-hazard study—IOO-yr flood stage for Apple Valley Dry
Lake, California

A study of the flood hydrology of Apple Valley,
Calif., was undertaken by M. W. Busby to determine
the 100-yr flood stage for Apple Valley Dry Lake.
Synthetic hydrologic techniques were used because
no adequate hydrologic or meteorologic data for the
basin were available. The ‘100-yr flood-zone stage

 

219

was estimated to be at an elevation of 886.82 m above
mean sea level.

Flood maps of Cypress Creek, Florida

W. R. Murphy, Jr., developed flood profiles of the
2-, 5-, 10-, 25-, 50-, and 100-yr flood-peak discharges
for the lower reach of Cypress Creek under existing
hydrologic conditions. The study area includes a
stream reach that may become a flood-detention area.

Flood-prone areas in Minnesota

L. C. Guetzkow reported that studies are being
conducted on designated reaches of streams and iso-
lated communities (Guetzkow, 1971, 1972a, b; G. H.
Carlson, 1971a, b, 1972; Guetzkow and Carlson, 1974;
K. T. Gunard, 1972; C. W. Saboe, 1973) to provide
information required by Minnesota State regulations
to implement comprehensive flood-plain management
programs for flood—prone areas. Priorities for the
selection of study areas are based on the degree of
flood—damage potential and development pressures.
The reports contain flood- frequency analyses, flood
profiles, flood~inundation maps, and floodway evalua-
tions. These data have contributed significantly to
making the public aware of potential flood dangers
and have provided community officials with the in—
formation necessary for adoption of land-use control
measures.

Flood-insurance studies in Puerto Rico

Investigations were conducted by W. J. Haire to
identify flood-hazard areas and to provide the flood
profiles and flood-elevation frequency data that are
used to establish the actuarial rate structure for
flood insurance. The data are also used to evaluate
land-use control measures that local governmental
units must adopt to maintain eligibility for Federal
flood insurance.

Flood-prone areas in Puerto Rico

Flood discharges on the Rio Tallabo-a, Rio Coamo,
Rio Utuado, Rio Guadiana, and Rio Jayuya with re-
currence intervals of 50 and 100 yr were determined
by regional analyses. W. J. Haire and K. G. Johnson,
using step-backwater techniques to define flood pro-
files, delineated areas subject to flooding. The data
are used to evaluate required land-use control meas-
ures for local government agencies.

Hypothetical earthquake-caused floods in Jackson Hole,
Wyoming
At the request of the National Park Service, the
USGS prepared a flood map for the Snake River
from Jackson Lake dam to a point 61 km down-

220

stream. Hypothetical floods were routed downstream
for three cases: (1) Instantaneous destruction of the
outlet structure, (2) instantaneous destruction of the
entire dam, and (3) waves overtopping the dam. As—
suming worst case antecedent conditions, W. R.
Glass, J. G. Rank], and T. N. Keefer utilized an ac-
celerated discharge due to the travel of a negative
wave through the reservoir and Muskingum storage—
routing techniques to develop outflow hydrographs
for the first two cases of dam failure. For the case of
wave overtopping, a 3-m wave was assumed to be
propagated from the upstream end of the reservoir.
A multiple-linearization flow-routing model was cali-
brated with streamflow records and modified to han-
dle supercritical flow. Peak discharge rates calculated
as outflow from Jackson Lake were 5,340, 13,740, and
990 mg/s, respectively, for the three cases; modeled
results indicated that these peaks had attenuated 48
km downstream to 5,220 and 12,710 m3/s for the
first two cases. The rate of tributary inflow used in
the computation was 330 m3/s.

Maps of flood—prone areas

Areas inundated by the 100-yr flood are outlined
on topographic maps as part of the National Program
for Managing Flood Losses. The objective of this
program is to quickly inform cities and towns of the
general extent of their potential flood problems.
About 12,000 such maps have been completed for all
of the States, the District of Columbia, and Puerto
Rico.

The program has progressed in two phases. The
first phase, which began in 1969, was directed toward
defining flood limits in populated areas where sig-
nificant flood problems were known and flood infor-
mation was urgently needed. The second phase, im-
plemented during 1972, expanded the areal coverage
to include areas in which future development was
envisioned.

lnundation maps of urban areas

Maps showing areas inundated by major floods,
flood profiles, discharge-frequency relations, and
stage-frequency relations were published during the
year as Hydrologic Investigation Atlases for the fol-
lowing areas: Waiahole-Waikane, Oahu, Hawaii
(C. J. Ewart and Reuben Lee, 1975); Saunders to
Man, W. Va. (G. S. Runner, 1974) ; and Ipswich River
(L. A. Swallow and D. J. Fogarty, 1974) and Nepon-
set River, Mass. (L. A. Swallow and G. K. Wood,
1974).

 

GEOLOGICAL SURVEY RESEARCH 1975

WATER QUALITY AND CONTAMINATION

Arsenic and mercury in proposed reservoir environment

R. F. Middelburg, Jr., reported that two toxic
trace elements, arsenic and mercury, are known to
be present in an area that will form part of a new
reservoir, Lake Sonoma, in Sonoma County, Calif.
The problem primarily centers around a small tribu-
tary, Little Warm Springs Creek, which will be
flooded by the proposed reservoir. Located on a
200-m section of the creek are three geothermal
hot springs known as Skaggs Springs, numerous
geothermal seeps, and an abandoned quicksilver
mine.

Arsenic has been detected in the outflow of the
springs, and realgar crystals (AsS) can be found
in outcrops within the area. Very little mercury
has been detected in the waters emanating from the
area, but it can be detected in elevated concentra-
tions in sediments and biota.

Asbestos was thought to be a potential hazard,
but it has not been detected in any of the water
samples. Boron concentration levels may be high
enough to affect boron-sensitive plants such as
grapes, Which are grown extensively in the valley
below the proposed reservoir.

Monitoring areal and temporal water-quality variation in the San

Lorenzo River basin, California

The San Lorenzo River basin is experiencing
rapid urbanization, and, as a result, heavy demands
are being made on the water resources and waste-
water disposal capabilities of the basin. Water-
quality data from previous studies have not been
adequate to define baseline conditions or to assess
sources of degradation.

In order to determine areal and temporal varia-
tions and problem reaches in the basin, a monitor-
ing system of 15 stations was established. The gen-
eral scheme was to locate one station upstream from
a community and one station downstream to assess
possible contamination from community septic
tanks. Samples were collected monthly.

Although the routine monitoring provided in-
formation on monthly and seasonal variations in
water quality, shorter period effects were not detect-
able. Therefore, an intensive diel survey was made.

Preliminary results after 6 mo of sampling indi-
cate similar water quality among stations. Water
quality is generally Within State standards. No sig-
nificant diel variations have been noticed. Temporal
water—quality degradation corresponds to periods of
high flow caused by rainfall runoff.

GEOLOGY AND HYDROLOGY APPLIED TO THE PUBLIC WELFARE

Contamination of ground water by seleniferous sediments

Water from certain domestic wells in the vicinity
of Golden, 0010., contains selenium in concentra-
tions as high as 450 ,ug/l——45 times the maximum
level set by the USPHS for drinking water. The
selenium is dissolved from organic-rich Cretaceous
sediments of the Arapahoe Formation. R. E. Moran
reported that such high selenium concentrations are
areally discontinuous in the ground water and are
associated with high gross alpha activities (80 to
160 lug/l as natural uranium) and high sulfate
(300 to 1,500 mg/l), nitrate (7 to 22 mg/l as nitro—
gen), and strontium (1,700 to 9,400 pg/l) concen-
trations.

Saltwater intrusion through corroded well casings

Results of an investigation conducted by D. H.
Boggess indicated that saltwater intrusion has oc-
curred in the upper Hawthorn aquifer at several
places in the Cape Coral area in Florida. Chloride
concentrations in water from the aquifer, which
normally range between 100 and 200 mg/l, have
increased to a maximum of 9,500 mg/l in one area.
The source of the intruding saltwater has been iden-
tified as the water-table aquifer, which in some
places contains water with chloride concentrations
of 27,000 mg/l. The intrusion occurs as a result of
corrosion of metal well casings in individual wells,
which permits downward leakage of saltwater into
the upper Hawthorn aquifer.

Rural runoff

The loads of nitrogen, phosphorus, organic car—
bon, dissolved solids, pesticides, and trace metals
entering a rural canal in southern Florida in runoff
were studied by B. G. Waller. Criteria were to be
established for the acceptable loads of nitrogen and
phosphorus that may enter this canal in runoff from
rapidly expanding urban developments. The waters
within the canal are backpumped into Conservation
Area 3 for storage purposes and drainage of this
subbasin. The maintenance of high-quality water
Within the South New River canal and the adjacent
conservation area is dependent on preventing con-
taminated runoff from entering the canal.

Contaminants in Broward County, Florida, controlled canal
system
Quarterly samplings for nutrients and bacterio-
logical paranieters and did studies of dissolved
oxygen, pH, and alkalinity in the Broward County
controlled canal system showed a slight decrease in
contaminants caused by man’s activities, according

 

221

to H. W. Bearden and C. B. Sherwood, Jr. These
changes may be the result of local agencies’ efforts
to reduce the amount of treated sewage effluent en-
tering the canal system.

Coliform contamination of Floridan aquifer well

Analyses of water samples collected from three
isolated sections of the Floridan aquifer in north
Tampa (Temple Terrace) by J. W. Stewart, C. L.
Goetz, and L. R. Mills showed that the upper sec-
tion (30 to 36 m below land surface) had a higher
color reading, more dissolved iron, and a higher
concentration of coliform bacteria than the other
sections tested. Fecal streptococci Were found only
in the middle section (37 to 40 m below land surface).
The bottom section (40 to 47 m below land surface)
had the lowest concentration of iron and coliform
bacteria.

Domestic water supplies contaminated in Hillsborough County,

Florida

Chemical and biological analyses of water sam—
ples collected in an area where a sinkhole occurs
in a lake in the southwestern part of Hillsborough
County, Fla., indicate that the sinkhole is intercon-
nected with several domestic water-supply wells
that are developed in the limestone aquifer. Ac-
cording to A. D. Duerr and C. L. Goetz, living
copepods, typical of those in lake-bottom habitats,
were recovered from two wells. Color units near
the lake sink and two wells were recorded as 225,
120, and 150, respectively; tannin and lignin values
were 2.5, 1.8, and 2.0 mg/l, respectively, and total
organic carbon was 16, 13, and 14 mg/l, respec-
tively.

Sewage effluent disposal by spray irrigation

Since 1966, the city of Tallahassee, Fla, has been
experimentally disposing of up to 5,700 m3/d of
secondary treated sewage effluent by spray irriga-
tion. Effluent has been sprayed on a sandy soil
with a variety of crop cover: undisturbed forest,
rye, ryegrass, pearl millet, kenaf, sorghum-sud—
angrass, Argentine behiagrass, and corn. Bedrock
is generally 9 to 15 m below land surface. Ground-
water levels in the area are generally coincident
with bedrock.

In some respects, the quality of the sprayed efllu-
ent was improved by filtration through the soil and
rock materials. L. J. Slack (1974) reported that
BOD was reduced to less than 5 mg/l, fecal coli-
form bacteria were removed, almost total phos-
phorus removal was achieved, and from 31- to 100-
percent denitrification took place in irrigation fields

222

that received from 50 to 200 mm of effluent per
week.

High-rate efl‘luent application of 350 mm/week
onto 7.3 ha of undisturbed forest resulted in in-
creased chloride and nitrogen to depths of at least
82 m and extending laterally about 550 m. Natural
chloride and nitrate-nitrogen concentrations in this
freshwater aquifer are 2 and 0.05 mg/l, respectively.
Chloride and nitrate-nitrogen concentrations ranged
from 14 to 51 and from 3.7 to 32 mg/l, respective-
ly, for samples collected from depths of 13 to 82
m at a well downgradient of the heavily sprayed
area.

Landfill contaminants in eastern Pinellas County, Florida

Mario Fernandez, Jr., reported that contaminants
from a sanitary landfill site in eastern Pinellas
County, Fla, are moving away from the site
through the shallow sand aquifer. However, pre-
liminary findings at a nearby sludge-disposal opera-
tion, which began in November 1974, indicate that
leachate from the sprayed sludge is being retained
Within the disposal area.

Underground disposal of liquid industrial wastes

Since 1963, more than 38 million cubic metres of
acidic industrial waste has been injected under
high pressure into a confined saline-water-filled
limestone aquifer of low transmissivity between 430
and 520 m below land surface near Pensacola, Fla.
G. L. Faulkner and C. A. Pascale (1975) reported
that, by 1975, injection rates averaged about -145
l/s. Wellhead pressures at the two injection wells
averaged 12 kg/cm2 (1,177 kPa). The pressure at
two deep monitor wells in the injection zone 3.1
km north and 2.4 km south of the injection site
averaged 7.9 kg/cm2 *(775‘kPa). At the injection
site, pressure in a shallow monitor well in the
aquifer immediately above the 67-m-thick confining
layer averaged about 2.1 kg/cm2 (206 kPa) and
continued to decline slightly.

A regional monitoring program revealed that, by
mid-1974, the waste body occupied an area of slight-
ly more than 18 km2 in the upper approximately 15
m of the injection zone. There are no indications
that waste has leaked upward through the 67-m-
thick confining layer or that pressure increases in
the injection zone have had any effect on pressure
in the aquifer above the confining layer. By mid—
1974, pressure in the injection zone at the injection
site had increased eightfold since injection began,
and it is calculated that pressure effects in the in-

 

GEOLOGICAL SURVEY RESEARCH 1975

jection zone extended over an area of more than
13,000 kmz.

Increases in alkalinity and dissolved organic car-
bon concentration at the southern monitor well, a
noticeable increase in gas content, and a distinctive
odor of injected waste indicated the arrival of dilute
waste at the southern monitor well in mid—1973;
organic analyses of the well water also showed that
a dilute form of the organic waste had reached the
well. The gases methane, nitrogen, carbon dioxide,
argon, and helium were detected in both deep moni-
tor wells. The amount of methane in gas samples
from the southern monitor well was 11/2 times
higher (79.5 percent by volume) than that in sam-
ples from the northern monitor well.

Sulfate-chloride ratio decrease indicates waste migration

M. I. Kaufman and D. J. McKenzie (1975) found
that geochemical data from an industrial deep—well
waste injection system southeast of Lake Okee-
chobee, Fla., indicate a decrease in sulfate con-
centration concomitant with an increase in hydro-
gen-sulfide concentration, which is a result of the
oxidation of injected organic waste by anaerobic
bacteria. Subtle decreases in the sulfate-chloride
ratio suggest that the waste migrated upward to a
shallow monitor well about 27 mo after waste in-
jection began and again within 15 mo of the re-
sumption of waste injection after the injection well
was deepened. The possibility of a hydraulic con-
nection between the injection zone and the overly-
ing monitoring zone is implied. The decrease in the
sulfate-chloride ratio appears to be a sensitive indi-
cator of waste migration.

Stream-temperature characteristics

Intermittent water-temperature measurements
collected at 147 stream-gaging stations in Georgia
were analyzed by T. D. Steele and T. R. Dyar by
means of a harmonic curve-fitting technique. Re-
gional analyses of data for most unregulated
streams indicate a high degree of correlation of
both harmonic mean temperatures and seasonal
variation with the latitude of the measurement site.
The altitude of a gaging-station site is an impor-
tant variable for predicting water temperatures in
the northern mountainous part of Georgia.

Harmonic analyses of temperature measurements
for highly regulated rivers such as the Savannah
and the Chattahoochee largely reflect the influence
of reservoir releases and thermal powerplants.
Time-trend analyses of those sites with relatively
long records clearly reflect changes in stream-tem-

GEOLOGY AND HYDROLOGY APPLIED TO THE PUBLIC WELFARE

perature patterns that were caused by man’s ac-
tivities.

Central Illinois urban-runoff study

Four gaging stations and one precipitation re-
corder have been established on Sugar Creek and
its tributaries in the Bloomington-Normal area to
study the water-quality aspects of combined. sewer
runoff. B. J. Prugh, Jr., reported that water samples
are collected at monthly intervals and during storm
events in an effort to develop concentration hydro-
graphs for the various parameters being studied.
Items such as coliform bacteria, chlorides, sus-
pended solids, nitrogen and phosphorus compounds,
organic carbon, pesticides, herbicides, and 10 com—
mon metals are being examined along with dis—
solved oxygen, pH, conductivity, discharge, and
rainfall.

Investigation reveals source of mineralized water in
southwestern Kansas
Naturally occurring contamination of ground
water was identified by E. D. Gutentag, D. H. Lob—
meyer, and S. E. Slagle at four sites in Meade and
Seward Counties Where fresh ground water in un-

consolidated deposits of Pleistocene age is hydrauli-,

cally connected to highly mineralized water in un-
derlying rocks of Permian age. Water-level meas-
urements in observation wells at the sites showed
that hydraulic head in the Permian rocks is as much
as 3 m higher (adjusted for density) than head in
the unconsolidated deposits. This difference in head
caused'water containing 19,000 to 34,000 mg/l of
dissolved solids to move upward into the uncon-
solidated deposits, which generally contain water
with a dissolved-solids content of about 250 mg/l.
At the four sites where contamination was identi-
fied, water in the unconsolidated deposits contained
as much as 2,400 mg/l of dissolved solids.

Graphic computer displays aid water-quality evaluation

Isopleth maps of DO concentration were devel-
oped by S. P. Larson, W. B. Mann IV, and T. D.
Steele for a 177-km segment of the Mississippi
River in the Minneapolis-St. Paul, Minn., metro-
politan area. A general-purpose computer contour-
ing program was used to draw isopleths based on
periodic monthly sample data collected for 1971—
73 at 13 stations. The lowering of DO concentra-
tions downstream of waste-water discharge points
is evident during periods of low flow. Dilution dur-
ing periods of high flow is also clearly evident. In
general, the isopleth maps provided a means of con—

 

223

current graphic evaluation of the spatial (location
along the river) and temporal variations of DO
concentration.

Time-series and time—trend analyses of 35 to 47
yr of data at five stations indicated significant
changes in some water-quality variables subsequent
to construction of the major metropolitan waste-
treatment plant in 1938. Diversion of most of the
domestic waste load from the river through the
combined sewer system for treatment is evidenced
by decreased BOD and coliform levels and increased
D0 concentrations at stations upstream from the
treatment plant. Although water at stations down-
stream from the plantvwas affected by treatment
efl‘luent, changes in water-quality characteristics
subsequent to plant construction can be detected by
graphic time-series analyses.

Nitrate in the water of a supply well at Hawthorne Naval
Ammunition Depot, Nevada

On the basis of hydraulic and chemical data from
the supply well at the Hawthorne Naval Ammuni-
tion Depot and 17 nearby test wells, A. S. Van
Denburgh and F. E. Rush concluded that as much
as 20 mg/l of nitrate (as nitrogen) originates in
sewage ponds 370 m from the supply well. The
percolating sewage effluent is contaminating ground
water in the upper alluvial aquifer, which is about
23 m deep. The contaminated ground water has also
moved downward from the upper aquifer (prin-
cipally by leakage through a 152-m supply well dur—
ing long periods of disuse) to locally contaminate
deeper alluvial aquifers.

Effect of sludge disposal on ground-water quality

The controlled land disposal of anaerobic digested
sludge is being studied in Ocean County, N.J., to
determine several factors, one of which is its effect
on the shallow ground-water system. Three differ-
ent soil-type sites have been subdivided into 12
plots; each plot receives a different application of
sludge, consisting of about 5 percent solids, at a
rate of from 22 to 90 t ha“1 yr—l. William Kam
(Kam and J. J. Murphy, 1974) reported that pre-
liminary results indicate that ground-water con-
tamination is greatest under the 90—t/ha plot. Dur-
ing the 575 d since the start of sludge application
in June 1973, the nitrate-nitrogen concentration in-
creased from 1ess,than 1 mg/l to about 65 mg/l
under one of the 90-t/ha plots, 7 mg/l under one
of the 45—t/ha plots, and about 9 mg/l under one of

the 22-t/ha plots.

224

Impact of land-use change on water quality

The suburbanization of rural Winslow Crossing
(formerly Sicklerville), N.J., has had its greatest
impact to date on the area’s surface- and ground-
water quality. J. J. Murphy reported that sediment
loads, carried by storm runoff from land being pre—
pared for home construction, have increased from
4.5 to \450 t/ha. As homes are completed and oc-
cupied,‘ the sediment load is gradually diminishing.
Conversely, the nutrient, pesticide, and toxic-metal
load in the streams and bottom sediments is increas—
ing. Small storm-runoff detention ponds within the
developed areas exhibit thin layers of algae on their
surfaces during the summer months.

Sewage disposal by means of infiltration ponds
has resulted in contamination of the aquifer sur-
rounding the sewage-plant area. Nitrogen content
in nearby observation wells has reached 30 mg/l.
The shallow water-table aquifer discharges to
nearby Fourmile Branch Creek, and the nitrogen
loading of this stream is gradually increasing.

Ground-water contamination by landfills

Plumes of leachate-contaminated ground water
emanating from two solid-waste landfills were
mapped in the upper glacial aquifer on Long
Island, N.Y., by G. E. Kimmel and O. C. Braids
(1975). The contaminated water flows, because of
density differences, to the bottom of the aquifer
and then} downgradient for 3,000 m and 1,500 m
from the‘ two landfills. Dispersion of the contami-
nants does not extend laterally more than 100 m in
the 3,000 m of travel, but longitudinal dispersion
is considerable. The coefficient of longitudinal dis-
person is estimated to be 9.3, mZ/d.

Ground water near the landfills is characterized
by dissolved-solids concentrations of as much as
3,000 mg/l, organic-carbon concentrations of as
much as 2,250 mg/l, and an extremely pungent odor.
Much of the obnoxious character of the water, how-
ever, is lost within a thousand metres of the land-
fills, although the contaminated water remains
higher than ambient water in Na, Ca, H003, Cl,
and, in some instances, 80,. Of the elements As,
B, Cd, Co, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sr, and Zn,
only Fe, Mn, and Se were found to exceed the
standards set by the USPHS for drinking water.

Ground-water temperature was as high as 28°C.
Most of the heat generated by the landfills is not
carried far downgradient with the contaminants
but is dissipated near the landfills.

 

GEOLOGICAL SURVEY RESEARCH 1975

Stream reaeration measurements made with radioactive tracers

R. S. Grant (USGS) made reaeration measure-
ments on 10 small Wisconsin streams (0.01 to 1
m3/s) by using radioactive tracers and following
procedures developed by E. C. Tsivoglou (EPA)
(1972). Tracers were released near sewage—treat-
ment-plant outfalls, and the Wisconsin Department
of Natural Resources collected BOD data to be used
with the reaeration data for waste-load allocation
studies on three of the streams. Measured reaera-
tion coefficients (base 6 at 20°C) ranged fro-m 1.56/
d (Q=0.2 m3/s) for a short riffie—free reach to 49.5/
d for a steep pool and riflle reach. Evaluation of the
coefficient 0 in the predictive model, K2=c(h/t), is
in progress; K2 is the base 6 reaeration coefficient
(per hour) for a given reach, h is the drop in water-
surface elevation in the reach (in metres), and t
is the time of flow through the reach (in hours).

ENVIRONMENTAL GEOCHEMISTRY ..

Geochemical survey of Western coal regions

An interdisciplinaryreconnaissance geochemical
survey of those regions of the Western United
States containing economic deposits of coal has
been underway since July 1973. This work is di-
rected especially toward an aspect of geochemical
variability that is particularly difficult to come to
grips with: testing for the presence of regional geo-
chemical patterns in near—surface landscape mate-
rials. The work is patterned after the recently com-
pleted geochemical survey of Missouri (US. Geo-
logical Survey, 1973, p. 225—227) and is intended
to establish geochemical baselines for the coal-basin
landscapes against which future changes can be
measured. Work to date has focused on the northern
Great Plains and the Powder River Basin and has
covered large parts of North Dakota, South Dakota,
Montana, and Wyoming, as well as southern Sask-
katchewan.

R. R. Tidball, J. A. Erdman, and R. J. Ebens, in
a geochemical study of ground lichen (Parmelia
chlorochroa), sagebrush (Artemisia tridentata),
soil, and soil parent in the Powder River Basin,
found that only boron in the soil parent (C hori-
zon) and copper, lead, fluorine, and mercury in
ground lichen (the first two elements being meas-
ured in lichen ash) exhibit statistically significant
variation at scales larger than about 10 km in the
basin (US Geological Survey, 1974b). This gen-
eral lack of important broad-scale variation indi-
cates that basinwide patterns, if present, tend to
be weak; any attempts to map them would be

GEOLOGY AND HYDROLOGY APPLIED TO THE PUBLIC WELFARE

costly. Moreover, the absence of important basin-
wide patterns means that a basinwide baseline can
be defined rather simply as an “expected” concen-
tration or an “expected” range of concentrations.
Such ranges for a few trace elements of especial en—
vironmental interest are listed here:

Powder River
Basm

Sampling “baseline"
Element medium (ppM)
Cd _______ Sagebrush ash 2.0—18
Cd _______ Lichen ash 1.3-9.3

Hg ______ Sagebrush (dry material) 0.012—0.041
Mo ______ Sagebrush ash 3.2—17
Pb _______ A-horizon soil 11—34
Pb __- _____ B—horizon soil 12—28
Pb _______ C—horizon soil 12—25
Se _______ Sagebrush (dry material) 0.055—1.7

The range is that expected to be found in 95 per-
cent of a suite of randomly selected samples from
the basin. Samples with concentrations outside
these ranges must be viewed as highly unusual.

An independent study of trace-element variation
in surface soil and sagebrush (A. tridentata) in the
basin by J. J. Connor, J. R. Keith, and B. M. Ander-
son confirmed the general lack of significant basin-
wide geochemical patterns in these materials.

Erdman, in a continuing study of the “species
effect” in plant chemistry, determined that big
sagebrush (A. tridentata) is distinct from silver
sage (A. cana) in 9 of 21 chemical properties meas-
ured. Ash of A. tridentata is significantly higher in
Al, Cr, Fe, Ti, and V and significantly lower in B,
Mg, and Sr and also produces significantly less ash
upon combustion than A. coma.

Urban geochemistry

Geochemical maps of surficial materials in the
Front Range urban corridor demonstrate the promi-
nent control of the geochemical environment by the
geologic substrate. H. A. Tourtelot and H. G. Nei-
man (1974) reported that B, Co, Cr, Cu, Ni, Sc,
and V are significantly more highly concentrated in
areas underlain chiefly by fine-grained rocks of
Cretaceous age than they are in areas underlain by
rocks of Tertiary age or young wind-blown deposits.
In contrast, barium, yttrium, ytterbium, and zir-
conium display low concentrations in areas under-
lain by Cretaceous rocks and high concentrations in
areas underlain by Tertiary rocks. Imposed upon
this basic pattern are local areas exceptionally high
in Cu, Pb, Zn, Hg, Mo, Ag, and Sn; these metals
are thought to reflect additions from urban tech-
nological activities (US. Geological Survey, 1974c,
p. A205).

 

225

One activity that may have an important effect
on the geochemical environment is disposing of
metal-rich sewage wastes by plowing them into
agricultural land. Tourtelot, in cooperation with
J. A. Erdman (USGS) and Burns Sabey (Colorado
State Univ.), investigated the trace-element
changes in wheat grown in sewage-treated experi-
mental plots. Preliminary results suggest that ad-
ditions of up to 55 tonnes (dry) of sewage per acre
result in little change in the total metal concentra-
tion in soil, with the noticeable exception of copper
and silver. However, the ash of wheat grains grown
on treated plots is significantly higher in Ni, Fe,
Mn, and Zn and significantly lower in A1 and Ba.
Nickel exhibits the strongest response.

Geochemistry and health

R. A. Tidb‘all (USGS) and L. A. Selby (Univ.
of Missouri) reported that a significantly high pro-
portion of the variations in birth defects reported in
swine in Missouri for the years 1969—71 can be
described in terms of the gross soil chemistry of the
State. Techniques of stepwise multiple regression
result in the prediction equation:

DF= 69 — 0.6 log Na+ 2.110g Ti —— 930 \/P
+ 3,800P—23,000P2+ 78,0001)3

where DF is an estimate of the square root of the
total birth defect rate in swine by county and Na,
Ti, and P are mean soil concentrations of sodium,
titanium, and phosphorus, respectively, in percent
by county. The terms on the right account for 46
percent of the variation in DF. Variations in spe-
cific defects related to sensory organs, sex organs,
and legs in newborn swine are also moderately well
described in terms of soil phosphorus. The import-
ance of phosphorus in predicting these defect rates
may reflect some aspect of the extremely important
role this element plays in physiological processes.

LAND SUBSIDENCE

Studies of land subsidence caused by the intensive
withdrawal of ground water continued in Arizona,
California, Louisiana, Nevada, and Texas. Multiple-
depth extensometers were installed in Texas and
Baton Rouge, La., to measure changes in the thick-
ness of aquifer systems subject to stresses exceeding
preconsolidation stress; the deepest extensomete-r
wells are about 900 m deep and utilize free pipes
rather than anchored cables. The stress-strain rec-
ords from these sites, together with those from ex-
tensometers in Arizona, California, and Nevada that

a

226

have been operating for 5 to 15 yr, should add con-
siderably to the knowledge of the mechanical and
hydrologic properties of compressible aquifer sys-
tems and the storage characteristics of the inter-
bedded clayey aquitards and confining beds.

Sinkhole problems-in Alabama

J. G. Newton (1975), in a cooperative investiga-
tion with the Alabama Highway Department, evalu-
ated most areas of recent sinkhole activity in Ala-
bama. Sinkholes, as related to cause, are defined as
“induced” and “natural.” Induced collapses are by
far the greatest problem. It is estimated that 4,000
induced collapses or related features have occurred in
Alabama since 1900, most of them since 1950, where-
as records indicate that fewer than 50 natural col-
lapses have occurred since 1900; a significant number
of these natural collapses may have been related to
man’s activities.

Mos-t induced sinkholes are caused by declines in
the water table; others are caused by construction.
Collapses due to construction are caused mostly by
diversion and concentration of drainage over air-
filled openings in bedrock. Few induced collapses
result from roof failures of openings in bedrock; al-
most all‘result from failures of the roofs of cavities
in unconsolidated deposits that form where deposits
migrate downward into openings in underlying
bedrock.

Some degree of solution of carbonate rocks pre-
cedes the development of all natural sinkholes. The
first displacement of the land surface forming a new
natural sinkhole results from the continuous solution
of bedrock, a natural decline in the water table, or a
combination of both. The displacement generally oc-
curs in one of three ways: (1) Roofs consisting of
bedrock or of unconsolidated deposits collapse into an
opening in bedrock progressively enlarged by solu-
tion; (2) cavities in unconsolidated deposits that
have formed asaresult of their downward migration
collapse into underlying openings in bedrock; and
(3) slow subsidence results from solution of the up-
per surface of bedrock or the downward migration
of unconsolidated deposits in areas where the rate of
subsidence exceeds the rate of deposition. All natural
collapses in Alabama are comparable in size to in-
duced sinkholes.

Many sinkholes develop with little or no warning;
others are preceded by recognizable features that
can be observed on the ground and from the air.
Aerial photography and other remote-sensor imagery
are used to locate sinkholes and related openings,
lineaments, water loss, and vegetative stress or

 

GEOLOGICAL SURVEY RESEARCH 1975

anomalous plant Vigor. This information, combined
with geologic and topographic maps and available
water records, allows an evaluation of sinkhole haz-
ards with a minimum of fieldwork along proposed
highway corridors.

Monitor wells installed in Baton Rouge, Louisiana

Large concentrated withdrawals of ground water
in the Baton Rouge, La., area had increased to about
5.7x 105 m3/d by 1970 and are projected to increase
to about 11.4)(105 m3/d by 1980, according to G. T.
Cardwell. The artesian head in the eight principal
aquifers in the freshwater section, which extends to
a depth of about 880 m, has declined sharply in re-
cent years. Water-level declines from initial condi-
tions range from a minimum of 35 m (“2,800-ft”
sand) to a maximum of about 140 m (“2,000—ft”
sand) and averages about 60 m for all aquifers. Lev-
eling by the National Geodetic Survey (formerly the
US. Coast and Geodetic Survey) in 1965 indicated a
maximum subsidence of about 30 cm for the period
1934—65, and measurable subsidence covered 650 km2
in a bowl-shaped area generally coinciding with the
cone of depression. Leveling in 1969, which was part
of a Louisiana Water Resources Research Institute
project, indicated 9 cm of subsidence in the center of
the pumping cone.

In recognition of the need for better information
on the rate of subsidence, particularly in the heavily
pump-ed area, the USGS began a data-collection pro-
gram in fiscal year 1974, in cooperation with State
and local agencies. Three specially constructed wells,
equipped with extensometer and water-level record-
ers, were completed. The extensometers monitor
compaction or expansion of sediments to depths of
254, 518, and 913 m, which represent the shallow,
intermediate, and deep aquifer zones, respectively.
The wells are also constructed so that head changes
for the “GOO—ft,” “1,200-ft,” and “2,800-ft” sands can
be monitored.

Land-surface subsidence near Texas City and Seabrook, Texas

R. K. Gabrysch and C. W. Bonnet (1974) reported
that pumping of water from the subsurface in Harris
and Galveston Counties, Tex., has caused declines in
fluid pressure, which in turn have resulted in subsi-
dence of the land surface at Seabrook in Harris
County and,Texas City in Galveston County. With-
drawals of water by large-capacity wells began in
Harris County in the 1890’s and in Galveston County
about 1894. Artesian-head declines of as much as 73
m in the town of Seabrook and 46 m at Moses Lake

GEOLOGY AND HYDROLOGY APPLIED TO THE PUBLIC WELFARE

near Texas City have caused 1.01 m of subsidence in
Seabrook and 0.55 m at Moses Lake.

The field history of subsidence in relationship to
water-level changes and clay thickness was used to
predict ultimate subsidence. On the basis of con—
tinued loading until 1995, it was estimated that ulti-
mate subsidence in Seabrook and at Moses Lake
would be 3.0 and 1.4 m, respectively.

Subsidence bench-mark network established in Tucson, Arizona

A network of leveling controls was established in
the Tucson, Ariz., area to monitor possible land sub-
sidence caused by ground-water pumping, according
to E. S. Davidson. The network extends from bedrock
bench marks across areas of maximum water-level
decline and the thickest sections of water-bearing
deposits. Where available, old level lines were incor-
porated in this network. Preliminary results indicate
less than 1 cm of subsidence on any of the old lines
during the 30 to 40 yr since leveling began.

Land subsidence in southern Idaho caused by ground-water

withdrawal

In an area of land subsidence north of Malta,
Idaho, heavy ground-water pumping has caused wa-
ter levels to decline more than 42 m, according to
B. E. Lofgren. Relevelin‘g of bench marks along State
Highway 81 in the autumn of 1974, in conjunction
with geothermal studies in the Raft River valley, in—
dicated that there had been as much as 0.8 m of
subsidence since 1934 in an affected area of about
100 kmg. A northwest-trending earth fissure first
recognized in the early 1960’s apparently was caused
by horizontal seepage stresses on the westernlmar-
gin of the subsidence depression.

Land-surface changes in San Jacinto Valley, California

A detailed analysis of 4 yr of correlative records
of water-level, extensometer, and land-surface
changes suggests that there are three types of ver-
tical ground movement in the San Jacinto Valley,
Calif., according to B. E. Lofgren (1976): (1) An
elastic undulation of the land surface of about 0.02
m/ yr in close response to roughly 15 m of seasonal
water-level fluctuation-s; (2) a long—term compaction
of water-bearing deposits of about 0.001 m/ yr; and
(3) a deep settlement of 0.003 to 0.006 m/ yr, proba-
bly caused by continuing downfaulting in the graben
trough. At the extensometer site, the specific com-
paction of the aquifer system was about 1.3 X 10—2 m
of compaction per metre of artesian-head decline,

 

227

and specific expansion decreased from 1.3X10—3 to
0.95><10—3 m of expansion per metre of artesian-
head rise during the period between 1971 and 1974.

Model parameters for idealized aquitards in the Santa Clara
Valley

Twelve years of field records of stress and strain at
four sites in the Santa Clara Valley, Calif., and a
digital model were used to approximate average
values for hydrologic parameters. D. C. Helm (1975)
developed a model that computes the comp‘action of
a series of idealized aquitards from known changes
in effective stress and from assumed parameter
values. The idealized aquitard specifications (charac-
teristic thickness and number) are estimated from
the evaluation of a microlog of the real aquifer sys-
tem. By adjusting parameter values so that com-
puted compaction simulates ‘observed compaction,
the “best fit” set of parameter values is considered
to be diagnostic for the series of idealized aquitards
at a particular site. Preliminary diagnostic constant
values for the four sites in the Santa Clara Valley
are as follows: vertical hydraulic conductivity ranges
from 3.3 to 16.0><10—7 m/d; nonrecoverable specific
storage ranges from 3.3 to 13><10—4 m“; and re-
coverable specific storage ranges from 4.9 to 33X
10—0 m—l. Preliminary stress—dependent estimates
for vertical hydraulic conductivity range from 1.3 to
52X 10—7 m/ d, and, for nonrecoverable specific stor-
age, estimates range from 2.4 to 13 X 10‘4 m—l.

Land surface in Santa Clara Valley, California, rebounding

Water imports to Santa Clara County through the
Hetch—Hetchy and South Bay aqueducts averaged
about 171 hmi‘/yr in the period 1972—74—only 18.5
hm3 less than the annual pumpage. About two-thirds
of the imported water was used directly, and one-
third was delivered to spreading basins to replenish
the ground-water supply. J. F. Poland reported that,

~as a result of the increased imports and the above-
average precipitation during those years, the arte—
sian head at the longtime index well in San Jose
rose from a spring high of 21 m below land surface
in 1972 and 1973 to 18 m below land surface in 1974;
it rose to about 12 m below land surface in early
1975, the highest water level since 1946. This rise of
nearly 9 m since 197 3 was reflected in the response of
the water-bearing sediments. During 1974, the land
surface rebounded 6 mm, as measured by extensome—
ters in San Jose and Sunnyvale.

ASTROGEOLOGY

PLANETARY STUDIES

Interpretive studies of Mars

D. E. Wilhelms made a detailed comparison of
cratered terrains on Mars and the Moon. On the
basis of differing crater frequencies, three major
types of cratered terrain were mapped. The result-
ing pattern is similar on both the Moon and Mars,
except that the terrains with intermediate crater
frequencies are slightly more common on Mars. The
similarity in pattern suggests a similar cratering
history: an early heavy flux followed later by a much
lower flux. The work also pointed to the possibility of
massive flooding of intercrater areas within the cra-
tered terrain, probably by old volcanic deposits. M. H.
Carr explored possible mechanisms for the formation
of a bulge of the Martian crust centered on the Thar-
sis region. The bulge is several thousand kilometres
across and 7 km high at the center. Close to the cen-
ter are the large shield volcanoes of Tharsis, and
radial fractures extend outward from this region
to cover almost half the planet. The coincidence of
the bulge, the radial fractures, and the planet’s most
prominent volcanic region suggests that their origins
are related. Carr proposed that the bulge formed 1
to 2 by. ago and that the fractures resulted from
crustal extension during its formation. Volcanism
was later preferentially located at the center of the

bulge, partly because the intense fracturing allowed .

easy egress of magma to the surface.

Systematic geologic mapping of Mars

A program of systematic geologic mapping of Mars
at a scale of 1:5,000,000 by both university and
USGS personnel is approximately one-third com-
pleted. In the 11 quadrangles so far mapped, channel
deposits generally are in the upper part of the strati-
graphic column. They appear to be the same age as
the younger plains materials and younger than the
volcanic features. However, most of the area map-
ped so far is within the densely cratered terrane
where volcanic features are generally older than
those in the sparsely cratered plains. The relative
ages of the channels and the volcanic features of the

228

 

plains are still to be determined. The plains range
widely in age, judging from the number of superim-
posed craters. Many have lobate flow fronts and
ridges resembling those on the lunar maria, so that
a volcanic origin is suspected. Other plains lack these
features but have numerous albedo features that
suggest an eolian origin. Several ancient volcanic
shields have been recognized in the densely cratered
terrane. The large number of impact craters super-
imposed on these shields indicates formation very
early in Martian history.

Topographic mapping of Mars

A new version of the 1 :25,000,000 topographic map
of Mars incorporates several features not included in
an earlier preliminary version made soon after com—
pletion of the Mariner 9 mission. Generalized con-
tours have been added. These were derived by com-
bining all available data on Martian elevations into
one consistent set. Terrestrial radar, occultations,
and the MM’71 ultraviolet spectrometer were the
main data sources. These data were referred to a
fourth-order harmonic of the planet’s figure. Eight
1:5,000,000 topographic maps were completed, each
including shaded relief, albedo, and contours.

Viking support

A miniaturized X-ray fluorescence spectrometer
was designed, built, and installed on the first Viking
lander, which was launched toward Mars in August
1975. The instrument was tested in simulated Mar-
tian conditions and returned good-quality data, which
permitted the identification of an unknown sample.
A bench-top version of the instrument is in opera-
tion at Reston, Va. The Viking Inorganic Analysis
Experiment, which will utilize the instrument, is be-
ing directed by a team of scientists from the USGS
and other institutions: Priestley Toulmin III and
H. F. Rose, Jr. (USGS), A. K. Baird (Pomona Col-
lege), B. C. Clark (Martin Marietta Corporation),
and Klaus K'eil (Univ. of New Mexico) .

Mercury

In 1974, Mercury joined the Earth, the Moon, and
Mars as a planet for which enough detailed informar

ASTROGEOLOGY

tion is available to make meaningful geologic com-
parisons. Mariner 10 flew by Mercury on March 29
and September 21, 1974, and returned over 2,000
close-up pictures. The closest planet to the Sun and
one of the smallest major planets, Mercury bears
some striking resemblances to and has some in-
triguing differences from the Moon (Trask and
Guest, 1975) .

The Mercury pictures support the view that ter-
minal heavy bombardment, dated from lunar sam-
ples at about 4 b.y., was an episode that character-
ized the entire inner solar system. The Earth very
probably also underwent a comparable bombard-
ment, which must be included in any reconstruction
of terrestrial history. The largest impacts on the
Moon and Mercury produced huge basins that were
probably excavated initially to a depth of 100 to 200
km; permanent modification of the host material
certainly occurred to some appreciably greater depth.
Many such events on Earth 4 by. ago must have
created physical and chemical heterogeneities in the
upper mantle and probably reset all radiometric
dates.

LUNAR INVESTIGATIONS

Lunar basins

Photogeologic investigations combined with data
from lunar mapping, cratering experiments, and
remote sensing resulted in revised interpretations
of lunar impact-basin development and morphologic
expression of accompanying structures and deposits.

J. F. McCauley proposed a revised model for the
Orientale basin. In this model, the original rim of
the crater formed by the impact event is generally
coincident with the crest of the Rook Mountain ring
some 600 m in diameter. The knobby material of
the Rock Mountain unit, previously described as
secondary slump products, is now considered to re-
sult directly from the cratering event; its texture
and distribution pattern suggest that it is the upper-
most part of the overturned flap of the crater rim
and that it overlies the radially lineated Hevelius
Formation. The coarse knobs represent coherent
material quarried from well beneath the lunar low-
velocity surface layer (depth about 25 km) that
was churned up by pre-Orientale saturation bom-
bardment. These relatively coherent blocks, now
seen as widely scattered knobs, had their source
deep within the transient crater. Since these ma-
terials were the last to leave the crater, they had
considerably less radial momentum than the other
ejecta facies associated with Orientale, and they

 

229

were partly confined by the outer ring fault now
marked by the Cordillera scarp. The Hevelius For-
mation, now exposed mostly outside the Cordillera
scarp, is ejecta of shallower origin; it is an earlier
excavation product that was less cohesive than the
knobby unit. The formation consists of ballistically
redistributed debris from the heavily cratered
upper part of the pre-Orientale surface, and this
unit, like its counterpart, the Fra Mauro Forma-
tion, records a complex multiplicity of cratering
events. The difference in the depth of the source
region and the greater radial momentum together
account for the distinctive braided appearance.

Ejecta relations similar to those around Orientale
are seen in the DOD’s experimental crater Dial
Pack, which is located in Nevada. Preliminary study
and mapping by D. J. Roddy of the structures seen
on the floor of this crater and that of the Prairie
Flat crater, also in Nevada, suggest that anticlines
and domes are present on the floors of these experi-
mental craters, and Roddy and McCauley inter-
preted the ridges and domes seen within the
crackled inner-basin unit of Orientale as analogous
compressional features. These features are formed
late in the cratering event by inward motion of
deep-seated material. The preparation of structural
sketch maps of the interior of the basin has led to
the recognition of numerous radial faults hundreds
of kilometres in length that cut the inner rings into
segments and that locally extend outward through
the Cordillera scarp. Translations on individual
blocks appear to be in the inward direction and to
be controlled in part by the lunar grid. These move—
ments are considered to have occurred during the
cratering event and are not thought to be related
to postcrater slumping. They appear to be similar
in general character to some of the tear faults in
the walls of Meteor Crater as it was originally
mapped by Shoemaker.

D. H. Scott used gravity data to calculate the
volume of the Orientale basin where topographic
control is inadequate for reliable estimates of basin
geometry. The results indicate that the present
volume of Orientale is about 2X10G kma but that
the original volume, and thus the amount of ma-
terial ejected, must have been more than 5 X 106 km3.
Stratigraphic studies using these results, combined
with mapping of the ejecta blanket and its distribu-
tion, by McCauley and Scott resulted in the subdi-
vision of the Orientale ejecta blanket into six dis-
tinct stratigraphic units. These stratigraphic units
will be designated as members and formations, and
all basin-related materials will be elevated to group

230

status. The new mapping reconfirmed the asym-
metry of the basin ejecta, which are. thought to re-
flect nonvertical incidence of the impacting bolide
or the influence of older nearby basins on rock
strength, fracture propagation, and the formation
of topographic barriers.

Geologic remapping on the central near side of
the Moon (50° N. to 50° 8., 50° E. to 50° W.) by
D. E. Wilhelms, which incorporated the results
from sampling and remote-sensing missions of the
last 5 yr, led to a reevaluation of features now
thought to be related to impact basins. In particu-
lar, the rock samples returned by Apolloyhave neces—
sitated reinterpretation of certain mantles, plains,
hills, pits, and furrows of the terrae that were pre-
viously thought to be of volcanic or tectonic origin.
Most such features on the central near side are now
seen to be related to impact basins, especially Im-
brium, but also to the younger Orientale and the
older Nectaris, Humorum, Serenitatis, and Crisium
basins. For example, the Descartes Mountains at
the Apollo 16 site are believed to consist of primary
and secondary Imbrium material overlying Nectaris
material. Secondary craters of basins and the
masses of basin ejecta that flowed along the sur-
face are more extensive than was once thought. The
ground ejecta arrives at a given radial distance
from the basin later than the secondaries. The re-
sulting override of the secondaries produces many
of the complex superposition relations that once
seemed to require volcanic origins.

Also pertaining to lunar impact basins are studies
of gravity anomalies found on the Moon’s near side
by the Apollo missions and evaluated by Scott.
Some of the positive anomalies are nearly circular
and probably represent previously unrecognized
basins or subbasins. Two lie along a line connecting
the Serenitatis and Nectaris mascons; one is cen-
tered over the crater Lamont and the other near the
old crater Torricelli R north of Theophilus. The
gravity data show the probable presence of a large
mascon in northern Mare Serenitatis substanti-
ating previous geologic mapping, which postulated
that the northern part of this basin was formed by
separate impact. Gravity values obtained at two dif-
ferent spacecraft altitudes over Lamont allowed
some discrimination in calculating the configuration
and depth of this mascon. Calculations indicated
that adisk-shaped mass having a radius of about
85 km and a thickness of about 1.8 km would pro-
duce the anomaly observed at both altitudes.

Compilation by Scott, J. M. Diaz, and J. A. Wat-
kins of all lunar morphologic features believed to

 

GEOLOGICAL SURVEY RESEARCH 1975

be associated with volcano-tectonic processes such
as ridges, troughs, rilles, domes, cones, and linea—
ments indicated that two major mare—ridge sys-
tems are present on the Moon: (1) basin-concentric
ridges associated with circular mascons and (2)
long linear ridge systems in Oceanus Procellarum
that appear to correlate with positive gravity
trends. The magnitudes of the gravity anomalies
associated with the linear ridge systems are much
less than those of the circular mascons. It is thus
suggested that a large number of basaltic dikes in

themselves are not primary contributors to mascon

gravity anomalies. Thus, pluglike mascon models
possibly extending through the crust to the lunar
mantle seem more appropriate than relatively thin
disk~shaped mascons supported by the crust and
fed by dikes.

Apollo 17 mission results

B. K. Lucchitta, V. S. Reed, G. E. Ulrich, A. G.
Sanchez, and E. W. Wolfe continued to study the
Apollo 17 landing region. Using both photogeologic
interpretation and the gravity data of D. H. Scott,
which indicate that Mare Serenitatis is underlain
by two basins instead of one, Wolfe and Reed sug-
gested that the Apollo 17 landing area is located ap-
proximately at the third ring of a basin structure
similar to but slightly larger than the fresher
Orientale basin. The strikingly similar shapes,
sizes, and distributions of the massifs and sculp-
tured hills in the Taurus-Littrow area and the
massifs and related knobby-textured terrane in the
outer Rook Mountain ring (ring 3) of the Orientale
basin indicate that these are analogous structural
features. Extrapolating from ring 3 of the Orientale
structure, which has been interpreted as the ap-
proximate rim of the transient cavity, to the slight-
ly larger third ring of the southern Serenitatis
basin structure, Wolfe and Reed estimated that per-
haps 15 km of ejecta was emplaced adjacent to the
southern Serenitatis transient cavity. Subsequent
development of the ring structure and the radial
grabens and emplacement of more ejecta created
the mountainous landscape that was later flooded
by mare basalt to form the Apollo 17 landing
valley.

The investigative team summarized the geology
of the landing valley as follows: the radial graben
in whichthe Taurus—Littrow valley is located was
partially filled by about 1,400 m of basaltic lava.
The uppermost part, texturally variable but chemi-
cally uniform olivine-normative basalt, may be on
the order of 100 m thick. Large boulders of quartz-

.ASTROGEOLOGY

normative basalt on the rim of Camelot Crater may
represent an underlying flow unit. Basalt extrusion
in the valley terminated about 3.75 b.y. ago and was
quickly followed by deposition of a unit of glass
beads of probable pyroclastic origin. A remnant
of this unit in the Shorty Crater target is repre-
sented by orange and black droplets on the Shorty
Crater rim. The glass—bead unit in combination
with the overlying regolith forms an unconsolidated
surficial deposit with an average thickness of about
14 m, thick enough to permit abnormally rapid de-
gradation of the smaller craters, especially those
<200 m, so as to create a subdued appearance.
Admixture of glass-bead material gives the surface
a distinctive dark color, which, in combination with
its subdued appearance, led to the erroneous pre-

mission interpretation of a young dark mantling

unit of pyroclastic origin. Impact-generated regolith
consists mainly of local materials from the subfloor
basalt, the glass-bead unit, and the nearby high-
lands. In its upper part, the regolith contains basalt-
rich ejecta from crater clusters that pepper the
valley floor. Most of the craters are part of a sec-
ondary cluster formed by projectiles from Tycho;
the light mantle is a deposit of secondary ejecta or
an avalanche or both, set in motion by the impact
of Tycho secondary projectiles on the South Massif.
The central cluster and the light mantle, and hence
Tycho, were probably formed between 15 to 20
and 70 to 95 my. ago.

In order to elucidate the relationship between
dark mantle and orange materials in the landing
area, Lucchitta (USGS) and H. H. Schmitt
(NASA) investigated a dark mantle area on the
opposite side of the Serenitatis basin. Orange and
red material had been observed and photographed
during the Apollo 17 orbital paths in that area,
and a later examination of photographs showed
that it occurs only within the dark mantle that
overlies old rilled mare and highland units and is
absent on the younger mare unit in this area. The
orange and red material occurs predominantly as
halos, patches, or rays around fresh impact craters
ranging in diameter from less than 50 to 250 m
and in layers exposed at the base of the dark mantle
deposit in the sweep walls of a depression and a
graben. Red material is present in the highland
subsurface, possibly as dikes. The study suggested
that orange material, locally underlain by red ma-
terial, occurs in the dark mantle to a depth of
about 50 m as locally stratified but discontinuous
pyroclastic materials that erupted during the later
stages of accumulation of the older mare basalt

 

231

units. These observations confirm that the geologic
settings of dark mantle areas on both sides of
Mare Serenitatis are similar.

Craters

Testing extraterrestrial craters and candidate
terrestrial analogs for morphologic similitude was
treated by R. J. Pike as a problem in numerical
taxonomy. According to a principal-components
solution and a cluster analysis, 402 representative
craters on the Earth, the Moon, and Mars divide
into two major classes with contrasting shapes and
modes of origin. Craters of net accumulation of
material (cratere-d lunar domes, Martian “calderas,”
and all terrestrial volcanoes except maars and tufi'
rings) are in a group apart from craters of excava-
tion (terrestrial meteorite-impact and experimental
explosion craters, typical Martian- craters, and all
other lunar craters). Maars and tuf’f rings belong
to neither group but are transitional. The classifi-
cation is based on criteria of topographic geometry.
Of these, the morphometric differences between
crater bowl and raised rim are the strongest. Al-
though single topographic variables cannot confi-
dently predict the genesis of individual extrater-
restrial craters, multivariate statistical models
constructed from several variables can distinguish
consistently between large impact craters and vol-
canoes.

TERRESTRIAL ANALOGS
AND EXPERIMENTAL STUDIES

CRATER INVESTIGATIONS

Lonar Crater

A geologic investigation of Lonar Crater in Ma-
harashtra, India, by the Geological Survey of India,
i‘Nith the participation of D. J. Milton (USGS), has
been in progress. The crater is 1,830 m across and
nearly 150 m deep. It is similar in structure, age, and
state of preservation to the better known Arizona
Crater. The crater is in the Deccan Traps, the only
terrestrial crater known in basalt, and so presents
petrographic features particularly analogous to cra-
ter materials on the Moon. Earlier results (Fredriks—
son and others, 1973) for the first time established
the impact origin on the basis of shock features, in-
cluding shock—melted basalt bombs and spherules in
the ejecta, isotropized plagioclase in moderately
shocked fragments, and shatter coning in weakly
shocked breccia in drill cores in the crater floor. As

232

yet, no meteoritic material has been identified. Cur-
rent investigations center on the mode of deposition
of the ejecta. Ejecta-filled depressions in the sub-
strate near the outer margin of the ejecta blanket
are apparently secondary impact craters. Fragments
of substrate soil are incorporated into the basal
parts of the ejecta blanket. Their distribution is be
ing studied for its relevance to the mixing of lunar
breccias.

Ries Crater studies

A complete suite of shocked granodiorites from
the Ries Crater suevite was assembled by E. C. T.
Chao, J. A. Minkin, and C. L. Thompson and classified
according to the degree of shock from 1 to 7 on the
basis of shock features observed in quartz, plagio-
clase, and b-iotite. The correlation of microscopic and
megascopic classifications of the degree of shock was
established for the first time.

Samples of shocked granitic pegmatite from Lake
Lappajarvi, Finland, were chosen for detailed sys-
tematic study by optical, X-ray, and electron micro-
scope techniques. These samples, the best naturally
shocked specimens that the investigators have seen,
contain large single crystals of shocked quartz and
feldspar and cover a complete range of the degree of

shock. Several single crystals of shocked quartz .

studied by X-ray precession technique were all found
to be Dauphiné twinned, even crystals that were only
very weakly shocked as judged by refractive indices
and lack of lamellar features. The consistent presence
of Dauphiné twinning in weakly shocked quartz
crystals indicates that it may be a dominant form of
yielding in quartz at low shock pressures.

Elko craters, Nevada

A field of probable impact craters near Elko, Nev.,
was studied in reconnaissance by D. J. Roddy. An
aerial search extended the known length of the field
from 20 to 21.5 km to the northeast, with a maximum
width of 2.7 km. The total number of craters recog-
nized now exceeds 200. Aerial reconnaissance of
many hundreds of square kilometres surrounding
this area located only one other small field 8 km west,
which contains several small craters less than 10 m
in diameter. The larger craters in the main field are
as deep as 3 m and have well-defined rims. Both
single and multiple craters are common; the largest
multiple crater is approximately 250 m across. Most
of the crate-rs tend to occur in clusters of three or
more and are concentrated along a northeast-south-
west centerline; single isolated craters are most com-
mon along the outer edges of the field. The fact that

 

GEOLOGICAL SURVEY RESEARCH 1975

the crater distribution does not appear to be influ-
enced by topographic or structural control strength-
ens the impact hypotheses. Soil samples from the
largest Elko craters have been examined for mag-
netic, glassy, and shocked materials. To date, only
magnetite, derived from mineralized zones that lie
3 to 4 km to the west, has been identified.

Shock-wave-cratering mechanics, impact, and explosion
cratering

D. J. Roddy participated in large-scale explosion
experiments conducted by the DOD in both Canada
and the United States over the last decade. These
experiments have repeatedly yielded similar types of
structural deformation in craters formed from hemi-
spheres and spheres of high explosives detonated at
and above the ground surface. Structural deforma-
tion in these craters, which are up to 100 m in di-
ameter, includes central uplifts, inward and upward
movement of the crater floor, faulted, folded, and
uplifted rims, and massive overturned flaps with ray-
like extensions. Other aspects common to these cra-
ters include the ballistics and distribution of ejecta,
fused material, shatter cones, and certain types of
solid—state shock-metamorphic features, such as
planar elements formed under shock-wave pressures
in crystal lattices.

The craters formed in these explosion experiments
provided the confirmation necessary to show that
certain types of major structural deformation are
related to charge size and geometry and to height of
burst and that target media are critical but do not
control the basic styles of deformation.

Several of these cratering experiments were used
for astronaut training and in the NASA-sponsored
USGS lunar geologic surface experiments. The topo-
graphic and structural similarities between these and
earlier craters generated by surface explosions and
terrestrial, lunar, and Martian craters have been of
assistance in discussing the hypervelocity impact
origin and in understanding large-scale impact cra-
tering processes.

The cratering sequences determined in these ex-
periments reemphasize their similarities with craters
formed by hypervelocity impact and shock vaporiza-
tion of a low-density body, such as a comet, which
does not penetrate deeply and produces a surface-
generated very high energy shock wave. The numer-
ous structural similarities between these surface-
generated explosion craters and certain very large
terrestrial and lunar craters up to tens of kilometres
across suggest that this analogy can be extended to
include the largest of the natural sites. For example,

ASTROGEOLOGY

an unusually good morphological comparison can be
made between Mixed Company 3, Snowball (500-t
TNT surface hemisphere), and the lunar crater Co-
pernicus (95 km across). A similar comparison can
be made between the Prairie Flat (500-t TNT sur-
face sphere) and Dial Pack (500-t TNT surface
sphere) craters in Nevada and the ringed lunar
structure Mare Orientale (over 1,000 km across).

MINERALOGICAL INVESTIGATIONS

Mars eolian winnowing simulated

J. G. Hammarstrom and Priestley Toulmin III car-
ried out size and mineral analyses of material de-
livered to a model of the Viking X-ray fluorescence
spectrometer (XRFS) in a series of wind-tunnel tests
simulating atmospheric conditions on the Martian
surface. The original material was a mixture of
quartz, augite, magnetite, and mus-covite, each sized
to approximate the grain-size distribution of the
lunar fines. The material was dropped from a Viking
sampler head into a Viking XRFS funnel from sev-
eral heights at different wind velocities and direc-
tions. Analysis of the material that actually got into
the funnel confirmed the expected dependencies on
height, Wind, density, and shape but indicated that,
if the sampler head is placed close to the funnel, even
high winds (up to 70 m/ s) should have very little
effect on the sample composition.

Fluid inclusion studies on simulated Martian samples

Edwin Roedder studied some simulated Martian
samples in an attempt to evaluate the effects of vari-
ous suggested sterilization procedures on the scien-
tific information obtainable from a returned Mars
sample. Fluid inclusion studies are particularly ap-
propriate here in that they can yield much informa-
tion from very tiny samples, even those in the l-ng
range. Although almost any sterilization protocol
would seriously affect or totally negate the results of
at least some petrological, geochemical, or geophysi-
cal experiments performed'on the samples, Roedder
found that sterilization at 275°C for 1 d in helium at
1 atm had almost no noticeable effect on the signifi-
cance of the data obtainable from a study of fluid
inclusions. However, these results cannot necessarily
be extrapolated to higher temperatures or to other
types of sample materials.

Experimental shock research

The transmission interference microscope is a pow-
erful tool for the study of microstructures such as

 

233

closely spaced parallel fractures, twinning, and lamel-
lar structures produced by static and shock deforma-
tion. In an investigation of experimentally shocked
quartz conducted by E. C. T. Chao, it was possible to
distinguish microfractures from lamellae only by this
technique.

LUNAR SAMPLE INVESTIGATIONS

Petrology of lunar rocks

During the Apollo 17 mission, several large boul-
ders of highlands rock derived from the North and
South Massifs were sampled. Samples were selected
to represent the major rock types in each boulder,
and the field relations were carefully documented. In
recognition of the unique value of these samples,
interdisciplinary consortia of investigators were es-
tablished to study the suites of rocks from each
boulder. E. C. T. Chao led the consortium studying
samples collected frOm the boulder at Station 7. A
similar consortium led by O. B. James was estab-
lished to study two samples from Station 3 (although
these rocks were collected from regolith, they appear
to be related to samples taken from a boulder at
Station 2).

Four samples (77135, 77115, 77075, and 77215)
were collected from the boulder at Station 7. Studies
of these samples by Chao, J. A. Minkin, and C. L.
Thompson (1974) led to the following conclusions:

1. Sample 77215, the oldest of the four samples as
determined by field relations, is a breccia con-
taining fragments of norite. The norite appears
to be of relatively deep—seated origin, for it
contains orthopyroxene grains with thick ex-
solved lamellae of augite. Some impact process
excavated the norite and brought it to the
upper levels of the lunar crust.

2. Samples 77075 and 77115 crystallized from frag-
ment-laden melts that diked and enclosed, re-
spectively, the mass from which 77215 was
taken. Field relations suggest that these two
melts could have been contemporaneous,
formed by the same event.

3. The rock units from which 77075, 77115, and
77215 were taken are shock fractured as a
block; this block is enclosed by unfractured
feldspathic pigeonite basalt, represented by
77135. Sample 77135 crystallized from a frag-
ment-laden melt formed in an event that took
place after the 7707 5 and 77115 melts formed.

4. Detailed studies of 77135 suggest three possible
sources for the melt from which it crystallized:
(1) An impact melt formed by the Serenitatis

234

event, (2) an endogenous igneous melt unre-
lated to the Serenitatis event, or (3) a premare
endogenous igneous melt intruded into the wall
of the Serenitatis basin after the .basin was
formed. Regardless of the source of the‘77135
melt, this rock represents one of the maj or rock
types of the lunar highlands.

Studies of theStation 3 consortium have thus far
concentrated on sample 73215 (James, 1975a). The
bulk of this breccia consists of an aphanitic matrix
containing competent mineral and lithic clasts plus
bands and patches of granulated clastic materials.
The matrix is quite variable, and several types are
distinguishable; these vary in color, cohesiveness,
content of shear-induced porosity, and content and
composition of clast-derived schlieren. The consorti-
um studies, which thus far have been primarily of
matrix, have shown that all types of matrices consist
of abundant small lithic and mineral clasts set in a
dark groundmass of minute grain size and that the
groundmass crystallized from a melt. It is unlikely
that this breccia originated as regolith breccia or
unconsolidated regolith in which an original frag-
mental glassy matrix was melted by a shock or ther-
mal event. Instead, characteristics of the rock tex-
ture and fragment assemblage suggest that the brec-
cia represents an aggregate of impact melt (which
crystallized to form the groundmass) and pulverized
rock, all of which formed in a large impact event;
the event may have been one of the basin-forming
impacts. The rock shows well-developed structures
formed by differential flow and shear of the matrix
and clast materials, and these structures demon-
strate that shear and flow processes may have been
very important in lunar highland breccias.

One particular class of lunar breccias holds great

potential for study of the early history of the lunar‘

crust. This class formed as a result of major impacts
that generated mare basins and the largest lunar cra-
ters. Such impacts would have excavated rocks from
an extensive section of the lunar crust, and from
these a partial reconstruction of the preimpact crust
could be made. James (1975b) evaluated the differ-
ent types of lunar breccias in an attempt to identify
those that may have had major-impact origins, and
it appears that many types may indeed be related to
major impacts. Apollo 17 light-gray breccias may be
analogous to terrestrial suevites. Many different
types of lunar breccias formed as aggregates of melt
plus fragmental debris; among these are Apollo 17
blue-gray breccias, green-gray breccias, some of the
light-gray breccias, Apollo 16 poikilitic rocks, and

 

GEOLOGICAL SURVEY RESEARCH 1975

the most common types of clasts in Apollo 14 ther—
mally metamorphosed breccias and Apollo 16 friable
feldspathic breccias. These types of breccia differ
primarily in ratio of fragments to melt and crystalli-
zation history of the melt, but bulk compositions of
the aggregates are all quite similar. Rock textures
and fragment assemblages suggest that all these
types of breccia formed as aggregates of impact melt
and crushed rock gene-rated during major impacts.
Other types of lunar breccias related to major im-
pacts are (1) cataclastic anorthosites, in which the
cataclasis was the result of shock during an impact,
and (2) “black and white rocks” (which consist of
cataclasites diked by fragment-laden impact melts
and subsequently remobilized), in which the cata-
clasis, intrusion by impact melts, and remobilization
were all impact induced. ,

A glass-coated half-metre boulder was sampled
by the Apollo 17 astronauts at Station 8, near the
front of the Sculptured Hills. E. D. Jackson, R. L.
Sutton, and H. G. Wilshire (1975) studied the re-
turned samples of this boulder. The rock is a coarse-
grained (0.5 cm) plagioclase-orthopyroxenecumulate
and is the only true norite among the returned lunar
samples. Lunar surface photographs of the boulder
showed it to contain at least nine structural surfaces
and four glass veins. Hand-specimen examination of
three of the returned samples resulted in the identi-
fication of six surfaces and one vein. One of the struc-
tural surfaces visible in the boulder was identified as
a primary cumulus planar lamination folded through
an angle of at least 35° between two oriented sam-
ples; fracture sets representing the other structural
surfaces were coincident. The boulder is believed to
be a sample of the deeper highlands or submare lunar
crust, derived from a depth of 8 to 30 km; it was
somewhat shock metamorphosed during at least two
impact events. The cumulus texture of the rock pre-
cludes its being representative of any magmatic
liquid composition and suggests that plagioclase
sank, not floated, in at least some of the magmatic
liquids that formed the lunar crust. Moreover, the
evidence that cumulus processes have operated in the
lunar crust indicates that the crust is probably
heterogeneously layered.

Wilshire, D. E. Stuart-Alexander, and E. C.
Schwarzman completed a comprehensive study of
Apollo 16 breccias. They consider that all major types
were derived by rebrecciation of a first-cycle breccia
that consisted of clasts of feldspathic plutonic rock
in a matrix of fine grain size. The first-cycle breccia,
because of the nature of its clast assemblage, is
thought to represent material derived from consider-

ASTROGEOLOGY

able depth in the lunar crust and excavated by a
basin-forming event. Relict clasts that survived the
brecciation processes show that the feldspathic plu-
tonic rocks originally formed as igneous cumulates;
however, thermal metamorphism caused local re-
crystallization in most of these clasts. The first
major impact event that affected these rocks pro-
duced extensive pulverization, melting, and thermal
metamorphism. '

Wilshire (1974) summarized some of the most im-
portant characteristics of the provenance of lunar
highland breccias. These breccias contain relics of
plutonic source rocks that have had long igneous and
metamorphic histories. Most of these plutonic rocks
have extremely feldspar-rich bulk compositions. The
compositions and textures indicate that the rocks
must have formed by igneous fractionation and that
they had lengthy periods of postconsolidation an-
nealing in environments not frequently plumbed by
impact. These characteristics are consistent with for-
mation of the rocks in a plutonic environment at
depths perhaps greater than 10 km, from which they
were excavated by large basin-forming impact
events.

Edwin Roedder (USGS) and P. W. Weiblen (Univ.
of Minnesota) (1975) reported an anomalous type of
silicate melt inclusion of unexplained origin in the
Apollo 17 mare basalts. Ilmenite crystals in all seven
mare basalt samples examined contain relatively
large silicate melt inclusions. These are now either
wholly glass or glass that contains a few feathery
crystals. Bulk compositions are of two types. (Some
individual small ilmenite grains have both types of
inclusions.) The less abundant type is of potassic
granite composition (6.4 percent K20 and 76.7 per-
cent SiOZ) and formed by late-stage immiscibility of
the silicate melt; similar inclusions are found in most
lunar mare basalts and some terrestrial basalts. The
more abundant type has identical SiOz content, 76.4
percent, but only 0.03 percent K20 (average of 29
analyses) ; the difference is made up largely by an
increased CaO content, and most other oxides have
similar concentrations in the two types. At present,
none of the theories proposed for the origin of these
anomalous “low-potassium” inclusions satisfactorily
explains all the observations.

Experiments on the partial melting of pyroxenes
at 1 atm (J. S. Huebner, 1975) suggest that the
silica content of a primary mare basalt magma may
indicate its depth of origin. During partial melting
of augite, aluminum and titanium are strongly frac-
is depressed. Thus, melts coexisting with augite can
tionated into the liquid phase, and its silica activity

 

235

have as few as 1.75 cations of silicon per 6 oxygen
atoms. During partial melting of the calcium-poor
pyroxenes, orthopyroxene, and pigeonite, aluminum
and titanium are even more strongly fractionated
into the liquid phase. However, in the case of these
pyroxenes, there is a lower limit below which the
silica activity of the coexisting partial melt cannot be
depressed. If the silica content of a melt coexisting
with a calcium-poor pyroxene drops below about 1.9
cations per 6 oxygen atoms, the pyroxene is con-
verted to olivine, and silica is released to the liquid.
Experimentally produced melts coexisting with cal-
cium-poor pyroxene (and minor olivine) commonly
have about 1.9 cations of silicon and 0.5 cations of
aluminum per 6 oxygen atoms; The silicon content of
lunar mare basalts ranges from 1.66 to 1.86 cations
per 6 oxygen atoms. Therefore, these melts cannot be
in equilibrium with, or derived from the low-pressure
partial melting of, mantle consisting of calcium-poor
pyroxene plus or minus olivine. However, the increas-
ing pressure of the partial melting of calcium-poor
pyroxene will progressively decrease the silica con-
tent .of the coexisting melt. Silica contents of the
mare basalts suggest that their parent magmas may
have formed by partial melting over the pressure
range of 2 to 25 kb, the less silicic of the melts being
derived at the greater pressures.

Lunar glasses and lunar fines

R. B. Finkelman, Sol Berman, R. P. Christian,
E. J. Dwornik, J. R. Lindsay, H. J. Rose, Jr., and
M. M. Schnepfe studied the mineralogy and chem-
istry-of the ultrafine fraction of Apollo 16 regolith
samples. Some of their data were reported by Fink-
elman, Christian, Schnepfe, ”and Berman (1975).
The Apollo 16 ultrafines (less than 30 pm in size)
show a more restricted mineral assemblage than the
Apollo 14 ultrafines. The fact that particles" of
mare-derived ferromagnesian minerals are sparse
indicates that the range over which significant
transport of ultrafine crystalline particles can take
place is less than the distance from the Apollo 16
site to the nearest mare surface. The ultrafine frac-
tion has a higher excess reducing capacity than the
coarser fraction (30 am to 1 mm) ; this difference in-
dicates that the ultrafine particles have been ex-
posed at the lunar surface for longer times on the
average than the coarser particles. The ultrafines are
enrichedjn Pb, Zn, Ba, Ga, Rb, Sc, and Yb and
depleted in Co and Ni relative to the coarser frac-
tions. The observed elemental enrichments may be
due to one or more of the following processes: (1)
Volatilization and subsequent condensation (since

236

the ultrafines have a relatively greater surface area
than the coarser fractions, enrichment of condens-
ing volatiles would be greater); (2) an influx of
minute grains of KREEP-rich material; and (3)
comminution of mesostasis of locally derived rocks.

A. N. Thorpe, F. E. Senftle, C. L. Briggs, and
C. C. Alexander (1973) studied the magnetic sus-
ceptibility of 11 small glass spherules and 2 sam-
ples of a large spherical glass shell from Apollo 15,
16, and 17 fines. Measurements were made over
temperatures ranging from room temperature to
the temperature of liquid helium. All but one speci-
men showed the presence of antiferromagnetic
inclusion-s. Measurements of the magnetic suscep-
tibility on five specimens at closely spaced tempera-
ture intervals below 77°K showed antiferromag-
netic temperature transitions (Néel transitions).
In one specimen, these transitions could be ascribed
to ilmenite, but, in the other four, they do not cor-
respond to transitions in any known antiferromag-
netic compounds.

Age determinations

The uranium, thorium, and lead concentrations
and the lead isotopic compositions of selected Apollo
17 soil and rock samples were studied by Mitsunobu
Tatsumoto and P. D. Nunes. Concordia treatment
of the data for the mare basalts and highland rock
samples suggests several early thermal events ap—
proximately 4.5 b.y. ago.

Current information from all uranium-thorium-
lead lunar chronology data suggests that the Moon
had a multistage uranium-lead evolution history,
probably dominantly caused by complex planetary
bombardment from 4.5 to 3.9 by. ago. Events at
approximately 4.0, 4.2, and 4.4 to 4.5 by. are evi-
dent on whole-rock frequency versus 207Pb/W‘Pb age
histograms. Each of these events in itself probably
reflects multiple cratering episodes. For mare
basalts, it appears that complete resetting of the
source-rock uranium-lead systems was often ap-
proached after a major planetesimal impact (caused
by lead loss relative to uranium). It further appears
that, during later melting and extrusion of the
basalts, 500 to 800 my. after basin formation, the
. uranium-lead total-rock systems were negligibly
disturbed, whereas the 40Ar/39Ar whole-rock and
rubidium-strontium mineral systems were complete—
ly reset.

Chemical composition

The Surveyor 3 spacecraft landed at the Apollo
12 site 31 mo prior to the Apollo mission and

 

GEOLOGICAL SURVEY RESEARCH 1975

scooped up a sample of regolith. During the Apollo
12 mission, the astronauts retrieved the Surveyor
scoop and the lunar fines (sample 12029) therein.
The results of analyses of this material by E. J.
Dwornik, C. S. Annell, R. P. Christian, Frank Cut-
titta, R. B. Finkelman, D. T. Ligon, Jr., and H. J.
Rose, J r., led to the following conclusions: (1) The
green glass components in the fines appear to have
been derived from anorthositic norite or troctolite
parent materials; (2) the presence of a significant
meteoritic component is indicated by relatively
high nickel content, abundant metallic iron-nickel
blebs and spheres (diameters less than 20 pm) , and
sparse particles of a copper-rich phase; and (3) the
fines had a genesis and history like those of fines
sample 12070, collected on the rim of a small crater
about 165 m to the northwest.

Twenty-four samples of rocks and fines returned
by the Apollo 17 mission have been analyzed by
Rose, Cuttitta, Sol Berman, F. W. Brown, M. K.
Carron, Christian, Dwornik and L. P. Greenland.
Some of their data have been reported by Rose,
Christian, Dwornik, and M. M. Schne-pfe (1975).
The fines samples are extremely variable in compo-
sition, but these compositions fall into three broad
groups: (1) Light mantle and South Massif fines,
(2) dark mantle and valley floor fines, and (3)
North Massif fines. One of the analyzed fines sam-
ples, 76501, is unique, and its composition cannot
be explained by mixing of the three groups listed
above; it is depleted in most trace elements relative
to the other samples. The dark mantle and valley
floor fines samples are compositionally similar to
fines collected at the Apollo 11 site, except that the
former have a smaller excess reducing capacity and
a higher nickel-iron ratio than the latter; the dif-
ferences suggest that the fines at the Apollo 11 site
had a greater exposure to solar-wind irradiation but
contain a smaller meteoritic component than the
fines on the valley floor at the Apollo 17 site. The
Apollo 17 mare basalts all appear to have had a
common source; their compositions are similar to
those of the Apollo 11 mare basalts. Comparisons
of compositions of the regolith breccias and fines
samples at Van Serg Crater yield important infor-
mation on the process of breccia formation: The
breccias are identical in composition to unconsoli-
dated regolith, and they probably represent regolith
indurated or compacted during the impact event
that formed the crater.

REMOTE SENSING AND

EARTH RESOURCES OBSERVATION
SYSTEMS (EROS) PROGRAM

The EROS program continued to support and co-
ordinate the applications research involved in LAND-
SAT (formerly ERTS) experiments and remote-sens-
ing applications demonstrations Within various
Bureaus and Offices of the Department of the
Interior. Special emphasis was placed on making the
program more responsive to users’ needs; signifi-
cant improvements were made at the EROS Data
Center (Sioux Falls, S. Dak.) in production schedul-
ing, reproduction of remote-sensing data, number
and types of training programs, and staffing to assist
users with application problems.

Additional user-assistance centers, offering vary-
ing degrees of service, were developed. Comprehen-
sive services, including assistance in the ordering and
analysis of data, and access to data-manipulation
equipment and basic remote-sensing literature are
now available at six locations in the United States
and the Canal Zone. .

Costs and benefits of operational ERS systems

A 3-yr study to develop information about the eco-
nomic, social, and environmental benefits of an ERS
satellite system was completed. The study was con-
ducted under an EROS contract by the Earth Satel-
lite Corporation (1974) ; the firm of Booz, Allen, and
Hamilton served as subcontractor. Principal empha—
sis was placed on a benefit-cost analysis of three ERS
systems postulated for the 10-yr period 1977—86: an
aircraft system, a one-satellite system, and a two-
satellite system. Ranges were developed for both the
costs and the benefits of each system. For each al—
ternative, the benefit-cost ratio was less than 1 for
the low ranges and greater than 1 for the high
ranges. Many of the diverse benefits recognized, in-
cluding significant social, educational, and environ-
mental benefits, could not be quantified, although
such benefits may be substantial. The clear implica-
tion is that the computed benefits are conservative
and that additional experience, research, and analy—
ses are needed to evaluate the net value of future
operational ERS systems.

 

ADVANCED TECHNIQUES

ERTS—l, A New Window on Our Planet

An EROS-sponsored compilation of brief reports
relevant to the missions of the Bureaus of the De-
partment of the Interior was prepared by scientists
active in research with imagery and (or) DCP infor-
mation from the first Earth Resources Technology
Satellite (ERTS—l, renamed LANDSAT—1). The 85
different reports (USGS Professional Paper 929)
represent documented examples of scientific and
operational applications of ERTS—l data to certain
types of geologic, hydrologic, cartographic, biologi-
cal, and other environmental studies and programs.

Oil-slick detection with LANDSAT data

Morris Deutsch (USGS), in collaboration with
Alan Strong (NOAA), determined that major oil
slicks on marine water can be detected by LAND-
SAT. By employing optical techniques for process-
ing MSS data, it was possible to separate and color
code (1) oil floating on coastal waters, (2) water not
covered by oil, and (3) submerged features such as
shallow reefs and kelp beds. Optical enhancements
were prepared for apparent oil slicks on the Gulf of
Suez, the Mediterranean Sea, and the Atlantic Ocean
near Assateague Island, Va.

Linear features of the conterminous United States

Studies of the linear and curvilinear features
identified on the LANDSAT mosaic of the contermin-
ous United States (1:1,000,000 scale) by B. K. Luc-
chitta, G. G. Schaber, and W. D. Carter continued.
Selected areas were enlarged to scales of 1:250,000
and compared with geologic maps of the same areas.
Although the maps showed considerably more detail,
there was a high correlation between major features
identified on the mosaics and those shown on the
maps. There were other features identified on the
mosaics that did not correlate with mapped features
and are yet to be explained. These anomalous areas
will be compared with geophysical information where
it exists. Where such information is lacking, anoma-
lies may suggest areas where future geophysical
studies should be undertaken. E. H. Lathram com-
piled information for the western third of the United

237

238

States as part of the Circum-Pacific Cooperative Map-
ping Program, using the interpretations described
above as a base for the conterminous United States.

WESTERN REGION

Remote-sensing techniques aid agriculture

W. A. Lidster (Bureau of Reclamation) reported
that satellite data may benefit irrigators in the arid
West by providing an early warning system to detect
potential seepage problems on irrigated lands. Stud-
ies being conducted by the Remote Sensing Institute
of South Dakota State University with EROS funds
are showing significant correlation between water-
table depth and remotely sensed data. A multiple-
regression analysis utilizing aircraft and LAND-
SAT—1 data resulted in a 91-percent-co-rrect classifi-
cation of water-table—dep-th occurrence (greater than
or less than 2 m). These results indicate that LAND-
SAT data may provide reliable indications of water-
table depth; thus, some optimism is warranted for
using this technology in developing an early warning
system for detection of water tables approaching
2 m. Such a system would provide sufficient lead time
to design protective drainage works without loss of
crop production due to a high water table.

Remote sensing of Elephant Butte-Fort Quitman proiect

The Remote Sensing Center at Texas A&M Uni-
versity, under an EROS-funded contract from the
Bureau of Reclamation, carried out research on the
use of remote—sensing data from LANDSAT in the
management of irrigation projects. The Elephant
Butte-Fort Quitman project along the Rio Grande
River was used as a study site. Initial work was done
in developing a data base of satellite images that
provide agricultural and mineral-resource informa-
tion. Through various interpretive and analytical
techniques, information was derived that can be
utilized in the formulation of a regional development
plan. Darrell Mach (Bureau of Reclamation) coordi-
nated the efforts of the university with the ongoing
Rio Grande Regional Environmental Project.

Space data aid lineament analysis

Paul Merifield and Donald Lamar (California
Earth Science Corporation) continued their contract
study of lineaments on LANDSAT and Skylab
images and the relation of these lineaments to fault
tectonics and earthquake hazards in southern Cali—
fornia. They reported that northeastern, northern,
and northwestern lineaments on the images com—
monly coincide with known faults and that some

 

GEOLOGICAL SURVEY RESEARCH 1975

represent previously unmapped faults. One, the
Thing Valley fault, seems to be offset right laterally
between 700 and 1,300 m by the Elsinore fault.
Northeastern and west-northwestern faults are

. truncated by major northwest-trending faults and

seem restricted to basement terrane. Spectral stud—
ies in the Mojave Desert using band-ratio techniques
showed a general correlation between spectral levels
and the age and elevation of alluvial surfaces.

LANDSAT data useful in range management

E. L. Maxwell and G. R. Johnson (Colorado State
Univ.) (1974) studied the usefulness of LANDSAT
and other remote-sensing systems as rangeland man-
agement tools. A field measurement program sup-
ported and verified the successful use of LANDSAT
imagery for computer classification of vegetation
type, range condition, and green biomass. Biomass
classification was accomplished on three successive
LANDSAT images without retraining the computer;
this achievement indicates that biomass classifica-
tion may be less critical than expected. Extensive
statistical analysis of LANDSAT data has shown
that the MSS band 5 and the ratio of band 7 to band
5 are the most significant data for vegetation type
and biomass classifications. Cross-classification re-
sults of vegetation type and biomass provide a basis
for summarizing biomass availability by specie-s
group and by the area covered by each group. A
256,000-ha region was automatically classified for
less than $500, this accomplishment suggesting that
satellite imagery is a feasible range-management
tool.

Spatial precipitation estimation using space data

P. A. Davis and S. M. Serebreny (Stanford Re-
search Institute) (1974) analyzed polar-orbiting-

‘satellite data in developing and testing a technique

for estimating spatial precipitation over the moun-
tainous terrane of northwestern Montana. The study
was supported Jointly by the USGS, the Bonneville
POWer Administration, and the US. Army Corps of
Engineers. Cloud patterns, classified on visible or
infrared images, were used to characterize circula-
tion and saturation over time and space. Tests of the
precipitation estimation technique showed excellent
results for the April-June period and a moderate
underestimate for the October-December period. The
same cloud category for a given basin in different
seasons tended to occur with approximately the same
probable basin precipitation. Temporal changes in
the measurements of snow extent over a given basin

REMOTE SENSING AND ADVANCED TECHNIQUES

varied in the same manner as the measurements of
snow depth and water content. The fact that spatial
differences between the snow extent in two basins
did not correspond to the differences between snow
depth and water content suggested a significant vari—
ation in terrane influence on precipitation.

Tectonic and resource significance of geostructures

E. H. Lathram, assisted by N. R. D. Albert and
R. G. Raynolds, continued his study of the giant
(>1,000 km) linears seen for the first time on Nim-
bus images and LANDSAT mosaics of Alaska and
the Western United States. The study concentrated
on characterizing major geologic differences on op-
posite sides of selected linears in order to identify
the giant linears that have significantly influenced
the tectonic developments of large parts of Alaska
and may have influenced the movement of mineraliz-
ing solutions and consequently the localization of
mineralized areas. Three major, nearly orthogonal
sets of such linears have been recognized; many of
the giant linears separateareas showing significant-
ly different geologic or tectonic histories (Lathram
and Albert, unpub. data, 1975).

Pacific Northwest demonstration project

In response to the request of resource-agency per-
sonnel of the Pacific Northwest States and the Land
Resource Inventory Task Force of the Pacific North-
west Regional Commission for recommendations on
the use of remote sensing in State resource inventory
and management problems, the EROS program and
Ames Research Center (NASA) suggested the estab-
lishment of a Pacific Northwest demonstration proj-
ect. The project, which was approved by the Gov-
ernors of Idaho, Oregon, and Washington in October
1974, was entered into jointly by the Commission, the
Department of the Interior, and NASA. Land-
resource analyses and inventories of selected areas
are being conducted at Ames Research Center by
employees of the Pacific Northwest States, who re-
ceive support, assistance, and guidance from USGS
and NASA resource and technology specialists and
use both satellite and high-altitude—aircraft data
provided by EROS and NASA. The goal of the proj-
ect is to equip State resource-agency personnel with
the knowledge and skills necessary to utilize the
synoptic, multispectral, multitemporal, and digital
characteristics of LANDSAT data and thereby pro-
vide the information required to formulate appropri-
ate and effective management decisions. Problem
areas for initial studies have been identified by 28

I

 

239

participating State agencies, a number of workshops
have been held, and specialists from the EROS Data
Center, the USGS Geography Pro-gram, and NASA/
Ames have been working with State personnel.

Resource inventory for the Crow and Northern Cheyenne Indian
Reservations

The Raytheon Company (1975), under an EROS-
funded Bureau of Indian Affairs contract, made a
study of the comparative usefulness of LANDSAT
data and aerial photographic data in taking a re-
source inventory on the Crow and Northern Chey-
enne Indian Reservations. LANDSAT was found
useful for collecting broad-area data on forest stand
distribution, surface and subsurface hydrology, land
use, and landforms. The cost savings projected for
the use of LANDSAT data were substantial in com-
parison with the cost of generating information of
equal detail from the aircraft images.

CENTRAL REGION

Estimates of center-pivot irrigation systems from LANDSAT
images

Center-pivot irrigation systems are readily ob-
served on LANDSAT images, particularly on band 5
(600 to 700 nm), where the contrast between irri-
gated and nonirrigated areas is marked. In recent
years, deployment of center pivots has increased
rapidly; Nebraska, for example, is currently adding
about 2,000/yr. In some areas, the increased deploy-
ment could affect the local water table. Both the
University of Nebraska and the EROS program used
LANDSAT images experimentally to count the num-
ber of center pivots in use during the irrigation sea-
son. The number of center pivots in part of Holt
County, Nebr., for example, increased from 508 in
July 1972 to 555 in July 1973 and 740 in August 1974.

Wetlands inventory using LANDSAT data

The Remote Sensing Institute of South Dakota
State University (R. G. Best, D. G. Moore, and
Robert Lindler (South Dakota State Univ.), 1974)
employed LAN DSAT data to inventory the wetlands
of Codington County, S. Dak. The locations, spatial
distributions, areal extents, and vegetative cover
types were determined for the county, which is typi-
cal of the Prairie Potholes region of the northern
Great Plains. Change-s in the number of wetlands and
their areas were determined between April 25, 1973,
and October 4, 1973. The investigation indicated that
LANDSAT data can be used to measure the effects
of land changes on wildlife.

240

Analyses were made by optical processing tech-
niques in which enlargements of the original images
to scales as great as 1:60,000 were prepared. At this
scale, recognition of open-water wetlands by photo-
interpretation was effective for areas as small as
stockponds for certain landscapes. Vegetation classi-
fication and recognition of vegetation-filled wetlands
were limited to areas of approximately 4 ha or larger.
A light snow cover on the landscape made it easier
to interpret and map the occurrence of emergent
vegetation within wetlands. Areas larger than 24 ha
were measured with errors of less than 10 percent
with an inexpensive compensating planimeter.

LANDSAT imagery aids ground-water exploration

G. K. Moore and Morris Deutsch (1975) investi-
gated applications of LANDSAT imagery to ground-
water investigations. The imagery oifers an oppor-
tunity to apply satellite data to nationwide water-
resource studies, since it can be used both as a tool
and as a form of basic data. Its main advantage is its
reduction of the need for field work. Broad regional
features, which are difficult or impossible to see on
the ground, can be seen easily on LANDSAT images.
Some present and potential uses indicated from ex-
aminations of satellite data are as follows: (1) Loca-
tion of ground water indicated by phreatophytes
growing along the Rio Grande River east of Los
Alamos; (2) delineation of areas of recharge by
means of playas in the southern High Plains of
Texas; (3) improvement of aquifer development and
management by delineating urban sprawl and growth
in the Chicago area; (4) improved delineation of
landforms and geologic structures in Missouri, New
York, and Pennsylvania; and (5) delineation of
water—bearing faults and joints in Tennessee.

LANDSAT data useful for surface‘water mapping

The Remote Sensing Institute of South Dakota
State University developed optical processing tech-
niques for enhancing LANDSAT data as a source of
surface-water information, including areal extent
and the presence of suspended sediments, algae, and
emergent vegetation (D. G. Moore, M. E. Wehde, and
V. I. Myers (South Dakota State Univ.), 1974).
Black-and-white prints of the several MSS bands
were differentially exposed to depict contrasting
tones in water and comparatively interpreted by
using both multispectral and temporal approaches.
Enlargements were registered to USGS topographic
maps at scales as large as 1:62,500, and lakes as
small as 2.4 ha were planimetered. For color com-
posites of multispectral data from LANDSAT, bands

 

GEOLOGICAL SURVEY RESEARCH 1975

4, 5, and 6, instead of the customary combination of
bands 4, 5, and 7, were used to produce maximum
contrast within the water. MSS band 7 provides the
greatest contrast for locating surface-water bound—
aries but yields relatively little information on water
characteristics.

EASTERN REGION
Flood mapping from space

Morris Deutsch and F. H. Ruggles, Jr. (USGS) , to-
gether with George Rabchevsky (Photo Science,
Inc.) (Deutsch, Ruggles, and Rabchevsky, 1974;
Deutsch and Ruggles, 1974), analyzed LANDSAT
data covering the floods that occurred during 1973 on
the Mississippi and Connecticut Rivers in the United
States and the Indus River in Pakistan. They deter-
mined that areas in flood can be quantitatively deter-
mined by optical data—processing techniques. They
also observed that the effects of flooding on the re-
flectance characteristics of the surface make it possi-
ble to delineate areas from which floodwaters have
receded by using postflood data; this procedure
eliminates the necessity for (1) continuous tracking
with images of the flood crest and (2) reduction of
the volume of data required. Interpretations of flood
conditions as well as delineation of floodwater bound-
aries were made from color composites of MSS
near-infrared bands 6 and 7. A flood wave of July
1973 on the Connecticut River was projected onto a
1124,000-sca1e USGS topographic map by using an
MSS band-7 image. The flood boundary was accurate-
ly delineated, as determined by-field checks and com-
parison with conventionally acquired data. For the
Indus River flood, spectrally enhanced images were
used not only to delineate flooded area but also to
reveal areas of ponded water, leakage under a dam,
canal breaks, regional hydrologic conditions, and
flood-plain details.

FOREIGN AREAS

Remote sensing in Iceland

During a long-term, binational, multidisciplinary
remote-sensing research project conducted by the
USGS and various Icelandic scientific organizations,
LANDSAT imagery in particular, as well as NOAA
imagery, color and color-infrared aerial photography,
and aerial thermography (thermal infrared image-
ry), was used to study various dynamic environ-
mental phenomena of Iceland; primary emphasis
was placed on Icelandic geothermal areas, volcanoes,
glaciers, and rangeland areas (R. S. Williams, Jr.,
and others, 1973a, b).

REMOTE SENSING AND ADVANCED TECHNIQUES

Of particular scientific importance was the study
of the area encompassed by Icelandic glaciers and
icecaps. Initial analysis of the available LANDSAT-
1 images has shown the importance of repetitive
imagery for:

1. Recording relatively short term glaciological
changes. According to measurements made on
two LANDSAT—1 images taken 11 mo apart,
an outlet glacier in the northeastern part of
Vat'najokull surged 1.8 km. A combination of
field observations and LANDSAT image analy-
sis showed a total surge in excess of 3 km,
which probably took place in a few months,
perhaps in as little as a few weeks. Contorted
moraines on another of Vatnajokull’s outlet
glaciers, Skeidararjokull, on the southeastern
coast, showed a movement of 600 m in 11 m0,
even though the snout of the glacier remained
in essentially the same position.

Several glacier-margin lakes were observed
to change in size during the year (1972—73),
particularly Graenalén, which enlarged each
time that it was imaged until its size dimin-
ished markedly after a jokulhlaup partially
emptied the lake in August 1973. Seasonal
changes in the size of sediment plumes along
the coast, where glacial rivers debouch their
sediment-laden water into the ocean, were
observed in a time-lapse manner (Williams and
others, 1974).

2. Furnishing the data necessary to reViSe certain
glaciological features on maps and to produce
orthoimage maps of icecaps directly from
LANDSAT images at map scales of 1:250,000.
Sufficient LANDSAT images of Iceland from
the late summer and early fall of 1973 now
exist to planimetrically map accurately the 90
percent of Iceland that is covered by glacial ice.
The best possible images (minimum snow cov-
er, maximum exposure‘ of glacial ice) have
been obtained of Vatnajokull, Langjékull,
Hofsjokull, Myrdalsjokull, and Eyjafjallajo-
kull, or five of the seven largest icecaps in Ice-
land and five of the smaller (less than 50 kma)
icecaps as well. On August 19, 1973, Hofsjokull
had an area of 915 km2 on LANDSAT image-s.
Its area has usually been cited as 996 kmz. On a
1945 Danish Geodetic Institute map (1 :500,000
scale), the area is 981 kmz; 1969 US. Army
maps (1:250,000 scale) show an area of 943
km? (Williams and others, 1975).

3. Mapping subglacial volcanic and structural fea-
tures. Within or at the margins of the icecaps

 

241

and outlet glaciers, a number of new glaciologi-
cal, structural, and volcanic features can be
mapped from LANDSAT—1 images, particular-
ly at low solar illumination angles (<10°);
these features include several probable sub-
glacial central volcanoes, calderas, and tectonic
lineaments. Some of the effects of j 6kulhlaups
can be mapped, including subsidence cauldrons
resulting from subglacial volcanic activity or
intense geothermal activity (R. S. Williams,
J r., and Sigurdur Thorarinsson, 1973; Thorar-
insson and others, 1973; Williams and others,
1973c).

LANDSAT imagery aids hydrogeologic mapping in North Yemen

LANDSAT imagery was selected to support a
study of the hydrogeology of North Yemen. Optical
enhancements of the images reveal details of alluvial
fans and coastal plain sediments that will signifi-
cantly reduce the time needed for field observations
and improve hydrogeologic mapping accuracy. Struc-
tural controls on the movement of ground water
were readily observe-d by M. J. Grolier and Morris
Deutsch. Whereas sand dunes in the northeastern
part of the country could not be delineated on unen-
hanced LANDSAT images, the enhanced images re-
vealed the dune distribution in detail and, in some
areas, the distribution of subdunal bedrock.

Applications of LANDSAT data to land-system mapping in
Australia

C. J. Robinove, working with coinvestigators in
Queensland, Australia, studied the application of
LANDSAT data to land-system mapping, a unique
Australian approach to describing and mapping land
capability, primarily for agricultural purposes. Digi—
tal computer analysis of LANDSAT-image magnetic
tapes is a promising tool for classifying and mapping
land systems and may supplement to a great degree
normal photointerpretation and field-mapping
procedures.

Ground-water exploration in Kenya

Morris Deutsch (1975) assessed the potential of
remote-sensing techniques for ground-water explora-
tion along the Tana River in Kenya. Anomalous vege-
tation distribution resulting from the presence of
shallow ground water in an otherwise semiarid re-
gion was readily observed on low-altitude color-in-
frared images. Emitted radiation measurements
taken from the low-flying aircraft with a precision
radiation thermometer showed an inverse relation-

242

ship between infrared transmittance of vegetation
and the radiometric temperatures.

Application of LANDSAT data to mineral exploration in
South America

A followup experiment to evaluate ‘LAN‘DSAT
multispectral imagery as a tool in exploring for
mineral resources in the Andes Mountains of South
America was conducted by W. D. Carter in coopera-
tion with geologists from Peru, Bolivia, Chile, and
Argentina. Emphasis was placed on the use of sea-
sonal data to determine how time-variant phenomena
(sun angle, soil moisture, snow distribution, vegeta-
tion) aid or hamper the recognition of areas where
mineral resources are likely to occur. The association
of prominent linear features with the distribution of
known deposits and mapped fault zones was estab-
lished by earlier work. CCT’s from the LANDSAT
MSS system were analyzed on an interactive com-
puter analysis system. Reflectance signatures .for
known rock outcrop areas (the copper-bearing Totora
Formation and freshwater limestone) have been ex-
tended throughout a scene covering 34,225 kmz.
Future work of this type will attempt to develop
signatures for alteration zones associated with major
porphyry copper deposits of northern Chile and to
subdivide the salt deposits of major salars such as
Uyuni and Coipasa in Bolivia.

REMOTE-SENSING EXPERIMENTS BY OTHER
BUREAUS

The EROS program continued to support investi—
gations conducted by other Bureaus to assess the
utility of remote sensing in resource inventory. A
summary of the progress of these experiments
follows.

Monitoring weather parameters for the High Plains Cooperative
Program

A. M. Kahan (Bureau of Reclamation) developed
and tested an automatic system, using LANDSAT
DCS capabilities, for the collection of precipitation
and meteorological parameters from the Bureau’s
High Plains Cooperative Program cloud-seeding site
near Miles City, Mont. The design incorpbrates a
network of digital precipitation gages, developed as
a part of this program, operating within a 19-km
radius of a LANDSAT DCP station. The design also
includes a concept for data collection by aircraft
from a network of gages operating over an area of
several thousand square kilometres. These prototype

 

GEOLOGICAL SURVEY RESEARCH 1975

networks were installed near Miles City for the sum-
mer operating season.

Colorado River natural-resource and land-use data acquisition

R. L. Hansen (Bureau of Reclamation) worked
with the University of California at Berkeley to
transfer the university’s computer software systems
to the computer system at the Bureau’s Engineering
and Research Center in Denver, Colo. Bureau per-
sonnel were assisted in making the necessary modifi-
cations to the software. Trained Bureau personnel
will do complete analyses of LANDSAT images from
CCT’s for agricultural inventory as it relates to use
of irrigation water. Cooperative efforts with the uni-
versity will continue through calendar year 1976 to
fully develop the Bureau’s in-house capability for
digital analysis of remotesensing data, not only for
agricultural inventory but‘also for a variety of natur-
al resources. This technology should lead to better
development and management techniques for water
resources in the arid West.

Use of LANDSAT data in fishery management

J. B. Reynolds (US. Fish and Wildlife Service)
utilized LANDSAT imagery as a resource manage-
ment tool for solving fishery management problems
in Midwestern States. Methodologies for conducting
inventories of small impoundments were developed
through the use of LANDSAT imagery and ground-
truth data provided by an interagency working for-
um composed of investigators from eight States.
Accurate inventories of small impoundments are re-
quired for the allocation of fishery management
efforts, extension activities, and distribution of
hatchery fish.

Comparative analyses were made of inventory in-
formation previously gathered by the States and
information derived from LANDSAT and aircraft
imagery. Reynolds feels that computer analysis of
LANDSAT images will provide more rapid inven-
tories of key areas within the Midwestern States.

LUMINESCENCE STUDIES

The Fraunhofer line discriminator (FLD) is an
electro-optical device that operates as a nonimaging
radiometer and permits detection of solar-stimulated
luminescence several orders of magnitude below the
intensity detectable by the human eye. R. D. Watson
and W. R. Hemphill reported that airborne tests of
the FLD permitted measurement of significant dif-
ferences in the luminescence of trees growing in soils
containing geoohemically high concentrations of cop-

REMOTE SENSING AND ADVANCED TECHNIQUES

per (near Denver, Colo.) and molybdenum (near
Reno, Nev.) and that of trees growing in background
areas nearby. In other airborne tests, the FLD dis-
tinguished luminescing phosphate rock from gypsum
and barren sandstone near Pine Mountain, Calif;
dispersal of oil in a natural seep from uncontami-
nated seawater in the Santa Barbara Channel in
California; sewage effluents near Denver; and paper-
mill and phosphate-processing efliuents in eastern
and central Florida.

Supporting measurements made by using a fluores-
cence spectrometer demonstrated the technique of

predicting in the laboratory the optimum FLD wave—‘
length required to detect the luminescence of a ma- I

terial prior to mounting an airborne test. Lumines—
cence spectra were measured for each material and
corrected for wavelength variation in source and de-
tector sensitivity, and the results were compared to
the luminescence of a dilute standard solution of
rhodamine WT dye. The luminescence of each ma-
terial was then related to the FLD, which has a
sensitivity of 0.25 ppb rhodamine WT dye in 1/2 m of
water. The optimum Fraunhofer wavelength for
detecting metal-stressed vegetation with an FLD
was found to be 656.3 nm; for each of the other ma-
terials, the wavelength was 486.1 nm.

Results of theSe laboratory measurements are as
follows:

Luminescence
expressed as

rhodammc
equivalent
WT dye con-
centra-
Material tion (ppb)
Oil seep _______________________________________ 4.0
Metal-stressed vegetation ________________________ 0.3—0.7
Phosphate rock ________________ ‘ _________________ 0.7
Phosphate-processing effluent _______-___-_'_ _______ 0.8—2.4
Paper-mill efl‘luent ______________________________ 0.30—1 . 6

APPLICATIONS TO GEOLOGIC STUDIES

The radiobrightness of moist or frozen soil

The radiobrightness of soil is profoundly affected
by the amount and state of included liquid water
because the relative permittivity and loss tangent of
liquid water are far greater than those of truly dry
rock or soil. If the included moisture is frozen, how-
ever, the bulk dielectric properties approach those of
the dry host material. A. W. England and G. R.
Johnson reported that this characteristic can be used
to remotely obtain the depth of a phase boundary
(either frozen soil over moist soil or moist soil over
frozen soil) from the spectral character of the radio-
brightness. That is, the energy at appropriately
short wavelengths originates Within the layer,

 

243

Whereas energy at relatively longer wavelengths
originates within both the layer and the underlying
half-space. The resulting variation with wavelength
of the radiometric temperature is interpretable in
terms of layer thickness. Theoretical models of the
effect are consistent with observations at 21 cm.

It is possible, therefore, to remotely sense a ther-
mal anomaly that affects the thickness of seasonally
frozen ground. It should also be possible to remotely
observe the rate of melting of an active layer over
permafrost and to infer moisture content.

Mineral-resource studies using LANDSA'I' images

A technique that combines digital computer proc-
essing and color compositing was developed by L. C.
Rowan and P. H. Wetlaufer (USGS), A. F. H. Goetz
and F. C. Billingsley (Jet Propulsion Laboratory),
and J. H. Stewart (USGS) (1974) for enhancing
subtle spectral reflectivity differences among exposed
rock and soil units. This technique has been used to
detect and map hydrothermally altered areas and to
distinguish among many rock types in a LANDSAT—
1 MSS image of a part of south-central Nevada. Field
evaluation shows that altered areas appear as anom-
alous color patterns on the color-ratio composite and
that these areas agree very closely with those map-
ped on the ground. Most of the distinctions realized
through this approach cannot be obtained by using
MSS color-infrared composite images or Skylab/
EREP color images.

Landform analysis using LANDSAT—l MSS
images and image mosaics of Nevada showed that
linear features compiled without respect to length
have approximately 25 percent coincidence with map-
ped faults. However, the major lineaments (> 10 km
in length) and the mapped faults have about 80 per—
cent coincidence, and substantial extension of locally
mapped faults is commonly indicated. Seven major
lineament systems identified by Rowan and Wetlauf-
er (1975) appear to be old zones of crustal weakness
that have served as preferred conduits for rising
magma through periodic reactivation. Reactivation
of these zones approximately 30 my ago led to mi-
gration of silicic volcanism from the central basin to
a crudely circular feature 150 km in diameter, the
central Nevada volcanic complex. The horizontal and
vertical extents of this feature are substantiated by
aeromagnetic, gravity, and seismic refraction data.
Known metal mining districts are concentrated along
five of these major lineament systems. However, the
central Nevada volcanic complex occupies an area of
low productivity, which is probably due to burial of

244

older deposits by a thick sequence of silicic volcanic
rocks deposited between 30 and 19 m.y. ago.

Lineaments in South Carolina and the Mississippi Embayment

In a LANDSAT study by T. W. Offield of the At-
lantic Coastal Plain of South Carolina, long, straight
drainage lines were the dominant lineaments; these
trend northwest, parallel to and commonly coinciding
with alinements transverse to the general trend in
the magnetic basement, and possibly mark the posi-
tions of Triassic dikes. All but 2 of 22 crudely located
historic epicenters in South Carolina lie along topo-
graphic drainage lineaments, and most are near
lineament intersections.

Lineaments mapped by D. W. O’Leary and S. G.
Simpson from LANDSAT images of the northern
Mississippi Embayrnent generally showed groupings
of several orthogonal sets, which varied somewhat in
trends and intensity of development from one geo-
morphic-tectonic province to another. The dominant
lineament group trends N. 40°—50° E. throughout
the region, regardless of local tectonic setting, only
slightly skew from the location of microearthquake
activity. A second major lineament trend, N. 40°—
50° W., approximates a subsidiary trend in the seis-
mic data.

Near-infrared reflectance anomalies of andesite and basalt

High-reflectivity anomalies in the near infrared
(1.0 to 2.6 pm) were observed by H. A. Pohn on scan—
ner images obtained by the Environmental Research
Institute of Michigan on flights over southern Cali-
fornia and southwestern Nevada and, more recently,
on all three Skylab missions. These anomalies almost
always occur in andesites or more mafic rocks.
Laboratory spectra obtained from the rocks collected
in the anomalous areas show that some rocks ex-
hibit the highest reflectivity from their natural sur-
faces, whereas others show a distinctly higher re-
flectivity from cut surfaces. In the last case, the
material (as yet unknown) giving rise to the anoma-
lous reflectivity seems to have been emplaced at the
same time that the host rocks were deposited and to
have been altered at the surface by weathering. If
this occurrence is common enough and if its cause
can be determined, the intensity of the anomaly
might be used as a relative age-dating factor for
volcanic materials.

Principal lineament systems seen in orbital images reflect
ancient major breaks in basement rocks

Lineaments, fractures, and faults mapped by D. P.
Elston at a 124,000 scale correlate with lineaments

 

GEOLOGICAL SURVEY RESEARCH 1975

and lineament systems mapped from orbital images.
The major lineament systems mapped for central
Arizona occur in sets of orthogonal pairs that closely
correspond to the principal directions of fracturing
and folding in Precambrian rocks of the Grand Can-
yon of northern Arizona. The principal lineament
systems trend northeast and north, can be traced
across parts of the Colorado Plateau in rocks that are
only a few million years old, and reflect throughgoing
fracture systems [in the Precambrian basement.
Paleomagnetic orientations of the principal fault and
lineament systems (1,700, 1,100, and 850 m.y. ago)
describe a general clockwise rotation through about
220° of arc. Senses of displacement on the fault sys-
tems as they rotated through time to the present
suggest that most compressive stresses originated
from a westerly (Pacific) direction and that most
normal faults stepped down to the east.

Detection of geothermal areas from Skylab thermal data

Skylab—4 S~192 X—5 thermal data from The Gey-
sers, Calif, area were analyzed by H. A. Pohn to
determine the feasibility of using midday Skylab
images to detect geothermal areas. The hot-test
ground areas indicated on the Skylab image corres-
ponded to south-facing barren or sparsely vegetated
slopes. Thermal well No. 4, a geothermal area ap-
proximately 15X30‘m, coincided With one of the hot-
test areas indicated by Skylab. However, this area
could not be unambiguously distinguished from the

. other areas, which are believed to be hotter than

their surroundings as a result of topography and
micrometeorological conditions. A simple modifica-
tion of a thermal model (Watson, 1971) was made,
and the predicted temperatures for the hottest slopes
were in good agreement with the observed data. It is
concluded that data from a single midday Skylab
pass cannot be used to locate geothermal areas.

Characterization of surface roughness in Death Valley, California

The conclusions of the Death Valley radar study
conducted by G. G. Schaber are summarized as
follows:

1. Small-scale roughness of natural sedimentary
surfaces can be distinguished and measured by
means of long-wavelength SLAR image data
obtained at high antenna depression angles.

2. The radii of curvature of surface irregularities
responsible for an observed breakpoint between
weak and strong diffused backscatter (within
the Rayleigh region of scatter) are restricted
to a size range of between 0.08 )t and 0.14 A. At

REMOTE SENSING AND ADVANCED TECHNIQUES

the 25-cm wavelength, the range is between 2
and 3.5 cm.

3. The breakpoint on the Rayleigh region of the
backseatter function can be predicted by using
a model of Rayleigh backseattering from an
array of spheres on a plane. A plot of the radar
cross section, normalized to the resolution ele-
ment area, shows that, at a radius of curvature
of 0:01 A, an inflection occurs in the curve. The
agreement of the theoretical model and the
field observations suggests that even single-
frequency SLAR systems, when properly cali-
brated for return power, can be useful tools for
geologic mapping.

4. Antenna depression angles restricted to between
45° and 90° appear to optimize the image data
for surface backscatter evaluation by provid-
ing more return power and by eliminating ex-
tensive radar shadowing effects.

APPLICATIONS TO HYDROLOGIC STUDIES

Remote sensing used successfully in two hydrologic studies in
Alabama

J. G. Newton, in cooperation with the Geological
Survey of Alabama, used photography, thermal
imagery, and radar as supportive tools for a variety
of water-resource investigations. There were two
significant results.

1. Color-infrared photography was the primary tool
used in locating one of the highest yielding
wells in Alabama. The well, which taps lime-
stone, is near Centreville, in an area where
previous test drilling failed to locate satisfac-
tory supplies. It has been pumped at a rate
exceeding 63 l/s, with a drawdown in water
level of less than 1 m. The well was located at
the intersection of a lineament and a line of
previously unmapped sinkholes. The lineament
was formed on sands and clays of Cretaceous
age that rest on limestone of Paleozoic age. It
extends more than 8 km from an area near the
limestone outcrop to an area in which large
springs discharge. The lineament is formed
largely by the afinement of surface drainage
and accompanying variations in vegetation. It
is parallel to the strike of Paleozoic strata and
probably reflects faulting or post-Cretaceous
solution of the underlying purer carbonate
strata (W. M. Warren and C. C. Wielchowsky,
1973).

 

245

2. Color-infrared and black—and-white-infrared pho-
tography were utilized in Shelby County to
define linear trends formed by active sinkhole
development. These trends defined areas most
prone to sinkhole development and the location
of one fault. The photography, used in con—
junction with photography taken in 1960, also
helped to determine the relationship between
collapses in an area of large water withdrawals
and construction. In one small area containing
33 recent collapses, 26 collapses (79 percent)
were located where timber had been removed
or were within 15 m of a highway, its drain,
and a gas pipeline.

Icing surveys along the TAPS corridor

LANDSAT images, high- and low-altitude aerial
photographs, thermal—infrared images from an air-
borne scanner, and photographs taken with a hand-
held camera from light aircraft were used by C. E.
Sloan to map the location and extent of icings along
the TAPS corridor. Large icings, also called “aufeis,”
occur in wide braided channels of major streams
along the route. Small-channel and hillside icings are
common in geologic terrane that has the capacity for
shallow ground-water storage. Both surface- and
ground-water sources feed and sustain the growth of
icings. Ground disturbance in permafrost terrane
tends to aggravate the icing problems. Icings, where
they overtop roads, may cause flooding and erosion
and impair traffic flow.

Determining lake depth on the Alaskan North Slope with SLAR

SLAR images of the North Slope of Alaska be-
tween Barrow and Harrison Bay, obtained by the
USGS Mohawk remote-sensing aircraft in April and
May 1974, were used to study the tundra lakes in
that region. According to W. J. Campbell, the SLAR
images indicate that the tundra lakes can be sep-
arated into two classes based on the strength of the
returns. Correlations between the areal patterns of
the returns, limited ground observations of lake
depths, and the information obtained from LAND-
SAT images strongly suggest that freshwater lakes
giving weak returns are completely frozen, whereas
lakes giving strong returns are not. Brackish lakes
also give weak returns even when they are not com-
pletely frozen, presumably because the brine present
in the lower portion of the ice cover limits the pene-
tration of x-band radiation into the ice. The physical
cause for the differences in radar backseatter has not
been determined. The ability to separate tundra

246

lakes rapidly and easily into two classes by using
SLAR images will be useful in many ways, including

the determination of the annual dependable water-

supply for a given lake.

Effect of dual-wavelength excitation on Raman scattering
intensities

Recent use of the anti-Stokes lines to examine hy-
drogen plasmas suggested the use of a dual-wave-
length excitation to enhance Raman signal intensi-
ties. Several calculations were made by M. C. Gold-
berg and J. R. Riter, Jr., who used known Raman
cross sections to investigate the limits of this effect
against a water background. Particular attention
was given to maintaining all variables at reasonable
values and examining the lower limits of the number
of scatterers in solution to determine detection sensi-
tivities for solutes in dilute aqueous solutions. The
dual-wavelength technique suffers from a large
amount of water signal, and the calculations indicate
that minimum detection levels are 1,000 mg/l for
solutes similar to the nitrate ion.

Remote-sensing techniques applied to hydrologic problems in
Florida

A. E. Coker and A. L. Higer (A. E. Coker,
A. L. Higer, R. H. Rogers, N. J. Shah, Lawrence
Reed; and Sylvia Walker, 1975) compared wave-
lengths from Skylab and LANDSAT scanners to
determine their adaptability to land—water classifica-
tion. The longer wavelength bands on Skylab’s 8—192
scanner were found to enhance land-water features.

A. L. Higer, A. E. Coker, and E. H. Cordes (1974)
reported that the USGS acquisition network using
LANDSAT data is a viable approach for obtaining
the near-real-time data needed to solve hydrologic
problems. Selected water-quantity and water-quality
data obtained from ground stations are transmitted
through LANDSAT to NASA receiving stations.
This data relay has been reliable, and, by coupling
ground information with LANDSAT images, a mod-
eling technique is available for water-resource man-
agement in southern Florida.

Land use and vegetation in the Green Swamp, Florida

Using Skylab MSS data, A. E. Coker categorized
the land-water cover types of the Green Swamp area
of central Florida. The categories are shown on a
color-coded computer-generated thematic map of the
swamp area.

The'Green Swamp, the fountainhead of five rivers,
is a broad, flat wetland comprising about 2,250 km2

 

GEOLOGICAL SURVEY RESEARCH 1975

of the central highlands of the Florida Peninsula.
The swamp was chosen as a Skylab/EREP test site;
data were from the June 13, 1973, NASA/Skylab
pass No. 10. A. E. Coker, A. L. Higer, R. H. Rogers,
N. J. Shah, Lawrence Reed, and Sylvia Walker
(1974) reported that automatic mapping with MSS
data produced a nine-category land-water cover map.

A map series report of land-water categories in
the Green Swamp was prepared by Coker, B. F.
McPherson, and Higer. The categories represent
selected vegetation composites and land-use prac-
tices and were derived by computer processing of
Skylab MSS data as part of a NASA/EREP study
of the area. A map that depicts wetlands and inter-

'mittently wet and well-drained uplands should be

helpful for estimating drainage conditions for land-
use planning in the Green Swamp area.

Remote sensing used in Minnesota water-resource investigations

To determine the usefulness of remote sensing in
water-resource investigations in Minnesota, G. F.
Lindholm and R. F. Norvitch evaluated Skylab,
LANDSAT, and NASA high-altitude images and
photographs in selected areas. Analyses include
image-enhancement techniques made possible by
using special equipment at the EROS Data Center
near Sioux Falls, S. Dak. Results indicate that photo-
graphs taken in the spring (May) are best for de
lineating areas of surficial sand. Sand areas are best
defined on LANDSAT color composites or Skylab
color-infrared photographs. The repetitive coverage
of LANDSAT demonstrates temporal changes in the
areal extent of the Snake River during the peak-
runoff period of 1973. The effects of changing
ground-water levels on features visible on high—alti-
tude photographs are not readily apparent on images
made in 1973 when both spring and fall recharge
were well below normal.

Image enhancement for hydrologic studies

Results of experiments conducted by G. K. Moore
showed that composite viewing of LANDSAT images
may enhance the determination of both the lithology
and the geologic structure in the southeastern United
States. In the first series of experiments, LANDSAT
images made during different seasons of the year
were reproduced on high-contrast film and combined
on a color—additive viewer. A sharp boundary (mark-
ing the edge of hydrologically significant thicknesses
of sand and gravel) along the Cretaceous and Paleo-
zoic contact in northwestern Alabama was defined by
differences in tone, texture, and drainage patterns.
None of . these factors is apparent on any single
LANDSAT scene.

REMOTE SENSING AND ADVANCED TECHNIQUES

In the second series of eXperiments, composite
viewing (with a mirror stereoscope) of LANDSAT
images made on different dates showed many more
lineaments than could be seen on any single LAND-
SAT scene.

LANDSAT images used to improve estimates of streamflow
characteristics

LANDSAT images were used by E. F. Hollyday to
discriminate the physiographic characteristics of
drainage basins in an effort to improve equations
used to estimate streamflow characteristic-s at un-
gaged sites.

Records of 20 gaged basins on the Delmarva Penin-
sula of Delaware, Maryland, and Virginia were
analyzed for 43 statistical characteristics of stream-
flow. Hollyday formulated multiple-regression equa-
tions that related these characteristics to basin
characteristics. Physiographic characteristics ob-
tained only from maps and images were used in a
control group of equations. Characteristics from
images were forest land, riparian vegetation, water,
and combined agricultural and urban land. These
characteristics were separated photographically by
using film-density-discrimination techniques. The
area of each characteristic in each basin was meas-
ured photometrically.

Comparison of control-group equations with ex-
perimental-group equations revealed that 15 out of
40 equations were improved (standard error of esti-'
mate reduced by more than 10 percent). For ex-
ample, the equation for the 5-yr-recurrence flood
peak was improved by 32 percent; the mean month-
ly streamflow equation for September was improved
by 25 percent; the 7-d 2-yr—recu‘rrence low-flow equa-
tion was improved by 20 percent; and the 3-d 2-yr-
recurrence flood-volume equation was improved by
60 percent. It was concluded that using data from
LANDSAT images can significantly improve the
equations, and therefore the estimates, for some
streamflow characteristics at ungaged sites on the
Delmarva Peninsula. The potential exists for im-
proving estimates in other physiographic regions.

Snow measurements from LANDSAT images

A snow-covered area was measured from LAND-
SAT images by M. F. Meier (USGS) and W. E.
Evans (Stanford Research Institute). Two mountain
massifs and 16 drainage basins were measured on
images made on many dates during two melt seasons.
It was determined that snow cover can be monitored

 

247

by using LANDSAT images—assuming that clouds
and a closed forest canopy do not interfere—and that
some satisfactory results are possible when only
single-band radiance slicing is used; however, more
precise determinations require two-band ratioing or
other more complicated pattern-recognition tech-
niques. Areal values in drainage basins can be used
to calculate the equivalent snowline altitude, which‘
has value for extrapolation to other nearby basins
that may be cloud covered or appear only partially on
images.

Applications of remote-sensing techniques to the study of
seasonal snow cover

Results of studies by M. F. Meier" (1973, 1974)
showed that the areal extent of snow can be meas-
ured by means of manual, optical, electronic, or digi-
tal techniques from data supplied by visible and‘near-
visible light sensors carried on Earth-resource and
meteorological satellites. These techniques cannot
routinely detect snow under clouds or a forest cano-
py. Active or passive microwave systems may permit
such detection over large areas, but the physics of
these possible techniques is not yet sufl‘iciently un-
derstood. The wetness or the temperature of a snow
surface can be measured by thermal-infrared radi-
ometers; wetness throughout a snowpack can be
measured by microwave radiometers. The electro-
magnetic scattering properties of snow have not been
defined.

APPLICATIONS TO CARTOGRAPHIC STUDIES

During fiscal year 1975, the Topographic Division
was‘funded by NASA and the EROS program of the -
Department of the Interior to investigate specific
cartographic application-s of space imagery and high-
altitude photography. The principal emphasis was
placed on data from LANDSAT—1 and LANDSAT—-
2, with secondary emphasis on Skylab missions SL—2
through SL—4.

LANDSAT investigations for cartographic appli-
cation began with the first LANDSAT launch in
1972, were augmented by data from the second
launch in early 1975, and resulted in recommenda-
tions to NASA concerning specifications for LAND-
SAT—C, scheduled for launch in 1977. Skylab was
launched early in fiscal year 1974, and experiments
continued with data from the S—190A, S—190B, and
S—192 sensors.

248

Satellite-image maps

Prototype image maps were prepared from LAND-
SAT and Skylab images at scales ranging from
1:125,000 to 1 : 1,000,000 and in standard and experi-
mental formats. Some maps were produced in several
versions—monochromatic, sepia tone, and multicolor,
with varying cartographic enhancement.

The Florida satellite-image mosaic is the product
of innovative procedures combining computational
photogrammetry, image geometric control, photo-
mechanical mosaicking, and color lithography. Flori-
da presented a new set of cartographic problems,
since it extends across seven LANDSAT orbits, two
basically different vegetation patterns, and two UTM
zones. The assembly of 17 images was controlled pho-
togrammetrically by using 27 points scaled from
1:24,000-sca.le topographic maps as ground control.
The mosaics were prepared by contact printing
through precise exposure Windows onto high-resolu-
tion stable-base film. The MSS band-5 mosaic was
used to prepare both the magenta and yellow plates,
and the MSS band-7 mosaic, the cyan plate. This
two-band three-color printing process yielded an
image that closely resembles the usual false-color
(infrared color film) rendition. A fitted UTM grid
(computed from ground control points) and the text
were overprinted in black. The accuracy of well-
defined points measured from the grid on the printed
map is estimated at 200 m. All the individual image-
format maps of Florida are being prepared as a by-
product of the mosaic; four covering southern Flori—
da at 1:500,000 scale are in press. Black-and—white
1:250,000-sca1e standard-format satellite-image m0-
saics are being prepared from the Florida band-5
mosaic.

The second version of the 1:500,000-scale satellite-
image map of Arizona was published. In contrast to
the first version, which was simply a black-and-white
gridded image mosaic, this map is a sepia-tone image
overprinted with blue water features and a black
UTM grid, selected culture, and text. A similar sepia
edition of the 1:250,000-sca1e Phoenix image map
also shows red roadfill.

Two black-and-white photomaps of the State of
Connecticut are being prepared, one from S—190A
panchromatic photographs formatted to the
1:250,000-scale Hartford topographic map and the
other from S—19OB color and color-infrared photo-
graphs formatted to the 1:125,000-scale Connecticut
State base map.

GEOLOGICAL SURVEY RESEARCH 1975

i Marking LANDSAT images with solar reflectors

On October 1, 1974, in collaboration with W. E.
Evans (Stanford Research Institute), the USGS suc-
ceeded in marking a LANDSAT—1 MSS image with
three mirrors positioned at the National Center in
Reston, Va. The mirrors—one slightly convex and
two plane—were oriented to reflect the Sun’s rays to
the satellite and thus generated cones of light of
05° (the angular diameter of the Sun as seen from
the Earth). The plane mirrors produced two bright
spots on the image, and the convex mirror produced
a less visible spot. The mirror flashes registered as
high radiometric response levels—2 to 5 times those
of adjacent pixels .(the smallest element recorded by
the scanner)—on the digital tape readout. After the
October experiment, various types of mirror support
and methods of pointing were tested. On November
24, LANDSAT—1 was flashed with a plane mirror
oriented by an autocollimation technique using a
Wild T2 theodolite and computer-generated data. As
before, the response in bands 4, 5, 6, and 7 reached
the saturation level for the mirror-site pixel.

This marking technique will have little carto-
graphic application in the United States (with the
possible exception of Alaska) because the country is
relatively well mapped, and suitable LANDSAT-
identifiable features can be described to an accuracy
better than the sensor pixel (about 79x79 m or 1
acre). In poorly mapped areas lacking identifiable
points, the technique does have cartographic poten-
tial for marking such features as offshore oil rigs,
small islands, or poorly defined points in Antarctica
or the Amazon Basin. If points are geodetically lo-
cated, they would then be located with respect to all
other features imaged by LANDSAT in the same
area, and thus the utility of the geodetic control
would be extended.

Digital processing of LANDSAT images

Mead Technology Laboratories (Dayton, Ohio),
under contract to USGS, is investigating the feasi-
bility of enhancing the photographic quality of
LANDSAT MSS images by digitally processing and
combining successive images of the same Earth
scene. CCT’s of MSS images from five passes over
Phoenix and five passes over upper Chesapeake Bay
are being digitally processed and correlated and con-
verted to hard copy for comparison with the hard
copy produced from a single MSS pass. If the quality
of LANDSAT imagery can be improved by digital
techniques, the scope of cartographic and other ap-
plications could be expanded. '

 

REMOTE SENSING AND ADVANCED TECHNIQUES

Cartographic evaluation of LANDSAT

From the mapping viewpoint, LANDSAT exceeded
expectations. The results of LANDSAT—1 carto-
graphic experiments, conducted by USGS and other
foreign and domestic mapping and charting agen-
cies, justified a resource satellite program that
should continue for a decade. The comprehensive
cartographic evaluation continued with the objective
of defining requirements and specifications for an
operational LANDSAT-type satellite based on world-
wide cartographic needs.

To date, the following applications of LANDSAT-
type imagery are considered feasible:

1. Serving as an image base for photomapping at
scales of 1:250,000 and smaller and in a variety
of formats.

2. Aeronautical charting, both for revision of gross
features on line charts and as an image base
for selective thematic mapping.

Mapping of shallow sea areas.

Extending control from mapped areas into and
across unmapped areas.

5. Identifying artificial points by marking images
with a small mirror.

Automated correlation to the figure of the Earth.

7. Revising gross features on line maps at scales of
1:250,000 and smaller.

8. Thematic mapping of water, infrared-reflective
vegetation, snow and ice, collective works of
man in some areas, and spatial changes in
these themes.

9. Precise delineations of waterlines at various
stages.

Future evaluations will be based on the develop-
ment of a variety of LANDSAT cartographic prod-
ucts and applications of various scales, waveband
treatments, formats, and processing techniques.
Product utility and potential economic value will be
determined through sales analysis and specific re-
sponse from those applying“ LANDSAT imagery
cartographically.

P99

9’

Specifications for LANDSAT—c

General requirements and specifications for
LANDSAT—C were recommended by the EROS pro-
gram on behalf of the Department of the Interior.
The recommendations, which were based on input
from most of the Department’s concerned user agen-
cies, Canadian and Australian mapping agencies, and
the World Bank, were evaluated and combined by the
EROS Cartography Coordinator. Further study was
suggested on such options as the wavelength of band

 

249

4, variable gain settings, and range of the thermal
channel.

APPLICATIONS TO GEOGRAPHIC STUDIES

Phoenix and southern Arizona land-use mapping project

The final report on the NASA—Sponsored test of
the utility of LANDSAT film imagery in updating a
land-use map of the Phoenix, Ariz., 1:250,000-scale
quadrangle, which had been previously compiled
from high-altitude aerial photographs, was com-
pleted and accepted by NASA (Place, 1974). This
investigation showed that the satellite color-compos-
ite transparencies could aid in the interpretation of
land use and complement the high-altitude aerial
photography in monitoring seasonal changes of
vegetation and water bodies.

Central Atlantic Regional Ecological Test Site (CARETS) project

The CARETS project, jointly sponsored by NASA
and the USGS, continued to analyze the usefulness of
remote sensors as sources of land-use and land-cover
data for input to a regional environmental informa—
tion system. This system is based on the flow of
land-use and related environmental data through
several stages, from acquisition by remote-sensing
techniques to users, and involves user evaluations
and feedback. The basic assumption of the CARETS
project is that there is a measurable environmental
impact associated with land use and land-use change
as determined with remote-sensor data, and, there-
fore, such data sets can be used to provide regional
planners and other users with an understanding of
the environmental changes occurring in their areas.

The CARETS research involves three interrelated
subtasks:

1. Land-use analysis: An analysis of the accuracy of
the CARETS land-use maps was completed for
a l-percent sample of the test-site area. Maps
using level II of the USGS land-use—land-cover
classification, produced at three scales
(1:24,000, 1:100,000, and 1:250,000) from
high—altitude aircraft photographs, were com-
pared with one another and with other data ob-
tained by field surveys. The same procedures
were employed to determine the accuracy of
the level I land-use maps produced at a
1:250,000 scale from high-altitude aircraft
photographs and LANDSAT images. By simple
comparison of point data samples from maps
with field-survey data, the accuracy of the

250

level II maps was determined to be 84.6 per-
cent at a 1:24,000 scale, 76.8 percent at
1: 100,000 scale, and 73.0 percent at a 1 :250,000
scale. Part of the difference in accuracy is at-
tributed to increasing generalization of data
when they are mapped at smaller scales. How-
ever, accuracy computations differ for different
major land-use categories, and a 'simple per-
centage calculation of the correspondence be-
tween sample points and field data is not con-
sidered tobe a fully adequate statement of
accuracy for land-use maps. The accuracy of
the level I 1:250,000-scale maps was 76.6 per-
cent from aircraft photographs and 71.8 per-
cent from LANDSAT images.

2. Environmental impact assessment: A series of
related investigations to evaluate and assess
the impact of land-use patterns and changes on
the environment continued. H. P. Guy and E. J.
Pluhowski experimented with using level I and
II land-use data derived from LANDSAT and
aerial photography sources to evaluate the ef—
fectiveness of CARETS land-use data in im-
proving estimates of streamflow characteristics
in selected Maryland drainage basins. Of 40
streamflow characteristics tested, 7 showed
more than 10 percent improvement (reduction
of the standard error) in prediction equations,
and 2 showed more than 10 percent impair-
ment in the predictions. Improvements were
posSible because of the information on the
amounts of urban, forest, and agricultural land
in the drainage basins.

J. E. Lewis, S. I. Outcalt, and R. W. Pease
investigated the usefulness of aerial and satel-
lite thermal imagery combined with land-use
data in simulating the urban climate. The most
recent research along these lines was an experi-
ment using thermal data from the Skylab
satellite as an input to an urban climate model.‘

A regional environmental study was con-
ducted for Virginia Beach, Va. It was deter-
mined that environmental problems such as
barrier-beach stabilization, beach replenish-
ment, and sewage disposal resulted from deci-
sions based on faulty knowledge of the coastal
and wetland ecosystems that are vital to the
city.

Further environmentally related research in-
volved the use of remote sensing to identify the
causes of manmade ground-water pollution.
Results indicate that certain remote-sensing

 

‘

GEOLOGICAL SURVEY RESEARCH 1975

data sets are useful in identifying land-use
types that have ground-water pollution poten-
tial associated with them.

3. User evaluation: The user interaction and evalua-
tion phase of the CARETS project was set up
to obtain the assistance of local, regional, State,
and Federal agency users of land-resource in-
formation in designing an experimental re-
gional information system. The evaluation re-
vealed that many user agencies at all levels of
government require data more detailed than
those provided by the CARETS project. Few
agencies found the generalized LANDSAT level
I land-use—land-cover maps useful. Although
the level II data were considered valuable by
several users, most found them to be of sec-
ondary utility to their needs. The products
considered most useful were the high-altitude
color-infrared photographs and the USGS
orthophotoquads.

The digitization of CARETS land-use—land-
cover data by the Canadian Geographic Infor-
mation System progressed in several stages.
The 1:250,000-scale level I land-use—land-cover
maps prepared from LANDSAT images were
digitized, and computer-printed land-use area
summaries, by county, were completed for the
entire CARETS area.

A separately funded research effort, con-
tained within the CARETS framework, was an
evaluation of the Skylab S—190B Earth terrain
camera. A 1:24,000-scale land-use map of Fair-
fax, Va., was produced from Skylab photo-
graphic data and compared with a 1:24,000-
scale field-corrected land-use map prepared
from high-altitude aircraft photographs. Both
maps utilized level III land-use categories. By
means of a point sampling technique, the rela-
tive accuracy of the Skylab map was deter-
mined to be approximately 83 percent.

Comparative urban studies

Another aspect of geographic applications research
and analysis dealt with comparative land-use studies
of a selected sample of U.S. urban areas using data
received from remote sensors aboard high-altitude
aircraft and satellites. Land-use maps and statistical
summaries were prepared by manual photographic
interpretation and area analysis techniques for Bos-
ton, Mass.; New Haven, Conn.; Cedar Rapids, Iowa;
Phoenix and Tucson, Ariz.; and Pontiac, Mich.

REMOTE SENSING AND ADVANCED TECHNIQUES

Products for all these demonstration areas (except
Boston and New Haven) included maps of land-use
changes for the period 1970—72, tabulations of land
areas and changes by land-use category, and census
tracts. Summaries by urban area for 1979—72 were
prepared for most of the test sites. Researchers ap-
plied observable land—use boundary segments equiva-
lent to the intent of the US. Bureau of the Census
urbanized-areas definition so that urban-area
changes in the intercensual period could be mon-
itored by remote—sensing techniques.

Land-use data acquired from Skylab images made
over some of these demonstration areas were com—
pared with data from aerial photographs and ground
surveys. Results of this comparison show that uses
of satellite imagery and (or) conventional sources of
data depend upon the aim and needs of the user.
Extensive briefings and discussion were held with
user groups to acquaint them with the applications
and limitations of the various experimental products.

Under a contract with the Association of American
Geographers, the USGS completed two tasks insup-
portive research in 1975. One of these was an analy-
sis of Washington, DC, land-use data derived from
airborne remote sensors in order to construct and
test an urban spatial model and to relate land-use
changes during 197 0—72 to an urban growth model.

The second task—the preparation of a guide to
assist users of remote-sensing data with land-use

 

251

mapping and inventory—resulted in the completion
of a publication (Wiedel and Kleckner, 1974) that is
essentially a description of analytical tasks and a1-
ternatives primarily in the use of airborne remote-
sensing data. The publication illustrates options in
the uses of these data and cites examples from vari-
ous Geography Program research projects.

Meanwhile, research continued in learning about
and applying ways to generate land-cover informa-
tion and to monitor land-use changes by direct com-
puter-aided interpretation of multitemporal and
multispectral data acquired from LANDSAT. One
applications thrust was to gather and analyze land-
cover information for comparative urban regional
studies, compare the data with information acquired
by conventional means, and assess general applica-
tions benefits and costs.

Another thrust sought to demonstrate specifically
the feasibility of using computer-processed satellite
data to complement inputs required for the USGS
Land-Use Data and Analysis (LUDA) program,
which is primarily dependent on manual compilation
from higher resolution sourCe materials. Results are
incomplete but are showing the capabilities and lim-
itations of the different approaches. This research,
therefore, suggests ways not only to exploit the com-
plementary features for the LUDA program but also
to identify other applications of monitoring data
acquired in digital form from satellite platforms.

LAND USE AND ENVIRONMENTAL IMPACT

RESOURCE AND LAND INVESTIGATIONS
PROGRAM

The RALI program established the following
short-term tasks to be implemented in fiscal year
1975:

1. Identify and assess the utility to the State and
local planning community of selected data and
information products (such as maps), systems
(such as geographic data systems), and
sources. This activity concentrated initially on
programs of the USGS and subsequently on
those of other Department of the Interior Bu—
reaus and Ofl‘ices. Its purpose is to develop the
ability to knowledgeably advise State and local
planners on the availability, sources, extent of
coverage, uses, and limitations of data.

2. Develop and disseminate information products,
including a series of directories of data hold-
ings and special information products of the
Department of the Interior.

3. Identify technical expertise in the Department
that is required by the regional, State, and
local planning community and develop pro-
cedures to make appropriate personnel avail-
able for consultation.

4. Continue to support and coordinate the prepara-
tion of methodological guidebooks that will im-
prove the state of the art in resource manage-
ment methods and techniques and further the
proper application of existing methods and
techniques in areas of interest to the
Department.

COUNCIL OF STATE GOVERNMENTS TASK FORCE

The National Symposium on Resource and Land
Information initiated a 1-yr study of State land-use
programs and policies by the Task Force on Natural
Resource and Land Use Information and Technology.
The symposium brought together approximately 200
persons representing the executive and legislative
branches of State government, Federal agencies, in-
terest groups, and other organizations.

252

 

The task force was sponsored by the Council of
State Governments under a grant from the RALI
program and in cooperation with the Office of Land
Use and Water Planning of the Department of the
Interior. A series of background papers on land-use
policy and program analysis was published in late
1974 and 1975 (Task Force on Natural Resources and
Land Use Information and Technology, 1974a—e,
1975a—c).

The task force report describes the difficulties in-
volved in land planning and management in terms
that permit better evaluation by political institu—
tions. The task force examined State experience and
evaluated the options available to States in establish-
ing or strengthening land-management programs. It
also reevaluated the Federal role in land manage-
ment and provided a State perspective for future
Federal legislation.

PRODUCT EVALUATION PROJECT

The purpose of this project was to design and
demonstrate a process of feedback between selected
State land and natural-resource data users and the
RALI program. Specifically, the aim was to have the
Council of State Governments, as an intermediary
third party, canvass State data users to determine
(1) how much use they can make of selected feder-
ally prepared data products, (2) what use they are
currently making of natural-resource data, and (3)
the best means for continuing a product evaluation
feedback mechanism that would facilitate communi-
cation between State users and Federal data
producers.

Samples of natural-resource data products con-
sidered by their producers to be new and innovative
were obtained from various Federal agencies; these
were largely map products. Criteria devised to evalu-
ate each product were presented as questions to users
in seven States. The States were chosen largely on
the basis of the States’ involvement in the particular
pro-gram areas.

The user responses to the particular products re-
viewed in this project and other results of discus-

LAND USE AND ENVIRONMENTAL IMPACT

sions with State program officials indicate, in some
areas, a significant consensus as to what is needed by
State data users. For example, among the most fre-
quently used or required items are USGS 71/2-min
topographic quadrangles, USDA Soil Conservation
Service detailed soil surveys, high-resolution aerial
photography, information on the location and quan-
tity of surface water and ground water, and recent
land-use—land-cover data.

ENVIRONMENTAL ASSESSMENT WITH APPLICATION
TO WESTERN COAL DEVELOPMENT

RALI has recognized the need for making a com-
prehensive analysis of the potential impacts associ-
ated with the development of Western coal resources
and in particular for making the information avail-
able in useful form to the planning community. Dur-
ing fiscal year 1975, RALI’s efforts to meet these
requirements have taken the form of two investiga—
tions, each of which has resulted in published
reports.

The purpose of the first study was to describe the
type of commercial activities that might be expected
in the development of Western coal reserves. Coal
mining is the primary activity and is likely to be
accompanied by the development of means to trans-
port coal from mining areas to centers of consump-
tion. Slurry pipelines and unit trains are examined
for the transportation of coal over significant dis-
tances. Alternatives considered to transporting coal
out of the region include the local conversion of coal
to synthetic fuels or electric power, the production
of substitute natural gas by coal gasification, and
the generation of power at the mine location. De-
scriptions of these alternatives are given by Anthony
Bisselle and others (1975) .

The second investigation was directed toward the
development of a systematic way to forecast “higher
order” impacts, as distinct from direct or “primary”
air, water, and land effects. Higher order impacts are
long-term consequences on the physical, social, and
economic conditions in a region, caused by repercus-
sions along the web formed by the network of cause
and effect events.

To determine the present state of the art and to
aid development of analytical methodology, an anno-
tated bibliography of techniques was prepared and
published by G. Bennington and others (1974).

The methodology developed in this research en-
tails combining a series of primary environmental
impacts expected as a result of future activities with
a matrix of environmental impact relationships. Each

 

253

term in this matrix relates a change in one cause in
one year to a change in effect the following year.
Thus, the forecasts for each of a set of environment-
al activities are produced that consider both direct
and higher order impacts.

This research is described by Benjamin Schlesing-
er and Douglas Daetz (1975) .

LAND-USE DATA AND ANALYSIS PROGRAM
AND OTHER GEOGRAPHIC STUDIES

The Land-Use Data and Analysis (LUDA) pro-
gram was initiated late in 1974 to provide a sys-
tematic and comprehensive collection and analysis of
land-use and land—cover data on a nationwide basis.
The initial nationwide collection of those data will be
completed within a 5-yr period. Periodc revision of
these data is planned.

LUDA maps are being compiled at a scale of ap-
proximately 1:125,000. For each land-use—land—cover
map produced, overlays are also compiled showing
Federal land ownership, hydrologic units, counties,
and census county subdivisions. State land owner-
ship is shown when such information is made avail-
able by the appropriate State agency. These overlays
are keyed to the standard topographic map series at
1:250,000 scale. By June 1975, 1,100,000 km2 of land-
use—land-cover data were compiled, and 128 quad-
rangles were in production. The compilation of these
map sets is being accomplished through regional
mapping centers of the Topographic Division with
specifications, quality control, and accuracy checks
to insure standardization and with consultation on
program development provided by the Geography
Program.

A series of tests was conducted by the Geography
Program to determine the most effective means of
assessing the accuracy of maps prepared under the
LUDA program. A combination of two methods
proved to be the most efl‘icient means. Low-altitude
aerial photography and ground-traverse data are
used to identify problem areas observed by inter-
preters as well as to provide a systematic check on
general interpretations throughout the map area.
Land—use—land—cover data are compiled at a scale of
1:125,000 and then reduced and keyed to the com-
bined black and blue color-separation plates of the
standard 1:250,000 topographic sheets. The mini-
mum mapping unit for urban and built-up uses, water
areas, confined feeding operations, other agricultural
land, and strip mines, quarries, and gravel pits is 4
ha. All other categories are delineated with a mini-

254

mum unit of 16 ha. Federal land holdings are shown
for tracts of 16 ha or larger.

Land-use and land-cover data are digitized in a
polygon format. Conversion of land-use polygonsto
land-use grid cells of varying sizes can be made when
desired.

There are three stages of release of maps and
data:

1. Maps are available on open file in USGS libraries
and may be reproduced upon request, at a nomi-
nal cost, on ozalid paper, ozalifoil, semistable
ozalid, cronar, or cronaflex materials. The
standard land-use—land-cover maps and accom-
panying overlays showing counties, hydrologic
units, Federal land ownership, and census coun-
ty subdivisions are available at a scale of
1:250,000. These products can also be obtained
upon request at scales within a reasonable
range of the compilation scale of approximately
1:125,000. For example, under a cooperative
agreement with the State of Florida, land-use-
land~cover maps were supplied at a scale of
1 : 126,720 to match the scale of county highway
maps in common use in that State.

2. Computer-generated maps and statistical data
are made available upon request about 6 mo
after lahd-use—land-cover maps and accompany-
ing overlays have been made available as indi-
cated above. Magnetic tapes are also available
for sale as well as documented software needed
for the use of the computer-generated data. Of
course, computer-generated maps can be sup—
plied at any scale compatible with the original
compilation scale of approximately 1:125,000.
It would be inappropriate, however, to use land-
use—land-cover data compiled at 1:125,000 for
preparing maps at scales such as 1:24,000,
1 : 50,000, or 1 : 1,000,000.

3. Lithographed maps are to be published in color.

Because of the dynamics of land use, the emphasis
in the preparation and distribution of all products
will be on supplying information to the users in the
shortest possible time. Applied research in data and
information requirements, inventory methods, and
data use, as well as interpretative studies, are also
being carried out under the LUDA program in order
to supply to State and Federal planners, resource
managers, and other users a basis for the most effi-
cient and effective use of these land-use—land-oover
data.

 

GEOLOGICAL SURVEY RESEARCH 1975

LUDA map and data uses in Louisiana

Louisiana was among the first States to be com-
pletely mapped under the nationwide LUDA mapping
program. Louisiana ofl‘icials promptly used these
data, along with satellite images of the State, to
determine how many hectares of various types of
land were inundated by spring floods during 1975.

A computerized analysis completed within 2 weeks
of peak flooding and 4 d after the last satellite pic-
ture was taken showed that 440,000 ha of Louisiana
were flooded at the highest stages on the Mississippi,
Red, Ouachita, Black, and Atchafalaya Rivers.

By comparing the LUDA land-use maps with flood-
time L'ANDSAT images, State officials determined
that floodwaters covered approximately 3,200 ha of
urban and other highly developed regions, 120,000 ha
of farmlands, 43,600 ha of upland forests, 279,200
ha of wetland forests, and 1,120 ha of sand and silt
deposits. Aided by the LUDA computerized data and
a computer program specialist from the Geography
Program, the Louisiana Office of State Planning staff
broke down these totals for each parish (county)
that had been flooded.

This effort marked the first time that land-use and
land-cover maps and data were used to give a State
Governor prompt, detailed information on how many
hectares of each land-use type, by county or other
area, had been affected by flooding.

Selected experimental LUDA demonstration proiects

In the State of Georgia, a land-use map of the
Atlantic metropolitan region was prepared at a scale
of 1:100,000 for use by the State Geologist’s Oflice.
The land-use map overlays the regional topographic
map at the same scale. The LUDA land-use—land-
cover information is used in conjunction with exist-
ing data such as those on mineral resources, soils,
seismicity, nuclear-reactor-site location, and ground
water ,already available to the State Geologist’s
Ofl‘ice.

Land-use maps at 1:24,000 were also produced for
selected portions of the 1: 100,000 map of the Atlanta
area. For planning and demonstration purposes, a
complete county and the entire Peachtree Creek
drainage area were mapped at this larger scale.

The Atlanta Regional Commission used these

' LUDA data for planning activities within the eight-

county region. The standard LUDA data were aug-
mented by information on urban parkland and insti-
tutional areas and a further breakdown of hydro-
logic units compiled by the commission.

LAND USE AND ENVIRONMENTAL IMPACT

Environmental impact uses of LUDA data

A land-use—land-cover map was prepared for the
region being studied by the Interagency Task Force
on Development of Phosphate Resources in South-
eastern Idaho. This 1:100,000-scale map enabled the
task force to relate environmental impact problems
to population distribution and other patterns of
human and natural resources. Large-scale land-use
maps were compiled for the Soda Springs area as an
aid in assessing the effect of increasing population
pressures on urban development and community
services. These maps will be included in the .final
environmental impact statement released by. the
task force.

Land-use—Iand-cover classification system

The land-use—land-cover classification system pro-
posed by the USGS after many meetings and consul-
tations with representatives of Federal and State
agencies is resource oriented. In developing such a
land-use—land—cover-.data system, several basic as-
sumptions, needs and requirements were recognized:

1. Recognition of existing, frequently used cate-
gories of land use and land cover. Sophisticated
but unfamiliar terminology was carefully
avoided, although a more refined or detailed ap-
proach to the classification of land use and
land cover might be more acceptable to those
seeking to institute a classification system that
relies more on logic than on practicality.

2. Flexibility in using the proposed approach to
standardization at the more generalized levels
of classification.

3. Application of an available and rapidly expanding
array of remote-sensor technology.

4. Recognition of the need for a means of quantify—
ing the use and character of land-use—land-
cover data on a consistent repetitive basis.

5. The assignment of a single use or cover designa-
tion to a given area so that a multiplicity of
uses could be handled by using the overlay
method rather than by using combinations of
use and cover categories.

The revision of USGS Circular 671 (J. R. Ander-
son, E. E. Hardy, J. T. Roach, and R. E. Witmer, in
press) will have “land cover” added to its title to
indicate more clearly the intermixing of land-use and
land-cover terminology in the classification system.
To some, this intermixture is undesirable. However,
a careful evaluation of alternatives led to the con-
clusion that unfamiliar or infrequently used terms
would be introduced if strict adherence to one ter-

 

255

minology or the other was observed. This approach
to land—use—land-cover mapping permits the aggre—
gation of level II categories into level I categories.
Even more important, it allows level III land-use—
land-cover categories to be added as desired by users.
Such categories would represent further subdivision
of the level II land-use—land-cover categories al-
ready compiled.

For example, under a cooperative agreement with
the State of Florida, land-use and land-cover data are
being compiled at level II. At the request of the
Florida State Department of Planning, an overlay of
selected level III categories-is being prepared. Some
of the level III categories being overlaid and fitted to
the level II categorization are (1) citrus groves
separated from other groves, nurseries, and so forth,
(2) mangrove swamps and cypress bogs separated
out of the level II “forested wetland” category, and
(3) mudflats separated out of nonforested wetland.

Cooperative land-use data proiects

A cooperative agreement between the Ozarks Re-
gional Commission and the USGS to provide land-
use—land-cover maps and data for portions of the
Ozarks'region was completed in 1974. During 1975,
amendments 1, 2, and 3 were completed. Work com-
pleted under the agreement was used as a basis for
the development of the LUDA program.

Amendment 1 extended land-use mapping and data
coverage to all areas of the State of Arkansas that
had not been previously covered. A complete land-
use—land-cover data base for Arkansas is now avail-
able in graphic format and with computer—assisted
analysis capability for land-use studies within the
State. The data base contains land-use information
delineated in compliance with level II land-use—land-
cover categories, political boundaries, public land
ownership, and drainage areas. The Arkansas High—
way Dep-artment used these data for highway corri-
dor planning.

Amendment 2 provided for compilation of addiz
tional data for those counties bordering the Arkan-
sas River from its junction with the Mississippi River
to Tulsa, Okla. These data consist of overlays keyed
to the standard 1:250,000-scale maps and show the
100-yr-old flood-plain outline, mineral deposits, utility
lines, surface transportation, fish and wildlife areas,
and historic sites. The Arkansas River Development
Corporation used these data in combination with a
previous study to determine land-use changes within
a selected area along the Arkansas River.

Amendment 3 provided for the digitizing of land-
use—land-cover data covering a four-county area in

256

central Arkansas. Data from a soils-capability map
were combined with the flood-plain, mineral-deposit,
and fish and wildlife data from the Arkansas River
project to provide nine levels of resource information
to be used in statistical data development for Faulk-
ner, Perry, Pulaski, and Saline Counties.

A final report, prepared jointly by the Ozarks Re-
gional Commission and the USGS Geography Pro~
gram, describing the research and experimental work
involved in the land-use—land-cover mapping and data
project was published and distributed by the Ozarks
Regional Commission at Little Rock, Ark. (Loelkes
and McCullough, 1975) .

Land-use maps and statistical data for Louisiana
were completed to fulfill a cooperative agreement be-
tween the State of Louisiana and the USGS. These
data include land use, land ownership (Federal and
State), river basins, State and county boundaries,
and census tract enumeration districts and were
mapped at a scale of 1:250,000. These data were also
digitized and already have been used for delineating
flooded areas during the spring of 1975. The land-
use—land-cover maps and data were supplied to the
Louisiana Office of State Planning at Baton Rouge to
complete the terms of this cooperative agreement.

Similar land-use maps were prepared at a scale of
1:50,000 for Lycoming County and the six counties
in the Pittsburgh, Pa., area (Allegheny, Armstrong,
Beaver, Butler, Washington, and Westmoreland
Counties).

Geographic information system development

The Geography Program carried out research and
development work on a geographic information sys-
tem to provide the capability for computer-aided
storage, editing, manipulation, and retrieval of a
geographic data base for the LUDA program and
other land-use—land-cover research projects of the
USGS. The system includes: (1) Digitization of maps
of land-use—land-cover and other environmental data,
(2) editing and updating of the geographic data base,
and (3) manipulation and retrieval of those data in
order to perform area measurements, map-composit-
ing analysis, and statistical and other computer-
aided operations.

Routine digitizing, editing, and correction of land-
use and land-cover overlays for all of the State of
Louisiana and part of the State of Florida were com—
pleted in cooperation with the Johns Hopkins Applied
Physics Laboratory and by using the Geography Pro-
gram’s Graphic Input Procedure (GIP). A prelimi-
nary version of documentation for the GIP was com~

 

GEOLOGICAL SURVEY RESEARCH 1975

plete-d and supplied to planning groups in Louisiana
and Florida for use in their own computer facilities.

Digitization of LUDA products with a laser scan-
ner began under a contract with the I/O Metrics
Corporation.

The procurement and implementation of the Ad-
vanced Interactive Digitization (DIGIT) system and
the CART/8 computer-aided map-compilation sys-
tem were completed in January 1975. These systems
are being utilized as an alternative procedure for the
operational digitizing, editing, and correction of land-
use and land-cover maps prepared for the LUDA
program and other Geography Program research
projects.

A grant made to the IGU’s Commission on Geo-
graphical Data Sensing and Processing for advice
and guidance on problems relating to the develop-
ment of a geographic information system in the
USGS was completed. The draft of the final report
included an examination of selected geographic in-
formation systems in the United States and Canada
and a description and analysis of five spatial-data
encoding techniques.

An additional grant to the IGU commission, con-
cluded in June 1975, for the review and analysis of
the LUDA/USGS data base development provided
for (1) determining the status of data base-structure
development in the USGS, (2) evaluating the ap-
plicability of existing software for computer-aided
spatial-data manipulation, data management, data
analysis, and computer-aided mapping and graphics,
and (3) analyzing CART/8 and the Information for
Management After Graphic Evaluation (IMAGE)
capabilities for use in the USGS Geography Program.

ENVIRONMENTAL IMPACT STUDIES

The Environmental Impact Analysis (EIA) pro-
gram was officially established within the Land In-
formation Analysis office on April 10, 1975. The EIA
program provides direction, coordination, and exper-
tise in the preparation of environmental impact
statements (EIS) for which the USGS is the lead or
joint agency and provides technical information and
expertise in support of the preparation of EIS’ to
which the USGS is only a contributor. The EIA pro-
gram provides technical analysis, review, and com-
ment on EIS’ prepared by other agencies and stimu-
lates, promotes, and conducts environmental research
related to the work and anticipated needs of the
program.

LAND USE AND ENVIRONMENTAL IMPACT

ANALYSIS OF ENVIRONMENTAL IMPACT
STATEMENTS

Some environmental research studies are involved
with analyzing the areas of environmental concern
and the problems of collecting, integrating, and pre-
senting environmental data. These analyses provide
the basis for guidebooks designed to assist the EIA
program, and other organizations with similar re-
sponsibilities, in the preparation and review of EIS’
and for suggesting topical investigations and re-
search needed to formulate and implement policies
for the USGS and the Department of the Interior.

During fiscal year 1975, the EIA program reviewed
approximately 2,100 EIS’ prepared by other agencies.
On the basis of a sampling of 1,400 EIS’, the subject
matter of these reviews breaks down approximately
as follows:

Subject of £15 Percentage

Road construction __________________________ 29
Hydrologic projects ________________________ 26
Airport construction _______________________ 10

Building construction ______________________ 8
National forest management ________________ 7
Nuclear power __________________ __ 4
Wilderness proposals _____________ _ I;
3
2
4

  

National park management _________________
Sewage-treatment facilities _________________
Utility-line installation _____________________
Others ____________________________________

Total _______________________________ W

Energy-related EIS’ account for 13 percent of the
reviews received but require 20 percent of the total
review time. EIS’ that are primarily concerned with
mineral resources account for 4 percent of both the
number of reviews received and the time required
for their processing. Because construction projects
make use of crushed rock, sand, and gravel, these
natural resources are of secondary concern in ap-
proximately 75 percent of the EIS’ reviewed.

On the basis of an analysis of these 1,400 EIS’
with geologic implications, 4 percent are considered
outstanding in that they present enough pertinent,
detailed geologic information to permit the reader to
make an independent evaluation of the impact of a
proposed action. Treatment of geologic elements is
more or less adequate in 56 percent of the statements

 

257

and clearly inadequate in 20 percent, which fail to
describe geologic conditions adequately enough to
support even a crude assessment of environmental
impact. Geology is ignored in 20 percent of the EIS’
reviewed. This analysis indicates a need for a greater
awareness of the significance of geology in planning
not only for the extraction of minerals or mineral
fuels but also for the emplacement of the many types
of engineering structures that produce major altera-
tions of the adjacent physical, economic, and cultural
environments. The EIA program is instigating
needed guidance in the form of technical assistance,
training sessions, and guidebooks for both govern-
mental organizations preparing EIS’ and private or-
ganizations assembling data required for an environ-
mental impact analysis.

ENVIRONMENTAL IMPACT RESEARCH

Other environmental research studies are con-
cerned with delineating the thresholds at which EIS’
are required, determining which aspects of the en-
vironment are important or critical to environmental
impacts, and evaluating techniques for analyzing the
potential impacts as well as monitoring the actual
impacts of various actions reported in EIS’ and
assessing them, especially in terms of land-use
decisionmaking.

W. J. Schneider, task force leader for the South-
eastern Idaho Phosphate Resources EIS, reported
that land-use maps of that area are being prepared
at compilation scales of 1:125,000 and 1:24,000 to
provide visual support for the EIS being prepared for
that area. Prestripping and current land-use patterns
are being delineated to provide a basis for assessing
the impact of stripping on land use. Continuing strip-
mining activity will be monitored by remote sensing
supported by ground checking, as required.

Ancillary research such as trace-element analysis
of slag, soil, water, and air contamination associated
with mining or ore processing is currently supported
by the Federal Interagency Task Force on South-
eastern Idaho Phosphate Resources.

INTERNATIONAL COOPERATION IN THE EARTH SCIENCES

With the development of new concepts and tech-
niques in the Earth sciences, the growth of scientific
capability in developing countries, and changes in the
US foreign assistance program, the emphasis of the
USGS’s continuing program of cooperation with
other countries changed from largely technical as-
sistance to cooperative research and scientific ex-
change. In the past, a large part of the work was
done under the auspices of the AID (Department of
State) and its predecessor agencies, whereas an in-
creasing number of projects are now sponsored by,
and funded by, the cooperating country or through
international organizations. AID continues to spon-
sor some selected projects of the USGS.

The USGS international program can be broken ;

down into four major categories: (1) Technical
assistance to strengthen Earth-resource institutions
and programs in developing countries; (2) scientific
and technical cooperation on subjects of mutual con-
cern; (3) participation in international commissions
and programs; and (4) response to natural disaster.

TECHNICAL ASSISTANCE AND
COOPERATION

The year 1974 was a period of significant develop-
ment and change in the USGS’s international pro-
gram. Three long-continued projects (Brazil, Co-
lombia, and Indonesia) were substantially completed;
extension-s into 1975 were made only on a limited
‘ basis to permit completion of reports and previously
scheduled activities. In Brazil, USGS scientists were
given short-term assignments during the first part
of 1975 for demonstration and training in hydrologic
and geologic subjects, and Brazilian participants con-
tinued to visit the United States for supplementary
instruction, 'as requested by the Government of
Brazil. In past years, the program included: (1) Ex-
ploration and appraisal of a wide variety of minerals,
including uranium and the well-known iron deposits
of the Quadrilatero Ferrifero; (2) hydrologic in-
vestigations; (3) education projects in Earth sci-
ences and techniques; (4) remote sensing; (5) geo-

258

 

chemistry; (6) geophysics; and (7) advisory serv-
ices designed to strengthen the Brazilian Earth-
science institutions. In Colombia, assistance to the
National Institute for Geology and Minerals was ter-
minated during the first part of 1975. The Colombian
program, which ran from 1963 to 1975, consisted
largely of assistance in mineral exploration and geo-
logic mapping, training in Earth sciences, and insti-
tutional development. The 5-yr Indonesian project
was terminated by P. W. Richards and R. W. Schaff
in early 1975. The project accomplished its stated ob-
jective of assisting the Geological Survey of Indo-
nesia in improving its systematic geologic mapping
capabilities and its capacity to identify, map, and
evaluate mineral and other geologic resources.

During 1974, new cooperative programs were initi-
ated in Bolivia and Yemen. The USGS and the Bolivi-
an Ministry of Mines and Metallurgy signed a
Memorandum of Understanding covering a 5-yr peri-
od; under the terms of this agreement, the USGS
will provide reimbursable technical assistance to ap-
propriate Bolivian agencies to help strengthen, en-
large, and intensify their mineral exploration and
development activities. The first projects under this
Memorandum of Understanding involve assistance
in initiating a mineral exploration fund and estab-
lishing a computerized data bank for mines and
mineral deposits.

Under an agreement with Yemen sponsored by
AID, the USGS began a 3-yr investigation of ground-
water and mineral possibilities in the northern part

~ of the country using conventional geologic techniques

and LAN DSAT—l satellite data. Objectives are to
provide information useful for the development of
water and mineral resources and to lay the ground-
work for further study by the Yemeni Government,
as well as to train Yemeni scientists and technicians
so that they can continue this work in the future.

In response to a request by the Algerian Ministry
of Hydraulics, the USGS entered into discussions
concerning a program to provide technical assistance
to the Ministry in training Algerian personnel in the
techniques of remote sensing and to develop a facility
for processing remote-sensing data.

INTERNATIONAL COOPERATION IN THE EARTH SCIENCES

The long-range Saudi Arabian project, scheduled
to end in 1975, was extended to 1978, and the USGS
program in Thailand continued under the direction
of J. 0. Morgan. The USGS was also involved in a
cooperative program with Mexico, discussed below.

Personnel of the USGS participated in a number
of Earth-science activities of the Central Treaty Or-
ganization (CENTO) during 1974. T. P. Thayer and
N. J Page took part in field studies of ophiolites and
the mineral deposits associated with them in Turkey
and Pakistan. R. P. Sharp served as the US. partici-
pant at a meeting of the Working Group on Recent
Tectonics held in Quetta, Pakistan. J. B. Cathcart,
D. F. Davidson, R. A. Gulbrandsen, and J. W. Mytton
led field excursions in the northwestern and south—
western phosphate fields of the United States; 10
scientists from CENTO regional countries and the
United Kingdom also participated. Also, E. H. Bailey
again participated in the summer field-training
course in applied mining geology for students from
the CENTO countries. These courses have been given
since 1966, and, thus far, 119 geologists and mining
engineers have received training.

The second and third International Training
Courses on Remote Sensing were held from May 30
to June 28 and September 19 to October 12, 1974,
respectively, at the EROS Data Center in Sioux
Falls, S. Dak. The courses were part of a cooperative
program developed by AID and the USGS to provide
training .for scientists and engineers of developing
countries. The purpose of the courses was to train
participants in (1) the practical applications of
LANDSAT satellite imagery and (2) the types of
aerial remote-sensing data that might be readily
available to them.

At the earlier course in the spring, 34 scientists
from 21 nations attended, and, in the fall, 20 sci-
entists were present from‘ll nations.

S. J. Gawarecki, J. 0. Morgan, and C. J. Robinove
participated as consultants in remote sensing at the
Seminar on the Application of Remote-Sensing Tech-
nology to Natural Resources Development held in
Bangkok, Thailand. The 1.-week seminar was spon-
sored by the Economic and Social Commission for
Asia and the Pacific, a United Nations organization.
Eighty-three participants from 20 countries and 5
specialized agencies and intergovernmental bodies
attended.

Following the seminar, Gawarecki and Morgan
participated as instructors in the 3-week Mekong
Coordinating Committee Training Course and Work-
shop on Application of ERTS Data to the Develop-
ment of the Mekong River Basin. The course was

 

259

attended by eight trainees, two each from Thailand,
the Khmer Republic, Laos, and Vietnam. After the
seminar, Robinove went to Australia, where he pre—
sented five 2—d courses and one 1-d course in remote
sensing, with emphasis on LANDSAT data, in Sid-
ney, Melbourne, Adelaide, Perth, and Brisbane. The
lecture circuit was sponsored by the Australian
Government.

The USGS and various other US. Federal agen-
cies are participating in joint technical cooperation
agreements that have been or are being Executed
between the United States and several Middle East-
ern countries. In Saudi Arabia, the USGS is present-
ly helping to plan specific water-resource develop-
ment projects and a national water-resource assess-
ment. Discussions have been held concerning coopera-
tion with Iran and Egypt. ~

Under a Memorandum of Understanding between
the United States and the United Nations, the USGS
provides consultation and advisory services in sup-
port of the Coordinating Committee for Joint Pros-
pecting of Mineral Resources in Asian Offshore Areas
(CCOP), a nine—nation committee supported by the
UN. Development Program. These services include
the assignment of a marine geology consultant,
Frank Wang of the CCOP secretariat stafi in Bang-
kok, to assist in planning, conducting, and coordinat-
ing regional projects sponsored by CCOP. These in-
clude a major program of research on the tectonic
development of the continental margin of Southeast
Asia in which the CCOP countries are participating
in cooperation with the Intragovernmental Oceano-
graphic Commission and the US. NSF. The USGS
also provides consultation to CCOP in analyzing
satellite imagery to support this research.

USGS participation in cooperative scientific ,in-
vestigations with other countries under the Depart-
ment of Interior’s Special Foreign Currency Program
(SFCP) continued during the year. Ongoing projects
in Yugoslavia include investigations of techniques
for mapping permeability in karst areas, seismic in-
vestigations of deep crustal structure, problems of
earthquake reconstruction, and investigations of rare
metals associated with alkalic plutons. In Poland,
projects in 1974 included studies in mining hydrolo-
gy and investigations of base-metal deposits in car-
bonate rocks. Two new SFCP projects were proposed
for Poland: studies of the geochemistry of coal and
of the comparative geology of coal basins. Three have
been proposed for India: applications of remote sens-
ing and geophysical techniques to the search for
ground water and to the search for ore deposits and
studies of the seismicity of the Himilayan front.

260

In support of the US. Antarctic Research Pro-
gram (USARP) sponsored by the NSF, the USGS is
publishing various map series and cartographic
products. Four maps in the 1:250,000—scale series,
Mount Berlin, Grant Island, Cape Burks, and Hull
Glacier of the Hobbs Coast-Marie Byrd Land area,
were compiled and are scheduled for printing. A re-
vised index, Topographic Maps, Antarctica, which
shows all maps published in Antarctica by the USGS,
is also scheduled for printing. Seventeen maps in the
1:250,000-sca1e series are in various phases of com-
pilation. Work on these maps, which cover an area
along the Marie Byrd Land Coast between the Jones
Mountains and the Hobbs Coast, will continue during
fiscal year 1976.

Under joint NSF-NASA funding, cartographic ex-
periments with LANDSAT—1 imagery included re-
vision of the 1:1,000,000—scale Ross Ice Shelf plan-
ning map along the shelf’s front and updating of the
1:1,000,000-sca1e McMurdo Sound region map. Both
maps are in final stages of compilation. The McMurdo
Sound region map will be the first map of Antarctica
that conforms to International Map of the World
specifications.

A single LANDSAT scene of the Ross Island,
McMurdo Sound, and southern Victoria Land-Dry
Valley areas was enlarged to scales of 1:250,000
and 1:500,000. Control was identifiedbn the com-
pilation image, and a fitted grid was printed on the
final products, which await publication. This experi-
mental product was developed to determine what
uses and demands could be made of similar single-
scene products within the polar scientific and logis-
tic community. In further support of investigations

GEOLOGICAL SURVEY RESEARCH 1975

maps and (or) mosaics of 14 coastal areas are be-
ing prepared at a 1:1,000,000 scale. A companion
sketch map will also be available for those areas
where LANDSAT images indicate significant
coastal changes. The 14 LANDSAT image mosaics
will be paneled into a LANDSAT image mosaic of
the continent. The resulting product, at a 125,000-
000 or 1:10,000,000 scale, will provide the first sin-
gle photoimage mosaic of Antarctica.

Copies of all maps and cartographic products are
made available to polar scientists associated with
the USARP and to scientists of the 11 member na-
tions represented on the Scientific Committee on
Antarctic Research (SCAR). To date, 77 1:250,000-
scale topographic maps covering about 820,000 km2
have been published by USGS and distributed to
SCAR.

As part of the USGS technical assistance and co-
operation programs abroad, 150 Earth scientists
and engineers from 38 countries pursued academic
or intern experience in the United States during
fiscal year 1975. Types of assistance to, or exchange
of scientific experience with, each country during
the fiscal year, are summarized in table 3. Under
USGS guidance, 1,542 participants from 95 coun-
tries had completed research, observation, aca-
demic, or intertraining programs in the United
States as of June 197 5.

Since the beginning of the technical assistance
work in 1940, more than 2,214 technical and admin-
istrative documents authored by USGS personnel
have been issued. During calendar year 1974, 98
administrative and (or) technical documents were
prepared, and 94 reports or maps were published

 

on cartographic experiments, LANDSAT image or released in open files. (See table 4.)

TABLE 3.——Techm'cal assistance to other countries provided by the USGS during fiscal year 1975

 

USGS personnel assigned to other countries Scientists from other countries trained in United States

 

 

 

 

Geochemical exploration: granites.

Country Number Type naggigfl Number Field of training
Latin America
Argentina ________ 2 Geologist _________________ D ________ _ _
3 Hydrologist _______________ D ________ _ _
1 Structural engineer ________ __
Bolivia ___________ 2 Geologist _________________ __
1 Hydrologist _____ ._ _________ __
1 Structural engineer ________ -_
Brazil ____________ ' 1 Chemist __________________ 12 Minerals exploration.
1 Geochemist _______________________ 1 Economic, structural, and regional geology.
15 Geologist _________________ A C, D ___ 1 Hydrology, water-quality studies.
1 Geophysicist ______________________ 2 Remote sensing. ' _
6 Hydrologist _______________ A, D ____ 2 Geologic evaluation of mineral deposxts.
2 Computers: mineral resources.
1 Airborne magnetometer techniques.
6 Hydrology. ‘
1 Sedimentology.
1
1

Evaporite deposits: exploration methods
and interpretation.

INTERNATIONAL COOPERATION IN THE EARTH SCIENCES

261

TABLE 3.——Techm'cal assistance to other countries provided by the USGS during fiscal year 1975—Continued

 

USGS personnel assigned to other countries

Scientists from other countries trained in United States

 

 

 

 

 

 

 

Country Number Type a’ldis’igitgfl Number Field of training
Latin America—Continued
Brazil—Continued 1 Analytical chemistry and atomicabsorp-
tion techniques.
1 Geochemistry.
1 Geochemistry; mineralogy and petrology.
3 Minerals drilling.
1 Analytical techniques.
Chile _____________ 1 Geologist _________________ A ________ _ _
1 Hydrologist _______________ D ________ __
1 Structural engineer _________ D ________ __
Colombia _________ 1 Chemist __________________ A ________ 2 Seismic research observatories.
11 Geologist _________________ A, D ______ __
1 Samples expert ___________ A ________ __
1 Structural engineer ________ D ________ __
Costa Rica ________ 2 Geologist _________________ D ________ __
1 Geophysicist ______________ D ________ _ _
Ecuador .......... 1 Structural engineer ________ D ________ 1 Remote sensing.
1 Hydrology.
Guatemala ________ 1 Geologist _________________ D ________ _ _
Honduras _________ 1 Geologist _________________ D ________ __
Mexico ___________ 1 Geologist _________________ D ________ _ -
2 Hydrologist _______________ D ________ _ _
Nicaragua ________ 1 Geologist _________________ D ________ 2 Earthquake hazard reduction.
2 Geophysicist ______________ A ________ 1 Remote sensing.
Panama __________ 1 Hydrologist _______________ D ________ _ _
Paraguay _________ 1 Hydrologist _______________ D ________ __
Peru _____________ 5 Geologist _________________ C. D ______ -_
5 Geophysicist ______________ C, D ______ __
1 Research civil engineer ____ D ________ __
1 Structural engineer ________ D ________ __
Trinidad-Tobago ___ 1 Structural engineer ________ D ________ 1 Hydrology.
Venezuela ________ 1 Geologist _________________ D ________ __
1 Structural engineer ________ D ________ __
Africa
Algeria ___________ 1 Civil engineer _____________ D ________ __
2 Geologist _________________ D ________ __
1 Hydrologist _______________ D ________ __
1 Administrative officer ___________________ __
Egypt ____________ 2 Geologist _________________ D ________ __
Ghana _____________________________________________________________ 1 Remote sensing.
Ivory Coast _______ 2 Geologist _________________ A ________ __
Kenya ____________ 2 Hydrologist _______________ B, C ______ 6 Do.
1 Hydrology.
Lesotho ____________________________________________________________ 1 Remote sensing.
Nigeria ____________________________________________________________ 1 Do.
Somalia __________ 1 Research forester __________ D ________ __
Near East-South Asia
Afghanistan _______________________________________________________ 1 Remote sensing.
2 Hydrology.
Bangladesh ________________________________________________________ 1 Remote sensing.
India ______________________________________________________________ 1 o.
5 Hydrology.
1 Exploration geology.
1 Ground-water development.
1 Hydrogeology.
2 Borehole geophysics in hydrogeologfic
investigations.
2 Water-quality studies.
1 Atomic minerals exploration.
Iran _____________ 4 Geologist _________________ C, D _____ 4 Seismic research observatories.
‘ 4 Remote sensing.
Israel _____________________________________________________________ 1 Operation of magnetic observation.
Jordan ___________ 1 Geologist _________________ C, D _____ __
Nepal ____________ 2 Hydrologist _______________ A, B, C __- 3 Ground-water investigation and hydrology.
1 Remote sensing.
1 Hydrology.
1 Ground-waterinvestigation—water
chemistry.
Oman ____________ 1 Geologist _________________ D ________

262

GEOLOGICAL SURVEY RESEARCH 1975

TABLE 3,—Technical assistance to other countries provided by the USGS during fiscal year 1975—Continued

 

USGS personnel assigned to other countries

Scientists from other countries trained in United States

 

 

 

 

 

 

 

 

Country Number Type “{{gfitgfl Number Field of training
Near East-South Asia—Continued
Pakistan __________ 1 Agricultural specialist _____ D ________ 1 Atomic absorption spectrometry.
3 Geologist _________________ D ________ 2 Remote sensing.
1 Hydrologist _______________ D ________ _ _
1 Physical scientist _________ D ________ _-
1_ Topographic engineer ______ D ________ __
Saudi Arabia _____ 4 Administrative officer ___________________ 1 Computer applications.
1 Cartographer _____________ A, B _____ 2 Computer electronics.
1 Cartographic technician ___- A, __
2 Chemist __________________ B __
2 Computer specialist ________ B __
3 Editor ____________________ A, _
6 Electronic specialist _______ A, B, C ___ __
2 General service oflicer ___________________ _-
20 Geologist _________________ A, B, C, D- __
2 Geophysicist ______________ A, B, --- _-
3 Hydrologist _______________ D ________ _-
1 Photographer _____________ A ________ __
1 Topographic engineer ______ A ________ __ .
Turkey ___________ 1 Geologist _________________ D ________ 7 Remote sensing.
1 Cartography.
1 Cartography—shaded relief.
1 Analytical methods for geochemical
exploration.
1 Seismology.
1 Sedimentology of carbonates.
Yemen ___________ 2 Hydrologist _______________ A, B, C ___ __
2 Geologist _________________ D ________ -_
Far East
Burma ____________________________________________________________ 1 Field geology and geological mapping.
1 Geochemistry.
China _____________________________________________________________ 2 Remote sensing.
2 Seismology.
Indonesia _________ 1 Cartographer ______________ A, B, C __ 5 Remote sensing.
8 Geologist _________________ A, B, C, D- 1 Publication of geologic maps.
1 Publications specialist _____ D ________ 1 Geological mapping.
Japan ____________ 2 Geologist _________________ A, B, C ___ 1 Sediment discharge and slope failure.
1 Remote sensing.
Khmer Republic ___ 1 Geologist _________________ A, B, C ___ __
Korea ____________ 3 Geologist _________________ A, B, C, D- 2 Remote sensing and interpretation.
Malaysia _________ 1 Geologist _________________ A, B, C ___ __
New Zealand _______________________________________________________ 1 Seismic research observatories.
Philippines _______ 3 Geologist _________________ A, B, C __ 1 Remote sensing.
3 Hydrology.
Singapore ________ 2 Geologist _________________ A, B, C __ __
South Vietnam ___- 2 Geologist _________________ A, B, C __ 1 Remote sensing.
Taiwan ___________ 1 Geologist _________________ A, B, C __ __
Thailand ___________ 7 Geologist _________________ A, B, C __ 3 Do.
Western Samoa __- 1 Geologist _________________ A ________ __
Other
Australia _________ 1 Geologist _________________ A ________ 1 Remote sensing.
2 Seismology.
1 Research on geology of ore deposits;
geochemical exploration.
Austria ___________ 1 Economist ________________ D _________ __
3 Hydrologist _______________ D ________ _-
1 Physicist _________________ D ________ __
France ___________ 1 Geologist _________________ D _________ 1 Paleointensity determinations.
2 Geophysicist ______________ A, D ______ 1 Photogeology—astrogeology.
3 Hydrologist _______________ A, D ______ __
Germany _________ 1 Hydrologist _______________ A ________ 1 Remote sensing.
Iceland _____________________________________________________________ 1 Radioactive logging.
Italy _____________ 2 Hydrologist _______________ A ________ 2 Remote sensing.
Netherlands ________________________________________________________ 1 Geochemistry.
Norway ___________________________________________________________ 1 Remote sensing.
Poland ___________ 1 Hydrologist _______________ A ________ - _
Romania __________________________________________________________ 1 Mathematical modeling in hydrology.
Spain ______~ ______________________________________________________ 1 Remote sensing. ,
1 Water management.
1 Hydrology.

INTERNATIONAL COOPERATION IN THE EARTH SCIENCES 263

TABLE 3.—Techm'cal assistance to other countries provided by the USGS during fiscal year 1975—Continued

 

USGS personnel assigned to other countries Scientists from other countries trained in United States

Type of

 

 

Country Number Type activity 1 Number Field of training
Other—C ontinued
Sweden ___________ 1 Hydrologist ________________ A ________ _ _
Switzerland _______ 1 Hydrologist _______________________ _ _
United Kingdom ___ 2 Geologist.-____________;_-- A B, C __- __
1 Geophysicist ______________________ _ _
1 Mining engineer __________ D ________ _ _
1 Physicist _________________ A ________ _ _
USSR ____________ 1 Hydrologist _______________ D ________ _
Yugoslavia _______ 2 Geophysicist ______________ D ________ 1 Remote sensing.

 

‘A, broad program of assistance in developing or strengthening Earth-

science institutions and cadres; B, broad program of geologic mapping and

appraisal of rresources; C, special studies of geologic or hydrologic phenomena or resources; D, short-range advisory help on geologic or hydrologic prob

lems and resources.

TABLE 4.——Techm'cal and administrative documents issued in
calendar year 1974 as a result of USGS technical and scien-
tific cooperative programs

 

Reports or maps prepared
Ap-

 

proved
Proj- for Pub-
ect publica- lished Pub-
Country or admin- tion by in lished
region istra- USGS tech- by
tive or nioal USGS
report: counter- journals
part
agencies
Afghanistan _______ _ _ 1 1 1
Africa _____________ 2 5 _ _ 4
Algeria ____________ 1 _ _ _. _ _ _
Bangladesh ________ _ _ 1 _ _ 1
Brazil _____________ 1 13 _ _ 10
Central America _ _ _ _ _ _ 1 _ _ _ _
Chile ______________ _ _ _ _ _ _ 3
Colombia __________ 2 2 1 1
Costa Rica _________ 2 1 _ _ - _
Ethiopia ___________ _ _ 1 _ _ 1
Indonesia __________ 6 3 1 2
Jordan ____________ __ 2 _- 2
Liberia ____________ 1 11 3 32
Libya _____________ _ _ 1 _ _ _ _
Nicaragua _________ __ 2 __ __
Nigeria ____________ _ _ _ _ _ _ 1
Pakistan __________ _ - 1 _ _ 3
Peru ______________ _ _ _ _ _ _ 1
Saudi Arabia ______ 6 1 7 16 5
Spain _____________ 1 - _ _ _ - _
Thailand ___________ 5 2 1 _ _
Turkey ____________ _ _ 1 _ _ 2
General ___________ 5 1 _ _ 2
Total ________ 32 66 23 71

 

INTERNATIONAL COMMISSIONS AND
PROGRAMS

On behalf of the American Association of Petro-
leum Geologists, the CCOP, and the Pacific Science
Association, the USGS is coordinating a multina-
tional effort to compile geologic, tectonic, and re-
source maps of the Pacific region. This effort is
called the Circum-Pacific Map Project. All countries
in the Pacific region are collaborating, and par-
ticipation has been organized in five panels—one
panel for each of the four quadrants of the Pacific re-

 

gion and one for the Pacific-Antarctic region. J. A.
Reinemund is serving as general chairman of the
project. The project plans to compile geologic, tec-
tonic, mineral, energy, and base maps of each of
the four Pacific quadrants and of thePacific-Ant-
arctic region at a 1: 10 million scale and tectonic and
base maps of the entire Pacific area at a 1 :20 million
scale. The base maps are expected to be ready for
publication this year, and the other maps in the suc-
ceeding 3 yr. The project is also attempting to de-
velop computerized data banks.of the information
used in compiling the maps; this bank can be used in
future revisions and updating of the maps and will
be accessible to all participating countries.

A number of USGS scientists have been involved
in the International Geological Correlation Program
(IGCP), which is a joint activity of the IUGS and
UNESCO. Reinemund is a member of the Board of
the IGCP, and P. W. Guild is a member of one of the
IGCP scientific committees. USGS scientists are co-
ordinators for two approved IGCP Projects: P..C.
Bateman for the project on circum-Pac-ific plutonism
and A. L. Clark for the project on standards for
computer applications in resource studies. In addi-
tion, E. H. Bailey, M. C. Blake, and R. G. Coleman
participate in the project on ophiolites, R. B. Neu-
man in the project on the Caledonian orogen, and
G. M. Richmond in the project on Quaternary
glaciation.

In line with the USGS’s primary responsibilities
for the U.S. Federal geothermal exploration pro-
gram, R. O. Fournier headed the U.S. Organizing
Committee for the Second U.N. Symposium on De-
velopment and Use of Geothermal Resources held in
San Francisco in May 1975. The symposium, spon-
sored jointly by the United Nations, the Department
of the Interior, the State of California, and other
public and private agencies, was the first such gath-
ering to be held in the United States and was part

264

of an effort to foster international cooperation in
developing new and alternative sources of energy.
Approximately 1,000 attending geoscientists, includ-
ing about 90 from the USGS, represented about 50
countries. Of the 130 papers delivered by representa-
tives from 17 nations, about half were concerned
with finding and evaluating sources of geothermal
energy, and half dealt with uses of this resource and
economic and legal problems. An abstract volume of
358 selected abstracts was published and available
at the meeting.

The International Energy Agency, which was
formed as a result of Secretary of State Henry
Kissinger’s Energy Conference of 1973, held its first
meeting in 1974; C. D. Masters was the USGS repre-
sentative. This organization, based in London, acts as
a clearing house for data on coal resources and re-
serves gathered from 16 member nations. The data
are sent to the USGS for inclusion in the World
Resource Data System. Knowing the coal resources
and reserves available will help the United States
and other member countries to make realistic plans
for coal utilization and to make current economic
assessments of new sources of energy and of the im-
pact of new technology on coal production.
G. H. Wood, Jr., is the U.S. representative for the
Interior Department and the USGS.

D. M. Kinney, vice president for North America
for the Commission of the Geologic Map of the
World, and P. W. Guild, president of the Subcom—
mission for the Metallogenic Map of the World, at-
tended the Commission’s plenary session held in
Paris in April 1974. Kinney reported on the progress
of small-scale geologic mapping in North America in
1972—74. D. F. Davidson, delegate, and A. L. Clark,
observer, represented the USGS at the COGEO-
DATA (Committee on Storage, Automatic Process-
ing, and Retrieval of Geologic Data) Biennial Meet-
ing held in conjunction with the Map Commission
meeting. COGEODATA is concerned with applying
computer-based techniques to advance the science of
geology.

Among the many other international commissions,
conferences, and programs in which USGS scientists
participated were the First Circum-Pacific Confer-
ence on Energy and Mineral Resources held in Hono-
lulu, Hawaii, at which seven USGS members pre-
sented papers; the International Ophiolite Confer-
ence in Medellin, Colombia, attended by J. E. Case,
R. G. Coleman, and M. R. Brock; and the Second
Pan-Arab Mineral Conference in Jiddah, Saudi
Arabia, attended by T. H. Kiilsgaard, J. A. Reine-
mund, and E. W. Tooker. Reinemund also was a

 

GEOLOGICAL SURVEY RESEARCH 1975

member of the delegation to the UN. Natural Re-
sources Committee meeting in Tokyo, Japan, and
J. E. Case represented the USGS in a workshop
sponsored by the Intragovernmental Oceanographic
Commission and the NSF, which was held in Hon-
duras in June to plan a program of research for the
Caribbean region under the International Decade of
Ocean Exploration. D. F. Davidson was the U.S.
delegate to the Minerals Advisory Committee of
CENTO at the annual meeting held in Teheran,
Iran, in December 1974 and to the CCOP meeting in
Seoul, Korea, in August. On behalf of UNESCO,
R. K. McGuire served as consultant in preparing for
a survey of the seismicity of the Andean region
(Argentina, Bolivia, Colombia, Chile, Ecuador, Peru,
Trinidad, Tobago, and Venezuela). S. T. Algermissen
and D. M. Perkins initiated a project for a seismic
risk map of southern Europe under an agreement
with UNESCO as a part of the UNESCO Balkan
Seismologic Project. J. P. Albers, as U.S. delegate,
attended the UN. Law of the Sea Conference, which
was held in Caracas, Venezuela, for 10 weeks in June
through August 1974; V. E. McKelvey attended the
third session of the conference in Geneva, Switzer-
land, early in 1975.

RESPONSE TO NATURAL DISASTERS

The USGS has been designated by the Department
of State as the lead agency in coordinating the U.S.
response to natural disasters. As part of this effort,
AID provided funds for the USGS to assist in estab~
lishing a Nicaraguan Center for Earthquake Hazard
Reduction in Managua. The center will study seis-
micity and geologic hazards and determine basic
requirements for regional zoning and construction
design. During 1974, USGS personnel on part-time
assignments advised on the installation of necessary
equipment and trained three Nicaraguans. On behalf
of AID, C. J. Robinove completed a study of the
potential uses of satellite imagery for warning and
assessment of disasters throughout the world.
Floods, fire, glacial movement, and drought are the
disasters most amenable to satellite sensing. Appli-
cations to other disasters such as earthquakes and
volcanic eruptions are promising.

MINERALS ATI'ACHE PROGRAM

An expanded minerals attaché and reporting pro-
gram, proposed jointly by the USGS and the Bureau
of Mines, was approved and is being established by
the Department of State. Attachés will be stationed

INTERNATIONAL COOPERATION IN THE EARTH SCIENCES

initially in Johannesburg, South Africa; Rio de .

Janeiro, Brazil; New Delhi, India; Kinshasa, Zaire;
La Paz, Peru; and Canberra, Australia. Orientation
courses to acquaint these attaches with the opera—
tions and information needs of the USGS and the
Bureau of Mines have been developed; the first
course will be given early in 1976. Minerals attachés
will have greater responsibilities than they did in
the past, since there is a serious need for accurate
information not only on worldwide production of
minerals in short supply in the United States but
also on the availability of foreign supplies of these
minerals for meeting world requirements in the
future.

SUMMARY BY COUNTRIES

ARGENTINA

J. M. Botbol and R. W. Bowen completed a 6-week
assignment with the United Nations to evaluate the
initial design stages of a data bank project. Their
study analyzed the mineral-resource data bank, its
relation to other projects, its design, and its poten-
tial for growth.

BOLIVIA

In a recently completed study of cadmium—rich de-
posits of the Berenguela district near the common
corner of Bolivia, Chile, and Peru, C. M. Tschanz
reported that the rare cadmium sulfide, hawleyite,
and sphalerite and wurtzite containing as much as
18 percent cadmium were found in concentrically
banded schalenblende nodules from lead-zinc-cadmi-
um-copper-silver veins collected by T. H. Kiilsgaard
in the early 1960’s.

Several systems of cadmium-rich veins and cad-
mium-bearing thermal spring deposits are within an
area of about 50 kmz. The veins average 2 to 6 per-
cent Cd but locally contain as much as 13 to 15 per-
cent. The district is within a north-south belt just
east of an active volcanic chain that contains several
other widely scattered cadmium-rich basemetal
deposits.

The highest cadmium content and the lowest zinc-
cadmium ratios (1.1 to 1.5) are in concentrically
banded nodules that contain a few thin layers of
orange hawleyite and many layers of sphalerite,

wurtzite, galena, and other minerals. The hawleyite, i

earlier identified by M. E. Mrose (written commun.,
1969), was the third reported occurrence of this

mineral. The extremely high cadmium content of g

 

265

some sphalerite and wurtzite, which was identified
from X—ray powder-diffraction films of hand-picked
grains by Tschanz, was first suspected by B. F. Leon-
ard because of the expanded cell dimensions and
later proved by G. A. Desborough’s microprobe
analyses.

In one nodule containing hawleyite layers, Des-
borough found ranges of from 0.14 to 18.0 percent
Cd and 56.9 to 65.9 percent Zn in 26 zinc sulfide lay-
ers with very low contents of iron and manganese.
Ten of these layers contained 11.5 to 18.0 percent
Cd, in comparison with a maximum of about 4.7
percent in layers of sphalerite and wurtzite previ-
ously reported in the literature. Only six zinc sulfide
layers contained less than 1.8 percent Cd. Two or
three zinc sulfide layers analyzed in‘ two other
nodules had cadmium contents of 0.32 to 2.6 and 4.6
to 9.8 percent. The higher values were in a nodule
that did not contain layers of hawleyite. Greenockite,
the only cadmium mineral reported in the literature
on the district, was not found and probably was re-
ported as the result of erroneous identification of
mixtures of hawleyite, wurtzite, and sphalerite.

BRAZIL

The program of technical cooperation with Brazil
was focused in 1974 on training participants in the
United States, on technical training and consultation
by USGS personnel on short assignments in Brazil,
and on consultation visits to the United States by
senior Brazilian officials.

A total of 37 Brazilian geologists, hydrologists,
and technicians received formal training at univer-
sities in the United States and in laboratories and
field programs of the USGS. Specific advisory assist-
ance and technical training included field and lecture
courses in (1) field geology, (2) sedimentary, igne-
ous, and metamorphic petrology, (3) structural ge-
ology, (4) weathering processes, (5) field geochemis-
try, (6) photogeology and remote sensing, and (7)
magnetic surveying. A total of 24 USGS specialists
on short-term assignments in Brazil provided the
training and advisory assistance.

In October 1974, agreement was reached between
AID, the USGS, and the Brazilian Ministry of Mines
and Energy on an extension, through 1975, of the
loan program, which was to have expired in 1974.

Studies of regional aeromagnetic data from Minas
Gerais made by W. F. Hanna and A. H. Chidester as
part of a training course in Rio de Janeiro indicated
that highly distinctive anomalies are associated with
various types of igneous rocks having limited ex-

266

posures. Broad areas of short-wavelength anomalies
corresponding to diverse magnetization inclinations
correlate with extensive basaltic flows, presumably
possessing strong remanent magnetization. Narrow
northwest-trending linear anomalies that extend
continuously for over 150 km are associated with
nearly vertical diabase-dikes outlining zones of crust-
al weakness. Of great economic interest are high-
amplitude equidimensional negative anomalies, each
flanked by smaller positive anomalies to the north
and to the south, which are caused by the induced
magnetization of alkalic igneous rock intrusions and
their weathering products, rich in Nb, Ta, Sn, Tl, U,
and rare-earth elements. The aeromagnetic data pro-
vide an almost indispensable tool for regional geo-
logic mapping.

During 1974, six USGS short-term advisors as-
sisted Brazilian agencies with measuring stream
discharge by indirect methods, using satellite data
for river-basin management, analyzing hydrologic
data, collecting and evaluating water-quality data,
and applying mathematical modeling to hydrology.

C0 LOM BIA

The cooperative program between the USGS and
its Colombian counterpart, the Instituto Nacion-al de
Investigaciones Geologica-Mineras (INGEOMINAS),
neared completion in 1974. AID agreed to an exten—
sion of the loan through 1975, but activity after
April 1975 was to be limited to training and consulta-
tion‘ by USGS personnel on short-term assignments
in Colombia and to academic training of Colombian
participants in universities and USGS facilities in

. the United States.

Under the program in 1974, purchase and installa-
tion of equipment in analytical and laboratory facili-
ties brought these facilities to a high level of compe-
tence. Academic training in the United States was
provided to Colombian participants. On-the—j ob train-
ing and instruction in geologic mapping and mineral-
resource evaluation provided valuable experience to
a cadre of Colombian geologists in the Popayan dis-
trict; associated investigations disclosed potential
mineral resources. USGS consultants provided tech-
nological assistance in the development of identified
potential mineral deposits.

Under the direction of D. L. Rossman, 10 Colombi-
an geologists almost completed geologic mapping and
geochemical~ sampling of an area of nearly 15,000
km? in the vicinity of Popayan. An ancient gold
placer was rediscovered, and several areas of anoma-
lously high Cu, Au, Sb, Zn, and Hg were noted.

 

GEOLOGICAL SURVEY RESEARCH 1975

Several of these areas having potential economic
value will be investigated further.

M. R. Brock and J. H. McCarthy, Jr., sampled a
bed of limestone adjacent to a lead-silver vein in the
Ubala area. Spectrographic analysis of the samples
indicates a content of 2 percent Pb and 93 g Ag per
tonne. A program of shallow drilling in this area and
prospecting in the vicinity of numerous similar oc-
currences in the region was planned by INGEO-
MINAS to evaluate the possible Mississippi Valley-
type base-metal deposits. .

Geochemical investigations were carried out by
J. G. 'Evans and Colombian counterparts in the Buca-
ramanga area and by McCarthy in the Gachala-
Ubala areas. Analytical work on the samples is being
done by INGEOMINAS.

J. B. Cathcart reported that geologic investigap
tion and mineral-beneficiation studies of phosphate
deposits in Colombia indicate that several deposits
can be mined in the near future and that potential
phosphate resources in Colombia are large. The TVA
has undertaken a program of sampling, physical and
chemical testing, and beneficiation at Sardinata, fol-
lowing a plan devised by Cathcart.

COSTA RICA

A. M. Rogers served as an instructor in seismo-
graphic data recording and data analysis for the
Escuela Centroamerica de Geologia at San José,
Costa Rica, under the sponsorship of the Organiza-
tion of American States. He also evaluated the pres-
ent seismograph stations in Costa Rica.

W. D. Carter advised the AID mission in methods

. of obtaining data for a cadastral survey of the Rio

Chambacu area of north-central Costa Rica.

INDONESIA
USGS assistance project

The AID-sponsored Indonesian project was con-
cluded December 31, 1974, after completing its sched-
uled 5-yr program. Although its main efforts were
devoted to increasing the geologic mapping and map
publication activities of the Geological Survey of
Indonesia (GSI), support was also provided in geo-
physics, analytical work, fission-track age dating,
and geochemistry.

GSI is publishing geologic quadrangle maps of
Java in color at a 1:100,000 scale and off Java at a
1:250,000 scale. In addition, the geology of 16 maps
covering all of Indonesia at a 1:1 million scale is
being compiled from previous work and current geo-

INTERNATIONAL COOPERATION IN THE EARTH SCIENCES

logic mapping. At the end of 1974, five maps of Java,
one of Sumatra, and two of Sulawesi had been pub-
lished. Color proofs were being reviewed of 3 Java
maps, 1 Sumatra map, 1 island of Sumbawa map, and
the first of 16 maps at a 1 : 1 million scale. Cartogra-
phy or field work were in progress on another 15
maps.

Most of the maps cover areas of economic interest
and provide the geologic background for mineral
studies. Other maps. such as those of Sulawesi and
Timor, cover areas critical to the interpretation of
plate tectonics.

A two-man project continued the geological map-
ping and map publication support into the first 3 mo
of 1975.

Topographic mapping

As a result of a request from the Government of
Indonesia and AID, the Topographic Division of the
USGS agreed to send a mapping specialist to Indo-
nesia to evaluate its mapping capabilities and assist
the Government in developing a coordinated national
mapping plan. This plan would meet requirements
for natural-resource appraisal and development,
land-use studies, and identifying priorities with sur-
veying and mapping to meet short— and long-range
objectives. The report resulting from this study was
completed and transmitted to Indonesia.

Multispectral remote-sensing projects

A multidisciplinary remote-sensing project was
initiated in 1973 in Indonesia using the relatively
simple multispectral aerial camera as a remote-
sensing tool. In January 1974, a team consisting of
S. J. Gawarecki, K. H. Szekielda, and R. R. Thaman
assisted Indonesian scientists in interpreting multi-
spectral data from an aerial survey of the island of
Bali. Eleven Indonesian investigators from agencies
involved 1n agriculture (soils and pest control), fish-
eries, forestry, geology, land-use studies, and
oceanography participated.

Plate tectonics of the Indonesian region

The integration of data from onshore and offshore
geologic investigations with marine geophysical and
seismological data yielded much insight into plate-
tectonic history and processes in W. B. Hamilton’s
continuing study of Indonesia and a large surround-
ing region. Throughout Cenozoic time, this region
absorbed the complex subduction and strike-slip
faulting by which Australia and the Indian Ocean
moved northward and the Pacific Ocean moved west
northwestward relative to mainland Asia. As the

 

267

megaplates move steadily along, small plates break
off or form by spreading, deform internally, or fuse
to other plates; subducting arcs on the edges of
plates collide with other arcs or plates; subduction
ceases at one side of an arc and starts at the other.
Great wedges of mélange and imbricated sedimen-
tary and crystalline rocks are scraped off against the
overriding plates of the subduction zones. Some of
the processes under study are also those that cause
the formation of deposits of metallic minerals and of
some types of oil fields; the developing synthesis has
already assisted in focusing the search for metals
and fuels in the region.

KENYA;

N. E. McClymonds, in cooperation with the Ken-
yan Ministry of Water Development, made recon-
naissance ground-water studies in Northeastern
Province. Drilling of test holes and production wells,
intended primarily to support Kenya’s National
Range and Ranch Development Project, began at the
end of 1974.

MEXICO

The 5—yr Mexico-US. cooperative program of min-
eral exploration in the Sonoran environment, spon-
sored by the NSF, emphasizes copper exploration. As
a part of this program, M. D. Kleinkopf and counter-
part collaborated on establishing the Inter-American
Geodetic Survey datum at new gravity bases at
Nacozari and other points and made plans for the
continuation of the geophysical program.

G. H. Allcott, principal investigator for the pro-
gram, and his associates completed geochemical sam-
pling in the La Florida-Barrigon district, and a geo-
logic map at a 1 : 10,000 scale was prepared covering
40 km2 of the district in the area of the north-trend-
ing Sierra Copercuin.

In May 1974, in cooperative investigations with the
Consejo de Recursos Naturales No Renovables of
Mexico, the USGS discovered a phosphate deposit in
the Miocene _ Monterrey Formation. Fieldwork
showed that the deposit has a strike length of 50 km,
is at least 100 m wide at the outcrop, and can possibly
be mined for at least 200 m under some overburden;
the thickness of the bed ranges from about 1 to at
least 2.5 m. The P205 content ranges from 5 to about
20 percent and probably averages about 15 percent.
The rock consists of (1) carbonate fluorapatite in
rounded pellets and scattered nodules and (2) quartz
grains cemented by a mixture of clay (kaolinite),
cristobalite, and clinoptilolite. Sparse calcite is pres-

268

ent in some samples, and some pellets may be phos-
phatized foraminifers. Since drilling has not yet been
done, the‘extent of the deposit in the subsurface is
not known. From the surface data, at least 30 mil-
lion tonnes of material may be present close enough
to the surface to be mined by open-pit methods. The
potential for this deposit is very large; similar phos-
phate is present in the Miocene of southern Califor-
nia. If the phosphate beds are continuous or semi-
continuous, the deposit could be very large. Rock
minable under present conditions, however, may be
limited to the moderate tonnage that can be mined
by open-pit methods.

NEPAL

G. C. Tibbitts, Jr., and William Ogilbee, in coopera-
tion with the Nepalese Department of Irrigationand
Hydrology, completed two ground-water exploration
projects in the western Terai of Nepal.

In the 1,800—km2 Bheri Zone, 45 test holes (a total
of 8,077 m drilled) showed that largeyield wells are
not uniformly distributed. In the northeastern part
of the zone, adjacent to the Siwalik Range, naturally
flowing wells occur. Analyses of water from wells in
the area showed a low to very low sodium content
and medium to high salinity.

In the Seti and Mahakali zones, an area of 3,720
km2 west of the Bheri Zone, 45 test holes (a total of
5,882 m drilled) showed that well yields vary, but the
potential for irrigation water from wells is good. In
much of the area, artesian pressure is high, and pre—
cautions must be taken in constructing wells. Analy-
ses of water from wells indicated that sodium con-
tent is low to very low and salinity is average.

OMAN

The mineral resources of northern Oman were in-
vestigated by R. G. Coleman and E. H. Bailey under
an agreement between the USGS and the Ministry
of Development of the Sultanate of Oman during late
1973 and early 1974. The purpose of the investiga-
tion was to evaluate the mineral potential of north-
ern Oman and to recommend ways to utilize any
viable mineral deposits that were found. Economical-
ly, the most important rock unit in the Al Hajar
(Oman Mountains) is the Semail ophiolite because
nearly all the ore deposits are associated within it.
The Semail ophiolite is considered to be a slab of
ancient oceanic crust thrust onto the edge of the
Arabian plate during Late Cretaceous time. The
oceanic crust apparently formed at a spreading cen-
ter within the Tethyan Sea some time during the

 

GEOLOGICAL SURVEY RESEARCH 1975

Mesozoic. The most significant ore deposits are cop-
per-bearing massive sulfides situated near the top of
the Semail pillow lavas; commonly associated with
these sulfide bodies are iron-rich sediments (um-
bers). The surface expression of these massive sul-
fides is characterized by brightly colored gossans,
and ancient slag piles are situated near many of
them. Archeological evidence suggests that the
Oman copper deposits may have been worked as
early as 2500 RC. and could have been the source of
copper used in the ancient city of Dilmun, on the
island of Bahrain. The geologic similarity between
the copper-bearing massive sulfide deposits of Cy-
prus and Oman is striking. From this analogy and
the most recent research on the origin of the Cyprus
deposits, it seems that the Oman deposits are pro-
duced by sea-floor-spreading processes rather than
from a postemplacement hydrothermal source. Drill-
ing of the gossans by a Canadian exploration firm
(Prospection Ltd.) revealed considerable tonnage of
ore-grade copper. The USGS investigation revealed
also the presence of chromite in the ultramafic parts
of the Semail ophiolite, along with extensive Maes-
trichtian iron laterite developed on the tops of the
exposed ophiolite.

PAKISTAN

Maps prepared by digital computer classification
of LANDSAT—l MSS data were used by R. G.
Schmidt to select 30 prospecting targets in the
Chagai District of Pakistan; 5 of these proved to be
areas of hydrothermally altered porphyry containing
abundant pyrite. At least part of the mineralized
porphyry is copper bearing.

The known porphyry copper deposit at Saindak
was used as a control or training area from which
empirical maximum and minimum apparent reflec-
tance limits were selected for each of four MSS
bands in each rock type classified, and a relatively
unrefined classification table was prepared. Where
the values for all four bands fitted within the limits
designated for a particular class, a symbol for the
presumed rock type was printed by the computer at
the appropriate location, and a classification map
was formed. Drainage channels, areas of mineralized
quartz diorite, areas of pyrite-rich rock, and the ap-
proximate limit of propylitic alteration were very'
well delineated on the computer-generated map of
the control area.

The classification method was then applied to the
evaluation of 2,100 km2 in the western Chagai Hills
east of the control area. During October 1974, a par-

INTERNATIONAL COOPERATION IN THE EARTH SCIENCES

tial check of the results was made in the field in co—
operation with the Government of Pakistan’s Re-
source Development Corporation. Thirty prospecting
targets were selected by evaluating the digital classi-
fication map, and 19 were visited. Of these, 5 locali-
ties comprising a total outcrop area of 4.7 km2 are
hydrothermally altered rock, mostly silicified and
containing sericite and clay minerals and 5 to 10
percent pyrite. The pyritic rock is believed to be the
pyrite zones of porphyry copper-type deposits. One
sample of unleached rock contained 0.3 percent Cu,
but the presence of copper or other valuable metals
beyond trace amounts has not been established for
most of the altered area. Three of the five sites may
be parts of the same partly hidden mineralized area.

Surficial rock in the altered areas is intensely
leached; the former presence of sulfides is indicated
by voids, ochers, and iron-oxide stains. Residual
blocks still containing fresh sulfide are relatively
rare. Secondary copper minerals are present at a few
places but are very sparse in most of the leached
rock. Schmidt was not able to judge how much cop-
per was present before leaching, but, if even a minor
amount was there, the possibility of a secondary en-
riched zone at depth seems very good.

The results of the experiment show that outcrops
of hydrothermally altered and mineralized rock can
be identified from LANDSAT—l data under favor-
able conditions. The empirical method of digital com-
puter classification of the M88 data is relatively un-
refined and rapid. The five mineralized prospecting
sites identified are in a generally favorable region,
but no sulfide mineralization was known near these
places when the investigation began.

PERU

Excellent short- and long-period seismograms reg-
istered a large landslide in the Peruvian Andes. The
approximate location was 185 km southeast of Huan-
cayo. The landslide, which took place April 25, 1974,
created a very large natural dam on the Mantaro
River. A microearthquake field unit was deployed by
the Instituto Geofisico del Peru in order to monitor
the postlandslide activity. Some of the results of this
study are: (1) The seismic recordings showed a mul-
tiple landslide mechanism (the largest landslide had
a magnitude of 4.7) and a total seismic release ener-
gy of 6X 1019 ergs; (2) the time delay between land-
slides is between 40 and 50 s; and (3) the total time
duration was 4 min. This landslide was the first of
this order of magnitude to be recorded so clearly to
distances of 580 km on long- and short-period seismo-

 

269

graph systems. This work was a joint effort by mem-
bers of the Instituto Geofisico del Peru and a member
of the Geological Survey of Peru, with USGS
participation.

POLAND

The USGS, under a Department of Interior agree-
ment with the Government of Poland under the Spe-
cial Currency Program (Public Law 480), is responsi-
ble for monitoring Poland’s Earth-science research
projects. One project involves the influence of mining
on the water economy in an area near Katowice in
the Upper Silesian lead-zinc and coal basin. G. C. Tay-
lor, Jr., and A. V. Heyl reported that 10 to 12 t of
water must be pumped for each tonne of ore taken
from mines in karstic dolomites and limestones in a
4,500-kmg area. About 500 mein of water of ac-
ceptable chemical quality is pumped from lead-zinc
mines in Triassic carbonate rocks, and about 180 m3/
min is pumped from coal mines in carboniferous
elastic rocks. An additional 420 mein of water
from coal mines is saline and cannot be used; carbon-
14 analyses of the coal mine saline water showed that
it is more than 40,000 yr old.

SAUDI ARABIA

A work agreement for investigations in Saudi
Arabia was signed by the USGS and the Saudi
Arabian Ministry of Petroleum and Mineral Re-
sources in 1963, and work begun then has been
extended four times, each extension for a 3—yr period.
The third extension of the work agreement became
effective December 1, 1972, and ran until September
12, 1975. However, the USGS negotiated a fourth
extension of the work agreement to begin in July
1975 and continue for 3 yr in accordance with the
Hegira calendar. Emphasis in the third program was
on detailed geologic mapping as an aid to mineral
exploration and on the improvement of the Ministry’s
technical capability.

Mahd adh Dhahab

R. G. Worl and R. J. Roberts (USGS) and Abdul-
aziz Bagdady (Saudi Arabian Ministry of Petroleum
and Mineral Resources) reported that the geologic
perspective of the Mahd adh Dhahab gold-silver dis-
trict in the central part of the Arabian Shield sug-
gests a significant resource that may be minable in
the near future. This evaluation is based upon de-
tailed mapping, surface geochemical surveys, de-
tailed study and analysis of core samples from eight
diamond-drill holes, examination and synthesis of

270

all older geologic and economic data, a detailed re-
port prepared by an outside consultant, and the
examination and evaluation of the district by several
mining and exploration firms.

Two types of deposits are being evaluated: rela-
tively high grade but erratically distributed vein de-
posits and large-tonnage low-grade deposits. Both
types are situated in a north-trending zone of vein-
ing, shearing, alteration, and metallization 1,000 m
in length and at least 200 m in width. Limited dia-
mond drilling in the southern and central parts of
the zone has penetrated several metal—bearing veins.
The largest metallized intercept is 24 m of core
length (19.2 In true width) that averages 11 ppm
(g/t) Au, 60 ppm (g/t) Ag, 0.5 percent Cu, and 1.2
percent Zn. A higher grade zone within this 24 m is a
6-m core length (4.8 m true width) that averages 42
ppm (g/t) Au and 207 ppm (g/t) Ag. Further ex-
ploration is planned in this zone. The area of the low-
grade deposit, in the northern end of the zone, was
intensively mined during ancient times (1000 RC.
and 7 50—1258 AD.) and by the Saudi Arabian Min—
ing Syndicate in 1930—54. Early production is not
known but may have exceeded 31,103 kg gold-silver
bullion; production in 1939—54 totaled 23,818 kg
fine gold and 31,166 kg silver. Most of the high-
grade veins have been mined from this deposit, but
significant gold-silver values remain in intervein
areas and in veins too narrow to be stoped. The de-
posit is exposed over an area of about 100,000 m2;
further studies to evaluate the grade of material in
this block are planned.

Kutam

Regional and detailed mapping by R. E. Anderson
in the Kutam area clarified events bearing on the
genesis of mineralization. The sequence of events
follows:

1. Ancient layered sedimentary and volcanic rocks
were tilted and invaded by quartz porphyry
sills. Subsequently, all rocks were metamor-
phosed to'the amphibolite facies and were local-
ly silicified.

2. Subsequently, during retrograde metamorphism,
biotite, muscovite, and garnet were replaced by
chlorite. Plagioclase was replaced by epidote,
zoisite, and calcite.

3. Later, temperature was reelevated; during em-
placement of large granodioritic to quartz mon-
zonitic plutons, the rocks were recrystallized,
and hornblende, plagioclase, and biotite were
formed.

 

GEOLOGICAL SURVEY RESEARCH 1975

4. Subsequent copper and zinc mineralization evi-
dently followed the recrystallization period.
Gahnite in association with quartz indicates
anomalous concentrations of zinc in a contact
metasomatic environment. Examination under
the microscope indicates that the gahnite was
partially altered to mica and sphalerite during
the simultaneous deposition of zinc and copper
sulfides, the suggestion being that the environ-
ment degraded from a high-temperature meta-
somatic to a lower temperature hydrothermal.
Possibly the anomalous mass of highly foliated
rock at the Kutam prospect served as a perme-
able channelway for the passage of metal—
bearing solutions during the final phases of the
contact metasomatic recrystallization event
and a subsequent lower temperature hydro-
thermal event. Accordingly, the sulfide min-
eralization and associated silicific-ation are in-
terpreted as being the final events in a long
and complex metamorphic history.

Genesis of massive sulfide and disseminated deposits

Massive and disseminated iron, nickel-iron, and
copper-zinc sulfide deposits in Saudi Arabia are be-
ing studied in the field and laboratory. Field studies
by R. J. Roberts, R. G. Worl, F. C. W. Dodge,
W. R. Greenwood, R. E. Anderson, and T. H. Kiils—
gaard showed that the deposits formed in both vol-
canic and plutonic rocks. Some deposits in volcanic
rocks show finely laminated pyrite (Wadi Wasat,
iron; Wadi Qatan, iron and nickel). Initially, these
deposits may have accumulated syngenetically, but
they have been metamorphosed and complexly de-
formed. The source of nickel in the Wadi Qatan de-
posit is considered by Dodge to be late—stage hydro-
thermal. Assays of samples from the Wadi Wasat
deposit indicate a low nickel content; apparently,
late-stage hydrothermal processes were weak or
absent here.

copper-zinc massive sulfide deposits at Wadi Bidah
are partly in calcareous tuff and partly in intrusive
quartz porphyry. R. L. Earhart in earlier work con-
sidered these deposits to be volcanogenic, but Roberts
and Worl consider them to be epigenetic. Dissemi-
nated copper-zinc deposits at Kutam are in a sericite
and chlorite schist and in a quartz porphyry intrusive
body. According to R. E. Anderson, the sulfide min-
erals occur mainly at the intersections of two cleav-
ages and are epigenetic. Studies on lead isotopes are
being carried on by B. R. Doe and M. H. Delevaux;
these studies should further clarify the geologic his-
tory of the ore deposits.

INTERNATIONAL COOPERATION IN THE EARTH SCIENCES

Cratonization in the Arabian Shield

The Arabian Shield in southWestern Saudi Arabia
was cratonized during the late Proterozoic, accord-
ing to W. R. Greenwood, D. G. Hadley, R. E. Ander-

son, R. J. Fleck, and D. L. Schmidt. Early cratonal 1

development began with the deposition of calcic to

calc-alkalic and basaltic to dacitic volcanic rocks and '

immature sedimentary rocks that subsequently were
moderately deformed, metamorphosed, and intruded
about 960 my. ago by dioritic batholiths of mantle
derivation (ST Sr/S6 Sr=0.7028) .

A thick sequence of calc-alkalic andesitic to rhyo-
dacitic volcanic rocks and volcanoclastic wackes was
deposited unconformably on this neocraton. Regional
greenschist-fades metamorphism, intensive defor-
mation along north-trending structures, and intru-
sion of mantle-derived (”Sr/“Sr=0.7028) dioritic to
granodioritic batholiths occurred at about 800 my
At about 785 m.y., granodioritic to quartz monzonitic
gneisses (“Sr/“Sr=0.7028 and 0.7035) were em-
placed in part as gneiss domes surrounded by am-
phibolite- to granulitE-facies metamorphic rocks. Ex-
tensive deposition of similar volcanic and clastic
rocks elsewhere in the region seems to have been in
part synchronous with orogeny at 785 my and to
have followed it. These deposits and the older rocks
were deformed along north-trending structures,
metamorphosed to greenschist facies, and intruded
by calc-alkalic plutons (“Sr/so Sr=0.7035) between
600 and 650 m.y. B.P. g

Late cratonal development involved extensive
graywacke sedimentation associated with small
amounts of andesitic and rhyolitic volcanism, struc-
tural deformation, metamorphism to greenschist
facies, and intrusion of quartz monzonite and granite
between 570 and 550 my Cratonization appears to
have evolved in an intraoceanic island-arc environ-
ment of comagmatic volcanism and intrusion.

New gravity data in southern‘ Red Sea

A complete Bouguer gravity anomaly map of the
Farasan Islands and the adjacent coastal plain was
compiled on the basis of 145 observations. The prin-
cipal features of the map are a troughlike gravity
minimum over the Farasans, a row of gravity highs
along the eastern part of the coastal plain, and an
extremely steep gravity gradient (4 to 5 mGal/km)
in the eastern part of the mapped area. The trough-
like gravity low over the shelf is interpreted to be
caused by anomalous thicknesses of evaporites, and
the gravity highs are believed to be associated with
observed high-amplitude magnetic anomalies and, in
some cases, with exposures of mafic igneous intrusive

271

; rocks. Two classes of models were devised, one as-

 

suming a downfaulted continental crust‘beneath the
coastal plain and shelf sediments and the other an
oceanic crust under the coastal plain and shelf. Com-
puted gravity profiles for the two models show that
only the oceanic crust model, which has sediments
thinning toward the Arabian Shield, produces a pro—
file that fits bo-th the shape and the magnitude of the
observed gravity gradient. This suggests that the
gradient, located along the eastern edge of the coast-
al plain, demarcates the boundary of the continental
margin.

THAILAND

D. R. Shawe and R. J. Hite, working in cooperation
with counterparts in the Royal Thai Department of
Mineral Resources, completed a field appraisal of the
geology of parts of Thailand and a study of the rela-
tion of known mineral deposits to the geology. It is
anticipated that the work will result in a better esti-
mate of the mineral-resource potential than now
exists.

Hite continued to cooperate with the Department
of Mineral Resources and with scientists of the Gov-
ernment of Laos in evaluating the potential for
potash deposits in rocks of the Khorat Plateau.

LANDSAT program

The building of a viable Thai LANDSAT program
continued under the leadership of J. 0. Morgan,
USGS project coordinator, and the sponsorship of the
United States Operations Mission in Bangkok. All
major Thai agencies involved with agriculture, fores-
try, geology, and land use are now using LANDSAT
data for mapping purposes. A photographic labora-
tory to print and process LANDSAT images for dis-
tribution within Thailand is being furnished and is
in operation.

YEMEN ARAB REPUBLIC
Topographic mapping

Eleven 1 :20,000-scale metric contour orthophoto-
base maps of Wadi Mawr were delivered in Novem-
ber 1974 to the Director General of the Tihama
Development Authority. Additional work is needed
to make the geographic names conform to the trans-
literation system developed for Arabic by the US.
Board on Geographic Names. The maps are being
used for preliminary planning by irrigation engineers
and other specialists making agricultural, population,
social, and environmental studies in the area.

272

Ground-water studies

J. J. Jones reported that a 3—yr project begun in
cooperation with the Ministry of Agriculture and the
Minerals and Petroleum Authority of the Yemen
Arab Republic has three segments: (1) A ground-
water survey north of lat 15° N., (2) compilation
and interpretation of LANDSAT images of the en-
tire country, and (3) a minerals survey north of lat
15° N. The first two activities have begun.

Reconnaissance of water resources was made in
selected areas, and five test holes totaling 512 m
were drilled. Water levels in the $an‘a’ basin de—
clined about 2 m during the year, and those in the
‘Amran valley declined at varying but lesser rates.

LANDSAT images were compiled for part of the
country, and field checking of ground truth was un-
derway at the year’s end.

ANTARCTICA

Geologic field studies were not undertaken by
USGS personnel during the 1974--75 austral summer
in Antarctica. However, work continued on map com-
pilation and on laboratory studies of the petrology,
geochemistry, geochronology, and paleontology of
samples collected during previous expeditions to the
southern part of the Antarctic Peninsula, the Pensa-
cola Mountains, and the central part of the Trans-

 

 

  

\

 

1000 KM

 

INDEX MAP

 

GEOLOGICAL SURVEY RESEARCH 1975

antarctic Mountains. (See index map.) These contin-
uing studies, which are part of USARP, are in coop-
eration with the Office of Polar Programs of the
NSF. Progress in Antarctic aerial photography and
topographic mapping, which are functions of the
USGS, is reported in the next chapter.

Chloritic replacement of anthracite plant remains

, Woody plant fragments from the southern part of
the Antarctic Peninsula are strongly metamorphosed
and usually composed of coal similar to that in as-
sociated thin beds of anthracitic coal. Plant pieces
generally are strongly cleated, having joints charac-
teristically resembling a dense boxwork and contain-
ing angular pieces of coal in interstitial spaces. In
some examples, however, interstitial material is not
coal but consists of a nonswelling chloritic mineral,
probably of metamorphic origin, that so closely dup-
licates the coaly joint pattern that physical replace-
ment is indicated. Even at elevated temperatures in
a coke oven, anthracite remains insoluble and inert.
However, the Antarctic occurrences suggested to
J. M. Schopf that, under high confining pressures in
a natural environment, anthracite may dissolve so
that bulk interchange with chloritic constituents can
take place.

Environmental studies in the Pensacola Mountains

The PensaCola Mountains lie in a remote and sel-
dom-visited part of Antarctica. The area is relatively
uncontaminated by the effects of human activity or
animal visitations in comparison with areas near
Antarctic stations or other more traveled regions.
Prior to 1974, except for a brief visit by a 1957 IGY
party, the Pensacola Mountains had been visited
only by reconnaissance geologic, geophysical, and
geodetic survey parties of the USGS. In the expecta-
tion that activity in this area will increase in future
years, A. B. Ford (USGS), during a brief visit to
the northern Pensacola Mountains in January 1974,
collected aseptic samples of soils for baseline studies
by which to monitor possible effects of future con-
tamination. Three sampled sites are on Rosser Ridge
in the Cordiner Peaks, and three are on Mount Lech-
ner in the Forrestal Range. The soils were analyzed
for abiotic properties and microorganism contents
by R. E. Cameron (Darwin Research Institute).
The Rosser Ridge soils are comparatively more
weathered than the Mount Lechner soils and have
moisture and mineral contents more favorable for
microorganism activity. Coliforms and fungi are
absent in the soils from both areas, and bacterial

INTERNATIONAL COOPERATION IN THE EARTH SCIENCES

contents are generally low in comparison with those
from other' Antarctic areas (Cameron and Ford,
1974).

Age and distribution of radiogenic argon in Antarctic basalt
flows and dolerite sills

Jurassic basalt flows and dolerite sills of the Fer-
rar Dolerite in the central Transantarctic Mountains
yield ages ranging from 110 to 180 m.y. by conven-
tional K—Ar analysis. Because these rocks are vir-
tually undeformed and, being the youngest strati-
graphic units in the region, were never deeply buried,
postcooling thermal disturbance of the ages cannot
be invoked as a cause for young ages. Both a reliable
time of extrusion of the basalts and a confirmation of
an argon-loss interpretation are provided by ”Ar/
39Ar incremental heating experiments. Flows with

 

273

the oldest conventional K-Ar ages yield “Ar/”Ar age
spectra with plateaus typical of undisturbed samples.
These ages group closely between 170 and 175 m.y.
The fact that conventional ages less than 170 m.y.
are also poorly reproducible suggests inhomogeneous
distribution of radiogenic argon. The “Ar/”Ar age
spectra from these samples are similarly variable but
clearly indicative of argon loss, since ages of gas
fractions vary from 180 to 120 m.y. Because age
disturbance is greatest in samples with considerable
amounts of devitrified glass and is not observed in
the few originally holocrystalline rocks, R. J. Fleck
(USGS) and J. F. Sutter and D. H. Elliot (Ohio State
Univ.) concluded that progressive devitrification of
the basalts is responsible for the inhomogeneous dis—
tribution of argon, some of which was lost from the
rock systems.

TOPOGRAPHIC SURVEYS AND MAPPING

NATIONAL MAPPING PROGRAM

New requirements for basic data to inventory,
develop, and manage the country’s natural resources
are reshaping the national mapping program. A
major function of the USGS has been to prepare and
maintain maps in the national topographic series,
which covers the United States and its outlying
areas. This role is now expanding to include basic
map data as well as a family of general-purpose
maps. '

The national mapping program is initially focusing
on 11 categories of base-map data: reference sys-
tems, hypsography, hydrography, vegetative cover,
nonvegetative features, boundaries, transportation
systems, other manmade features, geodetic control
and survey monumentation, geographic names, and
orthophotographic imagery. Other map data of pub-
lic value may also be incorporated into the program;
under a cooperative agreement, the agency responsi-
ble for the data can arrange for the preparation of
maps or other forms suited to its needs.

The major products of the program are:

1. Digital data. The program’s goal is to supply the
base-map data in digital form for reasonable
areas of the country within 30 d of a request.

Orthophotos. Once a byproduct of the mapping
process, the orthophoto has become an im-
portant product in its own right. Orthophotos
are produced quickly and inexpensively and
provide a wealth of information not available
on line maps.

. Cartographic data. The availability of base data
in graphic form is being expanded. Reproduci-
bles that are feature separated as well as color
separated facilitate the preparation of special-
purpose maps. ,

4. Line map-s. The traditional multipurpose line map

is still an important tool and will continue to

be produced. In addition to the standard series

now available, new series at scales of 1 : 50,000

and 1 : 100,000 are being produced.

5°

00

274

 

Procedures for obtaining map products are given
in the section “How to Obtain Publications” in the
chapter on “US. Geological Survey Publications.”

MAPPING COORDINATION AND
REQUIREMENTS

The .USGS has the authority to coordinate feder-
ally funded domestic mapping activities. For an ef-
fective and economical response to national mapping
needs, the USGS coordinate‘s departm'entwide geo-
detic and mapping control surveys; identifies and
evaluates national mapping requirements; fosters
cooperative mapping, charting, and geodesy research
and development; and operates the National Carro-
graphic Information Center for ready exchange of
cartographic data gathered by government agen-
cies and some private organizations. During the past
year, this coordination included several noteworthy
projects:

1. Consulting with the Bureau of Land Management
to determine requirements and refine specifica-
tions for intermediate-scale maps to support
area studies and planning for programs of
national concern.

2. Assisting the Bureau of the Census with its spe-
cific cartographic requirements, such as the
full-line UTM grid and single-line road sym-
bols, to minimize the task of converting USGS
quadrangles into computer-compatible base
maps of road networks.

3. Confirming Soil Conservation Service (SCS) re-
quirements for an intermediate—scale base map.
According to a cost—sharing agreement, the
USGS will prepare planimetric bases for farm-
soil inventories for selected counties in each
State, and the SCS will add soil data and han-
dle publication.

4. Preparing 1:24,000-scale orthophotoquads for
SCS use as bases for soil—survey publications.
This eost—sharing program comprises 52 proj—
ects, or 1,700 orthophotoquads; an additional
1,600 orthophotoquads will be authorized
shortly.

TOPOGRAPHIC SURVEYS AND MAPPING

5. Producing a handbook on coastal zone mapping to
help States comply with the Coastal Zone Man-
agement Act of 1972. The handbook is a joint
effort of the USGS and NOAA‘and will be com-
pleted by December 1975.

6. Experimenting in combining National Ocean Sur-
vey bathymetric contour data with topographic
maps to produce a topographic-bathymetric
map series for coastal zones.

7. Cooperating with the U.S. Fish and Wildlife
Service on the preparation of aerial photo-
graph indexes needed for wetland inventories.

8. Documenting the need for a large-scale urban
map series. Private mapping firms prepared, to
USGS specifications, large-scale orthophoto-
graphic maps for Fort Wayne, Ind.; Charles:
ton, S.C.; Frederick, Md.; and San Francisco,
Calif.; the maps are now in the hands of users
who will provide feedback on applications. As
the various functions of city and county gov-
ernmental agencies become clearer, the USGS
will learn how they can be better served by
maps or related cartographic data.

9. Surveying the requirements of selected Federal
and State agencies, regional planning commis-
sions, universities, and county surveyors. Most
favor the full UTM grid on 71/2-min quad-
rangles, particularly where digitization of map
data is planned. Slope maps appear desirable
for areas prone to flooding, faults, and land-
slides. State highway departments generally
view a county map series as useful in‘ their
work, provided that the information can be
easily updated.

NATIONAL CARTOGRAPHIC INFORMATION
CENTER

The National Cartographic Information Center
(N 010) was established in 1974 to provide a central
repository for information on all U.S. cartographic
data—maps, charts, aerial photographs and space
images, geodetic control, and spatial data in digital
form. Cartographic data are acquired and held by
over 30 Federal agencies, all States, and innumerable
private organizations, but the data have not all been
easily accessible, and some duplication of effort has
resulted.

The NCIC plans to meet the increasing need for
cartographic data for resource exploration and de-
velopment, land and water-resource management,
land-use planning, and environmental protection. In
order to become a single service center for all carto-

 

27 5

graphic materials, the NCIC is inventorying the
holdings of various agencies and developing informa-
tion systems to make these data readily available,
initially through referral and ultimately through di-
rect handling of orders.

In August 1974, over 30 Federal agencies confer-
red with the USGS on the objectives of the NCIC.
During March and June 1975, the NCIC met with
agencies that have major holdings of aeriaLimages
to discuss automated indexing systems and arrange
for input. Data management agreements are being
pursued; some are already in effect, such as those
with the National Ocean Survey for consolidating
geodetic control information and with the EROS
Data Center on aerial imagery programs. .

The NCIC has formed a high-altitude photography
summary record system (HAP) ,that will rapidly
provide participating agencies with information on
existing and planned high-altitude photography.
Summary records describe the geographic extent and
general characteristics of aerial photographs that
are acquired, in progess, or planned by an agency.
The system output is computer-generated listings
and graphics showing the available coverage meet-
ing specified criteria. A standard set of graphics will
be published and distributed regularly by the NCIC;
users will also be able to request special searches.
Negotiations are underway with Federal agencies
for direct input to HAP. In fiscal year 1976, HAP
will be expanded to include aerial imagery holdings
and plans of State and local agencies and private
organizations.

System design is also well underway on the map
and chart information system. The data bank already
includes a complete listing of all USGS topographic
maps, both current and historic. These maps are also
being microfilmed on 35-mm black-and-white film.

. The computerized quadrangle map file will be ex-

panded to include maps and charts of various sources
and kinds covering any area of the United States.
The system is scheduled to be in operation by July
1976, when it will be possible to query the file from
remote terminals at several locations across the
country.

The Defense Mapping Agency digital terrain tapes
are now available from the NCIC. These tapes con-
tain data digitized from the 1:250,000-scale topo-
graphic map contours for the 48 contermino-us
States. The NCIC also offers status and ordering in-
formation for digital data on land use, census tracts,
political boundaries, hydrologic basis boundaries, and
Federal land ownership, which are being collected for
the USGS Land-Use Data and Analysis program.

276

The success of the NCIC depends largely on the
cooperative efforts of the organizations that collect,
produce, and distribute cartographic data. First re-
actions from 20 Federal agencies have been highly
favorable. The NCIC publishes a quarterly newslet-
ter, and a “User Guide” to NCIC services will be
available soon.

MAPPING ACCOMPLISHMENTS

Quadrangle map coverage of the Nation

General-purpose topographic quadrangle map cov-
erage at scales of 1 :24,000, 1 : 62,500, 1:63,360 (Alas-
ka), and 1:20,000 (Puerto Rico) is now available for
about 92.6 percent of the total area of the 50 States,
Puerto Rico, the US. Virgin Islands, Guam, and
American Samoa. Included in this coverage is about
3.8 percent of the total area, not yet published but
available as advance manuscript prints.

During fiscal year 1975, 1,468 maps were pub-
lished covering previously unmapped areas, equiva-
lent to about 2.3 percent of the area of the 50 States
and territories referred to above. In addition, 484
new maps at a scale of 1:24,000, equivalent to about
0.8 percent of the total area, were published to re-
place 15-min quadrangle maps (1:62,500 scale) that
did not meet present needs. Figure 6 shows the ex-
tent and. location of the current topographic map
coverage.

Map revision and maintenance

As maps become out of date, revision is necessary
to show changes in the terrain and changes and addi-
tions to manmade features, such as roads, buildings,
and reservoirs. During fiscal year 1975, 907 general-
purpose quadrangle maps of the 71/2-min series
(1:24,000 scale) were revised. Most of these revised
maps are in large metropolitan areas and their ex-
panding suburbs and in States that are completely
mapped in the 71/2-min series that have cooperative
programs for a regular updating. About 57 percent
of the 1,746 maps currently in the revision program
(fig. 7) are being updated by photorevision—a low-
cost rapid production method that relies primarily on
photointerpretation. Recent aerial photographs of
the areas to be revised are inspected, and changes in
cultural and other planimetric features are mapped
and printed in purple on the revised map.

An inspection program, started in fiscal year 1972,
has contributed substantially to reducing the revi-
sion backlog. During fiscal year 1975, 1,569 71/2-min
quadrangles were inspected, and 1,044 were found to
need revision. Those not needing revision are noted

 

GEOLOGICAL SURVEY RESEARCH 1975

on the sales indexes, and the inspection date appears
on the reprinted maps.

The maps in the revision program that are not
ph-otorevised will receive a more complete overhaul,
which will include a field check and revision of some
or all of the color-separation drawings.

In fiscal year 1975, approximately 1,280 general-
purpose quadrangle maps were reprinted to replen-
ish stock.

1:250,000-scale map series

The 48 conterminous States and Hawaii are com—
pletely covered by 473 topographic maps at
1:250,000 scale. Originally prepared as military edi-
tions by the Defense Mapping Agency (formerly the
US. Army Map Service), the series is now main-
tained by the USGS. Maps are revised in an average
8-yr cycle, and standard metropolitan statistical
areas are revised every 5 yr, provided that adequate
source materials are available. Figure 8 shows revi-
sions in progress on 1 : 250,000—scale maps.

Of the 153-sheet Alaska reconnaissance series, all
but a dozen have been replaced with standard maps
based on larger scale source materials and on new
photogrammetric compilations; these maps are part
of the US. 1:250,000 series. An active revision pro-

gram has been established to maintain the currency

of the Alaska series:

In cooperation with NOAA, a program to produce
topographic-bathymetric editions of 1:250,000-scale
maps of the coastal zones of the United States was
started in fiscal year 1974. The Beaufort, N.C., ex-
perimental quadrangle is the first joint edition; ele-
vations are shown in feet, and water depths are
shown in metres. Five additional maps in the series
are in progress: Appalachicola, Providence, Gaines-
ville, Tampa, and Plant City, Fla. Topographic-bathy-
metric editions will be prepared as bathymetric data
become available.

Maps in the 1:250,000-scale series are used by the
USGS as base copy for the preparation of the State
base-map series, the International Map of the World
series, and special small-scale maps such as the land-
use—land-cover series now in production. The
1:250,000—scale series has also been designated by
the Board on Geographic Names as a basic
reference for geographic nomenclature in Govern-
ment publications.

State base-map series

State base maps are published at scales of
1 : 500,000 and 1 : 1,000,000 for all States except Alas-

277 ’

TOPOGRAPHIC SURVEYS AND MAPPING

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ka. State base maps of Alaska are published at scales '
of 1:1,584,000, 1:2,500,000, 1:5,000,000, and 1:12,—
000,000. A State base map of Connecticut is also
available at a scale of 1 : 125,000. The maps are gen-
erally prepared in three editions—base, topographic,
and shaded relief—and show urban areas, major
communications routes, major hydrographic fea:
turos, and county boundaries. The series consists of
46 maps covering the 50 States and the District of
Columbia; 17 maps are in progress. Figure 9 shows
revision progress on the State base-map series.

National park map series

Special topographic maps have been prepared for
50 of the national parks, monuments, historic sites,
and other areas administered by the National Park
Service that are large enough to require separate
editions. They are usually made by combining the
existing quadrangle maps of the area into one map

 

sheet, but, occasionally, surveys are made covering
only the park area. Many of the maps are also avail-
able in a shaded-relief edition. Other parks, monu-
ments, and historic sites are shown on maps in the
general-purpose quadrangle series. New or revised
maps in preparation include:

Arches National Monument, Utah

Big Bend National Park, Tex.

Great Smoky Mountains National Park, N.C.-Tenn.
Mount Rainier National Park, Wash.

North Cascades National Park, Wash.

Point Reyes National Seashore, Calif.

New or revised maps published in fiscal year 1975
include:

Canyonlands National Park, Utah

Death Valley National Monument, Calif.-Nev.
Glacier National Park, Mont.

Mesa Verde National Park, Colo.

Mammoth Cave National Park, Ky.

Mount McKinley National Park, Alaska
Theodore Roosevelt National Park, N. Dak.

 

280

GEOLOGICAL SURVEY

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Small-scale map series

The International Map of the World (IMW) series
at a scale of 1:1,000,000 is part of an international
program to attain worldwide coverage at a uniform
scale and format. The maps are published in accord-
ance with technical agreements and specifications
adopted at UN. conferences in 1962 and 1964.

Thirty of the 54 IMW maps required to cover the
oonterminous United States and Hawaii have been
published. Twenty—one additional maps of the con-
terminous States and 13 maps of Alaska were pub-
lished by the Defense Mapping Agency Topographic
Center from 1955 to 1959 in a military series at a
121,000,000 scale. Although these maps do not meet
the IMW specifications in all respects, they are recog-
nized by the UN. Cartographic Office as provisional
editions in the IMW series (fig. 10).

Work in progress includes three new maps—An-
dreanofl’ Islands, Cold Bay, and Blue Ridge—and

' four revisions—Cascade Range, Hudson River, Lake
Erie, and Savannah. Four maps have been published
since June 30, 1974—Des Moines, Ozark Mountains,
Hawaii, and Attu Islands.

Orthophotographic products

Orthophotoquads are black-and-white photoimage
maps in 71/2-min-quadrangle format with little or no
cartographic treatment. There is increasing demand
for this product, either as an interim map in areas
unmapped at 1:24,000 scale or as a companion prod-
uct to a published line map. The goal for 1978 is
orthophotoquads for all areas of the conterminous
United States that are unmapped at 1:24,000 scale.
Orthophotoquads are also being prepared under cost-
sharing agreements with the Soil Conservation Serv-
ice, the Forest Service, the‘Bureau of Indian Affairs,
and the Bureau of Land Management and under co-
operative programs with several States. Approxi-
mately 4,000 orthophotoquads were prepared by the

 

 

TOPOGRAPHIC SURVEYS AND MAPPING

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FIGURE 10.—Status of publication of 1: 1,000,000-scale topographic maps. Work in progress is being done by the USGS.

USGS in fiscal year 1975; 10 percent of these will be l

lithoprinted, depending on projected distribution,
and the remainder will be reproduced by the diazo
process.

Orthophotomaps are color photoimage maps with
substantial cartographic treatment that have be-
come the standard 71/g-min maps for certain are-as
of the country where conventional topographic maps
cannot adequately portray featureless terrain. The
swamps of the Florida Everglades, the lake region of
northern Minnesota, and coastal areas of Louisiana
and Georgia are major orthophotomapping projects.
About 300 orthophotomaps are in the current
program.

Intermediate-scale map series

The need for map products between the 1124,000-
and 1:250,000-scale series led to an intermediate-

 

scale mapping program. Its goal is complete national
coverage with 1:100,000—scale topographic quad-
rangles and selected coverage with 1 : 50,000— and
1:100,000-sca1e county maps. Agreements with Fed—
eral and State agencies provide for the USGS to pro-
duce 195 30X60-min quadrangle maps at 1:100,000
scale. Agreements for county maps include 62 at
1 : 50,000 scale and 121 at 1 : 100,000 scale; a uniform
scale will be maintained within a State.

NATIONAL ATLAS

The National Atlas of the United States of Ameri-
ca, published in 1971, was compiled as a reference
and research tool for use by public ofl‘icials, business
and industrial organizations, libraries, educational
institutions, and scholars who seek information
about the United States. Preparation of the 431-page

282

volume involved the cooperation of more than 80
Federal agencies and bureaus, organizations, com-
mercial firms, and individual specialists. It contains
336 pages of multicolor maps and related informa-
tion and an index with more than 41,000 entries.
Twenty-eight new or revised separate sales sheets
are in preparation. The following individual map
sheets are available as separate sales items:
United States general
reference
Physiography and physio-
graphic divisions
Land-surface form
Classes of land-surface
form
Tectonic features (Alaska)
Tectonic features
(conterminous United

Distribution of principal
kinds of soils: orders,
suborders, and great
groups

Potential natural vegeta-
tion of Alaska and
Hawaii

Potential natural vegeta-
tion (conterminous
United States)

States) Population distribution,
Geology urban and rural: 1960,
Monthly average tem- 1970

perature Federal lands

. . Population trends:
Monthly minimum tem- .
changes, dens1ty, and
perature

urban-rural
Congressional districts for

the 91st Congress
Shaded relief (contermin-

ous United States)
Shaded relief (Alaska)
Monthly sunshine

PROGRAMS IN ANTARCTICA

The US. Antarctic Research Program is admin-
istered and funded by the Office of Polar Programs
of ‘the NSF. The USGS participates in this program
by administering the field-mapping operations, win-
terover Doppler research programs, and the carto-
graphic programs.

Surface water

Principal uses of water

Territorial growth

Major forest types

Annual sunshine, evapora-
tion, and solar radiation

 

Field operations

During the austral summer, R. D. Worcester and
M. C. Crutcher established precise positions by Geo-
ceiver observations at selected strain-rate sites in
support of the Ross Ice Shelf Project. The USGS
participated for the second year in the University of
Nebraska’s Antarctic program for measuring ice
thickness, movement, and structure over several
years.

E. G. Schirmacher and A. I. Malva-Gomes estab-
lished control for the Lindsey Islands map during
the Pine Island Bay expedition, which had been post-
poned from the previous summer. The ship returning
the men to Palmer Station encountered hazardous
ice conditions for a few days off the coast of Thur-
ston Island.

 

GEOLOGICAL SURVEY RESEARCH 1975

W. M. Voight conducted Doppler observations dur-
ing the austral summer to establish positions at Byrd
Station and Sip-1e Station, on the polar plateau at
Dome Charlie, and around M-cMurdo Station. Several
LC—130 cargo planes were damaged during support
operations at Dome Charlie, but no one was injured.

The two year-round projects conducted at Casey
and South Pole Stations continued. Experiments at
both sites are supporting ice movement, scintillation,
and polar-motion studies with Doppler satellite ob-
servations. R. J. Neif is wintering over at Casey Sta-
tion, having relieved D. L. Schneider. Nef’f operates
the, Geoceiver on inland traverses with the Australi-
an field survey parties to support the International
Antarctic Glaciological Program.

R. G. Boschert and ‘J. E. Serensen relieved
M. Y. Ellis and T. K. Meunier at the South Pole Sta-
tion. A year-round Doppler satellite base tracking
station is operated by USGS personnel. Results based
on several years of Doppler data collected at Pole
Station indicate that the ice is moving approximately
9 to 10 m/yr in the direction N. 43° W. New Pole
Station, first occupied this year, was located so that
it will eventually drift over the geographic South
Pole. The abandoned Pole Station was originally lo-
cated about 830 m downstream from the pole and is
now 1,000 m downstream. The men are also monitor-
ing the seismological equipment for the USGS Office
of Earthquake Studies.

Cartographic activities

In accordance with Resolution 3 of the Third Meet-
ing of the Scientific Committee on Antarctic Re-
search (SCAR) Working Group on Geodesy and Car-
tography, the USGS continues to supply published
materials and maps of Antarctica to SCAR member
nations. A collection of maps and related materials
from SCAR members are available through the Ant—
arctic SCAR Library at the N CIC (National Center,
STOP 507, Reston, Va. 22092).

The status of USGS mapping in Antarctica is
shown in figure 11. Compilation continues on 12
1:250,0-00-sca1e maps of the coast of Marie Byrd
Land and on a 1:500,000-scale sketch map of Palmer
Land at the base of the Antarctic Peninsula. Several
1:250,000-scale maps were approved for printing,
but the publication date has not been set. A special
large-scale map of McMurdo Station is being pre-
pared with both metric and conventional units for
use by contractors in planning utilities and other
construction.

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" "ENINSULA

TOPOGRAPHIC SURVEYS AND MAPPING 283

      
      
     
 

 

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Topographic with Reliel Shading STATUS OF MAPP|NG Topographic with Relief Shading

Planimetric Manuscripts 1:500.000 scale

Various scales
Sketch Maps with Reliet Shading
1500.000 scele

1:250,ooo scale by C] 1:250,ooo scale

US. Geological Survey

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D
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In Reproduction
1:1.ooo,oooe 112,188,800

Ross Ice Shell Planning Map

r'l
LJ

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111,000,000

FIGURE 11.—Index map of Antarctica, showing status of topographic mapping.

284

LANDSAT experiments

Investigations continue under the NASA—funded
project SR—149, “The Cartographic Applications of
LANDSAT Imagery in Polar Regions.” Several map
products were completed during this period: a com-
panion 1:1,000,000-sca1e IMW mosaic of the McMur—
do Sound region; 1:1,000,000-scale mosaics of Vic—
toria Land and of the Thurston Island-Jones Moun-
tains area; a single-scene map at 1:500,000 and
1:250,000 scales of the Dry Valley region; and a
1 : 500,000-scale mosaic of the Ellsworth Mountains.

LANDSAT images are being used to revise
1:250,000-sca1e maps and the 1 :10,000,000—scale map
of Antarctica published by the National Geographic
Society. LANDSAT imagery has also proved valu-
able in monitoring the movements of large icebergs
and ice islands and the seasonal changes in ice fronts
associated with Antarctic ice shelves and in the ice-
pack that surrounds the continent.

INTERNATIONAL COOPERATION

Mexico

The first product of the USGS-CETENAL (Co-
misién de Estudios del Territorio Nacional) agree-
ment for the exchange of information was viewed at

a joint meeting in Mexico City in July 1974. The

1:50,000—scale metric topographic map of the Rio
Grande Valley marks the beginning of joint map-
ping of U.S.—Mexico border areas. Another USGS-
CETENAL meeting was held in February 1975 in
Menlo Park, Calif., to discuss aerial photography,
geodetic control, and exchange of map products.

Pan American Institute of Geography and History (PAIGH)

The USGS continued to provide administrative and
staff support for the US. member of the Commission
on Cartography and for the chairman and US. mem-
ber of the Committee on Topographic Maps and
Aerophotogrammetry. Six USGS personnel are con-
tributing to PAIGH activities.

The US section of the Commission on Cartogra-
phy and the chairman of the US. National Section
held two meetings in Reston, Va., during the fiscal
year. In September 1974, they met to discuss the
results of the fifteenth meeting of the Directing
Council held in Mexico City. In March 197 5, they met
to consider actions taken by the authorities of
PAIGH at Caracas, Venezuela, regarding new proj-
ects and programs of the various commissions.

Color separates for the “Atlas of Volcanic Phe-
nomena” were delivered in July 1974 to the PAIGH

 

GEOLOGICAL SURVEY RESEARCH 1975

Secretary General in Mexico City. The atlas is an
active sales item in the United States, and PAIGH
plans to publish a Spanish edition for distribution
throughout Latin America.

Saudi Arabia

The USGS is continuing to assist the Ministry of
Petroleum and Mineral Resources of the Kingdom of
Saudi Arabia in its effort to increase the permanent
capacity for geological and resource investigations
and to direct the mining industry toward the best
possibilities for mineral exploration and develop-
ment. The fourth extension agreement with the Min-
istry was completed in June 1975 and approved by
the Director of the USGS. The agreement, covering
a 3-yr period starting July 10, 1975, was forwarded
to the Ministry for approval. In support of this pro-
gram, the USGS continues to assign personnel to
Saudi Arabia. In the latter part of 1974, R. C. Nixon
replaced K. S. McLean as a field surveys specialist,
and C. M. Robins replaced F. G. Lavery as a photo-
grammetric specialist.

RESEARCH AND DEVELOPMENT

FIELD SURVEYS
Inertial surveying

After more than 16,000 km of trial surveying by
the Defense Mapping Agency (DMA) with the Jeep—
mounted Position and Azimuth Determining System
(PADS), several government agencies recognized
that, by applying the system in closed traverses,
PADS can probably establish positions accurate
enough for public-land and map-control surveys.
Such applications are intended for the Auto-Sur-
veyor, a civilian version of PADS being developed by
Litton Systems, Inc., for the Bureau of Land Man-
agement (BLM). The Auto-Surveyor consists of an
inertial measuring unit, a digital processing unit, a
control and display unit, a power supply unit, and a
cassette recorder. With a battery and electrical
cables, the system weighs 150 kg and fills the passen-
ger space, behind the pilot and operator, of an FH—
1100 helicopter.

The innovation that makes an inertial navigation
system perform so accurately is the development of
the zero-velocity update procedure. The vehicle is
periodically brought to a standstill, and the system
automatically levels the platform to the local gravity
vector and analyzes the residual velocity values to
obtain correction terms. As the traverse continues,

TOPOGRAPHIC SURVEYS AND MAPPINGr

with periodic zero-velocity updates, the computer
accumulates information about and compensates for
systematic observational errors and the systematic
changes in the gravity field. Less accurate results are
obtained when the line has an abrupt change in
direction, such as a right-angle turn.

The accuracy of the Auto-Surveyor in a flat desert
environment (near Phoenix, Ariz.) was tested in
December 1974 by the BLM. A major part of the
test was trying different combinations of procedures,
3- or 5-min periods between landing or hovering
updates, over straight survey lines about 38 km long.
A preliminary evaluation of test data indicates a
high level of accuracy—standard deviations of 0.74,
0.71, and 1.00 m in latitude, longitude, and elevation,
respectively—and significantly improved accuracy
with 3-min updates. To obtain accuracies suitable
for map control, lines must be nearly straight, no
longer than 50 km, and double run. The average
travel time for one 38-km run was 30 min. Some
developmental work is needed to extract the highest
accuracy obtainable with the present hardware. For
USGS use, improved accuracy in vertical measure—
ments is necessary before the Auto-Surveyor can be
applied with full practicality.

A system that will provide ground profiles by
measurement from an aircraft, the Aerial Profiling
of Terrain System (APTS), is being developed by
the USGS and the Charles Stark Draper Laboratory,
Cambridge, Mass. The proposed APTS, to be carried
by a light single- or twin-engine plane, comprises:
(1) An inertial measuring unit to continuously de-
termine latitude, longitude, and elevation of the air-
craft; (2) a laser tracker unit to measure on posi-
tioned ground retrorefiectors for periodic updating
of the inertial system; (3) an imaging instrument
(TV or camera) to record the flight path; (4) a com—
puter to process and adjust the measurements and to
provide in-fiight guidance; and (5) a tape recorder
to store the profile data. The terrain profiling system
in operation is visualized as a powerful tool for flood
studies as well as for map-control surveys.

Geodetic data management agreement

The NOAA-USGS Memorandum of Understanding
of June 13, 1974, established joint policies and pro-
cedures for the exchange, maintenance, and distribu-
tion of geodetic control data. That agreement re-
affirms the mandate of the Federal Mapping Task
Force to establish a central file of geodetic data and
thus will improve service to the user by recognizing
the' National Geodetic Survey Information Center
(NGSIC) as the primary source for Federal geodetic

 

285

control data. The USGS is committed to transferring
all the geodetic data that it has acquired to NGSIC
by 1980. By this agreement, the USGS will provide
data on monumented, recoverable control points of
third-order accuracy or better that are connected to
the National Horizontal and Vertical Control Net-
works in a computer-compatible form specified by
the National Geodetic Survey (NGS).

To date, only the software for handling horizontal
control has been developed by the NGS. Present plans
are based on the 30-min quadrangle as the basic unit
area for storage and retrieval of data. The USGS is
modifying the NGS horizontal adjustment program
for use in preliminary evaluation of the data. The
NGS wants a good elevation on every horizontal sta-
tion, based on whatever data the USGS can supply,
including elevations scaled from published maps. In
contrast to horizontal control, even doubtful vertical
data are desired because repetitive leveling is in—
creasingly important in identifying and quantifying
surficial movement. USGS mapping centers have
undertaken pilot projects to discover problems, solu—
tions, and best methods. The NCIC is maintaining
files and supplying data on request during the trans-
fer period and warning against the use of old USGS
marks (not considered of third-order accuracy and
therefore not transfered to NGS responsibility) for
extending geodetic control. Also, the NCIC is investi-
gating ways and means of developing a system to
store, retrieve, and supply photogrammetric control
along with pertinent images.

Equipment improvements

Ground verification of mapworthy features is an
essential but painstaking and costly phase of topo-
graphic mapp-ing. In an effort to streamline these
field operations, a windowed van was custom fitted to
provide a comfortable and well-equipped mobile work
station. The vehicle is a 34-ton upgraded Chevy Van
with a wide sliding door on the side and double doors
at the rear. Sitting about 0.5 In higher than the
average car, the van affords a better view of the
terrain. The basic work station is a cut-down draft-
ing table with a built-in light box and drawers for
supplies, photographs, maps, and fieldsheets. The
desk chair is mounted on rails, with a variable-
position locking device. Special brackets inside and
outside the van conveniently store stadia rods, plane-
tables, and tools. First field trials of the custom van
won immediate approval, largely because on-the-spot
scribing is particularly helpful in revision surveys
and in annotating orthophoto bases.

286

Two USGS liquid-damped and two Keuffel and
Esser air-damped alidades were modified for mount-
ing directly on tripods. With the proper tripod, an
instrument height of about 2 m is possible. Tangent
screws were added to provide smooth slow motion in
the horizontal direction. Also, the optics of the Keuf—
fel and Esser alidade were modified so that the scale-
reading eyepiece is located beside the main telescope.
The increased instrument height provided by tripod
mounting raises the line of sight, and the effect of
heat waves is lessened. The instrumentman can take
readings from an erect position rather than a stoop-
ing positiOn. In use, the tripod alidade significantly
improves the efficiency of surveys for supplemental
vertical control while it maintains specified accuracy.

Special surveys and investigations

Monumentation and leveling observations were
completed on a test course established around the
National Center at Reston, Va. Eighteen stations
were set and leveled over, including one in the lobby
and one at the flagpole. During the year, the course
was used for evaluating several new instruments as
well as for training employees. Horizontal positions
will be established on the course this year. In addi-
tion, a station (Powell) has been set on the roof of
the National Center and will soon be tied into the
NGS triangulation network.

In five cases of boundary disputes (portions of the
Maine-New Hampshire boundary; the Dorchester
County-Wicomico County, Md., boundary; the Shen-
andoah National Park, Va., boundary; the Ever-
glades National Park, Fla., boundary; and the Louisi:
ana-Texas boundary), mapping expertise was called
on to supply surveyed positions or traverses, maps,
and court testimony.

Releveling in the Isleton, Calif., delta area indi-
cated an average of 6 to 9 cm subsidence with some
localized sinking of more than 30 cm since 1967. In
contrast, a low range of hills on the western edge of
the delta showed an uplift of 3 to 6 cm. A network of
new leveling and releveling was completed in the Raft
River Valley, Idaho, to serve as a monitor network
for the study of vertical crustal movement. The val-
ley is a fertile agricultural area where ground water
is being used for irrigation; it is also a potential geo-
thermal area. The releveled bench marks revealed
that up to 80 cm of subsidence has occurred in the
central part of the valley since 1958.

To monitor and control saline-water pumping for
mineral extraction at Searles Lake, Calif., a monitor
level network was recently established for the Con-
servation Division. Local crustal changes were indi-

 

GEOLOGICAL SURVEY RESEARCH 1975

cated in at least two separate areas around the lake.
Fifteen monitor level lines have now been estab-
lished across a number of western fault zones to
measure vertical movement. The releveling of the
Fairview Peak, Nev., monitor line showed vertical
creep of as much as 4 cm in a l—yr period.

PHOTOGRAMMETRY
Digital photogrammetry

The computer industry is offering increasingly
flexible software and hardware at a small fraction of
the cost a decade ago, a‘circumsta‘nce having con-
siderable effect on all aspects of civilian mapping.
Through digital techniques, it is conceivable that,
with a minimum of effort, mapmakers will be able to
respond to users’ needs in a matter of hours or days
rather than years.

The goal is to produce maps digitally at any scale
and in a variety of formats. To do so, cartographic
data must be converted to numerical data in ma-
chine-readable form. A single topographic quad-
rangle map contains more than 100 million discrete
bits of information, so that creating a digital map
data bank is forrnidably complex. Also, the data bank
must be designed to connect with other geographical-
ly related information and management systems.

With the assistance of the Rome Air Development
Center (RADC), Griffiss Air Force Base, N.Y., the
USGS conducted a pilot project to discover problems
in digitization—both deriving digital map data from
the stereomodel and generating graphics from the
data. The AS—11B—1 analytical plotter was used to
extract digital planimetric and terrain data from un-
conventional source material for the Estrella SW,
Ariz., quadrangle. An interactive system allowed
automatic plotting from magnetic tape with the Car-
tographic Digitizing Plotter, fast manual editing
with disk storage, and automatic tape correcting.
Additional smoothing of the data will be done auto-
matically with RADC’s Batch Processing System.
When data editing is completed, the updated tape
will be used to drive a first-order plotter and produce
the finish-quality color-separation negatives.

Map control from superwide-angle photographs

High-altitude superwide-angle photographs can be
used to provide pass points for wide-angle mapping
photographs and thereby reduce the amount of ver-
tical ground control needed. Early tests with 3,350-
and 6,700-m superwide—angle photographs failed to
meet vertical accuracy requirements and indicated
unsatisfactory point transfer. In a third trial with

TOPOGRAPHIC SURVEYS AND MAPPING

the 6,700—m photographs, acceptable results were ,

achieved after test procedures were changed: All un-
targeted points were drilled on the diapositive plates;
four readings were taken on fiducial and image
points, two normal and two with optics rotated 90°;
the block was adjusted as a whole; new camera cali-
bration data were used (made possible by improve-
ments in the USGS camera calibrator) ; radial lens
distortion was corrected by a newly devised grid
method; and independent afl‘ine transformations to
the calibrated fiducial mark coordinates were made
for each day’s measurements. The resultant rms
residuals were 1.1 m (3.6 ft) horizontally and 0.5 m
(1.6 ft) vertically. The 1:24,000-scale topographic
maps are now being compiled by using the photocon-
trol established by the refined solution.

Map control from high-altitude photographs

A study is underway to assess the practicality of
using high-altitude quad-centered photographs and
semianalytical aerotriangulation to establish verti-
cal control for normal production compilation with
low-altitude photographs. Horizontal and vertical
control points, previously selected on low-altitude
photographs, were pin-pricked on quad-centered
12,000-m photographs of the La Gloria, Tex., quad-
rangle and 10,800-m photographs of the Gillette,
Wyo., quadrangle. Observed 9c, y, and z coordinates
of all points were measured with a 05 Stereoplani-
graph and adjusted by four versions of a semiana-
lytical aerotriangulation program that treat the
error surface in turn as a plane, a sphere, a spheroid,
and a cylinder; 50 to 60 vertical control points-are
available in each quadrangle so that dispersion pat-
terns could be chosen for each assumed error sur-
face.

The adjustments were first computed with all
known elevations treated ' as control. Then only
known elevations for the selected control patterns
were used as control in the second series of adjust-
ments, and the rest of the points were used as test
points. The object was to find the error surface most
closely approximating the intrinsic errors of the
stereomodel. The lowest residuals were obtained
from the adjustment based on a spheroidal error sur-
face; for both study are-as, rms residuals were less
than 1.52 m (5.0 ft) at control points and averaged
1.60 m (5.25 ft) at test points. The error surfaces
were plotted with the Calcomp General Purpose Con-
touring Program and Perspective Drawing Software
System (Three-D). The graphic displays enabled
easy detection of major errors in original elevation
data.

 

287

Aerotriangulation of quadcentered photographs

The stepped-up production of orthophotoquads
calls for the aerotriangulation of hundreds of quad-
centered photographs each month. The unique grid
of camera positions allows a minimum of pass points
to serve many purposes—as model and flight ties
and as orthophoto scaling points. All points and point
transfers to the scanning plates are marked with a
Wild PUG. An efficient and accurate adjustment is
the simultaneous block adjustment of models, aver-
aging 2 s of central processing unit (CPU) time per
model on the IBM 370/155 computer. A fully ana-
lytical adjustment of refined comparator measure-
ments averaged 8 s of CPU time per plate. With
either mode, the rms horizontal errors of test points

varied from 1.5 to 3 m (5 to 10 ft).

Compilation from large-scale maps

A test was conducted to find out if large-scale engi-
neering plans can be efficiently incorporated into
standard 1:24,000-sca1e maps. A film positive of a
1 : 2,400-scale engineering plan of a portion of Lewis-
ton, Maine, was reduced to 1124,000 and projected
at 1:4,800 in a Kelsh plotter. Map detail was traced
mono-scopically and reduced to 1:24,000 through a
pantograph. Difficulties were encountered in extract-
ing the desired information because of the lack of
culture classification on the large-scale plans and the
fine detail of the contours, which had to be general-
ized for 1:24,000 portrayal. For comparison, a
stere-omodel of the Lewiston area, which covered
about 2.5 times the test area, was compiled by stand-
ard methods in about the same time required for
the monoscopic plot. On the basis of compilation tests
and limited field checking, large-scale engineering
plans cannot be used to advantage in compiling
1 : 24,000 topographic maps.

Model orientation with pocket calculators
S

Pocket-size programable calculators are being ap-
plied to model orientation with optical—train stereo-
plotters. For the relative orientation of models dur-
ing semianalytical aerotriangulation with a Wild A 7
or Kern PG 2, the analytical procedure requires only
one or two iterations, in comparison with the two to
six normally required. The technique is particularly
helpful for setting up stereomodels with rugged ter-
rain or large tilts. With camera orientation data
from fully analytical aerotriangulation, the calcu-
lator is programed to compute the Wild B 8 settings
for relative and absolute orientations. The resulting
stereomo-dels are correctly scaled, nearly clear of y
parallax, and nearly level.

288

Large-scale planimetric mapping

A largewscale (1 cm=24 m) planimetric map was
produced with the Kelsh stereoplotter. The area of
approximately 2.6 km2 (1 mi?) was compiled from
materials and control data acquired previously for
the Fort Wayne, Ind., large-scale orthophoto project.
The photographs were taken with a 152-mm f.l.
camera from 1,400 m. The manuscript was compiled
at model scale on a plotter with an optimum projec-
tion distance of 525 mm. Contours were not compiled,
but, given standard-accuracy supplemental vertical
control, 5-ft contours could be compiled easily. Copies
of the experimental map are being evaluated by the
Topographic Division and Fort Wayne officials.

Correcting radial lens distortion

A new method of correcting for radial lens distor-
tion was devised, in which corrections are applied
according to the grid location of the point rather
than the radial distance from the point of autocol—
limation. This method provides corrections for asym-
metrical and irregular distortions and for nonflatness
of the magazine platen.

The data for the corrections are obtained by meas-
uring collimator images on a series of film exposures
made with the camera on the calibrator at various
orientations. The distortions, or differences between
measured and true (calibrated) positions of the col-
limator images, are computer converted to con-tour
form. Then a distortion grid is derived from the
math model, typically a 5-mm grid for a 23-cm
square format. The x, y correction for a given point
is determined by interpolation between nearest grid
coordinates.

Automatic image correlation

A study was completed on the evaluation of den-
sity factors causing difficulties in the automatic cor-
relation of stereoimages. Transparencies of a low-
altitude stereopair were scanned with a J oyce-Loebl
microdensitometer, and the density profiles were
mathematically and visually compared. Density
peaks were visually correlated wherever possible
along corresponding density profiles. An arbitrary
origin was chosen (where parallax was zero), and
distances of peaks from the origin were measured
with the Bendix DataGrid digitizer; the differences
in measurements for matched peaks represented
parallax differences and were later used to calculate
elevation differences for constructing profiles.

The results indicate that many factors contribute

to losses of automatic correlation. The easily detect:

able difficulties are attributed to:

 

GEOLOGICAL SURVEY RESEARCH 1975

1. Objects that appear in only one photograph, like
the side of a building.

2. Large objects obstructing small objects on only
one photograph.

3. Sitautions in which a series of density peaks
represent density changes rather than changes
in elevation.

Other possible causes of difficulties are:

4. Slope of terrain.

5. Correlation of leafless trees with their shadows.

6. Problems with electrical noise when the signal-to-
noise ratio is low (i.e., very little density varia-
tion in the photograph), as in snow—covered or
heavily forested areas.

7. Objects that equal the scanning-spot size in one
photograph and are smaller than the spot size
in the other photograph and thereby produce
different density patterns.

8. Effect of light intensity on density variation.

The center of one photograph corresponds to
the edge of the adjacent photograph, and, as a
result, the density variation is larger in one
profile than in the other.

Panel photography by helicopter

A Hasselblad 70-min camera installed in the chin
of each USGS helicopter is being used to obtain im-
proved panel photographs. Since paneling rarely can
be timed for the panels to show on the mapping pho-
tographs used for aerotriangulation, each panel must
be photographed from a small aircraft so that the
surrounding ground features can be related to those
on the mapping photographs. The helicopter installa-
tion was designed to obtain a vertical photograph
having a relatively large format and a scale that can
be matched with that of the mapping photographs.
The pilot makes his run over the panel in a cardinal
direction if possible and usually 600 to 900 m above
terrain. Two frames are exposed for each panel to
yield a stereopair. In the field, a system of leapfrog-
ging the paneled points allows the pilot to fly without
passengers on one trip over any given panel and thus
makes it easy to climb to the required altitude. The
saving is in taking panel photographs while the crew
is on the spot, particularly when it is necessary to
take up the panel materials afterwards, as it is in
wilderness and other controlled areas. The helicopter
system is producing photographs that make identifi-
cation and correlation of paneled points easier and
cheaper than in the past. ’

TOPOGRAPHIC SURVEYS AND MAPPING

CARTOGRAPHY
San Juan's new metric map

The standard topographic maps of Puerto Rico and
the Virgin Islands are a mixture of 71/2-min quad-
rangles at 1:20,000 scale with metric contours and
71/;X6-min quadrangles at 1:24,000 scale with con-
tours in feet. The Puerto Rico maps measure 74x81
cm on the average, and thus only one can be printed
in a press run. As the maps are in need of extensive
revision, it was proposed to reformat all Puerto Rico
and Virgin Islands maps at 1 :20,000 scale in 45x60-
cm quadrangles (representing a ground area of
9X 12 km), a design which would enable printing
four at a time on the large five-color Harris press.
With other improvements in symbols and portrayal,
the new series would represent another step toward
promoting simplicity and economy for future maps.

Rather than map Puerto Rico in the extremities of
UTM zones 19 and 20, a UTM zone 19.5 was estab-
lished (central meridian at 66° longitude) for the
proposed series. The San Juan area was selected for
the experimental map because of its wide variety of
mapped features, although 1969 field data had to be
used. The grid format was constructed by a combina
tion of automatic plotting and hand plotting.
Archival negatives were reproduced and feature
separated as well as color separated. Many new sym-
bols and line weights were used that simplify draft-
ing and lend themselves to digitizing (for example,
dots were eliminated from spot and linear symbols).
Only two type styles (Souvenir and Univers) served
both the body and the margin of the map. The repro-
duction negatives were prepared by using mezzotint
screens to subdue or enhance features and to obtain
good color combinations. The maps were printed
four up on 44x 54-in paper and are being distributed
for evaluation.

Five-color interim revision maps

Interim-revision maps, constituting over 15 per-
cent of the USGS line maps prepared annually, are
normally printed in the five standard map colors plus
purple for added features. Printing in six colors is
inefficient with the new five-color press, since an ad-
ditional impression on another press is required.
Color schemes must be designed that will produce
the full range of map colors with no more than five
impressions.

To determine the feasibility of a five-color scheme
for interim-revision maps, the North Miami, Fla.,
71/g-min map was first contact photoprinted from
normal color-separation materials in the three pri-

 

289

mary colors—yellow, magenta, and cyan—plus black
and brown. Random-pattern mezzotint density
screens were used to blend colors and obtain desired
variations in the basic colors. The second experi-
mental printing was prepared by using biangle
screens and 120-1ine-screen tints with the five com-
bined reproduction negatives to achieve the desired
effect. The cost advantage of the five-color printing
scheme ranges from $244 per map printed on a two-
colo-r press to $64 per map printed on a five-color
press plus a two-color press for the additional color.
In addition, turnaround time in the plant is improved
2.5 times by printing interim—revision maps in five
colors rather than six colors with three passes
through two-color presses.

Land-use map overlays

Methods and formats for classifying and delineat-
ing land use are still under investigation. Personnel
in USGS mapping centers have been trained in the
compilation of land-use lines, and several experi-
mental projects were started. One approach is to
compile land-use information at 1:125,000 scale,
which will be reduced to 1:250,000 scale and regis-
tered with the standard map base and other bound-
ary overlays. Level 11 (Anderson and others, in
press) classification for quadrangles in Virginia and
Florida is in progress. Level III classification will be
attempted at 1:24,000 scale for 12 71Ag-min quad-
rangles in the Atlanta, Ga., area. In another project,
land-use information was compiled stereoscopically
and monoscopically at scales of 1:160,000 and
1: 125,000 for quadrangles in Arkansas.

An overlay, “Level I Land Use and Land Cover
Classification,” was prepared for the 1973 Hender-
son, Tex., 71/3-min quadrangle map. Five categories
are shown: urban and built-up land in light magenta,
agricultural land in yellow, forest land in green,
water in blue, and wetland in grey tint with swamp
symbol. The overlay was contract printed on clear
polyester film, which gives good transparency and
register. This type of overlay is being considered for
displaying land status and ownership, terrain slope,
and additional themes for the National Atlas.

Flood-plain maps

Sixteen watershed areas in St. Louis County, Mo.,
are being mapped as a joint venture with the Water
Resources Division (WRD) for the HUD flood-insur-
ance program. The project comprises 24 maps at
1:6,000 scale, which will be a combination of ortho-
p-hotoimagery and linework. The flood-prone areas
will be contoured at 3-ft intervals from 1,200-m

290

photographs. Profiles compiled at small intervals will
be used by the WRD to compute probable flood levels,
which will also be delineated on the maps.

50-State map

In response to manyrequests over the past few
years to graphically portray the 50 States of the
United States in correct pro-portion, position, and
relationship to one another, a 126,000,000-sca1e map
of the 50 States was prepared. The projection is a
wide-band Lambert conformal conic with standard
parallels at 37° and 65°. Highways, rivers, bound-
aries, railroads, cities, towns, and names were com-
piled from the National Atlas general reference
map (127,500,000) and global navigation charts
(1:5,000,000) and at two levels of content so that
maps at smaller scales can be derived. The map can
also serve as a base for future thematic editions. The
five-color 50-State map measures 92X144 cm
(36X56.6 in) and can be purchased from USGS map
sales offices.

Slope maps

Another method has evolved for making slope
maps. The contour negative is not projected but is
secured to a stationary glass above and in light con-
tact with film on an orbiting table. Exposure is made
with a remote pinpoint light source. There are sev-
eral advantages to this method: (1) The contour
negative is not reduced, (2) the film and contour
negative (or spread positive) are stud registered
rather than visually registered, (3) the precision in
line spreading and choking is greater, (4) the ten-
dency to fog with very wide chokes is diminished,
and (5) light intensity is greater, particularly im-
portant with the broader spreads and chokes.

1:100,000-scale maps

Several experimental projects are underway to
produce samples of 1:100,000-sca1e topographic
maps. The Healdsburg, Calif., map (northeast quar-
ter of the 1 :250,000 Santa Rosa map) was prepared
partly by enlarging the 1 : 125,000 San Francisco Bay
region maps and updating on the basis of 1972 U—2
high-altitude photographs; eight 71/2-min quad-
rangles, reduced and mosaicked, completed the map.
Color-separation plates were designed for flexible
reproduction; the contours and land lines were
scribed without breaks to facilitate digitizing. Metric
equivalents are shown in red for all spot elevations.

The Watford City, N. Dak., map (southeast quar-

ter of the 1 :250,000 Watford City map) is in prepara-.

tion. The 32 71/2-min quadrangles covering the area

 

GEOLOGICAL SURVEY RESEARCH 1975

were reduced to 1:100,000 scale and mosaicked.
Metric contours will be interpolated.

Digital cartography

Converting cartographic data—point, linear, and
areal—to digital data can be approached in several
ways. Experiments started last year in contour digit-
izing by automated line-following proved the capa-
bility of the i/o Metrics Sweepnik digitizer. A com-
puter-controlled laser beam digitized land-use bound-
aries at 1 : 24,000 scale from four experimental Fred-
ericksburg, Va., overlays, with readings recorded
every 250 ,im (the instrument is capable of 5mm
increments). The same device is also‘used to plot
from digital data by exposing film with the laser.
More experiments with the Sweepnik are in progress,
including the compilation of additional land-use
plates at scales of 1:125,000 and 1:250,000 for the
Land-Use Data and Analysis program and contour
and drainage plates at 1:24,000 scale for the Geo-
logic Division coal resources program.

Preliminary feasibility studies with digitizers
that scan with a photodiode linear array (push-
broom) show promise for highly automated carto-
graphic applications. As the pushbroom scans the
line copy, the intersections (line positions) are re-
corded. The advantages of this type of device over
the line-following device are (1) three to four times
faster digitization of a quadrangle; (2) virtually
automatic operation (a line-follower requires an at-
tendant to insure continuous operation) ; (3) batch-
process computer editing rather than interactive
‘manual editing; and (4) draft-quality copy input
rather than finish-quality input.

‘ The USGS recently purchased a computer-con-
trolled automated drafting system (model 1232)
from Gerber Scientific Instruments, Hartford, Conn.
The system offers high-precision (25 am) low-speed
drafting (up to 9.5 cm/s) and the capability of ink-
ing or scribing on a drafting surface or exposing on
photographic film. The plotter is controlled by a
Hewlett-Packard 2100A minicomputer. The 1.2X1.5-
m (4X5 ft) flatbed easily handles extra-large base
sheets for State and regional maps. The system is
now producing high-accuracy grids for hardware

calibration, low-frequency gratings for generating

orthophotos, line screens for cartographic and print-
ing applications, and computer-generated projections
for special projects. Examples are the Albers equal-
area and Lambert conformal conic projections of off-
shore areas under study by the Geologic Division,
plotted from control and data tapes generated by
Version IV of the Cartographic Automatic Mapping

TOPOGRAPHIC SURVEYS AND MAPPING

program now stored on the USGS computer. Com-
puter programs have been written for generating
and plotting base sheets and orthophotoquad grati-
cules and grids with the Gerber system.

The digital orthophoto system (DOS) will produce
digital profile information from a stereoscopic model,
store the information on magnetic tape, and use the
information off-line to control the photographic unit
that produces the orthophoto. The electronic units
are designed with the flexibility to adapt to several
types of profiling and exposing units. DOS comprises
three subsystems:

1. The prototype of a profiling device is being built
to attach to a Kelsh or ER—55 for translating
the platen in z and the guide-rail carriagein
x, y under servo control. A prototype device for
the Kern PG 2 has been tested.

2. The electronic subsystem consists of a profile re-
cording assembly (magnetic tape) now being
tested and a playback or scanning assembly.

3. The orthophoto output instrument consists of a
projector equipped with a three-axis servo sys-
tem for off—line exposure of orthophotos.

First tests of the complete system will consist of
profiling with a 05 Stereoplanigraph and scanning
and exposing with a GZ 1 Orthoprojector.

Orthophoto systems

The USGS is evaluating orthophoto systems for
standard quadrangle mapping. Tests with the
Gestalt Photo Mapper GPM—Z, Galileo-Santoni Ortho
Simplex, Wild AVIOPLAN, ICOS, Gigas—Zeiss GZ 1,
Danko-Arlington K—320, Wild PP 08, and Jenoptik
Orthophot B have been completed. Additional tests
are planned with OLOPS at the DMA, the Kern OP 2
Orthoprojector, and the Matra SFOM—910. Steps
have been taken to purchase the PP 08, Orthophot B,
and GPM—2. A GZ 1 acquired from the DMA will be
adapted for off-line seaming under control of a
USGS-designated electronic unit. USGS Orthophoto-
scopes are continually ' being improved; variable
transformers enable more precise light control dur-
ing exposure, and adhesive is replacing vacuum units
for holding the film.

Orthophoto scan masks

Masking techniques were applied to the problem of
scan lines on orthophotos. The Gerber plotter was
used to construct a 5-mm (scan width) grating, from
which two masks were prepared, one having alter-
nating clear and opaque 5-mm bars and the other
having the reverse. In orthophoto production, each

 

291

mask is stud registered over the film; the first ex-
posure is made through the open bars of mask 1, and
then the operation is repeated with mask 2 until the
entire film is exposed. The fact that the first trial
resulted in a simulated orthophoto with uniform-
width scan lines suggests that these lines could be
eliminated. The next step is to prepare new masks of
different dimensions.

Orthophoto image quality

It is desirable to have continuous image tone from
one quadrangle to the next throughout an orthopho-
toquad project. Thus, density levels and ranges for
photographic products must be planned in advance
for the complete project. Project planning is based
on the principle that the output density range and
level for each item remain proportional to the same
parameters measured on a sample of the input to the
system. Achieving tone match between items by
project planning may produce one or more orthopho-
toquads of less-than-satisfactory quality-and usabili-
ty. An example is the effect on low—density-range
items in a high-density-range project where item
contrast is increased very little or even decreased in
the end product. In this situation, a deviation from
the project plan is warranted to achieve the more
desirable product.

Planning the image quality for orthophotoquad
projects has been programed for the computer. An
adjustment in contrast is based on a parabolic func-
tion derived by the program to fit product specifica-
tions. The amount of adjustment varies with the
item: the lowest range item receives the largest
boost in contrast, and the highest range item re-
ceives little or no adjustment. The prototype pro-
gram is being used by the Western Mapping Center
with encouraging results.

Large-scale orthophotographic maps

Four contract urban mapping projects started last
year are nearly completed, and large—scale orthopho-
tographic maps will soon be in the hands of users to
determine their suitability for dealing with urban
problems. The USGS has served as technical advisor
and monitor, with the objective of developing stand-
ards for urban mapping. The projects are in various
stages of completion:

1. Fort Wayne, Ind. (10w, rolling topography and
180,000 population)—440 1:2,400-scale ortho-
photographic maps covering 570 km2 are com-
pleted and being used for city and county
projects.

292

2. Charleston, SC. (coastal city with relatively flat
topography and 75,000 population)——590
1:2,400-scale orthophotographic maps covering
1,080 km2 are 80 percent complete.

3. San Francisco, Calif. (coastal city with wide
range of topography and 700,000 population) —
Orthophotographic maps of 145 km2 at 1 : 6,000
scale and of selected areas at scales of 1:2,400
and 1: 1,200 are 85 percent complete.

4. Frederick, Md. (rolling topography with 25,000
population)—64 1:2,400-scale orthophoto-
graphic maps of 160 km2 are 90 percent
complete.

Private mapping firms were further sampled in a
project to determine their capabilities for orthopho-
tomapping urban areas with considerable relief. Six
firms having different instrumentation prepared five
1:2,400-scale orthophotos from 1,800-m, 153-mm fl.
and 3,600-m, 305-mm f.1. photographs of Ambridge,
Pa. (120-m relief), and from 1,200-m, 153-mm f.1.
photographs of Jackson, Mo. (30-m relief). The or-
thophotos were prepared with the Matra SFOM,
Zeiss Ortho 3, Kelsh K—320, J enoptic Orthophot,
Gestalt Photo Mapper GPM 1, and Wild PP 08. Each
orthophoto was tested for relative accuracy, the dif-
ference between orthophoto and stereomodel coordi-
nates at 35 test points. The resulting accuracies were
considered acceptable for an orthophoto of rugged
terrain, but it was significant that the results did
not favor any one firm. The 153—mm photographs
produced better resolution than the 305-mm photo-
graphs; however, they required more careful scan-
ning. The fact that the orthophotos made from 305-
mm photographs had fewer image mismatches in
rugged terrain indicates that the angle of projection
is more favorable with 305-mm photographs than
with 153-mm photographs.

 

GEOLOGICAL SURVEY RESEARCH 1975

Experimental orthophoto products

Six 1110,000-sca1e orthophotoquads of the Sapelo
Island research project covering the Doboy Sound,
Ga, 71/3-min quadrangle were completed. The coastal
wetlands were interpreted from color-infrared photo-
graphs and classified according to major plant spe-
cies associations. The annotated orthophotoquads are
available as oz-alid paper prints.

Two orthophotoquads and companion line maps at
1 : 125,000 scale are being prepared for the Connecti-
cut Valley urban area study. The 99 71A;-min ortho-
photoquads of the Connecticut Valley will be reduced
to a scale of 1:80,000 and mosaicked onto control
bases. The mosaics will then be reduced to 1: 125,000
scale and combined with the collar. The line maps
will be prepared from the State base map for the
southern map and from published quadrangle maps
for the northern map. The maps will bear minimal
name and collar information.

Three experimental color orthophotoquads of the
Tioga, N .Y., area were prepared from 1280,000-scale
153-mm F.L. color photographs. The diapositives
were made by Earthsat Corporation, Washington,
DC, and the color orthophotos were made by Geo-
metric Systems, Inc., Kirkwood, N.Y., with the J en-
op‘tic Orthophot. The resulting color balance was
poor, characteristic of color film exposed at high
altitudes.

Dry Valley, Antarctica, is being mapped with
1:50,000-scale orthophotoquads with 50-m contours.
Vast snowfields combined with sharp jagged relief
caused loss of._the stereoview and unavoidable breaks
in the scans. In many photographs, the density range
is extremely low but graded across the exposure, so
that density matching in mosaicking was nearly im-
possible. The mosaics of 1:35,000-sca1e prints were
retouched before reduction to 1 : 50,000 scale.

COMPUTER TECHNOLOGY

With its scientists engaged in research into every
existing and potential source of energy, the USGS is
increasingly charged with providing direction to both
Government and industry in all phases of energy—
related exploration, development, and production.
Concomitantly, USGS requirements for increased
computational capacity accelerated in fiscal year
1975. This growth pattern was typified by a transi-
tion from rudimentary batch-processing techniques
to more sophisticated interactive processing meth-
ods, using time-sharing systems, and the use of data-
base-management software packages. The Computer
Center Division (CCD) continued its expansion of
computation facilities to meet the needs of the
USGS’s scientific community. Future expansion was
formally addressed in a comprehensive planning
document, “The USGS Automatic Data Processing
Management Plan,” that identified requirements for
a 5-yr period (1976—80) .

RESTON COMPUTER SYSTEM

During fiscal year 1975, the bulk of USGS batch-
processing requirements was met by the IBM
370/155 computer system located in the National
Center at Reston, Va. The system accommodated the
batch requirements of local users, as well as those of
the remote batch-processing sites throughout the
United States. Action was taken to acquire and in-
stall a second IBM 37 0/ 155 when analysis predicted
saturation of the single system by July 1975. The two
central processing units will be identically configured
and possess equal memory capacity (4 million bytes
each). The planned configuration will ensure that
either processor could execute any current or future
program designed to run on the existing system. A
software load-leveling technique designed to balance
the processing load on each processor is being de-
veloped. In case of a processor failure, the remaining
processor will have the capability to assume the full
workload, albeit at a reduced throughput rate. The
two-computer configuration became operational in
September 1975.

 

The second IBM 370/155 is an interim computer
system, as was the initial system. The combined
capacity of the two computers will experience satura-
tion late in fiscal year 1976. Accordingly, the CCD
plans to procure a larger computer system to replace
the two IBM 370/ 155 computers.

TIME-SHARING SYSTEMS

To provide automatic data-processing support to
its energy program and related activities, the USGS
plans to procure three fully compatible time-sharing-
oriented computers to be used in Denver, 0010.; Men-
lo Park, Calif.; and Reston, Va. All three computers
will be accessed by numerous terminals. Sixteen large
data bases will be maintained on the computers.
Image-manipulation techniques using CRT graphic
devices and minicomputers monitoring scientific in-
strumentation will be used in support of scientific
computations.

DATA COMMUNICATIONS

Expanding requirements

Remote processing of data by an expanding data-
communications network continued to increase dur-
ing 1975. Approximately 70 terminals are connected
to National Center computers for remote job-entry
processing of batch—oriented tasks, an increase of
over 30 percent from 1974. The greatest increase was
realized in the technique of interactive processing,
where keyboard and CRT terminals provide the fa-
cility for accessing data bases, retrieving informa-
tion, executing computational algorithms, or creat-
ing computer programs in a conversational mode
with computers. Nearly 140 interactive terminals
are currently installed throughout the United
States for use by USGS scientists.

Dedicated network

The planned acquisition of three compatible time-
sharing computers for Menlo Park, Denver, and Res-

293

294

ton will generate a further increase in datacommuni-
cations traffic within the USGS. A study is currently
in progress to determine the parameters and cost of
a dedicated USGS network to efficiently accommo-
date data-communications requirements from 1976
to 1980. Planning inputs forecast nearly 600 termi-
nals in use by 1980, with a 100/500 split of remote
job-entry versus interactive processing. The planned
network will make use of the most current data-com-
munications technology and will be modular in
concept.

Problem diagnosis

The CCD has developed and incorporated into the
data-communications control program a software
routine that isolates communications problems. The
routine determines whether the problem is associated
with remote terminal hardware or with the com-
munications line and thereby reduces the time re-
quired for problem solving. The routine also incor-
porates an automatic disconnect feature to prevent
overloading of data-communication ports during
periods of excessive line problems.

DATA-BASE MANAGEMENT SYSTEM

The USGS has procured System 2000, a general-
purpose data-base management system. The basic
system 2000 provides the user with a comprehensive
set of data-base management capabilities, including
the ability to define new data bases, modify the defi-
nition of existing data bases, and retrieve and update
values in these data bases.

System 2000 was installed in the fall of 1974 and
is currently being used for the Ground-Water Site
Inventory System by the Water Resources Division.
Other divisions within the USGS are planning and
designing systems to be implemented by using the
flexible power of System 2000.

 

GEOLOGICAL SURVEY RESEARCH 1975

NEW SOFTWARE SUPPORT

Significant enhancements were made to the control
program of the IBM 370/155 in the fall of 1974.
Analysis of performance-measurement information
revealed that one routine of this program consumed
an exorbitant amount of central processing unit
(CPU) time. By modifying this routine, a better
than threefold reduction in CPU time was realized,
and an additional 4 h of available time was gained for
user applications. This enhancement forestalled the
saturation of the single IBM 370/155 by nearly a
year.

NEW FACILITIES

Rolla, Missouri

A Systems Engineering Laboratories, Inc., model
86 computer system was installed in March 1975.
This system replaced the IBM 360/20 computer ter-
minal and provides more efficient and flexible support
for the Midcontinent Mapping Center. The computer
system can operate as a computer terminal to the
Reston IBM 370/ 155 complex as well as concurrently
provide local computational support. This increased
support enables the implementation of new methods
of analytical aerotriangulation and will encourage
investigations into new computer applications for
more efficient operations.

Sioux Falls, South Dakota

A contract has been awarded for the installation
of a Burroughs Corporation B 6700 computer system
at the EROS Data Center. Installation was accom-
plished in September 1975. The system will replace
the existing IBM 360/30 and will continue the sup-
port needed to (1) catalog the data of the ERS pro-
gram and ongoing aircraft photography programs;
(2) answer requests and fill orders from the public;
and (3) schedule the operation of the EROS Data
Center. In addition, the system will support new
applications in digital image processing and analysis.

U.S. GEOLOGICAL SURVEY PUBLICATIONS

PUBLICATIONS PROGRAM
Books and maps

Results of research and investigations by the
USGS are made available to the public through pro-
fessional papers, bulletins, water-supply papers, cir-
culars, miscellaneous reports, and several map and
atlas series, most of which are published by the
USGS. Of these reports, books are printed by the
Government Printing Ofiice, and maps are printed by
the USGS; both books and maps are sold by the
USGS.

All books, maps other than topographic quadrangle
maps, and related USGS publications are listed in
the catalog “Publications of the Geological Survey,
187 9—1961” and “Publications of the Geological Sur-

vey, 1962—1970” and in yearly supplements, available

on request, that keep the catalogs up to date.

New publications, including topographic quad-
rangle maps, are announced monthly in “New Publi-
cations of the Geological Survey.” A free subscrip-
tion to this list may be obtained on application to the
U.S. Geological Survey, 329 National Center, Res-
ton, VA 22092.

State list of publications on hydrology and geology

“Geologic and Water-Supply Reports and Maps,
[State],” a series of booklets, provides a ready refer-
ence to these publications on a State basis. The book-
lets also list libraries in the subject State where
USGS reports and maps may be consulted; these
booklets are available free on request to the USGS.

Surface-water and quality-of-water records

Beginning with the 1961 water year, surface-water
records have been released on a State-boundary basis
in separate annual reports entitled “Water Resources
Data for [State]: Part 1, Surface Water Records.”
The records will also be published in the USGS series
of water~suprply papers at 5-yr intervals. The first
group of “Surface Water Supply” papers covers the
water years 1961—65.

Publication of quality-of-water records began in
the annual State series in 1964 as “Water Resources

 

Data for [State]: Part 2, Water Quality Records.”
The annual publication in the USGS water—supply
papers of “Quality of Surface Water of the United
States” by drainage basins has been continued. Dis-
tribution of the State water-resource data, Parts 1
and 2, is limited and primarily for local needs. These
reports are free on request to Water Resources Divi-
sion district offices (listed on p. 323) in areas for
which records are needed.

Indexes, by drainage basins, of surface-water rec-
ords to September 30, 1970, are published 'in the
USGS series of circu’rars, issues of which are free on
application to the Branch of Distribution, U.S. Geo-
logical Surveg, 1200 South Eads Street, Arlington,
VA 22202. These indexes list all streamflow and
reservoir stations for which records have been pub-
lished in USGS reports.

State water-resource investigations folders ~

A series of folders entitled “Water-Resources In-
vestigations in [State]” is a project of the Water
Resources Division to inform the public about its
current program in the 50 States and Puerto Rico,
the U.S. Virgin Islands, Guam, and American Samoa.
As the programs change, the folders are revised. The
folders are available free on request to the U.S.
Geological Survey, 435 National Center, Reston, VA
22092, or to the Water Resources Division district
offices listed on page 323.

Open-file reports

Open-file reports, which consist of manuscript re-
ports, maps, and other preliminary material, are
made available for public consultation and use. Ar-
rangements can generally be made to reproduce them
at private expense. The date of release and places of
availability for consultation are given in news re-
leases or other forms of public announcement. Since
May 1974, all reports and maps released only in the
open files have been listed monthly in “New Publica-
tions of the Geological Survey.” For reports issued
before this date, alisting has been published annually
in the circular series. Most open-file reports are
placed in one or more of the three USGS libraries:

.295

296

950 National Center, Reston, Va; Box 25046, Fed-
eral Center, Denver, Colo.; and 345 Middlefield Road,
Menlo Park, Calif. Other depositories may include
one or more of the USGS offices listed on page 318
and interested State agencies. Many open-file reports
are superseded later by formally printed publications.

Journal of Research of the U.S. Geological Survey

The “Journal of Research of the U.S. Geological
Survey” is a bimonthly periodical designed to pro-
vide relatively rapid publication of short scientific
papers by USGS personnel. It replaces the short-
papers chapters of the annual “Geological Survey Re-
search” series of professional papers, issued from
1960 through 1972.

Earthquake Information Bulletin

The “Earthquake Information Bulletin” is pub-
lished bimonthly by the USGS to provide informa-
tion on earthquakes and seismological activities of
interest to both general and specialized readers. It
also lists pertinent publications and selected future
professional meetings of Earth-science groups.

PUBLICATIONS ISSUED

Duzfimgifiscallyml'mmemmwfimfl WI
mpsmmmmmmemm;mmes,asfidflwszv '

 

 

Kind of map printed .1975

Topographic ._---_....____.._._ _____ 4,532

(Geologic and hydrologic ________________ 366

Maps for inclusion in book reports _______ 42
Miscellaneous ,(includin’glmaps Liorr‘mfller l

agencies ,_____.___________-____.___-__ _ i1‘6

Total .. ______________________ 4:956

 

In addition, 6 issues of the “Journal of Research”
‘uomprising about 752,280 copies, 6 issues of the 3
“Earthquake Information Bulletin” comprising about ,
mmmmmnusmmmmmmam!

mmmwmmwmmummi
mflfimoupfiesafl’mpsaufllhwkmhmmw
hfieMkWWJfiWflmm,’
ummmfimpmfimfindlulimgmmm‘
maps, wane W. Amtmiinmtdly 31$ miilliun t
mm were sum, and 8mm was When the
Miscellaneous ammonium US. Treasury. ,

The USGS also distributed 384,925 "copies of tech
nical book reports, without charge and for official
use, and 1,475,600 copies of booklets, free of charge,
chiefly to the general 'public'; 289,550 copies of the
monthly publications announcements and 108,500
copies of a sheet showing topographic map symbols
were sent out.

 

 

GEOLOGICAL SURVEY RESEARCH 1975

The total distribution resulted from receipt of
782,475 individual orders. The following table com-
pares USGS map and book distribution (including
booklets but excluding map-symbol sheets and
monthly announcements) during fiscal years 1974
and 1975:

Number of maps and books distributed

 

 

 

Fiscal year Change

Distribution points 1974 197 6 c555)-
Eastern (Arlington, Va.) __ 6,010,586 6,499,087 +8
Central (Denver, Colo.) ____ 4,598,479 4,938,330 +7
Alaska (Fairbanks) _______ 123,317 129,949 +5
12 other USGS offices ______ 794,435 857,234 +7
Total _________________ 11,526,817 12,424,600 +7

 

HOW TO OBTAIN PUBLICATIONS

OVER THE COUNTER

Book reports

Book reports (professional papers, bulletins, wa-
ter-supply papers, “Topographic Instructions,”
“Techniques of Water-Resources Investigations,”
certain leaflets in bulk quantity, and some miscel-
laneous reports) “can be purchased from the Branch
(of Distrtbutz’om, ILS. Wow/oat Stormy, 1200 South
Emisflbnwtdnzlongtm VA.22m,andfmflne
USGS Public Inquiries ’Oifioes Histmi on page 322
(authorized agents of the Superintendent of

E Documents)-

Some book publications that can no longer be ob-

; tained from the Superintendent of Documents are
; available for pmhase from the above aim-them
" agents of the Superintendent of Documents.

fmpsand charts

Maps and charts may be purchased at the follow-
WWW:
moo South W‘s Sit... AW Va.
9% Pimp Sit, Bambi, Mo.
Bum 25286, Wall 015mm,, Denver, Colo.
345W MMM (Mitt
llliromn 4141, W Whigs, we Went Ninth
$12,, llama, when
311%) lFiirslt Ave, William, Alaska
Public {inquiries (Offices listed tom page
322
USGS [maps are also sold by some 1,500 tomnmer—
cial dealers throughout the United States. Prices
charged are generally higher than those charged by
USGS ofl'ices. '
Indexes showing topographic maps published for
each State, Puerto Rico, the U.S. Virgin Islands,

U.S. GEOLOGICAL SURVEY PUBLICATIONS

Guam, American Samoa, and Antarctica are avail-
able free on request. Publication of revised indexes
to topographic mapping is announced in the monthly
“New Publications of the Geological Survey.” Each
index also lists special and U.S. maps, as well as
USGS offices and commercial dealers from which
maps may be purchased.

Maps, charts, folios, and atlases that are out of
print can no longer be obtained from any official
source. These may be consulted at many libraries,
and some can be purchased from secondhand-book
dealers.

BY MAIL

Book reports

Technical book reports, certain leaflets in bulk
quantity, and some. miscellaneous reports can be
ordered from the Branch of Distribution, ‘U.S. Geo-
logical Survey, 1200 South Eads Street, Arlington,
VA 22202. Prepayment is required and should be
made by check or money order payable to the U.S.
Geological Survey. Postage stamps are not accepted;
please do not send cash. On orders of 100 copies or
more of the same report to the same address, a 25-
percent discount is allowed. Circulars and some mis-
cellaneous reports may be obtained free from this
Branch.

Maps and charts

Maps and charts, including folios and hydrologic
atlases, are sold by the USGS. Address orders to
Branch of Distribution, U.S. Geological Survey,
1200 South Eads Street, Arlington, VA 22202, for
maps of areas east of the Mississippi River, includ-
ing Minnesota, Puerto Rico and the U.S. Virgin
Islands, and to Branch of Distribution, U.S. Geologi-
cal Survey, P0. 302: 25286, Federal Center, Denver,
CO 80225, for maps of areas west of the Mississippi,
including Alaska, Hawaii, Louisiana, Guam, and
American Samoa. Residents of Alaska may also or-
der maps of their State from the Alaska Distribu-
tion Section, U.S. Geological Survey, 310 First
Avenue, Fairbanks, AK 99701.

Prepayment is required. Remittances should be by
check or money order payable to the U.S. Geological
Survey. On an order amounting to $300 or more at
the list price, a 30-percent discount is allowed. Prices
are quoted in lists of publications and in indexes to
topographic mapping for individual States. Prices in-
clude the cost of surface transportation.

 

297

Journal of Research of the U.S. Geological Survey and
Earthquake Information Bulletin

Subscriptions to the “Journal of Research of the
U.S. Geological Survey” and the “Earthquake In-
formation Bulletin” are by application to the Super-
intendent of Documents, Government Printing Of-
fice, Washington, DC 20402. Payment is by check
payable to the Superintendent of Documents or by
charge to your deposit account number. Single issues
may also be purchased from the Superintendent of
Documents.

Advance material from mapping

Advance material available from current topo-
graphic mapping is indicated on individual State
index maps, which are issued quarterly. This materi-
al, which includes such items as aerial photography,
geodetic control data, and maps in'various stages
of preparation and editing, is available for purchase.
Ordering information is contained in the text of the
indexes. Requests for the indexes or inquiries con-
cerning the availability of advance material should
be directed to the National Cartographic Informa-
tion Center, U.S. Geological Survey, 507 National
Center, Reston, VA 22092.

EROS Data Center materials

USGS aerial photography, NASA aircraft pho-
tography and imagery, LANDSAT (formerly called
ERTS) imagery, and Skylab imagery and photogra-
phy are sold by the USGS, as are copies of the pho-
tography and imagery produced on 16-mm browse
film, which are designed for prepurchase evaluation.
LANDSAT Standard Catalogs are also sold. Ad-
dress requests for price list, additional information,
and orders to EROS Data Center, U.S. Geological
Survey, Sioux Falls, SD 57198. Prepayment is re-
quired for orders. Remittances should be made pay-
able to the U.S. Geological Survey.

National Technical lntormation Service

Some USGS reports, including computer pro-
grams. data and information supplemental to map
or book publications, and data files, are released
through the National Technical Information Service
(NTIS). These reports, available either in paper
copies or in microfiche or sometimes on magnetic
tapes, can be purchased only from National Techni-
cal Information Service, U.S. Department of Com-
merce, Springfield, VA 22161. USGS reports that
are released through NTIS, together with their
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GEOLOGICAL SURVEY RESEARCH 1975

 

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1975, Adjustment of'

 

305

Roberts,A.A.,Friedman,Irvimg,Donovan,T.J.,andDm—
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Robertson, E. 0., and Peck, D. L., 1974, Thermal conductivity
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Robinson, G. D., McCallum, M. E., and Hayes, W. H., 1969,
Geologic map of the upper Holter Lake quadrangle, Lewis
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Roedder, Edwin, and Weiblen, P. W., 1975, Anomalous low-K
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Rohr, D. M., and Potter, A. W., 1963, Paleozoic rocks of the
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Rolsholt, J. N., Zartman, R. E., and Nkomo, I. T., 1973, Lead
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Rose, H. J., Jr., Christian, R. P., Dwornik, E. J., and
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Rose, P. R., 1972, Edwards Group, surface and subsurface,
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Ross, D. C., and Brabb, E. E., 1973, Petrography and struc-
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Rowan, L. C., and Wetlaufer, P. H., 1975, Iron-absorption-
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Rowan, L. C., Wetlaufer, P. H., Goetz, A. F. H., Billingsley,
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Runner, G. S., 1974, Flood on Buffalo Creek from Saunders
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Ryder, P. D., 1974, Ground water in the alluvium along the
Green River between its mouth and Woodbury, Ken-
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5 p.

1975, Ground water in the alluvium along the Cumber-
land River between Smithland, Kentucky, and Barkley
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Saboe, C. W., 1973, Flooded area map of Stillwater, Minne-
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Sawatzky, D. L., 1969, The meaning of “Laramide orogeny”
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Natl. Tech. Inf. Service, PB244974/AS, 137 p.

 

306

Schnabel, R. W., 1971, Surficial geologic map of the South-
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Soister, P. E., 1974, A preliminary report on a zone containing
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Survey open—file rept., 64 p.

 

GEOLOGICAL SURVEY RESEARCH 1975

Southwick, D. L., 1972, Vermilion granite-migmatite massif,
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Steele, T. D., and Dyar, T. R.,*1974, Harmonic analysis of
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’Steele, T. D., Gilroy, E. J., and Hawkinson, R. 0., 1974, An

assessment of areal and temporal variations in streamflow
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Stensrud, Howard, 1962, Lake Owens mafic complex, Medicine
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Stewart, D. B., Ross, Malcolm, Morgan, B. A., Appleman,
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Stewart, J. H., and Carlson, J. E., 1974a, Preliminary geologic
map of Nevada: U.S. Geol. Survey Misc. Field Studies
Map MF—609, 4 sheets.

1974b, Preliminary geologic map of Nevada: U.S. Geol.
Survey open-file rept., 2 color photos.

Strong, D. F., and Williams, H., 1972, Early Paleozoic flood
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Sun, R. J ., 1969, Theoretical size of hydraulically induced hori-
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1973, Hydraulic fracturing as a tool for disposal of

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Sun, R. J., and Mongan, C. E., 1974, Hydraulic fracturing in
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Swallow, L. A., and Fogarty, D. J., 1973, Flood of March
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Swallow, L. A., and Wood, G. K., 1973, Flood of March 1968
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Swanson, V. E., Huffman, Claude, Jr., and Hamilton, J. C.,
1974, Composition and trace-element content of coal, north-
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Program, Mineral Resources Work Group Rept., Feb.
1974: U.S. Dept. Interior open-file rept., p. 52—83.

 

 

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GEOLOGICAL SURVEY RESEARCH 1975

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COOPERATORS AND OTHER FINANCIAL CONTRIBUTORS
I DURING FISCAL YEAR 1975

[Cooperators listed are those with whom the U.S. Geological Survey had a written agreement for fiscal cooperation in fiscal year 1975. cosigned by
responsible officials of the Geological Survey and the cooperating agency. Agencies with whom the Geological Survey had research contracts and
to whom it supplied funds for such research are not listed. Parent agencies are listed separately from their subdivisions where separate
cooperative agreements for different projects were made with the parent agency and with a subdivision of the parent agency]

FEDERAL COOPERATORS Department of Defense—Continued

Defense Mapping Agency (IAGS)
Defense Nuclear Agency

Department of Agriculture:
U.S. Arms Control and Disarmament Agency

Agriculture Research Service
Forest Service

Soil Conservation Service
Statistical Reporting Service

Department of Health, Education, and Welfare, Public Health
Service

Department of the Air Force: Department of Housing and Urban Development

AFWL/PRP Kirtland AFB
Air Force Academy Department of the Interior:

Air Force Headquarters, Washington, DC. Alaska Power Administration
Air Force Systems Command Bonneville Power Administration

Air Force Weapons Laboratory (PRP) Bureau Of Indian Affairs

Alaskan Air Command Bureau of Land Management

Edwards Air Force Base Bureau of Mines

Eglin Air Force Base Bureau of Outdoor Recreation

Headquarters (AF-SC) Bureau of Reclamation

Headquarters (AFTAC/AC) Fish and Wildlife Service

Headquarters Pacific Air Forces National Park Service

mm 321% Combat firmer-t Group (SAC) Fomst Service

WWW“ OfficeoflmndUseandWaterPlanning

Office of Scientific Research Office of Salim Water

Rocket Propulsion laboratory Office of Water Resources Research

Vandenbmg Aja- Fume Base U.N. Geothermal Symposium
Water Resources Council

Department of the Army: "

Amy Electronics Command Dapamtment of Justice

Army Research Office

Cold Regions Research and Ehgineefing Ballot-atom Department of the Navy:

Construction Engineering March Laboratory Key West Naval Station

Corps of Engineers ‘ Wire Corps, Camp Pendleton

White Sands Missile Range Naval Air Development Center

Naval Facilities Engineering Command
Department of Com National Comic and Atmospheric Naval Weapons Center

Wham: Office of Naval Petroleum and Oil Shale Reel-we:
Buoy Oflh Office of Naval Resend:
mm Data Suwiee W Works Gunter» Gum
W 12de W
W lihvirmmrtal W Service unrtment of (State:
W” mm Am for Intentional W
WOUeanvaey WWWMWamOmum
W Weaiflaer Service [MW Joint Commission
W of Default: Department 11$sz
Advanced Research hofiects Agency Federal Highway Administration
Defense Intemgence Agency Office of the Secretary

309

310 GEOLOGICAL SURVEY RESEARCH 1975

Energy Research and Development Administration:
Albuquerque Operations Office
Division of Applied Technology
Division of Administrative Services
Division of Reactor Research and Development
Idaho Operations Office
Nevada Operations Office
Oak Ridge Operations Office
Office of the Director of Regulation
Richland Operations Office
Rocky Flats Division
San Francisco Operations Office
Savannah River Operations Office

Environmental Protection Agency:
Management Division
National Environmental Research Center
Office of Radiation Programs V
Office of Research and Development
Office of Solid Waste
Office of Water Programs .
Pacific Northwest Environmental Research Laboratory
Water and Hazardous Materials

Federal Energy Administration

General Services Administration

National Academy of Sciences

National Aeronautics and Space Administration
National Science Foundation

Nuclear Regulatory Commission

Office of Emergency Preparedness
Pacific Northwest River Basins Commission

Tennessee Valley Authority

Veterans Administration

STATE, COUNTY, AND LOCAL COOPERATORS

Alabama:
Alabama Forestry Commission
Alabama Highway Department
City of Mobile
County of Jefferson
Geological Survey of Alabama

Alaska:
Alaska Department of Aviation
Alaska Department of Fish and Game
Alaska Department of Highways
Alaska Department of Natural Resources
Alaska Geological Survey

Alaska—Continued

City and Borough of Juneau

City of Anchorage

City of Cordova

City of Kenai

City of Kodiak

City of Seward

Department of Environmental Conservation
Greater Anchorage Area Borough
Kenai Borough

North Star Borough

University of Alaska

Arizona:

Arizona Game and Fish Department

Arizona Highway Department

Arizona Water Commission

City of Flagstaff

City of Nogales

City of Safford

City of Tucson

City of Williams

Department of Health Services

Flood Control District of Maricopa County

Gila Valley Irrigation District

Lyman Water Company

Maricopa County Municipal Water Conservation District
No. 1

Office of the Governor

Pima County Board of Supervisors

Salt River Valley Water User’s Association

San Carlos Irrigation and Drainage District

Show Low Irrigation Company

University of Arizona

Arkansas :

Arkansas Department of Pollution Control and Ecology
Arkansas Division of Soil and Water Resources
Arkansas Geological Commission

Arkansas State Highway Commission

California :

Alameda County Flood Control and Water Conservation
District
Alameda County Water District
Antelope Valley-East Kern Water Agency
Berrenda Mesa Water District
Big Bear Lake Pest Abatement District
California Department of Conservation, Division of Mines
and Geology
California Department of Fish and Game
California Department of Water Resources
California Division of Highways, Materials and Research
Department
California Water Resources Control Board
Casitas Municipal Water District
Chino Basin Municipal Water District
City and County of San Francisco:
Hetch Hetchy Water Supply
Water Department

COOPERATORS AND OTHER FINANCIAL CONTRIBUTORS 311

California—Continued

City of Modesto, Public Works Department

City of Redding

City of San Diego

City of San Jose

City of San Rafael

City of Santa Barbara

City of Santa Cruz

Coachella Valley County Water District

Contra Costa County Flood Control and Water
Conservation District

County of Fresno

County of Madera

County of Modoc

County of Sacramento, Department of Public Works

County of San Diego, Board of Supervisors

County of San Mateo

Department of Transportation, Office of Structures

Desert Water Agency

East Bay Municipal Utility District

Fern Valley Water District

Georgetown Divide Public Utility District

Goleta County Water District

Hoopa Valley Tribe

Imperial County Department of Public Works

Imperial Irrigation District

Indian Wells Valley County Water District

Kern County

Kern County Water Agency

Lake County Flood Control and Water Conservation
District _

Livermore Amador Valley Water Management Agency

Los Angeles County, Department of County Engineers

Los Angeles County Flood Control District

Los Angeles Department of Water and Power

Madera Irrigation District

Marin Municipal Water District

Merced Irrigation District

Metropolitan Water District of Southern California

Mojave Water Agency

Montecito County Water District

Monterey County Flood Control and Water Conservation
District

Napa County Flood Control and Water Conservation
District

North Marin County Water District

Orange County Flood Cdntrol District

Orange County Water District

Oroville-Wyandotte Irrigation District

Pacheco Pass Water District

Paradise Irrigation District

Placer County Department of Public Works

Riverside County Flood Control and. Water Conservation
District

San Benito County Water Conservation and Flood Control
District

San Bernardino County Flood Control District

San Bernardino Valley Municipal Water District

San Luis Obispo County and Cities Area Planning
Coordinating Council

California—Continued

San Luis Obispo County Flood Control and Water
Conservation District
Santa Ana Watershed Planning Agency
Santa Barbara County Flood Control and Water
Conservation District
Santa Barbara County Water Agency
Santa Clara County Flood Control and Water District
Santa Cruz County Flood Control and Water Conservation
District
Santa Cruz County Planning Department
Santa Margarita and San Luis Rey Watershed Planning
Agencies
Santa Maria Valley Water Conservation District
Santa Ynez River Water Conservation District
Siskiyou County Flood Control and Water Conservation
District
Solano Irrigation District
Tehachapi-Cummings County Water District
Terra Bella Irrigation District
Tulare County Flood Control District
Turlock Irrigation District
United Water Conservation District
University of California:
Department of Engineering
School of Forestry and Conservation
Scripps Institute of Oceanography
Valley Community Services District
Valley Sanitary District
Ventura County Flood Control District, Riverside County
Western Municipal Water District
Waodbridge Irrigation District
Yolo County Flood Control and Water Conservation
District

Colorado :

Arkansas River Compact Administration
Cherokee Water District
City and County of Denver, Board of Water Commissioners
City of Aspen
City of Aurora, Department of Public Utilities
City of Colorado Springs, Department of Public Utilities
City of Fort Collins
City of Pueblo
Colorado City Water and Sanitation District
Colorado Department of Local Affairs
Colorado Department of Natural Resources:
Division of Water Resources
Division of Wildlife
Geological Survey
Colorado Department of Public Health, Water Pollution
Control Commission
Colorado River Water Conservation District
Colorado Water Conservation Board
Eagle County Commissioners
El Paso County Board of Commissioners
El Paso County Water Association
Huerfano County Conservation District
Jefferson County Health Department
Kiowa-Bijou Groundwater Management District

312

Colorado-Continued

Larimer County Planning Office

Lower South Platte Water Conservation District
Metro Denver Sewage Disposal District No. 1
Northern Colorado Water Conservation District
Pikes Peak Area Council of Governments

Pitkin County Board of County Commissioners
Rio Grande Water Conservation District

San Luis Valley Water Conservation District
Southeastern Colorado Water Conservancy District
Southern Ute_ Indian Tribe

Southwestern Water Conservation District
State of Colorado, Department of Highways
Teller County

Urban Drainage and Flood Control District

Connecticut:

City of Hartford, Department of Public Works

City of New Britain, Board of Water Commissioners
City of Torrington

Connecticut Geological and Natural History Survey
Department of Environmental Protection
Department of Transportation

State of Connecticut, Office of State Planning
Town of Fairfield

Delaware :

Delaware Geological Survey, University of Delaware
Department of Highways and Transporation, Division of
Highways

District of Columbia:

Department of Environmental Services

Florida:

Brevard County

Broward County

Broward County Air and Water Pollution Control Board
Central and Southern Florida Flood Control District
City of Boca Raton

City of Clearwater

City of Cocoa

City of Deerfield Beach

City of Fort Lauderdale

City of Fort Myers

City of Gainesville

City of Hallandale

City of Hollywood

City of Jacksonville

City of Juno Beach

City of Miami, Department of Water and Sewers
City of Pensacola

City of Perry

City of Pompano Beach

City of Riviera Beach

City of St. Petersburg

City of Sarasota

City of Tallahassee

City of Tampa

City of Temple Terrace

GEOLOGICAL SURVEY RESEARCH 1975

Florida—Continued

City of West Palm Beach
Collier County
Collier County Water Management District No. 1
Collier County Water Management District No. 7
Department of Pollution Control
Drvm' ‘ 'on of State Planm‘ng
East Central Florida Regional Planning Council
Englewood Water District
Escambia County
Florida Department of Natural Resources:
Bureau of Geology
Division of Parks and Recreation
Florida Department of Transportation
Game and Fresh Water Fish Commission
Hendry County
Hillsborough County
Jacksonville Area Planning Board
Jacksonville Recreation and Public Area
Lake County
Lake Worth Drainage District
Lee County
Loxahatchee River Environmental Control District
Manasota Basin Board
Manatee County, Board of County Commissioners
Marion County
Martin County
Metropolitan Dade County
Northwest Florida Water Management District
Orange County
Osceola County
Palm Beach County
Pinellas County
Reedy Creek Improvement District
Sarasota County
School of Marine and Atmospheric Science, University of
Miami Division of Planning
Seminole County
Southwest Water Management District
St. Johns River Water Management
Suwanee River Authority
Suwanee River Water Management District
Tampa Bay Regional Planning Commission
Tampa Port Authority
Village of Tequesta
Volusia County
Walton County

Georgia :

Chatham County

City of Brunswick

Dekalb County

Department of Natural Resources:
Earth and Water Division
Environmental Protection Division

Department of Transportation

Hawaii :

City and County of Honolulu
Honolulu Board of Water Supply

COOPERATORS AND OTHER FINANCIAL CONTRIBUTORS

Hawaii—Continued
State Department of Health
State Department of Land and Natural Resources
State Department of Transportation

Idaho:
City of Kellogg
Idaho Bureau of Mines and Geology
Idaho Department of Health and Welfare
Idaho Department of Highways
Idaho Department of Transportation
Idaho Department of Water Administration
Idaho State University
Idaho Water Resources Board
Southeast Idaho Council of Governments

Illinois:
Bloomington and Normal Sanitary District
City of Springfield
Cook County, Forest Preserve District
Du Page County
Environmental Protection Agency
Fountain Head Drainage District
Fulton County
Illinois Institute of Environmental Quality
Kane County
Lake County
McHenry County Regional Planning Commission
Sanitary District of Bloom Township
State Department of Registration and Education:
Illinois State Geological Survey
Illinois State Water Survey
State Department of Transportation:
Division of Highways
Division of Water Resources Management
The Metropolitan Sanitary District of Greater Chicago
University of Illinois at Urbana-Champaign

Indiana:
City of Indianapolis
Indiana Board of Health
Indiana Department of Natural Resources
Indiana Highway Commission
Town of Carmel

Iowa:
City of Cedar Rapids
City of Des Moines
City of Fort Dodge
Iowa Geological Survey
Iowa Natural Resources Council
Iowa State Highway Commission, Highway Research Board
Iowa State University
Iowa State University, Agricultural and Home Economics
Experiment Station
Linn County
University of Iowa, Institute of Hydraulic Research

Kansas:
City of Wichita
Kansas State Department of Health

Kansas—Continued
Kansas State Water Resources Board
Kansas-Oklahoma Arkansas River Commission
State Geological Survey of Kansas
State Highway Commission of Kansas

Kentucky:
Bureau of Highways, Department of Transportation
Department of Natural Resources
Kentucky Geological Survey, University of Kentucky
University of Kentucky Research Foundation

Louisiana:
Louisiana Department of Highways
Louisiana Department of Public Works
Louisiana Office of State Planning
Louisiana State University
Sabine River Authority of Louisiana
Sabine River Compact Administration

Maine:
Department of Environmental Protection
Maine Department of Economic Development
Maine Department of Transportation
Maine Geological Survey
Maine Public Utilities Commission

Maryland:

City of Baltimore, Water Division

Department of Natural Resources, Water Resources
Administration

Maryland Department of Health and Mental Hygiene

Maryland Department of Transportation, The State
Highway Administration

Maryland Geological Survey

Maryland National Capital Park and Planning Commission

Montgomery County

Washington Suburban Sanitary Commission

Massachusetts:
Department of Natural Resources, Division of Mineral
Resources
Department of Public Works:
Division of Highways
Division of Waterways
Metropolitan District Commission
State Water Resources Commission:
Division of Water Pollution Control
Division of Water Resources

Michigan:
Michigan Department of Agriculture, Soil and Water
Conservation Division
Michigan Department of Natural Resources:
Geological Survey Division
Water Resources Commission

Minnesota:
Metropolitan Council of the Twin Cities Area
Metropolitan Sewer Board of the Twin Cities Area
Minnesota Department of Highways

314

Minnesota—Continued

Minnesota Department of Natural Resources, Division of
Waters, Soils, and Minerals

Minnesota Pollution Control Agency

Minnesota State Planning Agency

Pelican River Watershed District

Mississippi :

City of Jackson

Harrison County Development Commission
Jackson County Board of Supervisors
Jackson County Port Authority

Mississippi Air and Water Pollution Control Commission
Mississippi Board of Water Commissioners
Mississippi Geological Survey

Mississippi Research and Development Center
Mississippi State Highway Department
Mississippi State University

Pat Harrison Waterway District

Pearl River Basin Development District

Pearl River Valley Water Supply District
Yellow Creek Port Authority

Missouri :

Curators of the University of Missouri
Department of Natural Resources:
Division of Environmental Quality, Clean Water
Commission
Research Technical Information
Metropolitan St. Louis Sewer District
Missouri Department of Business and Administration,
Division of Geological Survey and Water Resources
Missouri State Highway Commission
Missouri Water Pollution Board
St. Louis County

Montana:

Endowment and Research Foundation—~Montana State
University

Lewis and Clark County, Board of County Commissioners

Montana Bureau of Mines and Geology

Montana Department of Health and Environmental Sciences

Montana Department of Intergovernmental Relations

Montana Department of Natural Resources

Montana State Fish and Game Department

Montana State Highway Commission

Old West Regional Commission

Nebraska :

Clay County Ground Water Conservation District
Filmore County Ground Water Conservation District
Hamilton County Ground Water Conservation District
Kansas-Nebraska Big Blue River Compact Administration
Lower Loup Natural Resources District

Lower Platte South Natural Resources District
Nebraska Department of Environmental Control
Nebraska Department of Water Resources

Nebraska Game and Parks Commission

Nebraska Natural Resources Commission

Seward County Ground Water Conservation District
State Department of Roads

GEOLOGICAL SURVEY RESEARCH 1975

Nebraska—Continued

University of Nebraska, Conservation and Survey Division
Upper Big Blue Natural Resources District
York County Ground Water Conservation District

Nevada :

Nevada Bureau of Mines and Geology
Nevada Department of Conservation and Natural Resources
Nevada State Highway Department

New Hampshire:

New Hampshire Department of Resources and Economic
Development

New Hampshire Water Resources Board

New Hampshire Water Supply and Pollution Control
Commission

New Jersey:

Bergen County

Camden County Board of Freeholders

Delaware River Basin Commission

New Jersey Department of Agriculture, State Soil
Conservation Committee

New Jersey Department of Environmental Protection

New Jersey Department of Transportation

North Jersey District Water Supply Commission

Passaic Valley Water Commission

Rutgers State University

Township of Cranford

New Mexico:

Albuquerque Metropolitan Arroyo Flood Control Authority
City of Las Cruces

Costilla Creek Compact Commission

Elephant Butte Irrigation District

Interstate Stream Commission

New Mexico Bureau of Mines and Mineral Resources
New Mexico State Engineer

New Mexico State Highway Department

Pecos River Commission

Rio Grande Compact Commission

University of New Mexico

New York:

Board of Hudson River—Black River Regulating District
Central New York State Parks Commission
City of Albany
City of Auburn
City of New York:
Board of Water Supply
Environmental Protection Agency
County of Chautauqua
County of Cortland
County of Dutchess:
Board of Supervisors
Department of Public Works
County of Nassau, Department of Public Works
County of Onondaga:
Department of Public Works
Water Authority
County of Orange

COOPERATORS AND OTHER FINANCIAL CONTRIBUTORS I 315

New York—Continued

County of Putnam
County of Rockland Drainage Agency
County of Suffolk:
Department of Environmental Control
Water Authority
County of Ulster, Ulster County Legislature
County of Westchester, Department of Public Works
County of Wyoming
Department of Environmental Conservation:
Environmental Management
Environmental Quality
Environmental Research
Facilities and Construction Management
Department of Transportation
Monroe County Water Authority
New York State College of Agriculture and Life Sciences
New York State Department of Health
New York State Education Department, Museum and
Science Service
Oswegatchie-Cranberry Reservoir Commission
Power Authority of the State of New York
State University of New York, College of Environmental
Science and Forestry
Town of Brighton
Town of Clarkstown
Town of Middlebury
Town of Warwick
Village of Nyack

North Carolina:

City of Asheville, Public Works Department

City of Burlington

City of Charlotte

City of Durham, Department of Water Resources

City of Greensboro

City of Winston-Salem

North Carolina Department of Conservation and
Development, Division of Mineral Resources

North Carolina Department of Natural and Economic
Resources, Office of Earth Resources

North Carolina Department of Water and Air Resources

State Department of Transportation

Triangle “J” Council of Governments

Water Research Institute

Wilson County

North Dakota:

North Dakota Geological Survey

Oliver County, Board of County Commissioners
State Highway Department

State Water Commission

Ohio :

City of Canton

City of Columbus, Department of Public Service

Miami Conservancy District

Ohio Department of Natural Resources

Ohio Department of Transportation

Ohio Department of Transportation, Division of Highways
Ohio Environmental Protection Agency

Ohio—Continued

Three Rivers Watershed District

Oklahoma:

City of Oklahoma City, Water Department

Oklahoma Department of Highways

Oklahoma Geological Survey

Oklahoma Soil Conservation Board

Oklahoma Water Resources Board

State Department of Health, Environmental Health Service

Oregon:

Burnt River Irrigation District

City of Astoria

City of Corvallis

City of Eugene, Water and Electric Board

City of McMinnville, Water and Light Department
City of Portland, Bureau of Water Works

City of The Dalles

Confederated Tribes of the Umatilla Indian Reservation
Confederated Tribes of the Warm Springs Reservation
Coos Bay-North Bend Water Board

Coos County, Board of Commissioners

Cowlitz County

Douglas County

Lakeside Water District

Lane County, Department of General Administration
Oregon State Board of Higher Education

Oregon State Game Commission

Oregon State Highway Commission

Oregon State Water Resources Department

Pennsylvania :

Chester County Commissioners
Chester County Health Department
Chester County Water Resources Authority
City of Bethlehem
City of Easton
City of Harrisburg
City of Philadelphia, Water Department
Department of Environmental Management
Pennsylvania Department of Environmental Resources:
Bureau of, Topographic and Geologic Survey
Bureau of Water Quality Management
Office of Engineering and Construction
State Soil and Water Conservation Commission
Pennsylvania Department of Transportation
Pennsylvania Office of State Planning and Development
Susquehanna River Basin Commission

Rhode Island:

City of Providence, Department of Public Works
State Department of Natural Resources:
Division of Fish and Wildlife
Division of Planning and Development
State Department of Transportation, Division of Roads and
Bridges
State Water Resources Board

South Carolina:

Commissioners of Public Works, Spartanburg Water Works

316

South Carolina—Continued

South Carolina State Development Board

State Development Board, Division of Geology
State Highway Department

State Land Resources Conservation Commission
State Pollution Control Authority

State Public Service Authority

State Water Resources Commission

South Dakota:

Black Hills Conservancy Subdistrict

City of Sioux Falls

City of Watertown

East Dakota Conservancy Subdistrict

South Dakota Department of Natural Resource
Development

South Dakota Department of Transportation and State
Geological Survey

Tennessee:

Chickasaw Basin Authority

City of Chattanooga

City of Franklin

City of Lawrenceburg

City of Manchester

»City of Memphis, Board of Light, Gas, and Water
Commissioners

Lincoln County

Metropolitan Government of Nashville and Davidson
County

Murfreesboro Water and Sewer Department

Tennessee Department of Conservation:

Division of Geology
Division of Water Resources

Tennessee Department of Highways

Tennessee Department of Public Health, Division of Water
Quality Control

Tennessee Department of Transportation

Tennessee Game and Fish Commission

Tennessee State Planning Office

University of Tennessee

Texas:

City of Austin

City of Dallas, Public Works Department
City of Fort Worth

City of Houston

County of Dallas

Sabine River Compact Administration
Texas Highway Department

Texas Water Development Board

Utah:

Bear River Commission

Salt Lake County

State Department of Highways

State Department of Natural Resources, Division of Water
Rights

Utah Geological and Mineralogical Survey

Utah Legislative Council

GEOLOGICAL SURVEY RESEARCH 1975

Vermont :

State Department of Highways

State Department of Water Resources, Planning and
Development Division

Vermont Geological Survey

Virginia:

City of Alexandria
City of Newport News, Department of Public Utilities
City of Norfolk:
Department of Utilities
Division of Water Supply
City of Roanoke
City of Staunton
County of Chesterfield
County of Fairfax
Virginia Department of Conservation and Economic
Development, Division of Mineral Resources
Virginia Department of Highways
Virginia Polytechnic Institute and State University
Virginia State Water Control Board

Washington:

Chehalis Tribal Council
City of Port Angeles
City of Seattle, Department of Lighting
City of Tacoma:
Department of Public Utilities
Department of Public Works
Clark County Public Utility District
Coleville Business Council
Cowlitz County Public Utility District
Municipality of Metropolitan Seattle
Pacific County
Quinault Business Committee
Squaxin Indian Tribe
Swinomish Tribal Council
The Evergreen State College
Tulalip Tribal Council
University of Washington
Washington State Department of Ecology
Washington State Department of Fisheries
Washington State Department of Game
Washington State Department of Highways
Washington State Department of Natural Resources,
Division of Mines and Geology
Yakima Tribal Council

West Virginia:

Clarksburg Water Board

Morgantown Water Commission

West Virginia Department of Highways

West Virginia Department of Natural Resources, Division of
Water Resources

West Virginia Geological and Economic Survey

Wisconsin :

City of Madison
City of Middleton
Dane County

COOPERATORS AND OTHER FINANCIAL CONTRIBUTORS

Wisconsin—Continued
Douglas County
Madison Metropolitan Sewerage District
Southeastern Wisconsin Regional Planning Commission
State Department of Natural Resources
State Department of Transportation, Division of Highways
The University of Wisconsin-Extension, Geological and
Natural History Survey
Town of Kronenwetter
Wyoming:
City of Cheyenne, Board of Public Utilities
State Highway Commission of Wyoming
Wyoming Department i 1‘ Economic Planning and
Development
Wyoming Game and Fish Commission
Wyoming State Agriculture Commission
Wyoming State Department of Environmental Quality
Wyoming State Engineer

OTHER COOPERATORS AND CONTRIBUTORS

Appalachian Regional Commission
Coastal Plains Regional Commission
Government of Algeria
Government of American Samoa
Government of Brazil

Government of Burma

Government of Colombia

Government of Guam

317

Government of Iran
Government of Jordan
Government of Nepal
Government of Nicaragua
Government of Oman
Government of Peru
Government of the Philippines
Government of Saudi Arabia
Government of Thailand
Government of Turkey
Government of Yemen
Northern Grant Plains Resources Programs
Ozarks Regional Commission
Permittees and licensees of the Federal Bower Commission
Puerto Rico:
Gobierno Municipal De Bayamon
Puerto Rico Department of Natural Resources

i’uerto Rico Environmental Quality Board
Puerto Rico Water Resources Authority

Trust Territory of the Pacific Islands
United Nations

Virgin Islands, Department of Public Works

U.S. GEOLOGICAL SURVEY OFFICES

Official and (or) office

Director .......................
Associate Director ...............
Senior Scientist .................

Assistant Director, Research .......
Assistant Director, Programs .......

Assistant Director, Environmental
Conservation.
Assistant Director, Administration . . .
Assistant Director ...............
Chief, Office of Land Information and
Analysis.
Earth Resources Observation
Systems Program.
Earth Sciences Applications
Program.
Environmental Impact Analysis . . .
Geography Program ............
Resources and Land Information
Program.
Chief, Administrative Division ......
Chief, Computer Center Division
Chief, Conservation Division .......
Chief, Geologic Division ...........
Chief, Publications Division ........
Chief, Topographic Division ........
Chief, Water Resources Division .....

Official and (or) office

Assistant Director, Eastern Region . . .
Assistant Director, Central Region . . .

Assistant Director, Western Region

318

HEADQUARTERS OFFICES

Name and telephone number

V. E. McKelvey (703 860-7411)
W. A. Radlinski (703 860-7411)
Frank E. Clarke (202 343-3888)

James R. Balsley (703 860-7488) . . . .

Dale D. Bajema (acting) (703
860-7435).

Henry W. Coulter (703 860-7491)

Edmund J. Grant (703 860-7201)

Montis R. Klepper (703 860-7481)

James R. Balsley (acting) (703
860-7488). ‘

John M. DeNoyer (703 860-7881) . . .

Donald R. Nichols (703 860-7547)

Daniel B. Krinsley (703 860-7455)
James R. Anderson (703 860-6344) .
J. Ronald Jones (703 860-7435)

Edmund J. Grant (703 860-7201)
Carl E. Diesen (703 860-7106) ......
Russell G. Wayland (703 860-7524) . .
Richard P. Sheldon (703 860—6531) . .
Harry D. Wilson, Jr. (703 860-7181‘)
Robert H. Lyddan (703 860-6231)
Joseph S . Cragwall, Jr. (703
860-6921).

PRINCIPAL FIELD OFFICES

Name and telephone number

William B. Overstreet (703 860-7414) .
Thad G. McLaughlin (303 234-4630) .

Joel M. Johanson (415 323-2711)

Address

101 National Center.

102 National Center.

Rm. 4441, Interior Bldg.,Washington,
DC. 20240.

104 National Center.

105 National Center.

106 National Center.

201 National Center.
171 National Center.
104 National Center.

1925 Newton Sq. East, Reston, Va.,
22090.
104 National Center.

760 National Center.
115 National Center.
105 National Center.

201 National Center.
801 National Center.
600 National Center.
911 National Center.
341 National Center.
516 National Center.
409 National Center.

Address

109 National Center.

Bldg. 25, Federal Center, Denver,
Colo. 80225.

345 Middlefield Rd., Menlo Park,
Calif. 94025.

 

U.S. GEOLOGICAL SURVEY OFFICES

319

SELECTED FIELD OFFICES IN THE UNITED STATES AND PUERTO RICO

[Temporary offices are not included; list is current as of July 1. 1975. Correspondence to
the following offices should be addressed to the Post Office Box. if one is given]

Location

Arizona, Flagstaff 86001 ..........
California, Menlo Park 94025 ......
Colorado, Denver 80225 ..........
Missouri, Rolla 65401 ............
South Dakota, Sioux Falls 57198

Location

Central Region:
Denver, CO 80225 .............

Eastern Region:
Washington, DC 20006 .........

Gulf of Mexico Outer Continental
Shelf Operations:
Metairie, LA 70011 ..........

Western Region:
Menlo Park, CA 94025 ..........

Location

Alaska, Anchorage 99510 .........

Arizona, Phoenix 85003 ..........
California, Los Angeles 90012 ......

Bakersfield 93301 .............

Menlo Park 94025 .............

Sacramento 9 58 25 .............

Santa Barbara 93102 ...........

COMPUTER CENTER DIVISION

Official in charge and telephone number

James E. Crawforth (602 774-1312)
James L. Mueller (415 323-2661) .
Frederick B. Sower (303 234-5277) . .
Glenn A. Ridgeway (314 364-6985)
Ralph J. Thompson (605 594-6555)

CONSERVATION DIVISION

REGIONAL OFFICES

Official in charge and telephone number

George H. Horn, Regional
Conservation Manager (303
234-2855).

George F. Brown, Regional
Conservation Manager (202
343-4685).

A. Dewey Acuff, Conservation
Manager (504 680-9381);

Willard C. Gere, Regional Conservation
Manager (415 323-2108).

AREA AND DISTRICT OFFICES
Official in charge and telephone number

Rodney A. Smith, Alexander A.
Wanek (907 278-3571).

Vacant (602 261-3766) ...........

Fred J. Schambeck, Keith A. Yenne
(213 688-2846).

Donald F. Russell (805 861-4186) . . .

Leo H. Saarela (415 323-2108).
Henry L. Cullins, Jr. (415
323-2563).
Reid T. Stone (415 323-2841).
Robert D. Morgan, (acting) (916
484-4219).
Michael F. Reitz (805 963-3305) . . . .

Address

601 East Cedar Ave.

345 Middlefield Rd.

Rm. E2608, Bldg. 53, Federal Center.
PO. Box 41.

EROS Data Center.

Address

Bldg. 25, Federal Center; Villa Italia,
Wadsworth and Alameda.

Suite 316, 1825 K St., NW.

P.O. Box 7944; 336 Imperial Office
Bldg, 3301 North Causeway Blvd.

345 Middlefield Rd.; 701 Laurel St.

Address

PO. Box 259; 212 Skyline Bldg, 218
E St.

Rm. 208, 522 North Central Ave.

Rm. 7744, Federal Bldg., 300 North
Los Angeles St.

Rm. 309, Federal Bldg., 800 Truxtun
Ave.

345 Middlefield Rd.; 701 Laurel St.

Rm. W-2231, Federal Bldg., 2800
Cottage Way.

Rm. 214, Post Office Bldg, 836
Anacapa St.

320

Location

Colorado, Denver 80225 ..........

Durango 81301 ...............
Grand Junction 81501 ..........

Idaho, Pocatello 83201 ...........
Louisiana, Houma 70360 ..........
Lafayette 70501 ..............

Lake Charles 70601 ............
Metairie 70011 ................

Mississippi, Jackson 39201 .........

Missouri, Rolla 65401 ............
Montana, Billings 59103 ..........

New Mexico, Artesia 88210 ........
Carlsbad 88220 ...............

Farmington 87401 .............
Hobbs 88240 .................
Roswell 88201 ................
Oklahoma, McAlester 7 4501 .......

Oklahoma City 73118 ..........
Tulsa 74135 ..................

Oregon, Portland 97208 ...........
Texas, Freeport 77541 ............
Utah, Salt Lake City 84138 ........

Washington, D.C. 20006 ..........

Wyoming, Casper 82601 ..........

Newcastle 8 27 0 1 ..............

Rock Springs 82901 ............

Thermopolis 82443 ............

GEOLOGICAL SURVEY RESEARCH 1975

Official in charge and telephone number

James A. Carter, (acting) (303
234-3984, 4484).
John P. Storrs (303 837-4751).
Sterling R. Osborne (303
234-5042).

Daniel A. Jobin (303 234-4435).
Jerry W. Long (303 247-5144) ......
Peter A. Rutledge, James W. Hager

(303 242-3281).
John T. Skinner (208 235-6262)

John Borne (504 868-4033) ........
Elmo G. Hubble, (318 232-6037) .
Robert Darrow (318 478-6440) .....
Harry McAndrews (504 680-9341).
Donald W. Solanas (504 680-9333).
Jake B. Lowenhaupt (504
680-9251). ~
Charles B. Mullins (504 680-9301).
Thomas E. Godfrey (601 969-4405) . .

C. V. Collins (314 364-8411) .......
Albert F. Czarnowsky '(406
245-6181).
Jim S. Hinds (406 245-6185).
Virgil L. Pauli (406 245-6368).
James A. Knauff (505 746-4841) . . . .
Robert S. Fulton (505 885-6454)

J. E. Fassett, Philip T. McGrath (505
325-4572).

Arthur R. Brown (505 393-3612)

N. 0. Frederick, Donald M. VanSickle
(505 622-9257).

Alexander M. Dinsmore (918
423-5030).

Charley W. Nease (405 231-4806) .

Edward L. Johnson, Floyd L. Stelzer
(918 581-7631).

Jesse L. Colbert (503 234-4796)

Vacant (713 233-2604) ...........

Donald C. Alvord (801 524-5643).
Edgar Guynn (801 524-5650).
Jackson W. Moffitt (801 524-5646).

William B. Gazdik, Harry A. Dupont,

John A. Lees (acting) (202
343-4685).

Charles J. Curtis (307 265-3407).
Edward Haymaker (307 265-3247).
Elmer M. Schell (307 265-3421).

Glenn E. Worden (307 746-2737)

John A. Fraher (307 362-6422).
Arne A. Mattila (307 362-7350).

George Kinsel (307 864-3477) ......

Address

Bldg. 25, Federal Center.

P.0. Box 1809; 125 West 10th St.

PO. Box 2939; Federal Bldg, 4th St.
and Rood Ave.

PO. Box 1610; Federal Bldg., 150
South Arthur St.

P.O. Box 1269.

PO. Box 52289; 239 Bendel Rd.

P.O. Box 6088, Drew Station.

P.O. Box 7944; 336 Imperial Office
Bldg, 3301 North Causeway Blvd.

PO. Box 7966.

505 Unifirst Federal Savings & Loan
Bldg.

PO. Box 936; Suite 101, 400 Main St.

PO. Box 2550; 217 Post Office Bldg.

Drawer U; 105 South 4th St.

P.O. Box 1716; Federal Bldg, 114
South Halagueno St.

PO. Box 959; Petroleum Club Plaza,
3535 East 30th St.

P.O. Box 1157; 205 North Linam St.

Drawer 1857; Federal Bldg. and U.S.
Courthouse, Richardson Ave. at 5th
St.

P.O. Box 816; 509 South 3d St.

Suite 404, 50 Penn Pl.
6136 East 32nd Pl.

PO. Box 3202, 830 NE. Holladay St.

P.O. Box 2006.

Rm. 8422, 8426, and 8432, Federal
Bldg, 125 South State St.

Suite 316, 1825 K St., N.W.

P.O. Box 2859 and 2373; Rm. 2002
and 2001, Federal Bldg. and Post
Office, 100 East B St.

PO. Box 219; Suite 201, 100% West
Main St.

PO. Box 1170; Rm. 201 and 204,
First Security Bank Bldg, 502
South Front St.

P.O. Box 590; Rm. 202, Federal Bldg.

U.S. GEOLOGICAL SURVEY OFFICES

321

EARTI-I RESOURCES OBSERVATION SYSTEMS PROGRAM

Location

Mississippi, Bay St. Louis 39521

South Dakota, Sioux Falls 57198

Location

Central Region:
Denver, CO 80225 .............

Eastern Region:
Reston, VA 22092 .............

Western Region:
Menlo Park, CA 94025 ..........

Location

Alaska, Anchorage 99501 .........
College 99701 ................
Arizona, Flagstaff 86001 ..........

Arkansas, Little Rock 72204 .......
California, La Jolla 92037 .........

San Francisco 94105 ...........
Connecticut, Middletown 06457 .
Florida, Miami 33139 ............
Hawaii, Hawaii National Park 96718 . .
Kentucky, Lexington 40503 .......
Massachusetts, Boston 02110 .......

Woods Hole 02543 .............
New Mexico, Albuquerque 87115

Ohio, Columbus 43210 ...........
Pennsylvania, Carnegie 1 5106 ......
Puerto Rico, San Juan 00936 .......
Tennessee, Knoxville 37902 ........
Texas, Corpus Christi 78411 .......
Utah, Salt Lake City 84111 ........
Washington, Seattle 98105 .........

Spokane 99201 ...............

Wyoming, Laramie 82070 ....... -. .

Official in charge and telephone number

Gary W. North (601 688-3541) .....

Allen H. Watkins (605 594-6123)

GEOLOGIC DIVISION

REGIONAL OFFICES
Official in charge and telephone number

Ralph L. Erickson, Regional Geologist
(303 234-3624),

Eugene H. Roseboom, Jr., Regional
Geologist (703 860-6631).

David L. Jones, Regional Geologist
(415 323-2214).

OFFICES
Official in charge and telephone number

Donald H. Richter (907 344-2663)

Florence R. Weber (907 479-7 245)

Michael H. Carr (602 774-5261, ext.
1455)

Boyd R. Haley (501 371-1616) .....

George W. Moore (714 453-2820)

Ralph B. Matthiesen (415 556-7725) .
Fred Pessl, Jr. (203 346-5542) ......
E. A. Shinn (305 350-4239) ........
Robert I. Tilling (808 967-7485) . . . .
Wilds W. Olive (606 252-2552) .....
M. H. Pease, Jr. (617 223-7202) .....
John C. Behrendt (617 548-8700)

Jon R. Peterson (505 264-4637)

James M. Schopf (614 421-2393)

Reginald P. Briggs (412 644—2920) . . .
John M. Aaron (809 766-5340) .....
Robert A. Laurence (615 524-4268).
Louis E. Garrison (512 888-3241) . . .
Lowell S. Hilpert (801 524-5640)

Thane H. McCulloh (206 543-5059) . .
Albert E. Weissenborn (509

456-4677).
J. David Love (307 745-4495) ......

Address

Bldg. 1 1 00, National Space
Technology Laboratories.
EROS Data Center.

Address

Bldg. 25, Federal Center.

953 National Center, 12201 Sunrise
Valley Dr.

345 Middlefield Rd.

A dd ress

216 Skyline Bldg., 218 E St.
P.O. Box 80586.
601 East Cedar Ave.

3815 West Roosevelt Rd.

PO. Box 271; 8604 La Jolla Shores
Dr.

Rm. 7067, 390 Main St.

P.O. Box 470.

Fisher Island Station.

Hawaiian Volcano Observatory,

2035 Regency Rd.

80 Broad St.
U.S. Geological Survey, Woods Hole.
Albuquerque Seismological Center,
Kirtland AFB, East Bldg. 10002.
Orton Hall, Ohio State Univ., 155
South Oval Dr.

PO. Box 420.

GPO Drawer 2230.

301 West Cumberland Ave.

P.O. Box 6732; Univ. of Corpus
Christi.

Rm. 8416, Federal Bldg, 125 South
State St.

Dept. of Oceanography, WB 10, Univ.
of Washington.

West 920 Riverside Ave.

Box 3007, Univ. Station, Geology
Hall, Univ. of Wyoming.

322

GEOLOGICAL SURVEY RESEARCH 1975

PUBLICATIONS DIVISION

PUBLIC INQUIRIES OFFICES

[Each of the following offices provides over-the-counter sales service for Survey book reports and geologic
and topographic maps relating to its geographic area. and for selected Survey reports of general interest]

Location

Alaska, Anchorage 99501 .........
California, Los Angeles 90012 ......

San Francisco 94111 ...........
Colorado, Denver 80202 ..........
District of Columbia, Washington

20244.
Texas, Dallas 75202 ..............
Utah, Salt Lake City 84138 ........
Virginia, Reston 22092 ...........

Washington, Spokane 99201 .......

Official in charge and telephone number

Margaret I. Erwin (907 2770577) . . .
Lucy E. Birdsall (213 688-2850)

Jean V. Molleskog (415 556-5627)
Sylvia T. Huhta (303 837-4169)

Bruce A. Hubbard (202 343-8073)
Mildred V. Smith (214 749-3230)
Wendy R. Hassibe (801 524-5652) . . .
A. Ernestine Jones (703 860-6167)
Eula M. Thune, (acting) (509

456-2524).

DISTRIBUTION CENTERS

Address

Rm. 108, Skyline Bldg., 508 2d Ave.

Rm. 7638, Federal Bldg, 300 North
Los Angeles St.

Rm. 504, Custom House, 555 Battery
St.

Rm. 1012, Federal Bldg, 1961 Stout
St.

Rm. 1028, General Services Bldg.,
19th and F Sts., NW.

Rm. 1045, Federal Bldg., 1100
Commerce St.

Rm. 8102, Federal Bldg, 125 South
State St. -

Rm. 1C402, National Center, 12201
Sunrise Valley Dr.

Rm. 678, US. Court House, West 920
Riverside Ave.

[Survey maps are distributed by mail and over-the-counter from the following centers]

Location

Virginia, Arlington 22202 1‘ 2 ......
Colorado, Denver 802253 .........
Alaska, Fairbanks 997014 .........

Location

California, Menlo Park 94025 ......
Colorado, Denver 80225 ..........
Missouri, Rolla 65401 ............
South Dakota, Sioux Falls 57198
Virginia, Reston 22090 ...........
Reston 22092 ................

Official in charge and telephone number

John J. Curry (703 557-2751) ......

Dwight F. Canfield (303 234-3832) . .

Natalie A. Cornforth, (907 452-1951,
ext. 174).

TOPOGRAPHIC DIVISION

Official in charge and telephone number

Roy R. Mullen (415 323-2411) .....
Albert E. Letey (303 234-2351)

A. Carroll McCutchen (314 364-3680).
Allen H. Watkins (605 594-6123)

Roy E. Fordham (703 471-1711)
Peter F. Bermel (703 860-6352)

1 For maps of areas east of the Mississippi River (including Minnesota).
2 Also, provides mail and over-the-counter distribution for Survey book reports.
3For maps of areas west of the Mississippi River (including Louisiana).

4For residents of Alaska.

Address

1200 South Eads St.
Box 25286, Federal Center.
310 First Ave.

Address

345 Middlefield Rd.

Bldg. 25, Federal Center.

PO. Box 133; 9th and Pine Sts.
EROS Data Center.

1925 Newton Sq. East.

567 National Center.

Location

Northeastern Region:
Reston, VA 22092 .............

Southeastern Region: ' ‘
Atlanta, GA 30309 ............

Central Region:
Denver, CO 80225 .............

Western Region:
Menlo Park, CA 94025 ..........

Location

Alabama, Tuscaloosa 35486 ........
Alaska, Anchorage 99501 .........
Arizona, Tucson 85701 ...........
AArkansas, Little Rock 72201 .......
California, Menlo Park 94025 ......

Colorado, Denver 80225 ..........
Connecticut, Hartford 06101 .......

Delaware ......................
District of Columbia .............
Florida, Tallahassee 32303 .........
Georgia, Doraville 30340 ..........
Hawaii, Honolulu 96815 ..........
Idaho, Boise 83724 . . . . , .........

Illinois, Champaign 61820 .........
Indiana, Indianapolis 46202 ........
Iowa, Iowa City 52240 ...........
Kansas, Lawrence 66045 ..........
Kentucky, Louisville 40202 ........
Louisiana, Baton Rouge 70806 .....

Maine ........................
Maryland, Parkville . 21 234 .........

U.S. GEOLOGICAL SURVEY OFFICES

WATER RESOURCES DIVISION

REGIONAL OFFICES

Officialln charge and telephone number

Joseph T. Callahan, Regional
Hydrologist (703 860-6985).

Leslie B. Laird, Regional Hydrologist
(404 526-5395).

Alfred Clebsch, Jr., Regional
Hydrologist (303 234-3661).

William H. Robinson (acting), Regional
Hydrologist (415 323-8111).

DISTRICT OFFICES

Official in charge and telephone number

William J. Powell (205 752-8104)

Harry Hulsing (907 277-5526, 5527) .
Horace M. Babcock (602 792-6671).
Richard T. Sniegocki (501 378-5246).

Lee R. Peterson (415 323-8111, ext.
2326, 2327, 2465, 2466).

James E. Biesecker (303 234-5092) . .

Frederick H. Ruggles, Jr. (203
244-2528).

Walter F. White, Jr. (301 661-4664)

............ do

Clyde S. Conover (904 386-1118) . . .

John R. George (404 455-1211)

Frank T. Hidaka (808 955-0251) .

Hal K. Hall (208 342-2711, ext.
2537).

Lawrence A. Martens (217 359-3918).
James L. Cook (317 269-7101) .....
Sulo W. Wiitala (319 338-5521) .....

Joseph S. Rosenshein (913 864-4321).

Robert V. Cushman (502 582-5241).

Albert N. Cameron (504 387—0181,
ext. 281).

John A. Baker (617 223-2822) .....
Walter F. White, Jr. (301 661-4664) . .

323

Address

433 National Center, 12201 Sunrise
Valley Dr.

Suite 200, 1459 Peachtree St. NE.

Bldg. 25, Federal Center.

345 Middlefield Rd.

Address

PO. Box V; Rm. 202, Oil and Gas
Board Bldg., Univ. of Alabama.

Skyline Bldg., 218 E St.

Federal Bldg., 301 W. Congress.

Rm. 2301, Federal Office Bldg., 700
West Capitol Ave.

855 Oak Grove Ave.

Bldg. 53, Federal Center.

P.0. Box 715; Rm. 235, Post Office
Bldg., 135 High St.

See Maryland District Office.

Do.

Suite F-240, 325 John Knox Rd.

Suite B, 6481 Peachtree Industrial
Blvd.

1833 Kalakaua Ave.

PO. Box 036; Rm. 365, Federal Bldg.
and US. Courthouse, 550 West
Fort St.

P.O. Box 1026; 605 North Neil St.

1819 North Meridian St.

P.O. Box 1230; Rm. 269, Federal
Bldg.

1950 Avenue “A”—Campus West,
Univ. of Kansas.

Rm. 572, Federal Bldg., 600 Federal
Pl.

P.O. Box 66492; 6554 Florida Blvd.

See Massachusetts District Office.
8809 Satyr Hill Rd.

324

Location

Massachusetts, Boston 02114 .......
Michigan, Okemos 48864 ..........

Minnesota, St. Paul 55101 .........
Mississippi, Jackson 39206 .........
Missouri, Rolla 65401 ............
Montana, Helena 59601 ...........
Nebraska, Lincoln 68508 ..........
Nevada, Carson City 89701 ........

New Hampshire .................
New Jersey, Trenton 08607 ........

New Mexico, Albuquerque 87106
New York, Albany 12201 . . .I ......
North Carolina, Raleigh 27602 .....
North Dakota, Bismarck 58501 .....
Ohio, Columbus 43212 ...........
Oklahoma, Oklahoma City 73102 . . .
Oregon, Portland 97208 ...........
Pennsylvania, Harrisburg 17108 .....
Puerto Rico, San Juan 00934 .......
Rhode Island ...................
South Carolina, Columbia 29201 . . . .
South Dakota, Huron 57350 .......
Tennessee, Nashville 37203 ........
Texas, Austin 78701 .............
Utah, Salt Lake City 84138 ........
Vermont ......................
Virginia, Richmond 23220 .........
Washington, Tacoma 98402 ........
West Virginia, Charleston 25301

Wisconsin, Madison 53706 .........
Wyoming, Cheyenne 82001 ........

Location

Brazil, Rio de Janeiro .............

GEOLOGICAL SURVEY RESEARCH 1975

Official in charge and telephone number

John A. Baker (617 223-2822) .....

T. Ray Cummings (517 372-1910, ext.
561).

Charles R. Collier (612 725-7841,
7842).

Lamar E. Carroon (601 969-4600) . . .

Anthony Homyk, Jr. (314 364—1599) .

George M. Pike (406 442-9040, ext.
3263).

Kenneth A. MacKichan (402
471-5082).

John P. Monis (702 882-1388) ......

John A. Baker (617 223-2822) .....

Harold Meisler (609 599-3511, ext.
212).

William E. Hale (505 766—2246) .....

Robert J. Dingman (518 472-3107) . .
Ralph 0. Heath (919 755-4510) .....

Walter R. Scott (701 255-4011, ext.
227, 228).

James F. Blakey (614 469-5553) .

James H. Irwin (405 231-4256) .....

Stanley F. Kapustka (503 234-3361,
ext. 4776, 4777, 4778).

Norman H. Beamer (717 782-3468) . .

Ernest D. Cobb (809 783-4660)

John A. Baker (617 223-2822) .. . ..

John S. Stallings (803 765-5966) . . . .

John E. Powell (605 352-8651, ext.
293, 294).

Stanley P. Sauer (615 749-5424)

1. Dale Yost (512 397-5766) ....... .
Theodore Arnow (801 524-5663)

John A. Baker (617 223-2822) .....

William E. Forrest (804 782-2427)

John F. McCall (206 593-6510) .....

Edwin E. Harris (304 343-6181, ext.
310, 311, 339).

Charles L. R. Holt (608 262-2488).

Samuel W. West (307 778-2220, ext.
2111)

OFFICES IN OTHER COUNTRIES

GEOLOGIC DIVISION
Officer in charge

S. Anthony Stanin ...............

A dd ress

Suite 1001, 150 Causeway St.

2400 Science Parkway, Red Cedar
Research Park.

Rm. 1033, Post Office Bldg.

430 Bounds St.

PO. Box 340; 103 West 10th St.

PO. Box 1696; Rm. 421, Federal
Bldg., 316 North Park Ave.

Rm. 127, Nebraska Hall, 901 North
17th St.

Rm. 229, Federal Bldg., 705 North
Plaza St.

See Massachusetts District Office.

P.O. Box 1238; Rm. 420, Federal
Bldg., 402 East State St.

P.O. Box 4369; Geology Bldg., Univ.
of New Mexico.

PO. Box 1350; Rm. 343, U.S. Post
Office and Courthouse.

P.O. Box 2857; Rm. 440, Century Sta.
Post Office Bldg.

PO. Box 778; Rm. 332, New Federal
Bldg., 3d St. and Rosser Ave.

975 West 3d Ave.

Rm. 621, 201 NW. 3d St.

P.O. Box 3202; 830 NE. Holladay St.

P.O. Box 1107; 4th Floor, Federal
Bldg., 228 Walnut St.

P.O. Box 34168; Bldg. 652, Fort
Buchanan.

See Massachusetts District Office.

Suite 200, 2001 Assembly St.

P.O. Box 1412; Rm. 231, Federal '
Bldg.

Rm. A-413, Federal Bldg., and U.S.
Court House.

Rm. 630, Federal Bldg., 300 East 8th
St.

Rm. 8002, Federal Bldg., 125 South
State St.

See Massachusetts, District Office.

Rm. 304, 200 West Grace St.

Rm. 300, 1305 Tacoma Ave., South.

Rm. 3303, Federal Bldg. and U.S.
Courthouse, 500 Quarrier St., East.

Rm. 200, 1815 University Ave.

P.O. Box 2087; 4015 Warren Ave.

A dd ress

U.S. Geological Survey, USAID/Rio de
_ Janeiro/ENGR, APO New York
09676.

Colombia, Bogota

Indonesia, Bandung

Saudi Arabia, Jiddah

Location

Thailand, Bangkok . .' .............

Location

Kenya, Nairobi ..................

Yemen, San‘a’

' Paul w. Richards

U.S. GEOLOGICAL SURVEY OFFICES

Officer in charge
Maurice M. Brock ................

Thor H. Kiilsgaard

Joseph 0. Morgan

WATER RESOURCES DIVISION

Officer in charge

Neal E. McClymonds

G. Chase Tibbitts, Jr. ............

325

Address

U.S. Geological Survey, USAID, c/o
American Embassy, APO New York
09895.

U.S. Geological Survey, c/o American
Embassy, USAID/ENGR, APO San
Francisco 96356.

U.S. Geological Survey, c/o American
Embassy, APO New York 09697.

Office of Agricultural Development,
USOM--Thailand, APO San
Francisco 96346.

Address

U.S. AID/Nairobi, U.S. Dept. of State,
Washington, DC 20521.

U.S. Geological Survey, USAID/San‘a’,
Agency for International
Development, Washington, DC
20521.

INVESTIGATIONS IN PROGRESS IN THE GEOLOGICAL SURVEY

Investigations in progress during fiscal year 1975 are listed below, together with the names and headquarters of the individuals
in charge of each. Headquarters at main centers are indicated by (NC) for the National Center in Reston, Va., (D) for Denver,
0010., and (M) for Menlo Park, Calif.; headquarters in other cities are indicated by name (see list of offices, p. , for
addresses). Inquiries regarding projects for which no address is given in the list of offices should be directed to the appropriate
Division of the Geological Survey, Reston, Va. 22092. The lowercase letter after the name of the project leader shows the
Division technical responsibility: c, Conservation Division; 1, Land Information Analysis; w, Water Resources Division; no letter,
Geologic Division.

The projects are classified by principal topic. Most geologic-mapping projects involve special studies of stratigraphy, petrology,
geologic structure, or mineral deposits, but are listed only under “Geologic Mapping” unless a special topic or commodity is the
primary justification for the project. A reader interested in investigations of volcanology, for example, should look under the
heading “Geologic Mapping” for projects in areas of volcanic rocks, as well as under the heading “Volcanology.” Likewise, most
water-resources investigations involve special studies of several aspects of hydrology and geology, but are listed only under
“Water Resources” unless a special topic—such as floods or sedimentation—is the primary justification for the project.

Areal geologic mapping is subdivided into mapping at scales smaller than 1 :62,500 (for example, 1:250,000), and mapping at

scales of 1:62,500, or larger (for example, 1224,000).

Abstracts. See Bibliographies and abstracts.
Aluminum:
Resources of the United States (S. H. Patterson, NC)
Analytical chemistry:
Activation analysis (J. J. Rowe, NC)
Analytical methods:
Textural automatic image analyzer research (M. B.
Sawyer, D)
Water chemistry (M. W. Skougstad, w, D)
Analytical services and research (J. I. Dinnin, NC;
C. Huffman, Jr., D; C. O. Ingamells, M)
Assessment of neutron activation methods (V. J. Janzer, w,
D)

Instrumentation (J. F. Abell, NC)

Mineral deposits, characteristic analysis (J. M. Botbol, NC)

Natural organic, macromolecules in water (R. L. Wershaw,
w, D)

Organic geochemistry and infrared analysis (I. A. Breger,
NC)

Organic substances in water (D. F. Goerlitz, w, M)

Plant laboratory support (J. J. Connor, D)

Radioactivation and radiochemistry (H. T. Millard, D)

Reactor support (G. P. Kraker, Jr., w, D)

Rock chemical analysis:

General (D. R. Norton, D)
Rapid (L. Shapiro, NC)

Sample control (Harry Bastron, M)

Services (L. B. Riley, D)

Spectrochemistry (E. L. Mosier, D)

Trace analysis methods, research (F. N. Ward, D)

Ultratrace analysis (H. T. Millard, D)

)g-ray spectrometer for Viking lander (P. Toulmin III, NC)

See also Spectroscopy.

326

Arctic engineering geology (Reuben Kachadoorian, M)
Barite:
Geology, geochemistry, and resources of barite (D. A.
Brobst, NC)
Base metals. See base-metal names.
Bibliographies and abstracts:
Geophysical abstracts (J. W. Clarke, NC)
Lunar bibliography (J. H. Freeberg, M)
Vanadium, geology and resources, bibliography (J. P. Ohl,
D)
Borates:
California:
Furnace Creek area (J. F. McAllister, M)
Searles Lake area (G. I. Smith, M)
Chromite. See Ferro-alloy metals.
Clays:
Bentonite, resource evaluation in Rocky Mountain region
(C. A. Wolfbauer, D)
State:
Georgia, kaolin investigations (S. H. Patterson, NC)
Coal:
Resources of the United States (Paul Averitt, D)
States:
Alaska:
Bering River coal field (R. B. Sanders, c, Anchorage)
Cape Beaufort-Corwin Bluff coal field (J. E. Callahan, c,
Anchorage)
Kukpowruk River coal
Anchorage)
Nenana (C. Wahrhaftig, M)
Colorado:
Brook Cliffs coal field (G. D. Fraser, c, D)
Buckhorn Lakes quadrangle (R. G. Dickinson, c, D)

field (J. E. Callahan, c,

INVESTIGATIONS IN PROGRESS 327

Coal—Continued

States—Continued
Colorado—Continued
Citadel Plateau (G. A. Izett, c, D)
Courthouse Mountain quadrangle (R. G. Dickinson, c, D‘
Danforth Hills area (M. J. Reheis, c, D)
Denver basin, Tertiary coal zone (P. E. Soister, c, D)
Disappointment Valley, eastern (D. E. Ward, D)
Douglas Creek Arch area (B. E. Barnum, c, D)
Little Snake River coal field (C. S. V. Barclay, c, D)
Middle Park—North Park area (G. A. Izett, c, D)
North Park area (D. Hill, c, D)
Savery quadrangle (C. S. V. Barclay, c, D)
Smizer Gulch and Rough Gulch quadrangles (W. J. Hail,
D)
Washboard Rock quadrangle (R. G. Dickinson, c, D)
Watkins and Watkins SE quadrangles (P. E. Soister, c, D)
Yampa coal field (M. E. Brownfield, c, D)
Montana:
Decker quadrangle (B. E. Law, c, Casper, Wyo.)
Hardy quadrangle (K. S. Soward, c, Casper, Wyo.)
Jordan quadrangle (G. D. Mowat, c, Billings)
Monarch quadrangle (B. E. Barnum, c, D)
Pearl School quadrangle (B. E. Law, c, Casper, Wyo.)
Rocky Reef quadrangle (K. S. Soward, c, Casper, Wyo.)
New Mexico:
Gallup East quadrangle (E. D. Patterson, c, Roswell)
Gallup West quadrangle (J. E. Fassett, c, Farmington) '
Manuelito quadrangle (J. E. Fassett, c, Farmington)
Samson Lake quadrangle (J. E. Fassett, c, Farmington)
'fivin Butte quadrangle (J. E. Fassett, c, Farmington)
Western Raton field (C. L. Pillmore, D)
North Dakota:
Clark Butte 15-minute quadrangle (G. D. Mowat, c,
Billings, Mont.)
North Almont quadrangle (H. L. Smith, 0, D)
White Butte 15-minute quadrangle (K. S. Soward, c,
Casper, Wyo.)
Pennsylvania (NC):
Northern anthracite field (M. J. Bergin)
Southern anthracite field (G. H. Wood, Jr.)
Utah (c, D, except as otherwise noted):
Alton coal field (W. E. Bowers)
Basin Canyon quadrangle '(Fred Peterson)
Big Hollow Wash quadrangle (Fred Peterson)
Blackburn Canyon quadrangle (Fred Peterson)
Butler Valley quadrangle (W. E. Bowers)
Canaan Peak quadrangle (W. E. Bowers)
Collet Top quadrangle (H. D. Zeller)
East-of-the-Navajo quadrangle (Fred Peterson)
Fourmile Bench quadrangle (W. E. Bowers)
Horse Mountain quadrangle (W. E. Bowers)
Jessen Butte quadrangle (E. M. Schell, c, Casper, Wyo.)
Kaiparowits Plateau area (H. D. Zeller)
Needle Eye Point quadrangle (H. D. Zeller)
Pete’s Cove quadrangle (H. D. Zeller)
Ship Mountain Point quadrangle (H. D. Zeller)
Sooner Bench quadrangle (Fred Peterson)
Sunset Flat quadrangle (Fred Peterson)
Virginia and West Virginia, Central Appalachian Basin (K. J.
Englund, NC)

Coal-Continued

States—Continued

Wyoming:
Acme quadrangle (B. E. Law, c, Casper)
Alpine quadrangle (H. F. Albee, c, Salt Lake City, Utah)
Appel Butte quadrangle (G. L. Galyardt, c, D)
Bailey Lake quadrangle (M. L. Schroeder, c, D)
Browns Hill quadrangle (C. S. V. Barclay, c, D)
Bull Creek quadrangle (M. L. Schroeder, c, D)
Cottonwood Rim quadrangle (C. S. V. Barclay, c, D)
Coyote Draw quadrangle (G. L. Galyardt, c, D)
Creston Junction quadrangle (R. B. Sanders, c, D)
Deer Creek quadrangle (D. A. Jobin, c, D)
Fortin Draw quadrangle (B. E. Law, c, Casper)
Four Bar-J Ranch quadrangle (G. L. Galyardt, c, D)
Gillette Coal Field (W. L. Rohrer, c, Casper)
Gillette East quadrangle (B. E. Law, c, Casper)
Gillette West quadrangle (B. E. Law, c, Casper)
Greenhill quadrangle (S. P. Buck, c, Casper)
Grieve Reservoir quadrangle (C. S. V. Barclay, c, D)
Hanna Basin area (L. F. Blanchard, c, D)
Kemmerer area (M. L. Schroeder, c, D)
Ketchum Buttes quadrangle (C. S. V. Barclay, c, D)
Little Snake River coal field (C. S. V. Barclay, c, D)
Monarch quadrangle (B. E. Barnum, c, D)
Oil Mountain quadrangle (W. H. Laraway, c, Casper)
Oriba quadrangle (B. E. Law, c, Casper)
Pickle Pass quadrangle (D. A. Jobin, c, D)
Pleasantdale quadrangle (S. L. Grazis, c, D)
Poison Spider quadrangle (W. H. Laraway, c, Casper)
Ranchester quadrangle (B. E. Barnum, c, D)
Rawlins—Baggs area (G. M. Edson, c, D)
Reid Canyon (W. H. Laraway, c, Casper)
Riner quadrangle (R. B. Sanders, c, D)
Rock Springs uplift (P. J. LaPoint, c, D)
Saddlehorse Butte quadrangle (S. L. Grazis, c, D)
Savery quadrangle (C. S. V. Barclay, c, D)
Scraper Reservoir quadrangle (S. L. Grazis, c, D)
Sheridan Pass quadrangle (W. L. Rohr. Rohrer, c, Casper)
Ship Mountain Point quadrangle (H. D. Zeller, c, D)
Stewart Peak quadrangle (D. A. Jobin, c, D)
The Gap quadrangle (G. L. Galyardt, c, D)
The Gap southwest quadrangle (S. L. Grazis, C, D)
Tullis quadrangle (C. S. V. Barclay, c, D)
Weston southwest quadrangle (R. W. Jones, c, Casper)

Construction and terrain problems:

Electronics instrumentation research for engineering
geology (J. B. Bennetti, D)

Engineering geology laboratory (R. A. Farrow, D)

Geotechnical measurements and services (H. W. Olsen, D)

Plowshare special studies (F. W. Stead, D)

Reactor hazards research (K. L. Pierce, D)

Reactor site investigations (R. H. Morris, D)

Regional slope-stability studies, California and Pennsylvania
(D. H. Radbruch-Hall, M)

Research in rock mechanics (F. T. Lee, D)

Sino-Soviet terrain (L. D. Bonham, NC)

Soil engineering research (T. L. Youd, M)

Special intelligence (L. D. Bonham, NC)

Subsurface waste emplacement (Harley Barnes, D)

Volcanic hazards (D. R. Crandell, D)

328

Construction and terrain problems—Continued
States: '
Alaska:
Arctic engineering (George Gryc, M)
Geologic investigations, Amchitka Island (L. M. Gard, Jr.,
D)
California (M):
Geologic environmental maps for land-use planning (E. H.
- Pampeyan, Jr.)
San Francisco Bay sediments, engineering geology studies
(D. R. Nichols, Julius Schlocker)
Colorado (D):
Coal mine deformation studies, Somerset mining district
(C. R. Dunrud)
Engineering geology mapping research, Denver region
(H. E. Simpson)
Massachusetts, sea-cliff erosion studies (C. A. Kaye, Boston)
Nevada (D, except as otherwise noted):
Engineering geophysics, Nevada Test Site (R. D.- Carroll)
Geologic and geomechanical investigations (J. R. Ege)
Geologic effects of nuclear explosions (F. A. McKeown)
Geologic investigations, Nevada Test Site (P. P. Orkild)
Geophysical support, Nevada Test Site (G. D. Bath)
Interpretation of geophysical logs, Nevada Test Site
(R. D. Carroll)
Seismic engineering program (K. W. King, Las Vegas)
Surface effects of nuclear explosions (R. P. Snyder)
Pennsylvania (Carnegie):
Disturbed ground, Allegheny County (R. P. Briggs)
Greater Pittsburgh region (R. P. Briggs)
Landslides, Allegheny County (R.'P. Briggs)
Utah, coal-mine bumps (F. W. Osterwald, D)
See also Urban geology.

Copper:

United States and world resources (D. P. Cox, NC)
States:
Alaska, Southwest Brooks Range (I. L. Tailleur, M)
Arizona, Ray porphyry copper (H. R. Cornwall, M)
Maine and New Hampshire, porphyry, with molybdenum
(R. G. Schmidt, NC)
Michigan:
Greenland and Rockland quadrangles (J. W. Whitlow,
NC)
Michigan copper district (W. S. White, NC)

Crustal studies:

See Earthquake studies; Geophysics, regional.

Earthquake studies:

Active fault analysis (R. E. Wallace, M)

Aftershock studies (R. L. Wesson, M)

Automatic earthquake data processing (S. W. Stewart, M)

Comparative elevation studies (R. 0. Castle, M)

Computer fault modeling (J. H. Dieterich, M)

Computer operations and maintenance (T. C. Jackson, M)

Crustal strain (J. C. Savage, M)

Crustal studies (ARPA) (Isidore Zietz, NC)

Earth structure studies (J. H. Healy, M)

Earthquake field studies (W. J. Spence, C. J. Langer, J. N.
Jordan, M)

Earthquake-induced ground failures (T. L. Youd, M)

Earthquake-induced sedimentary structures (J. D. Sims,
M)

Engineering seismology (W. B. Joyner, M)

Fault-zone geophysical studies (W. H. Jackson, M)

GEOLOGICAL SURVEY RESEARCH 1975

Earthquake studierContinued

Fault-zone tectonics (J. C. Savage, M)

Fluid injection, laboratory investigations (J. D. Byerlee,
Louis Peselnick, M)

Geologic parameters of seismic source areas (F. A.
McKeown, D)

Ground motion studies (R. D. Borcherdt, R. P. Maley, M)

Microearthquake data analysis (W. H. K. Lee, M) ,

National Earthquake Information Service (A. C. Tarr,
Boulder, Colo.)

National Strong-Motion Instrumentation Network (R. B.
Matthiesen, San Francisco, Calif.)

Nicaragua, Central America, technical assistance in
establishing center for earthquake hazard
reduction (P. L. Ward, M)

Plate-tectonic studies (E. D. Jackson, M)

Portable seismic arrays (W. H. Jackson, M)

Reactor-site seismicity (AEC) (W. V. Mickey, D)

Relative activity of multiple fault strands (M. G. Bonilla, M)

Seismic monitoring of dams (W. V. Mickey, D)

Seismic-risk studies (S. T. Algermissen, D)

Seismic-source studies (W. R. Thatcher, M)

Seismicity and Earth structure (J. N. Tagart, D)

Seismicity patterns in time and space (C. G. Bufe, M)

Seismological research observatories (J. R. Peterson,
Albuquerque, N. Mex.)

Soil engineering research (T. L. Youd, M)

Stress studies (C. B. Raleigh, M)

Tectonic studies (W. B. Hamilton, D)

Theoretical seismology (A. F. Espinosa, D)

Worldwide, network of standard seismographs (J. R.
Peterson, Albuquerque, N. Mex.)

States:

Alaska:

Earthquake hazards:

Anchorage (Ernest Dobrovolny, D)

Coastal communities (R. W. Lemke, D)

Juneau (R. D. Miller, D)

Sitka (L. A. Yehle, D)

Southern part (George Plafker, M)

Microearthquake studies (R. A. Page, M)

Turnagain Arm sediments (A. T. Ovenshine, M)
California (M, unless otherwise noted):

Basement rock studies along San Andreas fault (D. C.

Ross)

Central California microearthquake studies (C. G. Bufe)

Continental Shelf fault studies (S. C. Wolf)

Earthquake hazards:

San Francisco Bay region (E. E. Brabb)

Southern part (D. M. Morton, Los Angeles)
Geophysical studies, San Andreas fault (J. H. Healy)
Microearthquake studies:

Central part (R. L. Wesson)

Southern part (D. P. Hill)

New Melones microearthquake studies (J. C. Roller)
Recency of faulting:
Coastal California (E. H. Pampeyan, Jr.)
Eastern Mojave Desert (W. J. Carr, D)
Salton Trough tectonics (R. V. Sharp)
Tectonics:
Central and northern part (W. P. Irwin)
Central San Andreas fault (D. B. Burke, T. W. Dibblee,
Jr.)

INVESTIGATIONS IN PROGRESS

Earthquake studier-Continued
States—Continued
California—Continued
Tectonics—Continued
Southern part (M. M. Clark)
Colorado, Rangely (C. B. Raleigh, M)
Idaho, active faults, Snake River Plain (S. S. Oriel, D)
Missouri, New Madrid fault- -zone geophysics (M F. Kane, D)
Montana, Yellowstone National Park, microearthquake
studies (A. M. Pitt, M)
Nevada, tectonics, western part (E. B. Ekren, D)
New Mexico, seismotectonic analysis, Rio Grande rift (E. H.
Baltz, Jr., D)
South Carolina, microearthquake studies (A. C. Tarr, D)
Utah, earthquake hazards, Salt Lake City (Richard
VanHorn, D)
Washington (M):
Earthquake hazards, Puget Sound region (H. D. Gower,
P. D. Snavely, Jr.)
Hanford microearthquake studies (J. H. Pfluke)
Engineering geologic studies. See Construction and terrain
problems; Urban geology.
Environmental assessment:
Northern Great Plains, methodological guidebook (B. B.
Hanshaw, 1, NC)
South Florida environment (B. F. McPherson, w, Miami)
Environmental geology:
Colorado, mountain soils of the Front Range urban corridor
(K. L. Pierce, D)
Montana, Butte region (H. W. Smedes, D)
Pennsylvania (Carnegie):
Greater Pittsburgh regional studies (R. P. Briggs)
Land-use limitations (R. P. Briggs)
See also Construction and terrain problems; Urban geology.
Evapotranspiration:
Evapotranspiration (F. A. Branson, w, D)
Evapotranspiration data analyses (T. E. A. van Hylckama,
w, Lubbock, Tex.)
Evapotranspiration theory (0. E. Leppanen, w, Phoenix,
Ariz.)
Mechanics of evaporation (G. E. Koberg, w, D)
State.
Arizona, phreatophyte project, Gila River (R. L. Hanson, w,
Tucson)
Extraterrestrial studies:
Lunar analog studies:
Catalogue of terrestrial impact features (M. J. Grolier,
NC)
Channeled scablands (H. G. Wilshire, M)
Ejecta flows (J. F. McCauley, Flagstaff, Ariz.)
Elko craters, Nevada (D. J. Roddy, Flagstaff, Ariz.)
Experimental-shock research (E. C. T. Chao, NC)
Explosion craters (D. J. Roddy, Flagstaff, Ariz.)
Ignimbrites (D. H. Scott, Flagstaff, Ariz.)
Impactite petrology (H. G. Wilshire, M)
Lava ridges and rings (C. A. Hodges, M)
Lonar Lake, India (D. J. Milton, M)
Nevada Test Site (H. J. Moore II, M)
Ries Crater (E. C. T. Chao, NC)
San Francisco volcanic field (E. W. Wolfe,
Ariz.)

Flagstaff,

329

Extraterrestrial studies—Continued
Lunardata synthesis:
Apollo 15-17 photogeology (H. J. Moore, M)
Apollo 17 electromagnetic sounder (R. E. Eggleton,
Flagstaff, Ariz. )
Apollo surface atlas (E. W. Wolfe, Flagstaff, Ariz. )
Color provinces (L. A. Soderblom, Flagstaff, Ariz. )
Dark mantles (B. K. Lucchitta, Flagstaff, Ariz.)
Imbrium and Serenitatis rim geology (E. W. Wolfe,
Flagstaff, Ariz.)
Lunar breccia types (E. C. T. Chao, NC)
Lunar depth gauge (D. B. Stewart, NC)
Lunar geochemical mapping (G. A. Swann, Flagstaff,
Ariz. )
Lunar geologic mapping (D. H. Scott, Flagstaff, Ariz. )
Orientale Basin (J. F. McCauley, Flagstaff, Ariz. )
Sample petrology and stratigraphy (H. G. Wilshire, M)
Scarps and ridges (B. K. Lucchitta, Flagstaff, Ariz.)
Synoptic lunar geology (D. E. Wilhelms, M)
Lunar field geology:
Apollo 11-15 (G. A. Swann, Flagstaff, Ariz.)
Apollo 16, 17 (W. A. Muehlberger, Austin, Tex.)
Lunar sample investigations:
Chemical and X-ray fluorescence analysis (H. J. Rose, Jr.,
NC)
Glass, magnetic properties (F. E. Sentfle, NC)
Impact metamorphism (E. C. T. Chao, NC)
Mass spectrometry (Mitsunobu Tatsumoto, D)
Mineralogical analyses (R. B. Finkelman, NC)
Oxygen fugacities and crystallization sequence (Motoaki
Sato, NC)
Petrographic identification (H. G. Wilshire, M)
Petrologic studies (E. W. Roedder, NC)
Pyroxenes (J. S. Huebner, NC)
Planetary analog studies:
Canyonland development (B. K. Lucchitta, Flagstaff,
Ariz.)
Internal structure of calderas (K. A. Howard, M)
Mass movements (E. C. Morris, Flagstaff, Ariz.)
Peruvian coastal desert (J. F. McCauley, Flagstaff, Ariz.)
Planetary investigations:
Eolian processes (J. F. McCauley, Flagstaff, Ariz.)
Geologic mapping of Mars (D. H. Scott, J. F. McCauley,
Flagstaff, Ariz.)
Geologic synthesis of Mars (Harold Masursky, Flagstaff,

Ariz.)

Image processing studies (L. A. Soderblom, Flagstaff,
Ariz.)

Mariner Jupiter-Saturn (L. A. Soderblom, Flagstaff,
Ariz.)

Mariner Venus-Mercury TV (N. J. Trask, NC)

Mars mineralogy and chemistry-Viking lander (Priestley
Toulmin III, H. J. Rose, Jr., NC)

Mars topographic synthesis (S. S. C. Wu, Flagstaff, Ariz.)

Planetary cartography (R. M. Batson, Flagstaff, Ariz.)

Planetary remote sensing (L. C. Rowan, NC)

Radar applications (G. G. Schaber, Flagstaff, Ariz.)

Viking lander (E. C. Morris, Flagstaff, Ariz. )

Viking orbiter TV (M. H. Carr, M)

Viking- physical properties of Mars (H. J. Moore, M)

Viking site analysis (Harold Masursky, Flagstaff, Ariz.)

330

Ferro-alloy metals:

Chromium resource studies (T. P. Thayer, NC)

Molybdenum, Maine and New Hampshire, with porphyry
cepper (R. G. Schmidt, NC)

Molybdenum-rhenium resource studies (R. U. King, D)

Tungsten, North Carolina, Hamme district (J. E. Gair, NC)

State:

Oregon, John Day area (T. P. Thayer, NC)

Flood characteristics of streams at selected sites:

Alabama, flood studies and bridge-site investigations (C. O.
Ming, w, Montgomery)

Iowa, flood information at selected bridge sites (0. G. Lara,
w, Iowa City)

New Mexico, peak flood-flow characteristics of small
streams (A. G. Scott, w, Santa Fe)

Oregon, flood profiles, Umpqua River and tributaries (D. D.
Harris, w, Portland)

Tennessee (W. J. Randolph, w, Nashville)

Flood discharge from small drainage areas:

Colorado (G. L. Ducret, Jr., w, D)
Connecticut (M. D. Thomas, w, Hartford)
Delaware (R. H. Simmons, w, Dover)

Florida (W. C. Bridges, w, Tallahassee)
Illinois (J. W. Curtis, w, Champaign)
Maryland (D. H. Carpenter, w, College Park)
Massachusetts (C. G. Johnson, Jr., W, Boston)
Minnesota (L. C. Guetzkow, w, St. Paul)
Mississippi (B. E. Colson, w, Jackson)

Rhode Island (C. G. Johnson, Jr., w, Boston, Mass.)
Virginia (E. M. Miller, w, Richmond)

Flood frequency :

Alabama, flood frequency synthesis for small streams (C. O.
Ming, w, Montgomery)

Iowa (0. G. Lara, w, Iowa City)

Kentucky, magnitude and frequency (C. H. Hannum, w,
Louisville)

New Jersey, magnitude and frequency and effect of basin
characteristics (S. J. Stankowski, w, Trenton)

North Carolina, flood frequency and high-flow studies
(N. M. Jackson, Jr., w, Raleigh)

Flood hazard mapping:

United States (E. J. Kennedy, w, NC)
Alabama (J. R. Harkins, w, Tuscaloosa)
Arkansas (M. S. Hines, w, Little Rock)
California (J. R. (hippen, w, M)
Colorado (J. F. McCain, w, D)

Florida (S. D. Leach, w, Tallahassee)
Connecticut (F. H. Ruggles, w, Hartford)
Georgia (McGlone Price, w, Doraville)
Hawaii (C. J. Ewart, w, Honolulu)
Illinois (J. D. Camp, w, Champaign)
Indiana (J. B. Swing, w, Indianapolis)
Louisiana (A. S. Lowe, w, Baton Rouge)
Maine (R. A. Morrill, w, Augusta)
Maryland (W. B. Solley, w, Parkville)
Massachusetts (S. W. Wandle, Jr., w, Boston)
Michigan (R. L. Knutilla, w, Okemos)
Minnesota (L. C. Guetzkow, w, St. Paul)
Mississippi (K. V. Wilson, w, Jackson)
Missouri (E. E. Gann, w, Rolla)

Montana (M. V. Johnson, w, Helena)

GEOLOGICAL SURVEY RESEARCH 1975

Flood hazard mapping—Continued

Nebraska (F. B. Shaffer, w, Lincoln)
Nevada (D. 0. Moore, w, Carson City)

New Hampshire (S. W. Wandle, Jr., w, Boston)
North Carolina (K. L. Lindskov, w, Raleigh)
North Dakota (0. A. Crosby, w, Bismarck)
Oklahoma (W. B. Mills, w, Oklahoma City)
Oregon (D. D. Harris, w, Portland)
Pennsylvania (L. V. Page, w, Harrisburg)
Puerto Rico (W. J. Haire, w, San Juan)
South Carolina (W. T. Utter, w, Columbia)
South Dakota (0. J. Larimer, w, Huron)
Tennessee (C. R. Gamble, w, Nashville)
Texas (J. D. Bohn, w, Austin)

Vermont (S. W. Wandle, Jr., w, Boston)
Virginia (E. M. Miller, w, Richmond)

West Virginia (G. S. Runner, w, Charleston)
Wisconsin (C. L. Lawrence, w, Madison)
Wyoming (J. F. Wilson, Jr., w, Cheyenne)

Flood insurance studies:

Alabama (J. R. Harkins, w, Tuscaloosa)
Arizona (B. N. Aldridge, w, Tucson)
California (J. R. Crippen, w, M)

Colorado (R. U. Grozier, w, D)
Connecticut (M. A. Cervione, w, Hartford)
Florida (S. D. Leach, w, Tallahassee)
Illinois (A. W. Noehre, w, Oak Park)
Indiana (P. B. Rohne, Jr., w, Indianapolis)
Iowa (A. J. Heinitz, w, Iowa City)

Kansas (D. B. Richards, w, Lawrence)
Louisiana (F. N. Lee, w, Baton Rouge)
Michigan (R. L. Knutilla, w, Okemos)
Minnesota (L. C. Guetzkow, w, St. Paul)
Missouri (E. E. Gann, w, Rolla)

Nebraska (G. G. Jamison, w, Lincoln)
New Jersey (E. G. Miller, w, Trenton)
New York (K. I. Darmer, w, Albany)

Ohio (D. K. Roth, w, Columbus)
Oklahoma (T. L. Huntzinger, w, Oklahoma City)
Oregon (D. D. Harris, w, Portland)
Pennsylvania (L. V. Page, w, Harrisburg)
Puerto Rico (W. J. Haire, w, San Juan)
South Carolina (B. H. Whetstone, w, Columbia)
Texas (J. D. Bohn, w, Austin)

Washington (E. G. Nassar, w, Tacoma)
Wisconsin (W. B. Gannon, w, Madison)

Flood-inundation mapping:

Idaho (W. A. Harenberg, w, Boise)
Illinois, northeastern (A. W. Noehre, w, Oak Park)

Flood investigations:

Documentation extreme floods (H. H. Barnes, Jr., w, NC)
States:
Arkansas (M. S. Hines, w, Little Rock)
California, Lake-Playa flood study (M. W. Busby, w, Laguna
Niguel)—
Colorado, flood plain mapping (J. F. McCain, w, D)
Florida (w, Tampa):
Flood hazard evaluation, Myakka River (W. R.
Murphy, Jr.) ,
Flood plain mapping (W. R. Murphy, Jr.)

INVESTIGATIONS IN PROGRESS

Flood investigations—Continued

States—Continued
Georgia, Atlanta, flood characteristics (H. G. Golden, w,
Doraville)
Hawaii, flood gaging (R. H. Nakahaxa, w, Honolulu)
Illinois, flood-depth frequency (J. D. Camp, w, Champaign)
Indiana, flood frequency (L. G. Davis, w, Indianapolis)
Iowa (w, Iowa City):
Flood profiles, statewide (O. G. Lara)
Flood profiles and flood-plain information, Cedar Rapids
(0. G. Lara)
Flood profiles and flood-plain information, Linn County
(0. G. Lara)
Minnesota, flood-plain studies (L. C. Guetzkow, w, St. Paul)
Nebraska, magnitude and frequency of floods (E. W.
Beckman, w, Lincoln)
Nevada (w, Carson City):
Environmental study, western Nevada (P. A. Glancy)
Flood investigations (Lynn Harmsen)
New York, peak discharge of ungaged streams (Bernard
Dunn, w, Albany)
Oklahoma, small watersheds (W. 0. Thomas, Jr., w,
Oklahoma City)
Pennsylvania, flood frequency (H. N. Flippo, Jr., w,
Harrisburg)
South Carolina, flood frequency statewide (B. H.
Whetstone, w, Columbia)
Vermont, floods, small drainage basins (C. G. Johnson, Jr.,
w, Boston)
Virginia, statewide (E. M. Miller, w, Richmond)
Washington, flood-inundation mapping (J. H. Bartells, w,
Tacoma)
Wisconsin, Dane County, flood-inundation study (W. B.
Gannon, w, Madison)
Wyoming, flood investigations (H. W. Lowham, w,
Cheyenne)

Fluorspar :

Colorado, Bonanza, and Poncha Springs quadrangles (R. E.
Van Alstine, NC)

Illinois-Kentucky district, regional structure and ore
controls (D. M. Pinckney, D)

Foreign nations, geologic investigations:

Brazil, mineral resources and geologic training (S. A. Stanin,
Rio de Janeiro)
Earthquake studies (R. L. Wesson, M)
Indonesia:
Dieng geothermal
Bandung/Jakarta)
Geologic mapping and training (P. W. Richards, Bandung)
Short-term applied remote sensing (S. J. Gawarecki,
Jakarta)
Saudi Arabia, crystalline shield, geologic and minerals
reconnaissance (T. H. Kiilsgaard, Jiddah)
Spain, marine mineral resources (P. D. Snavely, Jr., M)
Thailand, remotesensing program (J. 0. Morgan, Bangkok) _

studies (P. W. Richards,

331

Geochemical distribution of the elements—Continued

Cambrian and Ordovician rocks, western United States
(A. T. Miesch, D)

Coding and retrieval of geologic data (T. G. Lovering, D)

Data of geochemistry (Michael Fleischer, NC)

Data of rock analyses (Marjorie Hooker, NC)

Data systems (R. V. Mendes, D)

Dispension of elements in the zone of weathering (R. W.
White, D)

Geochemistry of food plants (H. T. Shacklette, D)

Light stable isotopes (J. R. O’Neil, M)

Metals in volcaniclastic rocks (D. A. Lindsey, D)

Sedimentary rocks, chemical composition (H. A. Tourtelot,
D)

Selenium, tellurium, and thallium, geochemical exploration
(H. W. Lakin, D)

States:

California, Sierra Nevada batholith, geochemical study
(F. C. Dodge, M)

Colorado, Mt. Princeton igneous complex (Priestley
Toulmin III, NC)

Pennsylvania, Greater Pittsburgh region, environmental
geochemistry (R. P. Briggs, Carnegie)

Geochemical prospecting methods:

Application of silver-gold geochemistry to exploration
(H. W. Lakin, D)

Botanical exploration and research (H. L. Cannon, D)

Elements in organic-rich material (F. N. Ward, D)

Exploration for geothermal energy (M. E. Hinkle, D)

Gamma-ray spectrometry (J. A. Pitkin, D)

Geochemical exploration studies with volatile elements
(J. H. McCarthy, D)

Geochemical exploration techniques in alpine and subalpine
environments (G. C. Curtin, D)

Geochemical exploration techniques of the arid
environment (M. A. Chaffee, D)

Instrument development (W. W. Vaughn, D)

Jasperoid—‘relations to ore deposits (T. G. Lovering, D)

Lateritic areas, southern Appalachian Mountains (W. R.
Griffitts, D)

Mercury, geochemistry (A. P. Pierce, D)

Mineral-exploration methods (G. B. Gott, D)

Minor elements in detrital minerals (W. C. Overstreet, D)

Mobile spectrographic laboratory (D. J. Grimes, D)

Ore-deposits controls (A. V. Heyl, Jr., D)

Sulfides, accessory in igneous rocks (G. J. Neuerberg, D)

Trace analyses (J. B. McHugh, D)

States: ,

Idaho, geochemical exploration in Coeur d’Alene (G. B.
Gott, D)

New Mexico, basin and range part, geochemical
reconnaissance (W. R. Griffitts, D)

Geochemistry , experimental:

Environment of ore deposition (P. B. Barton, Jr., NC)
Experimental mineralogy (R. O. Fournier, M)

Foreign nations, hydrologic investigations. See Water
resources, foreign countries.
Fuels, organic. See Coal; Oil shale; Petroleum and natural gas.
Gas, natural. See Petroleum and natural gas.
Geochemical distribution of the elements:
Botanical exploration and research (H. L. Cannon, D)

Fluid inclusions in minerals (E. W. Roedder, NC)
Fluid zonation in metal deposits (J. T. Nash, M)
Geologic thermometry (J. S. Huebner, NC)
Hydrothermal alteration (J. J. Hemley, NC)
Impact metamorphism (E. C. T. Chao, NC)
Kinetics of igneous processes (H. R. Shaw, NC)

332

Geochemistry, experimental-Continued

Late-stage magmatic processes (G. T. Faust, NC)

Mineral equilibria, low-temperature (E-an Zen, NC)

Neutron activation (F. E. Senftle, NC)

Organic geochemistry (J. G. Palacas, D)

Organometallic complexes, geochemistry (Peter Zubovic,
NC)

Solution-mineral equilibria (C. L. Christ, M)

Stable isotopes and ore genesis (R. 0. Rye, D)

Geochemistry, water:

Chemical constituents in groundwater, spatial distribution
(William Back, w, NC)

Chemical reactions at mineral surfaces (J. D. Hem, w, M)

Computer modeling of rock-water interactions (J. L.
Haas, Jr., NC)

Elements, distribution in fluvial and brackish environments
(V. C. Kennedy, w, M)

Factors determining solute transfer in the unsaturated zone
(Jacob Rubin, w, M)

Gases, complexes in water (D. W. Fischer, w, NC)

Geochemistry of geothermal systems (Ivan Barnes, w, M)

Geochemistry of San Francisco Bay waters and sediments
.(D. H. Peterson, w, M)

Geothermal trace element reactions (E. A. Jenne, w, M)

Hydrologic applications of quantitative mineralogy (Robert
Schoen, w, NC)

Hydrosolic metals and related constituents in natural water,
chemistry (J. D. Hem, w, M)

Interaction of minerals and water in saline environments
(B. F. Jones, w, NC)

Mineral-fluid reactions (Ivan Barnes, w, M)

Mineralogic controls of the chemistry of ground water
(B. B. Hanshaw, w, NC)

Organic geochemistry (R. L. Malcolm, w, D)

Trace element partitioning (E. A. Jenne, w, M)

See also Quality of water.

Geochemistry and' petrology, field studies:

Basalt, genesis (T. L. Wright, NC)

Basin and Range granites (D. E. Lee, D)

Environmental geochemistry of western powerplant sites
(J. R. Keith, D)

Epithermal deposits (R. G. Worl, D)

Geochemical halos, Utah-Nevada (R. L. Erickson, D)

Geochemical studies in Southeastern States (Henry Bell III,
NC)

Geochemistry of diagenesis (K. J. Murata, M)

Geochemistry of sediments, San Francisco Bay, Calif. (D. S.
McCulloch, M)

Geochemistry of Tippecanoe Sequence, Western Craton
(L. G. Schultz, D)

Hawaiian ankaramites (M. H. Beeson, M)

Humates, geology and geochemistry, Florida, New Mexico,
and Wyoming (V. E. Swanson, D)

Inclusions in basaltic rocks (E. D. Jackson, M)

Layered Dufek intrusion, Antarctica (A. B. Ford, M)

Layered intrusives (N. J Page, M)

Mercury, geochemistry and occurrence (A. P. Pierce, D)

Niobium and tantalum, distribution in igneous rocks (David

. Gottfried, NC)

Oil shale, organic geochemistry (R. E. Miller, D)

Petrology of the Yellowstone Plateau volcanic field,
Wyoming, Idaho, Montana (R. L. Christiansen, M)

GEOLOGICAL SURVEY RESEARCH 1975

Geochemistry and petrology, field studies—Continued

Rare-earth elements, resources and . geochemistry (J. W.
Adams, D)

Regional metamorphic studies (H. L. James, M)

Residual minor elements in igneous rocks and veins (George
Phair, NC)

Services (P. H. Held, M; H. J. Miller, NC)

Solution transport of heavy metals (G. K. Czamanske, M)

Submarine volcanic rocks, properties (J. G. Moore, M)

Tertiary-Laramide intrusives of Colorado (E. J. Young, D)

Thermal waters, origin and characteristics (D. E. White, M)

Titanium, geochemistry and occurrence (Norman Herz,
Athens, Ga.)

Trondhjemites, major and minor elements, isotopes (Fred
Barker, D)

Ultramafic rocks, petrology of alpine types (R. G. Coleman,
M)

Uranium, radon, and helium—gaseous emanation detection
(G. M. Reimer, D)

Weathering, igneous rocks (R. W. White, D)
Western coal regions:

Geochemical survey of rocks (R. J. Ebens, D)
Geochemical survey of soils (R. R. Tidball, D)
Geochemical survey of vegetation (J. A. Erdman, D)
States:
Alaska:
La Perouse layered intrusion (R. A. Loney, M)
Metasedimentary and metaigneous rocks, Southwestern
Brooks Range (I. L. Tailleur, M)
Arizona (M):
Ray program: ,
Mineral Mountain (T. G. Theodore)
Silicate mineralogy—geochemistry (N. G. Banks)
Stocks (S. C. Creasey)
California:
Kings Canyon National Park (J. G. Moore, M)
Long Valley caldera-Mono Craters volcanic rocks (R. A.
Bailey, NC)
Ritter Range metavolcanic rocks (R. S. Fiske, NC)
Sierra Nevada metamorphism (B. A. Morgan III, NC)
Sierra Nevada xenoliths (J. P. Lockwood, M)
Colorado:
Petrology of the Mt. Princeton igneous complex
(Priestley Toulmin III, NC)
Regional geochemistry—Denver urban area (H. A.
Tourtelot, D)
San Juan volcanic field, east and central (P. W. Lipman,
D)
Idaho, Wood River district (W. E. Hall, M)
Michigan, Sault St. Marie 2-degree quadrangle (J. W.
Whitlow, NC)
Missouri (D):
Geochemical survey of rocks (R. J. Ebens)
Geochemical survey of soils (R. R. Tidball)
Geochemical survey of vegetation (J. A. Erdman)
Montana:
Boulder batholith, structure and petrology (H. W.
Smedes, D)
Diatremes, Missouri River Breaks (B. C. Hearn, Jr., NC)
Geochronology, north-central Montana (B. C. Hearn Jr.,
NC; R. F. Marvin, R. E. Zartman, D)
Wolf Creek area, petrology (R. G. Schmidt, NC)

INVESTIGATIONS IN PROGRESS 333

Geochemistry and petrology, field studies—Continued

States—Continued

Nevada, igneous rocks and related ore deposits (M. -L.
Silberman, M)

New Mexico, Valles Mountains (R. L. Smith, NC)

South Dakota, Keystone pegmatite area (J. J. Norton,
Rapid City)

Geochronological investigations:

Carbon-14 method (Meyer Rubin, NC)

Geochronoldgy—Denver (C. E. Hedge, D)

Geochronology and rock magnetism (G. B. Dalrymple, M)

Geochronology of uranium ores and their host rocks (K. R.
Ludwig, D)

Igneous rocks and deformational periods (R. W. Kistler, M)

Lead-uranium, lead-thorium, and lead—alpha methods (T. W.
Stern, NC)

Magnetic chronology, Colorado Plateau and environs (D. P.
Elston, E. M. Shoemaker, Flagstaff, Ariz.)

Radioactive-disequilibrium studies (J. N. Rosholt, D)

State:

Alaska, K—Ar dates, Southwest Brooks Range (I. L.
Tailleur, M; R. B. Forbes, D. L. Turner,
Fairbanks)

See also Isotope and nuclear studies.

Geologic mapping:

Geologic map of the United States (P. B. King, M)
Map scale smaller than 1 :62,500:
Antarctica:
Dufek Massif and Forrestal Range, Pensacola
Mountains (A. B. Ford, M) ‘
Neptune and Patuxent ranges, Pensacola Mountains
(D. L. Schmidt, D)
Belt basin study (J. E. Harrison, D)
Columbia River basalt (D. A. Swanson, M)
States:
Alaska (M, except as otherwise noted):
Ambler River and Baird Mountains quadrangles (I. L.
Tailleur, M)
Charley River quadrangle (E. E. Brabb)
Compilations of Alaska geology (E. H. Lathram)
Craig quadrangle (G. D. Eberlein, Michael Churkin, Jr.)
Delong Mountains quadrangle (I. L. Tailleur)
Geologic map (H. M. Beikman)
Geology of Alaska (George Gryc)
Glacier Bay National Monument (D. A. Brew)
Hughes-Shungnak area (W. W. Patton, Jr.)
Iliamna quadrangle (R. L. Detterman)
Juneau and Taku River quadrangles (D. A. Brew)
Metamorphic facies map (D. A. Brew)
Natural landmarks investigation (R. L. Detterman)
Northern part, petroleum investigations (George Gryc)
St. Lawrence Island (W. W. Patton, Jr.)
Tracy Arm-Fords Terror (Thundering Fiords)
Wilderness study area (D. A. Brew)
Arizona (Flagstaff):
North-central part (D. P. Elston)
Phoenix 2-degree quadrangle (T. N. V. Karlstrom)
Shivwits Plateau (Ivo Lucchitta)
Arkansas (B. R. Haley, Little Rock)
Colorado (D):
Denver 2-degree quadrangle (B. H. Bryant)

Geologic mapping-Continued

Map scale smaller than 1162,500—Continued
States—Continued
Colorado—Continued
Geologic map (0. L. Tweto)
Leadville 2-degree quadrangle (O. L. Tweto)
Montrose 2-degree quadrangle (W. J. Hail, Jr.)
Pueblo 2-degree quadrangle (G. R. Scott)
Sterling 2-degree quadrangle (J. A. Sharps)
Idaho (D, except as otherwise noted):
Challis Volcanics (D. H. McIntyre)
Dubois 2-degree quadrangle (D. L. Schleicher)
Idaho Falls 2-degree quadrangle (D. L. Schleicher)
Preston 2—degree quadrangle (S. S. Oriel)
Snake River plain, central part, volcanic petrology
(H. E. Malde)
Snake River plain region, eastern part (S. S. Oriel)
Spokane-Wallace region (A. B. Griggs, M)
Montana:
Butte 2-degree quadrangle (M. R. Klepper, NC)
Spokane-Wallace region (A. B. Griggs, M)
Nevada:
Elko County (R. A. Hope, M)
Elko County, central (K. B. Ketner, D)
Elko County, western (R. R. Coats, M)
Geologic map (J. H. Stewart, M)
Nevada Test Site geologic investigations (P. P. Orkild,
D)
New Mexico (D):
North Church Rock area (A. R. Kirk)
Sanostee (A. C. Huffman, Jr.)
Socorro 2-degree quadrangle (G. O. Bachman)
West half of Santa Fe 2-degree quadrangle (E. H. Baltz,
Jr.)
Pennsylvania, Greater Pittsburgh region geology (W. R.
Wagner, Carnegie)
Utah:
Delta 2-degree quadrangle (H. T. Morris, M)
Glen Canyon Recreation Area (A. L. Brokaw, D)
Tooele 2-degree quadrangle (W. J. Moore, M)
Washington, Spokane-Wallace region (A. B. Griggs, M)
Wyoming: ,
Geologic map (J. D. Love, D)
Preston 2-degree quadrangle (S. S. Oriel, D)
Map scale 1:62,500, and larger:
States and territories:
Alaska:
Anatuvuk Pass (R. B. Sanders, c, Anchorage)
Anchorage area (Ernest Dobrovolny, D)
Bering River coal field (R. B. Sanders, c, Anchorage)
Cape Beaufort-Corwin Bluffs coal field (J. E. Callahan,
c, Anchorage)
Geology and mineral resources of the Ketchikan
quadrangle (H. C. Berg, M)
Juneau area (R. D. Miller, D)
Kukpowruk River coal field (J. E. Callahan, c,
Anchorage)
Nelchina area Mesozoic investigations (Arthur Grantz,
M)
Nenana coal investigations (Clyde Wahrhaftig, M)
Nome area (C. L. Hummel, M)

334 GEOLOGICAL SURVEY RESEARCH 1975

Geologic mapping—Continued
Map scale 1:62,500 and larger—Continued

Geologic mapping—Continued
Map scale 1162,500 and larger—Continued

States and territories—Continued
Arizona:
Bowie zeolite area (L. H. Godwin, c, NC)
Cochise County, southern part (P. T. Hayes, D)
Cummings Mesa quadrangle (Fred Peterson, c, D)
Garnet Mountain quadrangle (P. M. Blacet, M)
Hackberry Mountain area (D. P. Elston, Flagstaff)
Mt. Wrightson quadrangle (H. D. Drewes, D)
Ray district, porphyry copper (H. R. Cornwall, M)
Sedona area (D. P. Elston, Flagstaff)
California (M, except as otherwise noted):
Coast Range, ultramafic rocks (E. H. Bailey)
Condrey Mountain-Hornbrook quadrangle (P. E. Hotz)
Geysers-Clear Lake area (R. J. McLaughlin)
Long Valley caldera (R. A. Bailey, NC)
Malibu Beach and Topanga quadrangles (R. F. Yerkes)
Merced Peak quadrangle (D. L. Peck, NC)
Palo Alto, San Mateo, and Montara Mountain
quadrangles (E. H. Pampeyan)
Point Dume and Triunfo Pass quadrangles (R. H.
Campbell)
Ryan quadrangle (J. F. McAllister)
Searles Lake area (G. I. Smith)
Sierra Nevada batholith (P. C. Bateman)
Colorado:
Barcus Creek quadrangle (W. J. Hail, D)
Barcus Creek SE quadrangle (W. J. Hail, D)
Bonanza quadrangle (R. E. Van Alstine, NC)
Buckhorn Lakes quadrangle (R. G. Dickinson, 0, D)
Central City area (R. B. Taylor, D)
Citadel Plateau (G. A. Izett, c, D)
Coal mine deformation studies, Somerset mining
district (C. R. Dunrud, D)
Cochetopa area (J. C. Olson, D)
Courthouse Mountain quadrangle (R. G. Dickinson, c,
D)
Denver basin, Tertiary coal zone (P. E. Soister, c, D)
Denver metropolitan area (R. M. Lindvall, D)
Disappointment Valley, geology and coal resource
(D. E. Ward, D)
Front Range, northeastern part, Fort Collins area
(W. A. Braddock, D)
Indian Hills Precambrian (B. H. Bryant, D)
Lake City caldera (P. W. Lipman, D)
Middle Park—North Park area (G. A. Izett, c, D)
Northern Park Range (G. L. Snyder, D)
Philadelphia Creek quadrangle (B. E. Barnum, c, D)
Platoro caldera and related volcanic rocks,
southeastern San Juan Mountains (P. W. Lipman,
D)
Poncha Springs quadrangle (R. E. Van Alstine, NC)
Rangely NE quadrangle (H. L. Cullins, c, Metairie, La.)
Rough Gulch quadrangle (W. J. Hail, D)
San Juan mining area (R. G. Luedke, NC)
Savery quadrangle (C. S. V. Barclay, c, D)
Smizer Gulch quadrangle (W. J. Hail, D)
Strasburg SW quadrangle (P. E. Soister, c, D)
Thornburgh quadrangle (M. J. Reheis, c, D)
Ward and Gold Hill quadrangles (D. J. Gable, D)
Washboard Rock quadrangle (R. G. Dickinson, c, D)

States and territories—Con tinued
Colorado—Continued
Watkins and Watkins SE quadrangles (P. E. Soister, c,
D)
Connecticut:
Cooperative mapping program (M. H. Pease, Jr.,
Boston, Mass.)
Taconic sequence (E-an Zen, NC)
Florida, Attapulgus-Thomasville area, fuller’s earth
deposits (S. H. Patterson, NC)
Idaho:
Alpine quadrangle (H. F. Albee, c, Salt Lake City,
Utah)
Bayhorse area (S. W. Hobbs, D)
Boulder Mountains (C. M. Tschanz, D)
Goat Mountain quadrangle (M. H. Staatz, D)
Grouse quadrangle (B. A. Skipp, D)
Hawley Mountain quadrangle (W. J. Mapel, D)
Malad southeast quadrangle (S. S. Oriel, D)
Montour quadrangle (H. E. Malde, D)
Palisades Dam quadrangle (D. A. Jobin, c, D)
Patterson quadrangle (E. T. Ruppel, D)
Poker Peak quadrangle (H. F. Albee, 0, Salt Lake City,
Utah)
Upper and Lower Red Rock Lakes quadrangles (I. J.
Witkind, D)
Wood River district (W. E. Hall, M)
Yellow Pine quadrangle (B. F. Leonard, D)
Indiana: >
Ohio River Quaternary (M. P. Weiss, DeKalb, Ill.)
Ohio River valley, Quaternary geology (L. L. Ray, NC)
Kentucky, cooperative mapping program (D. W. Olive,
Lexington)
Maine (NC, except as'otherwise noted):
Blue Hill quadrangle (D. B. Stewart)
Castine quadrangle (D. B. Stewart)
Chain Lakes area (E. L. Boudette)
Orland quadrangle (D. R. Wones)
Rumford quadrangle (R. H. Moench, D)
The Forks quadrangle (F. C. Canney, D)
Maryland (NC):
Delmarva Peninsula (J. P. Owens)
Northern Coastal Plain (J. P. Minard)
Western Maryland Piedmont (M. W. Higgins)
Massachusetts (Boston, except as otherwise noted):
Boston and vicinity (C. A. Kaye)
Cooperative mapping program (M. H. Pease, Jr.)
Taconic sequence (E-an Zen, NC)
Michigan (NC):
Gogebic Range, western part (R. G. Schmidt)
Wakefield quadrangle (W. C. Prinz)
Montana:
Bearpaw Mountains, petrology (B. C. Hearn, Jr., NC)
Boulder Batholith region (H. W. Smedes, D)
Butte North quadrangle (H. W. Smedes, D)
Cooke City quadrangle (J. E. Elliott, D)
Craig quadrangle (R. G. Schmidt, NC)
Crazy Mountains Basin (B. A. Skipp, D)
Decker quadrangle (B. E. Law, c, Casper, Wyo.)
Diatremes, Missouri River Breaks (B. C. Hearn, Jr., NC)

INVESTIGATIONS IN PROGRESS 335

Geologic mapping—Continued

Geologic mapping—Continued
Map scale 1262,500 and larger—Continued

Map scale 1 :62,500 and larger—Continued

States and territories—Continued
Montana—Continued
Elk Park quadrangle (H. W. Smedes, D)
Hardy quadrangle (K. S. Soward, c, Casper, Wyo.)
Jordan quadrangle (G. D. Mowat, c, Billings)
Lemhi Pass quadrangle (M. H. Staatz, D)
Melrose phosphate field (G. D. Fraser, c, D)
Monarch quadrangle (B. E. Barnum, c, D)
Northern Pioneer Range, geologic environment
(E-an Zen, NC)
Pearl School quadrangle (G. L. Galyardt, c, Casper,
Wyo.)
Rocky Reef quadrangle (K. S. Soward, c, Casper,
Wyo.)
Wickiup Creek quadrangle (H. W. Smedes, D)
Wolf Creek area, petrology (R. G. Schmidt, NC)
Nevada:
Austin quadrangle (E. H. McKee, M)
Bellevue Peak quadrangle (T. B. Nolan, NC)
Carlin region (J. F. Smith, Jr., D)
Jordan Meadow and Disaster Peak quadrangles (R. C.
Greene, M) .
Kobeh Valley (T. B. Nolan, NC; C. W. Merriam, M)
Midas-Jarbidge area (R. R. Coats, M)
Pinto Summit quadrangle (T. B. Nolan, NC)
Spruce Mountain 4 quadrangle (G. D. Fraser, c, D)
New Hampshire, cooperative mapping program, surficial
(Carl Koteff, Boston, Mass.)
New Mexico:
Acoma area (C. H. Maxwell, D)
Apache Springs and Galisteo quadrangles (R. B.
Johnson, D)
Church Rock-Smith Lake (C. T. Pierson, D)
Cretaceous stratigraphy, San Juan basin (E. R. Landis,
D)
Gallup East quadrangle (E. D. Patterson, c, Roswell)
Gallup West quadrangle (J. E. Fassett, c, Farmington)
Hillsboro quadrangle (D. C. Hedlund, D)
Iron Mountain (A. V. Heyl, Jr., D)
Manuelito quadrangle (J. E. Fassett, c, Farmington)
Manzano Mountains (D. A. Myers, D)
Pinos Altos Range (T. L. Finnell, D)
Raton coal basin, western part (C. L. Pillmore, D)
Samson Lake quadrangle (J. E. Fassett, c, Farming-ton)
Twin Butte quadrangle (J. E. Fassett, c, Farmington)
Valles Mountains, petrology (R. L. Smith, NC)
New York (NC):
Pope Mills and Richville quadrangles (C. E. Brown)
Taconic sequence (E-an Zen)
North Carolina, Central Piedmont (A. A. Stromquist, D)
North Dakota:
Clark Butte 15-minute quadrangle (G. D. Mowat, c,
Billings, Mont.)
North Almont quadrangle (H. L. Smith, c, D)
White Butte 15-minute quadrangle (K. S. Soward, c,
Casper, Wyo.)
Pennsylvania (NC):
Claysville—Avella area (S. P. Schweinfurth)
Northern anthracite field (M. J. Bergin)
Southern anthracite field (G. H. Wood, Jr.)

States and territories—Continued
Pennsylvania—Continued
Western middle anthracite field (H. H. Arndt)
Wind Gap and adjacent quadrangles (J. B. Epstein)
Puerto Rico (J. M. Aaron, San Juan)
South Dakota:
Black Hills Precambrian (J. A. Redden, Hill City)
Keystone Pegmatite area (J. J. Norton, NC)
Rapid City area (J. M. Cattermole, D)
Texas, Tilden-Loma Alta area (K. A. Dickinson, D)
Utah:
Basin Canyon quadrangle (Fred Peterson, c, D)
Big Hollow Wash quadrangle (Fred Peterson, c, D)
Blackburn Canyon quadrangle (Fred Peterson, c, D)
Butler Valley quadrangle (W. E. Bowers, c, D)
Canaan Peak quadrangle (W. E. Bowers, c, D)
Coal-mine bumps, Sunnyside mining district (F. W.
Osterwald, D)
Collet Top quadrangle (H. D. Zeller, c, D)
Confusion Range (R. K. Hose, M)
Crawford Mountains (W. C. Gere, c, M)
East-of-the-Navajo quadrangle (Fred Peterson, c, D)
Fourmile Bench quadrangle (W. E. Bowers, c, D)
Horse Mountain quadrangle (W. E. Bowers, c, D)
Jessen Butte quadrangle (E. M. Schell, c, Casper, Wyo.)
Matlin Mountains (V. R. Todd, M)
Needle Eye Point quadrangle (H. D. Zeller, c, D)
Oak City area (D. J. Varnes, D)
Ogden 4 NW quadrangle (R. J. Hite, c, D)
Pete’s Cove quadrangle (H. D. Zeller, c, D)
Salt Lake City and vicinity (Richard VanHorn, D)
Seep Flat quadrangle (E. V. Stephens, c, M)
Sheeprock Mountains, West Tintic district (H. T.
Morris, M) ,
Ship Mountain Point quadrangle (H. D. Zeller, c, D)
Sooner Bench quadrangle (Fred Peterson, c, D)
Sunset Flat quadrangle (Fred Peterson, c, D)
Upper Valley quadrangle (W. E. Bowers, c, D)
Wah Wah Summit quadrangle (L. F. Hintze, Salt Lake
City) '
Wide Hollow Reservoir (E. V. Stephens, c, M)
Willard Peak area (M. D. Crittenden, Jr., M)
Virginia (NC):
Culpepper Basin (K. Y. Lee)
Delmarva Peninsula (J. P. Owens)
Northern Blue Ridge (G. H. Espenshade)
Rapidan-Rappahannock (Louis Pavlides)
Washington:
Chewelah No. 4 quadrangle (F. K. Miller, M)
Glacier Park area (F. W. Cater, D)
Loomis quadrangle (C. D.'Rinehart, M)
Olympic Peninsula, eastern part (W. M. Cady, D)
Olympic Peninsula, northwestern part (P. D. Snavely,
Jr., M)
Stevens County (R. G. Yates, M)
Wisconsin:
Black River Falls and Hatfield quadrangles (Harry
Klemic, NC)
Lead-zinc district (W. S. West, Platteville)

336

Geologic mapping—Continued

Map scale 1 :62,500 and larger—Continued
States and territories—Continued
Wyoming:

Acme quadrangle (B. E. Law, 0, Casper)

Albany and Keystone quadrangles (M. E. McCallum,
Fort Collins, Colo.)

Alkali Butte quadrangle (M. W. Reynolds, D)

Alpine quadrangle (H. F. Albee, c, Salt Lake City,
'Utah)

Appel Butte quadrangle (G. L. Galyardt, c, D)

Badwater Creek (R. E. Thaden, D)

Bailey Lake quadrangle (M. L. Schroeder, c, D)

Browns Hill quadrangle (C. S. V. Barclay, c, D)

Bull Creek quadrangle (M. L. Schroeder, c, D)

Camp Davis quadrangle (M. L. Schroeder, c, D)

Cottonwood Rim quadrangle (C. S. V. Barclay, c, D)

Coyote Draw quadrangle (G. L. Galyardt, c, D)

Crawford Mountains (W. C. Gere, c, M)

Creston Junction quadrangle (R. B. Sanders, c, D)

Deer Creek quadrangle (D. A. Jobin, c, D)

Devils Tooth quadrangle (W. G. Pierce, M)

Four Bar—J Ranch quadrangle (G. L. Galyardt, c, D)

Gillette Coal Field (W. L. Rohrer, c, Casper)

Greenhill quadrangle (S. P. Buck, c, Casper)

Grieve Reservoir quadrangle (C. S. V. Barclay, c, D)

Ketchum Buttes quadrangle (C. S. V. Barclay, c, D)

Monarch quadrangle (B. E. Barnum, c, D)

Oil Mountain quadrangle (W. H. Laraway, c, Casper)

Oriba quadrangle (B. E. Law, c,‘ Casper)

Pickle Pass quadrangle (D. A. Jobin, c, D)

Pine Creek quadrangle (D. A. Jobin, c, D)

Pleasantdale quadrangle (S. L. Grazis, c, D)

Poison Spider quadrangle (W. H. Laraway, c, Casper)

Ranchester quadrangle (B. E. Barnum, c, D)

Reid Canyon quadrangle (W. H. Laraway, c, Casper)

Riner quadrangle (R. B. Sanders, c, D)

Saddlehorse Butte quadrangle (S. L. Grazis, c, D)

Savery quadrangle (C. S. V. Barclay, c, D)

Scraper Reservoir quadrangle (S. L. Grazis, c, D)

Sheridan Pass quadrangle (W. L. Rohrer, c, Casper)

Ship Mountain Point quadrangle (H. D. Zeller, c, D)

Square Top Butte quadrangle (W. H. Laraway, c,
Casper)

Stewart Peak quadrangle (D. A. Jobin, c, D)

The Gap quadrangle (G. L. Galyardt, c, D)

The Gap southwest quadrangle (S. L. Grazis, c, D)

Tullis quadrangle (C. S. V. Barclay, c, D)

Wapiti quadrangle (W. G. Pierce, M)

Weston southwest quadrangle (R. W. Jones, c, Casper)

Geomagnetism (D):

External geomagnetic-field variations (W. H. Campbell)
Geomagnetic-data analysis (C. O. Stearns)
Geomagnetic observatories (J. D. Wood)

Geomagnetic secular variation (L. R. Alldredge)
Magnetic-field analysis and U.S. charts (E. B. Fabiano)
World magnetic charts and analysis (E. B. Fabiano)

Geomorphology:

Channel adjustment, Cochiti Dam (J. D. Dewey, w,
Albuquerque, N. Mex.)
Forest geomorphology, Pacific coast (R. J. Janda, w, M)

GEOLOGICAL SURVEY RESEARCH 1975

Geomorphology—Continued

Morphology, provenance, and movement of desert sand
(E. D. McKee, D)

Ohio River Quaternary (M. P. Weiss, DeKalb, Ill.)

Ohio River Valley, geologic development (L. L. Ray, NC)

Stream channelization (J. C. Brice, w, M)

Studies of erosion control (N. J. King, w, D)

Quaternary landforms and deposits interpreted from
Landsat-1 imagery, midwest and Great Plains
(R. B. Morrison, D)

States:

Arizona, post-1890 A.D. erosion features interpreted from
Landsat-1 imagery (R. B. Morrison, D)

Colorado, mountain soils, regolith (K. L. Pierce, D)

Idaho, eastern Snake River plain, Quaternary geology (E. T.
Ruppel, D)

Indiana, Ohio River Quaternary (M. P. Weiss, Dekalb, Ill.)

Massachusetts, sea-cliff erosion studies (C. A. Kaye, Boston)

New Mexico, Chaco Canyon National Monument (H. E.
Malde, D)

Oregon, coastal sedimentation (R. J. Janda, w, M)

Wyoming (D):

Wind River Mountains, Quaternary geology (G. M.
Richmond)
Yellowstone National Park, glacial and postglacial

geology (G. M. Richmond)

See also Sedimentology; Geochronological investigations.

Geophysics, regional:

Airborne and satellite research:
Aeromagnetic studies (M. F. Kane, D)
Electromagnetic research (F. C. Frischknecht, D)
Gamma radioactivity studies (J. A. Pitkin, D)
Regional studies (Isidore Zietz, NC)
Satellite magnetometry (R. D. Regan, NC)
Antarctica, Pensacola Mountains, geophysical studies (J. C.
Behrendt, Woods Hole, Mass.)
Basin and Range, geophysical studies (W. E. Davis, M)
Crust and upper mantle:
Aeromagnetic interpretation of metamorphic rocks
(Isidore Zietz, NC)
Aeromagnetic studies of the United States (Isidore Zietz,
NC)
Analysis of traveltime data (J. C. Roller, M)
Fault-zone geophysical studies (W. H. Jackson, M)
Seismicity and Earth structure (J. N. Taggart, Boulder,
Colo.)
Seismologic studies (J. P. Eaton, M)
Engineering geophysics (H. D. Ackermann, D)
Florida Continental Shelf, gravity studies (H. L. Krivoy,
Corpus Christi, Tex.)
Gravity survey, Maryland cooperative (D. L. Daniels, NC)
Ground-water geophysics (W. D. Stanley, D)
Magnetic chronology, Colorado Plateau and environs (D. P.
Elston, E. M. Shoemaker, Flagstaff, Ariz.)
Mobile magnetometer profiles, eastern United States (M. F.
Kane, D)
National aeromagnetic survey (J. R. Henderson, D)
New England, magnetic properties of rocks (Andrew
Griscom, M)
Program and systems development (G. I. Evenden, W. L.
Anderson, D)

INVESTIGATIONS IN PROGRESS 337

Geophysics, regional-Continued

Rocky Mountains, northern (D. L. Peterson, M. D.
Kleinkopf, D)
Southeastern States geophysical studies (Peter Popenoe,

NC)
Southwestern States geophysical studies (D. L. Peterson,
NC)
Ultramafic rocks, geophysical studies, intrusions (G. A.
Thompson, M)

United States, aeromagnetic surveys (E. R. King, NC)
Yellowstone National Park, geophysical study (H. R. Blank,
Eugene, Oreg.)
States and territories:
Alaska, Ambler River and Baird Mountains quadrangles
gravity (D. F. Barnes, M)
California, Sierra Nevada, geophysical studies (H. W. Oliver,
M)
Idaho, Snake River Plain (D. L. Peterson, D)
Maryland, Cooperative Survey (J. L. Meuschke, D)
Massachusetts :
Cooperative survey (J. L. Meuschke, D)
Geophysical studies (M. F. Kane, NC)
Minnesota (NC):
Keweenawan rocks, magnetic studies (K. G. Books)
Southern part, aeromagnetic survey (E. R. King)
Nevada (D):
Applied geophysics, Nevada Test Site (G. D. Bath)
Engineering geophysics, Nevada Test Site (R. D. Carroll)
New Mexico, Rio Grande graben (L. E. Cordell, D)
Pennsylvania, magnetic properties of rocks (Andrew
Griscom, M)
Puerto Rico, seismicity of Puerto Rico (A. C. Tarr, D)

Geophysics, theoretical and experimental:

California, mass properties of oil field rocks (L. A. Beyer,
M)

Crustal studies (ARPA) (Isidore Zietz, NC)

Earth structure studies (J. H. Healy, M)

Earthquakes, local seismic studies (J. P. Eaton, M)

Elastic and inelastic properties of Earth materials (Louis
Peselnick, M)

Electrical properties of rocks (R. D. Carroll, D)

Electrical resistivity studies (A. A. R. Zohdy, D)

Experimental rock mechanics (C. B. Raleigh, M)

Gamma-ray spectrometry (J. A. Pitkin, D)

Geophysical data, interpretation using electronic computers
(R. G. Henderson, NC) .

Geophysical program and systems development (G. E.
Andreasen, NC)

Ground motion studies (J. H. Healy, M)

Infrared and ultraviolet radiation studies (R. M. Moxham,
NC)

In-situ stress (R. V. de la Cruz, M)

Interpretation of geophysical logs, Nevada Test Site (R. D.
Carroll, D)

Magnetic and luminescent properties (F. E. Senftle, NC)

Magnetic model studies (G. E. Andreasen, NC)

Magnetic properties laboratory (M. E. Beck, Jr., Bellingham,
Wash.)

Microwave studies (A. W. England, D)

Paleomagnetism, Precambrian and Tertiary chronology
(D. P. Elston, Flagstaff, Ariz.) » -

Remanent magnetization of rocks (C. S. Grommé, M)

Geophysics, theoretical and experimental—Continued

Resistivity interpretation (A. A. R. Zohdy, D)

Rock behavior at high temperature and pressure (E. C.
Robertson, NC)

Seismicity patterns in time and space (C. G. Bufe, M)

Stress studies (C. B. Raleigh, M)

Thermodynamic properties of rocks (R. A. Robie, NC)

Ultramafic intrusions, geophysical studies (G. A. Thompson,
M)

Volcano geophysics (E. T. Endo, M)

Geothermal investigations:

Energy transport in ground water (A. F. Moench, w, M)
Geochemical exploration (M. E. Hinkle, D)
Geochemical indicators (A. H. ’I‘ruesdell, M)
Geothermal geophysics (D. R. Mabey, D)
Geothermal hydrologic reconnaissance (F. H. Olmsted, w, _
M) '
Geothermal studies (A. H. Lachenbruch, M)
Heat flow (J. H. Sass, A. H. Lachenbruch, M)
Oxygen isotopes (J. R. O’Neil, M)
Physics of geothermal systems (W. H. Diment, M)
Regional volcanology (R. L. Smith, NC) '
Remote sensing (Kenneth Watson, D)
Rio Grande geothermal (P. H. Jones, w, Bay St. Louis,
Miss.)
Rock-water interactions (R. O. Fournier, M)
Seismic exploration (P. L. Ward, M)
Thermal waters (D. E. White, M)
States:
Alaska, geothermal reconnaissance (T. D. Miller, M)
Arizona, geothermal consultation (T. W. Anderson, w,
Flagstaff)
California:
Clear Lake-Geysers area (B. C. Hearn, Jr., NC)
Clear Lake-Geysers microearthquake monitoring (C. G.
Bufe, M)
Geology of Long Valley-Mono Basin (R. A. Bailey, NC)
Imperial Valley geothermal (J. J. French, w, Garden
Grove)
Imperial Valley microearthquake monitoring (D. P. Hill,
M)
Long Valley active seismology (D. P. Hill, M)
Long Valley hydrology (R. E. Lewis, w, Laguna Niguel)
Pre-Tertiary geology of The Geysers-Clear Lake area
(R. J. McLaughlin, M)
Seismic noise, The Geysers area (H. M. Iyer, M)
Colorado:
Colorado geothermal (M. S. Bedinger, w, D)
Geothermal resources (G. L. Galyardt, c, D)
Idaho (w, Boise):
Geothermal resources (H. W. Young)
Test drilling, Raft River valley (E. G. Crosthwaite)
Nevada, geothermal reconnaissance (R. K. Hose, M)
Oregon:
Geothermal reconnaissance (N. S. MacLeod, M)
Hydrologic reconnaissance of geothermal areas (E. A.
Sammel, w, M)
Utah, geothermal resources (J. E. Smedley, 0, Salt Lake
City)
Wyoming, Yellowstone thermal areas, geology (L. J. P.
Muffler, M) '

338

Glacial geology, Antarctica, Pensacola Mountains (D. L.
Schmidt, D)

Glaciology :

Glaciological research, International Hydrological Decade
(M. F. Meier, w, Tacoma, Wash.)

Sea-ice dynamics (W. J. Campbell, w, Tacoma, Wash.)
Water, ice, and energy balance of mountain glaciers, and ice
physics (M. F. Meier, w, Tacoma, Wash.)

World Data Center A -- glaciology (M. F. Meier, w, Tacoma,
Wash.)

State:

Alaska (L. R. Mayo, w, Fairbanks)

Gold :

Composition related to exploration (J. C. Antweiler, D)
Gold resources of the United States (W. C. Prinz, NC; F. S.
Simons, D) .

Great Lakes region (D. A. Seeland, D)
Placer deposits, New Mexico (Kenneth Segerstrom, D)
States:
Alaska (M):

Gulf of Alaska, nearshore (E. H. Lathram)

Seward Peninsula, nearshore (D. M. Hopkins)
Arizona, Gold Basin-Lost Basin district (P. M. Blacet, M)
California, Klamath Mountains (P. E. Hotz, M)
Montana (D):

Confederate Gulch (W. B. Myers)

Cooke City quadrangle (J. E. Elliott)

Southwestern part, ore deposits (K. L. Wier)
Nevada (M):

Aurora and Bodie districts, Nevada-California (F. J.

Kleinhampl)

Carlin mine (A. S. Radtke)

Comstock district (D. H. Whitebread)

Dun Glen quadrangle (D. H. Whitebread)

Goldfield district (R. P. Ashley)
North Carolina, Gold Hill area (A. A. Stromquist, D)
Oregon-Washington, nearshore area (P. D. Snavely, Jr., M)
South Dakota, Keystone area (W. H. Raymond, D)
Wyoming:

Northwestern part, conglomerates (J. C. Antweiler, D)
See also Heavy metals.

Ground water-surface water relations:

Bank storage reconnaissance (W. D. Simons, w, M)
States:
California:
Confined aquifer, San Bernardino (J. S. Singer, w, Laguna
Niguel)
Tuolumne gas wells (R. W. Page, w, Sacramento)
Florida (w, Miami, except as otherwise noted):
Biscayne aquifer analog model (E. H. Cordes)
Hydrologic base, Dade County (J. E. Hull)
' Miami Canal infiltration (F. W. Meyer)
Well fields, west-central Florida (E. R. Close, w, Tampa)
Idaho (w, Boise):
Hydrology:
Island Park—Henrys Lake (R. L. Whitehead)
Weiser Basin (H. W. Young)
Minnesota, sewage treatment and lake quality (R. J. Wolf,
w, St. Paul)
Missouri, hydrology of Ozarks Basins (John Skelton, w,
Rolla)

GEOLOGICAL SURVEY RESEARCH 1975

Ground water-surface water relations—Continued

States—Continued

Nebraska, Platte Basin water resources (E. G. Lappala, w,
Lincoln)

New Mexico, Pecos River-miscellaneous (G. E. Welder, w,
Roswell)

North Carolina, effect of channel improvement on
hydrologic conditions in Creeping Swamp (M. D.
Winner, w, Raleigh)
Ohio, Franklin County digital model (R. E. Fidler, w,
Columbus)
Pennsylvania, level monitoring, Matamoras (W. C. Roth, w,
Harrisburg)
Rhode Island, hydrology, Branch Blackstone (H. E.
Johnston, w, Providence)
Washington, Water Yakima Reservation (D. O. Gregg, w,
Tacoma)
Wisconsin (w, Madison):
Hydrology of the Arboretum Marsh (H. L. Young)
Hydrologic effects of dredging small spring ponds (W. J.
Rose)
Hydrology of Cedar Lake (R. S. McLeod)
Hydrology of wetlands (R. P. Novitzki)
Nederlo Creek hydrology (P. A. Kammerer, Jr.)
Wetland hydrology (E. A. Bell)

Heavy metals:

Appalachian region:
Mineral resources, Connecticut-Massachusetts (J. P.
D’Agostino, NC)
South-central (A. A. Stromquist, D)
Hydro- and bio—geochemistry (T. T. Chao, D)
Mineral paragenesis (J. T. Nash, M)
Regional variation in heavy-metals content of Colorado
Plateau stratified rocks (R. A. Cadigan, D)
Rocky Mountain region, fossil beach placers (R. S. Houston,
Laramie, Wyo.)
Solution transport (G. K. Chamanske, M)
Southeastern states, geochemical studies (Henry Bell III,
NC)
States:
Alaska (M):
Gulf of Alaska, nearshore placers (Erk Reimnitz)
Hogatza trend (T. P. Miller)
Southeastern part (D. A. Brew)
Southern Alaska Range (B. L. Reed)
Southwestern part (J. M. Hoare)
Yukon-Tanana Upland (H. L. Foster)
Idaho, Washington Peak quadrangle (D. A. Seeland, D)
Nevada:
Aurora and Bodie districts, Nevada-California (F. J.
Kleinhampl, M)
Basin and Range (D. R. Shawe, D)

Hydraulics, ground water:

Computer analysis—ground-water
Papadopulos, w, NC)

Mechanics of ground-water flow (G. F. Pinder w, NC)

Transient phenomena in ground-water flow (C. E. Mongan,
w, Boston, Mass.)

Transport processes in fluid flows (Akio Ogata, w
Honolulu, Hawaii)

problems (S. S.

1

INVESTIGATIONS IN PROGRESS 339

Hydraulics, surface flow:

Dispersion by turbulent flow in open channels (Nobuhiro
Yotsukura, w, NC)

Effect of temperature on winter runnoff (W. D. Simons, w,
M)

Mechanics of flow structure and fluid resistance—movable
boundry (R. S. McQuivey, W, Bay St. Louis,
Miss.)

Numerical simulation of hydrodynamic phenomena by
digital computer (V. C. Lai, w, NC)

Time-of-travel studies, New York (L. A. Wagner, w, Albany)

Unsteady flow and saline intrusions in rivers and estuaries
(R. A. Baltzer, w, NC)

See also Hydrologic instrumentation.

Hydrologic-data collection and processing:

Data file for well records (R. S. McLeod, w, Madison, Wis.)

Hydrologic probability models (W. H. Kirby, w, NC)

Statistical inferences (E. J. Gilroy, w, NC)

Store-retrieve hydrologic data (D. E. Vaupel, w, Mineola,
N.Y.)

See also Hydrologic instrumentation.

Hydrologic instrumentation:

Analog model unit (E. P. Patten, Jr., w, NC)

Drilling techniques (Eugene Shuter, w, D)

Ground-water network (L. C. Dutcher, w, M)

Hydrologic classification (L. M. Shown, w, D)

Instrumentation and environmental studies (G. E. Ghering,
w, D)

Instrumentation research—“water (H. 0. Wires, w, Bay St.
Louis,'Miss.)

Interagency sedimentation project (J. V. Skinner, w,
Minneapolis, Minn.)

Laboratory research, instruments, water (G. F. Smoot, w,
NC)

Lake and sea ice experiment (W. J. Campbell, w, Tacoma,
Wash.)

Remote sensing quality of water (M. C. Goldberg, w, D)

Satellite data relay project (R. W. Paulson, w, NC)

Satellite data relay support (D. M. Preble, w, Bay St. Louis,
Miss.)

Techniques of flood-plain mapping (G. W. Edelen, Jr., w,
NC)

See also Hydrologic-data collection and processing.

Hydrology, ground-water:

Alluvial fan deposition (W. E. Price, Jr., w, NC)

Aquifer test analysis (J. F. Daniel, w, Tuscaloosa, Ala.)

Borehole geophysics (W. S. Keys, w, D)

Consultation and research (C. V. Theis, w, Albuquerque,
N. Mex.)

Digital modeling ground-water flow (S. P. Larson, w, NC)

Geothermal modeling (J. W. Mercer, w, NC)

Ground-water staff functions (S. W. Lehman, w, D)

Ground-water tracer studies (R. J. Sun, w, NC)

Ground-water type curves (R. W. Stallman, w, D)

Gulf coast hydrodynamics (P. C. Trescott, w, NC)

Hydrologic laboratory (F. S. Riley, w, D)

Hydrology of carbonate rocks (H. E. LeGrand, w, Raleigh,
N.C.)

Hydrology of Wilcox formation with reference to liquid
waste emplacement in the Gulf Coastal Plain
(P. H. Jones, w, Bay St. Louis, Miss.)

Impact of mining on aquifers (N. J. King, w, D)

Hydrology, ground water—Continued

Limestone hydraulic permeability (V. T. Stringfield, w, NC)
Microbes in ground water (G. G. Ehrlich, w, M)
Modeling of geothermal systems (M. L. Sorey, w, M)
Recharge feasibility factors (Jacob Rubin, w, M)
Regional ground-water studies coordination (E. M. Cushing,
w, NC)
Role of confining clays (R. G. Wolff, w, NC)
States:
Alabama, water management, Madison County (W. F.
Harris, Jr., w, Huntsville)
Arizona:
Ground water to Colorado River (0. J. Loeltz, w, Yuma)
Special site studies (H. M. Babcock, w, Tucson)
Water supply, Lake Mead area (R. L. Laney, w,
Phoenix) --
California (w, Laguna Niguel, except as otherwise noted):
Barstow quality-of-water model (S. G. Robson)
Cahuilla Indian Reservation water resources (W. R.
Moyle, Jr.)
Napa County ground water (J. P. Akers, w, M)
Water resources, Upper Coachella (L. A. Swain)
Water resources, Vandenberg AFB (F. W. Giessner)
Florida:
Broward County (H. J. McCoy, w, Miami)
Deep well injection, Ft. Lauderdale (C. B. Sherwood, Jr.,
w, Miami)
Digital model, aquifer system (A. F. Robertson, w,
Tampa) ’
Freshwater in saline aquifers (F. W. Meyer, w, Miami)
Geohydrology, citrus irrigation (W. E. Wilson III, w,

Tampa)

Injecting wastes in saline aquifers (F. W. Meyer, w,
Miami)

Sarasota disposal well, phase 1 (Horace Sutcliffe, Jr., w,
Sarasota)

Storage of storm waters (G. E. Seaburn, w, Tampa)
Water resources, Everglades (A. L. Higer, w, Miami)
Indiana (w, Indianapolis):
Dewatering effects at Bailly +1 (J. R. Marie)
Ground-water cost study (J. R. Marie)
Ground water near Carmel (D. C. Gillies)
Iowa, hydrology of glaciated carbonate terranes (W. L.
Steinhilber, w, Iowa City)
Kansas:
Artificial recharge, west Kansas (J. B. Gillespie, w,
Lawrence) '
Geohydrologic maps, southwest Kansas (E. D. Gutentag,
w, Garden City)
Arbuckle Group, southeastern Kansas (K. M. Keene, w,
Lawrence)
Ford and Hodgeman Counties (E. C. Weakly, w, Garden
City)
Great Bend prairie (S. W. Fader, w, Lawrence)
Greeley and Wichita Counties (S. E. Slagle, w, Garden
City)
Saline water, Little Arkansas Basin (R. B. Leonard, w,
Lawrence)
Scott and Lane Counties (E. D. Gutentag, w, Garden
City)
Water resources, Ness County (E. D. Jenkins, w, Garden

CitY)

340

Hydrology, ground water—Continued
States—Continued
Kentucky (w, Louisville):
Pennyrile Plain potentiometric map (T. W. Lambert)
Water in Elizabethtown area (T. W. Lambert)
Maryland, Maryland Aquifer Studies III (E. G. Otton, w,

Parkville)

Massachusetts, ground water on Cape Cod (M. H. Frimpter,
w, Boston)

Minnesota, recharge fissured rocks (H. O. Reeder, w, St.
Paul)

Missouri, water, southeast Missouri lowlands (E. J. Harvey,
w, Rolla) ‘

Nebraska, test-drilling data collection (C. F. Keech, w,
Lincoln)

Nevada (w, Carson City):
Fort McDermitt ground water (J. R. Harrill)
Pumping effects on Devils Hole (W. W. Dudley, Jr.)
Storage depletion, Las Vegas (J. R. Harrill)
Storage depletion, Pahrump Valley (J. R. Harrill)
New Jersey (w, Trenton):
Digital model, Potomac-Raritan-Magothy (J. E. Luzier)
Geohydrology aquifer system (H. E. Gill)
Geohydrology, east-central New Jersey (G. M. Farlekas)
Mount Laurel-Wenonah Formations (Bronius Nemickas)
Pumpage inventory (William Kam)
New Mexico (w, Albuquerque, except as otherwise noted):
Effects of development in northwest New Mexico (T. E.
Kelly)
Geothermal hydrology, Jemez Mountains (F. W. Trainer)
Lower Rio Grande valley (C. A. Wilson)
Navajo Indian Health Service (W. L. Hiss)
Northern High Plains (E. G. Lappala)
Roswell Basin, quantitative (G. E. Welder, w, Roswell)
Sandia-Manzano Mountains (J. B. Cooper)
Taos and Cerro irrigation (F. C. Koopman)
Water resources, Acoma Reservation (F. P. Lyford)
Water resources, Lagune Reservation (F. P. Lyford)
Water resources, Mimbres Basin (J. S. McLean)
Water resources, Santa Fe (W. A. Mourant)
. Water supply, Tijeras Canyon (J. D. Hudson)
New York, recharge of treated sewage (John Vecchioli, w,
Mineola)
Ohio, Dayton digital model (R. E. Fidler, w, Columbus)
Oklahoma, Ogallala model, Texas County (R. B. Morton, w,
Oklahoma City)
Pennsylvania:
Ground-water flooding, Kingston (D. J. Growitz, w,
Harrisburg)
Hydrogeology, Crawford County (G. R. Schiner, w,
Meadville)
Hydrogeology, Erie County (G. R. Schiner, w, Meadville)
Well data from driller cards (D. W. Speight, w,
Philadelphia)
South Carolina (w, Columbia):
Capacity use study (A. L. Zack)
Low country capacity use study (L. R. Hayes)
South Dakota, basic hydrologic research (E. F. LeRoux, w,
Huron)
Utah (w, Salt Lake City):
Hydrology, Beaver Valley (R. W. Mower)
Navajo Sandstone ground water (R. M. Cordova)

GEOLOGICAL SURVEY RESEARCH 1975

Hydrology, ground water—Continued
States—Continued
Washington (w, Tacoma):
Ground-water hydrology, east-central Washington (A. J.
Hanson, Jr.)
Pullman (H. H. Tanaka)
Wisconsin (w, Madison):
A study of ground—water pollution in the Niagara
dolomite of Door County, Wis. (M. G. Sherrill)
Fish-hatchery water management (R. P. Novitzki)
Ground-water pollution in dolomite aquifer (M. G.
Sherrill)
Shallow aquifer recharge (R. D. Cotter)
Wyoming, Paleozoic hydrology, Powder River Basin (W. G.
Hodson, w, Cheyenne)
Hydrology, surface-water: ,
Atchafalaya River Basin model (M. E. Jennings, w, Bay St.
Louis, Miss.)
Evaluation of low-flow runoff (W. D. Simons, w, M)
Flow in a compound channel (H. J. Tracy, w, Atlanta, Ga.)
Hydrology defined by rainfall simulation (G. C. Lusby, w,
D)
Modeling principles (J. P. Bennett, w, Bay St. Louis, Miss.)
Open channel experiments (F. A. Kilpatrick, w, Bay St.
Louis, Miss.)
Operation models (M. E. Jennings, w, Bay St. Louis, Miss.)
Physical modeling (V. R. Schneider, w, Bay St. Louis, Miss.)
Runoff simulation (P. H. Carrigan, Jr., w, NC)
Water availability, nuclear power (H. C. Riggs, w, NC)
Water quality model development and implementation
(R. A. Baltzer, w, NC)
States:
Alabama, travel-time studies (E. R. German, w, Tuscaloosa)
Alaska, water resources fish sites (G. A. McCoy, w,

Anchorage)
Arizona:
Effects of vegetation changes (H. W. Hjalmarson, w,
Phoenix)

Flood hydrology of Arizona (B. N. Aldridge, w, Tucson)
California:
Flood hydrology, Butte Basin (R. G. Simpson, w,
Sacramento)
Special studies (L. R. Peterson, w, M)
Delaware River Master activity (J. V. B. Wells, w, Milford,

Pa.)

Florida hydrograph simulation studies (J. F. Turner, Jr., w,
Tampa)

Georgia, small area flood hydrology (H. G. Goldeh, w,
Doraville)

Idaho, special studies (C. A. Thomas, w, Boise)
Kansas (w, Lawrence):
Channel geometry (E. R. Hedman)
Flood investigations (H. R. Hejl, Jr.)
Soldier Creek (W. M. Kastner)
Streamflow characteristics (C. V. Burns)
Streamflow models (P. R. Jordan)
Urban runoff, Wichita (D. B. Richards)
Kentucky, small area flood hydrology (R. V. Swisshelm, Jr.,
w, Louisville)
Louisiana (w, Baton Rouge):
Bridge-site computations (B. L. Neely, Jr.)
Characteristics of streams (M. J. Forbes Jr.)

INVESTIGATIONS IN PROGRESS

Hydrology, surface-water.—Continued

States—Continued I

Louisiana—Continued

Small stream flood frequency (L. A. Martens)
Montana (w, Helena):

Bridge—site investigations (M. V. Johnson)

Peak flow, small drainage areas (M. V. Johnson)

New Jersey (w, Trenton):

Low-flow frequency (E. G. Miller)
Tidal stage (A. A. Vickers)

North Carolina, stream system modeling (F. E. Arteaga, w,
Raleigh)

Ohio (w, Columbus):

Flood hydrology, small areas (E. E. Webber)
Hydraulics of bridge sites (R. 1. Mayo)

Low-flow of Ohio streams (R. 1. Mayo)

Time—of-travel studies of Ohio streams (A. O. Westfall)

Oregon, Alsea River basin, effects of logging on streamflow,
sedimentation, and temperature (D. D. Harris, w,
Portland)

South Carolina (w, Columbia):

Data reports, flood forecasting (H. H. Jeffcoat)
Low-flow characteristics (W. M. Bloxham)
South Dakota (w, Huron):
Flood frequency study (L. D. Becker)
Small streams flood frequency (L. D. Becker)
Tennessee (w, Nashville, except as otherwise noted):
Hydrologic effects of strip mining (S. P. Sauer)
Memphis urban flood frequency (C. W. Boning, w,
Memphis)
Metro urban development alternatives (H. C. Wibben)
Small streams modeling (H. C. Wibben)
Tennessee bridge scour (W. J. Randolph)

Texas (w, Austin, except as otherwise noted):

Hydrology of small drainage areas (E. E. Schroeder)

Small watersheds (R. D. Hawkinson)

Trinity River time of travel studies (R. H. Ollman, w,
Fort Worth)

Virginia, urban hydrology, Fairfax County (P. L. Soule, w,
Fairfax)

Washington (w, Tacoma):

Anadromous fish hydraulics (C. H. Swift 111)
Low flow (P. J. Carpenter)

Wisconsin (w, Madison):

Flambeau River digital model (R. S. Grant)
Flood frequency study (D. H. Conger)
Low-flow study (W. A. Gebert)
Water-quality control (W. A. Gebert)

See also Evapotranspiration; Flood investigations; Marine
hydrology; Plant ecology; Urbanization,
hydrologic effects.

Industrial minerals. See specific minerals.
Iron:
Resource studies, United States (Harry Klemic, NC)
Michigan (NC):
Gogebic County, western part (R. G. Schmidt)
Negaunee and Palmer quadrangles (J. E. Gair)
Wisconsin, Black River Falls (Harry Klemic, NC)
Isotope and nuclear studies:

Instrument development (F. J. Jurceka, D)

Interface of isotope hydrology and hydrogeology (I. J.
Winograd, w, NC)

341

Isotope and nuclear studies—Continued
Isotope fractionation (T. B. Coplen II, w, Laguna Niguel,
Calif.)
Isotope ratios in rocks and minerals (Irving Friedman, D)
Isotopes in hydrology (C. T. Rightmire, w, NC)
Isotopic hydrology (F. J. Pearson, w, NC)
Lead isotopes and ore deposits (R. E. Zartman, D)
Mass spectrometry and isotopic measurements (J. S. Stacey,
D)
Nuclear irradiation (G. M. Bunker, D)
Nuclear reactor facility (G. P. Kraker, Jr., w, D)
Radioisotope dilution (L. P. Greenland, NC)
Stable isotopes and ore genesis (R. 0. Rye, D)
Upper mantle studies (Mitsunobu Tatsumoto, D)
See also Geochronological investigations; Geochemistry,
water; Radioactive-waste disposal.
Land resources analysis, Idaho, eastern Snake River Plain
region (S. S. Oriel, D)
Land subsidence:
Geothermal subsidence research (B. E. Lofgren, w,
Sacramento, Calif.)
Land subsidence, Idahome area (E. G. Crosthwaite, w,
Boise, Idaho)
Land subsidence studies (J. F. Poland, w, Sacramento,
Calif.)
Mechanics of aquifer systems (J. F. Poland, w, Sacramento,
Calif.)
Sinkhole studies along public roads (J. G. Newton, w,
Tuscaloosa, Ala.)
Subsidence at Texas City and Seabrook (R. K. Gabrysch, w,
Houston, Tex.)
Land use data and analysis (LUDA) ' program (J. R.
Anderson, 1, NC)
Lead, zinc, and silver:
Lead resources of United States (C. S. Bromfield, D)
Zinc resources of United States (Helmuth Wedow, Jr.,
Knoxville, Tenn.)
States:
Alaska, Southwest Brooks Range (1. L. Tailleur, M)
Arizona, Lochiel and Nogales quadrangles (F. S. Simons, D)
Colorado (D):
San Juan Mountains, eastern, reconnaissance (W. N.
Sharp)
San Juan Mountains, northwestern (F. S. Fisher)
Illinois-Kentucky district, regional structure and ore
controls (D. M. Pinckney, D)
Nevada (M):
Comstock district (D. H. Whitebread)
Silver Peak Range (R. P. Ashley)
Utah, Park City district (C. S. Bromfield, D)
Wisconsin, lead-zinc (W. S. West, Platteville)
Limnology:
Artificial substrates (R. C. Averett, w, M)
Colorado Lakes reconnaissance (D. A. Wentz, w, D)
Hydrology of lakes (G. C. Bortleson, w, Tacoma, Wash.)
Hydrology of lakes in Wisconsin (R. P. Novitzki, w,
Madison, Wis.)
Impoundment water quality (D. R. Williams, w, Harrisburg,
Pa.)
Interrelations of aquatic ecology and water quality (K. V.
Slack, w, M)

342

Limnology—Continued

Limnological study of Maine lakes (D. J. Cowing, w,
Boston, Mass.)
Limnology of selected Ohio lakes (R. L. Tobin, w,
Columbus, Ohio)
Oxygen cycle in streams (R. E. Rathbun, w, Bay St. Louis,
Miss.)
Quality of water:
Lago Carraizo (Ferdinand Quinones-Marquez, w, San
Juan, PR.)
Laguna Tortuguero (Ferdinand Quinones-Marquez, w,
San Juan, PR.)
Lopez Reservoir (R. C. Averett, w, M)
Relation of ground water to lakes (T. C. Winter, w, D)
Stream health, Chester County, Pa. (B. W. Lium, w, West
Chester)
Water quality of impoundments (J. L. Barker, w,
Harrisburg, Pa.)
See also Quality of water.

GEOLOGICAL SURVEY RESEARCH 1975

Marine geology—Continued

States and territories—Con tinued
Alaska—Continued
Beaufort-Chuckchi Sea Continental Shelf (Arthur Grantz)
Beaufort Sea environment sstudies (P. W. Barnes)
Bering Sea (D. W. Scholl)
Bering Sea floor, northern (C. H. Nelson)
Coastal environments (A. T. Ovenshine)
Continental Shelf resources (D. M. Hopkins)
Gulf of Alaska (B. F. Molnia)
Seward Peninsula, nearshore (D. M. Hopkins)
Tectonichistory (R. E. von Huene, NC)
California (M, except as otherwise noted):
I Borderlands, geologic framework (A. E. Roberts)
Borderlands, southern part (A. A. Wagner; G. W. Moore,
La Jolla)
Continental Margin, central part (E. A. Silver)
La J olla marine geology laboratory (G. W. Moore,
La Jolla)

Lunar geology. See Extraterrestrial studies.
Manganese. See Ferro-alloy metals.
Marine geology:

Monterey Bay (H. G. Greene)
San Francisco Bay (D. S. McCulloch)
' San Francisco Bay, geochemistry of sediments (D. H.

Atlantic Continental Shelf:
Environmental impact of petroleum exploration and
production (H. J. Knebel, Woods Hole, Mass.)
Geophysical studies (J. C. Behrendt, Woods Hole, Mass.)
Gulf of Maine section, geologic studies (M. F. Kane,
Woods Hole, Mass.)
Magnetic chronology (E. M. Shoemaker, D. P. Elston,
Flagstaff, Ariz.)
New England coastal zone (R. N. Oldale, Woods Hole,
Mass.)
Resources (R. Q. Foote, NC)
Site surveys (W. P. Dillon, Woods Hole, Mass.)
Stratigraphy (J. C. Hathaway, Woods Hole, Mass.) ,
Stratigraphy and structure (J. S. Schlee, Woods Hole,
Mass.)
Caribbean and Gulf of Mexico:
Coastal environments (H. L. Berryhill, Corpus Christi,
Tex.)
Estuaries (C. W. Holmes, Corpus Christi, Tex.)
Mississippi delta studies (L. E. Garrison, Corpus Christi,
Tex.)
Natural resources and tectonic features (R. G. Martin, Jr.,
Corpus Christi, Tex.)
Oil migration and diagenesis of sediments (C. W. Holmes,
Corpus Christi, Tex.)
Tectonics, Caribbean (J. E. Case, Corpus Christi, Tex.)
Tectonics, gulf (L. E. Garrison, Corpus Christi, Tex.)
Marine mineral resources, worldwide (F. H. Wang, M)
Pacific coast sedimentology (H. E. Clifton, M)
Pacific Ocean, biostratigraphy, deep ocean (J. D. Bukry,
La Jolla, Calif.)
Pacific reef studies (J. I. Tracey, Jr., NC)
Spain, Spanish Continental Margin (Almeria Province) (P. D.
Snavely, Jr., H. G. Greene, H. E. Clifton, W. P.
Dillon, and J. M. Robb, M)
Volcanic geology, Mariana and Caroline Islands (Gilbert
Corwin, NC)
World offshore oil and gas (T. H. McCulloh, Seattle, Wash.)
States and territories:
Alaska (M, except as otherwise noted):
Arctic coastal marine processes (Erk Reimnitz)

Peterson)
Oregon, landsea transect, Newport (P. D. Snavely, Jr., M)
Oregon-California, black sands (H. E. Clifton, M)
Oregon-Washington, nearshore (P. D. Snavely, Jr., M)
Puerto Rico cooperative program (J. V. A. Trumbull,
Santurce)
Texas barrier islands (R. E. Hunter, Corpus Christi)

Marine hydrology:

Hydrologic-oceanographic (F. A. Kohout, w, Woods Hole,
Mass.)

Skylab data applications (A. L. Higer, w, Miami, Fla.)

States and Territories:

Connecticut, Long Island Sound regional study (F. H.
Ruggles, Jr., w, Hartford)

Maryland, effects of water quality changes on biota in
estuaries (R. L. Cory; w, NC)

North Carolina, flow of Chowan River (C. C. Daniel, w,
Raleigh)

Puerto Rico, San Juan lagoons (S. R. Ellis, w, San Juan)

South Carolina, flow and quality of water model (S. J.
Playton, w, Columbia)

See also Hydrology, surface water; Quality of water;
Geochemistry, water; Marine hydrology.

Mercury :

Geochemistry (A. P. Pierce, D)
Mercury deposits and resources (E. H. Bailey, M)
California, Coast Range ultramafic rocks (E. H. Bailey, M)

Meteorites. See Extraterrestrial studies.
Mineral and fuel resources—compilations and topical studies:

Alteration study, Summitville district, Colorado (R. E.
Van Loenen, D) I

Arctic mineral resources investigations (W. P. Brosge, M)

Basin and Range, geologic studies (F. G. Poole, D)

Colorado Plateau (R. P. Fischer, D)

Information bank, computerized (J. A. Calkins, NC)

Iron resources studies, United States (Harry Klemic, NC)

Lightweight-aggregate resources, United States (A. L. Bush,
D)

Metallogenic maps, United States (P. W. Guild, NC)

Metals in volcaniclastic rocks (D. A. Lindsey, D)

Mineral deposit controls, ce'ntral states (A. V. Heyl, Jr., D)

INVESTIGATIONS IN PROGRESS 343

Mineral and fuel resources—compilations and topical studies—

Continued
Mineral-resources map, Utah (L. S. Hilpert, Salt Lake City)
Mineral-resources surveys:
Northern Wisconsin (C. E. Dutton, Madison)
Primitive and Wilderness Areas:

Alpine-Enchantment Lakes study area, Wash. (J. L.
Gualtieri, Spokane)

Beartooth-Absaroka addition study area, Mont. (J. E.
Elliott, D)

Bob Marshall Wilderness Area, Montana (R. L. Earhart,
D)

Boulder-Pioneer study area, Idaho (F. S. Simons, D)

Bradwell Bay Wilderness and Sopchoppy River study
area, Florida (C. C. Cameron, NC)

Cabinet Mountains Wilderness Area, Mont. (J. D. Wells,
D)

Cougar Lakes-Mt. Aix study area, Wash. (G. C.
Simmons, D)

Galiuro Wilderness Area, Ariz. (S. C. Creasey, M)

Granite Fiords Wilderness Area, Alaska (George Gryc,
M)

Hells Canyon, Oregon-Idaho (G. C. Simmons, D)

Indian Peaks Area, Colo. (R. C. Pearson, D)

Jarbidge Wilderness Area, Nev. (R. R. Coats, M)

Laramie Peaks study area, Wyo. (Kenneth Segerstrom,
D)

Maroon Bells-Snowmass Wilderness Area, Colorado
(V. L. Freeman, D)

Mount Zirkel Wilderness Area, Colo. (G. L. Snyder, D)

North Absaroka Wilderness Area, Wyo. (W. H. Nelson, ,

M)
Pioneer Mountains study area, Idaho (F. S. Simons, D)
Sawtooth Recreation Area, Idaho (C. M. Tschanz, D)
South Warner Wilderness Area, Calif. (W. A. Duffield,
M)
Teton study area, Wyo. (J. D. Love, D)
Teton Wilderness Area, Wyoming (J. C. Antweiler, D)
Tracy Arms-Fords Terror study area, Alaska (D. A.
Brew, M)
Trinity Alps Primitive Area, Calif. (P. Holz, M)
West Elk Wilderness Area, Colo. (D. L. Gaskill, D)
White Mountain Wilderness Area, N. Mex. (Kenneth
Segerstrom, D)
Puerto Rico (D. P. Cox, Santurce)
Southeastern United States (R. A. Laurence, Knoxville,
Tenn.)
Nonmetallic deposits, mineralogy (B. M. Madsen, M)
Peat resources, Northeastern States (C. C. Cameron, NC)
Wilderness Program:
Geochemical services (D. J. Grimes, D)
Geophysical services (M. F. Kane, D)
States:
Alaska (M, except as otherwise noted):
Geology (George Gryc)
Southwestern Brooks Range (I. L. Tailleur)
Michigan, base and precious metals in Archean greenstones
(W. C. Prinz, NC)
Pennsylvania, Greater Pittsburgh region clay and shale,
limestone (B. J. O’Neill, Jr., Carnegie)
Nevada, igneous rocks and related ore deposits (M. L.
Silberman, M)-

Mineral and fuel resources-compilations and topical studies-
Continued
States—Continued
Texas, mineral resource appraisal, Van Horn-El Paso area
(T. E. Mullens, D)
See also specific minerals or fuels.
Mineralogy and crystallography, experimental:
Crystal chemistry (Malcolm Ross, NC)
Crystal structure, sulfides (H. T. Evans, Jr., NC)
Diagenesis of feldspars (R. W. Luce, M)
Electrochemistry of minerals (Motoaki Sato, NC)
MineralOgic services and research (M. L. Smith, NC; A. J.
Gude, D)
Mineralogy of heavy metals (F. A. Hildebrand, D)
Planetary mineralogical studies (Priestley Toulmin III, NC)
Rapid mineral analysis (L. G. Schultz, D)
Research on ore minerals (B. F. Leonard, D)
See also Geochemistry, experimental.
Minor elements:
Geochemistry (George Phair, NC)
Niobium:
Colorado, Wet Mountains (R. L. Parker, D)
Niobium and tantalum, distribution in igneous rocks
(David Gottfried, NC)
Phosphoria Formation, stratigraphy and resources (R. A.
Gulbrandsen, M)
Nonpegmatite lithium resources (J. D. Vine, D)
Rare-earth elements, resources and geochemistry (J. W.
Adams, D)
Trace-analysis methods, research (F. N. Ward, D)
Model studies, geologic and geophysical:
Computer modeling of rock-water interactions (J. L.

Haas, Jr., NC)
Computer modeling, tectonic deformation (J. H. Dieterich,
M)
Model studies, hydrologic. See Water resources; Hydrologic
instrumentation.

Molybdenum. See Ferro-alloy metals.
Moon studies. See Extraterrestrial studies.
Nickel. See Ferro-alloy metals.
Nuclear explosions, geology:
Applied geophysics, Nevada Test Site (G. D. Bath, D)
Engineering geophysics, Nevada Test Site (R. D. Carroll, D)
Geologic effects of nuclear explosions (F. A. McKeown, D)
Geologic investigations:
Amchitka Island, Alaska (L. M. Gard, Jr., D)
Nevada Test Site (P. P. Orkild, D)
Geomechanical investigations, Nevada Test Site (J. R. Ege,
D)
Peaceful uses of nuclear explosions (F. W. Stead, D)
Nuclear explosions, hydrology:
Hydrologic studies of small nuclear test sites (G. A.
Dinwiddie, w, D)
Hydrology in nuclear-explosive underground engineering
(J. E. Weir, Jr., w, D)
Hydrology of Amchitka Island Test Site, Alaska (W. C.
Ballance, w, D)
Hydrology of Central Nevada Test Site (G. A. Dinwiddie, w,
D)
Hydrology of Nevada Test Site (W. W. Dudley, Jr., w, D)
Oil shale:
Organic geochemistry (R. E. Miller, D)

344

Oil shale—Continued
Oil shale and associated minerals (J. L. Renner, c, D)
Petrology (J. R. Dyni, D)
States:
Alaska, Anatuvuk Pass (R. B. Sanders, c, Anchorage)
Colorado (D, except as otherwise noted):
East-central Piceance Creek basin (R. B. O’Sullivan)
Lower Yellow Creek area (W. J. Hail)
Piceance Creek basin (J. R. Donnell)
State resources (D. C. Duncan, NC)
Utah (W. B. Cashion, Jr., D)
Wyoming-Colorado, Eocene rocks (H. W. Roehler, D)
Paleobotany, systematic:
Diatom studies (G. W. Andrews, NC)
Floras:
Cenozoic, Pacific Northwest (J. A. Wolfe, M)
Cenozoic, Western United States and Alaska (J. A. Wolfe,
M)
Devonian (J. M. Schopf, Columbus, Ohio)
Paleozoic (S. H. Mamay, NC)
Fossil wood and general paleobotany (R. A. Scott, D)
Plant microfossils:
Cenozoic (E. B. Leopold, D)
Mesozoic (R. H. Tschudy, D)
Paleozoic (R. M. Kosanke, D)
Paleoecology :
Faunas, Late Pleistocene, Pacific coast (W. O. Addicott, M)
Foraminif era :
Cenozoic, larger forms (K. N. Sachs, Jr., NC)
Ecology (M. R. Todd, NC)
Recent, eastern Pacific (P. J. Smith, M)
Ostracodes, Recent, North Atlantic (J. E. Hazel, NC)
Paleoenvironment studies, Miocene, Atlantic Coastal Plain
(T. G. Gibson, NC)
Pollen, Recent distribution studies (E. B. Leopold, D)
Te mpskya, Southwestern United States (C. B. Read,
Albuquerque, N. Mex.)
Vertebrate faunas, Ryukyu Islands, biogeography (F. C.
Whitmore, Jr., NC)
Paleontology, invertebrate, systematic:
Brachiopods:
Carboniferous (Mackenzie Gordon, Jr., NC)
Ordovician (R. B. Neuman, NC; R. J. Ross, Jr., D)
Permian (R. E. Grant, NC)
Upper Paleozoic (J. T. Dutro, Jr., NC)
Bryozoans:
Ordovician (O. L. Karklins, NC)
Cephalopods:
Cretaceous (D. L. Jones, M)
Jurassic (R. W. Imlay, NC)
Upper Cretaceous (W. A. Cobban, D)
Upper Paleozoic (Mackenzie Gordon, Jr., NC)
Chitinozoans, Lower Paleozoic (J. M. Schopf, Columbus,
Ohio)
Conodonts:
Devonian and Mississippian (C. A. Sandberg, D)
Paleozoic (J. W. Huddle, NC)
Corals, rugose:
Mississippian (W. J. Sando, NC)
Silurian-Devonian (W. A. Oliver, Jr., NC)
Foraminif era :
Fusuline and orbitoline (R. C. Douglass, NC)

GEOLOGICAL SURVEY RESEARCH 1975

Paleontology, invertebrate, systematic—Continued
Foraminifera—Continued
Cenozoic (M. R. Todd, NC)
Cenozoic, California and Alaska (P. J. Smith, M)
Mississippian (B. A. Skipp, D)
Recent, Atlantic shelf (T. G. Gibson, NC)
Tertiary, larger (K. N. Sachs, Jr., NC)
Gastropods:
Mesozoic (N. F. Sohl, NC)
Miocene-Pliocene, Atlantic coast (T. G. Gibson, NC)
Paleozoic (E. L. Yochelson, NC)
Graptolites, Ordovician-Silurian (R. J. Ross, Jr., D)
Mollusks, Cenozoic, Pacific coast (W. A. Addicott, M)
Ostracodes:
Lower Paleozoic (J. M. Berdan, NC)
Upper Cretaceous and Tertiary (J. E. Hazel, NC)
Upper Paleozoic (I. G. Sohn, NC)
Pelecypods:
Inoceramids (D. L. Jones, M)
Jurassic (R. W. Imlay, NC)
Paleozoic (John Pojeta, Jr., NC)
Triassic (N. J. Silberling, M)
Radiolaria (K. N. Sachs, Jr., NC)
Trilobites, Ordovician (R. J. Ross, Jr., D)
Paleontology, stratigraphic:
Cenozoic:
Coastal plains, Atlantic and Gulf (Druid Wilson, NC)
Diatoms, Great Plains, nonmarine (G. W. Andrews, NC)
Foraminifera, smaller, Pacific Ocean and islands (M. R.
Todd, NC)
Mollusks:
Atlantic coast, Miocene (T. G. Gibson, NC)
Pacific coast, Miocene (W. O. Addicott, M)
Pollen and spores, Kentucky (R. H. Tschudy, D)
Vertebrates:
Pleistocene (G. E. Lewis, D)
Atlantic coast (F. C. Whitmore, Jr., NC)
Pacific coast (C. A. Repenning, M)
Panama Canal Zone (F. C. Whitmore, Jr., NC)
Mesozoic:
Pacific coast and‘Alaska (D. L. Jones, M)
Cretaceous:
Alaska (D. L. Jones, M)
Foraminifera:
Alaska (H. R. Bergquist, NC)
Atlantic and Gulf Coastal Plains (H. R. Bergquist,
NC)
Pacific coast (R. L. Pierce, M)
Gulf coast and Caribbean (N. F. Sohl, NC)
Molluscan faunas, Caribbean (N. F. Sohl, NC)
Western interior United States (W. A. Cobban, D)
Jurassic, North America (R. W. Imlay, NC)
Triassic, marine faunas and stratigraphy (N. J. Silberling,
M)
Paleozoic:
Devonian and Mississippian conodonts, Western United
States (C. A. Sandberg, D)
Fusuline Foraminifera, Nevada (R. C. Douglass, NC)
Mississippian biostratigraphy, Alaska (A. K. Armstrong,
M)
Onesquethaw Stage (Devonian), stratigraphy and rugose
corals (W. A. Oliver, NC)

INVESTIGATIONS IN PROGRESS

Paleontology, stratigraphic—Continued
Paleozoic—Continued
Paleobotany and coal studies, Antarctica (J. M. Schopf,
Columbus, Ohio)
Palynology of cores from Naval Petroleum Reserve No. 4
(R. A. Scott, D)
Subsurface rocks, Florida (J. M. Berdan, NC)
Ordovician :
Bryozoans, Kentucky (0. L. Karklins, NC)
Stratigraphy and brachiopods, Eastern United States
(R. B. Neuman, NC)
Western United States (R. J. Ross, Jr., D)
Silurian-Devonian :
Corals, northeast United States (W. A. Oliver, Jr., NC)
Upper Silurian-Lower Devonian, Eastern United States
(J. M. Berdan, NC)
Mississippian :
Stratigraphy and brachiopods, northern Rocky
Mountains and Alaska (J. T. Dutro, Jr., NC)
Stratigraphy and corals, northern Rocky Mountains
(W. J. Sando, NC)
Pennsylvanian :
Fusulinidae:
Alaska (R. C. Douglass, NC)
North-central Texas (D. A. Myers, D)
Spores and pollen, Kentucky (R. M. Kosanke, D)
Permian:
Floras, Southwestern United States (S. H. Mamay, NC)
Stratigraphy and brachiopods:
Alaska (R. E. Grant, NC)
Southwestern United States (R. E. Grant, NC)
Upper Paleozoic, Western States (Mackenzie Gordon,’ Jr.,
NC)
Paleontology , vertebrate, systematic:
Artiodactyls, primitive (F. C. Whitmore, Jr., NC)
Pinnipedia (C. A. Repenning, M)
Pleistocene fauna, Big Bone Lick, Ky. (F. C. Whitmore, Jr.,
NC)
Tritylodonts, American (G. E. Lewis, D)
Paleotectonic maps. See Regional studies and compilations.
Petroleum and natural gas:
Oil and gas map, North America (W. W. Mallory, D)
Organic geochemistry (J. G. Palacas, D)
Source rocks of Permian age in Utah, Idaho, Wyoming, and
Montana (E. K. Maughan, D)
Western United States:
Devonian and Mississippian (C. A. Sandberg, D)
Devonian and Mississippian flysch source-rock studies
(F. G. Poole, D)
Properties of reservoir rocks (R. F. Mast, D)
Williston basin, Wyoming, Montana, North Dakota, South
Dakota (C. A. Sandberg, D)
World, petroleum-resource evaluation (A. B. Coury, D)
States:
Alaska (M):
Cook Inlet (L. B. Magoon III)
North Slope, petroleum geology (R. D. Carter)
California (M, except as otherwise noted):
Eastern Los Angeles basin (T. H. McCulloh, Seattle,
Wash.)
Salinas Valley (D. L. Durham)

345

Petroleum and natural gas—Continued
States—Continued
California—Continued
Southern San Joaquin Valley, subsurface geology (J. C.
Maher)
Colorado:
Citadel Plateau (G. A. Izett, c, D)
'Denver Basin, Tertiary coal zone and associated strata
(P. A. Soister, c, D)
Grand Junction 2-degree quadrangle (W. B. Cashion, D)
Savery quadrangle (C. S. V. Barclay, c, D)
Montana:
Bearpaw Mountains area (B. C. Hearn, Jr., NC)
Decker quadrangle (B. E. Law, c, Casper, Wyo.)
New Mexico, San Juan basin (E. R. Landis, D)
North Dakota, White Butte 15-minute quadrangle (K. S.
Soward, c, Casper)
Pennsylvania, Greater Pittsburgh region oil and gas fields
(W. S. Lytle, Carnegie)
Utah:
Canaan Peak quadrangle (W. E. Bowers, c, D)
Collet Top quadrangle (H. D. Zeller, c, D)
Grand Junction 2-degree quadrangle (W. B. Cashion, D)
Upper Valley quadrangle (W. E. Bowers, c, D)
Wyoming:
Browns Hill quadrangle (C. S. V. Barclay, c, D)
Lander area phosphate reserve (W. L. Rohrer, c, D)
Oil Mountain quadrangle (W. H. Laraway, c, Casper)
Poison Spider quadrangle (W. H. Laraway, c, Casper)
Reid Canyon quadrangle (W. H. Laraway, c, Casper)
Savery quadrangle (C. S. V. Barclay, c, D)
Square Top Butte quadrangle (W. H. Laraway, c, Casper)
Stratigraphy, Frontier Formation, northeastern Wyoming
(E. A. Merewether, D)
Petrology. See Geochemistry and petrology, field studies.
Phosphate:
Phosphoria Formation, stratigraphy and resources (R. A.
Gulbrandsen, M)
Southeastern United States, phosphate resources (J. B.
Cathcart, D)
States:
Alaska, Anatuvuk Pass (R. B. Sanders, c, Anchorage)
Florida, land-pebble phosphate deposits (J. B. Cathcart, D)
Idaho (c, Salt Lake City, Utah, except as otherwise noted):
Alpine quadrangle (H. F. Albee)
Palisades Dam quadrangle (D. A. Jobin, c, D)
Poker Peak quadrangle (H. F. Albee)
Montana, Melrose phosphate field (G. D. Fraser, c, D)
Nevada, Spruce Mountain 4 quadrangle (G. D. Fraser, c, D)
Utah:
Crawford Mountains (W. C. Gere, c, M)
Ogden 4 NW quadrangle (R. J. Hite, c, D)
Wyoming:
Alpine quadrangle (H. F. Albee, c, Salt Lake City,
Utah)
Bull Creek quadrangle (M. L. Schroeder, c, D)
Camp Davis quadrangle (M. L. Schroeder, c, D)
Crawford Mountains phosphate deposits (W. C. Gere, c,
M)
Pickle Pass quadrangle (D. A. Jobin, c, D)
Pine Creek quadrangle (D. A. Jobin, c, D)

346

Plant ecology:

Basic research in vegetation and hydrology (R. S. Sigafoos,
w, NC)

Hydrology and pinyon-juniper (R. J. Owen, w, D)

Periodic plant-growth phenomena and hydrology (R. L.
Phipps, w, NC)

Transport processes (C. F. N ordin, w, D)

Vegetation changes in southwestern North America (R. M.
Turner, w, Tucson, Ariz.)

See also Evapotranspiration; Geochronological investi-
gations; Limnology.

Platinum:

Mineralogy and occurrence (G. A. Desborough, D)
Montana, Stillwater complex (N. J Page, M)
Wyoming, Medicine Bow Mountains (M. E. McCallum, Fort
Collins, Colo.)
Potash:
Colorado and Utah, Paradox basin (0. B. Raup, D)
New Mexico:
Carlsbad, potash and other saline deposits (C. L. Jones,
M)
Southeastern, distribution map of potash deposits (P. C.
Aguilar, E. T. Sandell, c, Roswell)

Primitive areas. See under Mineral and fuel resources—
co mpilations and topical studies,
mineral-resources surveys.

Public and industrial water supplies. See Quality of water;
Water resources.

Quality of water:

Development of biological methods (B. W. Lium, w,
Atlanta, Ga.)
Geochemistry, western coal region (G. L. Feder, w, D)
Heat transfer (H. E. Jobson, w, Bay St. Louis, Miss.)
Identification of organics in water (M. C. Goldberg, w, D)
Modeling (D. B. Grove, w, D)
Organics in oil shale residues (J. A. Leenheer, w, D)
Pesticide monitoring network (R. J. Pickering, w, NC)
Pesticide pollutants (R. L. Wershaw, w, D)
Radioanalytical methods (L. L. Thatcher, w, D)
Radiochemical network (R. J. Pickering, w, NC)
Stream temperature patterns (E. J. Pluhowski, w, NC)
Surface-water-quality modeling (S. M. Zand-Yazdani, w, M)
Thermal pollution (G. E. Harbeck, Jr., w, D)
Trace element availability in sediments (E. A. Jenne, w, M)
Transport in ground water (L. F. Konikow, w, D)
States:
Alabama (w, Tuscaloosa):
Water problems in coal-mine areas (A. L. Knight)
Water quality of Alabama streams (E. R. German)
Water resources in oil fields (W. J. Powell)
Alaska, quality-of-water analyses (R. L. Madison, w,
Anchorage)
Arkansas, waste-assimilation capacity (C. T. Bryant, w,
Little Rock)

California:
Ground-water quality, Barstow (J. L. Hughes, w, Laguna
Niguel)
Hydrology, Sagehen Creek (R. G. Simpson, w,
Sacramento)

Quality of water, California streams (G. A. Irwin, w, M)
Santa Maria water quality (J. L. Hughes, w, Laguna Niguel)

GEOLOGICAL SURVEY RESEARCH 1975

Quality of water—Continued
States—Continued
Colorado (w, D): ,
Effects of feedlots on ground water (S. G. Robson)
Effects of sludge on ground water (S. G. Robson)
Florida:
Coastal quality of water modeling (D. A. Goolsby, w,
Tallahassee)
Contaminants, Broward County (C. B. Sherwood, w,
Miami)
Deep-well waste injection (C. A. Pascale, w, Ocala)
Florida barge canal water quality (A. G. Lamonds, Jr., w,

Winter Park) ,.
Injection wells, Santa Rosa County (C. A. Pascale, w,
Tallahassee)
Lakes Faith, Hope, and Charity (A. G. Lamonds, Jr., w,
Winter Park)

Loxahatchee River Basin model (H. G. Rodis, w, Miami)

Nutrient uptake study (B. F. McPherson, w, Miami)

Storm water quality, south Florida (H. C. Mattraw, Jr.,
w, Miami)

Subsurface waste storage (G. L. Faulkner, w, Tallahassee)

Water quality, Broward County (C. B. Sherwood, w,

Miami)
Water quality, South New River Channel (T. N. Russo, w,
Miami)
Hawaii, ground-water monitoring network (D. A. Davis, w,
Honolulu)

Illinois, quality-of-water monitoring, Fulton County (C. R.
Sieber, w, Champaign)
Indiana (w, Indianapolis):
Landfill monitoring, Marion County (R. A. Pettijohn)
Stream temperature study (W. J. Shampine)
Watershed water quality (M. A. Ayers)
Kansas (w, Lawrence):
South Fork, Ninnescah River basin (A. M. Diaz)
Western Kansas (J. S. Rosenhein, L. R. Hathaway)
Kentucky (w, Louisville):
Effects of coal mining, Kentucky River (K. L. Dyer)
Subsurface waste disposal (R. W. Davis)
Louisiana (w, Baton Rouge):
Pollution capacity of streams (D. E. Everett)
Water quality, Atchafalaya Basin (F. C. Wells)
Minnesota, watershed water-quality appraisal (M. R. Have,
w, St. Paul)
Nebraska, ground-water quality (R. A. Engberg, w, Lincoln)
Nevada (w, Carson City):
Ground-water contamination, Hawthorne (F. E. Rush)
Ground-water contamination by explosives wastes (A. S.
Van Denburgh)
New Jersey (w, Trenton):
Channel geometry—New Jersey streams (M. C. Yurewicz)
Waste-water reclamation (William Kam)
New Mexico, Malaga Bend evaluation (C. C. Cranston, w,
Carlsbad)
New York (w, Albany, except as otherwise noted):
Biology of landfill leaching (T. A. Ehlke)
Public water supply, New York State (G. E. Williams)
Solid-waste sites, Suffolk (G. E. Kimmel, W, Mineola)
Pennsylvania (w, Harrisburg):
Anthracite mine discharge (D. J. Growitz)

INVESTIGATIONS IN PROGRESS

Quality of water—Continued
States—Continued
Pennsylvania—Continued
Ground-water quality in Pennsylvania (C. W. Poth)
Lakes, eastern Pennsylvania (J. L. Barker)
Water quality in Tioga River basin (J. R. Ritter)
South Carolina (w, Columbia):
Quality, Cooper River rediversion (K. F. Harris)
Savannah River plant (D. I. Cahal)
Texas, Colorado River salinity (Jack Rawson, w, Austin)
Virginia, quality of ground waters (S. M. Rogers, w,
Richmond)
Washington, waste effects, coastal waters (W. L. Haushild,
w, Tacoma)
Wisconsin (w, Madison):
Irrigation and ground-water quality (S. M. Hindall)
Nederlo Creek biota (P. A. Kammerer, Jr.)
Str‘eam reaeration (R. S. Grant)
,Waste assimilation in streams (R. S. Grant)
also Geochemistry; Hydrologic instrumentation;
Hydrology , surface water; Limnology;
Marine hydrology; Sedimentology; Water
resources.
Quicksilver. See Mercury.
Radioactive materials, transport in water. See Geochemistry,
water.
Radioactive-waste disposal:
Digital model, waste transport (J. B. Robertson, w, Idaho
Falls, Idaho)
Hydraulic fracturing (R. J. Sun, w, NC)
Hydrology of nuclear landfill (A. D. Randall, w, Albany,
N.Y.) ‘
Hydrology of subsurface waste disposal, National Reactor
Testing Station, Idaho (J. T. Barraclough, w,
Idaho Falls)
Maxey Flats investigation, Kentucky (H. H. Zehner, w,
Louisville)
Radioactive waste burial (George DeBuchananne, w, NC)
Radioactive waste burial study (J. M. Cahill, w, Columbia,
SC.)
Radiohydrology technical coordination
Buchananne, w, NC)
Solid radioactive waste burial sites,
Webster)
solid-waste disposal, Los Alamos, N. Mex. (T. E. Kelly, w,
Albuquerque)
Waste disposal sites (S. S. Papadopulos, w, NC)
Waste emplacement: 1
Preliminary overview (Harley Barnes, D)
Southeast New Mexico '(A. L. Brokaw, D)
See also Geochemistry, water.
Rare-earth metals. See Minor elements.
Regional studies and compilations, large areas of the United
States:
Basement rock map (R. W. Bayley, M)
Paleotectonic-map folios: .
Devonian System (E. G. Sable, D)
Mississippian System (L. C. Craig, D)
Pennsylvanian System (E. D. McKee, D)
Remote sensing:
Geologic applications:
Airborne and satellite research:
Aeromagnetic studies (M. F. Kane, D)

See

(George

Tennessee (D. A.

De-

347

Remote sensing—Continued
Geologic applications—Continued
Airborne and satellite research—Continued
Application of LAN DSAT imagery to worldwide
disaster monitoring (C. J. Robinove, 1, NC)
Development of an automatic analog earthquake
processor (J. P. Eaton-,4 M)
Electromagnetic research (F. C. Frischknecht, D)
Fraunhofer line discriminator studies (R. D. Watson,
D)
Gamma radioactivity studies (J. A. Pitkin, D)
Geochemical plant stress (F. C. Canney, D)
Geothermal resources (Kenneth Watson, D)
Infrared surveillance of volcanoes (J. D. Friedman, D)
Interpretation studies (R. H. Henderson, NC)
LANDSAT and Skylab data for evaluation of faults
and earthquake hazards (E. H. Lathram, P. M.
Merifield, M)
Linear features of the conterminous U.S. (W. D.
Carter, 1, NC)
National aeromagnetic survey (J. R. Henderson, D)
Regional studies (Isidore Zietz, NC)
Remote sensing geophysics (Kenneth Watson, D)
Satellite magnetometry (R. D. Regan, NC)
Surficial and thematic mapping (T. N. V. Karlstrom,
Flagstaff, Ariz.)
Terrain mapping from Skylab data (H. W. Smedes, D)
Urban geologic studies (T. W. Offield, D)
Volcanic gas monitoring (Motoaki Sato, NC)
Application of LANDSAT data to resources inventories
of small impoundments (G. A. Thorley, J. B.
Reynolds, 1, NC)
Comparison of land use, hydrology, and land form
analysis made from LANDSAT imagery and from
aerial orthophotographs (G. A. Thorley, A. M.
W011, 1, NC)
LAN DSAT data for surface-water estimates (Morris
Deutsch, D. G. Moore, 1, NC)
LANDSAT-1 experiments:
Analysis of multispectral data, Pakistan (R. G.
Schmidt, NC)
CARETS—A prototype regional environmental
information system (R. H. Alexander, 1, NC)
Census cities experiment in urban-change detection
(J. R. Wray, 1, NC)
Computer mapping of terrain using multispectral data,
Yellowstone National Park (H. W. Smedes, D)
Effects of the atmosphere on multispectral mapping of
rock type by computer, Cripple Creek-Canon
City, Colo. (H. W. Smedes, D)
Evaluation of Great Plains area (R. B. Morrison, D)
Evaluation of Iranian playas, potential locations for
economic and engineering development (D. B.
Krinsley, NC)
Geologic mapping, South America (W. D. Carter, 1,
NC)
Identification of geostructures,
evaluation (George Gryc, M)
Investigations of the Basin and Range-Colorado Plateau
boundary, Arizona (D. P. Elston, Ivo Lucchitta,
Flagstaff)
Iron-absorption band analysis for the discrimination of
iron-rich zones (L. C. Rowan, NC)

mineral resource

348 GEOLOGICAL SURVEY RESEARCH 1975

Remote sensing—Continued
Hydrologic applications:

Remote sensing—Continued
Geologic applications—Continued

LAN DSAT-l experiments—Continued

Land-use mapping and modeling for the Phoenix
quadrangle (J. L. Place, 1, NC)

Monitoring changing geologic features, Texas Gulf
Coast (R. B. Hunter, Corpus Christi, Tex.)

Morphology, provenance, and movement of desert
sand seas in Africa, Asia, and Australia (E. D.
McKee, D)

North-central Arizona Test Site (D. P. Elston,
Flagstaff)

Post-1890 A.D. episode erosion, Arizona Regional
Ecological Test Site (R. B. Morrison, D)

Prototype volcano surveillance network (J. P. Eaton,
M)

Remote sensing of permafrost and geologic hazards in
Alaska (0. J. Fer‘rians, Jr., M)

Structural, volcanic, glaciologic, and vegetation
mapping, Iceland (R. S. Williams, Jr., 1, NC)

Studies of the inner shelf and coastal sedimentation
environment of the Beaufort Sea (E. Reimnitz,
M)

Study of multispectral imagery, Northwestern Saudi
Arabia (A. J. Bodenlos, NC)

Suspended particulate matter in nearshore surface
waters, Northeast Pacific Ocean and the Hawaiian
Islands (P. R. Carlson, M)

Thermal surveillance of active volcanoes (J. D.
Friedman, NC)

LAN DSAT-2 experiments, mineral resource inventory
and exploration, Andes Mountains (W. D. Carter,
1, NC)

LANDSAT imagery and DOS to relate water depth to
observed area of inundation of coastal marshes
(G. A. Thorley, W. Herke, 1, NC)

Monitoring weather parameters for the High Plains
Cooperative Program with LANDSAT DCS (G. A.
Thorley, A. M. Kahn, 1, NC)

Northern Great Plains wetlands from LANDSAT data
(Morris Deutsch, G. Moore, 1, NC)

Skylab/EREP studies:

Effects of the atmosphere on multispectral mapping of
rock type by computer, Cripple Creek-Canon
City, Colo. (H. W. Smedes, D)

Evaluation of Great Plains area (R. B. Morrison, D)

Marine and coastal processes on the Puerto Rico-Virgin
Islands Platform (J. V. A. Trumbull, Corpus
Christi, Tex.)

Multispectral mapping of terrain by computer,
Yellowstone National Park (H. W. Smedes, D)
Post-1890 A.D. episode erosion, Arizona Regional

Ecological Test Site (R. B. Morrison, D)

Remote sensing geophysics (Kenneth Watson, D)

Urban and regional land-use analysis—CARETS and
census cities experiment (R. H. Alexander, 1, NC)

Skylab/visual observations:

Desert sand seas (E. D. McKee, D; C. S. Breed,
Flagstaff, Ariz.)

Volcanologic features (J. D. Friedman, D)

Time-lapse satellite data for monitoring dynamic
hydrologic phenomena (Morris Deutsch, S.
Serebreny, 1, NC)

Application of aerial-measurement techniques (M. L.
Brown, w, Prescott, Ariz.)

Arctic Ice Dynamics Joint Experiment (H. E. Skibitzke,
w, Prescott, Ariz.)

Arizona Test Site (H. H. Schumann, w, Phoenix)

Basin precipitation from satellite data (Morris Deutsch,
P. A. Davis, 1, NC)

Delaware River basin LANDSAT project (R. W. Paulson,
w, Harrisburg, Pa.)

Delineation of shallow glacial drift aquifers in eastern
South Dakota (Morris Deutsch, P. Rahn, 1, NC)

Development of aerial-measurement techniques (H. E.
Skibitzke, Prescott, Ariz.)

Detection of oil on marine waters using LANDSAT data
(Morris Deutsch, 1, NC)

Image-map atlas of the Lake Ontario basin (Morris
Deutsch, A. Falconer, 1, NC)

LAN DSAT snowcover mapping (M. F. Meier, w, Tacoma,
Wash.)

LANDSAT—South Florida (A. L. Higer, w, Miami,
Fla.)

LANDSAT data for ground-water exploration (Morris
Deutsch, 1, NC)

Measurement of areal and temporal differences in
surface-water conditions in migratory bird habitat
(G. A. Thorley, D. S. Gilmer, 1, NC)

Microwave remote sensing (G. K. Moore, w, Bay St.
Louis, Miss.)

Monitoring center pivot irrigation, Holt County,
Nebraska (W. R. Hemphill, 1, NC)

Optical enhancement of LANDSAT imagery for
hydrogeological appraisal, north Yemen (Morris
Deutsch, 1, NC)

Polar-ice remote sensing (W. J. Campbell, w, Tacoma,
Wash.)

Remote sensing of Elephant Butte-Fort Quitman Project
(G. A. Thorley, D. Mach, 1, NC)

Remote-sensing techniques (E. J. Pluhowski, w, NC)

Remote sensing, wetlands (V. P. Carter, w, NC)

Snowpack measurements by radar (M. F. Meier, w
Tacoma, Wash.)

Usefulness of remote sensing imagery to the Wild and
Scenic Rivers Act (G. A. Thorley, R. N. Colwell,
1, NC)

States:

Alabama, remote-sensing data collection (J. G. Newton,
w, Tuscaloosa)

Arizona, snowcover mapping (H. H. Schumann, w,
Phoenix)

Connecticut, Connecticut River estuary (F. H.
Ruggles, Jr., w, Hartford)

Minnesota, remote sensing for water management (G. F.
Lindholm, w, St. Paul)

South Carolina, sediment sources and loading (S. J.
Playton, w, Columbia)

Land resources applications:

Applications of LANDSAT imagery to land systems
mapping, Australia (C. J. Robinove, 1, NC)
Colorado River natural resources and land—use data
acquisition (G. A. Thorley, R. L. Hansen, 1,

NC)

a

INVESTIGATIONS IN PROGRESS

Remote sensing—Continued
Hydrologic applications—Continued

Investigation of remote sensing techniques to assess
agricultural drainage (G. A. Thorley, W. A.
Lidester, I, NC)

LANDSAT imagery for aiding objectives of the IFYGL
(Morris Deutsch, A. Falconer, 1, NC)

LAN DSAT imagery for archaeological resource inventory
and management potential in Chaco Canyon
National Monument, New Mexico (G. A. Thorley,
T. R. Lyons, 1, NC)

LAN DSAT imagery for range condition (Morris Deutsch,
E. L. Maxwell, 1, NC)

Model to project land uses and encroachment patterns,
Denver area (G. A. Thorley, L. D. Miller, 1, NC)

Pacific Northwest land cover inventory (E. H.
Lathram, M)

Repetitive satellite imagery for the delineation and
monitoring of State/Federal Recreation Research
Management Zones (G. A. Thorley, B. J.
Niemann, Jr., 1, NC)

Spatial importance of open space and recreational
facilities in urban environments (G. A. Thorley,
W. H. Key, 1, NC)

Reservoirs. See Evapotranspiration
Resource and Land Investigations:
Colville Indian reservation case study on land-use planning
(E. T. Smith, 1, NC)
Council of State Governments:

Task force on natural resources and land-use information
and technology (Olaf Kays, I, NC) .

Data and information product evaluation (Olaf Kays, 1,
NC)

Designation of critical environmental areas (E. A. Imhoff, 1,
NC)
Environmental assessment (E. A. Imhoff, 1, NC)
Environmental planning and western coal development
(E. T. Smith, 1, NC)
Methodology for siting onshore facilities associated with
OCS development in the New England region
(W. W. Doyel, 1, NC)
Mined-area reclamation and related land-use planning (E. A.
Imhoff, 1, NC)
Regional workshops related to RALI-funded
methodological guidebooks (Olaf Kays, 1, NC)
South Florida environment (T. J. Buchanan, w, Miami)
State land inventory systems (Olaf Kays, 1, NC)
Utility corridor selection (W. W. Doyel, 1, NC)
Utility of geologic and soils maps to land-use planners
(W. W. Doyel, 1, NC)
Rhenium. See Minor elements and Ferro-alloy metals.
Saline minerals:
Mineralogy (B. M. Madsen, M)
States:
Colorado and Utah, Paradox basin (0. B. Raup, D)
New Mexico, Carlsbad potash and other saline deposits
(C. L. Jones, M)
Wyoming, Sweetwater County, Green River Formation
(W. C. Culbertson, D)
Salt-water intrusion.
See Marine hydrology
and Quality of water.

and Sedimentology.

349

Sedimentology:
Arctic fluvial processes, landforms (K. M. ,Scott, w, Laguna
Niguel, Calif.)
Bedload-transport research (W. W. Emmett, w, Boise, Idaho)
Channel morphology (L. B. Leopold, w, Berkeley, Calif.)
Circulation, San Francisco Bay (T. J. Conomos, w, M)
Coon Creek morphology (S. W. Trimble, w, NC)
Estimation of sediment yield (P. R. Jordan, w, Lawrence,
Kans.)
Estuarine intertidal environments (J. L. Glenn, w, D)
Highway sediment, Lake Tahoe (P. A. Glancy, w, Carson
City, Nev.)
Nemadji River sediment study (S. M. Hindall, w, Madison,
Wis.)
Sediment characteristics (L. M. Nelson, w, Tacoma, Wash.)
Sediment movement in rivers (R. H. Meade, Jr., W, D)
Sediment, Snake and Clearwater Rivers, Idaho (W. W.
Emmett, w, Boise)
Sediment transport phenomena (D. W. Hubbell, w, D)
Sedimentary petrology laboratory (H. A. Tourtelot, D)
States:
Alaska, coastal environments (A. T. Ovenshine, M)
Kansas (w, Lawrence):
Sediment and geometry of channels (W. R. Osterkamp)
Sediment, Arkansas River (W. R. Osterkamp)
Kentucky, sediment yields (W. F. Curtis, w, Pikesville)
Louisiana, sediment in Lake Verret basin (L. D. Fayard, W,
Baton Rouge)
Nevada, sediment transport, Incline Village (P. A. Glancy,
w, Carson City)
Ohio, sediment characteristics of Ohio streams (P. W.
Anttila, w, Columbus)
Pennsylvania (w, Harrisburg):
Evaluation of erosion-control measures used in highway
construction (L. A. Reed)
Study of cobble bed streams (J. R. Ritter)

See also Geochemistry, water; Geochronological investigations;
. Hy draulics, su rface flow; Hydrologic
data-collection and processing; Stratigraphy and
sedimentation; Urbanization, hydrologic effects.

Selenium. See Minor elements.
Silver. See Heavy metals; Lead, zinc, and silver.
Soil moisture:
Effects of grazing exclusion (G. C. Lusby, w, D)
Effects of vegetation changes (G. C. Lusby, w, D)
Infiltration and drainage (Jacob Rubin, w, M)
See also Evapotranspiration.
Spectroscopy:
Mobile spectrographic laboratory (D. J. Grimes, D)
Spectrographic analytical services and research (A. W. Helz,
NC; A. T. Myers, D; Harry Bastron, M)
X-ray spectroscopy (H. J. Rose, Jr., NC; Harry Bastron, M)
Stratigraphy and sedimentation:
Alaska Cretaceous (D. L. Jones, M)
Antler flysch, Western United States (F. G. Poole, D)
Cretaceous stratigraphy, western New Mexico and adjacent
areas (E. R. Landis, D)
East-coast Continental Shelf and margin (R. H. Meade, Jr.,
Woods Hole, Mass.)
Louisiana Continental Shelf (H. L. Berryhill, Jr., Corpus
Christi, Tex.)

350

Stratigraphy and sedimentation—Continued

Middle and late Tertiary history, Northern Rocky
Mountains and Great Plains (N. M. Denson, D)

Paleozoic rocks, Ruby Range, Montana (E. T. Ruppel, D)

Pennsylvanian System stratotype section (G. H. Wood, Jr.,
NC)

Phosphoria Formation, stratigraphy and resources (R. A.
Gulbrandsen, M)

Rocky Mountains and Great Basin, Devonian and
Mississippian conodont biostratigraphy (C. A.
Sandberg, D)

Sedimentary petrology laboratory (H. A. Tourtelot, D)

Sedimentary structures, model studies (E. D. McKee, D)

Stratigraphy, Florida and Alabama (J. A. Miller, w, Raleigh,

NC)
Williston basin, Wyoming, Montana, North Dakota, South
Dakota (C. A. Sandberg, D)
States:
Arizona:
Hermit and Supai Formations (E. D. McKee, D)
Magnetic chronology, Colorado Plateau and environs
(D. P. Elston, E. M. Shoemaker, Flagstaff)
California, Southern San Joaquin Valley, subsurface geology
(J. C. Maher, M)

Colorado, Jurassic stratigraphy (G. N. Pipiringos, D)

Nebraska, central Nebraska basin (G. E. Prichard, D)

Oregon-California (M):

Black sands (H. E. Clifton)
Hydrologic investigations, black sands (P. D. Snavely, Jr.)

Utah, Promontory Point (R. B. Morrison, D)

Wyoming (D):

Lamont-Baroil area (M. W. Reynolds)
South-central part, Jurassic stratigraphy (G. N.
Pipiringos)
See also Paleontology, stratigraphic, and specific areas under
Geologic mapping.
Structural geology and tectonics:
Contemporary coastal deformation (R. 0. Castle, M)
Rock behavior at high temperature and pressure (E. C.
Robertson, NC)

Structural studies, basin and range (F. G. Poole, D)

Tectonics of southeast Arizona (Harold Drewes, D)

Transcurrent fault analysis, western Great Basin,

Nevada-California (R. E. Anderson, D)

See also specific areas under Geologic mapping.

Talc, New York, Pope Mills and Richville quadrangles (C. E.
Brown, NC)

Tantalum. See Minor elements.

Thorium:

Analytical support (C. M. Bunker, D)

Investigations of thorium in igneous rocks (M. H. Staatz, D)

States:

Colorado (D):

Cochetopa area (J. C. Olson)
Thorium resources appraisal, Wet Mountains (T. J.
Armbrustmacher)

Montana-Idaho, Lemhi Pass area (M. H. Staatz, D)
Titanium, economic geology of titanium (Norman Herz, NC)
Tungsten. See Ferro-alloy metals.

Uranium:
Basin analysis of uranium-bearing Jurassic rocks of Colorado
Plateau, Arizona, Utah, Colorado, New Mexico
(Fred Peterson, D)

GEOLOGICAL SURVEY RESEARCH 1975

Uranium—Continued

Colorado Plateau tabular deposits, Colorado, New Mexico,
Arizona, Utah (R. A. Brooks, D)

Exploration techniques:

Geochemical techniques (R. A. Cadigan, D)

Geochemical techniques of halo uranium (J. K. Otton,
D)

Hydrogeochemical (C. G. Bowles, D)

Morrison Formation (L. C. Craig, D)

Ore-forming processes (H. C. Granger, D)

Organic chemistry of uranium, Wyoming, Colorado, New
Mexico, Utah, Texas (J. S. Leventhal, D)
Paleomagnetism applied to uranium exploration (R. L.

Reynolds, D)

Radium and other isotopic disintegration products in
springs and subsurface water (R. A. Cadigan, J. K.
Felmlee, D)

Resources of radioactive minerals (A. P. Butler, Jr., D)

Resources of United States and world (W. I. Finch, D)

Roll-type deposits, Wyoming, Texas (E. N. Harshman, D)

Southern High Plains (W. I. Finch, D)

United States:

Eastern:
Basin analysis as related to uranium potential in
Triassic sedimentary rocks (C. E. Turner, D)
Uranium vein deposits (R. I. Grauch, D)
Southwestern, basin analysis related to uranium potential
in Permian rocks (J. A. Campbell, D)
Western, relation of diagenesis and uranium deposits
(M. B. Goldhaber, D)

Uranium-bearing pipes, Colorado Plateau and Black Hills
(C. G. Bowles, D)

Uranium daughter products in modern decaying plant
remains, in soils, and in stream sediments (K. J.
Wenrich-Verbeek, D)

Uranium potential of Basin and Range Province, Arizona,
Nevada, Utah (J. E. Peterson, D)

Uranium in streams as an exploration technique (K. J.
Wenrich-Verbeek, D)

Volcanic source rocks (R. A. Zielinski, D)

States:

Arizona (R: E. Thaden, D)

Colorado (D):

Cochetopa Creek uranium-thorium area (J. C. Olson)
Marshall Pass uranium (J. C. Olson)
Schwartzwalder mine (E. J. Young)
Uranium-bearing Triassic rocks (R. D. Lupe)
New Mexico (D):
Acoma area (C. H. Maxwell)
Church Rock-Smith Lake (C. T. Pierson)
North Church Rock (A. R. Kirk)
San Juan Basin uranium (M. W. Green)
Sanostee (A. C. Huffman, Jr.)
Texas:
Coastal plain, geophysical and geological studies (D. H.
Eargle, Austin)
Tilden-Loma Alta area (K. A. Dickinson, D)
. Uranium disequilibrium studies (F. E. Senftle, NC)
Utah-Colorado (D):
Moab quadrangle (A. P. Butler, Jr.)
Uinta and Piceance Creek basins (L. C. Craig)
Wyoming (D):
Badwater Creek (R. E. Thaden)

INVESTIGATIONS IN PROGRESS 351

Uranium—Continued

States—Continued
Wyoming—Continued
Crooks Peak quadrangle (L. J. Schmitt, Jr.)
Granite as a source rock of uranium (J. S. Stuckless, D)
Northeastern Great Divide Basin (L. J . Schmitt, Jr.)
Powder River Basin (E. S. Santos)
Sagebrush Park quadrangle (L. J. Schmitt, Jr.)
Stratigraphic analysis of western interior Cretaceous

uranium basins (H. W. Dodge, Jr.)

Urban geology:

States:
Alaska (D):
Anchorage area (Ernest Dobrovolny)
Juneau area (R. D. Miller)
Sitka area (L. A. Yehle)
Sniall coastal communities (R. W. Lemke)
Arizona, Phoenix-Tucson region resources (T. G. Theodore,
M)
California (M):
Coastal geologic processes (K. R. Lajoie)
Earth science planning applications (W. J. Kockelman)
Flatlands materials and their land-use significance (E. J.
Helley)
Geologic factors in open space (R. M. Gulliver)
Hillside materials and their land-use significance (C. M.
Wentworth, Jr.)
Malibu Beach and Topanga quadrangles (R. F. Yerkes)
Palo Alto, San Mateo, and Montara Mountain quadrangles
(E. H. Pampeyan)
Point Dume and Triunfo Pass quadrangles (R: H.
Campbell)
Regional slope stability (T. H. Nilsen)
San Francisco Bay region, environment and resources
' planning study:
Bedrock geology (M. C. Blake)
Marine geology (D. S. McCulloch)
Open space (C. S. Danielson)
San Andreas fault—basement studies (D. C. Ross)
San Andreas fault—basin studies (J. A. Bartow)
San Andreas fault—regional framework (E. E. Brabb)
San Andreas fault—tectonic framework (R. D. Brown)
San Mateo County cooperative (H. D. Gower)
Sargent-Berrocal fault zone (R. J. McLaughlin, (D. H.
Sorg)
Sediments, engineering-geology studies (D. R. Nichols,
Julius Schlocker) ’
Seismicity and ground motion (W. B. Joyner)
Colorado (D):
Denver-Front Range urban corridor, remote sensing
(T. W. Offield)
Denver metropolitan area (R. M. Lindvall)
Denver mountain soils (regolith), Front Range urban
corridor (K. L. Pierce, P. W. Schmidt)
Denver urban area, regional geochemistry (H. A.
Tourtelot)
Denver urban area study:
Geologic map, Boulder-Ft. Collins-Greeley area (R. B.
Colton)
Geologic map, greater Denver area (D. E. Trimble)

Urban geology—Continued

States—Continued
Colorado~Continued
Denver urban area study—Continued
Geologic map, Colorado Springs-Castle Rock area
(W. R. Hansen)
Land-use classification, Colorado Front Range urban
corridor (W. R. Hansen, L. B. Driscoll, D)
Engineering geology mapping research, Denver region
(H. E. Simpson)
Terrain mapping from Skylab data (H. W. Smedes)
Connecticut (Middletown):
Connecticut Valley urban area study:
Distribution of clay deposits (Fred Pessl, Jr.)
Depth to bedrock (Fred Pessl, Jr.)
Maryland, Baltimore-Washington urban area study (J. T.
Hack, NC)
Massachusetts, Boston and vicinity (C. A. Kaye, Boston)
Montana, geology for planning, Helena region (R. G.
Schmidt, NC)
New Mexico, geology of urban development (H. E. Malde,
D)
Pennsylvania :
Areas of subsidence due to coal mining (K. O. Bushnell,
Slippery Rock)
Coal mining features, Allegheny County (W. E. Davies,

NC)

Disturbed ground, Allegheny County (R. P. Briggs,
Carnegie) .

Greater Pittsburgh regional studies (R. P. Briggs,
Carnegie)

Landslides, Allegheny County (R. P. Briggs, Carnegie)
Land use affected by landsliding (R. P. Briggs, Carnegie)
Limitations of land, Allegheny County (R. P. Briggs,
Carnegie)
Pittsburgh coal bed outcrop (K. O. Bushnell, Slippery
Rock)
Rock types, Allegheny County (W. R. Kohl, Pittsburgh)
Susceptibility to landsliding, Allegheny County (J. S.
Pomeroy, NC) \
Upper Freeport coal bed outcrop (K. O. Bushnell,
Slippery Rock)
South Dakota, Rapid City area (J. M. Cattermole, D)
Utah, Salt Lake City and vicinity (Richard Van Horn, D)
Virginia, geohydrologic mapping of Fairfax County (A. J.
Froelich, NC)

Urban hydrology?

Geohydrology, urban planning (J. R. Ward, w, Lawrence,
Kans.)

Hydrogeologic regime in land-use planning (Seymour
Subitzky, w, Trenton, N.J.)

Hydrogeology of landfills (H. H. Zehner, w, Louisville,
Ky.)

Investigation of urban hydrologic parameters (W. J.
Schneider, w, NC)

RALI southern Florida (T. J. Buchanan, w, Miami, Fla.)

Studies for tunnel construction (E. M. Cushing, w, NC)

Urban areas reconnaissance (W. E. Hale, w, Albuquerque,
N. Mex.)

Urban sedimentology (H. P. Guy, w, NC)

352

Urban hydrology—Continued

West Coast gasline environmental impact statement (D. M.
Culbertson, w, M)
States and territories:

Alabama:
Jefferson County floodway evaluation (A. L. Knight, w,
Tuscaloosa)
Urban study, Madison County (R. C. Christensen, w,
Huntsville)

Arizona, Tucson-Phoenix urban area pilot study (E. S.
Davidson, w, Tucson)
California:
Erosion, transportation, and deposition of sediment
(W. M. Brown III, w, M)
Flood inundation (J. T. Limerinos, w, M)
Land waste disposal and pollution potential (K. S. Muir,
w, M)
Morphology, San Francisquito (J. R. Crippen, w, M)
Perris Valley (M. W. Busby, w, Laguna Niguel)
Poway Valley (J. A. Singer, w, Laguna Niguel)
San Francisco Bay area, urbanization (R. D. Brown, Jr.,
w, M)
Colorado:
Climatological atlases, Colorado Front Range urban
corridor (W. R. Hansen, D)
Denver urbén-area pilot study, effects on water resources
(E. R. Hampton, w, D)
Distributi'on and thickness of mountain soils (K. L.
Pierce, D)
Flood frequency, urban areas (L. G. Ducret, Jr., w, D)
Flood-prone area maps, Colorado Springs-Castle Rock
area, Colorado Front Range urban corridor (J. F.
McCain, w, D)
Storm runoff quality, Denver (J. C. Briggs, w, D)
Connecticut:
Connecticut Valley urban area study (Fred Pessl, Jr.,
Middletown)
Connecticut Valley urban pilot study (R. B. Ryder, w,
Hartford)
Drainage areas (Fred Pessl, Jr. Middletown)
Florida:
Bay Lake (A. L. Putnam, w, Winter Park)
Tampa Bay region (G. E. Seaburn, w, Tampa)
Hawaii, hydrology, sediment Moanalua (C. J. Ewart, w,
Honolulu)
Illinois, quality of water monitoring, Bloomington-Normal
(B. J. Prugh, Jr., w, Champaign)
Iowa, flow models, Walnut Creek (0. G. Lara, w, Iowa City)
Kentucky (w, Louisville):
Hydraulics of bridge sites (C. H. Hannum)
Water use and availability (D. C. Griffin)
Maryland, Rock Creek-Anacostia River (T. H. Yorke, Jr., W,
College Park)
Mississippi (w, Jackson):
Bridge-site investigations (C. H. Tate)
Hydraulic performance of bridges (B. E. Colson)
Missouri,
stream hydrology, St. Louis (T. W. Alexander, w, Rolla)
New Mexico, hydrologic test sites (F. C. Koopman, w,
Albuquerque)
Ohio (P. W. Anttila, w, Columbus)

GEOLOGICAL SURVEY RESEARCH 1975

Urban hydrology—Continued .
States and territories—Continued
Oregon, Portland runoff study plan (D. J. Lystrom, w,
Portland)
Pennsylvania (w, Harrisburg):
Philadelphia (T. G. Ross)
Storm-water measurements (T. G. Ross)
Puerto Rico, Rio Piedras (V. J. Latkovitch, w, San Juan)
South Carolina, hydraulic-site reports (B. H. Whetstone, w,
Columbia)
Texas:
Austin (M. L. Maderak, w, Austin)
Dallas County urban study (B. B. Hampton, w, Fort
Worth)
Dallas urban study (B. B. Hampton, w, Fort Worth)
Fort Worth urban study (R. M. Slade, Jr., w, Fort Worth)
Houston urban study (S. L. Johnson, w, Houston)
San Antonio urban study (R. D. Steger, w, San Antonio)
Washington (w, Tacoma):
Puget Sound urban area studies:
Availability and relative value of ground water,
Seattle-Tacoma area (B. L. Foxworthy)
Solid waste disposal sites, Seattle-Tacoma area (R. T.
Wilson)
Waterwell records in land-use planning (B. L.
Foxworthy)
Wood-waste disposal and water quality, Snohomish
County (B. L. Foxworthy, B. D. Robertson)
Urbanization, hydrologic effects:
Effect on flood flow, North Carolina, Charlotte area (W. H.
Eddins, w, Raleigh)
Vegetation:
Elements in organic-rich material (F. N. Ward, D)
See also Plant ecology.
Volcanic-terrane hydrology. See Artificial recharge.
Volcanology:
Cascade volcanoes, geodimeter studies (D. A. Swanson, M)
Cauldron and ash-flow studies (R. L. Smith, NC)
Columbia River basalt (D. A. Swanson, M)
Regional volcanology (R. L. Smith, NC)
Volcanic ash chronology (R. E. Wilcox, D)
Volcanic hazards (D. R. Crandell, D)
States:
Arizona, San Francisco volcanic field (J. F. McCauley, M)
Hawaii (M, except as otherwise noted):
Hawaiian Volcano Observatory (R. I. Tilling, Hawaii
National Park)
Seismic studies (P. L. Ward)
Submarine volcanic rocks (J. G. Moore)

Idaho (D):
Central Snake River Plain, volcanic petrology (H. E.
Malde)
Eastern Snake River Plain region (P. L. Williams, H. J.
Prostka)

Snake River basalt (P. L. Williams, H. J. Prostka)
Montana, Wolf Creek area, petrology (R. G. Schmidt, NC)
New Mexico, Valles Mountains, petrology (R. L. Smith, NC)
Wyoming, deposition of volcanic ash in the Mowry Shale

and Frontier Formation (G. P. Eaton, D)
Water resources:
Central Region field coordination (J. L. Poole, w, D)

INVESTIGATIONS IN PROGRESS 353

Water resources-Continued

Chattahoochee intensive river quality (R. N. Cherry, w,
Atlanta, Ga.)
Columbia-North Pacific ground water (B. L. Foxworthy, w,
Tacoma, Wash.)
Comprehensive studies, Pacific Northwest (L. E. Newcomb,
w, M)
Dams, weirs, and flumes (H. J. Tracy, w, Atlanta, Ga.)
Data coordination, acquisition and storage:
NAWDEX Project (S. M. Lang, w, NC)
Systems Analysis Laboratory (N. C. Matalas, w, NC)
Water Data Coordination (R. H. Langford, w, NC)
East Triassic waste-disposal study (G. L. Bain, w, Raleigh,
N.C.)
Environmental impact analyses support (W. J. Schneider, w,
NC)
Evaluation of land treatment (R. F. Hadley, w, D)
Foreign countries:
Canada:
Gasline environmental impact statement (D. M.
Culbertson, w, M)
Gas pipeline (V. K. Berwick, w, Anchorage, Alaska)
Brazil, surface water, national program (D. C. Perkins, w,
Rio de Janeiro)
India, ground-water investigations in states of Madhya
Pradesh, Gujarat, Maharashtra and Mysore (J. R.
Jones, w, NC)
Kenya (w, Nairobi):
Hydrogeology of eastern Kenya (W. V. Swarzenski)
'Range water resources (N. E. McClymonds)
Nepal, hydrogeology off Terai region (G. C. Tibbitts, Jr.,
w, Katmandu)
Yemen, water and mineral survey, north Yemen (J. R.
Jones, w, San‘a’)
General hydrologic research (R. L. Nace, w, Raleigh, N.C.)
Ground-water appraisal, middle Atlantic region (Allen
Sinnott, w, Trenton, N.J.)
Ground-water appraisal, New England region'(Allen Sinnott,
. w; Trenton, N.J.)
Ground water, Missouri Basin (0. J. Taylor, w, D)
Ground-water, Southeastern States (D. J. .Cederstrom, w,
NC)
Intensive river quality assessment (D. A. Rickert, w,
Portland, Oreg.)
Intermediate-depth drilling (L. C. Dutcher, w, M)
Madison Limestone plan of study (E. M. Cushing, w, D)
National assessment (S. M. Lang, w, NC)
Northeast drought (M. T. Thomson, w, NC)
Northeastern Region field coordination (J. W. Geurin, w,
NC)
Northwest water-resources data center (N. A. Kallio, w,
Portland, Oreg.)
Off-the-road vehicle use (C. T. Snyder, w, M)
Pilot study, greater Pittsburgh (R. M. Beall, w, Pittsburgh,
Pa.)
Powell arid lands centennial (R. F. Hadley, w, D)
Quality-of-water accounting network (R. J. Pickering, w,
NC)
Rating extensions (K. L. Wahl, w, NC)
Rehabilitation potential, energy lands (L. M. Shown, w, D)
Reservoir bank storage study (T. H. Thompson, w, M)

Water resources—Continued

‘

Southeastern Region field coordination (M. D. Hale, w,
Atlanta, Ga.)
Subsurface waste emplacement potential (P. M. Brown, w,
Raleigh, N.C.)
Water-resources activities (J. R. Carter, w, D)
Water-supplies from Madison Limestone (F. A. Swenson, w,
D)
Water-supply exploration (N. J. King, w, D)
Waterway treaty engineering studies (J. A. Bettendorf, w,
NC) '
Western Region field coordination (G. L. Bodhaine, w, M)
States and territories:
Alabama (w, Montgomery, except as noted otherwise):
Cretaceous aquifer simulation (R. A. Gardner)
Drainage areas (C. O. Ming)
Geology and hydrology along highway locations and rest
areas (J. C. Scott)
Hydraulics of bridge design (J. W. Board)
Low flows of Alabama streams (W. J. Powell, E. C.
Hayes, w, Tuscaloosa)
Plans, reports, and information (W. J. Powell, w,
Tuscaloosa)
Tennessee River basin (J. R. Harkins, w, Tuscaloosa)
Alaska (w, Anchorage, except as noted otherwise):
Alaskan gas pipeline environmental impact statement
(A. J. Feulner)
Arctic resources (J. M. Childers)
Coal resources study (A. J. Feulner)
Cordova water resources (G. S. Anderson)
Hydrology:
Anchorage area (G. O. Balding)
Greater Juneau Borough (J. A. McConaghy, Juneau)
Hydrologic environment of the trans-Alaska pipeline
system (TAPS) (J. M. Childers)
Hydrologic planning, resource team (A. J. Feulner)
Hydrologic studies for Alaskan Air Command (R. J.
Madison)
Kenai Peninsula Borough (G. S. Anderson)
Municipal water supply (D. A. Morris)
Surface water, Valdez-Copper Center project (C. E.
Sloan)
American Samoa, surface-water resources (Iwao Matsuoka,
w, Honolulu, Haw.)
Arizona:
Black Mesa hydrologic study (R. M. Myrick, w, Tucson)
Black Mesa monitoring program (G. W. Levings, w,
Flagstaff)
Channel loss study (T. W. Anderson, w, Phoenix)
Coconino Sandstone water budget, Navajo County (L. J.
Mann, w, Flagstaff)
Copper Basin study (B. W. Thomsen, w, Phoenix)
Ground-water appraisal, Lower Colorado River (E. S.
Davidson, w, Tucson)
National eutrophication survey (E. B. Hodges, w, Tucson)
Sedona ground-water availability (G. W. Levings, w,
Flagstaff)
Arkansas (w, Little Rock):
Bayou Bartholomew systems study (M. E. Broom)
Cache River aquifer-stream system (M. E. Broom)
Characteristics of streams (M. S. Hines)

354 GEOLOGICAL SURVEY RESEARCH 1975

Water resources—Continued
States and territories-Continued
Colorado (w, D, except as noted otherwise )—-Continued

Water mources—Continued
States and territories—Continued
Arkansas (w, Little Rock )-Continued
Ground-water appraisal, AWRRB (M. S. Bedinger) Ground water—Continued
Investigations and hydrologic information (R. T.‘ Southwestern Colorado (E. R. Hampton)
Sniegocki) U.S. Bureau of Mines prototype mine (J. B. Weeks)
National eutrophication survey (M. S. Hines) Hydrology 1
Red River navigation study (A, H_ Ludwig) Arkansas River basin (0. J. Taylor, w, Pueblo)
Time-of-travel study (T. E. Lamb) E1 P 930 County (13- L- Bingham)
Urban effects on Hot Springs (M_ S. Bedinger) Parachute-Roan Creek Basin (G. H. Leavesley)
California (w, M, except as noted otherwise): Rocky Flats (R. T. Hurr)
Antelope Valley ground-water model (S. G. Robson, w, San Luis Valley (0. J. Taylor, w, Pueblo)
Laguna Niguel) South Platte River basin, Henderson to State line
Ground water: (R. T. Hurr)
Antelope Valley area (F. W. Geissner, w, Laguna National eutrophication survey (H. E. Petsch, Jr.)
Niguel) National Parks (J. E. Biesecker)
City of Modesto, ground-water planning (R. W. Page, Quality of water:

Sacramento)

Clovis (R. W. Page, w, Sacramento)

Death Valley National Monument hydrologic
reconnaissance (G. A. Miller, w, Laguna Niguel)

Geohydrology of Garner Valley (T. J. Durbin, w,
Laguna Niguel)

Geochemical investigation (S. G. Robson)
Hydrology of Jefferson County (W. E. Hofstra)
Sediment yield, Piceance Basin (V. W. Norman)
Water-quality monitor network (J. E. Biesecker)
Water resources, Boxelder alluvium (R. T. H urr)
West slope aquifers (E. R. Hampton)

Geohydrology, Round Valley (K. S. Muir) Spring hydraulics (J. B. Weeks)
Indian Wells Valley (J. H. Koehler, w, Laguna Niguel) Water resources, Park-Teller County (0. J. Taylor, w,
Joshua Tree'(G. A. Miller, w, Laguna Niguel) Pueblo)
Madera area, ground-water model (W. D. Nichols, w, Connecticut (w, Hartford):
Sacramento) Hydrogeology, south-central Connecticut (R L. Melvin)
Redlands nitrate study (L, A. Eccles, w, Laguna Hydrology of Canaan hydro site (F. H. Ruggles, Jr.)
Niguel) Part '7, Upper Connecticut River basin (R. B. Ryder)
Sacramento Valley (R, M. Bloyd, Jr., w, Sacramento) Part 8, Quinnipiac River basin (D. L. Mazzaferro)
Santa, Barbara-San Luis Obispo (G_ A, Miller, w, Part 9, Farmington River basin (H. T. Hopkins)
Laguna Niguel) Part 10, lower Connecticut River basin (L. A. Weiss)
Santa Cruz (K. S. Muir) Short-term studies (F. H. Ruggles, Jr.)
South California (W. R. Moyle, Jr., w, Laguna Niguel) Delaware, aquifer-model studies (R. H. Johnston, w, Dover)
Withdrawals, statewide (H. T. Mitten, w, Sacramento) Florida (w, Tallahassee, except as noted otherwise):
Indian reservations (J. W. Wark) Bridge-site studies (W. C. Bridges)
Quality of water: Broward County (C. B. Sherwood, w, Miami)
Ground-water quality, Suisun Bay (Chabot Kilburn) Digital model, Palm Beach County (L. F. Land, w,

Highway erosion, Tahoe basin (C. G. Kroll, w, Tahoe Miami)

City) Ground water:
Lakes and reservoirs (R. C. Averett) Aquifer mapping, south Florida (K. E. Vanlier, w,
Trace metals control, Sacramento (R. F. Ferreira, w, Miami)

Sacramento) Artificial recharge, west-central Florida (W. C. Sinclair,

Surface water: ’ w, Tampa)
Floods—small drainage areas (A. O. Waananen) Coastal springs (W. C. Sinclair, w, Miami)
National eutrophication survey (J. R. Crippen) Fort Lauderdale area, special studies (H. J. McCoy, w,
Sediment, Redwoods National Park (J. M. Knott) Miami)
Urbanization, Santa Clara County (J. M. Knott) Hallandale area, (H. W. Bearden, w, Miami)
Colorado (w, D, except as noted otherwise): Hollywood area (H. W. Bearden, w, Miami)
Coal rehabilitation (W. E. Hofstra) Hydrogeology, middle Peace basin (W. E. Wilson III, w,

Evaporation, Colorado lakes (D. B. Adams) Tampa)

Ground water: Hydrology, Cocoa well field (J. B. Holly, w, Winter
Aquifer testing (J. B. Weeks) ‘ Park)
Geophysical logging (J. B. WeekS) Hydrology, Manatee County (Horace Sutcliffe, Jr., w,
High Plains of Colorado (W. E. Hofstra) Sarasota)
Near Lake Minnequa (O. J. Taylor, w, Pueblo) Hydrology, Sarasota County (Horace Sutcliffe, Jr., w,
Potentiometric surface mapping (J. B. Weeks) Sarasota)

Recharge, Bijou Creek (W. E. Hofstra)
Southern Ute lands (E. R. Hampton)

North Brevard County aquifer study (H. F. Grubb, w,
Winter Park) '

INVESTIGATIONS IN PROGRESS

Water resources-Continued
States and territories—Continued
Florida (w, Tallahassee, except as noted otherwise)—
Continued
Ground water—Continued

Ochlockonee River basin investigation (C. A. Pascale)

Oklawaha shallow aquifer study (Warren Anderson, w,
Winter Park)

Palm Beach County flatlands (K. E. Vanlier, w, Miami)

Peace and Alafia River basins (A. F. Robertson, w,
Tampa)

Potentiometric St. Petersburg-Tampa (C. B. Hutchin-
son, w, Tampa)

Recharge, Orange County (P. W. Bush, w, Winter Park)

Salt-water intrusion, Fernandina (R. W. Fairchild, w,
Jacksonville)

Sand-gravel aquifer, Pensacola (Henry Trapp)

Santa Fe River basin (J. C. Rosenau)

Sewage effluent disposal, irrigation (L. J. Slack)

Shallow aquifer, Brevard County (J. M. Frazee, Jr., w,

Winter Park)

Shallow aquifers, Alafia and Peace (J. D. Hunn, w,
Tampa)

Southwestern Hillsborough County (J. W. Stewart, w,
Tampa)

Springs of Florida (J. C. Rosenau, w, Ocala)

Technical assistance, Hillsborough County (J. W.
Stewart, w, Tampa)

Technical assistance, south Florida (Howard Klein, w,
Miami)

Urban hydrology, Englewood area (H. Sutcliffe, Jr., w,
Sarasota)

Verna well field (Horace Sutcliffe, Jr., w, Sarasota)

Water resources, Duval-Nassau (G.W. Leve, w,
Jacksonville)

Water resources, Martin County (H. G. Rodis, w,
Miami)

Water resources, Tequesta (L. F. Land, w, Miami)
Water-supply potential, Green Swamp (H. F. Grubb, W,

Winter Park)

Hydrogeologic maps, Seminole County (W. D. Wood, w,
Winter Park)

Hydrologic suitability study (L. V. Causey, w,
Jacksonville)

Hydrology of lakes (G. H. Hughes)
Hydrology, Volusia County (P. W. Bush, w, Winter Park)
Lake recharge investigations (Warren Anderson, w, Winter
Park) .
Lee County (D. H. Boggess, w, Ft. Myers)
Mapping, Green Swamp (B. F. McPherson, w, Miami)
Marion County flood studies (Warren Anderson, w,
Ocala)
Osceola County (J. M. Frazee, w, Winter Park)
Palm Beach County (H. G. Rodis, w, Miami)
Quality of water:
Chemistry of Florida streams (D. A. Goolsby)
Estuarine hydrology, Tampa Bay (C. R. Goodwin, w,
Tampa)
Landfill and water quality (J. E. Hull, w, Miami)
Solid waste, Hillsborough County (Mario
Fernandez, Jr., w, Tampa)

355

Water resources—Continued
States and territories—Continued
Florida (w, Tallahassee, except as noted otherwise)—
Continued
Quality of water—Continued
Solid waste, St. Petersburg (Mario Fernandez, Jr., w,
Tampa)
Subsurface disposal, Pinellas (J. J. Hickey, w, Tampa)
Technical assistance, Department of Pollution Control
(D. A. Goolsby)
Water supply, Temple Terrace (J. W. Stewart, w,
Tampa)
Riviera Beach investigations (L. F. Land, w, Miami)
Seminole County (C. H. Tibbals, w, Winter Park)
Special studies, statewide (C. S. Conover)
Surface water:
Drawdown of Lake Carlton (Warren Anderson, w,
Winter Park)
Hydrology study, Fakah'atchee Strand (L. J. Swayze,
w, Miami)
Lakes in southwest Florida (J. D. Hunn, w, Tampa)
Manasota planning report (Horace Sutcliffe, Jr., w,
Sarasota)
Manasota technical assistance (Horace Sutcliffe, Jr., w,
Sarasota)
Technical assistance:
Northwest Florida Water Management District (J. C.
Rosenau)
St. Johns River (G. W. Leve, w, Jacksonville)
Suwannee River Water Management District (J. C.
Rosenau)
Technical support, ground water (A. F. Robertson, w,
Tampa)
’I‘ri-county investigation (C. B. Bentley, w, Jacksonville)
Waccasassa Basin hydrology (G. F. Taylor, w, Winter
Park)
Water atlas (S. D. Leach)
Water resources, Hendry County (T. M. Missimer, w,
Miami)
Water resources of Orange County (C. H. Tibbals, w,
Winter Park)
Western Collier County (H. J. McCoy, w, Miami)
Georgia (w, Doraville, except as noted otherwise):
Cretaceous (R. C. Vorhis)
Information system (J. R. George)
National eutrophication survey (R. F. Carter)
Northwest Georgia geology and water (C. W. Cressler, w,
Calhoun)
Valdosta hydrology (R. E. Krause)
Hawaii (w, Honolulu):
Data management, Guam (C. J. Huxel, Jr.)
Ground water in Waialua, Oahu (R. H. Dale)
Kauai water resources survey (R. J. Burt)
Regional study (B. L. Jones)
Topical studies (F. T. Hidaka)
Idaho (w, Boise):
Flow in Silver Creek, Idaho (J. A. Moreland)
Hydrologic environment, White Clouds area (W. W.
Emmett)
Kootenai Board—WWT (H. K. Hall)
National eutrophication survey (H. A. Ray)

356

Water resources—Continued
States and territories—Continued
Idaho (w, Boise)—-Continued
Snake Plain aquifer studies (E. G. Crosthwaite)
Illinois, stream dispersion (L. G. Toler, w, Champaign)
Indiana (w, Indianapolis):
Ground water, Indianapolis hydrology (William Meyer)
Ground water near Ft. Wayne (Michael Planert)
Maumee River Basin level B (Michael Planert)
Streamflow summaries (R. G. Horner)
Time of travel regionalization (S. E. Eikenberry)
Iowa (w, Iowa City):
Bedrock mapping (R. E. Hansen)
Cambrian-Ordovician aquifer (W. L. Steinhilber)
Low flow, Iowa streams (O. G. Lara)
National eutrophication survey (I. L. Burmeister)
Sediment data (J. R. Schuetz)
South-central (J. W. Cagle, Jr.)
Water resources, east-central Iowa (K. D. Wahl)
Kansas (w, Lawrence, except as noted otherwise):
Kansas-Oklahoma Arkansas River Commission (E. R.
Hedman)

Miscellaneous investigations (H. G. O’Connor)

National eutrophication survey (M. L. Thompson)

Numerical modeling of Little Arkansas River basin,
south-central Kansas (J. C. Halepaska, D. B.
Richards)

Prairie National Park (D. R. Albin)

Saline ground-water resources of Kansas (K. M. Keene)

Report processing (H. E. McGovern)

Saline water from Permian rocks (D. R. Albin)

Water supply in droughts (F. C. Foley)

Kentucky (w, Louisville):
Covington-Lexington-Louisville triangle (D. S. Mull)
Ground water:

Alluvium of major Ohio River tributary streams (P. D.
Ryder)
Hydrology, Princeton area (R. O. Plebuch)
Ohio River valley (P. D. Ryder)
Hydrology, Beaver Creek strip mine (J. A. McCabe)
Kentucky River Area Development District project
(R. W. Davis)
London-Corbin area (R. W. Davis)
National eu'trophication survey (H. C. Beaber)
Louisiana (w, Baton Rouge):
Baton Rouge area (C. D. Whiteman, Jr.)
New Orleans area (D. C. Dial)
Ground water:
Gramercy area (G. T. Cardwell)
Kisatchie Forest area (J. E. Rogers)
Terrace aquifer, central Louisiana (T. H. Sanford)
Water quality in upper Mississippi River Delta alluvium
(M. S. Whitfield)
Reports on special topics (M. F. Cook)
Site studies (R. L. Hosman)
Southwestern part (D. J. Nyman)
Surface water:
Flood hydraulics and hydrology (B. L. Neely, Jr.)
National eutrophication survey (A. J. Calandro)
Velocity of Louisiana streams (A. J. Calandro)
Tangipahoa-Tchefuncte River basins (D. J. Nyman)

GEOLOGICAL SURVEY RESEARCH 1975

Water resources—Continued

States and territories—Continued

Maine (w, Augusta):

Ground water, North Wi’ndham-Freeport (G. C.
Prescott, Jr.)
Highway research (R. A. Morrill)
Maryland (w, Parkville, except as noted otherwise):
Baltimore-Washington urban hydrology (W. F. White)
Geohydrologic studies, Carroll County (J. M. Weigle)
Ground-water resources-urbanization, Harford County
(L. J. Nutter)

Low-flow studies in Maryland (K. R. Taylor)

National eutrophication survey (K. R. Taylor)

Special studies, ground water (E. G. Otton)

Trap efficiency, Rock Creek (T. H. Yorke, Jr., College
Park)

Massachusetts (w, Boston):

Charles River basin (E. H. Walker)

Coastal southeastern Massachusetts, Wareham to Seekonk
(G. D. Tasker)

Connecticut River lowlands (E. H. Walker)

Deicing chemicals, ground Water (L. G. Toler)

Mathematical. modeling of Ipswich River basin (I. C.
James II)

Nashua River basin (R. A. ,Brackley)

Northeastern coastal basins (F. B. Gay)

Northeastern river basins (R. A. Brackley)

Southeastern coastal drainage (J. R. Williams)

Water and related land resources for southeastern New
England (M. H. Frimpter)

Michigan (w, Okemos, except as noted otherwise):

Erosion in St. Joseph Basin (T. R. Cummings)

Geohydrology, environmental planning (W. B. Fleck)

Ground-water models, Muskegon County (W. B. Fleck)

Ground water, West Upper Peninsula (C. J. Doonan, w,
Escanaba)

Minnesota (w, St. Paul):

Deep aquifers near Broote'n (H. O. Reeder)

Evaluation, quality-of—water data for management (S. P.
Larson)

Ground water in Park Rapids area (J. O. Helgesen)

Impact of copper-nickel mining (P. G. Olcott)

Lake Superior watersheds (G. F. Lindholm)

Reconnaissance of sand-plain aquifers
Anderson, Jr.)

River basin summaries (G. F. Lindholm)

Twin Cities level B study (C. R. Collier)

Water budget, Shagawa Lake (D. W. Ericson)

Mississippi (w, Jackson):

Alcorn, Itawamba, Prentiss, and Tishomingo Counties
(B. E. Wasson)
Ground water:

Aquifer maps for Mississippi (E. H. Boswell)

Ground-water use (J. A. Callahan)

Hydrology, Tennessee-Tombigbee (J. D. Shell)

Southern delta (J. M. Bettandorff)

Water, subcoastal Mississippi (J. V. Brahana)
Information to the public (K. V. Wilson)
National eutrophication survey (J. D. Shell)
Waste assimilation (J. K. Arthur)

Water in north delta (G. J. Dalsin)

(H. w.

INVESTIGATIONS IN PROGRESS 357

Water resources—Continued
States and territories--Continued
New Jersey (w, Trenton)—Continued
Water resources, Wharton Trace (William Kam)
Water temperatures (M. G. McDonald)
New Mexico (w, Albuquerque):

Water resourcerContinued
States and territories—Continued
Mississippi (w, Jackson )—Continued
Water use (J. A. Callahan)
Missouri (w, Rolla):
Ground-water resources - Springfield area (L. F. Emmett)

National eutrophication survey (John Skelton)
Small lakes in Missouri (J. H. Barks)
Water quality, scenic riverways (J. H. Barks)
Montana (w, Helena, except as noted- otherwise):
Ground water:
Central Powder River valley (W. R. Miller, w, Billings)
Clark Fork basin (A. J. Boettcher)
Fort Belknap (R. D. Feltis)
Fort Union Formation (W. B. Hopkins, w, Billings)
Hydrology, lower flathead (A. J. Boettcher)
Madison Group (W. R. Miller, w, Billings)
Mined lands reclamation (W. R. Hotchkiss)
Northern Judith basin (R. D. Feltis, w, Billings)
Quality of water near Libby (A. J. Boettcher)
“Saline seeps” (R. G. McMurtrey)
Southern Powder River valley (W. R. Miller)
Special investigations (D. L. Coffin)
Water availability, Madison (W. R. Miller, w, Billings)
Water supplies for national parks, monuments, and
recreation areas (D. L. Coffin)
Mining effects, shallow water (R. S. Roberts)
, National eutrophication survey (R. R. Shields)
Nebraska (w, Lincoln):
Assessment of ground-water quality (L. R. Petri)
Ground-water resources of Boyd County (V. L. Souders)
Ground-water use, Blue River basin (E. K. Steele, Jr.)
Hydrogeology of southwest Nebraska (E. G. Lappala)
Movement of nitrogen into aquifers (L. R. Petri)
National eutrophication survey (G. G. Jamison)
Seward County (M. J. Ellis)
Time—of—travel data (L. R. Petri)
Water in" the Loup River basin (R. Bentall)
Nevada (w, Carson City):
Aquifers in the Fallon area (P. A. Glancy)
National eutrophication survey (D. 0. Moore)
Smith Valley (F. E. Rush)
Statewide reconnaissance (F. E. Rush)
Topical studies (J. P. Monis)
Water supply, Cold Spring Valley (A. S. Van Denburgh)
Water supply, mining districts (H. A. Shamberger)
New Hampshire, ground-water reconnaissance, river basins
(J. E. Cotton, w, Concord)
New Jersey (w, Trenton):
Automatic processing of ground-water data (William
Kam)
Base-flow studies (E. G. Miller)
Camden County, geology and ground-water resources
(G. M. Farlekas)
Miscellaneous Federal work (Harold Meisler)
Nitrification in southern New Jersey (J. C. Schornick, Jr.)
Problem river studies (J. C. Schornick, Jr.)
Quantification non-point pollution (J. C. Schornick, Jr.)
Short-term studies (Harold Meisler)
Test drill geophysical logging (J. E. Luzier)
Time-of-travel study (E. A. Pustay)

Bureau of Indian Affairs water-supply investigations
(F. P. Lyford)
Cimarron Basin analysis (P. L. Soule)
Coal-lease areas, northwest New Mexico (Kim Orig)
Ground water:
Capitan Reef (W. L. Hiss)
Gallup ground-water exploration (W. L. Hiss)
Harding County (F. D. ’I‘rauger)
Miscellaneous activities, State Engineer (J. E. Cooper)
White Sands Missile Range, water levels and pumpage
(H. D. Hudson)
Surface water:
National eutrophication survey (L. P. Denis)
Pojoaque River analyses (L. J. Reiland)
New Mexico data bank (P. L. Soule)
Rio Grande Commission (P. L. Soule)

New York (w, Albany, except as noted otherwise):

Basin recharge with sewage effluent (R. C. Prill, w,
Mineola)

Column-basin studies (M. S. Garber, w, Mineola)

Deep-well waste disposal in western New York (R. M.
Waller)

Delaware basin water-quality study (G. E. Williams)

Hydrogeology Qf/southeast Nassau County (H. F. H. Ku,
w, Mineola)

Hydrologic modeling (R. T. Getzen, w, Mineoloa)

Long Island recharge (R. C. Prill, w, Mineola)

Long Island water quality (S. E. Ragone, w, Mineola)

Nassau County, ground-water system study (Chabot
Kilburn, w, Mineola)

Suffolk County, hydrologic conditions (H. M. Jensen, w,
Mineola)

Suffolk County, water-quality observation well program
(Julian Soren, w, Mineola)

Supplemental recharge by storm basins (D. A. Aronson,
w, Mineola)

Water resources, South Fork, Long Island (D. E. Vaupel,
w, Mineola)

North Carolina (w, Raleigh):

Ground water:
Automatic data processing program (C. C. Daniel)
Springs, Blue Ridge Parkway (C. C. Daniel)
Wilson County (M. D. Winner)
Hydrology of Albemarle—Pamlico area (R. C. Heath)
Northeastern part of State (H. B. Wilder)
Public water supplies (N. M. Jackson)
Surface water:
Evaporation, Hyco Lake (G. L. Giese)
Hydrology of estuaries (H. B. Wilder)
Low-flow and water-availability studies (H. G. Hinson)
Requests for data (H. G. Hinson)
Time-of-travel studies (W. G. Stamper)

North Dakota (w, Bismarck, except as noted otherwise):

Ground water:
Billings-Golden Valley Slope (M. G. Croft)

358

Water resources—Continued
States and territories—Continued
North Dakota (w, Bismarck, except as noted otherwise)—
Continued
Ground water—Continued
Dickey-Lamoure (J. S. Downey)
Dunn County (R. L. Klausing)
Grant and Sioux Counties (P. G. Randich)
Hydrologic changes due to mining (O. A. Crosby)
Morton County (P. G. Randich)
Northern Great Plains (M. G. Croft)
Ramsey County (R. D. Hutchinson, w, Grand Forks)
Ransom-Sargent (C. A. Armstrong)
Special investigations (Q. F. Paulson)
National eutrophication survey (0. A. Crosby)
Ohio (w, Columbus):
Big Island aquifer test (S. E. Norris)
Ground water:
Regional flow systems (R. E. Fidler)
Southeastern part, principal aquifers (A. C. Sedan)
Water inventory, hydrologic studies (D. D. Knochenmus)
Oklahoma (w, Oklahoma City):
Ground water:
Antlers sand (D. L. Hart, Jr.)
Edmond-Guthrie area (J. E. Carr)
Vamoosa Formation (J. J. D’Lugosz)
National eutrophication survey (W. B. Mills)
Requests, special investigations (J. H. Irwin)
Oregon (w, Portland):
Ground water:
Coos Bay, dune aquifers (J. H. Robison)
Drain-Yoncalla area (J. H. Robison)
Harrisburg-Halsey (F. J. Frank)
Lincoln County coast (F. J. Frank)
Near Winston (D. D. Harris)
Newberg area (A. R. Leonard)
Surface water:
National eutrophication survey (Antonius Laenen)
Oregon lakes and reservoirs (R. B. Sanderson)
Warm Springs Reservation (J. H. Robison)
Umatilla Reservation water (J. B. Gonthier)
Pennsylvania (w, Harrisburg, except as noted otherwise):
Geohydrology of Berks County (C. R. Wood)
Geology and groundwater resources of Monroe County
(L. D. Carswell, w, Philadelphia)
Ground water:
Chester County (L. J. McGreevy, w, West Chester)
Cumberland Valley (A. E. Becher)
Ground-water resources of the Williamsport area (0. B.
Lloyd)
Summary report of the ground-water resources of each
county in Pennsylvania (C. R. Wood)
Low flow, Susquehanna River basin (J. T. Armbruster)
Quality of water:
Highway construction effects on streams (J. F.
Truhlar, Jr.)
Sediment from highway construction (J. F.
Truhlar, Jr.)
Steamflow characteristics (L. V. Page)
Western Pennsylvania (H. E. Koester)

GEOLOGICAL SURVEY RESEARCH 1975

Water resources—Continued
States and territories-Continued
Puerto Rico (w, San Juan):
Contingent requests (D. G. Jordan)
Ground water, North Coast model (J. E. Heisel)
Hydrologic systems modeling (M. A. Lopez)
Maunabo Valley (D. G. Adolphson)
Quality of water, hydrologic effects of copper mining
(L. J. Mansue)
Surface water, floods investigation program (W. J. Haire)
South Carolina (w, Columbia):
Cooper River re-diversion (C. A. Spiers)
Reconnaissance of estuaries (F. A. Johnson)
Short-term planning studies (P. W. Johnson)
South Dakota (w, Huron, except as noted otherwise):
Brown County (N. C. Koch)
Cheyenne and Standing Rock Indian Reservations (L. W.
Howells)
Clark County (L. J. Hamilton)
Deuel and Hamlin Counties (J. Kume, w, Vermillion)
Douglas and Charles Mix Counties (J. Kume, w,
Vermillion)
Ground water:
Eastern part of State, basic research (E. F. LeRoux)
Hand and Hyde Counties (N. C. Koch)
McPherson, Edmunds, and Faulk Counties (L. J.
Hamilton)
Mineral and water resources (J. E. Powell)
National eutrophication survey (0. J. Larimer)
Tennessee (w, Nashville, except as noted otherwise):
Caney Fork, Upper (D. R. Rima)
Duck River basin, upper (C. R. Burchett)
Flow characteristics (V. J. May)
Hydrogeology of linear features (D. R. Rima)
Memphis area (J. H. Criner, Jr.)
Miscellaneous data services (V. J. May)
National eutrophication survey (V. J. May)
Terrace-deposits study (W. S. Parks, w, Memphis)
Water for Murfreesboro (D. R. Rima)
Texas (w, Austin, except as noted otherwise):
Ground water: -
Artificial recharge research (R. F. Brown, w, Lubbock)
El Paso (W. R. Meyer, w, El Paso)
Galveston County continuing quantitative studies
(R. K. Gabrysch, w, Houston)
Houston (R. K. Gabrysch, w, Houston)
Model study, Chicot and Evangeline aquifer (D. G.
Jorgensen, w, Houston)
Orange County (G. D. McAdoo, w, Houston)
Rio Grande environmental study (J. S. Gates, w, El
Paso)
Salt encroachment at Houston (D. G. Jorgensen, w,
Houston)
San Antonio (R. D. Reeves, w, San Antonio)
Hydrologic investigations:
Drainage-area determinations (P. H. Holland)
Limestone hydrology study (R. W. Maclay, w, San
Antonio)
National eutrophication survey (L. G. Stearns)
Quality of water, bays and estuaries (D. C. Hahl)

INVESTIGATIONS IN PROGRESS 359

Water resources—Continued
States and territories—Con tinued
Texas (w, Austin, except as noted otherwise)—Continued
Trust territory, water resources information (D. A. Davis, w,
Honolulu, Hawaii)
Utah (w, Salt Lake City, except as noted otherwise):
Altering Great Salt Lake (K. M. Waddell)
Environmental impacts (Donald Price)
Ground water:
Cedar City and Parawon (L. J. Bjorklund, w, Cedar
City)
Oil shale hydrology (F. K. Fields)
Reconnaissance, White Valley (J. C. Stephens)
Statewide ground-water conditions (J. C. Stephens)
National parks, monuments, and historical sites (C. T.
Sumsion)
Northern Uinta basin (J. W. Hood) .
Program enhancement (Theodore Arnow)
Quality of water:
Flaming Gorge Reservoir (E. L. Bolke)
Surface water, Duchesne River (J. C. Mundorff)
Surface water:
Canal-loss studies (R. W. Cruff)
Flood frequency and magnitude (F. K. Fields)
Inflow to Great Salt Lake (J. C. Mundorff)
Mined lands rehabilitation (G. W. Sandberg, w, Cedar
City)
National eutrophication survey (R. W. Cruff)
Vermont (w, Montpelier):
Ground water: ’
Barre-Montpelier area (A. L. Hodges, Jr.)
Mad River area (A. L. Hodges, Jr.)
Upper Winooski Basin (A. L. Hodges, Jr.)
White River junction (A. L. Hodges, Jr.)
Virginia (w, Richmond, except as noted otherwise):
Coastal plain studies (W. F. Lichtler)
Ground water:
Geohydrologic data (R. L. Wait)
Hydrology of Prince William Forest (G. A. Brown)
South of James River (0. J. Cosner)
Hydrologic monitoring, Fairfax (P. L. Soule, w, Fairfax)
National eutrophication survey (P. N. Walker)
Service work (R. L. Wait)
Surface water, project planning and public inquiries
(R. L. Wait)
Water quality, sediment transport in the Occoquan
watershed (W. D. Silver)
Washington (w, Tacoma):
Centralia strip mining and monitoring (J. S. Zogorski)
Ground water:
Long Beach (J. V. Tracy)
Movement of contaminants (J. V. Tracy)
Special hydrologic problems (B. L. Foxworthy)
Spokane Basin water resources (H. H. Tanaka)
Squaxin Indian Reservation (K. L. Walters)
Swinomish (K. L. Walters)
Test drilling (K. L. Walters)
Model simulation for water management (R. D. MacNish)
National eutrophication survey (P. J. Carpenter)
Real-time data collection (R. R. Adsit)

Water resources—Continued

States and territories—Continued
Washington (w, Tacoma)~Continued
Tulalip water resources (K. L. Walters)
Yakima Indian Reseri‘ration, water quality (M. O.
Fretwell)
West Virginia (w, Charleston, except as noted otherwise):
Coal River study (J. S. Bader)
Elk River basin study (G. R. Tarver)
Jefferson County study (W. A. Hobba, Jr., w,
Morgantown)
Quantitative mine-water studies (G. G. Wyrick)
Salt water in State (J. B. Foster)
Small drainage areas (G. S. Runner)
Studies for unforeseen needs (G. G. Wyrick)
Wisconsin (w, Madison):
Ground water:

Columbia County (C. A. Harr)

Jefferson County (G. E. Hendrickson)

St. Croix County (R. G. Borman)

Washington-Ozaukee Counties (H. L. Young)
Hatchery development (R. P. Novitzki)

Low flow of small streams (R. W. Devaul)
Menomonee River basin (M. G. Sherrill)
Quality of water:

Ground-water quality monitoring (C. A. Harr)

Menomonee River sediment study (S. M. Hindall)

Pine River basin (P. A. Kammerer, Jr.)

Washington County sediment study (S. M. Hindall)
Southeastern part of State, digital model (H. L. Young)
Statewide map series (R. W. Devaul)
Surface water:

Drainage areas (B. K. Holstrom)

Recreation reservoirs (W. A. Gebert)

Wyoming (w, Cheyenne):

Arikaree/alluvium, Dwyer Junction (G. C. Lines)
Arikaree Formation, Lusk (M. A. Crist)
Effluent monitor, national parks (E. R. Cox)
Green River Basin water supply (H. W. Lowham)
Ground water, Albin-Lagrange (W. B. Borchert)
Hanna Basin water resources (K. D. Peter)
National eutrophication survey (K. G. Polinoski)
Stream loss to Madison Limestone (F. C. Boner)
Water resources, Powder River Basin (M. E. Lowry)
Weston County (M. E. Lowry)

. Waterpower classification:

Alaska, Chakachamna Lake, study of potential powersite
(G. C. Giles, c, Tacoma, Wash.)
California (c, Sacramento):
Lower Trinity River, review of withdrawals (R. D.
Morgan)
Pit River, review of withdrawals (S. R. Osborne)
Smith River, review of withdrawals (R. D. Morgan)
Colorado, Dolores River Basin, review of withdrawals (G. A.
Lutz, c, D)
Oregon (c, Portland):
Clackamas River Basin, review of withdrawals (L. O.
Moe)
Nestucca River Basin, review of withdrawals (K. J.
St. Mary)

360

Waterpower classification—Continued
Oregon (c, Portland)—Continued
North Umpqua River, review of withdrawals (J. L.
Colbert)
South Umpqua River, review of withdrawals (J. L.
Colbert)
Washington (c, Tacoma):
Blanca Lake and Troublesome Creek pumped-storage site,
Skykomish River (J. B. Dugwyler, Jr.)
Columbia River, vicinity of developed Wells Project,
review of withdrawals (J. B. Dugwyler, Jr.)
Wood Plateau-Coyote Creek and John Day pool
pumped-storage site, Columbia River (J. B.
Dugwyler, Jr.)

GEOLOGICAL SURVEY RESEARCH 1975

Waterpower classification—Continued
Wyoming (c, D):
Greybull and Shoshone Rivers, review of withdrawals
(G. A. Lutz, c, D)
Wind River Basin, review of withdrawals (S. R. Osborne,
c, D)

Wilderness Program. See Primitive and Wilderness Areas under
Mineral and fuel resources-compilations and
topical studies, mineral-resources surveys.

Zeolites:

Bowie area, Arizona (L. H. Godwin, c, NC)
Southeastern California, Oregon, and Arizona (R. A.
Sheppard, D)
Zinc. See Lead, zinc, and silver.

SUBJECT INDEX

 

[Some discussions cover more than one page, but only the number of the first page is given. See also “Investigations in Progress” (p. 326)]

A

Aerotriangulation, topographic applica-
tions _____________________

Age determinations. See Geochronologyh

as well as under individual
States.

Alabama, acid mine drainage _________
cooperating agencies _____ _
engineering hydrology -- _
hydrology ______________ -
quality of water __ __
remote-sensing studies _
subsidence
USGS offices .....................

Alaska, Alaska Mineral Resource Assess-

ment Program (AMRAP) _
alluvial materials
artificial recharge
benthic invertebrates, sampling tech-

 
 
 
 

 

 
 
 

 

    
 

Page

287

88
310
89
245
88
245
226
323

 

niques
coal __________________
cooperating agencies _____________ 310
copper __________________________ 68
copper-molybdenum miii‘eralization _ 67
erosion surveys __________ + _______ 109
gas-saturation studies _ _ 109
geochronology __. _ 69, 70
geologic mapping __. - 77
geophysical studies _______________ 129
glaciology ........................ 1 70
gold ______________________________ 65
gravity studies ___________________ 63
ground water .................... 109
heavy minerals ___________________ 23
hydrology _______ 109
igneous studies __ 68
limnology ____________ 109
marine sedimentation __________ 130, 132
metamorphism __________ 64, 66, 67, 68, 71
palynology _______________________ 23
petrography ______________________ 69
plutonism ________________________ 68, 71
potamology _______________________ ~19 0
remote-sensing studies _______ 245
stratigraphy ______ __ 64, 67, 70, 71
structural geology _ 65, 66, 69, 129
tectonics _________________________ 70
thorium __________________________ 65
uranium _________________________ 65
urban hydrology __________ ~ ________ 1 18
USGS ofiices __________ 319, 321, 322, 323
vertebrate fossils _________________ 67
volcanism ________________________ 67
waste disposal, hydrologic effects in
urban areas .............. 120
Alunite ______________________________ 9
Antarctica, environmental studies __-.. 272
geochronology ____________________ 273
paleobotany ______________________ 272
paleoclimates ..................... 161
reversed magnetic polarity in lavas 142
technical assistance 272
topographic mapping 282

 

 

  

 

 
 

Page
Antillean arc, modern uplift _ 126
Antimony, analysis of ________________ 16
Appalachian Highlands and Coastal
Plains, results of geologic
investigations ____________ 39
Applied geophysics techniques _________ 145
Apollo 1'7 mission ____________________ 230
Aquifers, geophysical methods ________ 180
model studies _____________________ 179
See also Ground water, as
well as under individual
States.
Aa'eal mineral‘ appraisal ______________ 6
Argentina, technical assistance ________ 265
Arizona, aquifer studies _-____-_____-__ 110
cooperating agencies _____________ 310
copper ___________________________ 6
evapotranspiration 187
fluid inclusions ________ 5
ground water -___ 110
land-use mapping 249
magnetism _______ 142
mineralization ____________________ 5
plant ecology ____________________ 192
plutonism _..________; _____________ 5
remote-sensing studies _________ 244,249
stocks and metal deposits _________ 5
structural geology ________________ 53
subsidence ________________ 227
USGS offices ___________ _ 319, 321, 323
vegetation changes, effect on runoff
and sediment yield _______ 109
volcanism ________________________ 31
Arkansas, aquifer studies _____________ 97
cooperating agencies _____________ 310

geologic mapping
paleontology
USGS ofiices ______
waste assimilation
water, use in irrigation __________
Astrogeology, results of investigations _
Australia, Berridale batholith _________
land-system mapping _____________
remote-sensing studies ____________

Basemetal deposits ___________________
Basin and Range Province, results of
geologic investigations ___

Beaufort Sea, sea-ice studies __________
Bering Sea, geophysical studies _______
marine sedimentation ____________

U.S.-U.S.S.R. joint experiment _-_-

Bolivia, technical assistance __________
Brazil, technical assistance ____________
USGS offices _____________________

Caldera studies ______________________
California, artificial recharge _________
benthic invertebrates, artificial sub-
strates _________ ~_ _________

  

13

52
130
130
131
195
265
265
324

153
112

 

 

 
 

   
 

    

  

Page
California—Continued
chemistry of water __ 184
cooperating agencies 310
environmental geology, coastal ____ 211
environmental studies, coastal ____ 128
erosion __________________________ 183
estuarine hydrology _______________ 136
flood-frequency analysis __________ 217
flood-risk studies _________________ 219
geochemistry _____ _ _ 58
geochronology _____________ -- 58, 153
geologic mapping, submarine _ __ 127
geology __________________________ 112
geomorphology ___________________ 60
geophysical studies _______________ 56
geothermal studies __________ 31, 33, 141
gravity map, aid in ground-water
exploration _______________ 112
gravity studies ____________________ 60
ground movement, geothermal areas 33
ground water ________ 110, 111, 112, 181
heat flow __________ ;. _____________ 140
hydrology ________________________ 112
isotope studies ___________________ 111
landslides ________________________ 58
liquefaction map _________________ 209
paleoclimates ____________________ 162
paleontology __ ___ 175
petrology ___ _ 155, 157
plutonism _____________ 155, 156
quality of water ____________ 111, 184, 220
remote-sensing studies _________ 238, 244
San Andreas fault ________________ 59
sedimentology ____________________ 168
seismic studies ____________ 202, 204, 205
shelf basins ______________________ 128
soil engineering __ ..... 208
stratigraphy ______ __ 23, 57, 58
structural geology ______ 23, 55, 57, 58, 61
Structure and metamorphism, The
Geysers steam field _______ 57
subsidence ______________________ 60, 227
tectonics _______________________ 128, 153
urban geology ____________________ 209
urban hydrology __________________ 111
USGS ofiices ______ 318, 319, 321, 322, 323
volcanism '
volcano hazards
Calorimetric studies __________________ 148
Caribbean region, tectonic mapping -- 126
Cartography _______________ 289, 290, 291, 292

Cenozoic of the United States. results

of investigations _________ 175

Central Atlantic Regional Ecological

Test Site (CARETS)

 

project ______________ 249
Central Laboratory System ___________ 123.
Central region and Great Plains, results

of geologic investigations -_ 42
Chemistry, analytical __________ 195, 196. 197
Chukchi Sea, geomorphology .......... 131

361

362

 
  

  
  
   

  
  

  
   

 

  

 

 
 

Page
Coal. bibliography ____________________ 20
geochemical survey, Western re-
gions ____________________ 224
gravity studies ........ -_ 146
northern Great Plains _ _ 19
Powder River Basin ______________ 29
relation to tectonics ______________ 20
resources _________________________ 19
Coastal hydrology __________________ 134, 135
Colombia, technical assistance ________ 266
USGS oflices _____________________ 325
Colorado, artificial recharge __ __ 98
caldera collapse breccia _ __ 153
cooperating agencies -_-- -_ 311
engineering geology ______________ 209
engineering hydrology ____________ 97, 99
geochemistry _____________________ 16
geochronology _______________ 50, 153, 156
geochronometry __________________ 162
geologic mapping ________________ 76
geothermal studies __ 32
gravity studies ..... ---_ 146
ground water __ __ 97, 98, 100
hot springs _______________________ 32
irrigation ________________________ 98
land-use planning ________________ 209
lignite resources __________________ 20
magmatism ________________ 154
oil shale _______ 27
ore deposits ___ ___ 16
paleontology - 173, 175
petroleum ___ ______ 24
plutonism __________________ 49, 156, 160
quality of water ______________ 97, 98, 221
remote-sensing studies ___________ 242
sedimentology ____________________ 169
soil mapping _____________________ 209
stratigraphy ______________ 26, 46, 47, 153
structural geology _--_ 7, 153, 156
subsidence ________________________ 3, 146
thorite ___________________________ 30
thorium __________________________ 30
traceelement studies ______________ 154
uranium _________________________ 28, 29
uranium-thorium fractionation _ - _ _ 154
urban geology ____________________ 209
urban hydrology __________________ 209
USGS offices __ 318, 319, 320, 321, 322, 323
volcanism ______________________ 153, 154
water resources __________________ 98
water-supply studies ______________ 97, 98
Columbia plateau ..................... 152
Computer technology _______________ 293, 294
CRIB ............................ 17
environmental planning _ _ 210
GRASP ________________ _ 17
hydrologic problems _ -_ 194
MIDAP __________________________ 127
modeling __________________ 142, 143, 147
QSCAN __________________________ 159
SAMPLE ________________________ 159
USCOAL ______________ l7
water-quality evaluation __ 223
Connecticut, aquifer studies __ 81
cataclastic deformation _ 35
cooperating agencies --__ 312
floods ____________________________ 217
glacial geology ___________________ 38
r'ecessional moraines ______________ 37
structural geology ________________ 34, 38
USGS offices _______ _ 321, 323
weathering ________________ _ 38
Conodonts, as geothermometers _ _ 40
color alteration __________________ 39
Continental margin, Alaska-Antarctic -_ 129
Atlantic _________________________ 125
Gulf of Mexico and Caribbean _____ 126

 

SUBJECT INDEX

Page
Continental margin—Continued
Pacific ___________________________ 127
results of investigations __________ 125
Costa Rica, technical assistance ______ 266
Council of State Governments Task
Force ____________________ 252
Crater investigations ______________ 231,232
Crystal chemistry, results of investiga-
tions _____________________ 149
D
Deep Sea Drilling Program __________ 132
Delaware, cooperating agencies _______ 312
hydrology ________________________ 247
remote-sensing studies ____________ 247
USGS offices _____________________ 323
District of Columbia, cooperating
agencies _________________ 312
gravity studies ___________________ 42
USGS oflices ______ 318, 319. 320, 322, 323
E
Earthquake Information Bulletin ___. 296,297
Earthquake studies _____________ 199, 200, 201
Earth Resources Satellite (ERS)
systems __________________ 237
Economic geology ___________________ 3, 6, 11
See also under individual
States.
Ecuador, biostratigraphy, deep sea _ __ 133
Energy resources of the Earth _______ .. 23
Engineering geology, results of
investigations ______ 206, 207, 208
Environmental geochemistry __________ 224
Environmental geology ____________ 210,211

Environmental studies, Environmental
Impact Analysis program 256, 257

 
 

 

   

   
 

LUDA data ______________________ 255
mining studies __ _ 212
EROS, Data Center ________ _ 294
materials, how to obtain _________ 297
program _________________________ 237
Estuarine hydrology, Atlantic coast ___ 134
Gulf coast ________________________ 135
Pacific coast _____________ 135
results of investigations 134
Evapotranspiration, results of investiga-
tions ___________________ 187, 188
F
Far East. See individual countries listed
on p. 265.
Faults. See Structural geology under
individual States.
Finland, geochemistry ________________ 156
Flood-frequency studies, results of in-
vestigations ___- _ 217
Flood mapping ____________ - 219
remote-sensing studies ____________ 240
urban areas ______________________ 220
Floods, National Program for Managing
Flood Losses _____________ 220
outstanding ______________________ 217
results of investigations __________ 216
Florida, aquifer studies _______ 89, 90, 91, 186
artificial recharge -__ _ 92, 178
chemistry of water _. _ 184
coastal hydrology ________________ 89
cooperating agencies ______________ 312
environmental studies ____________ 25
estuarine hydrology ______________ 135
evapohranspiration _______________ 187

flood mapping ___________________ 219

 

 

  
  

  

   

 

Page

Florida —Continued
flood profiles _____________________ 217
ground water ____________________ 89
hydrology ________________________ 246
land use _________________________ 246
quality of water ______ 90, 91, 92, 221, 222
remote-sensing studies __ 246
saline water, intrusion ______ 91,116,221
storm runoff, urban areas ________ 120
urban hydrology __________________ 118
USGS oflices ___________________ 321, 323
waste disposal _____________ 121, 145, 222
water management _______________ 92
water resources __________________ 90, 91
water-supply studies __ _____ 92

Fluid inclusions _________ ___ 5,148,233

Fluorspar ____________________________ 10

Fuels, mineral, results of investigations 1

See also Coal, Petroleum, as
well as under individual
States.
G
Geochemical and geoehronological
studies, results of ________ 54
Geochemical studies, Western coal re-
gions ____________________ 224
Geochemistry ______________ 1, 6, 15, 148, 158
computer simulation of sampling
problems _________________ 159
experimental and theoretical ______ 147
health ____________________________ 225
isotope, results of investigations __ 159
new methods _____________________ 16
nuclear, results of investigations __ 159
sediments ________________________ 157
urban areas ______________________ 225
water ___________________________ 157
Geochronometxry ____________________ 162, 163
See also under individual
States.

Geodetic data management 285

Geographic studies, results of ________ 253

Geologic mapping, intermediate-scale __ 73
large regions ____________________ 76
large-scale _______________________ 73
Mars ____________________________ 228
New England ____________________ 34

Geomagnetic studies _______ 143, 144, 146, 147

Geophysics, experimental _____________ 140

See also under individual
States.

Georgia, aquifer studies .............. 186
cooperating agencies _____________ 312
ground water ____________________ 92
LUDA, experimental demonstration

projects 254
quality of water _____________ _ 93, 186
stream-temperature characteristics _ 222
USGS oflices _____________________ 323
Geothermal resources, results of investi-
gations __________________ 30, 51
See also under individual
States.
Geothermal studies, brine ____________ 33
calculation of deep reservoir tem-
peratures - - 166
infrared surveys _____ 33
Long Valley caldera 140
modeling _________________________ 166
remote-sensing studies ____________ 244
Ireservoir engineering _____________ 3
structural control of steam resources 167
Geothermal systems, results of investiga-
tions _____________________ 164
Germany, crater investigations ________ 232

Page
Glaciology, numerical methods ........ 171
remote-sensing studies ____________ 240
results of investigations __________ 170
Global tectonic theory, relation to metal-
logeny ___________________ 1
Gold, Carlin-type deposits ____________ 4
geochemical cycle ________________ 15
See also under individual
States.
Gravel _______________________________ 40
Gravity studies. See under individual
States.
Ground movement, geothermal areas _- 33
Ground water, dissolved gases ________ 158
multistate studies ________________ 109
remote-sensing studies ____________ 240

See also Aquifers, as well

as under individual States.
Ground-water hydrology, results of in-

vestigations ______________ 177
Ground-water-surface-water relation-

ship, results of investiga-

tions _____________________ 185
See also under individual
States.
Gulf of Mexico, salt structures and
petroleum migration ______ 126
H

 
    
 

 

 

  

 

Hawaii, cooperating agencies _ 312
geochemistry _____________ 157
geochronology __ __________ 151
petrology ___________________ 154
sediment transport ________________ 112
structural geology ________________ 150
tectonics _______________________ 147, 152
thermoluminescence dating

technique
USGS offices ___-
volcanology _____
water resources __________________

Iieat flow __________________________ 140,141

Heavy minerals ______________________ 23

Helium, determination in soils ........ 16
energy resource exploration ______ 25

Hot springs __________________________ 32

Hydrocarbons ____________________ 24

Hydrologic Bench-Mark Network _ 122

Hydrology, carbonate-rock terranes ___ 178
coastal ________________________ 134, 135
computer programs _______________ 194
estuarine _________________________ 134
ground water ____________________ 177
new instruments and techniques __ 192
relation to radioactive wastes _-_- 214
remote-sensing studies ________ __ 246
surface ‘water __________ ___- 181

See also under individual
States.
Hydrothermal alteration, chemical
characteristics ___________ 3
l

Iceland, remote-sensing studies ________ 240

Idaho, cooperating agencies
geochemistry ____________
geothermal studies ____________
ground .water ____________________
ground-water—surface—water

relationship ______________ 113
heat flow ___________ 141
igneous studies _-_ 48
mineral resources 8
ore deposits ______________________ 15
palynology _______________________ 175

 

 

SUBJECT INDEX

 
 
  
  
 

   

~ Page
Idaho—Continued
remote-sensing studies ____________ 239
stratigraphy _____________________ 46
structural geology ..... _ 7, 50, 52
subsidence _____________ __ 227
tm ___________ _-_ 12
USGS offices - ______ 320,323
volcanism ________________________ 49
volcano-tectonic depression ________ 48
water resources __________________ 113
Igneous studies, results of ____________ 48
ultramafic inclusions _____________ 155
Illinois, cooperating agencies -- _ 313
floods ____________________ _ 218
ore bodies ________ _ 1
quality of water __ ________ 223
USGS ofiices ___________________ 323
India, crater investigations ___________ 231
Indiana, cooperating agencies ________ 313
quality of water __________________ 81
surface water ____________________ 185
USGS offices ______________________ 323
Indonesia, geochronology _____________ 163
plate tectonics ____________________ 267
remote-sensing studies ____________ 267
technical assistance _____ - 266
topographic mapping -_ _ 267
USGS oflices ____________ _ 325
Inertial surveying ____________________ 284
Infrared surveys, geothermal systems -_ 33

International cooperation, Earth sciences 258
International Hydrological Decade, 1965—

1974 _____________________ 123

Iowa, cooperating agencies _____ __ 313

floods _________________ -_ 218

   
 

   
   
 
 

 
 
 

    

USGS oflices __________________ 323
Isotope tracer studies, results of ______ 159
J

Journal of Research of the US. Geologi-
cal Survey ____________ 296,297
K
Kansas, artificial recharge ____________ 178
cooperating agencies _____________ 313
floods ____________________________ 119
geologic mapping ________________ 45
ground water __________________ 100, 101
quality of water _________________ 223
sedimentology ___- __ 168
USGS offices _______ -_ 323
water management __ __ 101
water-supply studies _____________ 100
zinc ______________________________ 2
Kentucky, coal ___________ 42
cooperating agencies _____ 313
geologic mapping ________________ 42
land-use planning ________________ 43
lithostratigraphy and deposition _ _ 42
palynology _______________________ 174
quality of water - 93
plant ecology ___________ -_ 192
stream-aquifer modeling ___ 185
USGS offices __________________ 321,323
wells _____________________________ 93
Kenya, ground water _-__ 241
remote-sensing studies ____________ 241
technical assistance ______________ 267
USGS oflices _____________________ 325
Known Geologic Structures (KGS) ___ 137
Known Geothermal Resources Areas
(KGRA) _________________ ’ 137

 

363

  

   
  

 
 

 

Page
L
LANDSAT imagery,
uses of ___- 237, 238, 239, 240, 241,
242, 243, 244, 246, 247,
248, 249
Landslides ___________________________ 40
Land subsidence. See Subsidence.
Land-Use and Data Analysis (LUDA)
program _______________ 251, 253
environmental impact ____________ 255
geographic information system de-
velopment ________________ 256
land-use data projects ____________ 255
Land-use and environmental impact, re-
sults of investigations ___- 252
Land-use—land-cover classification sys-
tem ______________________ 255
Land-use planning, cartographic tech-
niques ‘_ __________________ 289
See also under individual
States.
Land-use studies, remote sensing _____ 246
Lead ________________________________ 160
See also under individual
States.
Lead—isotope analysis _________________ 147
Lead-zinc ores __ ____________ 3
Limnology __________________________ 188, 189
See also under individual
States.
Lithium _____________________________ 11, 12
Louisiana, aquifer studies ___________ 101, 102
coastal hydrology _____ -_ 135
cooperating agencies __ __- 313
ground water ____________ - 101, 102
LUDA map and data uses ________ 254
quality of water ________________ 101, 102
subsidence _______________________ 226
surface water ___________________ 182
unstable sediments _______________ 170
USGS offices ______________ 319, 320, 323
water-supply studies ______ 102
Luminescence studies ___________ __ 242
Lunar studies, Apollo 17 results _ __ 230
basins __ 229
craters ___________________________ 231
results of investigations __________ 229
Lunar samples, chemical composition __ 236
geochronology ____________________ 236
glasses and fines _________________ 235
petrology ______________ 233
results of investigations 233

 

Magmas, Yellowstone National Park _- 164
Magmatic processes, results of investiga-

tions ____________________ 155
Magnetics _____________________ 141, 142, 145
Maine, cooperating agencies __________ 313

  
 
  

environmental studies ________ _ 1 0

 
 
 

plutonism ____________ - 37
USGS offices _______________ 323
Malaysia, petrology __________________ 155
Mapping, accomplishments ___________ 276
Antarctica _______________________ 282
field surveys _____________________ 284
intermediate-scale ________________ 281
international cooperation - - 284
national parks ___ _ 279
orthophotoquads ___________ _ _ 280
quadrangle map coverage ________ 276
revision and maintenance ________ 276
scale 1:250,000 ___________________ 276
small-scale _______________________ 280

special surveys and investigations __ 286

364

 

 

 

 

Page
Mapping—Continued
State base maps _________________ 276
See also Cartography,
Photogrammetry, Topogra-
phic mapping, as well as
under individual States.
Mapping program, national __________ 274
Marine geology, equatorial Pacific ___- 133
results of investigations __________ 125
Marine terraces, uranium-series dating _ 163
Mars, geologic mapping _ 228
interpretive studies ______________ 228
mineralogical investigations ______ 233
topographic mapping ____________ 228
Viking support __________________ 228
Maryland, cooperating agencies -_-__-_' 313
environmental geology ___________ 210
estuarine hydrology ______________ 134
ground water _ 82
hydrology ________________________ 247
remote-sensing studies ___________ 247
urban hydrology __________________ 119
USGS offices _____________________ 323
Massachusetts, aquifer studies ________ 82
cooperating agencies _____________ 313
floods __________________________ 218,219
freshwater-saltwater interface _ _ _ _ 115
geochronology ____________________ 35
glacial geology ___________________ 38
glaciomarine deposits ____________ 39
ground water ____________________ 82,83
lithostratigraphy _________________ 36
quality of water __________________ 82
stratigraphy _______ 39
structural geology __-.. ____________ 36,37
USGS offices ___________________ 321, 324
volcanism ‘ 37
water resources __________________ 82, 83
water-supply studies _____________ 83
Mercury _____________________________ 229
Metallogeny __________________________ 1
Metamorphic rocks, northern Sierra
Nevada __________________ 56
Metamorphic rocks and processes, re-
sults of investigations _--_ 156
Metamorphism, “burial” ______________ 157
contact __________________________ 40
Mesozoic of the United States, results
of investigations ________ 174
Mexico, technical assistance __________ 267
topographic mapping _____________ 284
Michigan, cooperating agencies _______ 313
economic geology _________________ 6
environmental studies ___. _________ 83
ground water ____________________ 84
iron ______________________________ 10
paleomagnetism __________________ 43
preglacial topography ____________ 43
quality of water __________________ 83
structural geology ________________ 44
USGS oflices ___________ ‘ _________ 3 24
volcanism ________________________ 43
Mineral commodities, appraisal of ___- 9
Mineral identification, index method __ 149
Mineral investigations, primitive areas __ 7
study areas ______________________ 7
wilderness areas __________________ 7
Mineral lands, classification and evalua-
tion _____________________ 137
Mineral leasing, supervision __________ 138
Mineral occurrences, geology of ______ 1
Mineral studies, results of investigations 149
Mineralogic studies, results of ________ 149
Mineralogy, alteration in mafic and
ultramafic rOCAS __________ 148
crystal chemistry ________________ 149

 

SUBJECT INDEX

  
        
   
   

 

 
   
  

   

    
   
      

 
 
 

Page

Mineralogy—Continued
Na-K distribution, hornblende and

malt _____________________ 148
See also under individual
States.

Mineral resources, exploration ________ 15
remote-sensing studies ________ _ 243
results of investigations ___- _ 1

Minerals attaché program _____ _ 264

Mining, environmental problems _ 212

Minnesota, aquifer studies ______ _ 85
cooperating agencies ____ _ 313
engineering hydrology _ __ 83
floods ________________ 218, 219
ground water _______ _ 84,85
quality of water _______ _ 223
remote-sensing studies _ 246
sedimentology __________ _ 168
urban hydrology _ 119
USGS offices _____ _ 324
volcanism _______ __ 44
water resources ___- ___ 85, 246
water-supply studies __________ 84, 85, 122

Mississippi, chemistry of water _______ 183
cooperating agencies _ 314
remote-sensing studies 244
USGS oflices _______________ 320, 321, 324

Missouri, birth defects in swine _______ 225
computer technology - 294
cooperating agencies _ _________ 314
flood mapping _ __ ________ 289
floods ____________________________ 218
ground-water—surface-water

relationship _______________ 186
USGS offices __________ 319, 320, 322, 324

Montana, aquifer studies _____________ 103
coal _________________ 19
cooperating agencies __ ________ 314
ground water _ 103
hot springs ___- _____ 51
igneous studies _____ 48
natural gases ________ 24
platinum ____________________ 12
remote-sensing studies _ ______ 238, 242
structural geology __ __________ 50
USGS offices ______ ___- 320, 324
water resources __________________ 103

N
National Atlas ______________________ 281
National Cartographic Information Cen-
ter (NCIC) _____________ 275
National Stream Quality Accounting
Network _________________ 122

National Technical Information Service 297

Natural gases, origins of _____________ 24

Natural-resource management, Federal

and Indian lands ________ 137

Near East. See individual countries

listed on p. 265.

Nebraska, cooperating agencies ______ 314
geologic mapping ________________ 45
remote-sensing studies ___________ 239
USGS offices ____________________ 324
water management _______________ 103

Nepal, technical assistance ___________ 268

Nevada, cooperating agencies ________ 314
crater investigations _____________ 232
economic geology ________ 52
floods _______________________ 217
fossil thermal gradients. 161
geochronology _______________ 54, 55
geologic hazards __ 53
geologic mapping ________________ 76

 

    

Page
Nevada—Continued
igneous studies ___________________ 4
ore-forming solutions ____________ 161
paleoclimates ____________________ 162
paleontology ______________________ 172
petroleum ________________________ 22
quality of water __________________ 223
remote—sensing studies ____________ 244
sedimentary rocks ________________ 53
seismic studies ___________________ 206
stratigraphy ___________________ 4, 54, 55
turquoise deposits ________________ 4
USGS offices ______________________ 324
volcanism ____________ '. ___________ 5 3
water resources __________________ 114
water-supply studies ______________ 114
New Britain, island-arc magmas ______ 159
Newfoundland, paleontology __________ 172
New Hampshire, cooperating agencies _ 314
USGS offices _____________________ 324
New Jersey, aquifer studies __________ 86
chemistry of water _______________ 183
cooperating agencies _____________ 314
floods ____________________________ 120
ground water, saline _____________ 86
landslides ________________________ 40
quality of water _______________ 223,224
USGS offices ____________________ 324
New Mexico, cooperating agencies __-_ 314
floods ____________________________ 219
geochemical anomalies ___________ 54
geothermal studies _______________ 104
gold ______________ L _____________ 2
mineral resources ________________ 6
Mogollon mining district, geologic
reappraisal ______________ 2
stratigraphy _____________________ 47
structural geology ________________ 51
USGS ofl'ices _______________ 320, 321, 324
zeolites __________________________ 2
New York, aquifer studies ____________ 86
cooperating agencies _____________ 314
paleontology ______________________ 172
quality of water ________________ 184, 224
sedimentation, lacustrine and
marine __________________ 39
storm runoff _____________________ 120
USGS offices _____________________ 324
waste disposal __________________ 121, 180
water~supply studies ______________ 86
North America, coral zoogeography -___ 173
metallogenic map ________________ 76
NorthoCarolina, aquifer studies _______ 94
cooperating agencies ______________ 315
estuarine hydrology ______________ 93
evaporation ______________________ 187
floods ____________________________ 218
ground water ____________________ 94
paleontology ___________________ 176, 177
resistivity studies _________________ 145
sedimentology ____________________ 169
structural geology ________________ 1
tungsten _________________________ 1
USGS offices _____________________ 324
North Dakota, aquifer studies ______ 104, 105
cooperating agencies _____________ 315
floods ____________________________ 218
geohydrology _____________________ 104
ground water ____________________ 104
USGS offices ______________________ 324
Nuclear energy, results of investigations 213
Nuclear explosions, underground ______ 213
Nuclear-fuels resources, results of in-
vestigations _- 27
Nuclear-power reactors _______ 216
Nuclear test-site studies _______________ 213

   
  
  
 
   
  
 
 
  
  

 

Page
0
Oflice of Minerals Exploration ________ 14
Discovery Loans Program ________ 14
Office of Water-Data Coordination ____ 116
Ohio, cooperating agencies ____________ 315
sedimentology ____________________ 167
USGS offices ___________________ 321, 324
Oil, reserves _________________________ 24
secondary recovery ________________ 26
Oil and gas resources, results of in-
vestigations ______________ 20
Oil shale, hydrology of oil-shale lands .- 99
resistivity ________________________ 145
results of investigations _________ 26,27
Oklahoma, cooperating agencies ______ 315
ground water ____________________ 105
USGS offices _______ _ 320, 324
Oman, technical assistance - 268
Ore ___________________________ _ 1
deposits, lead-isotope analysis 16
hydrothermal fluids _-- - 161
Oregon, base flow ________ _ 114
cooperating agencies _ _ 315
estuarine hydrology _ 136
geologic mapping _ _ 76
geomorphology - 129
geothermal studies _- __ 31
ground water ____________________ 114
inflow streams ___________________ 115
metamorphism ___________________ 61
remote-sensing studies ____________ 239
sedimentology ____________________ 168
structural geology ________________ 61
USGS offices ____________________ 320, 324
zeolites ___________________________ 13
Orthophotos, experimental products ___ 292
image quality ____________________ 291
systems __________________________ 291
maps, large-scale ________________ 291
scan masks ______________________ 291
p
Pacific coast region, results of geologic
investigations ____________ 55
Pacific Ocean, marine geology ________ 133
Pakistan, technical assistance ________ 268
Paleogeography, crustal shortening esti-
mates ____________________ 21
Paleontology, bivalves, early Paleozoic __ 176
Bryozoa, Western United States __ 173
conodont alteration _______________ 173
foraminifers _____________________ 177
results of investigations __________ 171
See also Biostratigraphy,
Paleontology under indivi-
dual States.
Paleotectonic maps ___________________ 77
Paleozoic of the United States, results
of investigations _________ 172
Palynological studies __________________ 23
See also under individual
States.
Pan American Institute of Geography
and History (PAIGH) ___ 284
Pennsylvania, cooperating agencies ___ 315
floods ____________________________ 219
ground water ___________________ 87, 180
landslides ________________________ 210
limnology ________________________ 190
public water supplies ____________ 122
saline water _____________________ 87
subsidence _______________________ 212
USGS offices ___________________ 321, 324
Peru, biostratigraphy, deep sea ______ 133
technical assistance ______________ 269

 

SUBJECT INDEX

Petroleum, Appalachian basin __
Denver basin ______________ _
exploration problems _-
manganese as a detector ____
migration, Gulf of Mexico _
offshore Atlantic Ocean _____ _
sourCe beds ______________ _
source-rock studies ________________

See also under individual
States.

Petrology _____________________

results of investigations __________
See also under individual
States.

    
   
 

 

Page
20

24

25
25
126
20
22

22

- 155.161

Petrochemistry, results of investigations 154
Phosphate ___________________________ 11
See also under individual
States.
Photogrammetry _______________ 286, 287, 288
Physical properties data bank ________ 26
Planetary studies, results of investiga-
tions _____________________ 228
Plant ecology, results of investigations 192
See also under individual
States.
Plant physiology _____________________ 162
Plutonic rocks, results of investigations 155
Poland, technical assistance __________ 269
Potamology _________________________ 188, 189
Potentially mineralized areas, geologic
studies ___________________ 6
Project FAMOUS ____________________ 132
Publications program, USGS _________ 295
publications, USGS, how to
order __________________ 296, 297
USGS, number issued ____________ 296
USGS, out of print, how to obtain 296
Puerto Rico, flood-insurance studies __ 219
flood-prone areas _________________ 219
geochronology ____________________ 71
geomorphology ___________________ 127
igneous studies ___________________ 72
limnology _______________________ 189, 190
stratigraphy ______________________ 72
topographic mapping ____________ 289
USGS offices ___________________ 321, 324
water-supply studies ______________ 94
Q
Q-mode factor analysis _______________ 158
Quality of water, acid mine water,
neutralization ____________ 147
diversity indices __________________ 190
laboratory measurements __________ 185
modeling techniques ______________ 180
results of investigations __________ 220

Radioactive wastes, relation to hydro-

logic environment -_ 214,215,216

Regional geologic investigations, results
of ________________________
Remote-sensing studies, agricultural ap-
plications ________________

advanced techniques ______________
cartographic applications _________
digital image processing __________
ERTS—l, A New Window on Our
Planet ___________________
experiments by other Bureaus ____
fishery management ______________
flood mapping ____________________
geographic applications __________
geologic applications ______________
geothermal areas _________________

34

238
237
247
248

237
242’
242
240
249
243
244

 

365

 

     
   
  
 
 

 

  
 
  
  
 

Page
Remote-sensing studies~Continued
ground water ____________________ 240
hydrologic applications ___________ 245
image-marking technique _________ 248
Indian reservations ______________ 239
land use _________________________ 246
mapping, linear features __________ 237
mineral-resource studies __________ 243
near-infrared reflectance anomalies 244
oil-leak/spill studies ______________ 237
Raman signal intensities __________ 246
rangeland management ___________ 238
satellite-image maps _____________ 248
sea ice _________________________ 130, 194
snow studies _____________________ 247
soil studies ______, ________________ 243
surface-water mapping ___________ 240
TAPS corridor ___________________ 245
tectonics _________________________ 239
urban studies ____________________ 250
See also EROS, LANDSAT
imagery, as well as under
individual States.
Resistivity -__.__.-________________‘-_ 143, 145
Resource analysis, results of investiga-
tions ____________________ 17
Resource and _Land Investigations
(RALI) program ______ 252, 253
Resource data bases __________________ 17
Resource estimates ___________________ 17
Resource model studies _______________ 17
Rhode Island, cooperating agencies ___ 315
USGS offices _____________________ 324
Rock mechanics ______________________ 207
S
Saline water, deep brines 166
intrusion _________________________ 115
See also under individual
States.
Salt structures, Gulf of Mexico ________ 126
Saudi Arabia, economic geology ___ 269,270
gravity studies ._ _____ ___ 271
mineralization ____ ._ 270
structural geology __. _ 271
topographic mapping _ 284
USGS offices ....... _ 325
Sea ice, Beaufort Sea --__ __ 130
remote-sensing studies __ _ 194,195
results of investigations __________ 194
U.S.—U.S.S.R. joint Bering Sea ex-
periment _________________ 195
Sediment-control techniques 168
Sedimentology, results of investiga-
tions ______________ 167, 169, 170
Seismic studies, computer modeling ___ 142
See also under individual
States.
Silicates, crystal chemistry of ________ 149'
Skylab ________________________ 238,244,246
Slope-stability studies _________________ 206
Soil-moisture, remote-sensing studies __ 243
results of investigations __________ 186
South America, remote-sensing studies- 242
South Carolina, cooperating agencies __ 315
erosion _______________________ 170
estuarine hydrology ___ _______ 134
geochemical anomalies _______ 1
ground'water ________________ 95
palynology ___________ 41
quality of water ______ -_-_ 94, 95
remote-sensing studies __ ______ 244
USGS offices _______________ 324
vermiculite _________________ 10

366

 

Page

South Dakota, aquifer studies ______ 105,106
cooperating agencies 316
computer technology 294
mineral resources ____________ 18
remotesensing studies ____________ 239
USGS offices __________ 319, 321, 322. 324

Stable isotopes, results of investigations 160
Statistical geochemistry, results of in-

vestigations ______________ 1 58
Statistical petrology, results of investi-
gations __________________ 158

Stratigraphy, results of investigations _ 45, 46
See also under individual

 

Statcs.
Stratigraphic and structural studies.
results of ________________ 52
, See also under individual
States.
Structural and geophysical studies, re-
sults of __________________ 50
See also under individual
States. V
Subsidence ___________________________ 3, 225
Sec also under individual
States.
Surface water, remote-sensing studies- 240
temperature studies ______________ 185
See also under individual
States.
Surface—water hydrology, results of in-
vestigations ____________ 181, 182
See also under individual
States.
T
TAPS corridor, remote-sensing studies _ 245
Tectonics, eastern Mojave Desert ______ 61
See also under individual
States.
Tectonic mapping, Caribbean region __ 126
Tennessee, aquifer studies ____________ 95
cooperating agencies ______________ 316
environmental geology ____________ 210
floods ____________________________ 120
fluvial morphology ________________ 170
ground water _____________________ 95
streamflow, ksrst area ____________ 95
USGS ofl‘ices ___________________ 321, 324
water—supply studies _____________ 95
Terrestrial analogs and experimental
studies ___________________ 231
Texas, aquifer studies ________________ 106
artificial recharge ________________ 178
cooperating agencies ______________ 316
ground water ______________ 106, 107, 146
mercury 127
paleontology ______________________ 174
remote-sensing studies ____________ 238
subsidence _______________________ 226
uranium ________________________ 27, 146
USGS ofiices __________ 320, 321:322, 324
Thailand, remote-sensing studies ______ 271
technical assistance ______________ 271
USGS offices _____________________ 325
Thermochemistry, fossil-fuel formation 148
Thorium _____________________________ 160
See also under individual
States.
Tin __________________________________ 12
See also under individual
States.
Titanium resources ____.L _____________ 13
Topographic surveys and mapping _-._ 274
cartography ______________________ 289
coordination and requirements ____ 274

equipment improvements _________ 285

 

SUBJECT INDEX

 
  

Page

Topographic surveys and mapping—Continued
field surveys ______________________ 284
Mars ____________________________ 228
photogrammetry __________________ 286
research and development _____ 284

Transverse Ranges. geochronology - - - - 60

U

Ultramafic rocks, chemical differences __ 10

United States, geologic map __________ 76
seismotectonic map ______________ 77

Uranium ________________________ 29, 160, 162
analysis of water ________________ 30
byproduct of coal combustion _____ l9
depositional processes ____________ 27
exploration _______________________ 28
in pegmatites ____________________ 29
leaching _________________________ 27
Midnite mine ____________________ 29
Powder River Basin ______________ 29
remote-sensing studies ____________ 146
roll-type deposits ________________ 28

See also under individual
States.

Urban-area studies, geochemistry _____ 225
remote-sensing studies ____________ 250
water resources __________________ 118

See also under individual
States.

Urban geology, results of investigations 209
See also under individual

 
 
   
  

 
 

States.
Urban hydrology. See under individual
States.

Utah, aquifer studies _________________ 107
coal ______________________________ 20
cooperating agencies ______________ 316
geochronology ____________________ 55
geochronometry __________________ 4
hydrothermal alteration __________ 3
paleontology ______________________ 174
sedimentation ____________________ 21
stratigraphy _____________________ 54‘
USGS offices __________ 320, 321, 322, 324

V

Vermiculite, prospecting tools ________ 10

Vermont, cooperating agencies ________ 316
floods ____________________________ 219
USGS offices _____________________ 324

Virgin Islands, floods _________________ 217

Virginia, cooperating agencies _ _ 316
environmental geology _____ _ 210
geochronology __________ _ 41
hydrology ____________ _ 247
mineral resources -_-_ _ 13
quality of water ________ _ 87
remote-sensing studies _- _ 247
structural geology ______ _ 41
tectonics ___________________ 41
USGS offices ______ 318, 321, 322, 323, 324
water-supply studies _____________ 87

Volcanic rocks and processes, results of

investigations ____________ 149

Volcanism ____________________________ 149

See also under individual
States.
Volcano hazards _ 212
Volcanology __________________ _ 31, 152
See also under individual
States.

 

 

 

Page
W

Washington, bank storage ____________ 185
biostratigraphy ___________________ 176
cooperating agencies ______________ 316
estuarine hydrology .............. 135
geochronology _ 62
geomorphology 129
glacier hydrology _________________ 171
mineral resources _________________ 239
remote-sensing studies ____________ 289
runoff .' ___________________________ 183
seismic studies ___________________ 115
structural geology ________________ 62, 128
uranium _________________________ 29
USGS offices ______________ 321. 322, 324
volcano hazards __________________ 212

Washington, D.C. See District of

Columbia.
Waste disposal, hydrologic effects in
urban areas ______________ 120
logging of wells __________________ 145
Water, analysis of ____________________ 197
chemical, physical, and biological
characteristics ____________ 183
geochemistry, laboratory techniques 184
humic-acid derivatives, determina-
tion of _'_ ________________ 184
uses of ______ ‘ ___________________ 1 21, 122
See also Ground water, Hy-
drology, Surface Water, as
well as under individual
States.
Water-data storage system ____________ 117
Water-power classification. preservation
of reservoir sites ________ 138
_ Water quality, coordinate programs ___ 122
See also Quality of water.

Water-resource programs, special _____ 115

Water-resource studies, central region _ 96
northeastern region ______________ 80
remote-sensing studies 246
results of investigations _-___.' _____ 78
southeastern region _______________ 88
western region ___________________ 108

See also Ground water, Sur-
face water, Quality of
water, as well as under in-
dividual States.

West Virginia, acid mine drainage ____ 87
cooperating agencies _____________ 316
ground water ____________________ 88
paleontology ______________________ 174
quality of water __________________ 87
saltwater~freshwater mapping ____ 116
structural geology ________________ 42
USGS ofl'ices _____________________ 324

Wisconsin, artificial recharge _________ 178
cooperating agencies _____________ 316
copper ____________________________ 6
geochemical sampling _____________ 6
ground water ____________________ 186
quality of water __________________ 224
structural geology ________________ 44
USGS oflices _____________________ 324

Wyoming, aquifer studies ____________ 108
coal _________________________ 19, 29, 146
cooperating agencies ______________ 317
economic geology _________________ 3
engineering hydrology ____________ 108
erosion ___________________________ 169
flood mapping ____________________ 219
fluvial drainage patterns __________ 28
fossil fuels _______________________ 108
geochemical discriminant, sandstone 159
geochronology ____________________ 51
geochronometry ___________________ 162

  

    
 

 

   

    

   
 

Page

Wyoming—Continued
geologic mapping ________________ 77
geohydrology _____ ______________ 107
geothermal studies _ _ 166
hot springs _________ __ __ 165
hydrothermal explosion crater _ __ 165~
paleontology _ _ _ _' __________________ 17 5
petrology __________-.' _____________ 155
porosity studies __________________ 25
sedimentation ____________________ 21
stratigraphy _____________________ 46
Page

A
Abel, J. F. __________________________ 207
Ackerman, D. J. _____________________ 104
Ackerman, H. D. ___________________ 30,145
Adam, D. P. __________________________ 57
Adams, D. B. ________________________ 189
Addicott, W. 0. _ - 128, 176
Adkison, W. L. _ __ 23
Adolphson, D. G. -- _ 94
Ahlbrandt, T. S. ____________ _ 21
Albers, J. P. ________________ _ 264
Albert, N. R. D. _____________________ 239
Alexander, C. C. _____________________ 236
Algermissen, S. T. __________________ 201,264
Allcott, (3.11. ________________________ 267
Alldredge, L. R. _ 144
Alminas, H. V. __ 16,17
Alvord, D. C. ___- _ 42
Anderson, B. M. _____________________ 225
Anderson, G. S. ________________ 109, 118,177
Anderson, H. W., Jr. ________________ 85
Anderson, J. R. ______________________ 255
Anderson, R. E. ____________________ 270, 271
Anderson, T. W. _____________________ 187
Anderson, W. L. _ __ 147
Andrews, D. J. ..-_ __ 142
Andrews, G. W. __ 175
Annell, C. S. _________________________ 236
Anttila, P. W. _______________________ 167
Antweiler, J. C. III __________________ 2, 16
Armhrustmacher, T. J. ________________ 30
Armstrong, A. K. ____________ 54, 66, 68, 173
Armstrong, C. A. ____________________ 104
Arnal, R. E. ______ _ 23, 127
Aronson, D. A. __ _ 120
Arsenault, L. D. _ - 195
Arteaga, F. E. ______________________ 93,181
Arth, J. G‘. _________________________ 156, 159
Aruscavage, P. J. ____________________ 196
Ashley, R. P. ________________________ 52
Atwater, B. F. _ __ 58
Avanzino, R. J. _ _- 136, 184
Averett, R. C. __ _ 184
Averitt, Paul ________________________ 19
B

Bachman, G. O. _____________________ 51,216
Backer, M. I. ________________________ 119
Bada, J. L. __________________________ 57
Baedeeker, P. A. _____________________ 196
Bagdady, Abdulaziz - _______ 269

   
 
 

Bailey, E. H. __
Baird, A. K. ___ _______ 228
Bakun, W. H. ________________________ 199
Balding, G. 0. ________________________ 118

 

SUBJECT INDEX

 
  

Page
Wf’oming—Continued

" struc’tural geology ________________ 49

subterranean streams, dye-recovery
study ____________________ 108
surface water ___________ __ 183
surface-mine reclamation _-__ 213
uranium ______________________ 27, 28, 29
USGS offices _______________ 320, 321, 324

Y
Yemen Arab Republic, ground water __ 272

INVESTIGATOR INDEX

 

 

 
 
 

 

Page
Ballance, W. C. ______________________ 214
Bamber, E. W. ______________ 173
Banks, N. G. ________________ 5
Barker, Fred _______________________ 156, 161
Barker, 188
Barker, 209
Barnes, 63
Barnes, 124
Barnes, 206
Barnes, 130
Barnes, . . 197
Barosh, P. J. ________________________ 34
Barraclough, J. T. ___________________ 215
Barron, J. A. ________________________ 175
Bartsch-Winkler, S. R. ________________ 130
Batchelder, J. N. ________________ 46, 50, 161
Bateman, P. C. -___ _- 156, 263
Beall, R. M. _____ _ 122
Bearden, H. W. _ _ 221
Beeso‘n, M. H. ________________________ 154
Behrendt, J. C. ______________________ 125
Beightler. C. S. ______________________ 179~
Beikman, H. M. ______________________ 76
Bell, Henry III _______________________ 1
Bell, K. G. ___________________________ 35
Bennett, J. P. __ 94
Bennington, G. __ 253
Berdan, J. M. ___ 172
Berg, H. C. __________________________ 62,70
Berman, Sol ___, _____________________ 235, 236
Bertoldi, G. L. _______________________ 111
Best, R. G. __________________________ 239
Beverage, J. P. _______________________ 193
Beyer, L. A. __________________________ 23

Biesecker, J. E.
Billingsley, F. C.
Bingham, D. L.

   
 

 

Bird, M. L. __________________________

Bisdorf, R. J. ________________________ 143
Bisselle, Anthony _____________________ 253
Bjorklund, L. J. ______________________ 107
Blacet, P. M. ___________ 5,6
Blackford, M. E. ___ 199
Blake, M. 0., Jr. __-_ _ 13,56
Blanchard, H. E., Jr. _____________ 92
Boettcher, A. J. _____________________ 103
Boggess, D. H. _______________________ 221
Bohannon, R. G. _____________________ 12
Boner, F. C. _________________________ 107
Bonnet, C. W. 226
Booker, S. E. _-_ 184
Books, K. G. - 43
Boore, D. M. -_ 201
Booth, J. S. _________________________ 170
Borcherdt, R. D. ____________________ 201, 204
Borchert, W. B. ______________________ 107
Boschert, R. G. ______________________ 282

 

 

  
 
 

 

  
 
  

 

 

 

 

 

 
  
 

Page
Yemen Arab Republic —Continued
hydrogeologic mapping ___________ 241
remote-sensing studies ___- __- 241
topographic mapping __ _ 271
USGS ofiices ________ __ 325
Yugoslavia, geochronology ____________ 156
Z
Zeolite _______________________________ 2,13
‘ Page
Botbol, J. M. ________________________ 17,265
Botsford, M. L.
Bowen, R. W. _____
Bowman, Harry
Boyce, R. E. _________________________ 134
Brabb, E. E. _________________________ 58, 201
Brackley, R. A. ______________________ 82
Braids, O. C. ________________________ 224
Branson, F. A. ______________________ 186
Bredehoeft. J. D. __ 179
Bregman, M. L. __ ________________ 50
Brew, D. A. ___- ................ 71,77
Bricker, 0. P. _______________________ 158
Briggs, C. L. _________________________ 236
Britten, L. J. -__- 184
Broadhead, T. W. _ 6
Brobst, D. A. ___- 9
Brock, M. R. ______________________ 264,266
Brockman, S. R. _____________________ 216
Broenkow, W. W. _______________ 128
Brokaw, A. L. __________________ 216
Bromfield, C. S. _ 17
Brookins, D. G. ______________________ 35
Broom, M. E. ________________________ 97
Brosgé, W. P. _______________________ 66
Brougham, G. W. ____________________ 143
Broussard, W. L. _____________________ 85
Brown, D. P. 90
Brown, D. W. 185
Brown, F. W. 236
Brown, R. D., 201
Brown, R. F. 178
Bruns, T. R. _________________________ 129
Bryant, Bruce _______________________ 7,50
Buchanan-Banks, J. M. ______________ 203
Bucknam, R. C. ______________________ 54
Bufe, C. G. _________________________ 199,200
Bunt, R. J. ___ -_ 113
Burchett, C. R. __ - 96
Burchett, R. R. _ - 45
Burford, R. O. ________________________ 201
Burkholder, R. E. ____________________ 174
Burky, J. D. ________________________ 127, 133
Burmeister, I. L. _____________________ 193
Burns, A W
Busby, M W

 

Bushnell, Kent
Byerlee, J. D. ________________________ 200

C

Cady, J. W., Jr. _____________________ 146
Cain, J. C. ____________________
Calk, L. C. __________________________

 

 

 

 
  

368

Cameron, C

Cameron, R

Campbell, D

Campbell, W.

Campbell, W. J.

Campbell, W. L. ____________________ 16,171
Cannon, W. F. ________________________ 10
Cardwell, G. T. 226
Carline, R. F. __ 186
Carlson, G. H. _ 219
Carlson, J. E. ________________________ 53,76
Carlson, P. R. ________________________ 132
Carnevale, M. J. ______________________ 39
Carr, J. E. ___________________________ 105
Carr, M. H. __ 228
Carr, W. J. __________________________ 61
Carroll, R. D. ________________________ 214
Carron, M. K. ________________________ 236
Carten, R. B. ________________________ 54

Carter, W. D.
Case, J. E. ---
Castle, R. O. _-

  
  

 

 
 
  

  

 

   
 

Caswell, W. W. ______________________ 83
Cathcart, J. B. ____________________ 259,266
Cathrall, J. B. _______________________ 15
Causey, L. V. ________________________ 119
Chandler, M. E. J. _ 174
Chao, E. C. T. _____________________ 232,233
Chao, T. '1‘. ___________________________ 16
Chang, T. C. _________________________ 195
Chapman, R. M. ______________________ 65, 67
Chappell, B. W. __ _ 160
Chen, A. T. F. -_ _ 201
Chicko, R. S. _____ _ 194
Chidester, A. H. ______________________ 265
Childers, J. M. ________________ 109
Chisholm, J. L. 87
Christ, 0. L. ____-____________________‘ 14s
Christensen. C. N. 106
Christian, R. P. ____________________ 235,236
Claassen, H. C. ______________________ 213
Clague, D. A. ________________________ 152
Clardy, B. F. _______________________ 76,174
Clark, A. L. -_ ______________ 263, 264
Clark, B. C. ___ ............. 228
Clark, M. M. ___- __ 204
Clem, Richard ________________________ 62
Clifton, H. E. ______________________ 129
Cloud, P. E., Jr. 177
Coats, R. R. _______ 53

 

 
   
  

Cobban, W. A.

Coch, N. K. ___ __ 13
Coker, A. E. ___ __________ t 246
Coleman, R. G. _ _ 156, 263, 264, 268
Collier, C. R., Jr. ___________________ 93,168
Collins, D. ___________________________ 163
Colton, R. B. _____ _ 209

 
 

 

 
 

Connor. C. W. __ 42
Connor, J. J ___ _ 159,225
Conomos, T. J. _______________________ 128
Cook, H. E. _____________________ 55, 133, 134
Coombs, D. S. ________________________ 157
Coonrad, W. L. ______________________ 70
Cooper, A. K. ___. 130
Coplen, T. B., II ______________________ 111
Cordell, L. E. _______________________ 51
Cordes, E. H. _______________________ 92,246
Cory, R. L. ________________________ 124,134
Cosner, 0. J. __ 87
Cox, A. V. __-- 142
Cox, D. P. _________ -_ 17
Cragwall, J. S., Jr. __________________ 124
Craig, G. 5., Jr. _____________________ 183
Craig, L: C. _________________________ 77
Crandell, D. R. _______________________ 212

Creasy, S. C. _________________________ 5

 

INVESTIGATOR INDEX

  

 
 

  
 

   

 

Page
Cressler, C. W. ______________________ 92
Cressman, E. R. _______________ _ 42
Criley, E. E. _-_ - 199
Crippen, J. R. _______________________ 217
Crist, M. A. __________________________ 108
Crittenden, M. D., Jr. ________________ 55
Croft, M. G. _________________________ 158
Crosby, O. A. _ _ 218
Cross, Whitman ___ _________________ 3
Crosthwaite, E. G. __________________ 31
Crutcher, M. C. _____________________ 282
Csejtey, Béla _________________________ 69
Culler, R. C. ...... _ 188
Cunningham, 'D. R. _ _ 214
Cunningham, M. J. __ _ 214
Curtiss, D. A. _______________________ 168
Cushing, E. M. _______________________ 209
Cuttitta, Frank _______________________ 236

D

Daetz, Douglas ____~_ __________________ 253
Dalrymple, G. B. _______________ 132, 152, 153
Daly, R. A. ________ '_ ____________ 164
Damon, P. E. ______________ _ 31
Dane, C. H. ______ _ 47
Daniel, C. C., III _____________________ 93
Daniel, J. F. _________________________ 187
Daniels, D. L. _______________________ 42
Daniels, J. J. ________________________ 146
Danielson, T. W. - 209
_Davidson, D. F. ____________________ 259,264
Davidson, E. S. _______________________ 227
Davies, W. E. _______________________ 210
Davis, G. H.
Davis, P. A
Davis, R. E.
Davis, R. W.
Davis, W. M

 

Dearborn, L.
Deleveaux, M. H.

   

  

 

 
 

 
  
  
  

 

    

Denson, N. M. ___ _ 19,29, 159
Denton, E. H. ___ ____________ 25
Desborough, G. A. _________ 3, 13, 27, 156, 265
Detterman, R. L. _____________________ 70
Deutsch, Morris _____ _ 237,240,241
Devine, J. F. _______ 77,216
de Witt, Wallac‘e, Jr. _ 21
Dial, D. C. ___________________________ 101
Diaz, J. M. ___________________________ 230
Dibblee, T. W., Jr. ___________________ - 60
Dickey, D. D. _________________________ 61
Dickinson, K. A. _ 27
Dickson, F. W. _______________________ 4
Dietrich. J. H. ______________________ 201
Diment, W. H. ____________________ 140,141
Dinwiddie, G. A. ______ .5, _____________ 213
Dixon, H. R. _____ _ 35
D’Lugosz, J. J . _________________ 105
Dobrovolny, Ernest ___________________ 208
Dodge, F. C. W. ___________________ 155,270
Dodge, H. W., Jr. ____________________ 28
Doe, B. R. ________ __ 147,270
Donaldson, D. E. ___ __ 118,121
Donnelly, J. M. _- _ 31
Donovan, T. J. ______-_-_, _____________ 24,25
Doonan, C. J. ________________________ 83
Dorris, T. C. ...... 190
Dorrzapf, A. F., Jr. 197
Doty, G. C. _________ 213
Douglas, R. C. _______________________ 46
Dover, J. H. ____________________ 7,19,50,52
Downing, D. J. _______________________ 112
Drew, L. J. __________________ __ 17,18
Dudley, W. W. - 213
Duerr, A. D. ________________________ Z 221
Dufiield, W. A. _____________________ 31,151
Dunrud, C. R. _______________________ 207

 

 

 
 
 
 
 
  

 

  
 

 

  

  
   

Page

Durbin, T. J. ______________________ 110,179
Dutro, J. T., Jr. _____________________ 66,67
Dutton, C. E. ________________________ 44
Dwornik, E. J. _____________________ 235,236
Dyar, T. R. ________________________ 123,222
Dysart, J. E. __________________ 2 ______ 184

E
Eakin, H. M ________________________ 67
Eakin, T. E. _________________________ 109
Earhart, R. L. 270
Eaton, 2
Ebens, 224
Eccles, . . 111
Eggler, D. H. _______________________ 48
Ehlke, T. A. _________________________ 184
Ehrlich, G. D. ......... _ 184
Ellen, S. D. ____________ __ 53,208
Ellersieck, I. F. _ - 68
Elliot, D. H. _________________________ 273
Ellis, M. Y. __________________________ 282
Ellsworth, W. L. _______________ ___ 200
Elston, D. P. -Q ________________ _- 142,244
Emery, P. A. __ __ 111
Embree, G. F. ___ ________________ 46
Emmett, L. F. ._ ___________________ 186
Emmons, P. J. ______________________ 97
Endo, E. T. _________________________ 150
Engberg, R. A. ___- 158
England, A. W. __ 243
Engler, Kyle ______ 122
Epstein, A. G. _________________ : ______ 39,40
Epstein, J. B. ____________1 __________ 39, 40
Erdman, J. A. ___________ 224,225
Erdmann, D. E. ________ _ 198
Ericson, D. W. ___. _ 85
Espenshade, G. H. ___________________ 41
Espinosa, A. F. ______________________ 201
Evans, H. T., Jr. _ 149
Evans, J. G. _ 266
Evans, R. K. ___ 8
Evans, W. E. 247,248
Everett, D. E. ________________________ 101
Ewart, C. J. ________________________ 112,220

F
Fabbi, B. P. _________________________
Fabiano, E. B. _______________________
Fader, S. W. ________
Farrow, R. A. -. ______
Fassett, J. E. __
Faulkner, G. L.” ____________________ 124,222
Faust, C. R. _________________________ 166
Fayard, L. D. __________ ' _____________ 135
Federspiel, F. E. ____________________
Felsheim, P. E. _______
Fernandez, Mario, Jr.
Ferreira, R. F. ______________________
Ficke, J. F. __________________________ 122
Ficklin, W. H. _______________________ 195
Fidler, R. E. ___-

Finkelman, R. B.
Fisher, C. K.

Fishman, M. J.
Fiske, R. S. __
Fitch, H. R. ___-
Flanigan, V. J. ______________________ 146
Fleck, R. J. ________________________ 271,272
Fleck, W. B. ___

  
 

Flippo, H. N., Jr. _ 219
Fogarty, D. J. _ - _ 220
Foote, R. Q. _________________________ 20
Forbes, R. B. ________________________ 66, 70
Force, E. R. _________________________ 13

 
 
 
 

 

   

 
 

Page
Ford, A. B. _________________________ 71,272
Foster, H. L. _________________________ 67
Foster, J. B. _________________________ 116
Fouch, T. D. __________________ 22
Fournier, R. O. -__- - 141, 165, 166, 263
Fox, J. E. ___________________ 21,25
Fox, K. F., Jr. ______________________ 57,62
Frank, David ________________________ 212
Frank, F. J. _______________________ 114,168
Frederick, B. J. ______________________ 82
Freeman, V. L. __ 7
Freethey, G. W. ______________________ 118
Frickel, D. G. _______________________ 169
Friedman, Irving ____ 16, 25, 141, 156, 161, 162
Frimpter, M. H. _____________________ 115
Froelich, A. J. __ _ 210
Fuis, G. S. -_- 199
Films], T. E. _________________________ 204

G

Gabrysch, R. K. _____________________ 226
Gafl, F. E. ___________________________ 31
Gafiney, J. W. _______________________ 37
Gair, J. E. __________________________ 1
Gallaher, J. T. __ __ 87
Garber, M. S. __ _____________ 121
Gard, L. M., Jr. ___________ 164,216
Garrison, L. E. ______________________ 170
Gaskill, D. L. _________________________ 2

Gates, J. S. .___
Gawarecki, S. J.
German. E. R. -

 

 
 
 

 
 

 

     
 

  
  
 

 
  

  
 
   

   

Gerrild, P. M. _______________________

Gibbs, J. F. _______________________ 201,204
Giese, G. L. _____________ _ 187
Gilbert-Tomlinson, Joyce _ _ 176
Gillespie, J. B. __________ _ 178
Gilroy, E. J. _________________________ 122
Glancy, P. A. ______________________ 114,217
Glanzman, R. K. ________ _ 12
Glass, W. R. ____________ __ 220
Gleason, J. D. _ 161,162
Glenn, J. L. _________________________ 135
Glick, E. E. ________________________ 76
Gloersen, Per ......................... 195
Glover, Lynn, 111 ____________________ 177
Goddard, K. E. _- .. 98
Godfrey, R. G. _-. ....... 82
Goetz, A. F. H. _____________ 243
Goetz, C. L. ........................ 89,221
Gogel, A. J. _________________________ 101
Goldberg, M. C. ._-- 198,246
Goldsmith, Richard __ -_ 35,37
Golightly, D. W. _-- 197
Gonthier, J. B. _______________________ 114
Gonzalez, D. D. ____________________ 213,214
Goodwin, C. R. nu _ 135
Gott, G. B. _________ - 15
Granger, H. C. - - 28
Grant, R. S. _________________________ 224
Gnntz, Arthur _______________________ 131
Green, A. W., Jr. _-_ _ 144
Green, M. W. _______ .. 28
Greene, H. G. _- -128, 211
Greenland, L. P. ___________________ 196,236
Greenwood, W. R. __________________ 270, 271
Griscom, Andrew ______________ _- 56
Grolier, M. J. _________________ _- 241
Grommé, S. C. .. 141,142
Grout, F. F. _________________________ 44
Growitz, D. J. ______________________ 87
Grubb, H. F. ________________________ 90,179
Grybeck, D. A. _______________________ 71
Gualtieri, J. L. __ - 9
Gude, A. J., III __- _________________ 13
Guetzkow, L. C. _ _______________ 218,219

Guild, P. W. __________________ 1, 76, 263, 264

 

INVESTIGATOR INDEX

Page
Gulbrandsen, R. A. __________________ 259
Gunard, K T. ..... . 219

   
 

Guswa, J. H. ____ ____ 82,115

Gutentag, E. D. _ _____ 223

Guy, H. P. ________________________ 124,250
H

Haas, J. L, Jr _____________________ 33

Hadley, D G ________________________ 271

Hadley, J B _. ____ 77

 
 
 
 
 
 
 
  
   
  

Hadley, R. F. _

Haeni, F. P. -- _____ 81
Haffty, Joseph ________________________ 12
Hail, W. J., Jr.

Haire, W. J. _______

Halberg, H. N.
Haley, B. R. _____
Halgerson, Ron
Hall, C. A., Jr.

 
 
 
 
 

 

  
 
 
 
  

  
 
  

 

Hall, D. C.

Hall, R. B.

Hall, W. E.

Halley,

Hamachi, B. R. ______________________ 203
Hamecher, P. H. _____________________ 181
Hamilton, J. C. ______________________ 19
Hamilton, L. J. -_ 105,106
Hamilton, M. S. . _______________ 151
Hamilton, T. D. .- __________ 67
Hamilton, W. B. _____________________ 267
Hammarstrom, J. G. __________________ . 233
Hampton, E. R. _____ .__ 97, 209
Hanna, W. F. . ..... 60. 265
Hansen, B. P. _ _______ 82
Hansen, R. L. ________________________ 242
Hanson, R. L. ________________________ 188
Hardee, Jack _______________ 192
Hardison, C. H. ____________ 218
Hardy, E. E. __ _______ 255
Hare, P. E. __________________________ 57
Harenberg, W. A. ____________________ 113
Harmsen, Lynn ______________________ 217
Harrill, J. R.’ ________________________ 109
Harris, D. D. -._ _ 115
Harris, L. D. _________________________ 21, 39
Harrison, J. E. _______________________ 3
Harsh, P. W. _______________________ 201
Hart, D. L., Jr. ______________________ 105
Hasbrouck, W. P. _ -_ 146
Haushild,W. L. _ ______ __ 135
Hauth, L. D. ____________ __ 218
Hawkinson, R. O. ____________________ 122
Hawley, C. C. _______________________ 65
Hayes, L. R. _. _ 95
Hayes, P. T. ___ __ 42
Hays, W. H. ___ _- 50
Head, W. J. _________________________ 180
Healy, J. H. ________________________ 200
Hearn, B. C., Jr. ____________ 31
Hedge, C. E. ___________ _ 50, 156,160
Hedlund, D. C. -_ ______ 6
Hedman, E. R. _______________________ 182
Helgesen, J. O. ______________________ 85
Helley, E. J.

Helm, D. C. _______

Helz, R. L. __

Hem, J. D. __________________________
Hemingway: B. S. ____________________ 148
Hemley, J. J. ________________________ 148
Hemphill, W. R. ______________________ 242
Hendricks, E. L. - 124
Hendricks, J. D. _____________________ 31
Henry, T. W. _______________________ 174
Hepburn, J. C. ______________________ 36
Hard, D. G. _________________________ 58,59
Herz, Norman _______________________ 13

 

 

369

  
 
 

 
 

 

Page
Hess, A. E. ___________________________ 145
Hey], A. V. ______________________ 13,16, 269
Hietanen, Anna _______________________ 56
Higer, A. L. ___________________ __ 246
Hildreth, C. T. - __ 38
Hill, D. P. _______________________ 199
Himmelberg, G. R. __________________ 61
Hinds, J. S. _________________________ 47
Hines, M. S. _________________________ 97
Hite, R. J. _______ 216,271
Hjalmarson, H. W. _________ 110
Hoare, J. M. _________________ 70
Hobba, W. A., Jr. ___________________ 88
Hobbs,
Hobbs,
Hodge,
Hodges, R
Hofstra, W. E. _______________________ 97,98
Hoggan, R. D. _______________________ 46
Holley, E. R. ________________________ 182
Hollyday, E. F. _____________________ 96, 247
Holm, R. F. _____ _-__ 31

   
 
 
 
 
 
 

 
  

  
 

 

 

    
  
  
     
    

Holmes, C. W. _ ____________ 126,127
Hoose, N. ______________________ 206
Hoover, D. B. ________________________ 30
Hopper, M. G. _______________________ 201
Hopkins, D. M. ...... __ 67
Horn, G. H. _________ -___ 29
Horne, G. S. _________ __-_ 172
Hostetler, P. B. ______________________ 148
Hotchkiss, W. R. ___________________ 103, 209
Hotz, P. E. ______________ _ 55
Houston, R. S. ____________ __ 155
Howell, D. G. ___- .. 128
Hoxie, D. T. ________________________ 108
Hubbert, M. K. _______________________ 23
Huddle, J. W. _________________ _ 54
Hudson, J. H. __________________ ___ 25
Huebner, J. S. _______ 149,235
Huffman, Claude, Jr. _________________ 19
Hull, J. E. ________________________ 116,121
Hult, G. F. ___________________________ 85
Hummel, C. L. _______________________ 65
Hunn, J. D. ...... -_ 89
Hutchinson, C. B. _ ______ 89, 91
Hyde, J. H. __________________________ 212
I
Ingle, J. C., Jr. _____________________ 128
Irwin, W. P. 205
J
Jackson, D. B. _______________________ 30
Jackson, E. D. ______
Jackson, N. M., Jr. __________________ 218
Jaeger, J. C. __________________________ 151
James, O. B. _________________________ 233
Jamieson, I. M. ______________________ 140
Janzer, V. J. __-- 215
Jeanloz, Raymond 48
Jenkins, E. D. ___ 100
Jenkyns, H. C. __________________ 134
Jennings, M. E. _________________ _- 135
Jobson, H. E. _ 192
Johnson, A. I. - ________________ 117,124
Johnson, C. ________________ 218,219

G
Johnson, D. A
Johnson, F. A.
Johnson, G. H.
Johnson, G. R
Johnson, J G

 

Johnson, K. G. ____________________ 217,219
Johnston, M. J. S. ________________ 199,200
Jones, B. F. 157
Jones, B. L. -_ ____________________ 112
Jones, C. L. ________________________ 216

370

 
  

  

 

     
 
   

Page
Jones, D. L. _________________________ 69,70
Jones, J. E. __ 188
Jones, J. J. _____ _ 272 '
Jorgensen, D. G. __________ _ 115
Joyner, W. B. ____________ _ 201
Junger, Arne _______________________ 23, 127

K

Kahan, A. M. ________________________ 242
Kaltenbach, J. A. 176
Kam, William ______ 223
Kaneps, A. G. __________________ 134
Karamata, Steven ______________ 156
Karklins, O. L. ______________________ 173
Katzer, T. L. ________________________ 114
Kaufman, M. I. __ 184,222
anada, K. ___: ______________________ 151
Kaye, C. A. ______________ 37
Kazmann, R. G. 122
Keefer, T. N. ________________________ 220
Keefer, W. R. -_ __________ 19, 108
Keighin, C. W. _ ___________ 27
Keil, Klaus __ _ 228
Keith, J. R. __________________________ 225
Keith, T. E. C. ______________________ 67

Kelley, J. 5., Jr.
Kelly, T. L. __
Kelfs, K. R. _
Kennedy, V. C. _________________
Kernodle, D. R.

Kernodle, J. M. ___________________ 179, 190
Ketner, K. B. ________________________ 54
Keys, W. S. _____ 124, 145, 193, 215

   

Kiilsgaard, T. H. _ 8, 264, 265, 270

  
  

Killen, J. M. _______________ 193
Kimmel, G. E. _______________________ 224
Kimrey, J. O. ________________________ 90
King, K. W. - ____________ 199
King, P. B. _- ____________ 76
Kinney, D. M. _ __ 264
Kistler, R. W. _____________________ 153,161
Kiteley, L. W. _______________________ 47

Klausing, R. L. _
Klein, J. M.

    
 
 
   

Knapp, D. G. ________________________

Knebel, H. J. ________________________ 125
Knight, A. L., Jr. ___________ 88
Knottek, R. W. _________________ 180
Koch, N. C. ___ 106

Kosanke. R. M.
Koski, R. A. _____________________
Koszalka, E. J. _
Koyanagi, R. Y.
Kramer, T. M. _
Krause, R. E. _________________
Krimmel. R. M.

Kroll, C. G. __________________________

Krushensky, R. D. ____________________ 72
Kuberry, R. W. __ .. 144
Kuhn, P. M. __________________ _ 195

Kume, Jack

 
 

Kuntz, M. A. ________________________ 156
Kvenvolden, K. A. ___________________ 57
Kwan, T. V. ________________________ 179
L
Lachenbruch, A. H. __________________ 140
Laenen, Antonius ______________ 114, 168, 188
Lahr, J. C. ___________________________ 199
Lajoie, K. R. ___________ 57,201, 202,204,211
Lamar, Donald _______________________ 238
Lambert, P. W. __ __ 21,25
Lambert, T. W. ____________ __-_ 93
Land, L. F. _____________________ 90,91,179

 

INVESTIGATOR INDEX

 
 
  

Landis, E. R. __
Landis, G. P. -

    
 
  

 

 

 

Langer, J. ____________________

Langer, W. H. _______________________ 38
Lanphere, M. A. ____________ 68,132, 153,156
Lansford, Myra ______________________ 198
LaPoint, P. J. I. _ _ 48
Lappala, E. G. ________ 103
Lara, O. G. ____________ 218
Larsen, F. D. ________________________ 38
Larson, D. C. ________________________ 119
Larson, S. P. ___ _ 84, 119, 123, 179, 223
Lathram, E. H. _ ______ 237,239
Lavery, F. G. ___ __ 284
Lawson, D. E. _______________________ 130
Leap, D. I. __________________________ 213
Leavesley, G. H. ___________________ 99, 179
Lee, F. T. ___________________________ 207
Lee, K. Y. __ 40
Lee, Reuben _____________________ 220
Lehrman, N.

Leifeste, D. K.

Leo, G. W. __________________________

Leonard, B. F.
Leopold, E. B.
Levings, G. W.
Lewis, B. D. _________________________

Lidster, W. A. --

   

 

 
  
 

Ligon, D. T., Jr. _____________________ 236
Lillie, E. G. __________________________ 196
Limerinos, J. T. ______________________ 183
Linden, E. C. ________________________ 98
Lindholm, G. F. __ __ 85,246
Lindler, Robert ________________ ___ 239
Lindsay, J. R. __________________ _ 148, 235
Lindsey, D. A. _______________________ 4
Lindskov, K. L. ______________________ 85
Link, M. H. _____ 59
Lipman, P. W. ______________ 32, 45, 147, 153
Lobmeyer, D. H. ______________________ 223
Lockwood, J. P. _____________________ 150
Lofgren, B. E. ___________________ 33, 60, 227
‘Lohman, S. W. - _-_- 216
Londquist, C. J. ________ __ 82, 115
Loney, R. A. ____________ __ 61
Lounsbury, R. W. ____________________ 210
Love, A. H. __________________________ 24

Love, J. D. __

  

  

 
 
  
  

 

  
 

Lovering, T. G. _ ________ 15
Lowham, H. W. __ 182
Lowrie, R. L. _______________________ 209
anchitta, B. K. ___________________ 230, 237
Ludwig, K. R. __ ________ 162
Lusby, G. C. _ ________ 169
Luzier, J. E. _________________________ 86
M

Mabey, D. R. ________________________ 30
MacCary, L. M. _________ 108
Mach, Darrell ___________ 238
Machette, M. N. _____________________ 51
MacKenzie, F. T. ____________________ 158
MacKevett, E. M., Jr. - _ 68,69
Maclay, R. W. -___ _- 106
MacLeod, N. S. - _ 31
Main, R. J. __________________________ 143
Major, T. J. _________________________ 97
Malone, Stephen ___ 212
Malva-Gomes, A. I. 282
Mamay, S. H. _____ 174
Mankinen, E. A. 142
Mann, L. J. _________________________

Mann, W. B., IV
Marler, G. D. __
Marlow, M. S.

 

Martin, R. G., Jr. __________________ 126
Martini, E. ___________

Marvin, R. F. _--
Mast, R. F. _--

   
  

 

  

 

 

 

  
  
    
   
  
    

Masters, C. D. _________________ 264
Matson, N. A., Jr. __________________ 68,177
Mattick, R. E. _______________________ 20
Mattraw, H. C., Jr. _________________ 90,120
Maughan, E. K. - 22
Maxwell, C. H. 2
Maxwell, E. L. 238
May, R. J. __________________________ 162
Mayfield, C. F. ______________________ 66
Mayo, L. R. ..... ___ 124,171
McBride, M. S. -_ _____ 84
McCabe, J. A. __-- - 93
McCain, J. F. ______________________ 209
McCallum, M. E. _________________ 48, 49, 50
McCarthy, J. B., Jr. ................ 266
McCauley, J. F. ______________________ 229
McClymonds, N. E. 267
McCoy, G. A. ...................... 109,189
McCoy, H. J. _______________________ 92,121
McCrory, P. A. ____________________ 203,211
McCullough, M. M. ___________________ 134
McCullough, R. A. _ 100
McGrew L. W. __ 47
McGrew P. 0. ___ 47
McGuire, R. K. ___-.---_’ ______________ 264
McKee, E. D. ________________________ 53,77
McKee, E. H. ________________________ 31, 55
McKelvey, V. E. ______________________ 264
McKenzie, D. J. _-

McKenzie, W. F. ___________________ 165 166
McLaughlin, R. J.

McLean, K. S. _______________________ 284
McMahon, A. B. _____________________
McNulty, C. L. _____

McPherson, B. F. _
McPherson, E. M. _

 

 

  

McQueen, I. S. _______________________
Meade, R. H., Jr. ___________________
Meeks, D. C. _______

Mehnert, H. H. _ .. 6, 32, 45, 48, 50, 51
Meier, M. F. ___- _______ 124,171,247
Meisler, Harold ______________________ 86
Melvin, R. L. _________________________ 81
Mercer, J. W. __ _ 166
Merifield, Paul __ 238
Merritt. V. M _____ 6, 51
Meunier, T. K. ______________________ 282
Meyer, F. W. _________________ 121, 178, 186
Meyer, W. R. ___ _______ 107
Miesch, A. T. _________ _ 158,159
Middleburg, R. F., _ 220
Millard, H. T., Jr. ___________________ 19
Miller, C. D 212
Miller, C. H 214
Miller, F. K 60
Miller, M. H 2
Miller, M. S 9
Miller, R. F ______________________ 170,186
Miller, T. P _____________________ 63, 64, 65
Miller, W. L 186
Miller, W. R. 103
Mills, L. R. 221
Milton, D. J. 231
Minard, J. P. 40
Minkin, J. A. _____________________ 232,233
Missimer, T. M. _ _ 180
Molnia, B. F. ___ ________ _ 132
Mongan, C. E. _ ________ _ 215
Montoya, J. W. ______________________ 148
Moore, D. G. ______________________ 239,240
Moore, G. K. ______________________ 240,246
Moore, G. W. _______________________ 23,127
Moore, J. G. - _ 132,151

 

Moore, R. B. _________________________ 31

  
 
  
  
 

 

   
 
    
  
 
 
 
  

 

  
 

 

Page
Moore, W. ___________________________ 164
Moore, W. J. _____ 3
Moran, R. E. ______________ 221
Moreland, J. A. ___________ _ 113
Morgan, B. A. _________________ 13,155
Morgan, J. O. ._- ._ 259,271
Morris, H. T. __________________ _ 54
Morris, R. H. __________________ 216
Mortensen, C. E. ___ _ 199,200
Morton, D. M. _______________________ 60
Moses, T. H., Jr._; ___________________ 140
Mosier, E. L. ___-
Moxham, R. M. ______________________ 197
Moyle, W. R. ________________________ 112
Mrose, M. E. ___- __ 265
Muir, K. S. ______________________ 112
Mullineaux, D. R. _________________ 212
Muniz, Jose _____ -_ 127
Munroe, R. J. ___ ____________ 140
Murata, K. J. ___ ___________ 141,157
Murphy, J. J. ...... __ 223,224
Murphy, W. R., Jr. _____ 219
Murray, C. R. .......... 121
Musser, J. J. ______________ _- 93
Myers, V. I. ________________ _ 240
Myers, W. D. _. _ 50
Mytton, J. W. _______________________ 259
N
Nace, R L _________________________ 124
Naeser, C W 55,59,150
Nash, J T. 29
Nason, R. D. ....... _- 201
Nathenson, Manuel __________________ 33, 165
Nauman, J. W. ____________________ 190,191
Neeley, B. L., Jr. ___. 182
282
225
_ 36, 210
131
Nelson, W. H. _______________________ 163

Nemickas, Bronius _

  
   
  
   
 
  
  
 

Neuman, R. B. ___
Newell, W. L. ___
Newman, K. R. --. -__- 23

 

 

  
  

Newton, J. G. ___- 226,245
Nichols, D. R. -_ __ 201,209
Nichols, L. B. _________________ 199
Nichols, T. 0., Jr. _____ _ 207 208,209
Nichols, W. D. _____________ 110
Nilsen, T. H _______________ _ 58, 59, 201
Nixon, R. C ________________ - 284
Nkomo, I. T -- _ 27
Noble, R. L. _________________________ 24,25
Nolan, T. B., Jr. _____________________ 173
Norton, A. R. 19
Norton, J. J. _________________________ 18
Norton, S. A. ________________________ 35
Norvitch, R. F. ._ _ 119, 122,246
Novitzki, R. P. - __________________ 178
Nunes, P. D. ________________________ 236
Nuss, N. W. ___ 25
Nutter, L.VJ. _- 82
Nyman, D. J. ________________________ 102
O
Oakley, K P ________________________ 163
Oaks, R. Q. ......................... 13
Obradovich, J. D. ___________________ 51,163
O'Brien, N. R. ___- -_ 130
O'Connor, H. G. _ _________________ 101
O'Donnell, J. E. __ _________________ 30
O’Donnell, T. H. __ ___ 180
Oilfield, T. 'W. __ ___________ 146, 244
Ogilbee, William .. _______________ 268
O’Hara, C. J. ________________________ 36,37

 

INVESTIGATOR INDEX

   
 
      
   

Page

Olcott, P. G. _________________________ 85
Oldale, R. N. ___ __ 36,37
O’Leary, D. W. _ _________________ 38,244
Qliver, W. A., Jr. ____________________ 172
29

124

O’Neil, J. R. _____________ 160,161
Osterkamps, W. R. ______ _ 168
O’Sullivan, R. B. ________ 26
Otton, E. G. ___________ 119
Outcalt, S. I. _________________ __ 248
Ovenshine, A. T. _ 130
Overstreet, W. C. __ 15
Owens, J. P. _________________________ 40

 

 
 
 
 
 
  
 
 
 

  
  
  
 
 
  
 
 
  

Palaces. J. G. -- _____ 24
Palmer, C. M. 189
Pamic, Jakob 156
Pampeyan, E. H. ___ 203
Parks, W. S. ___ ______________ 210
Pascale, C. A. _ _____________ 89,222
Patton, P. C. _______ 169
Patton, W. W., Jr. _ _____ 65,67
Pavlides, Louis __________ 41
Pearl, J. E. ________________ 128
Pearson, D. L. ___________ 6
Pearson, F. J., Jr. 124
Pearson, R. C. _________________ 29
Pease, R. W. ________________________ 248
Peck, D. L. -_ 151,155
Peek, C. O. __________________________ 119
Pendleton, A. F., Jr. __________________ 118
Penman, H. L. _________ 187
Peper, J. D. __

Perkins, D. M. _____________________ 201,264
Perry, W. J., Jr.

Pessel, G. H. ______

Peterson, D; H.
Peterson, D. L.
Peterson, D. W.
Peterson, Etta
Peterson, Fred

 

Petri, L. R. _____

Pettijohn, R. A. _____________________ 81
Pezzetta, J. M. 193
Pfluke, J. H. - 200
Phair, George _ 154
Phipps, R. L. ________________________ 192
Pickering. R. J. - _____ 93,122
Pierce, K. L. __ _________ 30,209,216
Pierce, R. L. __ _______________ 175
Pierson, C. T. ___- __ 28
Pike, R. J. _______________ 231
Fillmore, C. L. _-_ ________ 42
Pinckney, D. J. ___- __ 184
Pinckney, D. M. ___- ___ 1
Pinder, G. F. ___- _- 179
Pitman, J. K. ___________ _- 18
Pitt, W. A., Jr. ________ __ 121
Plafker, George .- __ 65
Playton, S. J. ________________ _. 94, 170
Pluhowski, E. J. _____________ _ 124,250
Plummer, L. N. _ 157,158
Pohn, H. A. _________________________ 244

Pojeta, John,
Poland, J. F.

 

Pomeroy, J. S. ______________________ 36,210
Poole, F. G. _________________________ 4,22
Post, Austin 1'24,171
Potter, R. W., 111 ____________________ 33
Potter, W. D. ________________________ 218

 

  
 
 

 

 
 
 
 
 
  
 
 
  

 

  
  
  

 

 

 
   
 
  
  
 
 
  
  
  
  
 

 

 

Page
Powell, J. D. _________________________ 28
Powell, W. J. _________________ 88
Pratt, W. D. _______________ 9
Prescott, W. H. _________ __ 200
Prévot, Michel __________ _- 141
Price, Donald _____ -- 109
Price, L. C. _________________________ 24
Prichard, G. E. ______________________ 45
Prinz, W. G. _____ 43
Prostka, H. J. _______________________ 48
Prugh, B. J., Jr. __________________ 218,223
Prych, E. A. ________________________ 135
Q
Quifiones-Mérquez, Ferdinand _______ 189, 190
R
Rabchevsky, George __________________ 240
Radbruch-Hall, D. H. -_ 206
Radtke, A. S. ._ ....... 4
Ram, N. M. ____________ 183
Ramseier, R. 0. _______ _ 194,195
Randall, A. D. ________ ..._ 86
Randall, R. G. ..... 157
Randich, P. G. _______________ 105
Randolph, W. J. ____________ 170
Rankl, J. G. ______ 183,220
217
Rasmussen, L. A. ___________________ 171, 183
Ratclifi, M. A., Jr. - 24
Ratclifie, N. M. _____________________ 35
Rathbun, R. E. _ ________________ 183
Ratté, J. C _______ 2
Rau, W. W ______________ 128
Raub, W H ___- 124
Raynolds, R. G. ........... 239
Redding, J. M. ____________ - 134
Reed, E. C. _____ 45
Reed, Lawrence 246
Reed, L, A. 168
Reed, V. S. 230
Reeves, 121
Regan, R. D. _______________________ 146,147
Reimer, G. W. 30
Reimnitz, Erk - 180
Rein, R. D. ________________________ 25
Reinemund, J. A. -_ 263,264
Reiser, H. N. ______________ 66
Repenning, C. A. __ ________ 67
Reynolds, J. B. ______ __ 242
Reynolds, M. W. _____________ 21
Rhodehamel, E. C. _- ______ 20
Rice, D. D. _________________ _ 24
Richards, D. B. ____________ __ 119
Richards, P. W. --- ___ 163
Richmond, G. M. ___________________ 165,263
Richter, D. H. _______________________ 67,68
Ridenour, James 8
Ridgley, J. L. ________________________ 155
Riggs, H. C. _________________________ 181
Rima, D. R. 95
Rinehart, C. D. _______________________ 62
Riter, J. R., Jr. _____________________ 246
Roach, J. T.
Robb, J. M.
Roberts, A.
Roberts, A.
Roberts, R.
Roberts, R. ___-
Robertson, A. - 90,218
Robertson, E. C. _____ __- 51
Robertson, J. B. --_ 215
Robertson, J. F. _____________ 47
Robie, R. A. _____________________ 148
Robinove, C. J. _ _ 241, 259, 264
Robins, C. M. ________________________ 284

372

 

 

 

 

 

   

 

  
 

  
 
  

 
 
 
    

Page

Robinson, G. D. ______________________ 48,50
Robinson, Russell ___
Robison, J. H. ___.
Robison, T. M. ________________
Robson, S. G. _________________
Roddy, D. J. _______________________ 229,232
Rodis, H. G. _________________________ 90,91
Rodriquez, R. W. _
Roedder, Edwin _____
Rogers, A. M. _______
Rogers. C. L. ________________________
Rogers, R. H. ________________________ 246
Rogers, S. M. _-__ 87
Rorabaugh, M. I. _ 187
Rosasco, G. J. ___ 148
Rose, H. F., Jr. ________________ 228, 235, 236
Rose, P. R. _________________________ 106
Rose, W. J. _________________________ 186
Rosenblum, Sam ______________________ 15
Ross, D. C. _______ 205
Ross, R. J., Jr. _______________ 7, 45, 52, 173
Rossman. D. L. 266
Rowan, L. C. _________________________ 243
Rubin Meyer, ______________________ 165,212
Ruggles, F. H., Jr. _ __ 240
Runnegar, Bruce ______ __ 176
Runner, G. S. _________ ___ 220
Rush, F. E. ________________________ 114,223
Rust, R. H. _________________________ 194
Ryder, P. D. __ 185
Rye, R. 0. ___. 161

S
Sabey, Burns _________________________ 225
Saboe, C. W. _________________________ 219
Sainsbury, C. L. _____________________ 65
Sanchez, A. G. _______________________ 230
Sanchez, J. D. ______________________ 19
Sandberg, C. A. __ __ 22,173
Sanders, R. B. _______________________ 20
Sando, W. J. _______________________ 46,175
Sanford, T. B., Jr. __________________
Sarna-Wojcicki, A. M. ____________
Sass, J. H. __________
Sato, Motoaki
Saulnier, G. J., Jr. ____________
Savage, J. C. ________________________ 200
Sawkins, F. J. ______________________ 161
Sayre, W. W. --_ _-_ 182
Schaber, G. G. _________ -_ 237, 244
Schaefer, D. H. ________ _ 112
Schafer, J. P. ____________________ .__ 37
Schafi‘stall, W. P. ____________________ 169

Schiner, G. R. ___-
Schirmacher, E. G. __

Schlanger, S. 0. ____ __ 134
Schlee, J. S. _________________________ 125
Schleicher, D. L. _____________________ 48
Schlesinger, Benjamin _______ 253

  
    

Schmidt, P. W. __ _ __.__;_ 209
Schmidt, R. G. ___
Schmitt, H. H. ______________________ 231
Schmoll, H. R. ______________________ 208
Schneider, D. L. __ ______________
Schneider, J. J. --
Schneider, V. R. __

   
  

  

Schneider, W. J. ______________ _ __ 257
Schnepfe, M. M. _______________ 195,235,236
Scholl, D. W. ________________________ 130
Scholle, P. A. ________________________ 25
Schopf, J. M. _1_-__ - 272
Schornick, J. 0., Jr. ___ 183
Schroder, L. J., H ______ __ 91
Schroer, C. V. _______________________ 114
Schultz, K. J. _______________________ 44
Schwarzman, E. C. _ .234
Scott, A. G. ________ 219

 

 

INVESTIGATOR INDEX

Scott,
Scott,
Scott,
Scott,
Scott, . .
Scrivani, E. P. ______________________ 128
Scully, D. R. _
Seaburn, G. E.

 

  
    
  
 

Seland, D. A. _______________________ 8, 28
Segerstrom, Kenneth _________________ 2
Seijo, M. A. _________________________ 94
Seitz, H. R. ___ _ 113
Selby, L. A. _________ _ 225
Sena, Joe __________________ 108
Senftle, F. E. __________________ 26, 147,236
Serebreny, S. M. _____________________ 238
Shacklette, H. T. _ _________ 15
Shah, N. J. ________________ 246
Shampine, W. J. __ __ 185
Shapiro, Leonard _____________________ 196
Sharp, R. P. _____ * ____________________

Sharp, W. N. -_
Shaw, D. R. __

Sheppard, R. A.
Shergold, J. H.
Sher-ill, M. G. ________________________
Shervais, S. W. ___-
Sherwood, C. B., Jr. _ __ 92, 120,121,192, 221

 

    
 

Shinn, E. A. 25
Shown, L. M. ______________________ 169,182
Shride, A. F. ________________________ 39
Shulters, M. V. __ 188
Shultz, D. J. __ 183
Sigafoos, R. S. _ 192,212
Signor, D. C. _________________________ 178
Silberman, M. L. ____________________ 54,162

Silver, E. A. _____
Simmons, C. E.
Simmons, G. C.
Simmons, J. H.

 

  
  

Simoni, T. R., Jr. ___________________ 59
Simons, F. S. ________________________ '7, 52
Simpson, S. G. _ ________________ 244
Sims, J. D. ______ 205
Sims, P. K. ‘ ___________________ 44
Sinclair, W. C.

Singer, D. A. _________________________

Sirkin, L. A. ._
Sisler, F. D. __

 

Skelton, John ______________

Skinner, J. V. _______________ ___
Skipp, ’Betty _________________________ 46, 50
Skrivan, J. A. _________________ 111, 112, 179
Slack, K. V.

Slack, L. J.

Slagle, S. E.

Sliter, W. V.

Sloan, C E.

Small, T A.

Smith, B. D.

Smith, G. 1.

Smith, J G.

Smith, J P.

Smith, J. T.

Smith, R. L.

Smith, Winchell

Smoot, G. F. ______________________ 124, 192
Snavely, P. B., Jr. ____________________ 128
Snider, J. L.

Snyder, R. P.

 

 

Sohl, N. F. ___________________________
Soister, P. E.

Sorauf, J. E. 172
Sorensen, J. E. ______________________ 282
Sorensen, M. L. ______________________ 55

 

 

 

Stanley, W. D. _________________ 145, 146, 167
Stearns, C. O. _______________________ 144
Steele, T. D. ___________________ 122, 222, 223
Steen-McIntyre, V. C. 216
Stephens, D. W. ______________________ 183
Steppe, J. A. _________________________ 200
Stern, T. W. _________________________ 41

 
 
   
 
 

Stewart, G. L. _______________________
Stewart, J. H. __
Stewart, J. W. __
Stewart, S. W. __

 

  
  

Stone, C. G.

Stone, D. B.

Stone, H. L.

Stone, R. B.

Stoner, J. C.

Strong, Alan _________________________ 237
Stuart, W. D. L _______________________ 143
Stuart-Alexander, D.‘ E. _ ___________ 234
Stuckless, J. S. - ____ 27
Stulken, L. E. ______ 100,101
Sturrock, A. M., Jr. _________________ 192
Subitzky, Seymour ____________________ 181
Sulam, D. J. _________________________ 121
Sullivan, M. W. ______________________ 27
Sumsion, C. T. __ ' 107
Sun, R. J. ________________ 215
Susag, R. H. _________________ 123
Sutclifl‘e, Horace, 91
Sutter, J. F. _________________________ 273
Sutton, A. L., Jr. _ _ 197
Sutton, R. L. ________ - 234
Swallow, L. A. _____________ 220
Swanson, D. A. _________________ 62, 150, 152

Swanson, V. E.
Sweeney, J. H. _
Szabo, B. J. _-‘.
Szekielda, K. H.

 

Tabor, R. W. ________________________
Tai, Han ____________________________
Tailleur, I. L. _______________________
Tangborn, W. V.
Tarr, A. C. __‘___
Tasker, G. D, ______________ 84, 185, 218, 219
Tatsumoto, Mitsunobu ______________ 160,236
Taylor, F. A. ________________________
Taylor, G. C., Jr.
Taylor, J. C. _____
Taylor, M. E. _________

Taylor, 0. J. _________

Taylor, T. A. ______________________ 194,215
Terry, G. R. _________________________
Thaman, R. R. ___
Thatcher, L. L. _.
Thatcher, W. R. _
Thayer, T. P. ________________________
Theodore, T. G. ______________________ 5
Thomas, C. P.
Thompson, C. L.
Thompson, D. G.
Thompson, T. H.
Thompson, W. B.

 

 

 

Thorarinsson, Sigurd“: _______________ 241
Thordarson, William __________________ 214
Thorpe, A. N. 236
Thurber, H. K. 9
Tibbals, C. H. ________________________ 90
Tibbitts, G. 0., Jr. ___________________ 268
Tidball, R. R. ______________________ 224,225
Tilley, L. J. _________________________ 191

 
 

Page
Tilling, R. I. _______________________ 150,157
Tinsley, J. C., III ___- _ 202,211
Tobin, R. L. ______________ 16’!
Todd, V. R. ___ ___- 54, 61
Tomkins, D. H. _______________________ 127
Tooker, E. W. _______________________ 264

Toulmin, Priestley, III __

 
 
  
  

 
  

 
 
 

Tourtelot, E. B. _____________ 12
Tourtelot, H. A. _- _ 225
Towle, J. N. __________________________ 146
Tracey. J. 1., Jr. 164
Trainer, F. W. 104
Trapp, Henry, 91
Trent, V. A. 42
Trescott, P. C. 179
Trimble, D. E. 209
Troitskaya, V. . 144
Tmesdell, A. H. ________________ 141, 165. 166
Truman J. F., Jr. _____ 168,169
Trumbull, J. V. A. ___ __________ 127
Tschanz, \C. M. ...... __ 7, 8, 12, 52, 265
Tschudy, 1R. H. ____________________ 51,175
Tsivoglou, E. C. ______________________ 224
Tuchek, E. T. _________ . 8
Turner, D. L. _______________ 70
Turner, J. F., Jr. 89,187
Turner, R. M. ________________________ 192
Twenter, F. R. ______________________ 84
Tweto, O. L. ________________________ 76

Ulrich, G. E.
Unger, J. D.

 

  
 
   
 

    

Urban, T C
V
Vacher, H. L. ______________________ 158
Van Alstine, R. E. ._ 10
Van Denburgh, A. S. 223
Van Driel, J. N. ____________________ 210
Van Horn, Richard _________________ 206
Van Noy, R. M. ........ __ 8
Vedder, J. G. __-_ ________ 23,127
Viets, J. G. ______________ 16
Voight, W. M. ______________________ 282
Volckmann, R. P. ____________________ 72
von Huene, R. E. ____________________ 129
W

Wagner, H. C. _________________ 23,127,203
Wagner, L. A. ______________________ 181
Wahl, K. D. ________________________ 178
Wah], K. L. ___________ 181,182
Wahrhaftig, Clyde _______ ___- 68
Walker, E. H. --_ ___ 82, 83
Walker, F. K. _ __________________ 20
Walker, G. W. ______________________ 32, 76
Walker, R L , Jr. __________________ 86

 

INVESTIGATOR INDEX

  
 

 
 

Page
Walker, Sylvia ______________________ 246
Wallace, R. E. ________________________ 206
Waller, B. G. ___ - 90,221
Waller, R. M. ___ _____ 180
Wandle, S. W., Jr _____ 83
Wang, Frank ________________________ 259
Ward, D. E. ________________________ 42
Ward, F. N. _____________ _ 16,195
Ward, P. L. ____________ 199
Warner, J. W. -- _ 112
Warren, C. G. _______________________ 28
Warren, D. K. ______________________ 192
Warren, W. M

Warrick, R. E. ______________
Watkins, J. A.

 

Watson, Kenneth ____________________ 33
Watson, R. D. ________________________ 242
Watts, K. 0., Jr. ____________________ 17
Wayenberg, J. A. ____________________ 195
Weakly, E. C. 101

Webber, E. E.
Weber, F. R.
Weber, G. E.
Weber, W. G.
Webster, D. A. ______
Webster, W. J., Jr. __
Wedow, Helmuth, Jr.

   
    

 
 

 
 

 

 
  
  

Weeks, E. P. ________________________
Weeks, J. B. ________________________
Weeks, W. F. ________

Wehde, M. E. ______

Wehmiller, John _- 7
Weiblen, P. W. ______________________ 235
Weinstein, H. G. ____________________ 179
Weir, J. E., Jr. ________________ __ 214
Weis, L. A. ___________________ -_ 217
Weis, P. L. _- ' ______ 13
Welder, F. A. __________________ 99,100,179
Wells, F. C. _________________________ 102
Welsch, E. P. ________________________ 16
Wentworth, C. M. __________ 57, 201,203, 208
Wershaw, R. L. _ ___________ 184
Wesson, R. L. __ ______________ 200,201
West, W. S. _____________________ 6
Westfall, A. D. ______________________ 181
Wetlaufer, P. H. _____________________ 243
White, A. F.

White, D. E.

White, W. F.

Whitebread, D. H. ___________________ 54
Whitehead, R. L. ____________________
Whitfield, M. 8., Jr.

Whitlow, J. W. ______

Whitmore, F. 0., Jr.
Wibben, H. C. ______________________
Wielchowsky, C. C.
Wilcox, R. E. _____________
Wilde, D. J. ____________
Wilheit, T. T. ________________
Wilhelms, D. E.
Wilhm, J. L. ________________________
Wilke, K. R. ________________________

 

 

373
Page
Wilkins, D. W. ______________________ 110
Willey, R. E. ________________________
Williams, D. R. ______________________
Williams, E. J. ______________________
Williams, J R. ______________________
Williams, N F. ___
Williams, P. L. ___
Williams, R. P. ___
Williams, R 8., Jr.
Wilshire, H G. ____________________ 155,234

Wilson, J. K.

198
Wilson, K. L. 195
Wilson, W. E.. 90

 

Windolph, J. F. ______________________ 6,43

 

  

 

 

 
  

   

  
   
   

Winner, M. D., 94

Winograd, I. J. 124

Winter, T. C. 189

Winterer, E. L. 134

Wires, H. 0. _ 192

Witmer, R. E. 255

Wolcott, D. E. 163

Wolf, R. J. __________________________ 85

Wolfe, E. W.

Wones, D. R.

Wood, G. H., Jr.

Wood, G. K.

Wood, J. D.

Wood, W. W. ________________________

Woodward, M. B. ___________________ 76

Worcester, R. D.

Worl, R. G. _____

Wright, James

Wright, R. H. _______________________

Wright, T. L. ______________________ 62,152

Wrucke, C. T. _______________________ 4
Y

Yanosky, T. M.

Yeend, W. E. __-_

Yerkes, R. F.

Yotsukura, Nobuhiro __________________ 182

Youd, T. L. ___________________ 201,206,209

Young, E. J. ________________________ 162

Young, H. L. ___. _ 179

Young, H. W. __________________ 113
Z

Zablocki, C. J. ____________ ‘ 147,150,157

Zachry, D. L. ___ ‘ _______ 76

Zack, A. L. __________________________ 95

Zand, S. M. __________________________ 184

Zartman, R. E. ______________________ 147

Zellweger, G. H. ____________________ 184

Zen, E-an ________ ___ 48,157

Zenone, Chester __ _______________ 118,208

Zielinski, R. A. _- ___________ 154,196,197

Zietz, Isidore ________________________

Zilka, N. ____________________________

Ziony, J. I. ____
Zohdy, A. A. R.

 

 

 

 

, “30 77" 7DAYS

Molluscan paleontology of the
lower Miocene Clallam Formation,
northwestern Washington

 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 976

 

 

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(m? I 1976'

Molluscan paleontology of the
lower Miocene Clallam Formation,
northwestern Washington

By WARREN O. ADDICOTT

 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 976

 

 

 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1976

UNITED STATES DEPARTMENT OF THE INTERIOR

THOMAS S. KLEPPE, Serrelary

GEOLOGICAL SURVEY

V. E. McKelvey, Diredor

Library of Congress Cataloging in Publication Data

Addicott, Warren 0.
Molluscan paleontology of the lower Miocene Clallam Formation, northwestern Washington.

(Geological Survey Professional Paper 976)

Bibliography: p. 36—39.

Includes index.

Supt. of Docs. no.: I 19.16976

1. Mollusks, Fossil. 2. Paleontology—Miocene. 3. Paleontology—Washington (State) I. Title. II. Series: United States
Geological Survey Professional Paper 976.

QE801.A2 564’.09797’9 76—608062

 

For sale by the Superintendent of Documents, US. Government Priming Oflice
Washington, DC. 20402

Stock Number 024—001—0287 1-9

CONTENTS

 

Page Page
Abstract __________________________________________________ 1 Molluscan paleontology—Continued
Introduction ______________________________________________ 1 Pelecypods ____________________________________________ 27
Acknowledgments ______________________________________ 3 Nuculidae ________________________________________ 27
Previous faunal studies ____________________________________ 3 Nuculanidae ______________________________________ 27
Molluscan fauna __________________________________________ 4 Solemyidae ________________________________________ 28
Biostratigraphy ____________________________________________ 6 Arcidae __________________________________________ 28
Introduction __________________________________________ 6 Glycymerididae ____________________________________ 28
Clallam Formation ____________________________________ 6 Mytilidae __________________________________________ 28
Provincial chronostratigraphy ______________________________ 12 Pectinidae ________________________________________ 29
Age and correlation ____________________________________ 12 Lucinidae ________________________________________ 30
Pillarian Stage ________________________________________ 18 Thyasiridae ______________________________________ 30
Paleoecology ______________________________________________ 18 Ungulinidae _--____-; ______________________________ 30
Bathymetry __________________________________________ 18 Carditidae ________________________________________ 30
Paleoclimate __________________________________________ 19 Cardiidae ________________________________________ 30
Molluscan paleontology ____________________________________ 20 Mactridae ________________________________________ 31
Gastropods ____________________________________________ 21 Solenidae __________________________________________ 31
Turritellidae ______________________________________ 21 Tellinidae ________________________________________ 31
Epitoniidae ________________________________________ 21 Veneridae ________________________________________ 33
Calyptraeidae ____________________________________ 21 Hiatellidae ________________________________________ 34
Naticidae __________________________________________ 22 Thraciidae ________________________________________ 34
Cassididae ________________________________________ 22 Cephalopods __________________________________________ 34
Ficidae ____________________________________________ 23 Hercoglossidae ____________________________________ 34
Muricidae ________________________________________ 23 Scaphopods ____________________________________________ 35
Neptuneidae ______________________________________ 23 Dentaliidae ________________________________________ 35
Fusinidae ________________________________________ 24 Fossil localities ____________________________________________ 35
Volutidae ________________________________________ 25 References cited __________________________________________ 36
Cancellariidae ____________________________________ 25 Index ____________________________________________________ 41
Turridae __________________________________________ 26
ILLUSTRATIONS
[Plates follow index]
PLATE 1. Crepidula, Semicassis, Neverita, Epitonium, Trochita, Turritella, Natica, Sinum, Polinices, Ficus, Trophosycon.
2. Bruclarkia, M olopophorus, Priscofusus, Trophonopsis, Crepidula, Cancellari‘a, Rectiplanes, Trophosycon.
3. Acila, N uculana, Amharax, Yoldia, Megasurcula, Ophiodermella, Xenuroturris, Ancistrolepis, M usashia.
4. Vertipecten, Solamen, Dentalium.
5. M ytilus, Glycymeris, Lucinoma, Modiolus, Anadara, Dentalium, Cyclocardia, Clinocardium, F elaniella.
6. Sp'wula, Macoma, Conchocele, Clinocardium, Cyclocardia, Solen.
7. Spisula, Macoma, Tellina.
8. Macoma, Katherinella, Dosinia.
9. Securella, Thracia, Panopea.
Page
FIGURE 1. Index map showing area of the report ____________________________________________________________________________ 1
2. Generalized geologic map showing distribution of the Clallam Formation and fossil localities ________________________ 2
3—7. Photographs showing:
3. Intertidal zone exposure of Dentalium-bearing concretionary sandstone ______________________________________ 7
4. Massive fossiliferous sandy siltstone at top of the upper member of the Twin River Formation __________________ 8
5. Intertidal zone exposure of the Clallam Formation showing intensively bioturbated sandstone __________________ 9
6. Conglomerate and conglomeratic sandstone lens in the Clallam Formation ____________________________________ 10
7. Intertidal zone exposure of basal concretionary sandstone of the Clallam Formation __________________________ 11
8. Chart showing stratigraphic position of fossil localities in measured sections ________________________________________ 12
9. Photograph showing chaotic blocks of sandstone in intertidal zone exposure of the Clallam Formation __________________ 13
10. Diagram showing correlation of the Clallam Formation with other sequences in the Pacific Northwest States and the
provincial marine chronologies ________________________________________________________________________________ 17

III

IV

TABLE

1.

\‘IO’CHJKCOM

CONTENTS
TABLES

Page
Mollusks from the Clallam Formation near Slip Point listed by Reagan (1909) with taxonomic revisions by D31] (1922)

and names recognized in this report __________________________________________________________________________ 4
. Mollusks from the Clallam Formation, northern Olympic Peninsula, Wash __________________________________________ 5
. Stratigraphic ranges of species from the Clallam Formation in the Pacific Coast Tertiary ____________________________ 14
. Specifically identified mollusks from the Clallam Formation that are not known to occur in other formations _________ 15
. Mollusks characteristic of the Clallam Formation __________________________________________________________________ 15
. Mollusks from the Clallam Formation suggestive of a provincial early Miocene age __________________________________ 16

. New species of mollusks described here and other species believed to be new but represented by material that is inade-

quate for formal description __________________________________________________________________________________ 20

MOLLUSCAN PALEONTOLOGY OF THE EARLY MIOCENE
CLALLAM FORMATION, NORTHWESTERN WASHINGTON

By WARREN O. ADDICOTT

ABSTRACT

The Clallam Formation is a predominantly marine sandstone with
minor conglomerate and siltstone exposed along the Strait of Juan de
Fuca in northwestern Washington. Marine mollusks occur through-
out the 600— to 800-m-thick formation but are especially abundant in
the lowest 240 m. New molluscan data from the Clallam provide the
paleontologic base for the Pillarian Stage, a provincial time-
stratigraphic unit of late early Miocene age. Until this study, the
Clallam had been assigned to the middle Miocene. The new lower
Miocene stage, characterized by the restricted stratigraphic range of
Vertipecten fucanus (Dall) and the restricted and overlapping ranges
of several other mollusks, can also be recognized in coastal Oregon
and southwestern Washington. Formations coeval with the Clallam,
and referable to the Pillarian Stage, include the Nye Mudstone, the
lower part of the Astoria Formation in the Grays Harbor and
Astoria-Grays River embayments, and at least part of the Hoh rock
assemblage. On the basis of molluscan data, the Clallam Formation
is also correlative with the upper part of the "Vaqueros" Stage of
California and, presumably, the uppermost part of the Poul Creek
Formation in the Gulf of Alaska. These correlations are compatible
with evidence from benthonic foraminiferal assemblages.

The molluscan fauna of the Clallam consists of 76 taxa, about
evenly divided between gastropods and pelecypods. Several species
are undescribed but only five new species—Semicassis pyshtensis,
Priscofusus goweri, P. slipensis, Ophiodermella olympicensis, and
Solamen snavelyi—are represented by material adequate for formal
description. All the Clallam molluscan assemblages represent inner
sublittoral depths (less than about 100 In). Qualitative analysis of
these assemblages indicates a gradual shallowing during deposition
of the formation. The highest strata in the Clallam contain coal beds
and are presumably nonmarine. This trend is the concluding phase
of an Eocene to Miocene depositional cycle in which maximum
depths, as determined from foraminiferal and lithologic evidence,
were attained during the Oligocene.

INTRODUCTION

The Clallam Formation is a moderately thick, pre-
dominantly marine sequence of sandstone, siltstone,
and conglomerate with a limited onshore distribution
along the northwestern margin of the Olympic Penin-
sula, western Washington (fig. 1). The Clallam repre-
sents the shallow-water regressive phase of a late
Eocene to Miocene depositional cycle, the greater part
of which is represented by the underlying Twin River
Formation. The Clallam is exposed between Clallam
Bay and mouth of the Pysht River (fig. 2). Resistant
sandstone and conglomerate strata within the Clallam

 

form a bold 12-km-long segment of coast bordered on
the west and the east by generally finer grained strata
of the Twin River Formation.

Marine mollusks are abundant in the lowest few
hundred metres of the formation, generally occurring
as scattered individuals entombed in place. Molluscan
assemblages also occur near the top of the formation.
The Clallam may be as thick as 800 m (Gower, 1960).

This report is a biostratigraphic and systematic
analysis of molluscan assemblages Within the Clallam
Formation. Biostratigraphic characterization of the
Clallam Formation and evaluation of the biogeo-
graphic significance of the fauna are both dependent
upon systematic analysis of the fauna.

 

   
 
 
     
 

  

   

 

 

 

 

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FIGURE 1.—Index map of northwestern Washington showing area of
report (fig. 2).

2 MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

124° 1 5'

 

I

[40:89, UW 270, UW 490
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Slip Point
M4677 ,

 
 
 
 

 

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48° 1 5' — Clallam
Bay
EXPLANATION
I)
5
E Clallam Formation
2
: ll!
_I|---
45
9 E Upper member
g “- Ttrc, conglomerate and sandstone
En E
5 :4
.E
5 .
(— Middle member

Contact, approximately located
Dorted where concealed

Fault, approximately located
U, uprhmwn side; D, downthrowrr ride

._+_.
Anticline, approximately located
_+_.
Syncline, approximately located
_fl.—o
Overturned syncline, approximately located

.——4
Measured section

at M4414
Fossil locality

 
  
 
 
  
 
 
 
  

0,0

1
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5 /

/Pi||ar Point

M4676, M5881

Pl LLAR POINT STATE
RECREATIONAL

"II" "III’; AREA

 

 

3M|LES

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| l | l I

5 Kl LOMETR ES

o—ro

FIGURE 2. —Distribution of the Clallam Formation and fossil localities. Based on mapping by Gower (1960) with minor modifications made
by Gower and Parke Snavely (written commun., January 1975).

The biostratigraphy of the Clallam is of especial
interest because the formation serves as the type sec-
tion for the Pillarian Stage (Addicott, 1976). It is also
important in recognition and correlation of the bound-
ary between the provincial lower and middle Miocene.
The provincial early-middle Miocene boundary has
been previously placed at the contact between the Clal-
lam and the underlying Twin River Formation by
Moore (1963), Addicott (1970a) and other molluscan
specialists. Although there is a well-defined change in
the megafauna across this boundary, evidence consid—
ered in this report suggests reassignment of the Clal-
lam to the provincial early Miocene. Foraminiferal
specialists, however, have generally placed the provin-

 

cial Oligocene-Miocene boundary at the base of the
Clallam Formation. This coastal section is well suited
as a standard section because fairly diverse, shallow-
water molluscan assemblages occur in both the Twin
River and Clallam Formations. Benthonic foraminifers
also occur across this boundary, permitting correlation
with the provincial microfaunal chronology.

The geographic location of the Clallam Formation is
especially critical in that it provides a potential
biogeographic tie between Miocene assemblages of the
Gulf of Alaska and Alaska Peninsula, far to the north-
west, with those of the conterminous United States (lat
33°—48° N.). The Clallam assemblages define the
northernmost occurrence of a late early Miocene mol-

PREVIOUS FAUNAL STUDIES 3

luscan province of relatively warm-water aspect in
coastal Washington and Oregon. This province is
characterized by a small, but persistent, element of
mollusks that are closely related to species living in
subtropical faunas at much lower latitudes along the
Pacific coast.

A modern taxonomic evaluation of the currently
known molluscan fauna is a necessary prelude to the
biostratigraphic and biogeographic analyses. Although
interest in the Clallam mollusks has spanned more
than 70 years since they were first noted in connection
with the discovery of coal seams near the top of the
formation (Arnold, 1905), there has never been a
thorough taxonomic or biostratigraphic treatment of
the entire fauna. A generalized systematic study of the
fauna was made by Reagan (1909) who recognized 25
mollusks in the Clallam, less than one-third the
number now known from the formation.

Paleontologic sampling of the Clallam Formation for
mollusks and other larger invertebrates during the
period 1968—74 has yielded a fairly diverse fauna of 76
species of mollusks, about evenly divided between gas-
tropods and pelecypods. Of the 11 taxa that are unde-
scribed, only five are represented by specimens suffi-
ciently well-preserved for formal description.

ACKNOWLEDGMENTS

I was aided in my fieldwork by Parke Snavely, Jr.,
Rowland Tabor, Norman MacLeod, Saburo Kanno,
John Miller, and James Pearl. Howard Gower and
Parke Snavely provided field maps and aerial photo—
graphs in addition to helpful discussions on the
stratigraphy and geologic structure of the Twin River
and Clallam Formations. Weldon Rau furnished data
on foraminiferal assemblages from the Twin River and
Clallam Formations. A. Myra Keen of Stanford Uni-
versity kindly lent material from the early collections
made by Harold Hannibal (Arnold and Hannibal,
1913) for photography and laboratory study. V. Stan-
dish Mallory made available collections from the
Burke Museum, University of Washington, for study.
Saburo Kanno, Tokyo University of Education, Japan,
furnished a specimen of Mytilus from Hokkaido for il-
lustration here. The critical comments of Howard
Gower, Ellen Moore, and Parke Snavely were benefi-
cial. Fossil photography is by Kenji Sakamoto.

PREVIOUS FAUNAL STUDIES

Molluscan fossils of the Clallam Formation attracted
the interest of several geologists during the early
1900’s after the discovery of coal seams near the top of
the formation (Gilman, 1896; Arnold, 1905). Notewor-
thy are the reports of Ralph Arnold (1905, 1906, 1909,

 

and 1913 [with Harold Hannibal] ), Albert B. Reagan
(1909), and Charles E. Weaver (1912, 1916a, 1916b).
These geologists briefly described the stratigraphic se-
quence of the Clallam Formation and also identified
molluscan assemblages from the coastal area between
Clallam Bay and Pillar Point. A few new mollusks
were described from these exposures by Reagan (1909)
and Weaver (1012). However, paleontologic investiga-
tion of the larger marine invertebrates of the Clallam
has not passed beyond the reconnaissance phase. Vir-
tually no additional work was done on the mollusks or
their biostratigraphy during the ensuing 60 years. A
few publications during this period, however, do con-
tain incidental references to Clallam taxa (Tegland,
1929; Etherington, 1931; Slodkewtisch, 1938; Durham,
1944; Stirton, 1960; Moore, 1963; Addicott, 1969,
1970a). While interest in the Clallam mollusks lan-
guished, detailed taxonomic studies of the closely re-
lated Miocene fauna of the Astoria Formation of Ore-
gon and southwestern Washington (Etherington, 1931;
Moore, 1963) and the early and middle Miocene faunas
of the Gulf of Alaska (Kanno, 1971) were completed.
Although these are useful in working with the Clallam
mollusks, the fauna of the Clallam contains many taxa
not previously known from Miocene formations in the
Pacific Northwest States and Alaska and is sufficiently
unique to warrant systematic description and analysis.

Arnold (1906) included marine shale, sandstone, and
conglomerate lying stratigraphically above the Eocene
Crescent Formation in his original description of the
Clallam Formation. Now almost all of this sequence is
included in the Twin River Formation of Brown and
Gower (1958). The name Clallam is retained for the
uppermost part of this middle Tertiary sequence be-
cause Arnold designated exposures at the very top of
his formation, between Clallam Bay and Pillar Point
(fig. 2), as the type locality. He recognized five faunas
[faunal assemblages] in his unrestricted Clallam For-
mation; only two are from the Clallam, as redefined
here; the other three are from the underlying Twin
River Formation. The two uppermost localities were
near Slip Point (fig. 2); 18 mollusks were listed from
them.

Reagan (1909) first described and illustrated mollus-
can fossils from the Clallam. Within the Clallam For-
mation as defined here, he recognized three successive
faunal “horizons”——actually assemblages—from three
localities at East Clallam [near Slip Point]. One of
these was described as intermediate between Arnold’s
(1906) two localities that are from the redefined Clal-
lam Formation. Twenty-seven of Reagan’s (1909, p.
170—173) species were from these three Miocene
localities in the Clallam. Six of these species, and a
variant of Tellina arctata (Conrad) [=Macoma arctata

4 MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

TABLE 1.—Mollusksfrom the Clallam Formation near SlipPoint listed by Reagan (1909, p. 1 72-1 73, and 181) with taxonomic revisions by Ball

(1922 ) and names recognized in this report
[A larger list of mollusks from the Clallam Formation (Reagan, 1909, p. 197—198—east Clallam»Neah Bay series) includes many species from strata now mapped as Twin River Formation]

Reagan (1909)

Gastropods:
Trochita inornata Gabb ________________________
Polynices (Lunatia?) olympidii Reagan, n. sp ,___
Polynices (Neverita) saxea Conrad ______________
Sigaretus scopulosus Conrad __________________
Pisania clallamensis Reagan, n. sp ____________

Pelecypods:
N ucula (Acila) castrensis Hinds ________________
Yoldia impressa Conrad ______________________

Petunculus patulus?
Pecten (Chlamys) fucanus Dall? ________________
Pecten (Chlamys) wattsi, var. morani Arnold? __
Pecten (Patinopecten) propatulus Conrad? ______
Phacoides acutilineatus Conrad ________________

Mactra gibbsana Meek ________________________
Tellina arctata Conrad ________________________
Tellina arctata, var.juana Reagan, 11. var ______
Tellina clallamensis Reagan, n. sp ____________
Metis alta Conrad ____________________________
Saxidomus gibbosus Gabb ____________________

Venus (Chione) clallamensis Reagan, n. sp ______
Venus (Chione) olympidea Reagan, n. sp. ______
Venus (Chione) angustifrons Conrad ____________

Trochita inornata Gabb ______________________
Amauropsis? oregonensis Dall D
___________________________________________ o

Sinum scopulosum Conrad __________________
?B uccinum clallamensts Reagan ______________

Nucula (Acila) conradi Meek ________________
Yoldia reagani Dall, n. nom

Phacoides acutilineatus Conrad ______________

Spisula albaria Conrad ______________________
Tellina arctata (Conrad) var.juana Reagan __
Tellina arctata (Conrad) var.juana Reagan __ D0
Tellina oregonensis Conrad __________________

Marcia oregonensis Conrad __________________

Chione securis Shumard ____________________
Antigona olympidea Reagan ________________ o
Cyclinella? sp ______________________________

Dal] (1922) This report

?Calyptraea sp.
______________ Not determined.
Sinum scopulosum (Conrad).

Bruclarkia oregonensis (Con.
rad).

Acila conradi (Meek).

Yoldia supramontereyensis
Arnold.

Glycymeris sp.

Vertipecten fucanus (Dall).

Not determined.

Vertipecten fucanus (Dall).

Lucinoma acatilineata (Con-
rad).

Spisula albaria (Conrad).

Macoma arctata (Conrad).

Tellina emacerata Conrad.

Not determined.

Katherinella angustifrons
(Conrad).

Secufiella ensifera (Dall).

Katherinella angustifrons

(Conrad).
Panopea generosa Gould ______________________ Panope abrupta Conrad ______________________ Panopea abrupta (Conrad).
Teredo sp ____________________________________ Teredo sp. indet ____________________________ Teredo sp.
Teredo bulbosus Reagan, n. sp ________________ Xylotrya? substriata Conrad ________________ Do.
Scaphopod:

Dentalium substriatum Conrad ________________

Conrad], were described as new. Dall (1922)
reexamined the specimens that Reagan (1909, pls. 1—3)
illustrated and made significant taxonomic revisions.
These are correlated with names used in this report in
table 1.

Subsequent study of other collections from the up-
permost part of Arnold’s (1906) Clallam Formation
added a few more taxa to the known fauna; Arnold and
Hannibal (1913) listed 34 species of mollusks from five
localities in the Clallam, and Weaver (1916a) listed 43
species from two localities. Neither of these, nor any of
the subsequent reports in which Clallam mollusks
have been listed (Etherington, 1931; Durham, 1944;
Moore, 1963), dealt specifically with the biostratig-
raphy of the formation or the molluscan taxonomy.

Relatively little work has been done on other kinds
of marine organisms from the Clallam Formation. A
few benthonic foraminifers have been recorded from
the Clallam by Rau (1964); these, and stratigraphic
relations, suggest assignment of the Clallam to the
Saucesian Stage of Kleinpell (1938). A marine carni-
vore was described from the Clallam Formation by
Stirton (1960) who also noted the occurrence of ceta-
cean bones and shark teeth.

Late Paleogene and Neogene provincial molluscan
stages for the Pacific Northwest States and western

Dentalium? substriatum Conrad ______________

 

Dentalium pseudonyma
Pilsbry and Sharp.

Canada were described in two reports published after
this manuscript was completed (Armentrout, 1975,
and Addicott, 1976). Unfortunately processing of this
manuscript had reached a stage where only limited
referencing of these stages was feasible following final
editing and completion of the artwork.

MOLLUSCAN FAUNA

Collections obtained during this investigation have
tripled the size of the previously known fauna of the
Clallam Formation. Among the previously unreported
mollusks are a few newly described species—
Semicassis pyshtensis, Priscofusus goweri, P. slipensis,
Ophiodermella olympicensis, and Solamen snavelyi. In
addition, six other mollusks appear to be undescribed
but are represented by poorly preserved material in-
adequate for formal description. In all, 76 molluscan
taxa are identified from the Clallam (table 2).

Taxonomically, gastropods and pelecypods are about
evenly represented in the Clallam Formation: 34 gas-
tropod and 39 pelecypod taxa. In some assemblages,
however, there may be twice as many species of
pelecypods as gastropods, and in individual collections
pelecypods usually far outnumber gastropods in num—
bers of individual specimens.

MOLLUSCAN FAUNA

TABLE 2. —Mollusks from the Clallam Formation, northern Olympic Peninsula, Wash.
[X, present as identified; cf., similar form; a112, comparable but apparently different form;, ‘? doubtful identification]

 

 

 

 

 

 

 

 

 

   

 

 

 
 

 

   

 

  

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

o o
assazssssssesssssssmsss;g
O O O Vi V‘ (D {D 50 {D to {D to {D m w 00 (D m m w v-1 v-1 v-1
v v v v <- <r v w <1 <11 <21 w <1 in If) In In no no a. p. a. a. 3 3
E E E E E E E E E E 2 E E E E S 2 2 5 Z Z Z Z D D
Gastropods:
Turritella Oregonensis (Conrad) (pl. 1, figs. 10, 11,

17 ________________________________________ H H. ._ __ H -_ H __ _- H- H ._ . __ H _- X X H H _- H H H
Epitonium clallamense Durham (Pl. 1, figs. 8,

A H x __ H __ u H H -_ __ H H H __ H H H- X __ H H __ H
Troohita n sp. Moore (pl 1, figs. 9, 12,18) X X H 7 H H X X H H X __ H H H ._ H .. H X —— X —— X -—
Crepidula4 praerupla Conrad (pl. 1, figs 1, 22; pl.

2, fig. 24) __________________________________ X X ? ._ H H H H X ._ __ H H H ._ _. X H H _H __ ? __ X H
Crepidgula princeps Conrad( 1. 1, figs. 6, 7) H.. X __ H X H H H -H __ _- ? H _. _. H -- X X H 7 -— H -- __ —-
Crepidula rostralis (Conra ) (pl. 2, figs. 23,

25 ) _______________________ H H X __ H H H _H __ H X H. __ __ __ -- H H H- __ H —7 __ __ H—
Crepidula sp. (pl 1, fig. H H - __ H H H H H H H X H - H H H H __ H H —- _. H —-
Natica cf.N. clarkiEthgerington(p1. 1, figs. 19 27,

28 _________________________________ - H H .. H H X H __ __ X H X H H H X _. _. H __ H __ __ ._
Nation uokesi Addicott (pl. 1, figs 14—16 H H X H -- H .. X H X H .. H H H H H H H -- H H H H
Neuerita jamesae Moore (pl. 1, figs 4, 5, 20,

24 ________________________________________ - H H H H H H H ._ __ H _. X H H 7 H H H H __ X __ .. _.
Palmices uctoruznus Clark and Arnold (pl 1 fig 9

2 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, H H X H H H H H H H X . __ H H __ H H H __ __ H H __ __
Sinum scopulasum (Conrad) (pl. 1, figs. 21, 26)_._ X 7 . H H H H -. H H H H H X __ H ._ X X _. H _. X ..
Semwassis pyshtensis n. sp. (pl. 1, figs. 2, 3).--. __ H . H X .. H H H H H H H H H H __ H __ __ __ H H H X
Ficus modesta (Conrad) (pl 1, figs 29, 30) .... __ _. ? __ ._ H .. X .. H H H _. .H ._ . .. H _. H H H H __ H
Trophzosycon clallamensxs (Weaver) (pl 1, fig. 31,

3 _________________________ H __ X H H H __ __ H -_ H H __ ._ __ _ __ __ H X ._ .. H H H
Trophonopsis sp (pl. 2,fi __ H . H H H X H H .H ._ H H H H H H _. ._ .. H H __ .. __
Ancistrolepis rearensis (015313) (pl. 3, fig. 26) H H _. H .. __ H H H ._ H H __ __ .. .. H H H H H H H H X _.
Bruclarkia oreganensis (Conrad) (pl. 2, figs. 1— 4,

, 19) ____________________________________ __ cf. cf. H H H __ X H .. H , __ __ __ H X __ H __ __ X H ._ H
Bruclarkia yaquinaria (Anderson and Martin) (pl.

figs.5 7— 9) ______________________________ X X X X X __ H X H H of. H X H X H ._ X H X H H ._ X ..
Molopophorus n. sp aff M. newcombei (Merriam)

(p1.2 g16) ______________________________ ._ H . __ __ H H H .. H H. __ H H X H H .. __ H __ .. H H __
Priscpfllsus aff. P. geniculus (Conrad) (pl. 2, fig.

HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH X H H H H H H. H H H H H H H- H H H __ H __ H __ -_ __ H
Priscofusus goweri, n sp. (pl. 2, figs 14, 17,18,

HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH X H _- H H X H -- __ H -_ -- H H X _. __ __ _H __ -_ X _- H H
Priscofusus slipensis, n sp. (pl. 2, fig. 13) HHHHHH .. H _. H .. ._ H H H .. H - H H H H H H H H H H H H X
Priscofusus cf. P. stewarti (Teglandg) (pl. 2, fig.

15 HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH _ X _H H H ._ H -_ -_ _. -_ H H _- __ H H H __ H H -_ H H H_ H
Musashia indurata (Conrad) (pl. 3, fig. 27) ._H . X __ H H H ._ _. H ._ H H .. ._ __ __ H .. H ? _. ._ H H- H.
Cancellaria birchi Addicott (pl. 2, figs. 36, 37)-. H _. H __ H H H .. H H H _ H cf. X H H H H H H H H ._ H
Cancellaria cf. C. oregonensis Conrad (pl. 2, figs.

28) HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH X -_ .. H -- X H H H .- A. -_ H H H H -. H ._ H -. -. H H- H
Ca2ncellaria cf. C sileizensis Hanna (pl. 2, fig

________________________________________ X H H __ __ H H H H H H __ H __ _H ._ H H __ H H H H _- H
Cancellaria cf. C. simplex Anderson (pl. 2, figs

, HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH X H H H H H H H H H H- H H __ H H H -_ H H H .- H H H
Cancellaria wynoocheensw Weaver (pl 2 figs 32

, HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH X .. __ H __ H ._ H H _H ._ H H X ._ H H _. X ._ H x H H ._
Xenuroturris antiselli (Anderson and Martin) (p1. '

2, fig. 22, pl. 3, figs. 21, 23) __ H H. _. H H H H __ H. _H X ._ H ._ __ H __ H __ _. _. H H H
Ophiodermella olympicensis, n. .(pl. 3, figs.

18—20, 22—24) _______________ H H H. X X X H X H H X H H X __ .. __ __ _. .. X _. .. ._ H ._ ._ __
?Rectiplanes sp (Mp1 2, fig. 33) _______________ X H _. H .. H _. __ H _. __ __ ._ _. H H H H _. _. .. .. __ H ._
Megasurcula cf.M . wynoocheensis (Weaver) (pl.

3,figs. 16,17) ____________________________ 7 H . H H H H -_ __ H __ . H . __ __ H H H __ H __ H H x

Scaphopods:
Dentalium pseudonyms, Pilsbry and Sharp (pl. 4,

figs 4, 8 HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH x H - H. H H H X H H __ - H __ H -. H .. __ .. __ H .. H H
Dentalium schencki Moore (pl. 5, fig 11) ______ x H X H H H H .. H X X X H H H _. H X H H __ X __ _. H

Pelecypods:
Acila conradi (Meek) (pl. 3, fi s. 1-3) HHHHHHHHHH X H X H H ? __ X .H cf. X of, ._ _ H H .. ._ H __ __ .. X _. H
Nuculana calkinsi (Moore) (p 3, figs. 4, 6, 10,

12—14 HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH X __ H _. H __ X X __ _. cf. 7 H X .. H. H X H X __ X H H H
Nucularia chehalisensis (Weaver) (pl. 3, fig.

11 ._ H H H H __ __ X H H ._ H H H H H H __ H H H __ X H ..

H -_ H -_ H H _- H ._ __ _- H H H __ H _- H X H __ H __ __ H

5) cf. H __ H H X __ .. __ X H H H __ ._ H H __ H H H H. H H H.
Archarax dalli (Clark) (pl. 3, fig. 5) -_ X __ H H __ H H H H -_ -_ H H cf. __ -- _H H x H H- -_ H --
Anadara devincta (Conrad)( 1g5, fi 3.6,10) H. __ ._ H __ __ __ ._ X ._ _. H H H __ .. __ ._ H H ._ __ _H H. H _.
Arguiara aff. A. lakei (Wie ey) (p. 5, figs 8,

) ............................... H X __ __ __ H H H -_ _. -. H __ H X H H -_ H H __ -_ -_ H -_
Glycymeris sp (pl 5, fig. 3) ...... H H .. H .. H H .. .. _. ._ __ ._ ._ H H H H _. .. H .. _.
Modiolus 11. s5p.? aff M. restorationensis Van

Winkle (p1.5 ,fig 5) ........................ H X H __ H -. H H H -H H H H -_ -_ _- H H H H __ X -_ -- H
Mytilus n. sp )aff. M. tichanovitchi Makiyama

(pl. 5, figs. 1, 2, 16, 18) .................... H __ X H '.7 H H ._ X __ _. _. H ._ __ _. ._ H H X X ? H H -_
Solamen snavelyi, 11. Sp. (pl. 4, figs 6,9) H. __ H x x H H __ __ H __ _. ._ __ _ __ H H __ __ H __ __ H H __
Vertipecten fucanus (Dall) (pl. 4, figs. 1 2

1o 12 X ? X X X H ? X H H X cf_ X X X X X H H X H X H __ H.

) cf. X - H X H ._ H H -_ H ._ ? H of __ H ._ H H H X X H H
Conchocele disjuncta Gabb(.p1 6, fig. 7). H X H _. H __ H .. H H __ H __ H X ._ H H H __ __ .. H. .. ._
Felaniella sp. (pl 5, fig ._ .. H X ._ H H _. H H .. H. ._ H H H __ _. __ __ H __ H ._ _.
Cyclocardia subtenta (Conrad) (pl. 5, fig. 12; pl.

6, figs. 9, 10 .............................. X X H H X H X H H H __ H __ H X H __ H X X H X H ._ __
Clinocardiumn. sp. aff. C. nutt—alli(Conrad)Moore

(pl. 5, fig. 13 p,1. 6, fig. 8) ___________________ X H H H H _. H H H H X H ? ._ H _H H ? H A. .H H .. H ..
Spisula albaria (Conrad) (pl 6, fig. 3; pl. 7, figs.

2, 3, 11) X H X __ X X __ X H x X __ cf. ._ X H X -. H X X X .. __ __
Spisula albaria goodspeedi Ethe

fig. 14, pl. 7, fig. 1) ........................ X __ X H X cfi H H .. cf. X cf. _. .H H H H .. __ X ._ __ H H __
Spisula cf. S. hanhibali Clark and Arnold (pl. 6,

fig. 11) .................................... X H H H H X H _- H H H -. H -- H H H H H -_ H H __ __ H

 

 

MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

TABLE 2.—Mollusks from the Clallam Formation, northern Olympic Peninsula, Wash.—Continued

 

M4049
M4050
M4051
M4413
M4414
M4675
M4677

M4678

M4679
M4680
M4681
M4683
M4684
M5878
M5879
MSH85
M5886
M6373
M6375
NP89
NP160
NI’161
Nl’163
L‘WZ']
UW490

 

Pelecypodsz—Continued

Spisula sookensis Clark and Arnold (pl. 6, figs.
1, 16 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Spisula sp. (pl. 6, fig. 6) ,,,,,,,,,,,,,,,,,,,,,,,
Solen conradi Dall (pl. 6, fig. 12) ,,,,,,,,,,,,,,
Tellina emacerata Conrad (pl. 7, figs. 5, 7, 10)_.
Macoma albaria Conrad (pl. 7, figs. 13—15, 17,
20) ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Macoma arctata (Conrad) (pl. 7, figs. 4, 6, 8, 14,
18, 22) ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Macoma astori Dall (pl. 7, figs. 9, 21) ,,,,,,,,,,
Macama sookensis Clark and Arnold (pl. 7, fig. 23;
pl. 8, figs. 1, 2, 5) ,,,,,,,,,,,,,,,,,,,,,,,,,,
Macoma n. Sp. Moore (pl. 8, fi . 4) ,,,,,,,,,,,, H
Macoma n. sp. all". M. secta (Conrad) (pl. 8, fig.
6 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Macoma cf. M. twinensis Clark (pl. 6, fig. 5)
Katherinella angustifrons (Conrad) (pl. 8, figs.

7, 8, 11~18) ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Dosinia whitneyi (Gabb) (pl. 8, figs. 9, 10) ,,,,,,
Securella ensifera (Dall) (pl. 9, figs. 1—3, 5, 6, 9,

10, 13) ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, H
Panopea abrupta (Conrad) (pl. 9, figs. 7, 8, 16) _ H
Panopea ramonensis (Clark) (pl. 9, fig. 15) ,.H H
Thracia trapezoides (Conrad) (pl. 9, figs. 4, 12) H H
Thracia cf. T. schencki Tegland (pl. 9, figs. 11,

14) ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

><><><§3,1
,‘><><

cf.

Cephalopod:
Aturia angustata (Conrad)

 

 

 

 

 

 

 

 

 

 

‘ X

X

 

xxf

X11

cf.

-¢X

cf. ><

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Most of the Clallam genera are monospecific. A few
genera, however, include several species each:
Macoma, Spisula, Crepidula, Priscofusus, and Cancel-
laria. Appreciable taxonomic diversity within these
genera is not unusual in early and middle Miocene
molluscan faunas of the middle latitudes (Loel and
Corey, 1932; Moore, 1963; Addicott, 1970b).

The generally poor preservation of shell material is
an important factor in the systematic study of the Clal-
lam molluscan fauna. Only in the silty, very fine to
fine-grained sandstones of the lowest part of the Clal-
lam Formation (fig. 3) are the aragonitic-shelled
species preserved with original shell material. The few
calcitic-shelled mollusks, such as the mytilids and the
pectinids, are preserved with shell material. They con-
stitute slightly more than 5 percent of the fauna. In
many localities, however, internal molds of both
bivalves and gastropods are preserved with fair to very
good representation of the original surface sculpture.
Most of the gastropods illustrated here are totally de-
void of shell material but nevertheless, exhibit suffi-
ciently detailed sculpture to permit confident specific
identification.

BIOSTRATIGRAPHY
INTRODUCTION

Molluscan assemblages from the Clallam Formation
are especially significant in the chronostratigraphic
classification and correlation of the lower part of the
Neogene sequence of the Pacific Northwest States. The
Clallam forms the biostratigraphic base for a recently
recognized provincial stage of early Miocene age, the
Pillarian Stage (Addicott, 1976). New biostratigraphic

 

data from the present study permitted recognition and
definition of this stage and, for the first time, determi-
nation of the boundary between it and the underlying
Juanian Stage, a unit that is coeval with the upper
parts of the so-called Blakeley Stage (Weaver and
others, 1944, chart 11) and the Matlockian Stage (Ar-
mentrout, 1975). Heretofore, there was a sizeable gap
in faunal control between the type section of the upper
part of the “Blakeley” Stage and the stratigraphically
higher molluscan assemblages of the Clallam Forma-
tion (the type section of the Echinophoria apta zone
(Durham, 1944) in the upper part of the upper member
of the Twin River Formation forms the biostrati-
graphic basis for the upper part of the "Blakeley”
Stage). Recent collections from a previously unrecog-
nized fossiliferous i‘terval of a few hundred metres
thickness at the to; of the Twin River Formation
(USGS locs. M4676, M4682, M4688, M5881, M5882,
M6374) show that the boundary between these two
lower Miocene stages, the J uanian and the Pillarian, is
at, or very close to, the contact between the Twin River
and Clallam Formations.

CLALLAM FORMATION

The Clallam Formation was described by Arnold
(1906) who included the entire stratigraphic sequence
lying above the Eocene Crescent Formation in his unit.
The name was subsequently abandoned by Arnold and
Hannibal (1913) who substituted the term Monterey
Formation for the pppermost 600 m of the post-
Crescent sequence. heir lignitic sandstone exposed
near Clallam Bay in ludes strata later assigned to the
Clallam Formation ( rown and Gower, 1958; Gower,
1960). The lower par‘ of Arnold’s (1906) Clallam For-

1
)

BIOSTRATIGRAPHY

 

FIGURE 3.—Intertidal zone exposure of Dentalium-bearing concretionary fine-grained sandstone (USGS loc. M4049) in lower part of the
Clallam Formation about 3 km west-northwest of Pillar Point.

mation has a complex nomenclatorial history (Arnold
and Hannibal, 1913; Weaver, 1937). Current usage
places the basal sandstone and conglomerate overlying
the Crescent in the Lyre Formation (Brown and others,
1956) and the stratigraphically higher sequence of ar-
gillaceous rock in the Twin River Formation (Brown
and Gower, 1958). These units have a combined
maximum thickness of about 6,300 m.

The name Clallam is here retained for strata ex-
posed between Slip Point, on the west, and Pillar Point,
on the east, in keeping with Arnold’s (1906) original
designation of strata at the very top of his formation in
this area as the type locality. As recognized here con-
glomerate and sandstone exposed between Last Creek
and Reed Creek and along the coast from the village of
Seiku westward about 5 km to the mouth of Hoko
River are reassigned to the upper member of the Twin
River Formation. The strata in the latter area were
included by Weaver (1937, p. 173) in the Clallam For-
mation. In both areas the strata contain clasts of fos-
siliferous sandstone from which an assemblage of early
Miocene mollusks referable to the Echinophoria apta

 

zone of Durham (1944) has been collected. Sandstone
at the top of the conglomerate near the mouth of Pysht
River (USGS loc’s. M4676 and M5881) contains in situ
mollusks that suggest assignment to the E. apta zone.
Molluscan assemblages from the uppermost 40 m of
the Twin River Formation (fig. 4; USGS loc’s. M4688,
M5883, and M6374) differ appreciably from the fauna
of the Clallam Formation. One species, Turritella
yaquinana Addicott, suggests correlation with rocks in
Oregon referable to the E. apta zone. Concurrent
ranges of several other species point to a provincial
early Miocene age and inclusion in the E. apta zone
even though the zonal index species does not occur in
these assemblages.

The Clallam is estimated to be as thick as 600—800 In
(Weaver, 1937; Gower, 1960). It is dominantly marine
sandstone (fig. 5), but it also contains sandy siltstone
and, locally, granule to cobble conglomerate (fig. 6).
Thin coal beds and carbonaceous siltstone exposed in a
synclinal structure near the top of the formation
(Gower, 1960) indicate nonmarine deposition. The con-
tact with the underlying sandy siltstone of the Twin

8 MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

 

FIGURE 4.—Massive, fossiliferous (USGS 10c. M4688) sandy siltstone at top of the upper member of the Twin River Formation about 2.5 km
west-northwest of Pillar Point. Base of l-m-thick sandstone at right edge of photograph marks the base of the Clallam Formation.

River Formation is conformable and gradational (fig.
7). It is well exposed on the west flank of the anticline
near Pillar Point and, also, on the east flank of the
anticline near Slip Point. There is no evidence of an
unconformity between the two formations as reported
by Weaver (1942, p. 131, 174—175). The top of the Clal-
lam is not exposed.

Folding, faulting, and penecontemporaneous defor-
mation in some segments of the coastal exposures of
the Clallam Formation make it difficult to place many
of the fossiliferous strata in stratigraphic succession
and also preclude accurate determination of the overall
thickness of the formation. Nevertheless, exposures of
the lowest 240 m of the formation on the facing flanks
of the two anticlines between Slip Point and Pillar
Point (fig. 2) are relatively undisturbed. Stratigraphic
sections (fig. 8) measured on the facing flanks of these
two structures indicate that the contact between the
Twin River Formation and the Clallam tends to be
gradational. Exposures on the east flank of the anti-
cline west of Pillar Point, however, are bounded by a
fault (Gower, 1960) and include some giant, house-size

 

rotated blocks theit preclude determination of the
stratigraphic positibn of the fossiliferous strata near
Pillar Point. The top of the measured section on the
west flank of this anticline is marked by a zone of se-
verely brecciated sandstone (fig. 3) that marks an
east-west-trending fault. To the west of this fault there
are some giant rotated blocks of sandstone (fig. 9) with
a few fossiliferous strata (USGS locs. M4679 and
M4680) of undetermined stratigraphic position. Strata
on the northwest flank of the anticline east of Slip
Point generally strike in an east-west direction and
appear to be less disturbed than strata at the east end
of the outcrop belt.

Fossiliferous strata on the east flank of the anticline
near Slip Point (USGS locs. M4414 and M4681) and on
the west flank of the anticline near Pillar Point (USGS
locs. M4050, M5879, M4049, M5878, M5885) can be
arranged stratigraphically with a considerable degree
of precision (fig. 8).

Several other assemblages seem to be from this part
of the Clallam Formation but they cannot be located
with confidence. Although the contact of the Clallam

BIOSTRATIGRAPHY 9

 

FIGURE 5.——Intertidal zone exposure of the Clallam Formation showing intensively bioturbated fine- to medium-grained marine sand-
stone overlain by finely laminated sandstone with scattered biogenic structures. Locality is about 220 m above the base of the Clallam

Formation and 3 km west-northwest of Pillar Point,

with the Twin River is not exposed on the south limb of
the overturned syncline at Slip Point (fig. 2), the
stratigraphic position of two localities there (M6029
and M4677) are estimated to be about 130 and 180 m,
respectively, above the base of the formation. The con-
tact of the Clallam with the Twin River Formation is
not exposed on the faulted north limb of the syncline at
Slip Point (fig. 2), but localities there (M4051, M4413,
and M5886) may be in the lowest 100 to 300 In of the
formation, judging by lithologic similarity to better
known sections.

The stratigraphic position of the other fossiliferous
localities cannot be determined with certainty. One of
these (M4678), however, seems to be at or near the top
of the formation judging by its position near the appar-
ent axis of the broad synclinal structure (Weaver,
1937, pl. 14; Gower, 1960) about midway between Slip
Point and Pillar Point.

In view of the structural complications, the Clallam
assemblages are placed in two broadly defined strati-

 

graphic packages based on geologic mapping by Gower
(1960). One includes the tectonically undisturbed basal
240 m of the formation that conformably overlie the
Twin River Formation; the second includes a single
locality (M4678) near the top of the formation at an
undetermined interval above the lower unit, possibly
as much as 800 m (Gower, 1960). Several localities can
be confidently placed in stratigraphic sequence in the
basal part of the Clallam (fig. 8), as previously shown,
but most cannot. Most, if not all, of these other as-
semblages, however, are similar to the material from
the lower part of the Clallam and may well represent
that part of the formation.

There is a distinct faunal hiatus between molluscan
assemblages of the upper member of the Twin River
Formation and those of the Clallam Formation. Nearly
two-thirds of the specifically determined mollusks from
the Clallam (table 3) are not known to occur in the
Twin River or in coeval early Miocene, or older, faunal
assemblages. This faunal hiatus is attributed to the

10 MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

 

FIGURE 6.—Steeply dipping conglomerate and conglomeratic sandstone lens in the Clallam Formation that form a prominent point about
2.5 km east-southeast of Slip Point. View northwest.

significantly greater taxonomic diversity of the Clal-
lam fauna, a reflection of the much warmer and shal-
lower water environment.

Several mollusks are unique to the Clallam Forma—
tion (table 4) and, for this reason, are of potential value
biostratigraphically. Among these are new species de—
scribed here as well as several taxa represented by
individual specimens, or by poorly preserved material,
that differ significantly from known species and that
probably are new. Another species that occurs in the
Clallam, and that is restricted in stratigraphic occur-
rence to coeval strata in Oregon, is Vertipecten fucanus.
This distinctive giant pectinid, which occurs in more
collections than any other species, is perhaps the most
characteristic mollusk in the Clallam. Its restricted
stratigraphic occurrence in the middle Tertiary se-
quence of coastal Oregon suggests that it can serve as a
zonal index for part of the provincial early Miocene.

The Clallam is best characterized biostratigraph-
ically by the unique co-occurrence of several species
that are also known from younger or older strata in
western Washington and western Oregon. Species that

 

appear in older stratigraphic units but that do not
range into strata younger than the Clallam include:
Archarax dalli (Clark), Spisula hannibali Clark and
Arnold, S. sookensis Clark and Arnold, Macoma
twinensis Clark, Thracia schencki Tegland, Pris-
cofusus stewarti (Tegland), and Ancistrolepis rearensis
(Clark). Many species that have their lowest occur-
rence in the Clallam also occur in stratigraphically
younger parts of the Astoria Formation of Oregon and
southwestern Washington (table 3). Others that have
their lowest occurrence in the Clallam and that range
into strata of late Miocene age or higher include: Cre-
pidula princeps Conrad, Spisula albaria goodspeedi
Etherington, and Macoma astori Dall. Some of the
species in these groups from the Clallam Formation
are doubtfully identified.

Mollusks that are characteristic of the Clallam For-
mation in terms of frequency of occurrence are given in
table 5. Most of these have a stratigraphic distribution
that is limited to the Clallam and to the middle
Miocene Astoria Formation of Oregon, as indicated in
the table. One pelecypod, Vertipecten fucanus (Dall), is

BIOSTRATIGRAPHY 1 1

 

FIGURE 7 .—Intertidal zone exposures of basal 14-m-thick fine-grained concretionary sandstone of the Clallam Formation about
2.5 km west-northwest of Pillar Point. Sandstone at right edge of photograph is 2 m thick. View southwest.

restricted to the Clallam and to the coeval late early
Miocene Nye Mudstone as well as other formations of
this age.

Analysis of the few assemblages from tectonically
.undisturbed sections in the lowest 240 m of the Clal-
lam Formation indicates certain faunal changes that
may be of local biostratigraphic significance. Several
species from the lowest parts of the Clallam do not
range into stratigraphically higher assemblages.

Collections from the basal 60 m of the Clallam (locs.
M4050 and M5879) contain several mollusks restricted
to this stratigraphic interval: Archarax dalli (Clark),
Anadara aff. A. lakei (Wiedey), Modiolus n. sp.? aff. M.
restorationensis Van Winkle, Conchocele disjuncta
Gabb, and M usashia indurata (Conrad). This collection
is from a moderately deep sublittoral assemblage, sig-
nificantly deeper than stratigraphically higher ones in
the Clallam. The absence of these species from higher
assemblages in the Clallam, together with the appear-
ance of many shallow inner sublittoral mollusks,
points to a shallowing of the depositional environment.
This change of bathymetric facies reflects the regres-

 

sive phase of an Eocene to Miocene depositional cycle
in northwestern Washington.

Faunal change in the stratigraphically higher as-
semblage from locality M4414, which is believed to be
from a somewhat higher stratigraphic position (fig. 8)
seems to reflect continued shallowing of the deposi-
tional environment. This assemblage is smaller than
that from M4050 and M5879, yet more than half of the
taxa are not represented in the stratigraphically lower
collections. It is composed principally of inner sublit-
toral bivalves that reflect the inferred shallowing of
the depositional environment. Only one species,
Semicassis pyshtensis n. sp., is restricted to this as-
semblage.

By far the largest assemblage from the Clallam is
from a stratigraphic interval about 190—210 In above
the base of the formation (locs. M4049 and M5878).
Several species are restricted to this interval:
Clinocardium n. sp. aff. C. nuttalli (Conrad) Moore,
Macoma cf. M. twinensis Clark, Priscofusus aff. P.
geniculus (Conrad), Priscofusus cf. P. stewarti (Teg-
land), Cancellaria cf. C. siletzensis Hanna, C. cf. C.

12

Pillar Point area Slip Point area

Fault

   
  
 
   
  

'.-': <—M6373
‘- }-M4049,M5878

‘7‘““4677’ South
flankof
syncline
at Slip

+?—(M6029) P°'"‘

Clallam Formation

. M4414,M4681
. . J-_- (Float in rock slide)
— . .~ }M4050,M5879

No exposures

 

Rock slide

}M6375
(From cliff west of
slide)

} M4688,M5883 —-----—

   

_____ }M6374

Upper member of the
Twin River Formation

 

EXPLANATION

Sandstone

_~j .Q'. . Concretionary
C? ..© sandstone

 

100 METR ES

  
   

- —- Silty sandstone

Sandy siltstone
and mudstone
FIGURE 8.—Stratigraphic position of fossil localities in measured sec-

tions of the Twin River and Clallam Formation near Pillar Point
and Slip Point.

O

simplex Anderson, and C. wynoocheensis Weaver. The
presence of so many seemingly restricted species is di-
rectly related to the unusually large number of species
in the assemblage. It probably also reflects the com-
mingling of mollusks from different communities, in-
asmuch as this assemblage is from layered shell ac-
cumulations possibly brought together by storm waves
whereas those from almost all of the other localities in
the Clallam consist of widely scattered mollusks depos-
ited in place.

Differences between these collections from the low-
est 200 m—those from the basal 60 In and those from
190 to 210 m—of the Clallam may prove useful in
characterization and recognition of units within the
lower part of the formation. However, because they
seem to be influenced, to a large degree, by progressive
shallowing and, perhaps, warming of the depositional
environment, regional chronologic significance cannot
be attached to them.

The small assemblage from what is believed to be

 

MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

the upper part of the Clallam Formation (loc. M4678),
about midway between Pillar Point and Slip Point, has
only three species that do not occur in collections from
the lower part of the formation. One is a poorly known
tellinid, Macoma n. sp. aff. M. secta (Conrad). Another,
a split-ribbed form of Anadara devincta (Conrad),
which occurs elsewhere in strata assigned to the Pil-
larian Stage is not, therefore, indicative of a signifi-
cantly younger age than assemblages from the lower
part of the Clallam. The third species, N uculana che-
halisensis (Weaver), is known from middle Miocene
strata in Oregon and California.

This highest collection from the Clallam is not con-
sidered to represent a distinct biostratigraphic unit, as
there is a very close similarity, if not identity, with
assemblages from the lower part of the formation. Ac-
cordingly, all the faunal assemblages from the Clallam
are here regarded as representing a single biostrati-
graphic unit, of late early Miocene provincial age, cor-
relative with the upper part of the “Vaqueros” Stage of
California.

PROVINCIAL CHRONOSTRATIGRAPHY
AGE AND CORRELATION

Molluscan specialists have generally assigned the
Clallam Formation to the provincial middle Miocene.
There is a very strong resemblance between the Clal-
lam molluscan assemblages and the well-known mid-
dle Miocene molluscan fauna of the Astoria Formation
of Oregon, a fact long evident to stratigraphers (Ar-
nold, 1906; Arnold and Hannibal, 1913; Ethering‘ton,
1931). Many species in the Clallam also occur in the
fauna of the "Temblor” Stage of central California, the
standard for the provincial middle Miocene, therefore
some specialists considered the Clallam to be coeval
with the “Temblor” Stage (Arnold and Hannibal, 1913;
Etherington, 1931; Durham, 1944; Addicott, 1969).
Until now, however, data on the Clallam fauna were so
few that correlation with the California sequence was
doubtful (Addicott, 1970a, p. 36).

The stratigraphic occurrence of several of the mol-
lusks now known from the Clallam (table 6) suggests
that the formation is of provincial early Miocene age.
These assemblages indicate correlation with the upper
part of the "Vaqueros” Stage of the California Coast
Ranges. This relation is implicit in the foraminiferal
correlations between the Clallam Formation and
California Coast Range sections based on benthonic
assemblages (Kleinpell, 1938; Rau, 1964). Still, most,
if not all, of the previous age assignments of the Clal-
lam by molluscan specialists (Etherington, 1931;
Durham, 1944; Moore, 1963; Addicott, 1967, 1969,
1970b) have been middle Miocene, or have implied a

PROVINCIAL CHRONOSTRATIGRAPHY

13

 

FIGURE 9.—Chaotic blocks of sandstone in intertidal zone exposure of
the Clallam Formation about 1 km west of triangulation station at
Pillar Point. Concretionary bed extending from lower left toward
upper right defines a west-northwest dipping block underlain by a

provincial middle Miocene age by correlation of this
fauna with the Barker’s Ranch fauna of the Temblor
Formation (Addicott, 1970a) of the San Joaquin basin,
California. And these age assignments have not dealt
directly with the disparity in correlation based on
foraminifers.

The evidence suggesting revision of the provincial
age of the Clallam is primarily from molluscan data.
Species given in table 6 suggest, in their totality, a
provincial early Miocene age. Because of doubtful
identifications of some species and limited strati-
graphic range data for others, practically all of these
mollusks cannot here be considered as index species at
this time.

Spisula sookensis, an early Miocene species from
southwestern British Columbia, is not known to occur
in strata of middle Miocene age in the Pacific North-
west. Similarly, the Oligocene and early Miocene
species Archarax dalli suggests a pre-middle Miocene
age. The doubtfully identified species, S. hannibali,

 

Thracia schencki, and Macoma twinensis are known

north-northeast dipping block in the lower right indicated by con-
cretionary lenses striking toward lower right hand corner of photo-
graph. View north.

only from the late Oligocene and early Miocene
“Blakeley” or Matlockian Stage of this region.

Two other bivalves are more diagnostic of provincial
age and correlation. M ytilus n. sp. aff. M. tichanovitchi
is known elsewhere in the eastern North Pacific only
from the early Miocene “Vaqueros” Stage of California
(Allison and Addicott, 1976). This rugose species has
sometimes been confused with the middle Miocene
index M. middendorffi (Allison and Addicott, 1976), a
species that may be its progeny. The more commonly
occurring and more Widespread pectinid, Vertipecten
fucanus, provides the strongest evidence of an early
Miocene age in terms of the mega-invertebrate se—
quence. According to J. T. Smith (oral commun., Sep-
tember 1974: UCMP loc. B1660), this species occurs in
the lower Miocene J ewett Sand of the San Joaquin ba-
sin, California, a unit that also carries lower Saucesian
benthonic foraminifers. In the Newport Embayment of
the northwestern Oregon coast, VL' fucanus appears in
the early Miocene (Addicott, 1974) and occurs strati-
graphically below Patinopecten propatulus, a wide—

14 MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

TABLE 3.—Stratigraphic ranges of species from the Clallam Formation in the Pacific Coast Tertiary
[Ranges indicated by a dotted line (. . ,) are of species not known to occur in other formations. No attempt is made to show relative stratigraphic occurrence within the Clallam. Ranges
shown for doubtfully identified mollusks (i.e., Natica cfi N. clarki) indicate the known stratigraphic occurrence of the unequivocably identified species. Pacific Northwest stages
are from Armentrout (1975) and Addicott (1976)]

 

Miocene
Series ____________________________________ Ol'

 

Lower Middle Upper

 

California molluscan stage _________________________ Unnamed "Vaqueros" "Temblor" "Margaritan"

 

 

"Blakeley"

Pillarian Newportian Wishkahan
Pacific Northwest molluscan stage _________________ Matlockian Juanian

 

 

 

Montesano
Formation of
Weaver (1912)

Formation ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, Twin RiVEr Formation, Astoria
upper member Clallam Formation
Formation

 

Pelecypods:
Acila conradi (Meek) ________________________________
Nuculana calkinsi (Moore) __________________________
N uculana chehalisensis (Weaver) ____________________
N uculana elmana Etherington ______________________
Yoldia supramontereyensis Arnold __________________
Archarax dalli (Clark) ______________________________
Anadara devincta (Clark) ___________________________

 

 

 

 

 

 

 

Anadara aff. A. lakei (Wiedey) ______________________ . . . . . . . ......
Modiolus n. sp.? aff. M. restorationensis Van Winkle _- ........ . . . . .
Mytilus n. sp. aff. M. tichanovitchi Makiyama ________
Solamen snauelyi, n. sp. ____________________________
Vertipecten fucanus (Dall) __________________________
Lucinoma acutilineata (Conrad) ______________________
Conchocele disjuncta Gabb __________________________
Feloniella parilis (Conrad) __________________________
Cyclocardia subtenta (Conrad) ______________________
Clinocardium n. sp. aft". C. nuttalli (Conrad) Moore ____
Spisula albaria (Conrad) ____________________________
Spisula albaria goodspeedi Ethering‘ton ______________
Spisula cf. S. hannibali Clark and Arnold ____________
Spisula sookensis Clark and Arnold __________________
Solen conradi Dall __________________________________
Tellina emacerata Conrad __________________________
Macoma albaria Conrad ____________________________
Macoma arctata (Conrad) ____________________________
Macoma astori Dall ________________________________
Macoma sookensis Clark and Arnold _________________
Macoma n. sp.? Moore ______________________________
Macoma n. sp. aff. M. secta (Conrad) _____-____: _____ .. . . .. . . .
Macoma cf. M. twinensis Clark ______________________
Katherinella angustifrons (Conrad) __________________
Dosinia whitneyi (Gabb) ____________________________
Securella ensifera (Dall) ____________________________
Panopea abrupta (Conrad) __________________________
Panopea ramonensis (Clark) ________________________
Thracia trapezoides (Conrad) ________________________
Thracia cf. T. schencki Tegland ______________________
Cephalopod:
Aturia angustata (Conrad)? __________________________
Gastropods:
Turritella oregonensis (Conrad) ______________________
Epitonium clallamense Durham ______________________
Trochita n. sp. Moore ________________________________
Crepidula praerupta Conrad ________________________
Crepidula princeps Conrad __________________________ ~
Crepidula rostralis (Conrad) ________________________
Natica cf. N. clarki Etherington ______________________
Natica vokesi Addicott ______________________________
Neverita jamesae Moore ____________________________
Polinices victorianus Clark and Arnold ______________
Sinum scopulosum (Conrad) ________________________
Semicassis pyshtensis, n. sp. _____________________________ . .......
Ficus modesta (Conrad) ______________________________
Trophosycon clallamensis (Weaver) ...............................
Ancistrolepis rearensis (Clark) ______________________
Bruclarkia oregonensis (Conrad) ____________________
Bruclarkia yaquinana (Anderson and Martin) ________
Molopophorus n. sp. aff. M. newcombei (Merriam) _-__ .. . . .........

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PROVINCIAL CHRONOSTRATIGRAPHY 15

TABLE 3.—Stratigraphic ranges of species from the Clallam Formation in the Pacific Coast Tertiary—Continued

 

 

 

 

 

 

 

 

Miocene
Series, ,,,. ,,,,,,,,,,,,,,,,,,, , ,,,,,,,,,, Oligocene
Lower Middle Upper
California molluscan stage ,,,,,,,,,,,,,,,,,,,,,,,,, Unnamed "Vaqueros” “Temblor” “Margaritan”
"Blakeley"
Pillarian Newportian Wishkahan
Pacific Northwest molluscan stage ,,,,,,,,,,,,,,,, Matlockian Juanian
F t’ Twin River Formation A toria Montesano
(Irma 10“ 77777777777777777777777777777777777777777 upper member l Clallam Forination Formation 0f
Formation Weaver (1912)

 

Gastropods:—Continued
Priscofusus aff. P. geniculus (Conrad) Moore __________
Priscofusus goweri, n. sp _____________________________
Priscofusus cf. P. stewarti (Tegland) __________________

 

.............

 

Priscofusus slipensis, n. sp ___________________________
M usashia indurata (Conrad) ________________________
Cancellaria birchi Addicott __________________________
Cancellaria cf. C. oregonensis Conrad ________________
Cancellaria cf. C. siletzensis Hanna __________________
Cancellaria cf. C. simplex Anderson __________________
Cancellaria wynoocheensis Weaver __________________
Xenuroturris antiselli (Anderson and Martin)
Ophiodermella olympicensis, n. sp. __________________
Megasurcula cf. M. wynoocheensis (Weaver) __________
Scaphopods:
Dentatium pseudonyma Pilsbry and Sharp ____________
Dentalium schencki Moore __________________________

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

spread species restricted to the provincial middle
Miocene. Data presented by Moore (1963, table 2) show
that these two taxa have virtually exclusive strati-
graphic distributions in the Newport Embayment. Oc-
currences of V. fucanus are in strata mapped as Nye
Mudstone (Snavely and others, 1969; 1976) whereas
those of Patinopecten are in the stratigraphically
higher Astoria Formation. At or near the Nye-Astoria
contact, however, Moore (1963, table 2, ICC. 181) does
report the two taxa from the same locality. This co-
occurrence is believed to be the transitional overlap
between the two species. The co-occurrence of these
genera in an old collection from Astoria, Oreg. (Moore,
1963, table 2, loc. 121), may represent the same situa-
tion. It is also possible that this collection includes
material from a substantial stratigraphic interval——
both the early and middle parts of the section there—

TABLE 4.—Specifically identified mollusks from the Clallam Forma-
tion that are not known to occur in other formations

 

Gastropods:
Semicassis pyshtensis, n. sp.
Trophosycon clallamensis (Weaver)
Molopophorus n. sp. aff. M. newcombei (Merriam)
Priscofusus goweri, n. sp.
Pelecypods:
Anadara aff. A. lakei (Wiedey)
Modiolus n. sp.? aff. M. restorationensis Van Winkle
Macoma n. sp. aff. M. secta (Conrad)

as the older collections from the Pacific coast com-
monly do.

The uniquely orbicular species Macoma n. sp. Moore
(1963) also occurs in the Nye Mudstone and the Clal-
lam Formation. This distribution complements the
provincial early Miocene distributions of M ytilus n. sp.
and Vertipecten fucanus.

Three gastropods are especially suggestive of pro-
vincial early Miocene age. Ancistrolepis rearensis has

TABLE 5.-—Mollusks characteristic of the Clallam Formation (species
that are identified, without doubt, from at least six collections)

[Species marked with an asterisk (*l also occur in the provincial middle Miocene fauna of
the Astoria Formation and, so far as is known, are restricted to the lower Miocene Pillar-
ian Stage and middle Miocene Newportian Stage]

 

 

Gastropods:
*Trochita n. sp.
*Bruclarkia yaquinana (Anderson and Martin)
*Ophiodermella olympicensis, n. sp.
Pelecypods:
*Nuculana calkinsi (Moore)

Vertipecten fucanus (Dall)
*Cyclocardia subtenta (Conrad)

Spisula albaria (Conrad)

Tellina emacerata Conrad
*Macoma albaria Conrad
*Katherinella angustifrons (Conrad)
*Securella ensifera (Dall)

Thracia trapezoides (Conrad)

Scaphopod:
*Dentalium schencki Moore

 

16

been previously recorded only from the late Oligocene
and early Miocene <”Blakeley” Stage [=Matlockian
Stage of Armentrout, 1975]. Priscofusus aff. P.
geniculus (Conrad) Moore is restricted to exposures of
the Nye Mudstone in coastal Oregon (as mapped by
Snavely and others, 1976) and is bracketed, strati-
graphically, by occurrences of Vertipecten fucanus
(Dall) (Moore, 1963, table 2). Its occurrence strati-
graphically below the Patinopecten propatulus as-
semblages of the middle Miocene Astoria Formation is
likewise suggestive of provincial early Miocene age.
Molopophorus n. sp. aff. M. newcombei seems to form a
phylogenetic link between the early middle Miocene
M. matthewi Etherington and the early Miocene
species M. newcombei. It is suggestive, therefore, of a
provincial late early Miocene age. Another gastropod
that is doubtfully identified because of poor preserva-
tion, Priscofusus cf. P. stewarti, may be identical to a
species known only from the provincial early Miocene
of the Pacific Northwest.

Long-range correlation with central and southern
California based on benthonic foraminifers (Rau, 1964)
substantiates a late early Miocene provincial age for
the basal part of the Clallam Formation in terms of the
California sequence. The boundary between the
Zemorrian and Saucesian stages is at, or very close to,
the contact between the Twin River Formation and the
overlying Clallam Formation (Rau, 1964); the basal
part of the Clallam is presumably of early Saucesian
age inasmuch as there is no indication of a depositional
hiatus between the two formations (fig. 3 and Gower,
1960). This microfaunal boundary, as discussed by Ad-
dicott (1973, 1974), falls within the lower Miocene
"Vaqueros” Stage of the California provincial mega-
invertebrate chronology; in California the lower part of
the Saucesian Stage is equivalent to the upper part of
the “Vaqueros” Stage. The “Vaqueros” Stage is based
on tropical and subtropical species restricted to
California and more southerly latitudes during the
early Miocene. In the Pacific Northwest, the early
Miocene is represented by the cooler water molluscan
assemblages of the J uanian Stage [=upper part of the
“Blakeley” or Matlockian Stage] and the overlying
fauna of the Pillarian Stage, represented by the Clal-
lam Formation and the Nye Mudstone.

Although the discrepancy between mollusks and
foraminifers in provincial age classification of the Clal-
lam Formation—early Miocene versus middle
Miocene—has long been apparent, it seems to have
been disregarded, perhaps because of the reported un-
conformity at the base of the Clallam and the alleged
erosion of more than 600 m of the upper member of the
Twin River Formation (Weaver, 1937, p. 175; Weaver
and others, 1944). This supposed unconformity has

 

MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

been regarded, at least by some specialists (Weaver
and others, 1944), as representing the missing early
Miocene “Vaqueros” Stage. It is shown by Durham
(1944, fig. 7) as a faunal hiatus between the two forma-
tions. In actuality, data considered here show that as-
semblages from the basal part of the Clallam are
coeval with the fauna of the early Miocene “Vaqueros”
Stage of California as are those from the uppermost
part of the Twin River Formation (Addicott, 1967).
These assemblages are not, as previously maintained
(Durham, 1944; Addicott, 1969), coeval with the mid-
dle Miocene fauna of the “Temblor” Stage. There is,
therefore, no faunal disconformity or hiatus between
the two formations as is clearly implied by the con-
formable and gradational lithologic contact first re-
ported by Gower (1960).

Correlation of the Clallam Formation with other key
sequences on the Pacific coast is shown in figure 10. Of
note is the evidence for assignment of the Astoria For-
mation of the Newport Embayment, Oreg., t0 the pro-
vincial middle Miocene. Howe (1926), Moore (1963),
and Addicott (in Snavely and others, 1964) have corre-
lated the Astoria molluscan fauna with the middle
Miocene “Temblor” Stage of California. Foraminiferal
studies support this correlation. Rau (in Snavely and
others, 1964) has shown that benthonic foraminifers
from the Astoria Formation and the Nye Mudstone
which unconformably underlies the Astoria Formation
in the Newport Embayment are of Saucesian age. The
Astoria can be referred to the upper part of the Sauce-
sian Stage on the basis of the reported occurrence of
upper Saucesian foraminifers in the upper part of the
underlying Nye Mudstone by Heacock and Boyd
(1954). According to Rau (in Snavely and others, 1964)
it may also contain assemblages of Relizian age. Pre-
sumably most of the Nye Mudstone, including the
localities from which distinctive pre-middle Miocene
assemblages containing Vertipecten fucanus have been

TABLE 6.—Mollusks from the Clallam Formation suggestive of a pro-
vincial early Miocene age

 

Pelecypods:
Archarax dalli (Clark)
Macoma cf. M. twinensis Clark
Macoma n. sp. Moore
Mytilus n. sp. aff. M. tichanovitchi Makiyama
Spisula sookensis Clark and Arnold
Spisula cf. S. hannibali Clark and Arnold
Thracia cf. T. schencki Tegland
Vertipecten fucanus (Dall)

Gastropods:
Ancistrolepis rearensis (Clark)
Epitanium clallamense Durham
Molopophorus n. Sp. aff. M. newcombei (Merriam)
Priscofusus aff. P. geniculus (Conrad) Moore
Priscofusus cf. P. stewarti (Tegland)

 

PROVINCIAL CHRONOSTRATIGRAPHY

17

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Benthonic California Pacific Northwest Northern Southwestern Newport Embayment, Gull of Alaska
Provincial foraminiferal molluscan molluscan Olympic Mountains Washington Oregon Yakataga District
series Stage (W Stag: th Stage Washington (Wolfe and McKee, 1972; (Snavalv and others, (Kanno, 1971; Miller,
(Kleinpell,1938) ”4:13:20: 1:72) (Addicott,1976) (This report) Ran, 1967) 19693.1974) 1971)
Luisian(?) and
. Relizian
Middle -+ ------ . Astoria Yakataga
. "Temblor" New ortian .
Miocene p Formation Formation
S . Astoria
. 1 I
aucestan Formation
. . Clallam Nye
Pillarian .
Formation Mudstone
Lower
Miocene '1 "
Vaqueros Upper part of
Y uina Poul»Creek
Juanian aq . Formation
Formation
Upper member of Upper part of
Zemorrian Twin River Lincoln Creek
Formation Formation
lJPDGI' Unnamed Matlockianuor Upper part ”1
Oligocene Blakeley Alsea Formation

 

 

 

 

 

FIGURE 10.—Correlation of the Clallam Formation with other sequences in the Pacific Northwest States and the provincial marine
chronologies.

collected, are of early \ Saucesian age. Elsewhere in
Oregon and in southwestern Washington (fig. 10) the
lower part of the Astoria Formation is of provincial
early Miocene age.

The fauna of the Clallam Formation may be coeval
with molluscan assemblages from the upper part of the
Poul Creek Formation at the head of the Gulf of
Alaska. The percentage of species in common with the
Poul Creek is small (Kanno, 1971, table 4), perhaps
because of the much cooler water aspect of the Alaskan
early Miocene fauna. Collections from the uppermost
200 m of the Poul Creek Formation in a measured sec-
tion at Cape Yakataga (Kanno, 1971) contain meager
assemblages with few stratigraphically distinctive
species. One of these, however, Ancistrolepis rearensis
(Clark), is restricted to the lower Miocene of north-
western Washington. Two mollusks that are restricted
to the Pillarian Stage represented by the Clallam
Formation and its molluscan fauna do occur in the
upper part of the Poul Creek, but their stratigraphic
position within that interval is not known. These
species are Vertipecten fucanus [V. sp. Kanno (1971)]
and Epitonium clallamense Durham. Mollusks that do
not range into post-early Miocene strata in Oregon and
Washington and correlative strata in California,
Aturia, M usashia weaveri (Tegland), Thracia schencki
Tegland, and Acila gettysburgensis (Reagan), also
occur in the upper part of the Poul Creek Formation
(Kanno, 1971; MacNeil, in Miller, 1971). Elsewhere in
the lower and upper parts of the Poul Creek, Liracassis

 

apta (Tegland), a species restricted to the Juanian
Stage—the lower part of the lower Miocene of Oregon
and Washington, has been recorded from several
localities (see Kanno, 1971).

Close to two-thirds of the mollusks from the Clallam
also occur in the middle Miocene part of the Astoria
Formation—the Newportian Stage—0r are rep-
resented by closely allied, possibly conspecific, taxa
(table 3). Several Clallam species, however, are re-
stricted to formations of provincial early Miocene age
in addition to many others whose concurrent strati-
graphic ranges, or position in an inferred evolutionary
sequence, are indicative of a pre-middle Miocene age.
The strong similarity between the late early Miocene
(Pillarian) fauna of the Clallam and the younger mid-
dle Miocene (Newportian) fauna of the Astoria Forma-
tion is not unique among middle latitude early and
middle Miocene faunas of the eastern North Pacific.
The faunas of the lower Miocene "Vaqueros” and the
middle Miocene “Temblor” Stages of California also
have many species in common. Consequently, differ-
entiation between these California stages is difficult.
In comparison with middle Miocene faunas, the early
Miocene faunas of both the “Vaqueros” and the Clal-
lam Formation are characterized by a much lower level
of taxonomic diversity. This relation further compli-
cates recognition and differentiation of provincial
early Miocene faunal assemblages.

In summary, reevaluation of the provincial age of
the Clallam Formation, based principally on new

18

faunal data and further analysis of the stratigraphic
ranges of key species in other Pacific coast sequences,
suggests that the molluscan assemblages of the Clal-
1am Formation are of early Miocene rather than mid-
dle Miocene provincial age. They represent the later
part of the provincial early Miocene and are readily
separable from the fauna of the J uanian Stage and the
coordinate upper parts of the “Blakeley” and Matlock-
ian Stages [Echinophoria apta Zone of Durham (1944)].
They form the faunal basis for the recently named Pil-
larian Stage (Addicott, 1976). Benthonic foraminiferal
correlations with the provincial microfaunal standard
sections in California (Kleinpell, 1938; Rau, 1964)
support this reassignment.

PILLARIAN STAGE

The Clallam Formation has been designated the
type section for the Pillarian Stage (Addicott, 1976).
This stage, which represents the upper part of the
lower Miocene of Oregon and Washington (fig. 10), is
represented by the fauna of the Nye Mudstone of the
Newport Embayment, the lower part of the Astoria
Formation in the type area near Astoria, Greg, and in
the Grays River quadrangle and possibly other areas
in southwestern Washington, and the Hoh rock as-
semblage (Rau, 1973) of the western margin of the
Olympic Mountains, Wash. The Pillarian is equivalent
to the upper part of the so-called Vaqueros Stage (see
Addicott, 1972) of the California Coast Ranges.

PALEOECOLOGY
BATHYMETRY

All the molluscan assemblages from the Clallam
Formation represent inner sublittoral depths (less
than 100 m). Qualitative analysis of assemblages from
the tectonically undisturbed sections in the lower part
of the Clallam Formation (fig. 8) points to a gradual
shallowing of the depositional environment. This trend
is an extension of the shallowing of depositional envi-
ronments in the upper part of the Twin River Forma-
tion indicated by benthonic foraminiferal assemblages
(Rau, 1964). This shoaling is the concluding phase of
an Eocene to Miocene depositional cycle in which
maximum deepening took place during the Oligocene.
Elsewhere in western Washington the concluding
phase of the transgressive-regressive cycle is rep-
resented by the middle Miocene part of the Astoria
Formation (Rau, 1967, p. 25; Wagner, 1967).

The stratigraphically lowest assemblage from the
Clallam (10c. M6375) consists of a few taxa suggestive
of deposition in the middle part of the sublittoral zone.
Most of these species also occur in the much larger, and
more environmentally definitive, collections from a

 

MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

7 -m interval nearly 60 m above the base of the Clallam
(locs. M4050 and M5879). Modern depth ranges of gen-
era and species composing this assemblage suggest dep-
osition in the middle to lower parts of the inner sub-
littoral zone—possibly 50—75 m. Species composing
this assemblage occur as isolated individuals, presum-
ably in place. The bivalves are articulated. The as-
semblage is moderately large for the Clallam—25
species—but considerably smaller than a stratigraphi-
cally higher assemblage of current or storm wave de-
posited mollusks that occurs about 130 m stratigraphi-
cally higher in the section (loc. M4049).

The basal assemblage from the Clallam contains a
few living species of moderately deep inner sublittoral
aspect: Conchocele disjuncta Gabb, Panopea abrupta
(Conrad), and Thracia trapezoides (Conrad). Available
data on the depth ranges of these species in the modern
eastern North Pacific indicate an overlap in the inter-
val between 18 and 75 m (Kanno, 1970; unpub. data
from Rae Baxter [Thracia] and Lynn Glover
[Panopea]). Other mollusks characteristic of moderate
depths in the sublittoral zone, but that extend down-
ward well into the bathyal zone, include Archarax,
Lucinoma, Solamen, and M usashia. Collectively, these
mollusks suggest that water depths were in the lower
part of the interval indicated by living species—
probably no shallower than 50—7 5 m. Archarax lives at
depths greater than about 110 m off the eastern North
Pacific coast today. M usashia is locally extinct but is
represented by species that live at depths of 100 m or
greater off the coast of Japan (Habe, 1964). The other
genera are suggestive of somewhat shallower water
conditions in terms of their known depth ranges. Sol-
amen ranges from about 30 m into the upper bathyal
zone (Soot-Ryen, 1955) along the Pacific coast, and
Lucinoma annulata (Reeve), a homologue of the
Oligocene and Miocene species L. acutilineata, ranges
from about 15 m (Smith and Gordon, 1948) to bathyal
depths (Parker, 1963) in the eastern North Pacific.

The outer sublittoral environment suggested by
modern bathymetric data for M usashia and Archarax
seems anomalously deep for this assemblage in that
many of the other mollusks are of inner sublittoral
aspect. For this reason, it is inferred that during the
early Miocene these two genera were living at some-
what shallower depths than they are now found and
that they were not restricted, as indicated by their
modern bathymetric occurrences, to the outer part of
the sublittoral zone or greater depths.

A somewhat higher assemblage from the east flank
of the anticline near Slip Point (loc. M4414) records
shallowing to depths in the middle to upper part of the
inner sublittoral zone. Most of the species in it also
occur in the collections from the lowest 55 m of the

PALE OECOLOGY

Clallam, but there are none of the deeper water indi-
cators. Among the mollusks not found in stratigraphi-
cally lower collections, Mytilus n. sp. aff. M.
tichanovitchi Makiyama is probably the most signifi-
cant bathymetric index. Mytilus is characteristic of
shallow inner sublittoral to intertidal depths along the
eastern North Pacific coast today. It is of fairly com-
mon occurrence in this and other localities in the lower
300 m of the Clallam, but does not occur in the lowest
55 In of the formation. The appearance of Dosinia is
also suggestive of shallower water conditions as well as
probable increase in marine water temperature in
terms of its modern distribution in the eastern North
Pacific (Keen, 1971).

By far the largest assemblage (locs. M4049 and
M5878) in the lower part of the Clallam Formation is
from intertidal zone exposures on the west flank of the
anticline near Pillar Point about 190—210 In above the
base of the formation (fig. 8). Fossils in this assemblage
occur as layered concentrations whereas stratigraphi—
cally lower fossils occur as isolated individuals, appar-
ently in place. The larger size of the assemblage from
localities M4049 and M5878 may well be due to the
mode of formation as current or storm wave concentra-
tions; the assemblage may include specimens from
more than one community.

The size of the assemblage from localities M4049 and
M5878 permits qualitative comparison with the mod-
erately large assemblage from near the base of the
Clallam (loc. M4050). It is interesting to note that none
of the deeper sublittoral genera and species from the
lowest assemblage (M4050) reappear in this one, par-
ticularly in View of the fact that this assemblage may
include representatives from more than one biotope.
There are several mollusks that do not occur in strati-
graphically lower collections. And these are suggestive
of inner sublittoral depths appreciably shallower than
near the base of the Clallam—possibly from about 15
to 35 m. Shallow inner sublittoral depths are suggested
by the occurrence of Clinocardium n. sp. aff. C. nuttalli,
Yoldia supramontereyensis, and the abundance and
diversity of mactrids comparable to species living at
depths of less than 35 m along the Pacific coast (Smith
and Gordon, 1948; Quayle, 1973). An upper limit of
about 15 to 20 m for the large assemblage from M4049
and M5878 is indicated by mollusks that are either
still living today or are closely related and perhaps
ancestral to living species: Thracia trapezoides,
Lucinoma acutilineata [L. annulata], Megasurcula cf.
M. wynoocheensis [Megasurcula spp.], and Macoma cf.
M. astori [M. brota].

A smaller assemblage from about 110 m above the
base of the Clallam (10c. M4681 and NP163) does not
differ significantly in taxonomic composition from

 

19

M4049. It consists mostly of bivalves suggestive of
shallow inner sublittoral depths comparable to the 15-
to 35-m range inferred for locality M4049.

The collection believed to be from near the top of the
Clallam Formation (10c. M4678), on the basis of its
location near the center of the synclinal structure be-
tween Pillar Point and Slip Point (see Gower, 1960),
has only three mollusks that are not recorded from
stratigraphically lower assemblages. One of these, a
tellinid resembling the modern species Macoma secta
which is an intertidal and upper inner sublittoral
species (Coan, 1971), may be of bathymetric signifi-
cance. However, the only‘ suggestion that this part of
the section may be of appreciably shallower bathymet-
ric facies than the lowest part of the Clallam comes
from faunal data of Arnold and Hannibal (1913). They
list a species of Anadara as the sole mollusk from a
locality (NP162) at the Clallam coal mine which is
within a few hundred metres, geographically, of local-
ity M4683, and presumably at, or near the top of, the
Clallam Formation. The occurrence of this bivalve,
without any other mollusks, may be indicative of ex-
tremely shallow water, possibly intertidal, conditions
inasmuch as Anadara in the northern part of its mod-
ern geographic distribution off Mexico today is charac-
teristic of low taxonomic diversity assemblages from
lagoonal and mangrove swamp environments (Parker,
1963; Keen, 1971).

PALEOCLIMATE

Most of the still-living molluscan genera from the
Clallam Formation are found today in temperate mid-
dle latitudes along the Pacific coast. None of the genera
are restricted to cooler, more northern latitudes, but a
few are found living in warm temperate to subtropical
latitudes far to the south of western Washington. The
appreciable representation of warm-water taxa in the
Clallam assemblages suggests that water tempera-
tures were significantly warmer at this latitude than
they are today. The warm-water gastropods are Troch-
ita, Natica, Neverita, Ficus, Semicassis, and Cancel-
laria. Some species of Cancellaria are referable to the
warm-water subgenus Euclia (Addicott, 1970a). Only
two of the pelecypods are of warm-water aspect—
Anadara and Dosinia. Both of these may have lived in
cooler water assemblages during the middle and late
Tertiary than they are found in today (Addicott, 1970b;
Stanton and Dodd, 1970; Kern, 1973). By and large all
of these warm-water taxa are limited to only one or two
assemblages, and within these assemblages they are of
relatively rare occurrence. This kind of occurrence
suggests that they were not particularly characteristic
of the Clallam assemblages and introduces the possi-
bility of seasonal recruitment from warmer water

20

populations living to the south of the fossil localities
(Addicott, 1966a, p. 14—15; Zinsmeister, 1974).

It seems doubtful that temperatures were as warm
as would be indicated by a strict application of modern
occurrences of the tropical to subtropical genera
Trochita, Cancellaria (Euclia), Ficus, Dosinia, and
Anadara s.s. that have their northernmost latitudinal
occurrences in, or close to, the modern Surian mollus—
can province (Valentine, 1966) today, a biographic unit
situated off the west coast of southern Baja California,
Mexico. Strict uniformitarian interpretation seems
especially inappropriate because two of these taxa
seem to have changed their temperature tolerance
since the middle or late Tertiary during which time
they occurred with relatively cooler water as-

semblages. Moreover, the apparent lack of large popu- '

lations of these warm-water genera suggests possible
seasonal recruitment from warmer, more southern
latitudes. Nevertheless, this element of distinctly
warm-water taxa does argue for at least cycles of water
temperature appreciably warmer than occur at this
latitude today and, there are no data suggesting cooler
water conditions.

In view of the reclassification of the age of the Clal-
lam fauna from provincial middle Miocene to late early
Miocene, the paleoclimatic diagram for the middle and
late Tertiary of northwestern Washington (Addicott,
1969) needs to be modified so as to position the Clallam
data in the uppermost part of the “Vaqueros” Stage
rather than in the overlying “Temblor” Stage. This
change remains consistent with the inferred early
Oligocene to middle Miocene warming trend in the
middle latitudes of the eastern North Pacific (Addicott,
1969). Although the faunas of the Sooke and the Clal-
lam Formations are now believed to be of early
Miocene age, they are not coeval. The apparent warm—
ing that occurred from the time of deposition of the
Sooke to the time of deposition of the Clallam is merely
condensed into a shorter period.

Neither the warm-temperate aspect of the molluscan
assemblages inferred from modern distributions of
component genera nor the apparent warming of the
shallow inner sublittoral marine environment during
the early Miocene seem to be indicated by benthonic
foraminiferal assemblages. Rau (1964) infers continu-
ing cool-water conditions during the progressive shal-
lowing of the bathymetric environment that took place
during deposition of the upper member of the Twin
River and the overlying Clallam Formation. The dif-
ferent interpretations based on the two kinds of
benthic organisms seems perplexing, but it may be no
more than an indication of a very shallow thermocline
below which water temperature remained fairly con-
stant but above which shallow inner sublittoral waters

 

MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

become progressively warmer during the late
Oligocene and early Miocene.

MOLLUSCAN PALEONTOLOGY

The molluscan fauna of the Clallam Formation con-
sists of 76 taxa identified from collections made by the
writer and from fairly extensive Stanford University
collections made by Harold Hannibal (Arnold and
Hannibal, 1913) more than 60 years ago. Conventional
systematic description of these mollusks is dispensed
with in favor of taxonomic notes indicating significant
morphologic features that either typify a taxon or dis-
tinguish it from similar species. Many of the taxa have
been treated in Moore’s (1963) monograph of the As-
toria Formation of Oregon. Others were considered in a
study of the California early and middle Miocene by
Addicott (1970a). Where pertinent, synonyms not con-
sidered in Moore (1963) or Durham (1944) are noted
and discussed. Original descriptions of previously
named taxa identified here are referenced in the
taxonomic notes.

Newly described species and other species that ap-
pear to be undescribed but that are represented by
material inadequate for formal description are treated
more thoroughly (table 7).

Practically all the mollusks from localities in the
Clallam Formation are illustrated. Also illustrated are
some of Reagan’s (1909) specimens (table 1) from the
Clallam that were originally figured by line drawings,
most of which are crudely drawn and extremely dif-
ficult to relate to actual fossil material.

The systematic flow is patterned after the familial
classification of gastropods by Taylor and Sohl (1962)
and of bivalves by McCormick and Moore (1969) that is
based on the earlier classification of Newell (1965). The
check list of species from the Clallam Formation (table
2) is arranged in the same sequence and may be used

TABLE 7.-—New species of mollusks described here and other species
believed to be new but represented by material that is inadequate for
formal description

 

Gastropods:
Trochita n. sp.
Semicassis pyshtensis n. sp.
Molopophorus n. sp. aff. M. newcombei (Merriam)
Priscofusus goweri, n. sp.
Priscofusus slipensis, n. sp.
Ophiodermella olympicensis, n. sp.
Pelecypods:
Modiolus n. sp.? aff. M. restorationensis Van Winkle
Mytilus n. sp. aff. M. tichanovitchi Makiyama
Solamen snavelyi, n. sp.
Macoma n. sp.? Moore
Macoma n. sp. aff. M. secta (Conrad)

 

GASTROPODS

as a generalized index for locating taxonomic notes in
this section.

GASTROPODS
TURRITELLIDAE

Turritella oregonensis (Conrad, 1849) [pl. 1, figs. 10,
11, 17]. Specimens of this small Turritella occur in
localities near the top of a measured section on the
west flank of the anticline near Pillar Point. They have
a pair of strong primary spirals in the anterior part of
the whorls and a single strong primary spiral rib in the
posterior part (pl. 1, figs. 11, 17). This sculptural pat-
tern is different from other figured specimens of this
species (Merriam, 1941, pl. 20, figs. 17, 19, 20; Moore,
1963, pl. 1, figs. 9—12; Addicott, 1970a, pl. 2, fig. 15), all
of which have clearly differentiated pairs of primary
and secondary spiral ribs. Nevertheless, Moore (1963,
p. 25) states that "Above the paired spirals may be 1 or
occasionally 2 secondary spirals” indicating that three
rather than four ribs may be the more common pat-
tern. Accordingly, the Clallam specimens are iden-
tified as T. oregonensis rather than as a new species.

In the Newport Embayment of northwestern Ore-
gon, Turritella oregonensis occurs in the upper part of
the Nye Mudstone (USGS loc. 15965) and in the As-
toria Formation. These are indicative of an early to
middle Miocene provincial range.

EPITONIIDAE

Epitonium clallamense Durham (1937) [pl 1, figs. 8,
13]. Specimens from locality M4413 near Slip Point
have 9 axial ribs, falling within the range of 8 to 10
ribs described by Durham (1937, p. 491, pl. 56, figs. 27,
28). The types of this species are from the east end of
Clallam Bay (Addicott, 1970a, p. 74), presumably from
the lower part of the Clallam Formation because re-
connaissance study of this area indicates that strata
referable to the Clallam are exposed during the lowest
seasonal tides. This species also occurs in an old collec-
tion from exposures immediately east of Slip Point (SU
loc. NP89), very close to the broadly defined type local-
ity. This species is restricted to the Clallam Formation
in northwestern Washington. It occurs in the presum-
ably coeval faunas of the Jewett Sand in central
California (Addicott, 1970a) and the upper part of the
Poul Creek Formation of the Gulf of Alaska (Kanno,
1971). Its earliest occurrence is in the lower Miocene
Sooke Formation of Vancouver Island (Addicott,
1970a) and not in probable middle Oligocene strata as
initially reported (Durham, 1937, p. 491).

CALYPTRAEIDAE

Trochita n. sp. [pl. 1, figs. 9, 12, 18]. One of the most
commonly occurring gastropods in the Clallam Forma-

 

21

tion is a moderately coarse ribbed calyptraeid (pl. 1,
figs. 12, 18) that is conspecific with a poorly known
taxon from the Astoria Formation of Oregon, Trochita?
n. sp.? Moore (1963, p. 26, pl. 1, fig. 23). In profile,
specimens vary from nearly smooth to slightly shoul-
dered. This is clearly an undescribed species but the
specimens from the Clallam and the known specimens
from coastal Oregon (Moore, 1963) and southwestern
Washington (Wolfe and McKee, 1972) are too poorly
preserved to adequately determine surficial sculpture
and permit formal description. Trochita n. sp. resem-
bles, somewhat, the modern tropical eastern Pacific
species T. spirata (Forbes) and T. trochiformis (Born).
Trochita n. sp. is much flatter and, although all avail-
able specimens are decorticated to varying degrees, the
spiral sculpture is much more subdued. An early
Miocene species T. sookensis (Clark and Arnold, 1923,
p. 168, pl. 36, figs. 1 and 2) from the southwestern coast
of Vancouver Island is distinguished from Trochita n.
sp. by its finer and more numerous radiating ribs. The
spire of T. sookensis species is of variable height;
specimens from USGS locality M4060 are very low
spired, comparable in this respect to Trochita n. sp.
Another poorly preserved early Miocene species from
California, Trochita cf. T. spirata (Forbes) (Addicott,
1970a, p. 61-62), has coarser spiral sculpture than
Trochita n. sp. and is unusually strongly shouldered.
The common Miocene and Pliocene species T. filosa
(Gabb, 1866, p. 15, pl. 2, figs. 25, 25a) has extremely
fine spiral ribs, at least three times as many as
Trochita n. sp.

Crepidula praerupta Conrad (1849) [p]. 1, figs. 1, 22;
pl. 2, fig. 24]. This species, occurring in several collec—
tions from the Clallam Formation, is externally simi-
lar to C. princeps Conrad, with which it occurs in the
Clallam, but the internal septum is different. The ex-
ternal morphology of these two species is so variable,
that it cannot always be used to distinguish them. On
specimens of C . praerupta the insertions of the internal
septum are approximately equidistant from the beak
(pl. 1, fig. 1) whereas on C. princeps the edge of the
septum defines a broadly open “S” and the insertions of
the septum are at unequal distances from the beak (pl.
1, fig. 7). Crepidula praerupta ranges from the early
Miocene (Loel and Corey, 1932; Kanno, 1971) to the
late Miocene (Moore, 1963).

Crepidula princeps Conrad (1855) [pl. 1, figs. 6, 7]. A
few deformed specimens of this moderately large Cre-
pidula occur in the Clallam. The strongly curved septal
margin of this species (pl. 1, fig. 7) is one of the most
distinctive specific characters. Crepidula princeps
ranges from the early Miocene to the Pleistocene along
the Pacific coast (Addicott, 1970a, p. 64). This is the
first record of C. princeps from the Pacific Northwest

22

States. A moderately large, suborbicular Crepidula
from the Sooke Formation of southwestern Vancouver
Island, British Columbia, Canada (USGS 10c. M4060),
has the same septal configuration as C. princeps; it
may represent this species, but the weakly inflated,
suborbicular shell and the blunt apex suggest that it is
a distinct species, possibly C. sookensis Clark and
Arnold.

Crepidula rostralis (Conrad, 1865) [pl. 2, figs. 23, 25].
The Clallam record of this species constitutes another
range extension; it was previously known only from
provincial middle Miocene strata (Addicott, 1970a).
The illustrated specimen is deformed, as are most of
the specimens of Crepidula from the Clallam. It is
slender and elongate during the early stages of growth;
the flattening is inferred to have been caused by sub-
sequent deformation. This specimen has the pointed
beak overhanging, or extending beyond, the aperture;
this beak is characteristic of C. rostralis and enables
this species to be readily differentiated from other
species.

Crepidula sp. [pl. 1, fig. 23]. A small Crepidula with
an orbicular aperture and a very high, more or less
vertically oriented beak. It seems to be distinct from
other species in the Clallam Formation. The septal in-
sertions are almost opposite each other. Since this is a
very small, presumably immature, specimen, it could
be an aberrant form of one of the other Clallam
species—C. praerupta—which has similar septal inser-
tions.

NATICIDAE

Natica cf. N. clarki Etherington (1931) [pl. 1, figs. 19,
27, 28]. A few small naticids from the Clallam resem-
ble the early and middle Miocene species N. clarki
Etherington (1931, p. 93, pl. 12, fig. 12). These speci-
mens have a well—developed, fairly broad umbilical cal-
lus that is unlike the callus on the holotype but com-
parable to the calluses of other specimens included in
this species by Marincovich (1973, p. 235—236).

Natica vokesi Addicott (1966b) [pl. 1, figs. 14—16].
This is the most common naticid in the Clallam.
Specimens have a slender umbilical callus reflecting a
broad, but indistinct, funicular rib comparable to type
material from Oregon (Addicott, 1966b, p. 638—639, pl.
77, figs. 2—5). Many of the large, undetermined naticids
from localities in the Clallam probably are this species,
but the preservation is too poor to permit specific iden-
tification.

Neverita jamesae Moore (1963) [pl. 1, figs. 4, 5, 20,
24]. A poorly preserved specimen (pl. 1, fig. 24) from
USGS 10c. M4684 has the widely open umbilicus, small
bilobed callus, and broad apical angle characteristic of
this species (Moore, 1963, p. 28—29, pl. 2, figs. 5, 15, 19).

 

MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

This species was identified by Arnold and Hannibal
(1913, p. 588, 10c. NP161) as “Polinices saxea Conrad.”
P. saxea Conrad is a doubtful species that cannot be
recognized because the type material is lost and the
original description and illustration are vague (Moore,
1963, p. 28).

Polinices victorianus Clark and Arnold (1923) [pl. 1,
fig. 25]. This early to middle Miocene species is known
from only two localities in the Clallam. It is charac-
terized by a narrow umbilical opening with a distinct,
somewhat enlarged umbilical callus (Clark and Ar-
nold, 1923, p. 170, pl. 33, figs. 1 and 5). As is the case
with the other Clallam naticids, it may be represented
by poorly preserved, specifically indeterminate mate-
rial in other Clallam collections.

Sinum scopulosum (Conrad, 1849) [pl. 1, figs. 21, 26].
Specimens of this long-ranging naticid are generally
preserved as internal molds. Often the fine spiral
sculpture is imprinted on these steinkerns (pl. 1, fig.
21).

CASSIDIDAE
Semicassis pyshtensis, n. sp.

Plate 1, figures 2, 3

This fairly well-preserved cassidid has a low spire
consisting of about four whorls; the penultimate whorl
has prominent protractive axial ribs that are stronger
than the straplike spiral ribs. These axial ribs are very
subdued on the body whorl tending to be replaced by
very faint irregular lines of growth. Spiral sculpture on
the body whorl consists of 15 straplike ribs that are
strongest toward the base. These are separated by fine
secondary spirals. The face of the body whorl im-
mediately adjacent to the aperture was covered by an
apparently thin callus, a part of which is preserved on
the fossa and on the base of the whorl.

The holotype (USNM 215928) is from USGS locality
M4414. It is 42 mm high and 28 mm wide.

Semicassis pyshtensis differs from other middle and
late Tertiary species from Oregon and Washington
principally by its unique rib count. It is most similar to
S. aequisulcatum (Dall, 1909, p. 63—64, pl. 5, figs. 1, 4),
a late Miocene species from Oregon and southwestern
Washington but differs from S. aequisulcatum in hav-
ing 15 rather than 19 spirals. S. pyshtensis seems to
form an evolutionary link between this finely
sculptured late Tertiary species and the coarsely
ribbed Oligocene species S. iani (Schenck, 1926, p. 80,
pl. 13, figs. 8—11) which has only 11 spiral bands on the
body whorl. ,

S. aequisulcatum and S. iani were previously as-
signed to Phalium (Schenck, 1926, Weaver, 1942).
Morphologically they are much closer to species of

GASTROPODS

Semicassis from Japan. The Japanese species have a
very thin parietal callus that is smooth except for spi-
ral plaits near the base of the apertural margin (Habe,
1964, p. 69—70, pl. 21). The Japanese species are from
the inner sublittoral zone, 10—100 m. Semicassis pysh-
tensis differs from the modern 8. centiquadrata (Valen-
ciennes), a very shallow water species from the Pan-
amic molluscan province (Keen, 1971, p. 501, fig. 949),
in lacking a granulated or pustulose callus surface.

FICIDAE

Ficus modesta (Conrad, 1848) [pl. 1 figs. 29, 30]. This
bulbous, finely sculptured species is definitely known
from only one of the collections studied during this
investigation. Mature specimens reach a moderately
large size and are smooth except for spiral sculpture of
alternating fine and ultrafine ribs crossed by fine axial
lines of growth. The intersection of these axial and
spiral systems produces a finely reticulate network.
The relatively smooth exterior of this species permits
differentiation from the coarsely noded Trophosycon
clallamensis (Weaver) (pl. 1, fig. 31) which also occurs
in the Clallam Formation. Ficus modesta occurs in the
middle Miocene part of the Astoria Formation of

southwestern Washington (Etherington, 1931; Ad-'

dicott in Wolfe and McKee, 1972) and coastal Oregon
(Moore, 1963).

Trophosycon clallamensis (Weaver, 1912) [pl. 1, fig.
31; pl. 2, fig. 34]. A small specimen with an unusually
broad body whorl and broad apical angle was collected
from near Slip Point (USGS loc. M4051). It has two
prominent rows of nodes and a few relatively strong
spiral ribs. These features distinguish it from Ficus
modesta which is doubtfully recorded from the same
locality. Trophosycon clallamensis resembles the wide-
spread early Miocene to Pliocene species T. kernianum
(Cooper), but it differs from T. kernianum in having a
broader body whorl and weak, vertically elongated
nodes (Addicott, 1970a, p. 75).

MURICIDAE

Trophonopsis sp. [pl. 2, fig. 20]. An incomplete ex-
ternal mold of the body whorl of a minute gastropod
from loc. M4677 near Slip Point has well-preserved
sculpture characteristic of Trophonopsis. The body
whorl is angulated a short distance below the suture,
the somewhat sinuous axial ribs are bladelike, and
there is a long anterior canal. This may be the earliest
record of the muricid genus along the Pacific coast. The
earliest previous record seems to be from the late
Miocene of the Cuyama Valley area of the central
California Coast Ranges (Eaton and others, 1941, pl. 2,
fig. 4).

 

23

NEPTUNEIDAE

Ancistrolepis rearensis (Clark, 1932) [pl. 3, fig. 26].
Only one specimen of this neptuneid has been collected
from the Clallam. This species is characterized by a
rounded whorl profile and a subsutural spiral rib
situated high on the body whorl. The presence of the
subsutural spiral rib distinguishes it from the presum-
ably ancestral Oligocene species, A. clarki Tegland
(1932, p. 131, pl. 12, fig. 14) on which this rib is indis-
tinct from the suture (Durham, 1944, p. 177). Ancis-
trolepis clarki teglandae Durham (1944, p. 177, pl. 17,
fig. 2) was shown by Kanno (1971, p. 118—119, pl. 13,
figs. 5, 9; pl. 14, figs. 4—6) to be a junior synonym of this
species. The occurrence of A. rearensis in the Clallam
constitutes a range extension from the early Miocene
Echinophoria apta zone of Durham (1944) from which
it was previously known in the conterminous United
States. The occurrence in the upper part of the Poul
Creek Formation presumably is coeval judging by the
co-occurrence with the “E.” apta (see Kanno, 1971).

Bruclarlcia yaquinana (Anderson and Martin, 1914)
[pl. 2, figs. 5, 7—9]. This species, the most commonly
occurring of the two species of Bruclarkia in the Clal-
lam Formation, is characterized by four, or sometimes
five, coarsely noded spiral cords on the body whorl. The
cords become progressively weaker toward the base of
the whorl. The body whorl is bordered posteriorly by a
well-developed subsutural collar on both small and
large individuals. Specimens from near the base of the
Clallam are identical to material from the lower
Miocene of the San Joaquin basin in California (Ad-
dicott, 1970a, pl. 10, figs. 8, 12, 13). As recognized here,
B. yaquinana is a small species. A large doubtfully
identified internal mold (pl. 2, fig. 5) from the vicinity
of Slip Point has very coarsely noded spiral cords simi-
lar to B. yaquinana but the cords are more widely
spaced. Since the earlier ontogenetic stages of this
specimen are not preserved, definitive comparison with
B. yaquinana cannot be made.

Bruclarkia oregonensis (Conrad, 1848) [pl 2, figs.
1—3]. This is a larger, more rounded species which dif-
fers from B. yaquinana, with which it sometimes oc-
curs, in having uniformly finer spiral sculpture
through all stages of growth. Nevertheless, differentia-
tion of the two species is sometimes very difficult.
Specimens from locality M4051, for example, seem to
link these two species. A few of these specimens are
clearly B. yaquinana (pl. 1, fig. 9). Other specimens
seem to more closely resemble B. oregonensis (pl. 2,
figs. 4, 6, 19). Still others have intermediate sculptural
characteristics. The observed stratigraphic relation be-
tween these two species in central California (Addicott,
1970a, p. 91) is not so clearly evident in northwestern

24 MOLLUSCAN PALEONTOLOGY, LOWER

Washington. It is suggested in a general way however,
by the almost exclusive occurrence of B. oreg nensis at
the top of the formation and by the decided prevalence
of specimens of B. yaquinana at, and near, the base.

Bruclarkia oregonensis is best represented by mate-
rial from near the top of the Clallam Formation (loc.
M4678). These specimens (pl. 2, figs. 1—3) are relatively
large, are weakly sculptured, and have a poorly de-
veloped subsutural collar, if' any at all. They are very
similar to specimens from the Astoria Formation of
southwestern Washington (Etherington, 1931, pl. 11,
figs. 1, 3, 4, 7).

Molopophorus n. sp. aff. M. newcombei (Merriam,
1897) [p]. 2, fig. 16]. The external mold of a
Molopophorus from the basal part of the Clallam near
Pillar Point (loc. M5879) seems to be an undescribed
species. It is most closely allied, morphologically, to M.
newcombei (Merriam, 1897, p. 65), an early Miocene
species from the Sooke Formation of nearby Vancouver
Island, British Columbia. When compared with M.
newcombei (pl. 2, figs. 10, 11), the Clallam specimen
has generally weaker sculpture with both fewer spiral
and axial ribs. Besides being weaker and more widely
spaced, the spiral ribs of M. n. sp. aff. M. newcombei
(Merriam) are obsolete on the posterior quarter of the
body whorl. This apparently new species differs from
the middle Miocene species M. matthewi Etherington
(1931, p. 97, pl. 13, figs. 3, 6, 8, 9, 13) in having a
sculptured body whorl and a well-developed subsutural
collar. Molopophorus n. sp. may possibly provide an
evolutionary link between the early Miocene M. new-
combei and the middle Miocene M. matthewi.
M olopophorus does not seem to be closely related to M.
anglonana (Anderson, 1905, p. 205, pl. 16, figs. 74—76),
an early and middle Miocene species characterized by a
flat body whorl segment bordered by a noded sub-
sutural collar and a noded basal angulation.

FUSINIDAE

Priscofusus aff. P. geniculus (Conrad) Moore (1963)
[pl. 2, fig. 12]. Two deformed and incomplete fusinids
from the lower part of the Clallam Formation appear to
be conspecific with this undescribed species of Pris-
cofusus from the Nye Mudstone (Snavely and others,
1969b, pl. 1) south of Newport, Oreg. The body whorl of
this taxon is unusually strongly angulated, and it has
a relatively long, gently inclined subsutural slope.
Available specimens are too incomplete to permit for-
mal description of this species, which appears to be
restricted to the late early Miocene of the Pacific
Northwest States.

Priscofusus goweri, n. sp.
Plate 2, figures 14, 17, 18, 21

Fairly abundant specimens of Priscofusus from

 

IOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

localities on the west flank of the anticline near Pillar
Point appear to be different from known species of this
genus. These specimens are characterized by about 15
vertically oriented axial ribs that occupy the upper
half of the body whorl. The axial ribs extend from su-
ture to suture on the penultimate whorl. The body
whorl carries about 20 fine spiral cords; secondaries
are intercalated between the uppermost of these.

The holotype (USNM 215962) is from USGS locality
M4049. It is 18 mm high and 8 mm wide. Paratypes
(USNM 215960, 215961, 215963) from this locality
range from 16 to 23 mm in height and from 8 to 12 mm
in width.

This species is named in recognition of Howard
Gower who completed the first detailed geologic map-
ping of the Clallam Formation (Gower, 1960).

This species seems closest morphologically to Pris-
cofusus clarki Kanno (1971, p. 122—123, pl. 13, fig. 8, pl.
14, figs. 8, 9, 15) from Alaska and P. stewarti (Tegland,
1933, p. 129—130, pl. 12, figs. 4—8) from Washington.
The holotype ofP. clarki (Kanno, 1971, pl. 3, fig. 8), the
only well-preserved specimen illustrated, has angu-
lated whorls unlike P. goweri and unlike Clark’s (1932,
p. 833, pl. 20, figs. 1—3) Fusinus cf. F. hannibali Clark
and Arnold, which Kanno included as a synonym of his
recently named Alaskan species. Clark’s specimens,
although poorly preserved, have a rounded whorl pro-
file and a lower rib count (see illustrations in Addicott
and others, 1971, figs. 2a, 2d—2f). Priscofusus goweri
differs from P. stewarti in having axial ribs rather than
nodes, or elongated nodes, on the shoulder of the body
whorl. Moreover, the whorls are rounded rather than
angulated in profile. The axial ribs on P. goweri are
narrower and more numerous than on P. hannibali
(Clark and Arnold, 1923, pl. 30, figs. 1, 2), an early
Miocene species from the Sooke Formation of south-
western Vancouver Island, British Columbia. It seems
most likely that Clark’s (1932) poorly preserved speci-
mens are conspecific with P. hannibali, as originally
indicated.

Priscofusus slipensis, n. sp.

Plate 2, figure 13

A well—preserved, nearly complete specimen of Pris-
cofusus from exposures near Slip Point is conspecific
with Moore’s (1963, p. 42, pl. 6, figs. 8, 11)Priscofusus
n. sp.? This species is characterized by strongly angu-
lated whorls. On the penultimate whorl, the axial ribs
extend from suture to suture; at the medial angulation,
they form a thin, spirally elongated node. On the lower
two thirds of the penultimate whorl, fine secondary
spiral cords alternate with the primary spiral cords.
The body whorl has 12 vertically oriented axial ribs

GASTROPODS

that are strongest in the central part of the whorl just
below the angulation. These ribs quickly fade out
above the angulation and do not reach the suture. Spi-
ral sculpture on the slightly concave subsutural shoul-
der consists of finely beaded primary spiral cords that
are separated by fine secondary threads of variable
strength. The same pattern continues below the angu-
lation with the infrequent addition of a tertiary spiral
thread.

The holotype (SUPTC 154049) is from University of
Washington locality 490. It is 27 mm high and 16 mm
wide.

The sculpture of Priscofusus slipensis is identical to
that of the specimen from near Spencer Creek, Lincoln
County, Oreg., described by Moore (1963, p. 42, pl. 6,
fig. 11) as Priscofusus n. sp.? This species differs from
the known species of Priscofusus from the eastern
North Pacific margin in having vertically elongated
nodes that extend across the penultimate whorl and
across the medial third of the body whorl. Its occur-
rences here and in the Astoria Formation of Oregon
define a late early Miocene to middle Miocene range.
Priscofusus hannibali (Clark and Arnold, 1923, p. 158,
pl. 30, figs. 1, 2) from the lower Miocene Sooke Forma-
tion of Vancouver Island is similar to P. slipensis but
differs in having rounded axial ribs that extend from
the suture to near the base of the body whorl.

Priscofusus cf. P. stewarti (Tegland, 1933) [pl. 2, fig.
15]. A small crushed specimen with angulated and
strongly noded whorls resembles the early Miocene
species P. stewarti from the upper Oligocene type
Blakeley Formation near Seattle, Washington. The
angulation on the body whorl is relatively close to the
suture. The angulated and strongly noded whorls dif-
ferentiate P. stewarti from P. goweri n. sp. from the
same locality. If correctly identified as P. stewarti, this
occurrence constitutes a range extension from the
upper Oligocene Echinophoria rex zone (Durham,
1944).

VOLUTIDAE

Musashia indurata (Conrad, 1849) [131. 3, fig. 27]. An
undoubted specimen of the coarsely ribbed volute,
M usashia indurata, was collected from the basal part of
the Clallam Formation near Pillar Point (loc. M4050).
The axial ribs are well developed on the spire but
weaker and irregularly spaced on the body whorl.
About 18 axial ribs occur on the last half of the penul—
timate whorl and the first half of the body whorl. This
rib count is the same as that on specimens of M. in-
durata from the Astoria Formation of Oregon (Moore,
1963, p. 43—44, pl. 7, figs. 1—9, 11; pl. 8, figs. 1—5). Faint
spiral sculpture is evident on the upper part of the body
whorl of the Clallam specimen, and the ribs show the

 

25

characteristic curvature just below the suture.
Musashia corrugata (Clark, 1932, p. 831—832, pl. 21,
figs. 4, 5, 11) from the Gulf of Alaska has fewer axial
ribs than M. indurata, about 13—15 (Kanno, 1971,
p. 125), and a much more slender shell. The Alaskan
species is reported from the Oligocene and early
Miocene (Kanno, 1971, p. 126); the earlier provincial
occurrence of M. corrugata and its morphological
similarities to M. indurata suggest that it could be the
precursor of the early to middle Miocene species.

Musashia indurata had previously been recorded
only from the provincial middle Miocene. The Clallam
record constitutes a definite range extension from the
middle Miocene into the provincial early Miocene.
M usashia indurata was doubtfully reported from the
lower Miocene of the southern San Joaquin basin on
the basis of fragmental material (Addicott, 1970a,
p. 105, pl. 13, fig. 8).

CAN CELLARIIDAE

Cancellaria birchi Addicott (1970a) [pl. 2, figs. 36,
37]. A moderately high-spired cancellariid from the
basal part of the Clallam is somewhat more spinose
than specimens from the type locality in central
California but is otherwise similar. This record of C.

‘birchi constitutes a range extension; C. birchi was pre-

viously known only from the provincial middle
Miocene of the southeastern San Joaquin basin,
California.

Cancellaria cf. C. oregonensis Conrad (1865) [131. 2,
figs. 26—28]. Poorly preserved specimens from two
localities resemble a slender, relatively high-spired
form of C. oregonensis Conrad from the Astoria Forma-
tion of Oregon (Moore, 1963, pl. 9, fig. 19). The axial
ribs on the Clallam specimens are variable and gener-
ally fewer in number than on the material from the
Astoria Formation. As with other species of Cancel-
laria from the Clallam, decortication makes species
identification difficult.

Cancellaria cf. C. siletzensis Hanna (1924) [pl. 2, fig.
29]. This doubtfully identified cancellariid is based on a
poorly preserved, deformed specimen from near the
base of the Clallam Formation. It has the fine spiral
sculpture and broadly rounded axial ribs characteristic
of C. siletzensis; heretofore, C. siletzensis has been re-
ported from the Astoria Formation of Oregon (Moore,
1963, p. 44, pl. 9, figs. 2, 5). One of the Astoria
localities, USGS locality 18901, may be from the up-
permost part of the Nye Mudstone according to recent
geologic mapping (Snavely and others, 1976) and of
provincial early Miocene age.

Cancellaria cf. C. simplex Anderson (1905) [pl. 2,
figs. 30, 31]. Decorticated specimens from USGS local-
ity M4049 near the base of the Clallam Formation

26

have widely spaced, swollen axial ribs and a relatively
large body whorl similar to the strongly sculptured
form of C. simplex Anderson of Addicott (1970a, pl. 14,
figs. 19, 20, 27), a Miocene species from central and
southern California. These doubtfully identified
specimens are much closer to C. simplex than they are
to typical C. oregonensis from the Astoria Formation. If
this doubtful occurrence could be validated by better
material, it would constitute a range extension from
the middle Miocene into the early Miocene.

Cancellaria wynoocheensis Weaver (1916b) [pl. 2,
figs. 32, 35, 38]. This is possibly the most distinctive
cancellariid in assemblages from the Clallam Forma-
tion. It is characterized by fine spiral ribbing and
numerous, closely spaced axial folds. There are consid-
erably more axial folds on this species than on C.
oregonensis with which it occurs in the Astoria Forma-
tion of Oregon and southwestern Washington. This
record is a range extension from the provincial middle
Miocene into the provincial early Miocene.

TURRIDAE

Xenuroturris antiselli (Anderson and Martin, 1914)
[pl. 2, fig. 22, pl. 3, figs. 21, 23]. A poorly preserved,
decorticated turrid from the Clallam has spiral ribbing
identical to Moore’s (1963, pl. 10, figs. 6, 12, 13, 15)
“Thesbia” antiselli (Anderson and Martin) from the
Astoria Formation of Oregon. Moore’s species was sub-
sequently included as a coarsely ribbed form of X. an-
tiselli (Anderson and Martin) by Addicott (1970a,
p. 128). This form is characterized by five coarse, strap-
like spiral ribs on the body whorl. It has been doubt-
fully recorded from the lower Miocene Jewett Sand of
the San Joaquin basin, California (Addicott, 1970a).

?Rectiplanes sp. [pl. 2, fig. 33]. The external mold of
a small, high-spired turrid seems to represent Recti-
planes. The proportions and the smoothly rounded pro-
file of the whorls are similar to late Tertiary and
Quaternary specimens from the Pacific coast. The
closest described species from the Miocene of Oregon or
Washington is Spirotropis washingtonensis
Etherington (1931, p. 113, pl. 14, figs. 8, 22, 34) from
the Astoria Formation. This species differs from ?Rec-
tiplanes sp. in having a prominent, and sometimes
noded, angulation on the body whorl and on some of
the whorls of the spire.

Ophiodermella olympicensis, n. sp.

Plate 3, figures 18—20, 22

A small turrid characterized by strongly developed
spiral ribbing is described as Ophiodermella olym-
picensis n. sp. This species has distinctive characteris-
tics and can therefore be differentiated from known

 

MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

Miocene turrids with little difficulty. It is known
mostly from internal molds which provide an incom-
plete record of details of surface sculpture. The spire is
sculptured by 4 spiral cords. Two primary spiral cords
are flanked by a weaker spiral cord at the anterior
suture and a fine spiral cord posteriorly. The rounded
body whorl has eight spiral ribs that tend to be
strongest on the medial part of the whorl. The upper-
most spiral rib varies in strength and position with
respect to the suture; sometimes it adjoins the suture
but usually it is separate. This spiral rib and the next
two spiral ribs may be separated from the lower five by
a somewhat broader interspace (pl. 3, fig. 19). On many
specimens, however, all the spiral ribs are of about
equal length and may be equidistant from each other
(pl. 3, fig. 18). The posterior notch is fairly deep and
similar in configuration to species included in the
genus by Powell (1966, p. 92).

The holotype (USNM 215992) is from USGS locality
M4051. It is 16 mm high and 6.5 mm wide. Paratypes
from this locality (USNM 215993, 215994, 215995)
range from 11.5 to 17 mm in height.

This species is assigned to Ophiodermella because of
the configuration of the posterior siphonal notch and
because the general aspect of ribbing is similar to the
Pliocene species 0. graciosana (Arnold, 1907, p. 430—
431, pl. 54, fig. 18).

Ophiodermella olympicensis differs from O. worken-
sis (Etherington, 1931, p. 111—112, pl. 14, figs. 12, 24,
26, 28, 30) from the Astoria Formation of southwestern
Washington in having a rounded, rather than flat-
tened, whorl profile and in having bolder spiral rib-
bing. Xenuroturris antiselli (Anderson and Martin) re—
sembles this species somewhat but it differs in having
an angulate body whorl with a concave profile between
the angle and the posterior suture.

Ophiodermella olympicensis is most likely to be con-
fused with 0. muirensis (Clark and Arnold, 1923,
p. 157—158, pl. 30, figs. 4—6), an older early Miocene
species from the Sooke Formation, Vancouver Island,
British Columbia. The Sooke species differs from O.
olympicensis in having more spiral ribs and in lacking
the gap between the two prominent cords on the body
whorl.

A similar and possibly related species identified as
Ophiodermella n. sp. by Addicott (in Wolfe and McKee,
1972) occurs in the Astoria Formation of the Grays
River quadrangle, southwestern Washington. This
turrid has similar spiral sculpture (pl. 3, figs. 24, 25)
but seems to differ in having a very wide interspace
between the upper two or three spirals and the lower
set of five. Because of these minor differences, it is
doubtfully included with the Clallam species as
Ophiodermella cf. 0. olympicensis. This species also oc—

PELECYPODS

curs in the nearby Raymond quadrangle (USGS 10c.
M2287) in southwestern Washington.

Megasurcula cf. M. wynoocheensis (Weaver, 1912)
[pl. 3, figs. 16, 17]. A very well preserved Megasurcula
from near Slip Point is similar to M. wynoocheensis
(Weaver, 1912, p. 70—71, pl. 9, figs. 87-89), a middle
Miocene species from the upper part of the Astoria
Formation of southwestern Washington. It resembles a
rather low-spired form of this species reillustrated by
Weaver (1942, p. 527, pl. 98, fig. 8) but it differs in
having a less concave subsutural slope. Another differ-
ence is in the much closer position of the nodes to the
posterior edge of succeeding whorl. Megasurcula cf. M.
wynoocheensis is differentiated from M. condonana
(Anderson and Martin), a Miocene species from Oregon
and California, on the basis of its much higher and less
evenly conical spire.

PELECYPODS
NUCULIDAE

Acila conradi (Meek, 1864) [pl. 3, figs. 1—3]. This
Acila is of fairly common occurrence in the Clallam
Formation. It has not been found in the stratigraphi-
cally lowest collections from the Clallam near Pillar
Point (USGS locs. M4050 and M5879). The lowest oc-
currence is in a float collection near Slip Point repre-
senting an interval from 40 to 110 m above the base of
the formation (USGS loc. M4681). This species com—
monly has a secondary bifurcation of the radial rib
pattern. Strong concentric ribbing is developed near
the ventral margin on most of the larger specimens.
This species has been recorded from many localities of
Miocene age by Schenck (1936, p. 84) including one
California early Miocene record from the Freeman Silt
of Addicott (1970a), a unit that contains foraminiferal
assemblages of early Saucesian age. A previous record
from the Hoh Formation of Schenck (1936, p. 83—84) of
the western Olympic Peninsula, Wash., represents a
second early Miocene occurrence because it occurs
there with the early Miocene index species Vertipecten
fucanus (Dall). Although this species has long been
thought to be restricted to rocks of provincial middle
Miocene age, there are at least three early Miocene
records, therefore the occurrence in the Clallam is not
a range extension.

NUCULANIDAE

Nuculana calkinsi (Moore, 1963) [pl. 3, figs. 4, 6, 10,
12—14]. This species occurs in molluscan assemblages
from the finer grained strata of the Clallam Formation.
Specimens are characterized by centrally located
beaks, strongly inflated valves, and equally spaced

 

27

ribbing. Many of the specimens are deformed, espe-
cially those from localities M4049 and M5878. Some
individuals are larger than Moore’s (1963) material
from the Nye Mudstone and the Astoria Formation of
Oregon, and others tend to be somewhat more elon-
gate.

Nuculana chehalisensis (Weaver, 1912) [pl. 3, fig.
11]. A small species previously reported from the mid-
dle Miocene of southwestern Washington, Oregon, and
central California (Etherington, 1931, p. 66) occurs in
an assemblage from what appears to be the highest
part of the Clallam Formation (USGS loc. M4678).
This nuculanid is relatively high in proportion to its
length and has a strongly concave posterior dorsal
slope. It has been compared with N. eparchis Moore
(1963, p. 55), but it differs from that species by its less
elongate valves and, also, by its coarser concentric
sculpture.

Nuculana cf. N. elmana Etherington (1931) [pl. 3,
figs. 8, 9]. Nuculanids from the lower 40 m of the Clal-
lam Formation near Slip Point resemble the moder-
ately elongate species N. elmana Etherington from the
Astoria Formation of the Grays Harbor basin, south-
western Washington. The principal difference between
them is the somewhat more pointed posterior of the
specimens from the Clallam. This taxon differs from N.
calkinsi (pl. 3, figs. 10, 12, 14) in having a long rela-
tively straight posterior dorsal slope and in lacking the
faint sinus in the anterior part of the valves.

Other nuculanids that are too poorly preserved for
specific identification occur in the collections from
localities M4050, M4414, M4681, and M4683.

Yoldia supramontereyensis Arnold (1908) [pl. 3, figs.
7, 15]. Specimens from a few localities in the Clallam
represent the initial record of this species north of the
type area inthe San Francisco Bay region of central
California. Material from locality M4680 indicates
some variation in the concavity of the posterior dorsal
slope. The beaks tend to be situated medially which
permits this species to be differentiated from the
Oligocene to middle Miocene species Y. tenuissima
Clark (1918, p. 78—79, pl. 8, figs. 5, 9). This record con-
stitutes a range extension into the provincial lower
Miocene; the holotype is from the unnamed sandstone
of Dibblee (1966) which overlies the Page Mill Basalt
that has been dated as 14.4 :24 my (Turner, 1970, p.
106). Benthonic foraminifers from this sandstone are of
provincial middle Miocene (Relizian or Luisian) age
(Clark, 1968, p. 177). Until now all records of Y. sup-
ramontereyensis were from strata of provincial middle
Miocene age (Loel and Corey, 1932).

Undetermined, poorly preserved specimens of Yoldia
from localities M4681, M4683, and M4684 may repre-
sent Y. supramontereyensis.

28
SOLEMYIDAE

Archarax dalli (Clark, 1925) [pl. 3, fig. 5]. Specimens
of Solemya from the lowermost part of the Clallam
Formation near Pillar Point (USGS loc. M4050) are
identical to probable topotypes of A. dalli from the
upper member of the Twin River Formation. The out-
line of the valves and the position of the beaks are the
same. This species is difficult to distinguish from the
middle Miocene species A. ventricosa (Conrad). Weaver
(1942) and Tegland (1933) cite the more posterior loca-
tion of the beaks on A. dalli as being the significant
specific determinant. Tegland (1933, p. 103) separated
A. ventricosa from A. dalli on the basis of two large
quadrate specimens from the upper Eocene and lower
Oligocene Keasey Formation that were later namedA.
willapaensis (Weaver, 1942, p. 21—22). According to
Weaver (1942, p. 20), the length of the anterior seg-
ment of the dorsal margin averages 75 percent of the
length of the shell onA. dalli, whereas onA. ventricosa
it averages only 60 percent. This means of differentia-
tion seems suspect because the position of the beaks on
the lectotype of A. ventricosa is about 75 percent of the
length of the dorsal margin (Moore, 1963, pl. 11, fig. 8).
Although the two species are very similar, they do
seem to differ in the outline of the valves. Specimens of
A. ventricosa, including the paratype and the lectotype
(Moore, 1963, pl. 11,”figs. 8, 11), are much higher in
proportion to their length than are specimens of A.
dalli. A. dalli is known from the upper member of the
Twin River Formation and the basal part of the Clal—
lam. A. ventricosa is not known to occur in strata older
than middle Miocene along the Pacific coast; a late
Oligocene or early Miocene record attributed to Teg-
land (1933) by Moore (1963, p. 52) is in error.

ARCIDAE

Anadara aff.A. lakei (Wiedey, 1928) [pl. 5, figs. 8, 9].
Decorticated specimens of an Anadara from the lowest
part of the Clallam Formation near Pillar Point (USGS
locs. M4050 and M5879) are similar toA. lakei, a mid-
dle Miocene species from central California. Identifica-
tion of these specimens is doubtful owing to their poor
preservation. They have about 25 ribs that are grooved
medially. ThisAnadara is similar to the late Oligocene
to early Miocene species A. submontereyana (Clark,
1918, p. 128—129, pl. 16, fig. 2) from California but has
more radial ribs—25 rather than 22 to 24. Anadara
devincta (Conrad), the common Miocene species from
the Astoria Formation of Oregon and southwestern
Washington which occurs stratigraphically higher in
the Clallam Formation, can be readily differentiated
from this species by its much higher rib count—29—32
(Reinhart, 1943, p. 44).

Anadara devincta (Conrad, 1849) [pl. 5, fig. 10]. This

 

MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

Anadara occurs in strata that appear to be near the top
of the Clallam Formation near the center of the
syncline between Pillar Point and Slip Point (Gower,
1960). This species is distinguished fromA. aff. A. lakei
(Wiedey), which occurs in the lower part of the Clallam
Formation, by having a larger number of radial ribs
about 29 rather than 25. As shown by Reinhart (1943),
the number of radial ribs is a critical specific character
in this genus. The ribs are split by two grooves in the
anterior part of the valve and by a single groove in the
medial and posterior parts (pl. 5, fig. 10). The present
specimens are identical to the split—ribbed form of A.
devincta of Moore (1963, p. 59—61) which occurs in both
the Nye Mudstone (USGS locs. 18830, 18831, 18941,
and 19050) and the Astoria Formation in the Newport
Embayment, Oreg.

GLYCYMERIDIDAE

Glycymeris sp. [pl. 5, fig. 3]. Specifically indetermi-
nate internal molds of Glycymeris occur at two
localities (M4414 and M4684) in the Clallam F orma-
tion. The genus has not previously been recorded from
this formation nor has it been found in the upper
member of the Twin River Formation.

MYTILIDAE

Modiolus n. sp.? aff. M. restorationensis Van
Winkle (1918) [pl. 5, fig. 5]. A rather small Modiolus
with weakly inflated valves occurs in the lowermost
part of the Clallam Formation (locs. M4050 and
NP161). It is similar to M. restorationensis Van
Winkle, a late Oligocene species from western
Washington, but differs in having a convex, rather
than straight or concave, dorsal margin and a less
broadly flattened extremity. These differences suggest
that it is an undescribed species, but there are too few
specimens to rule out the possibility that it might be a
form of M. restorationensis.

Mytilus n. sp. aff. M. tichanovitchi Makiyama
(1934) [pl. 5, figs. 1, 2, 16, 18]. An undescribed rugose
mytilid from the Clallam Formation resembles Mytilus
tichanovitchi Makiyama (1934, p. 134—135, pl. 5, figs.
11, 12) from the Miocene of Hokkaido, Japan (pl. 5, fig.
14), and M. ochotensis (Slodkewtisch, 1938, p. 117, pl.
49, fig. 4, pl. 50, fig. 1), presumably a synonym of M.
tichanovitchi from the Miocene of Kamchatka. The
Clallam species has strongly inflated valves character-
ized by a broad umbonal angle, a flared dorsal margin,
and a strong umbonal ridge together with a secondary
ridge occupying the posterior part of the depression
between the ridge and the dorsal wing (pl. 5, figs. 1, 2).
The dorsal alation on specimens from the Clallam is of
variable strength owing, in part, to deformation of

PELECYPODS

most of the specimens. The secondary ridge distin-
guishes the Clallam species from M. tichanovitchi. As
noted by Allison and Addicott (1976), this Mytilus n.
sp. also occurs in strata of provincial early Miocene age
in central California and in strata of early middle
Miocene age (Gladenkov, 1974) in western Kam-
chatka. The California occurrence is based on speci-
mens from the southern San Joaquin basin that have
been confused with M. middendorffi Grewingk (Ad—
dicott, 1965). Although the two species resemble each
other superficially, the margins of the valves of M ytilus
n. sp. are straight whereas those of M. middendorffi
fold sinuously. The Kamchatka record is based on
specimens figured by Il’ina (1963, pl. 11, figs. 1, 6) from
the Kuluven Suite, possibly erroneously, as M.
ochotensis Slodkewtisch and on an additional specimen
from the same unit figured by Allison and Addicott
(1976, pl. 2, figs. 2, 5).

Solamen snavelyi, n. sp.
Plate 4, figures 6, 9

Previously undescribed elongate, strongly inflated
specimens of Solamen similar to the Oligocene species
S. porterensis (Weaver, 1912, pl. 14, fig. 116) are here
named S. snavelyi. The elongate-ovate valves of this
species are sculptured by 100 or more fine flat-topped
ribs. In the medial part of the valve, these ribs are
separated by very narrow interspaces. Near the an-
terior margin, the radial ribs are much finer and the
interspaces are relatively wider. Irregularly spaced
concentric growth lines, some of which are strongly
constricted, occur at increasingly closely spaced inter-
vals toward the ventral margin.

The holotype (USNM 216008) is from USGS locality
M4051. It is 14 mm long and 21 mm high. A paratype
(USNM 216007) from USGS locality M4050 is 14 mm
long and 19 mm high.

Solamen porterensis, an Oligocene species from
Washington, differs from S. snavelyi in having bifur-
cating radial ribs and more quadrate valves as indi-
cated by a topotype (pl. 4, figs. 3, 11) from Porter Bluffs,
Wash. Crenella cf. C. porterensis Weaver (Moore, 1963,
p. 63, pl. 15, fig. 6) from the Astoria Formation of Ore-
gon seems to belong to S. porterensis in view of its
similar shape and pattern of bifurcating ribs. If so, it
represents a range extension from the Oligocene “Lin-
coln” Stage and the lower part of the Matlockian or
“Blakeley” Stage (Durham, 1944) to the provincial
middle Miocene.

Solamen snavelyi also occurs in the Astoria Forma—
tion of southwestern Washington (Addicott in Wolfe
and McKee, 1972, table 13, as Crenella cf. C. porteren-

 

29

sis Weaver). The provincial range of this species is
from the early Miocene to the middle Miocene.

This species is named for Parke D. Snavely, Jr., in
recognition of his contributions toward deciphering the
geological history of western Oregon and Washington.

PECTINIDAE

Vertipecten fucanus (Dall, 1900) [pl. 4, figs. 1, 2, 5, 7,
10, 12]. This pectinid is the most characteristic mollusk
in assemblages from the Clallam Formation. It is usu-
ally represented by disassociated valves, complicating,
somewhat, differentiation from fragmental specimens
of the somewhat similar giant pectinid, Patinopecten
propatulus (Conrad), a middle Miocene species from
the Pacific Coast. The left valves of these species are
distinct but the ribbing of the right valves, as noted by
Moore (1963, p. 65), is similar. There are, however,
important morphological differences between the right
valves of these two giant pectinids that have not been
previously considered. The ears of V. fucanus, for
example, are relatively much larger than those of P.
propatulus. Specifically, the length of the ears on
specimens of V. fucanus is considerably more than half
the width of the valves whereas on P. propatulus the
ears are less than half the width of the valves. A second
difference is the initially flat or slightly concave profile
of right valves of V. fucanus during early growth
stages. This profile contrasts with the regularly convex
profile of P. propatulus. In adult specimens of V.
fucanus, the initially flat profile of V. fucanus usually
develops into a gently convex profile similar to that of
P. propatulus. Finally, the ribbing on right valves of V.
fucanus is much more irregular than on P. propatulus,
especially in the lateral areas. Many specimens of V.
fucanus have one or more irregular ribs in the medial
part of the disk and most specimens have a widening
and deepening of the medial interrib corresponding to
the strongly raised opposing rib of the left valve.

Some earlier workers (Arnold and Hannibal, 1913;
Arnold, 1906; and Weaver, 1916a) identified both of
these large pectinids in assemblages from the Clallam.
Study of available collections reinforces the apparent
conclusion of later investigators (Etherington, 1931;
Durham, 1944) that there is only one large pectinid, V.
fucanus, in the Clallam. All the left valves examined
are referable to V. fucanus because of the characteris-
tic pattern of a strongly raised medial rib and some-
what less accentuated flanking ribs that divide the
disk into quadrants. These valves also differ from those
of P. propatulus in being much more convex.

Specimens in the collections average about 80—90
mm in greatest diameter. These averages are mislead-
ing because the relatively small specimens are easiest
to collect. In the field, most specimens exceed 100 mm

30 MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

in maximum diameter, and there are several speci-
mens in the stratigraphic collections that are as large
as 110—120 mm. The right valves have 17 or 18 some-
what irregular flat-topped ribs. This valve also has a
reticulate, or honeycombed, microsculpture that covers
both the ribs and the interspaces. There are usually 15
or 16 crested ribs on the left valves; the medial rib is
much stronger than any of the others and most are
scaly or imbricated. Both valves have fine, irregular
lateral ribs.

As indicated elsewhere in the text, Vertipecten
fucanus seems to be a very useful species in biostrati-
graphic correlation of Miocene formations in the
Pacific Northwest States. Its restricted stratigraphic
occurrence in the Nye Mudstone of western Oregon
and the J ewett Sand of central California is indicative
of provincial early Miocene age. It also occurs in the
Hoh rock assemblage of Rau (1973) along the western
side of the Olympic Peninsula, Wash. (10c. M4146) with
shallow-water mollusks that also occur in the Clallam
and are presumably coeval.

LUCINIDAE

Lucinoma acutilineata (Conrad, 1849) [pl. 5, figs. 4, 7,
15]. Scattered and usually poorly preserved specimens
of this lucinid occur in some parts of the Clallam For-
mation. As is characteristic of this species, the density
of concentric lamellae is variable, but the spacing is
equidistant over the greater part, if not all, of the
valves (Moore, 1963, p. 70). This species is almost al-
ways preserved with articulated valves. It ranges from
the middle part of the provincial Oligocene (Hickman,
1969) to the middle Miocene (Addicott, 1973). It is
difficult to distinguish this species from some of the
late Oligocene specimens from the Blakeley Formation
of Washington figured as L. hannibali (Clark) by Teg-
land (1933, pl. 8, figs. 10, 12). The holotype ofL. hanni-
bali (Clark, 1925, pl. 22, figs. 2, 4) differs from L.
acutilineata in having less regularly rounded valves
and much more anteriorly situated beaks. The early
Miocene species L. columbiana (Clark and Arnold,
1923, p. 144—145, pl. 25, fig. 2) that is from the Sooke
Formation of Vancouver Island may be a synonym of L.
acutilineata.

THYASIRIDAE

Conchocele disjuncta Gabb (1869) [pl. 6, fig. 7]. The
essentially straight anterior margin of this species
permits differentiation from the similar Tertiary
species C. bisecta (Conrad) which has a concave an-
terior margin and more prominent umbones (Bernard,
1972). Many Cenozoic molluscan specialists have con-
sidered C. disjuncta to be a junior synonym of C.
bisecta (see, for example, discussions in Moore, 1963,

 

and Bernard, 1972). Although C. disjuncta is some-
times treated as a deep-water taxon, a modern north-
eastern Pacific occurrence from only 10 m was de-
scribed by Kanno (1971). Conchocele disjuncta occurs
in collections from the lowest part of the Clallam For-
mation.

UNGULINIDAE

Felam'ella sp. [pl. 5, fig. 17]. The outline of a small
bivalve from locality M4413 is suggestive of Felaniella,
a fairly common genus in Oligocene and Miocene
faunas from the Pacific Coast States. Felaniella parilis
(Conrad) was reported from Slip Point, about a mile
west of locality M4413, by Etherington (1931, checklist
facing p. 31).

CARDITIDAE

Cyclocardia subtenta (Conrad, 1849) [pl. 5, fig. 12; pl.
6, figs. 9, 10]. Specimens from the Clallam have about
22 radial ribs that become narrower toward the pos-
terior part of the valve. The outline of the valves is
variable and the beaks usually are prominent. Cyclo-
cardia castor (Dall, 1909, p. 116, pl. 11, figs. 1, 3) from
the upper member of the Twin River Formation, on the
east side of the mouth of East Twin River, has a similar
rib count and valve outline. It may well be a synonym
of C. subtenta, but according to Weaver (1942, p. 139—
140) it differs in having a more deeply impressed
lunule and weaker but broader radial ribs. Cyclocardia
yakatagensis (Clark) from the upper part of the Poul
Creek Formation, Gulf of Alaska, may also be a
synonym of this species. It has a similar rib count,
23—25 radial ribs. The form named by Dall (1909, p.
115) as “Venericardia subtenta var. quadrata” from
specimens collected near Slip Point in the vicinity of
USGS locality M4413 (“one mile east of Clallam Bay”)
was differentiated from C. subtenta on the basis of its
larger, more quadrate valves. Dall’s taxon, however,
falls within the range of variation of C. subtenta
(Moore, 1963, p. 70).

CARDIIDAE

Clinocardium n. sp. aff. C. nuttalli (Conrad, 1837) [pl.
5, fig. 13; pl. 6, fig. 8]. A few poorly preserved cardiids
from the Clallam Formation may represent an unde—
scribed species. Although decorticated, specimens of
Clinocardium n. sp. appear to have had at least 18
coarse ribs anterior of the posterior inflection. The ribs
on one specimen (pl. 5, fig. 13) are broad and rather flat
topped. The other specimens are decorticated to such
an extent that the original rib configuration cannot be
determined. The beaks are inclined as in other species
of Clinocardium. In all probability, this is the same

PELECYPODS

species as Moore’s (1963, p. 73, pl. 30, figs. 1, 2)
Clinocardium aff. C. nuttalli (Conrad) from Coos Bay,
Oreg. Clinocardium yakatagense (Clark, 1932, p. 813,
pl. 18, fig. 8), a somewhat similar species from the mid—
dle Miocene part of the Yakataga Formation, Gulf of
Alaska, has a similar rib count but differs at least from
the best preserved specimen of Clinocardium n. sp.
from the Clallam (pl. 5, fig. 13) in having crested
rather than broadly rounded, or flat-topped, ribs. The
other specimens from the Clallam are too poorly pre-
served to permit confident distinction from other mid-
dle Tertiary species. An early Miocene cardiid from the
Sooke Formation of Vancouver Island, British Colum-
bia, C. sookensis (Clark and Arnold, 1923, p. 145, pl.
22, figs. 1 and 2), differs from Clinocardium n. sp. in
having almost twice as many radial ribs.

MACTRIDAE

Spisula albaria (Conrad, 1848) [pl. 6, fig. 3; pl. 7, figs.
2, 3, 11]. This moderately large mactrid is charac-
terized by a concave anterior dorsal slope, a convex
posterior dorsal slope, and prominent beaks that tend
to be situated posterior to the midline of the valves.
The anterior extremity is pointed; the posterior ex-
tremity is much broader. Moore (1963, p. 82—83, pl. 28,
figs. 1—3, 5; pl. 31, figs. 9, 11) assigned all mactrids
from the Astoria Formation of Oregon to this species,
recognizing a broad range of variation in the outline of
the valves. Reagan’s (1909, p. 187, pl. 2, fig. 19) Mactra
gibbsana Meek (pl. 7, figs. 2, 3) is a synonym of this
species as originally noted by Dall (1922). The anterior
part of the specimen is deformed. This species is one of
the most commonly occurring and abundant bivalves
in the Clallam Formation. It is easily differentiated
from other Spisula from the Clallam by its characteris-
tic elongate-trigonal valves.

Spisula albaria goodspeedi Etherington (1931) [pl. 6,
fig. 14; pl. 7, fig. 1]. This nearly equilateral trigonal
mactrid was described from the upper Miocene Mon-
tesano Formation of Weaver (1912) of southwestern
Washington. The unique outline of the valves permit
differentiation from S. albaria, but in the context of the
broad range of variation recognized by Moore (1963, p.
82—83), it would very likely be treated as only a form of
the latter species. This species also occurs in the mid-
dle Miocene part of the Astoria Formation of south-
western Washington (Etherington, 1931).

Spisula cf. S. hannibali Clark and Arnold (1923) [pl.
6, fig. 11]. This mactrid has an unusually broad apical
angle and long, more or less straight, dorsal slopes. It
is represented by poorly preserved material, con-
sequently the identification is doubtful. Spisula han-
nibali has been reported from strata of provincial early
Miocene age near Seattle that are correlated with the

 

31

upper part of the "Blakeley” Stage (Durham, 1944).
The principal difference between S. hannibali and both
S. albaria and S. albaria goodspeedi is the unusually
broad apical angle. As in the case of S. albaria
goodspeedi, it seems possible that this taxon could fall
within the broad range of variation of S. albaria recog-
nized by Moore (1963, p. 82—83) although it was not
included as a synonym of that species. Spisula
equilateralis (Clark, 1932, p. 819—820, pl. 11, fig. 8), an
early Miocene species from the upper part of the Poul
Creek Formation, Gulf of Alaska (Kanno, 1971, p. 72),
may be a synonym of S. hannibali but appears to differ
in having relatively longer valves.

Spisula sookensis Clark and Arnold (1923) [pl. 6, figs.
1, 16]. Another Spisula originally described from the
lower Miocene Sooke Formation of nearby Vancouver
Island, Canada, occurs at a few localities in the Clal-
lam. It is a large, thin-shelled mactrid similar in out-
line to the Miocene-to-Holocene species S. catilliformis
(Conrad) (Packard, 1916, pl. 18, figs. 1, 2; Fitch, 1953,
fig. 53). Both Spisula sookensis and S. catilliformis
have a rib just below the posterior dorsal margin, but
S. sookensis differs from S. catilliformis in having more
quadrate valves with the beaks situated closer to the
anterior extremity. It seems possible that some
Miocene records of S. catilliformis from California
(Loel and Corey, 1932, p. 170, 232, pl. 44, fig. 8; Pack-
ard, 1916, p. 286, pl. 9, figs. 1, 2) could be of this
species. If so, a provincial early Miocene (Vaqueros
Formation of Loel and Corey, 1932) to late Miocene
(San Pablo Group of Clark, 1915) age would be indi-
cated.

Spisula sp. [p]. 6, fig. 6]. A specimen from locality
M4049 is so different from the other species in the Clal-
lam that it is treated, tentatively, as a separate taxon.
It is most similar to S. albaria, but the outline of the
valves differs from this commonly occurring species in
the anterior location of the beaks.

SOLENIDAE

Solen conradi Dall (1900) [pl. 6, fig. 12]. A small Solen
with a slightly convex ventral margin and a straight or
slightly concave dorsal margin is conspecific with S.
conradi Dall (1900, p. 953), a species originally de-
scribed from the Astoria Formation of Oregon. The few
specimens from the Clallam are from the lowest 240 m
of the formation. Solen conradi ranges from the early
Miocene to the middle Miocene (Moore, 1963).

TELLINIDAE

Tellina emacerata Conrad (1849) [pl. 7, figs. 5, 7, 10].
This is the most commonly occurring tellinid in the
Clallam Formation. It can be readily differentiated

32

from the other Clallam tellinids by the prominent, in—
clined internal rib in the anterior half of the valve (pl.
7, figs. 5, 10). This feature is apparent on most of the
Clallam specimens because practically all lack shell
material. The plane of commissure is flexed posteriorly
resulting in a slight bending of the valves. The surface
is sculptured by very fine, evenly spaced concentric
grooves. Reagan’s (1909, p. 186—187, pl. 2, fig. 18) T.
clallamensis is a synonym of this species; it is refigured
on plate 7, figure 10. Tellina emacerata ranges from the
early Miocene to the middle Miocene in Oregon and
Washington. It may be represented by Tellina (Oudar—
dia) sp. Kanno (1971, p. 75—76, pl. 10, figs. 4, 5) from
the upper part of the Poul Creek Formation in the Gulf
of Alaska region. In California, this species ranges
from the late Oligocene to the late Miocene (Addicott,
1973, p. 32).

Macoma albaria Conrad (1849) [pl. 7, figs. 13—15, 17,
20]. This small tellinid, characterized by posteriorly
located beaks and valves that are weakly flexed poste-
riorly, occurs at a few localities in the Clallam Forma-
tion. Almost all the right valves of this species have
been bored by gastropods. The right valve is the more
strongly flexed of the two valves. The flexing and the
position of the borings near the middle of the right
valve suggest that this species lived very close to the
surface and that the plane of commissure was oriented
parallel to the sediment-water interface with the right
valve above the left one. This species and two other
small Macomas from Oligocene and Miocene forma-
tions in Oregon and Washington, M. twinensis Clark
and M. arnoldi Tegland, are very similar. Both M. al-
baria and M. twinensis Clark (1925, p. 96, pl. 12, fig. 7)
have posteriorly located beaks and are much less
strongly flexed posteriorly. As an alternative to dis-
crimination as separate species, it seems possible that
the two taxa could be treated as forms of a variable
species. Macoma arnoldi Tegland (1933, p. 119—120, pl.
9, figs. 2—8), a small species of late Oligocene age, dif-
fers from these two in having higher, more trigonal
shaped valves and more centrally located beaks (pl. 7,
figs. 16, 19). Reagan’s (1909, pl. 2, fig. 15) M. albaria
could be M. arnoldi; as noted by Moore (1963, p. 50) it
is not M. albaria.

Macoma arctata (Conrad, 1849) [pl. 7, figs. 4, 6, 8, 14,
18, 22]. The elongate valves of this large species are
bent or flexed posteriorly as in the late Cenozoic
species M. nasuta (Conrad); the. left valve is more
strongly flexed than the right one. The beaks are lo-
cated in the posterior part of the valve. Some speci-
mens (pl. 7, figs. 8, 14), preserved with shell material
or as internal molds, have faint radial ribbing in the
anterior ventral part. Some of the best specimens are
from locality M4051; the shell material has been

 

MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

leached but the exterior sculpture has been transferred
to the internal molds and is fairly well preserved. This
probably is the type locality for Reagan’s (1909, p. 186,
pl. 1, fig. 17) Tellina arctata var. juana. The holotype of
this taxon is refigured on plate 7, figure 14. Specimens
from near the base of the Clallam (10c. M4049) may
represent the earliest occurrence of large species of
Macoma in Oregon and Washington. Material iden-
tified as M. arctata from the uppermost part of the Lin-
coln Creek Formation (Armentrout, 1975) could be
coeval; the associated assemblage contains only a few
species, none of which are diagnostic of provincial age.
This species appears in the provincial late Oligocene in
California (Addicott, 1973, p. 33). Its highest strati—
graphic occurrence in California, Oregon, Washington,
and Alaska (Moore, 1963; Kanno, 1971; Addicott,
1973) is in strata of middle Miocene age. This species
also occurs in the western North Pacific where it has
the same geological range. The oldest record is from
the late Oligocene 0f Honshu Island, Japan (Kanno,
1960); the youngest (Il’ina, 1963, p. 81) from middle
Miocene (Gladenkov, 1972, p. 169) strata of Kam-
chatka, Russia.

Macoma cf. M. twinensis Clark (1925) [pl. 6, fig. 5]. A
few, small articulated tellinids from the Clallam For-
mation are doubtfully identified as Macoma twinensis.
They are more elongate and have more centrally lo-
cated beaks than the more commonly occurring speci-
mens of Macoma albaria Conrad. Macoma twinensis
was described from exposures of the upper member of
the Twin River Formation about 2 miles west of Twin
River (Weaver, 1942, p. 210). This species also differs
from M. albaria in having more strongly flexed valves.
Specimens of M. twinensis from near the base of the
type section of Durham’s (1944) Echinophoria apta
zone (loc. M4032) are illustrated on plate 6 (figs. 2, 4,
13, 15) and plate 7 (fig. 12). Identification of this
species in the Clallam is doubtful because of the simi-
larity to M. albaria and because the valves are not so
strongly flexed as on undoubted specimens of M.
twinensis. The latter condition could be due to defor-
mation of the valves. Macoma twinensis ranges from
the provincial late Oligocene to the early Miocene. The
doubtful record of this species in the Clallam is the
youngest in the Pacific Coast Tertiary.

Macoma astori Dall (1909) [pl. 7, fig. 21]. Significant
morphologic features of this taxon are its pointed and
relatively strongly flexed posterior extremity, its long
and nearly straight posterior dorsal margin, and its
almost medially located beaks. One moderately large
specimen from the Clallam (pl. 7, fig. 21) is almost
identical to Dall’s type specimen (see Moore, 1963, p.
81, pl. 29, fig. 12). Macoma astori seems to be more
similar to the late Tertiary and Quaternary species M.

PELECYPODS

nasuta (Conrad) than to any of the other bent-nosed
Oligocene and Miocene species from Oregon and
Washington. Some paleontologists (Grant and Gale,
1931, p. 369; Faustman, 1964, p. 22; Talmadge, 1972,
p. 413) consider M. lipara Dall (1916), a Pliocene to
Holocene species, to be indistinguishable from M. as-
tori and, by inference, a synonym of this species. This
treatment seems inadvisable in view of longer, and
straight rather than convex, posterior dorsal margin of
M. astori. Moreover, the right valve of M. astori is
much more strongly flexed than that of M. lipara.

Macoma sookensis Clark and Arnold (1923) [pl. 7, fig.
23; pl. 8, figs. 1, 2, 5]. Left valves ofa large, fairly thick
shelled Macoma from the lowest 40—110 m of the Clal-
lam Formation (USGS locs. M4681 and NP161) are
identical to Clark and Arnold’s (1923) species from
nearby Vancouver Island, British Columbia. This
species is similar to M. nasuta (Conrad), a commonly
occurring modern taxon that ranges back into the
Miocene. Like M. nasuta it has anteriorly located
beaks and a ligamental nymph indicative of an elon-
gate ligament. The overall shape of the valves is simi-
lar, but the valves of these specimens of M. sookensis
are less strongly flexed and are broadly rounded,
rather than pointed, posteriorly. This rounding plus
the less strongly sloping posterior dorsal margin give
the valves of this species a more quadrate outline than
M. nasuta. Macoma sookensis seems to be restricted to
strata of provincial early Miocene age.

Macoma n. sp. aff. M. secta (Conrad, 1837) [pl. 8, fig.
6]. A single specimen of an incomplete internal mold of
a right valve, somewhat similar to Macoma secta, may
represent an undescribed species. It is referred to the
subgenus Rexithaerus because of the flange developed
along the posterior dorsal margin. It differs from M.
secta in being more elongate and in having a broadly
truncate posterior margin. This taxon also differs from
M. flagleri Etherington (1931, p. 85, pl. 10, figs. 3, 4) in
having anteriorly, rather than centrally, located
beaks. A specimen of M. flagleri is illustrated (pl. 8, fig.
3) for comparison. A widening of the dorsal margin just
posterior to the beaks indicates that this bivalve had
an external ligament.

Macoma n. sp. Moore (1963) [pl. 8, fig. 4]. An orbicu-
lar specimen that is almost as high as it is long appears
to be the same as Moore’s (1963, p. 81, pl. 29, figs. 10,
11) Macoma n. sp. from near Newport, Oreg. This
species was described as “thin shelled, high in propor-
tion to length, and perhaps almost circular in outline”
(Moore, 1963, p. 81). Although recorded from the As-
toria Formation (Moore, 1963), later mapping has
shown that the seacliff localities 2—3 miles south of
Newport are in the upper part of the Nye Mudstone
(Snavely and others, 1969b, 1976). Data considered

 

33

elsewhere in this report indicate a provincial early
Miocene age for the Nye Mudstone.

VENERIDAE

Dosim'a whitneyi (Gabb, 1866 [pl. 8, figs. 9, 10]. Small,
orbicular specimens of Dosinia from localities M4414,
M4683, M4684, NP160, and NP161 are identical with
material from the Astoria Formation of Oregon iden-
tified as D. whitneyi (Gabb) by Moore (1963, p. 73, pl.
24, figs. 1—10). These specimens are sculptured by fine
concentric ribs and are of variable outline owing to
deformation. The genus is of very rare occurrence in
the Miocene of Oregon where it is known definitely
only from dredgings of middle Miocene age at Coos Bay
(Moore, 1963, p. 73). It also occurs in middle Miocene
strata in southwestern Washington (Etherington,
1931; Addicott in Wolfe and McKee, 1972, table 13)
where it is also rare. The extremely small size of these
specimens suggests that they may represent the north-
ernmost limits of distribution of this warm-water
genus during the early Miocene. Middle Miocene
specimens from southwestern Washington
(Etherington, 1931) and western Oregon (Moore, 1963)
are of much smaller size than those from Oregon. The
genus has been recorded from middle Miocene strata as
far north as Kodiak Island, Alaska (lat 58° N.), but
that occurrence may have been related to a western
North Pacific lineage (Addicott, 1969).

Katherinella angustifrons (Conrad, 1849) [pl. 8, figs. 7,
8, 11—18]. Specimens from the Clallam are extremely
variable in outline and in thickness. Nevertheless they
can be separated into two forms. One has inflated
valves that tend to be of quadrate shape; the other is
only weakly inflated, tends to attain a larger adult
size, is relatively thin shelled, and is usually, but not
always, more orbicular in outline. Some of the thin
orbicular forms attain a relatively large size (pl. 8, fig.
18). The inflated form (pl. 8, figs. 15, 17) occurs in col-
lections from locs. M4051, M4413, M4677, M4683, and
NP163; the thin form (pl. 8, figs. 8, 12, 14, 16, 18) in
M4049, M4050, M4414, M4684, and M5878. The in-
flated form is similar to the type and to specimens from
the Nye Mudstone and the Astoria Formation of the
northwest Oregon coast (Moore, 1963, pl. 24, figs.
11—14, pl. 25, figs. 1—3, 5—15, pl. 26, figs. 4—6, 8). Speci-
mens from localities NP89, NP161, and NP163 are not
differentiated. Katherinella arnoldi ethringtoni (Teg—
land, 1929, p. 283, pl. 23, figs. 12—14), described from
the Clallam Formation and also recorded from the
upper member of the Twin River Formation (Durham,
1944, p. 149), is a synonym of this species.

Securella ensifera (Dall, 1909) [p]. 9, figs. 1—3, 5, 6, 9,
10, 13]. This species is one of the most abundant
bivalves in the Clallam, however, most of the speci-

34

mens are devoid of shell material thereby making
specific identification difficult. The external concentric
sculpture has, nevertheless, been partially preserved
on many of the internal molds. On a few specimens the
sculpture is so well preserved that the fine radial
sculpture underlying the concentric ribbing is exposed.
The original surface sculpture of S. ensifera consisted
of bladelike concentric ridges gently inclined toward
the beaks. Almost all the species, however, have
undergone abrasion or decortication that has exposed a
layer characterized by fine radial ribbing. This species
has been treated systematically by Moore (1963, p.
75—7 6). Specimens described as Venus clallamensis and
V. olympidea by Reagan (1909, p. 182—183, pl. 1, figs.
12 and 13) are synonyms of this species. These are
refigured in this report (pl. 9, figs. 3, l3). Securella, a
genus that became extinct during the provincial
Pliocene, is differentiated from the similar warm-
water genus Chione by its deeply sunken ligament and
V-shaped pallial sinus (Parker, 1949). A specimen
from the basal part of the Clallam identified as S. alas-
kensis (Clark, 1932, p. 815, pl. 18, figs. 2, 3) by Parker
(1949, p. 588) and Chione sp. (Durham, 1944, p. 146)
presumably belongs to this species. Clark’s (1932)
species from the middle Miocene part of the Yakataga
Formation, Alaska [not Poul Creek Formation as
stated by Parker (1949)—see Kanno (1971, p. 87)], may
be a synonym of this species.

HIATELLIDAE

Panopea ramonensis (Clark, 1925) [pl. 9, fig. 15]. This
species has consistently longer valves in proportion to
the height than does P. abrupta, which, also occurs in
the Clallam Formation. The beaks on this species vary
from medial to a position anterior to the midline of the
valves (Addicott, 1973, p. 37—38). The elongate form of
Panopea ramonensis was previously recorded and fig-
ured from the Clallam by Weaver (1942, p. 264, pl. 59,
fig. 11). That record was used by Hickman (1969, p. 60)
and Addicott (1973) in defining a middle Oligocene to
middle Miocene range for this species. This range must
be revised to middle Oligocene to early Miocene in
keeping with the revised provincial age of the Clallam
(Addicott, 1975).

Panopea abrupta (Conrad, 1849) [pl. 9, figs. 7, 8, 16].
This Panopea has more quadrate valves and occurs
more commonly in the Clallam Formation than P.
ramonensis. Panopea abrupta occurs in Miocene to
Holocene formations along the Pacific coast and was
recently recorded from the middle Oligocene of Oregon
(Hickman, 1969, p. 65). Kanno’s (1971, p. 93—94, pl. 11,
fig. 3) Panopea n. sp.? from a locality in the upper part
of the Poul Creek Formation, Gulf of Alaska, is very

 

MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

similar to P. abrupta, differing principally in having a
strongly sloping anterior dorsal margin.

THRACIIDAE

Thracia trapezoides Conrad (1849) [pl. 9, figs. 4, 12].
This late Oligocene to Holocene species, originally de-
scribed from the middle Miocene part of the Astoria
Formation of Oregon, is fairly abundant in the Clallam
Formation. It differs from the late Oligocene to early
Miocene species T. schencki Tegland (1933, p. 112—113,
pl. 6, figs. 6—11) and the Oligocene species T. condoni
Dall (1909, p. 135—136, pl. 19, fig. 5) in having straight
or slightly concave anterior and posterior segments
along the ventral margin creating a lobate ventral
margin. The ventral margin tends, therefore, to be
more convex than in theother species. A further differ-
ence is the generally larger , size of the Oligocene
species (Moore, 1963; Hickman, 1969). On most species
of T. trapezoides, the umbonal ridge setting off the
near-vertical posterior segment of the valve is much
sharper than on older species. The valves of both T.
schencki and T. condoni also tend to be longer in pro-
portion to their height than those of T. trapezoides. The
lowest stratigraphic occurrence of this species is in the
Echinophoria rex zone of northwestern Washington
(Durham, 1944).

Thracia cf. T. schencki Tegland (1933) [pl. 9, figs. 11,
14]. Small elongate specimens from locality M4051
near Slip Point seem to represent this species. Identifi-
cation is doubtful because of limited material and poor
preservation of the specimens. Thracia schencki Teg-
land has a much less convex dorsal margin and has
more elongate valves than T. trapezoides. It also lacks
the broad sinus between the posterior umbonal ridge
and the midline of the valves that is characteristic of T.
trapezoides.

CEPHALOPODS
HERCOGLOSSIDAE

Aturia angustata (Conrad, 1849). This species is
doubtfully identified from a locality about 65 m above
the base of the Clallam Formation (USGS loc. M5878).
There is an undoubted record from the basal part of the
Clallam Formation on the east flank of the anticline
near Slip Point (Arnold and Hannibal, 1913, p. 588;
Miller, 1947, p. 87). Aturia angustata is definitely iden-
tified from near the top of the underlying upper
member of the Twin River Formation close to the
mouth of Pysht River (Schenck, 1931) and is of more
common occurrence in collections from the type section
of the lower Miocene Echinophoria apta zone near the
mouths of the Twin Rivers several kilometres farther
east (Arnold and Hannibal, 1913; Durham, 1944).

FOSSIL LOCALITIES

Occurrences of Aturia angustata in the California
Miocene are very rare. The two records listed by
Schenck (1931) are from strata northeast of Bakers-
field, Calif., that are referable to the upper part of the
“Vaqueros” Stage of Addicott (1972). The lowest of
these records is from near the base of the Temblor
Formation according to Schenck (1931). Records from
Oregon (Moore, 1963) seem to be from the lower
Miocene Nye Mudstone of the Newport Embayment or
from the lower Miocene part of the Astoria Formation
in more northern Miocene embayments. This taxon
has not been recorded from the Astoria Formation in
southwestern Washington. The fragmentary strati-
graphic evidence points toward a pre-middle Miocene
range for this species. Tentatively, it is considered to
have become extinct during the later part of the pro-
vincial early Miocene.

SCAPHOPODS
DENTALIIDAE

Dentalium pseudonyma Pilsbry and Sharp (1898) [pl.
4, figs. 4, 8]. This radially ribbed species is of less com-
mon occurrence in the Clallam than the larger
smooth-shelled D. schencki Moore. Further differences
from D. schencki are the relatively thinner shell and
straighter, less tapered form.

Dentalium schencki Moore (1963) [pl 5, fig. 11]. This
relatively large smooth-shelled species, strongly ta-
pered, is fairly abundant in the Clallam Formation.
Both Dentalium schencki Moore and D. pseudonyma
also occur in the middle Miocene part of the Astoria
Formation of the Newport Embayment, Oreg. (Moore,
1963).

FOSSIL LOCALITIES IN THE
CLALLAM FORMATION,
CLALLAM COUNTY,
NORTHWESTERN WASHINGTON

US. Geological Survey localities, Menlo Park register

M4049. Sea cliff and intertidal zone exposures near center of El/z of
sec. 32, T. 32 N., R. 11 W., 2,300 ft north, 1,300 ft west of
SE cor. sec. 32, T. 32 N., R. 11 W., Pysht 15-minute
quadrangle. From three l-m—thick beds in an interval
between 191 and 207 In above the base of the formation.
Collected by W. O. Addicott, 1968, and Addicott and J.
W. Miller, 1974. Same as UCMP A3962.

Sea cliff and intertidal zone exposures 1,800 ft north, 700 ft
west of SE cor. sec. 32, T. 32 N., R. 11 W., Pysht 15-
minute quadrangle. From interval 52—59 m above the
base of the formation. Collected by W. O. Addicott, 1968.
Same as UCMP A3693.

Macoma arctata beds about 10 m thick exposed in sea cliff
almost 1 km east of Slip Point, 4,550 ft north, 700 ft west
of SE cor. sec. 21, T. 32 N., R. 12 W., Pysht 71/2-minute
quadrangle. Collected by W. O. Addicott, 1968.

M4050.

M4051.

 

M4413.

M4414.

M4675.

M4677.

M4678.

M4679.

M4680.

M4681.
M4683.

M4684.

M5878.
M5879.
M5885.

M5886.

M6029.

M6373.

35

Intertidal exposure of sandstone with scattered Vertipecten
and Epitonium about 1V2 km east of Slip Point, 3,000 ft
north, 2,400 ft east of SW cor. sec. 22, T. 32 N., R. 12 W.,
Pysht 15—minute quadrangle. Collected by W. 0. Ad-
dicott, 1970, and Addicott and J. W. Miller, 1974.

Talus from seacliff exposure nearly 3 km east of Slip Point,
600 ft north, 2,100 ft east of SW cor. sec. 23, T. 32 N., R.
12 W., Pysht 15-minute quadrangle. From an interval
approximately 40—110 m above the base of the forma-
tion. Collected by W. O. Addicott, 1970.

Seacliff and intertidal zone exposures about two-thirds of a
kilometre west of Pillar Point, 100 ft north, 500 ft east of
NW cor. sec. 3, T. 31 N., R. 11 W., Pysht 15-minute
quadrangle. Collected by W. O. Addicott and J. E. Pearl,
1971.

Intertidal zone exposures at north end of gravel beach at
Slip Point, 4,900 ft north, 200 ft west of SE cor. Clallam
Bay 15-minute quadrangle. Approximately 180 m above
the base of the formation. Collected by W. O. Addicott,
1971.

Natural exposure on south side of logging road at top of
steep sea cliff, 600 ft north, 800 ft west of SE cor. sec. 25,
T. 32 N., R. 12 W., Pysht 15-minute quadrangle. Eleva-
tion 880 ft. Near the top of the formation. Collected by
W. O. Addicott, 1971, and Addicott and J. W. Miller,
1974.

Intertidal zone exposure about 4 km west of Pillar Point,
4,400 ft north, 300 ft east of SW cor. sec. 32, T. 32 N., R.
11 W., Pysht 15-minute quadrangle. Collected by W. O.
Addicott, 1971.

Intertidal zone exposure about 150 In southeast of M4679,
4,100 ft north, 400 ft east of SW cor. sec. 32, T. 32 N., R.
11 W., Pysht 15—minute quadrangle. Collected by W. O.
Addicott, 1971.

Same as M4414. Collected by W. O. Addicott, 1971.

Intertidal zone exposure about 11/2 k west of Pillar Point,
500 ft north, 3,700 ft east of SW cor. sec. 33, T. 32 N., R.
11 W., Pysht 15-minute quadrangle. Collected by W. O.
Addicott and J. E. Pearl, 1971.

Intertidal zone exposure approximately two-thirds of a
kilometre west of Pillar Point, 250 ft north, 400 ft east of
NW cor. sec. 3, T. 31 N., R. 11 W., Pysht 15—minute
quadrangle. Collected by W. O. Addicott and J. E. Pearl,
1971.

Same as M4049. Collected by W. O. Addicott, 1973.

Same as M4050. Collected by W. O. Addicott, 1973.

Intertidal zone exposure at base of sandy beach approxi-
mately 3 k west of Pillar Point, 2,800 ft north, 3,300 ft
east of SW cor. sec. 32, T. 32 N., R. 11 W., Pysht 15-
minute quadrangle. Collected by W. O. Addicott and J.
E. Pearl, 1973.

Prominent point about one-half a kilometre east of Slip
Point, 5,100 ft north, 1,400 ft west of SE cor. sec. 21, T. 32
N., R. 12 W., Pysht 15-minute quadrangle. Collected by
W. O. Addicott, 1973.

Intertidal exposure of massive, Vertipecten-bearing
sandstone at base of gravel beach at Slip Point Light-
house compound, 300 ft west, 4,250 ft north of SE cor. of
Clallam Bay 15-minute quadrangle. Approximately 130
In above the base of the formation. Collected by W. O.
Addicott, 1973.

Intertidal zone exposure of l-m-thick fossil bed 27 m N. 26°
W. of M4049 and 12 m stratigraphically above M4049, in
Nl/ZNl/ZSEIA sec. 32, T. 32 N., R. 12 W., Pysht 15-minute
quadrangle. Approximately 230 m above the base of the

36 MOLLUSCAN PALEONTOLOGY, LOWER MIOCENE CLALLAM FORMATION, NORTHWESTERN WASHINGTON

formation. Collected by W. 0. Addicott and J. W. Miller,
1974.

Large blocks of silty sandstone at base of cliff about 100 m
west of giant talus pile 550 ft north, 1,850 ft east of SW
cor. sec. 23, T. 32 N., R. 12 W., Pysht 15-minute quad-
rangle. Lowest 20—40 m of the formation. Collected by W.
O. Addicott and J. W. Miller, 1974.

M6375.

Stanford University localities

[These descriptions are from the Stanford University locality register. Published
descriptions in Arnold and Hannibal (1913, p. 589) are different in some respects]

NP89. Oligocene-Miocene, Monterey basal sandstone, seacliffs
eastward from Slip Point for half a mile, Clallam Bay,
Wash. Collected by A. B. Reagan and Harold Hannibal,
1911, 1912. USGS localities M4051 and M5886 are from
the same area.

Monterey sandstone, seacliffs at Pillar Point, straits east of
Clallam Bay, Wash. Collected by Harold Hannibal,
1912. USGS localities M4675, M4683, and M4684 are
from the same area.

Monterey shale and sandstone, seacliffs 1‘/2 miles west of
Pillar Point, Clallam Bay, Wash. Collected by Harold
Hannibal, 1912. USGS localities M4049 and M4050 are
from the same area; the assemblage from M4049 most
closely resembles that of NP161.

Monterey carbonaceous sandstone, seacliffs at coal mine,
straits east of Clallam Bay, Wash. Collected by Harold
Hannibal, 1912. Probably stratigraphically higher than
M4678 which is from the same area.

Oligocene-Miocene, Monterey shaly sandstone east of Clal—
lam Bay, Wash. Collected by Harold Hannibal, 1912.
Probably same locality as M4681.

NP160.

NP161.

NP162.
NP163.

Washington University (Seattle) localities

UW270. Cliff, south shore of Strait of Juan de Fuca, Clallam
County, sec. 23, T. 31 N., R. 12 W. (Weaver, 1942).

Very shaly sandstone in cliff, beach section 11,000 ft
southeast of Slip Point and 13,000 ft due east of the town
ofClallam Bay, Clallam County, NEIASE‘A sec. 22, T. 32

N., R. 12 W. (Weaver, 1942).

UW490.

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Page
A
abrupta, Panope __________________________________ 4
Panopea ,,,,,,,,,,,,,,,,,,,, 4, 6, 14, 18, 34, pl. 9
Acila __________________________________________ 27
conrudi ______ 4, 5, 14, 27, pl. 3
gettysburgensis ___________________ 17
(Acila) castrensis, Nucula _ _________ 4
conradi, N ucula _____________________________ 4
Acknowledgments ________________________________ 3
acutilineata, Lucinoma ______ 4, 5, 14, 18, 19, 30, pl. 5
acutilineatus, Phacoides _________________________ 4
aequisulcatum, Semicassis ___________________
Age _____________________________________
Alaska ....
Alaska Peninsula, Miocene assemblages ____________ 2
alaskensis, Securella ____________________________ 34
albaria, Macoma __________________ 6, 14, 15, 32, pl. 7
Spisula ________________ 4, 5, 14, 15, 31, pls. 6, 7
gondspeedi, Spisula ________ 5, 10, 14,31, pls. 6, 7
alta, Metis _______________________________________ 4
Amauropsis oregonensis ,,,,,,,, A. 4
Anadara ________ -_ we 19, 28
devincta , _ 5, 12, 14,28, pl. 5
lakei , 14, 15,28, pl. 5
5.5 ,,,,, __ 20
submontereyamz ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 28
Ancistrolepis clarki ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 23
clarki teglandae ___________________________ 23
rearensis __________ 5, 10, 14, 15, 16, 17,23, pl. 3
anglonana, Molapophorus ________________________ 24
angustata, Aturia __________________________ 6, 14, 34
angustifrons, Katherinella ,, 4, 6, 14, 15, 33, pl. 8
Venus, (Chione) . _.__ 4
annulata, Lucinoma , _ 18, 19
Antigona olympidea ______________________________ 4
antiselli, Thesbia ________________________________ 26
Xenuroturris ,,,,,,,,,,,,,,,,,, 5, 15,26, pls. 2, 3
apta, Echinophoria ______________ _.__ ___ 23
Liracassis _______________________________ l7
Archarax ________________________________________ 18
dalli _______ 5, 10, 11, 13, 14, 16,28, pl. 3
uentricosa .. _____ __ 28
willapaensis _ 28
Arcidae ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 28
arctatu, Macoma ,,,,,,,,,,,,,,,, 3, 4, 6, 14,32, pl. 7
Tellina ____________________________________ 3, 4
juana, Tellina ______________________ 4, 32, pl. 7
Armentrout, J. M., cited ________________________ 16
Arnold, Ralph, cited ,,,,,,,,,,,,,,,,,,,,,,,,,, 6, 7
arnoldi, Macoma , 32, pl. 7

   
 

ethringtoni, K atherinella _ _ _

astori, Macoma ,,,,,,,,,,,,,,,, 6, 10, 14, 19, 32, pl. 7

Astoria, Oreg ________________________________ 15, 18

Astoria Formation ,,,,,,,,,,,,,,,,,,,,,,,,,, 26, 33
age ________________________________________ 16
benthonic foraminifera ,,,,,,,,,,,,,,,,,,,, 16
contact ___________________

  
  
 

fauna, Newportian _
middle Miocene ,,,,,
molluscan fauna ,,,,,,

Miocene fauna ________________________ W 3, 16
Newport Embayment, Oreg __________________ 28
Oregon ________________ 3, 10, 12, 16, 17, 20, 21,
25, 26, 27, 28, 29, 31, 33, 34, 35

southwestern Washington ,,,,,,,,,,,,,, 3, 10, 17,
23, 24, 26, 27,28, 29, 31, 35

type area __________________________________ 18

  
 
 

 

INDEX

[Italic page numbers indicate major references]

 

   
  
 
 
 

 

 

  
    

Aturia ,,,,,,,,,,
angustata ____________________________ 6, 14,34
B
Baja California, Mexico _________________________ 20
Bakersfield, Calif _____________________ __- 35
Barker’s Ranch fauna ,,,,,,,,,,,,,,, 1.- 13
Bathymetry ______ _t, 18
Biostratigraphy _
birchi, Cancellaria, ______ 5, 15,25, pl. 2
bisecta, Canchocele ______________________________ 30
Blakeley Formation, Washington ______________ 25, 30
Blakeley Stage ,,,,,,,,,,,,,,,,,, 6, 13, 16, 18, 29, 31
British Columbia ___________
brota, Mocoma _________________________________ 19
Bruclarkia ______________________________________ 23
aregonensis _ _ 4, 5, 14,23, pl. 2
yaquinana ,,,,, . ,,,,,,,,,, 5, 14, 15, 23, pl, 2

Buccinum clallamensis ,, -1
bulbasus, Teredo ,,,,,,,,,,

 

  
  

C
California, Coast Ranges ____________________ 12, 18
formaminiferal correlation __________________ 16
middle Miocene strata ____________________ 12, 20
Temblor Stage __________________________________ 12
Vaqueros Stage _________________________ 12, 13
calkinsi, Nuculana _______________ 5, 14, 15, 27, pl. 3
Calyptraea sp _______________________________ 4
Calyptraeidae ..... 21
Canada, western, provincial molluscan stages 1 4

 

Cancellaria ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

 
 

birchi ,,,,,,,,,,,,,, fl 5, 15,25, pl. 2
oregonensis ,1 5, 15,25, 26, pl. 2
siletzensis _ ______________ 5, 11, 15, 25, p]. 2
simplex _____________________ 5, 12, 15,25, pl. 2
wynoocheensis ,,,,,,,,,,,,,,,, 5, 12, 15,26, pl. 2
(Euclid) _________________________________ 20
Cancellariidae ,,,,,,,,,,,,,,,,,,,,,,,,,

 
  
 
 
 
  
  

Cape Yakataga, Alaska _________________
Cardiidae ______________
Carditidae ______________
Carnivore, marine
Cassididae ,,,,,,,,,,,,,,,,,,
caster, Cyclacardia _____________________________ 30
castrensis, Nucula (Acila)
catilliformis, Spisula ,,,,,,,,,,,,,,,,
centiquadrata, Semicassis
Cephalopods ,,,,,,,,,,
Cetacean bones _______
chehalisensis, Nuculana
Chione ,,,,,,,,,,,,,,,,,,,,,,,,,,,

securis

sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,
(Chione) angustifrons, Venus ,,,,,,,,,,,,,,, W 4

clallamensis, Venus __________________

olympidea, Venus W"
(Chlamys) fucanus. Pecten ,,

 

 

 

  
  
  

 

wattsi morani, Pecten ,, ,,,,,,,,,,,,,,, 4
Clallam Bay __________________________ 1, 3, 6, 21, 30
Clallam coal mine
Clallam County, Washington __________________ 35

Washington, fossil localities _________________ 35
Clallam fauna, late early Miocene _ n, 20

 
 
 

Clallam Formation __________

 

Clallam Formation—Continued
benthonic foraminifera __
contact ______________
correlation ______
depositional cycle
depositional environment _____

 
 
 
 

 

exposures _________________________________ 1, 8
fauna _____________________ 3, 4, 5, 6, 16, 17,20
Pillarian ________________________________ 17

faunal assemblages A. 10, 11, 12, 18, 19

 
    
 
 
 

  
 

fauna] hiatus ________ __, 9, 10, 16
fossil localities 8, 9, 11, 35
fossils“

lithology __ _____________________ 1, 7
living Species ________________________________ 18
marine carnivore ____________________________ 4
marine mollusks __________ 1, 2, 3, 10, 15, 17, 18
microfaunal boundary _______________________ 16
Miocene assemblages ,,,,,,, 2, 7, 12, 19
Miocene boundary ,1 _, 2
molluscan fauna __,, _ 20
nomenclatorial history ______________________ 6, 7
Oligocene-Miocene boundary _________________ 2

 
 
 
 
 
  
  
 

provincial chronostratigraphy ,,,,,,,,,,,,
restricted species _____
stratigraphy
thickness ___________
type locality

   
 
 
  

 

 
 
   

type section ______________________ , 18
unconformity _ _ __ _ 16
Washington ______ _ __________ 21
clallamense, Epitonium V 5, 14, 16, 17,21, pl. 1
clallamensis, Buccinum __________________________ 4
Pisania ______________________________________ 4
Tellina ______________________________ 4, 32, pl. 7
Trophosycon ,,,,,,,,,,,,,, 5, 14, 15, 23, pls. 1, 2
Venus 1.- 34, pl. 9
(Chiane) ____________________ 4

clarki, Ancistrolepis- ..... 23
Natica ___ _____ 5, 14,22, pl. 1
Priscofusus _________________ 24
teglandae, Ancistrolepis _____________________ 23
Clinocardium W, _____________________________ 30
nuttalli _______________ 5, 11, 14, 19, 30, pls. 5, 6
sookensis ___________________________________ 31
yokatagense __________________________ 31

A. 30, pls. 5, 6

Coast Ranges, California . 12, 18, 23

columbiana, Luciuoma ,
Conchocele bisecta .....

  
 
  
 

disjuncta _________________ 5, 11, 14, 18,30, pl. 6
condonana, Megasurcula ______________________ 27
condoni, Thracia ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 34
conradi, Acila ,,,,,,,,,,,,,,,,,,,,,, 4, 5, 14,27, pl. 3

N ucula (Acila) ____________________ 4

Solen _______________ 6, 14,31, pl. 6
Coos Bay____ _______ 33
Correlation ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 12

foraminiferal ________________________ 12, 13, 16

molluscan ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 12, 16

corrugata, M usashia , ,,
Crenella porterensis ,,,,,
Crepidula ____________________________________ 21, 22

 

 
   

praerupta _ 5, 14, 21, 22, pls, 1, 2
princeps A, e, 5, 10, 14,21, pl. 1
rostralis e_ 5, 14,22, pl. 2
sookensis ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 22
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5,22, pl. 1

41

42

  

 

 

 

 

Crescent Formation ,,,,,,,,,,,,,,,,,,
Cuyama Valley area, California _____ _ 23
Cyclinella sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
Cyclocardia Castor ,,,,,,,,,,,,,,,,,,,,,,,,, 30
subtenta ,,,,,,,,,,,,,,,,, 5, 14, 15,30, pls. 5, 6
yakatagensis ,,,,,,,
D
dalli, Archarax 5, 10, 11, 13, 14, 16, 28, pl. 3
Dentaliidae ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 35
Dentalium pseudonyma ,,,,,,,,,,,, 4, 5, 15,35, pl. 4
schencki ,,,,,,,,,,,,,,,,,,,,,,,, 5, 15,35, pl. 5
substriatum ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
devincta, Anadara ,,,,,,,,,,,,,,,, 5, 12, 14,28, pl. 5
Dibblee, T. W., Jr., cited ,,,,,,,,,,,,,,,,,,,,,,, 27
disjuncta, Conchocele _________ 5, 11, 14, 18, 30, pl. 6
Dosinia ,,__ ___________________________ 19, 20, 33
whitneyi ,,,,,,,,,,,,,,,,,,,,,,,, 6, 14, 33, pl. 8
E
East Clallarn ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 3
East Twin River ________________________________ 30
Echinophoria apta ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 23
apta zone ____________________ 6, 7, 18, 23, 32, 34
rest zone ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 25, 34
elmana, Nuculana ,,,,,,,,,,,,,,,,,,,, 5, 14, 27, pl. 3
emacerata, Tellina ______________ 4, 6, 14, 15,31, pl. 7
ensifera, Securella ,,,,,,,,,,,,,, 4, 6, 14, 15, 33, pl. 9
Eocene-Miocene depositional cycle ________________ 1
eparchis, Nuculana ______________________________ 27
Epitoniidae ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 21
Epitonium clallamense ,,,,,,,, 5, 14, 16, 17,21, pl. 1
equilateralis, Spisula ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 31

ethringtoni, Katherinella arnoldi ,
Euclia ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

 

 

(Euclid), Cancellaria ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 20
F

F elaniella ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 30
parilis ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 14, 30
Sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5, 30, pl. 5

Ficidae ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 23

Ficus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 19, 20
modesta ,,,,,,,,,,,,,,,,,,,,,,,,,, 5, 14, 23, pl. 1

filasa, Trochita ,,,,,,,,,,,,,,,,,,,,,,

 

flagleri, Macoma ,,
Foraminifera, benthonic“, 2, 4, 12, 13, 16, 18, 20, 27

 

 

 
   
 
 
 
 

 

Jewett Sand ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 13
Luisian ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27
Relizian ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27
Saucesian ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 13, 16, 27
Fossil, bathymetric index ,,,,,,,,,,,,,,,,,,,,,,, 19
Fossil localities, Clallam County, Washington J" 35
Clallam Formation ,,,,,,,,,,,,,,,,,,,,,,,,,, 35
Stanford University ,,,,,,,,,,,,,,,,,,,,,,,, 36
stratigraphic sequence J, ,,,,,,,, 8, 9
U.S.G.S., Menlo Park register ________ 8, 9, 11, 35
Washington University (Seattle) ,,,,,,,,,,,,,,, 36
Fossil species, Oregon ____________________________ 10
Washington ,,,,,,,,,,,,,,,,,,,,,,,,,, , 10
Fossils, Astoria, Oreg ,,,,,,,,,,,,,,,,,,,,,, , 15
index species ,,,,,,,,,,,,,,,,,,,,, M, 13
preservation ,,,,,,,,,,,,,,,,,,,,,,, W 6, 16
restricted species ,,,,,,,,,,,,,,,, , 10, 11
zonal index species ....... "M 10
Freeman Silt ,,,,,,,,,,,,,,,,, _ J 27
fucanus, Pecten (Chlamys) ,,,,,,,,,,,,,
Vertipecten ,,,,,,,,,,,,,, 4, 5, 10, 13, 14, 15, 16,
17, 27,29, pl. 4
Fusinidae ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 24
Fusinus hannibali ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 24
G
Gastropod fauna ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 3
Gastropods ,,,,,,,,,,,,,,,, 4, 5, 6, 14, 15, 16, 20,21
generosa, Panopea ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4

 

 

 

 

  
 

INDEX
Page
geniculus, Priscofusus __________ 5, 11, 15, 16, 24, pl. 2
gettysburgensis, Acila __________
gibbosus, Saxidomus ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
gibbsana, Mactra ,,,,,,,,,,,,,,,,,,,,,,,, 4, 31, pl. 7
Glycymerididae _______________________ . 28
Glycymeris ______ _. 28
sp ,,,,,,,,,,,,,,,,,,,,, 4, 5, 28, pl. 5

goodspeedi, Spisula albaria .J- 5, 10, 14, 31, pls. 6, 7

 

   

 

 
 
 
  
  
  
  

Gower, H. D., cited ,,,,,,,,,,,,,,,,,,,,,,, _. 9, 24
goweri, Priscofusus ____________ 4, 15, 20,24, 25, pl. 2
graciosana, Ophiodermella ,,,,,,,,,,,,,,,, 26
Grays Harbor basin, Washington ,,,,,,,,,,,,, 27
Grays River quadrangle, southwestern
Washington ,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 18, 26
Gulf of Alaska ,,,,,,,,,,,,,,,,,,,, _ 25, 30, 31, 32
Miocene fauna ,,,,,,,,,,,,,,,,,,,,,,,, 2, 17, 21
H
Hannibal, Harold, cited .......................... 20
hannibali, Fusinus ,,,,,,, ,, 24
Lucinoma ,,,,,,,,,, 1, 30
Priscofusus ,,,,,,,,,,,,,,,,,,,,,,, 24, 25
Spisula ___________ 5, 10, 13, 14, 16,31, pl. 6
Hercoglossidae ...... , 34
Hiatellidae ,,,,,,,,,,,, __ 34

Hoh Formation ,_ _ . .
Hoh rock assemblage
Hokkaido, Japan _
Hoko River _______

 

iani, Semicassis
impressa, Yoldia , _

 

 

 

 

   

 

 

 
 

  

 

 
 

indurota, Musashia ,,,,,,,,,,,,,, 5, 11, 15,25, pl. 3

inornata, Trochita ________________________________ 4

Introduction ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 1, 6

J

jamesae, Neuerita ,,,,,,,,,,,,,,,,,,,, 5, 14, 22, pl. 1

Japan ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 18, 23

Jewett Sand ,,,,,,,,,,,,,,,,,,,,,,,,,, 13, 21, 26, 30

juana, Tellina arctata ,,,,,,,,,,,,,,,,,,,, 4, 32, pl. 7

Juanian Stage ________________________ 6, 16, 17, 18

K

Kamchatka ,,,,,,,

Russia ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 32

Katherinella angustifrons ,,,,,,,, 4, 6, 14, 15,33, pl. 8
arnoldi ethringtoni ,,,,,,,,,,,,,,,,,,,,,,,,,, 33

Keasey Formation ,,,,,,,,,,,,

kernianum, Trophosycon ,,,,,,

Kodiak Island, Alaska

Kuluven Suite ,,,,,,,,,,,,,,,,,,,,,,

L

lakei, Anadara ,,,,,,,,,,,,,,,, 5, 11, 14, 15,28, pl. 5

Last Creek

Lincoln Creek Formation ,,,,,,,,,,,,,,,,,,,

Lincoln Stage

lipara, Macoma ,,,,,,,,,,,,,,,,,,

Liracassis apta ,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Lucinidae ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Lucinoma ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
acutilineata ,,,,,,,,,,,, 4, 5, 14, 18, 19,30, pl. 5
annulata ,,,,,,,,,,,,,,,,
columbiana ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 30
hannibali ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 30

(Lunatia) olympidii, Polynices

Lyre Formation ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 7

M
McCormick, Lavon, cited ,,,,,,,,,,,,,,,,,,,,,,,, 20
Macoma

 

 

 

 

 

 

 

  

Page

Momma—Continued
albaria ______________________ 6, 14, 15, 32, pl. 7
arctata ______________________ 3, 4,6, 14, 32, pl. 7
amoldi ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 32, pl. 7
astori ,, 6, 10, 14, 19,32, pl. 7
19
flagleri ________________________________ 33, pl. 8
lipara ______________________________________ 33
nasuta __________________________________ 32, 33
secta _____________ 6, 12, 14, 15, 19, 20, 33, pl. 8
sookensis ____________________ 6, 14, 33, pls. 7, 8
twinensis ,,,,,, 6, 10, 11, 13, 14, 16, 32, pls. 6, 7
n. sp _________________ 6, 14, 15, 16, 20,33, pl. 8
Mactra gibbsana ______________________ 4, 31, pl. 7
Mactridae _______________________________ A, 31
Mactrids _____ W., 19
Marcia oregonensis ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
Matlockian Stage __________________ 6, 13, 16, 18, 29
matthewi, Molapophorus ,,,,,,,,,,,,, ,___ 16, 24
Megasurcula ____________________________________ 27
condomzna __________________________________ 27
wynoocheensis ________________ 5, 15, 19,27, pl. 3

 
 
 
  

middendorffi, Mytilus 1,,
Miocene, index species ._
Miocene assemblages A

 

 

Miocene boundary ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2
mollusks ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2
Miocene fauna, Astoria Formation ________________ 3
Gulf of Alaska ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 3
modesta, Ficus ______________________ 5, 14,23, pl. 1
Modiolus ________________________________________ 28
restorationensis ,,,,,,,, 5, 11, 14, 15, 20,28, pl. 5
n. sp ______________ 20, 28, pl. 5
Molluscan fauna fl- 3, 4, 7, 9, 10, 12, 18,20
Molluscan paleontology __________________________ 20
Molluscan province, late early Miocene ,,,,,,,,,, 2, 3
Mollusks, depth ranges ,,,,,,,,,,,,,,,,,,,,,,,,,, 18
index species ________________________________ 13
living genera ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 19
stratigraphic distribution .......... 10, 11, 13, 15

Molopophorus _ _ _
anglonana _ - _

 

matthewz ________________________________ 16, 24

newcumbei ,,,,,,,,,,,, 5, 14, 15, 16, 20,24, pl. 2

n. sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 20, 24, pl. 2
Monterey Formation ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 6
Montesano Formation, Weaver ,,,,,,,,,,,,,,,,,, 31
Moore, E. J., cited ,,,,,,,,,,,,,,,,,,,, 20, 21, 25, 27
Moore, R. C., cited ,,,,,,,,,,,,,,,,,,,,

 

morani, Pecten (Chlamys) wattsi ,,,,,,,,,,,,,,,,,, 4
muirensis, Ophiodermellu ,.
Muricidae ________________

 
 
 
 

 

 

 

   
  

 

 

M usashia
corrugata
indurata ______________________ 5, 11, 15, 25, pl. 3
weaveri ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 17
Mytilidae ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 28
Mytilids ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 6
Mylilus _____________________________________ 3, 19
middendorffi ,,,,,,,,,,,,,,,,,,,,,, .11, 13, 29
ochotensis ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 28, 29
tichanouitchi ,,,,,, 5, 13, 14, 16, 19, 20,28, pl. 5
n. sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 15, 20, 28, pl. 5
N
nasuta, Macoma ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 32, 33
Natica ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, , ______ 19
clarki ,,,,,,,,,,,,,,,,,,,,,,,, -_ 5, 14, 22, pl. 1
vokesi ________________________ __ 5, 14,22, pl. 1
Naticidae ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 22
Neptuneidae ,,,,,,,,,,,,,,,,,,,,,,,, 23
Neverita ________________________ , _- ,. 19
jamesae ,,,,,,, _ 5, 14, 22, pl. 1
(Neverita) saxea, Polynices ,,,,,,,,,,,,,,,,,,,,,,,, 4

newcombei, Molapophorus __ 5, 14, 15, 16, 20,24, pl. 2
Newell, N. D., cited ______________________________ 20

  

   

 

    
 

  
  
  
  
 
  

 

 

 

 

 

 

 

 

 

 

 

Page
Newport, Oregon ____________________________ 24, 33
Newport Embayment, Oreg-- 13, 15, 16, 18, 21, 28, 35
Newportian Stage ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 17
N ucula (Acila) castrensis _______
(Acila) conradi
Nuculana calkinsi ________________ 5, 14, 15,27, pl. 3
chehalisensis __________________ 5, 12, 14,27, pl. 3
elmamz ________________________ 5, 14, 27, pl. 3
eparchis ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27
Nuculanidae ____________________________________ 27
N uculidae ___________________________________ 27
nuttalli, Clinocardium ______ 5, 11, 14, 19, 30, pls. 5, 6
Nye Mudstone _____________ 11, 15, 16, 25, 27, 28, 33
age ______________________ . 16, 17
benthonic foraminifera ______________________ 16
contact ______________________________________ 15
fauna . ________ 16, 18,21, 24
Oregon ,,,,,,,
O
ochotensis, Mytilus __________________________ 28, 29
Oligocene-Miocene boundary, foraminifera ,,,,,,,,,, 2
Olympic Mountains, Wash ______________________ 18
Olympic Peninsula, Washington ____________ 1, 27, 30
olympicensis, Ophiodermella ..-. 4, 5, 15, 20, 26, pl. 3
alympidea, Antigona . _____________ 4
Venus ,,,,,,,,,, 1-. 34, p]. 9
(Chione) ___________
olympidii, Polynices (Lunatia) ________ 4
Ophiodermella __________ 26
graciosana _____ .-- 26
muirensis __________ 26
olympicensis ___________ 4, 5, 15, 20, 26, pl. 3
workensis ____________
n. sp ______________________________
Oregon, middle Miocene strata ,,,,,,,,
molluscan province ..-. ,,,,,,,,,,,,,,,
Nye Mudstone ___________________________ 16
zonal index species __________________________ 10
oregonensis, Amauropsis __________________________ 4
Bruclarkia ,,,,,,,,,,,,,,,,,,,, 4, 5, 14, 23, pl. 2
Cancellaria _________________ 5, 15,25, 26, pl. 2
Marcia _________________________ 4
Tellina ______________________________________ 4
Turritella _______________________ 5, 14,21, pl. 1
(Oudardia) sp., Tellina __________________________ 32
P
Pacific coast __________________________ 19, 21, 23, 32
Pacific Northwest States, provincial
molluscan stages _________________________ 4
Page Mill Basalt ___________________
Paleoclimate ________________________
Paleoecology __________
Panamic molluscan province
Panope abrupta _________________________________ 4
Panopea ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 18, 34
abrupta ,,,,,,,,,,,,,,,,,,,, 4, 6, 14, 18, 34, pl, 9
generosa ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
ramonensis ______________________ 6, 14, 34, pl. 9
n, sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 34
parilis, Felaniella ____________________________ 14, 3O
Patinopecten ____________________________________ 15
propatulus __________________________ 13, 16, 29
(Patinopecten) propatulus, Pecten ,,,,,,,,,,,,,,,,,, 4
patulus, Petunculus ______________________________ 4
Pecten (Chlamys)fucanus ________________________ 4
(Chlamys) wattsi morani ,,,,,,,,,,,,,,,,,,,,,, 4
(Patinopecten) propatulus ______________________ 4
Pectinidae ______________________________________ 29
Pectinids ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 6, 10, 13
Pelecypod fauna ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 3
Pelecypods ,,,,,,,,,,,,,,, 4, 5, 10, 14, 15, 16, 20,27
Petunculus patulus _______________________________ 4
Phacoides acutilineatus ,,,,,,,,,,,,,,,,,,,,,,,,, 4
Phalium _____________________________________ 22
Pillar Point ______ 3, 7,8, 9, 12, 19, 21,24, 25, 27, 28

Pillarian Stage ____________________ 6, 12, 16, 17, 18

 

  
  
 
 
 
  

 

 

INDEX
Page
Pillarian Stage—Continued
type section ____________________ 2, 18
Pisam‘a clallamensis __
Polinices saxea _________
victorianus ________
Palynices (Lunatic) olympidi
(Neverita) saxea _________
Porter Bluffs, Washington---.
porterensis, Crenella ,,,,,,,,,,,,,,,,,,, 29
Salamen ,,,,,,,,,,,,,,,,,,, _ 29, pl. 4
Poul Creek ______________________________________ 17
Poul Creek Formation,
Gulf of Alaska ______________ 21, 23, 30, 31, 32, 34
molluscan assemblages ______________________ 17
praerupta, Crepidula ,,,,,,,,,, 5, 14,21, 22, pls. 1, 2
Previous faunal studies __________________________ 3
princeps, Crepidula ,,,,,,,,,,,,,,,, 5, 10, 14,21, pl. 1
Priscafusus __________________________________ 24, 25
clarki ______________________________________ 24
geniculus ________________ 5, 11, 15, 16,24, pl. 2
goweri ____________________ 4, 15, 20, 24, 25, pl. 2
hannibali _______________________________ 24, 25
slipensis ,,,,,,,,,,,,,,,,, 4, 5, 15, 20, 24, pl. 2
stewarti ____________ 5, 10, 11, 15, 16, 24,25, pl. 2
n. sp _________________________________ 24, 25
propatulus, Patinopecten __________________ 13, 16, 29
Pecten (Patinopecten) __________________________ 4
Provincial chronostratigraphy ____________________ 12
Provincial molluscan stages ______________________ 4
pseudonyma, Dentalium ,,,,,,,,,,,, 4, 5, 15, 35, pl. 4
Pysht River ________________________________ 1, 7, 34

pyshtensis, Semicassis.__. 4, 5, 11, 14, 15, 20,22, pl. 1

 

 

 

Q
quadrata, Venericardia subtenta __________________ 30

R
ramonensis, Panopea ,,,,,,,,,,,,,,,,,, 6, 14, 34, p]. 9
Raymond quadrangle, Washington ,,,,,,,,,,,,,,,, 27
Reagan, A. B., cited ,,,,,,,,,,,,,,,,,,,,,,,,,, 3, 20
reagani, Yoldia ,,,,,,,,,,,,,,,,,,,,,,,,,,,, ..._ 4
rearensis, Ancistrolepis _. 5, 10, 14, 15, 16, 17,23, pl. 3
Rectiplanes ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 26
sp __________________________________ 5, 26, pl. 2
Reed Creek ______________________________________ 7
References cited ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 36
Relizian Stage ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 16
restorationensis, Modiolus .. 5, 11, 14, 15, 20,28, pl. 5
Rexithuerus ____________________________________ 33
rostralis, Crepidula ,,,,,,,,,,,,,,,,,, 5, 14,22, pl. 2

S
San Francisco Bay region, California ______________ 27
San Joaquin basin, Calif ,,,,,,,,,, 13, 23, 25, 26, 29
San Pablo Group ________________________________ 31
Saucesian Stage ______________________________ 4, 16
foraminiferal assemblages ______ .... _..- 27
saxea, Polinices ____________________ _..- .__, 22
Polynices (Neuerita) __________________________ 4
Saxidomus gibbosus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
Scaphopods ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4, 5, 15,35
Schenck, H. G., cited ,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27
schencki, Dentalium ,,,,,,,,,,,,,,,,,, 5, 15,35, pl. 5
Thracia ,,,,,,,,,,,, 6,10,13, 14, 16, 17,34, pl. 9
scopulosum, Sinum ,,,,,,,,,,,,,,,, 4, 5, 14,22, pl. 1
scopulosus, Sigaretus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 4
secta, Macoma ,,,,,,,,,, 6, 12, 14, 15, 19, 20,33, pl. 8
Securella ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 34
alaskensis ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 34
ensi era ____________________ 4, 6, 14, 15, 33, pl. 9

securis, Chione -_ -
Seiku ,,,,,,,,,,,,,

 

Semicassis ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
aequisulcatum ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 22
pyshtensis ,,,,,,,,,, 4, 5, 11, 14, 15, 20,22, pl. 1
centiquadrata ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 23
mm ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 22

 

 

 

Shark teeth _________________________________ 4
Sigaretus scopulosus __________________ ..__ .. 4
siletzensis, Cancellaria ____________ 5, 11, 15,25, pl. 2
simplex, Cancellaria ______________ 5, 12, 15,25, pl. 2
Sinum scopulosum ________________ 4, 5, 14,22, pl. 1
Slip Point ______________ 3, 7, 8, 9, 12, 18, 19, 21, 23,
24,27, 28, 30, 34
slipensis, Priscofusus ____________ 4, 5, 15, 20,24, pl. 2
Snavely, Parke D. Jr,, cited ______________________ 29
snavelyi, Solamen ______________ 4, 5, 14, 20, 29, pl. 4
Sohl, N. F., cited ________________________________ 2O
Solamen ____________________________________ 18, 29
porterensis ____________________________ 29, pl. 4
snavelyi ____________________ 4, 5, 14, 20, 29, pl. 4
Solemya ....

 
 
 
 

Solemyidae. .
Solen

 

 

 

 

 

Solenidae
Sooke Formation, fauna_-__
Vancouver Island ...... 21, 22, 24, 25, 26, 30, 31
sookensis, Clinocardium __________________________ 31
Crepidula _________________________________ 22
Macoma ,,,,,,,,,,,,,,,, ..-. 6, 14, 33, pls. 7, 8
Spisulu ________________ 6, 10, 13, 14, 16,31, pl. 6
Trochita ____________________________________ 21
Species, index __________________________________ 27
Spencer Creek, Lincoln County, Oreg ____________ 25
spirata, Trochita _______________ __ .- _______ 21
Spirotropis washinglonensis _____ _.__ ....... 26
Spisula ________________________________________ 31
albaria ________ 4, 5, 14, 15, 31, pls. 6, 7
goodspeedi ,,,,,,,,,,,, 5, 10, 14, 31, pls. 6, 7
catilliformis ________________________________ 31
equilateralis ________________________________ 31
hannibali ______________ 5, 10, 13, 14, 16,31, pl. 6
sookensis ______________ 6, 10, 13, 14, 16, 31, pl. 6
sp __________________________________ 6, 31 , pl. 6
Stanford University collections __________________ 20

stewarti, Priscnfusus ____ 5, 10, 11, 15, 16, 24,25, pl. 2
submontereyana, Anadara . _ _

 

 

substriata, Xylotrya ______________________

substriatum, Dentalium ,,,,,,,,,,,,,,,,,,,,,,,,,, 4

subtenta, Cyclocardia _________ 5, 14, 15,30, pls. 5, 6
quadrata, Venericardia ______________________ 30

supramontereyensis, Yoldia ,,,,,, 4, 5, 14, 19, 27, p11 3

Surian molluscan province ,,,,,,,,,,,,,,,,,,,,,, 20

T
Taylor, D. W., cited ,,,,,,,,,,,,,,,,

 
  
 
 
 
 
 
  
  
  
  
 
  
       
     
 

teglandae, Ancistrolepis Clarki -
Tellina arctata
arctata juana --
clallamensis .......
emacerata ,,,,,,,,,,
oregonensis -__
(Oudardia) sp
Tellinids ..........
Tellinidae ........
Temblor Formation _
Temblor Stage .......
central California
tenuissima, Yoldia _
Teredo bulbosus ....

 
 
  

sp ..........
Thesbia antiselli
Thracia ........
condoni ....
schencki ..... 6, 10, 13, 14, 16, 17,34, pl. 9
trapezoides ... -. 6, 14, 15, 18, 19,34, pl. 9
Thraciidae .......
Thyasiridae ..............
tichanovitchi, Mytilus .. 5, 13, 14, 16, 19, 20,28, pl. 5
trapezoides, Thracia ........ 6, 14, 15, 18, 19, 34, pl. 9
trochiformis, Trochita .......... .. 21
Trachita ............................ _ 19, 20
filosa ........................ . 21
inornata ........... _. 4
sookensis .................................... 21

44

 

 

 

   
 

 

Page

Trochita—Continued
spirata ______________________________________ 21
troc hiformis ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 2 1
n. sp ,,,,,,,,,,,,,,,,,,,,,, 5, 14, 15, 20, 21, pl. 1
Trophonopsis ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 23
sp ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5, 23, pl. 2
Trophosycon clallamensis ______ 5, 14, 15, 23, pls. 1, 2
kernianum ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 23
Turner, D. L., cited 0, ,,,,,,,,,,,,,,,,,,,,,,, 27
Turridae ____________________________________ 26
Turritella _,__ _____________________________ 21
oregonensis , __________________ 5, 14,21, pl. 1
yaquinana", ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 7
Turritellidae ____________________________________ 21
Twin River __________________________________ 32, 34
Twin River Formation ______________ 1, 3, 6, 7, 9, 16,
28, 3 , 2, 33, 34
age ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 7
benthonic foraminiferal assemblages ,,,,,,,,,, 18
contact ______________________________________ 16
depositional environment ________________ 18, 20
fauna] hiatus ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 16
molluscan assemblages ________________________ 7
mollusks __________________________________ 2, 7

twinensis, Macoma 1, 6, 10, 11, 13, 14, 16,32, pls. 6, 7
U

Ungulinidae ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 30

 

 

 

 

 

 
 

INDEX
Page
U.S.G.S. fossil localities ,,,,,,,,,,,,,,,,,,,,,, 19, 35
V
Vancouver Island ________________________________ 21
British Columbia, Canada ,,,,,, 22, 24, 26, 31, 33
Vaqueros Formation ___________________ ____ 31
Vaqueros Stage ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 20, 35
California ____________________ 12, 13, 16, 17, 18
Venericardia subtenta quadrata __________________ 30
Veneridae _____________________________________ 33
ventricosa, Archarax ___________________________ 28
Venus Clallamensis _______________________ 34, pl. 9
olympidea ___________________________ 34, pl. 9
(Chione) angustifrons u, 4
clallamensis ,,,,,,,,, 4
olympidea _______________________________ 4
Vertipecten fucanus ________________ 4, 5, 10, 13, 14,
15, 16, 17, 27, 29, pl. 4
sp ______________________________________ __ 17
victorianus, Palinices ,,,,,,,,,,,,,,,, 5, 14, 22, pl. 1
uokesi, Natica ,,,,,,,,,,,,,,,,,,,,,,,, 5, 14,22, pl. 1
Volutidae ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 25
W
Washington ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 24
depositional cycle ______
molluscan province ,,,,,,,,,,,,,,,,,,,,,,,, 2, 3

 

 

 

 

 

Page
washingtanensis, Spirotropis ,,,,,,,,,,,,,,,,,,,,,, 26
wattsi morani, Pecten (Chlamys) __________________ 4
Weaver, C. E., cited ______________________________ 27
weaveri, Musashia ______________________________ 17
whitneyi, Dosinia ____________________ 6, 14, 33, pl. 8
willapaensis, Archarax __________________________ 28
workensis, Ophiodermella ________________________ 26
wynaocheensis, Cancellaria _______ 5, 12, 15, 26, pl. 2
Megasurcula ,,,,,,,,,,,,,,,,, 5, 15, 19,27, pl. 3

X
Xenuraturris antiselli ,,,,,,,,,,,,,, 5, 15,26, pls. 2, 3
Xylotrya substriata ________________________________ 4

Y
Yakataga Formation, Gulf of Alaska ,,,,,,,,,, 31, 34
yakamgense, Clinocardium ______________________ 31
yakatagensis, Cyclocardia ________________________ 30
yaquinana, Bruclarkia ,,,,,,,,,,,, 5, 14, 15, 23, pl. 2
Turritella ___________________ __A 7
Yoldia ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27

impressa __________________________
reagani ___________________________

supramantereyensis W .1, 4, 5, 14, 19,27, pl, 3
tenuissima ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 27

Z
Zemorrian Stage ________________________________ 16

 

 

PLATES 1—9

Contact photographs of the plates in this report are available, at cost, from US. Geological Survey
Library, Federal Center, Denver, Colorado 80225.

 

 

FIGURES

2, 3.

4, 5, 20, 24.

6, 7.

8, 13.

9, 12, 18.

10, 11, 17.

14—16.

19, 27, 28.

21, 26.
23.
25.
29, 30.

31.

1, 22.

PLATE 1

[All specimens are from the Clallam Formation]

Crepidula praerupta Conrad.

1. Length 43 mm, width 24 mm. USNM 215926. USGS 10c. M5886.

22. Length 22 mm, width 18 mm. USNM 215927. USGS 10c. M4050.
Semicassis pyshtensis, n. Sp.

Holotype. Height 42 mm, width 28 mm. USNM 215928. USGS loc. M4414.
Neverita jamesae Moore.

4, 5. Height 20 mm, width 24 mm. SUPTC 10182. SU loc. NP161.

20, 24. Height 11 mm, width 15 mm. USNM 215929. USGS 10c. M4684.
Crepidula princeps Conrad.

6. Length 42 mm, width 26 mm. USNM 215930. USGS loc. M5886.

7. Length 37 mm, width 19 mm. USNM 215931. USGS 10c. M4414.
Epitonium clallamense Durham.

8. Height 24 mm, width 14 mm. USNM 215932. USGS 10c. M4413.

13. Height 28 mm, width 18 mm. USNM 215933. USGS 10c. M4413.
Trochita n. sp. Moore.

9. Height 11 mm, width 31 mm. USNM 215934. USGS loc. M4678.

12. Height 14 mm, width 32 mm. USNM 215935. USGS loc. M4681.

18. Height 9 mm, width 20 mm. USNM 215936. USGS 10c. M4049.
Turritella oregonensis (Conrad).

10. Height 18 mm, width 4 mm. USNM 215937. USGS 10c. M4049.

11. Height 18 mm, width 8 mm. USNM 215938. USGS loc. M4049.

17. Height 14 mm, Width 8 mm. USNM 215939. USGS loc. M4049.
Natica vokesi Addicott.

14, 15. Height 17 mm, width 19 mm. USNM 215940. USGS loc. M4680.

16. Height 13 mm, width 14 mm. USNM 215941. USGS 10c. M4680.
Natica cf. N. clarki Etherington.

19. Height 15 mm, width 18 mm. USNM 215942. USGS 10c. M5886.

27. Height 7 mm, width 9 mm. USNM 215943. USGS 10c. M4681.

28. Height 12 mm, width 13 mm. USNM 215944. USGS loc. M5886.
Sinum scopulosum (Conrad).

Height 13 mm, width 19 mm. USNM 215945. USGS 10c. M4678.
Crepidula sp.

Height 10.5 mm, width 16 mm. USNM 215946. USGS 10c. M4683.
Polinices victorianus Clark and Arnold.

Height 16 mm, width 17 mm. USNM 215947. USGS loc. M4681.
Ficus modesta (Conrad).

Height 53 mm, width 40 mm. USNM 215948. USGS Ioc. M4678.
Trophosycon clallamensis (Weaver).

Height 78 mm, width 55 mm. SUPTC 10183. SU 100. NP89.

GEOLOGICAL SURVEY PROFESSIONAL PAPER 976 PLATE 1

 

31

CREPIDULA, SEMICASSIS, NEVERITA, EPITONIUM, TROCHITA, TURRITELLA,
NA TICA, SINUM, POLINICES, FICUS, TROPHOSYCON

FIGURES 1—3.

4, 6, 19.

5, 7—9.

10, 11.

12.
13.

14, 17, 18, 21.

15.
16.
20.
22.
23, 25.
24.

26—28.

29.

30, 31.

32, 35, 38.

33.

34.

36, 37.

PLATE 2

[Specimens are from the Clallam Formation unless otherwise specified]

Bruclarkia oregonensis (Conrad).

1. Height 40 mm, width 30 mm. USNM 215949. USGS 10c. M4678.

2, 3. Height 43 mm, width 28 mm. USNM 215950. USGS loc. M4678.
Bruclarkia cf. B. oregonensis (Conrad).

4. Height 29 mm, width 19 mm. USNM 215951. USGS 100. M 4051.

6. Height 24 mm, width 15 mm. USNM 215952. USGS loc. M4051.

19. Height 23 mm, width 13 mm. USNM 215953. USGS loc. M4050.
Bruclarkia yaquinana (Anderson and Martin).

5. Height 34 mm, width 30 mm. SUPTC 10184. SU loc. NP89.

7. Height 25 mm, width 17 mm. USNM 215954. USGS loc. M4050.

8. Height 22 mm, width 15 mm. USNM 215955. USGS loc. M4050.

9. Height 17 mm, width 17 mm. USNM 215956. USGS 10c. M4051.
Molopophorus newcombei (Merriam).

10. Height 29 mm, width 16 mm. USNM 215957. USGS loc. M4060, Sooke Formation,

lower Miocene, southwest coast of Vancouver Island, British Columbia.
11. Height 34 mm, width 18 mm. USNM 215958. USGS 10c. M4060, Sooke Formation,
lower Miocene, southwest coast of Vancouver Island, British Columbia.

Priscofusus af‘f. P. geniculus (Conrad).

Height 28 mm, width 16 mm. USNM 215959. USGS loc. M4049.
Priscofusus slipensis, n. sp.

Holotype. Height 27 mm, width 16 mm. UW 13337. UW loc. 490.
Priscofusus goweri, n. sp.

14. Paratype. Height 16 mm, width 8 mm. USNM 215960. USGS loc. M4049.

17. Paratype. Height 18 mm, width 8 mm. USNM 215961. USGS loc. M4049.

18. Holotype. Height 18 mm, width 8 mm. USNM 215962. USGS loc. M4049.

21. Paratype. Height 23 mm, width 12 mm. USNM 215963. USGS loc. M4049.
Priscofusus cf. P. stewarti (Tegland).

Height 19 mm, width 13 mm. USNM 215964. USGS loc. M4049.
Molopophorus n. sp. aff. M. newcombei (Merriam).

Height 26.5 mm, width 18 mm. USNM 215965. USGS loc. M5879.
Trophonopsis sp.

Height 10 mm, width 6 mm. USNM 215966. USGS loc. M4677.
Xenuroturris antiselli (Anderson and Martin).

Height 11 mm, width 6 mm. USNM 215998. USGS loc. M4683.
Crepidula rostralis (Conrad).

Length 27 mm, width 19 mm, height 13.5 mm. USNM 215967. USGS loc. M4051.
Crepidula praerupta Conrad.

Length 22 mm, width 18 mm, height 15 mm. USNM 215967. USGS loc. M4050.
Cancellaria cf. C. oregonensis Conrad.

26. Height 14 mm, width 7 mm. USNM 215969. USGS loc. M4675.

27, 28. Height 13 mm, width 7 mm. USNM 215970. USGS loc. M4049.
Cancellaria cf. C. siletzensis Hanna.

Height 19 mm, width 11.5 mm. USNM 215971. USGS loc. M4049.
Cancellaria cf. C. simplex Anderson.

30. Height 23 mm, width 17 mm. USNM 215972. USGS loc. M4049.

31. Height 24 mm, width 17 mm. USNM 215973. USGS loc. M4049.
Cancellaria wynoocheensis Weaver.

32. Height 16 mm, width 16 mm. USNM 215974. USGS loc. M4049.

35. Height 19.5 mm, width 13.5 mm. USNM 215975. USGS 10c. M4049.

38. Height 23 mm, width 14.5 mm. USNM 215976. USGS loc. M6375.
?Rectiplanes sp.

Height 17.5 mm, width 8 mm. USNM 215977. USGS 10c. M4049.
Trophosycon clallamensis (Weaver).

Height 22 mm, width 21 mm. USNM 215978. USGS loc. M4051.
Cancellaria birchi Addicott.

Height 12 mm, width 6 mm. USNM 215979. USGS loc. M5879.

GEOLOGICAL SURVEY PROFESSIONAL PAPER 976 PLATE 2

 

36

 

BRUCLARKIA, MOLOPOPHOR US, PRISCOFUSUS, TROPHONOPSIS, CREPIDULA,
CANCELLARIA, RECTIPLANES, TR OPHOS YCON

FIGURES

4, 6, 10, 12—14.

7, 15.

8, 9.
11.
16, 17.

18—20, 22.

24, 25.

21, 23.

26.

27.

1—3.

PLATE 3

[Specimens are from the Clallam Formation unless otherwise specified ]

Acila conradi (Meek).
1. Length 19 mm, height 16 mm. SUPTC 10185. SU loc. NP163.
2. Length 21.5 mm, height 19 mm. USNM 215980. USGS 10c.
M4681.
3. Length 22 mm, height 19 mm. USNM 215981. USGS 10c. M4681.
Nuculana calkinsi (Moore).
4. Length 17 mm, height 10 mm. USNM 215982. USGS 10c. M4677.
6. Length 14 mm, height 8.5 mm. USNM 215983. USGS loc.
M4677.
10. Length 30 mm, height 18 mm. USNM 215984. USGS loc. M4049.
12, 13. Length 19.5 mm, height 11 mm. USNM 215985. USGS 10c.
M5878.
14. Length 16 mm, height 10 mm. USNM 215986. USGS loc. M4049.

. Archarax dalli (Clark).

Length 61 mm, height 22 mm. USNM 215987. USGS loc. M4050.
Yoldia supramontereyensis Arnold.
7. Length 41 mm, height 27 mm. USNM 215988. USGS 10c. M4680.
15. Length 24 mm, height 13 mm. USNM 215989. USGS 10c. M4680.
N uculana cf. N. elmana Etherington.

Length 21 mm, height 12 mm. USNM 215991. USGS loc. M6375.
N uculana chehalisensis (Weaver).

Length 14 mm, height 8 mm. USNM 215990. USGS loc. M4678.
Megasurcula cf. M. wynoocheensis (Weaver).

Height 31 mm, width 15 mm. UW 13339. UW loc. 490.
Ophiodermella olympicensis, n. sp.

18. Holotype. Height 16 mm, width 6.5 mm. USNM 215992. USGS
loc. M4051.

19. Paratype. Height 14.5 mm, width 8 mm. USNM 215993. USGS
loc. M4051.

20. Paratype. Height 11.5 mm, width 8 mm. USNM 215994. USGS
loc. M4051.

22. Paratype. Height 17 mm, width 8 mm. USNM 215995. USGS 10c.
M4051.

Ophiodermella cf. 0. olympicensis Addicott, n. sp.

24. Height 20 mm, width 8 mm. USNM 215996. USGS 10c. M2514,
Astoria Formation, lower or middle Miocene, Grays River
quadrangle, southwestern Washington.

25. Height 14 mm, width 8 mm. USNM 215997. USGS loc. M2514,
Astoria Formation, lower or middle Miocene, Grays River
quadrangle, southwestern Washington.

Xenuroturris antiselli (Anderson and Martin).
21. Height 11 mm, width 6 mm. USNM 215998. USGS loc. M4683.
23. Height 13 mm, width 6 mm. USNM 215999. USGS 10c. M4683.
Ancistrolepis rearensis (Clark).
Height 47 mm, width 28 mm. UW60271. UW 100. 490.
M usashia indurata (Conrad).
Height 74 mm, width 34 mm. USNM 216000. USGS loc. M4050.

GEOLOGICAL SURVEY PROFESSIONAL PAPER 976 PLATE 3

 

24

ACILA, NUCULANA, ARCHARAX, YOLDIA, MEGASURCULA, OPHIODERMELLA,
XENUROTURRIS, ANCISTROLEPIS, MUSASHIA

PLATE 4

[Specimens are from the Clallam Formation unless otherwise specified ]

FIGURES 1, 2, 5, 7, 10, 12. Vertipecten fucanus (Dall).
1. Length 64 mm, height 68 mm. USNM 216001. USGS 10c.
M4049.
2. Length 79 mm, height 75 mm. USNM 216002. USGS 10c.
M4414.
5. Length offragment 56 mm. USNM 216003. USGS loc. M4678.
7. Length 46 mm, height 44 mm. USNM 216009. USGS loc.
M4049.
10. Length 51 mm, height 60 mm. USNM 215968. USGS-10c.
M4678.
12. Length 80 mm, height 85 mm. USNM 216004. USGS loc.
M4049.
3, 11. Solamen porterensis (Weaver).
Length 10 mm, height 12 mm. USNM 216005. USGS 10c. 18977,
Lincoln Creek Formation, upper Oligocene, Grays Harbor basin,
southwestern Washington.
4, 8. Dentalium pseudonyma Pilsbry and Sharp.
4. Length 28 mm, width 6 mm. SUPTC 10188. SU loc. NP89.
8. Length 19 mm, width 4 mm. USNM 216006. USGS 10c. M4049.
6, 9. Solamen snavelyi, n. sp.
6. Paratype. Length 14 mm, height 19 mm. USNM 216007. USGS
10c. M4050.
9. Holotype. Length 14 mm, height 21 mm. USNM 216008. USGS
10c. M4051.

PROFESSIONAL PAPER 976 PLATE 4

GEOLOGICAL SURVEY

 

VER TIPECTEN, SOLAMEN, DENTALIUM

FIGURES 1, 2, 16, 18.

4, 7, 15.

8, 9.

10.
11.
12.
13.

14.

17.

PLATE 5

[Specimens are from the Clallam Formation unless otherwise specified ]

Mytilus n. sp. aff. M. tichanovitchi Makiyama.
1. Length 42 mm, height 82 mm. SUPTC 10189. SU loc. NP89.
2. Length 36 mm, height 84 mm. SUPTC 10190. SU loc. NP89.
16, 18. Length 38, height 102 mm. SUPTC 10191. SU loc. NP89.

. Glycymeris sp.

Length 27 mm, height 26 mm. USNM 216010. USGS loc. M4684.
Lucinoma acutilineata (Conrad).
4. Length 26 mm, height 23 mm. USNM 216011. USGS loc. M4050.
7. Length 38 mm, height 35 mm. SUPTC 10192. SU 10c. NP163.
15. Length 33 mm, height 32 mm. USNM 216012. USGS loc. M4414.

. Modiolus n. sp.? aff. M. restorationensis Van Winkle.

Length 29 mm, height 56 mm. USNM 216013. USGS loc. M4050.

. Anadara cf. A. devincta (Conrad).

Length 40 mm, height 29 mm. USNM 216014. USGS loc. M4678.
Anadara aff. A. lakei (Wiedey).
8. Length 40 mm, height 32 mm. USNM 216015. USGS loc. M4050.
9. Length 32 mm, height 27 mm. USNM 216016. USGS 10c. M4050.
Anadara devincta (Conrad).
Length 44 mm, height 32 mm. USNM 216017. USGS loc. M4678.
Dentalium schencki Moore.
Length 38 mm, width 8 mm. USNM 216018. USGS loc. M4049.
Cyclocardia subtenta (Conrad).
Length 21 mm, width 20 mm. USNM 216019. USGS loc. M5878.
Clinocardium n. sp. aff. C. nuttalli (Conrad) Moore.
Length 38 mm, width 36 mm. USNM 216020. USGS loc. M4681.
Mytilus tichanouitchi Makiyama.
Length 135 mm, height 79 mm. USNM 216021. Ashai Formation,
Miocene, central Hokkaido, Japan (Kanno and others, 1968).
Felaniella sp.
Length 22 mm, height 22 mm. USNM 216022. USGS loc. M4413.

PROFESSIONAL PAPER 976 PLATE 5

GEOLOGICAL SURVEY

 

MYTIL US, GL YCYMERIS, LUCINOMA, MODIOL US, ANADARA, DENTALIUM,
CYCLOCARDIA, CLINOCARDIUM, FELANIELLA

PLATE 6

[Specimens are from the Clallam Formation unless otherwise specified ]

FIGURES 1, 16. Spisula sookensis Clark and Arnold.
1. Length 64 mm, height 57 mm. USNM 216023. USGS loc. M4049.
16. Length 81, height 70 mm. SUPTC 10193. SU loc. NP89.
2, 4, 13, 15. Macoma twinensis Clark.
2, 4. Length 31 mm, height 22 mm. USNM 216024. USGS loc. M4032.
Upper member of the Twin River Formation, lower Miocene,
western Washington,
13, 15. Length 26 mm, height 18 mm. USNM 216025. USGS 10c.
M4032. Upper member of the Twin River Formation, lower
Miocene, western Washington.
3. Spisula albaria (Conrad).
Length 54 mm, height 46 mm. USNM 216026. USGS loc. M4051.
5. Macoma cf. M. twinensis Clark.
Length 23 mm, height 14 mm. USNM 216027. USGS loc. M4677.
6. Spisula sp.
Length 65 mm, height 48 mm. USNM 216028. USGS loc. M4049.
7. Conchocele disjuncta Gabb.
Length 43 mm, height 51 mm. USNM 216029. USGS 10c. M4050.
8. Clinocardium n. sp. aff. C. nuttalli (Conrad) Moore.
Length 43 mm, height 43 mm. USNM 216030. USGS loc. M4049.
9, 10. Cyclocardia subtenta (Conrad).
9. Length 20 mm, height 20 mm. USNM 216031. USGS loc. M4049.
10. Length 15 mm, height 15 mm. USNM 216032. USGS loc. M4677.
11. Spisula cf. S. hannibali Clark and Arnold.
Length 65 mm, height 46 mm. USNM 216033. USGS loc. M4675.
12. Solen conradi Dall.
Length 43 mm. height 13 mm. USNM 216034. USGS loc. M4050.
14. Spisula albaria goodspeedi Etherington.
Length 58 mm, height 49 mm. USNM 216035. USGS loc. M4414.

GEOLOGICAL SURVEY PROFESSIONAL PAPER 976 PLATE 6

16

 

SPISULA, MACOMA, CONCHOCELE, CLINOCARDIUM, CYCLOCARDIA, SOLEN

PLATE 7

[Specimens are from the Clallam Formation unless otherwise specified]

FIGURES 1. Spisula albaria goodspeedi Etherington.
Length 49 mm, height 40 mm. USNM 216036. USGS loc.
M4049.
2, 3, 11. Spisula albaria (Conrad).

2, 3. Mactra gibbsana Meek of Reagan (1909). Length 55 mm,
height 40 mm. USNM 32832. Probably from the east side
of Clallam Bay near Slip Point.

11. Length 31 mm, height 25 mm. USNM 216037. USGS loc.

M4051.
4, 6, 8, 14, 18, 22. Macoma arctata (Conrad).
4. Length 52 mm, height 31 mm. USNM 216038. USGS loc.
M4051.
6. Length 41 mm, height 25 mm. USNM 216039. USGS loc.
M4051.
8. Length 50 mm, height 32 mm. USNM 216040. USGS loc.
M5886.
14. Holotype of Tellina arctata var. juana Reagan (1909).
Length 55 mm, height 33 mm. USNM 328319. Near Slip
Point.
18. Length 45 mm, height 28 mm. USNM 216041. USGS 10c.
M4049.
22. Length 61 mm, height 35 mm. USNM 216042. USGS 10c.
M4049. '
5, 7, 10. Tellina emacerata Conrad.
5. Length 37 mm, height 21 mm. USNM 216043. USGS loc.
M4684.
7. Length 32 mm, height 18 mm. USNM 216044. USGS 10c.
M4051.
10. Holotype of Tellina clallamensis Reagan (1909). Length 33
mm, height 19 mm. USNM 328320. Near Slip Point.
9. Macoma cf. M. astori Dall.
Length 38 mm, height 28 mm. USNM 216045. USGS 10c.
M4049.
12. Macoma twinensis Clark.
Length 34 mm, height 23 mm. USNM 216048. USGS loc.
M4032. Upper member of the Twin River Formation, lower
Miocene, western Washington.
13—15, 17, 20. Macoma albaria Conrad.

13, 17, 20. Length 22 mm, height 15 mm. USNM 216046. USGS

10c. M4050.

14, 15. Length 17 mm, height 12 mm. USNM 216047. USGS 10c.

M4677.
16, 19. Macoma arnoldi Tegland.
Length 32 mm, height 26 mm. USNM 216049. USGS loc.
M4042. Blakeley Formation, upper Oligocene, Restoration
Point, Washington.
21. Macoma astori Dall.
Length 52 mm, height 46 mm. USNM 216050. USGS loc.
M4049.
23. Macoma sookensis Clark and Arnold.
Length 54 mm, height 41 mm. SUPTC 10194. SU loc. NP161.

PROFESSIONAL PAPER 976 PLATE 7

GEOLOGICAL SURVEY

 

SPISULA, MA COMA, TELLINA

PLATE 8

[Specimens are from the Clallam Formation unless otherwise specified]

FIGURES 1, 2, 5. Macoma sookensis Clark and Arnold.
1. Length 58 mm, height 43 mm. SUPTC 10195. SU loc. NP161.
2. Length 50 mm, height 48 mm. USNM 216051. USGS 10c. M4681.
5. Length 49 mm, height 38 mm. USNM 216052. USGS loc. M4681.
3. Macoma flagleri Etherington.

Length 44 mm, height 31 mm. USNM 216053. USGS loc. M1495, As—
toria Formation, lower or middle Miocene, Grays Harbor basin,
southwestern Washington.

4. Macoma n. sp. Moore.
Length 46 mm, height 42 mm. USNM 216054. USGS loc. M4683.
6. Macoma n. sp. aff. M. secta (Conrad).
Length 41 mm, height 30 mm. USNM 216055. USGS loc. M4678.
7, 8, 11~18. Katherinella angustifrons (Conrad).
7. Inflated form. Length 31 mm, height 30 mm. USNM 216056. USGS
loc. M4677.
8, 1 1. Thin form. Length 37 mm, height 35 mm. USNM 216058. USGS
loc. M4049.

12. Length 40 mm, height 36 mm. SUPTC 10196. SU 10c. NP163.

13. Length 58 mm, height 45 mm. USNM 216057. USGS loc. M4051.

14, 16. Thin form. Length 41 mm, height 41 mm. USNM 216059. USGS

loc. M4050.

15, 17. Inflated form. Length 46 mm, height 43 mm. USNM 216060.

USGS 10c. M4050.
18. Thin form. Length 64 mm, height 57 mm. USNM 216061, USGS loc.
M4049.
9, 10. Dosinia whitneyi (Gabb).
9. Length 25 mm, height 22 mm. USNM 216062. USGS loc.
M4684.

10. Length 30 mm, height 31 mm. USNM 216063. USGS loc.
M4683.

GEOLOGICAL SURVEY PROFESSIONAL PAPER 976 PLATE 8

 

17

MACOMA, KA THERINELLA, DOSINIA

PLATE 9

[All specimens are from the Clallam Formation]

FIGURES 1—3, 5, 6, 9, 10, 13. Securella ensifera (Dall).
1. Length 55 mm, height 51 mm. USNM 216064. USGS 10c.
M4678.
2. Length 42 mm, height 36 mm. USNM 216065. USGS 10c.
M4683.
3. Holotype of Venus clallamensis Reagan (1909). Length 43
mm, height 34 mm. USNM 328312. Near Slip Point.
5. Length 49 mm, height 47 mm. SUPTC 10197. SU 100. NP89.
Length 49 mm, height 40 mm. SUPTC 10198. SU loc. NP89.
9. Length 39 mm, height 39 mm. USNM 216074. USGS 10c.
M4049.
10. Length 33 mm, height 32 mm. USNM 216066. USGS loc.
M4051.
13. Holotype of Venus Olympidea Reagan (1909). Length 35 mm,
height 31 mm. USNM 328311.
4, 12. Thracia trapezoides Conrad.
4. Length 59 mm, height 45 mm. SUPTC 10199. SU 10c. NP163.
12. Length 34 mm, height 30 mm. USNM 216067. USGS 10c.
M4051.
7, 8, 16. Panopea abrupta (Conrad).
7. Length 53 mm, height 37 mm. USNM 216068. USGS loo.

9‘

M4678.

8. Length 50 mm, height 28 mm. USNM 216069. USGS loc.
M4683.

16. Length 78 mm, height 42 mm. USNM 216070. USGS 10c.
M4050.

11, 14. Thracia cf. T schencki Tegland.

11. Length 35 mm, height 23 mm. USNM 216071. USGS 10c.
M4051.

14. Length 33 mm, height 20 mm. USNM 216072. USGS 10c.
M4051.

15. Panopea ramonensis (Clark).

Length 82 mm, height 43 mm. USNM 216073. USGS 10c.

M467 8.

\

GEOLOGICAL SURVEY PROFESSIONAL PAPER 976 PLATE 9

 

SECURELLA, THRACIA, PANOPEA

GPO 692-104

 

 

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Stratigraphic distribution of some pollen

types from the Campanian and lower

Maestrichtian rocks (Upper Cretaceous)
mm of the Middle Atlantic States

IIENCES

 

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UNIV" LIBRARY
cRSlTY 0F CALIFORNII
X

  
    

   

Stratigraphic distribution of some pollen
types from the Campanian and lower
Maestrichtian rocks (Upper Cretaceous)
of the Middle Atlantic States

By JACK A. WOLFE

 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 977

 

 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1976

UNITED STATES DEPARTMENT OF THE INTERIOR
THOMAS S. KLEPPE, Secretatjv

GEOLOGICAL SURVEY

V. E. McKelvey, Director

Library of Congress Cataloging in Publication Data

Wolfe, Jack A. 1936—

Stratigraphic distribution of some pollen types from the Campanian and lower Maestrichtian rocks (Upper Cretaceous) of
the Middle Atlantic States.

(Geological Survey Professional Paper 977)

Bibliography: p.

Supt. of Docs. no.: 119.162977

1. Pollen, Fossil. 2. Paleobotany—Cretaceous. 3. Paleobotany~Middle Atlantic States. I. Title. II. Series: United States.
Geological Survey Professional Paper 977.

QE993.2.W64 560'.13 76—608052

 

For sale by the Superintendent of Documents, U.S. Government Printing Oflice
Washington, DC. 20402

Stock Number 024-001~02816-6

CONTENTS

Abstract __________________________________________________
Introduction ______________________________________________
Geologic occurrence ________________________________________
Biostratigraphy
Significance to lithostratigraphic units ______________________
Correlations with pollen assemblages from the Mississippi

embayment

Page
1
1
1
3
7

Page
Correlations with pollen assemblages from the Cape Fear

arch ____________________________________________________ 9
Paleoecology ______________________________________________ 9
Significant pollen types ____________________________________ 11
Fossil localities ____________________________________________ 17
References cited __________________________________________ 17

ILLUSTRATIONS

[Plates follow references]

PLATE 1. Campanian and Maestrichtian pollen, NA—l—NH—l.
2. Campanian and Maestrichtian pollen, NJ—l—PR—7.
3. Campanian and Maestrichtian pollen, C3A—1—CP3B—5.
4. Campanian and Maestrichtian pollen, CP3B—6—MPI—1.
Page
FIGURE 1. Map of the sample locations in the Middle Atlantic States ____________________ 2
2. Post-Magothy Cretaceous rock sections ______________________________________ 3
3. Graph showing abundance of major pollen types ______________________________ 10
TABLES
Page
TABLE 1. Stratigraphic distribution of selected taxa of dicotyledonous pollen in the Campanian
and Maestrichtian rocks of the Middle Atlantic States ________________________ 4
2. Comparison of ages predicted on the basis of climatic cycles with radiometric ages in
Campanian and Maestrichtian rocks of the Middle Atlantic States ____________ 11

III

 

 

 

STRATIGRAPHIC DISTRIBUTION OF SOME
POLLEN TYPES FROM THE CAMPANIAN AND
LOWER MAESTRICHTIAN ROCKS (UPPER CRETACEOUS)
OF THE MIDDLE ATLANTIC STATES

' A. WOLFE

ABSTRACT

Analysis of 74 pollen samples from the Cliffwood beds of the upper
part of the Magothy Formation and from the younger marine Creta-
ceous rocks indicates that 10 informal biostratigraphic subdivisions
can be made of this Campanian and lower Maestrichtian section.
Comparison of these subdivisions in the northern Raritan embayment
with those in the southern Salisbury embayment indicate that the
Woodbury Clay in the north is a facies of the upper part of the
Merchantville Formation to the south. The pollen data can be inter-
preted to support the concept that the lower part of the Mount Laurel
Sand in the south is the biostratigraphic equivalent to the Wenonah
Formation in the north. The “Matawan” previously recognized on the
west shore ofChesapeake Bay is shown to be “Monmouth” and equiva-
lent in age to part of the Navesink Formation of the Monmouth Group.
The biostratigraphic subdivisions proposed form the basis for correla-
tions of the Late Cretaceous rocks of the Mississippi embayment with
those ofthe Atlantic Coastal Plain. Fluctuations in the relative abun-
dance of bisaccate coniferous pollen are interpreted as climatic fluctu-
ations. A total of 104 dicotyledonous pollen types are briefly discussed
and illustrated.

INTRODUCTION

The difficulties of correlating the Campanian and
Maestrichtian (Upper Cretaceous) rock units on the At—
lantic Coastal Plain have been amply discussed by Sohl
and Mello (in Owens and others, 1970). The marine
faunas contain few ammonites, and many of the faunas
contain long-ranging taxa or are of low diversity.
Further, because of preservational factors, determina-
ble mollusks are uncommon in many of the units. It was
thought, therefore, that pollen studies might provide a
supplementary and more consistent means of correlat-
ing these rocks. Some pollen assemblages had, in fact,
been described from these rocks (Gray and Groot, 1966),
but the described taxa were few, and some of the sam-
ples were obviously stratigraphically misplaced (Owens
and others, 1970), particularly those from the
Chesapeake and Delaware Canal.

In 1969 an extensive series of samples was collected
for analysis. These samples, which were collected with
the assistance of J. P. Minard, J. P. Owens, and N. F.
Sohl, were supplemented with a few samples collected
earlier by Owens and Sohl. The productivity of the sam—

ples was remarkable; of the 58 samples collected from
these marine horizons, 57 contained determinable
material. With the exception of the Tinton Sand, all the
Campanian and Maestrichtian units have produced pol—
len assemblages. In addition, the assemblages of the
upper part of the Magothy Formation have been pre—
liminarily studied based on 17 samples; these samples
are also of Campanian age.

For their advice and assistance on various aspects of
this study, I wish to thank E. B. Leopold, J. P. Minard,
J. P. Owens, N. F. Sohl, and R. T. Tschudy.

GEOLOGIC OCCURRENCE

In the Middle Atlantic States, the Campanian and
Maestrichtian rocks occur in a belt extending from
northeastern New Jersey south to the vicinity of
Washington, DC. (fig. 1). Studies ofthese rocks (Owens
and others, 1970) indicate that the depositional history
in the northern area—the Raritan embayment (central
and northern New Jersey)——was somewhat different
than in the southern area—the Salisbury embayment
(Maryland, Delaware, and southern New Jersey). Sev-
eral of the units can be traced from one embayment to
the other, but other rock units are present in only one
embayment (fig. 2). Whether the absence of some litho-
stratigraphic units is due to facies changes and time
transgressive phenomena cannot be certainly deter-
mined without resort to paleontologic work.

Older studies (for example, Clark, 1916) divided the
Campanian and Maestrichtian rocks into two basic
units: the Matawan Formation (or Group) and the
Monmouth Formation (or Group), the Matawan of sup-
posed Campanian age and the Monmouth of supposed
Maestrichtian age. Further, the underlying Magothy
Formation was considered to be of Turonian age and
unrelated to these other units. From the east shore of
Chesapeake Bay and north, Owens, Minard, Sohl, and
Mello (1970) have shown that the subdivision into

 

Matawan and Monmouth along the age-stage boundary

1

2 STRATIGRAPHIC DISTRIBUTION POLLEN, CAMPANIAN AND MAESTRICHTIAN ROCKS

 

l

0 10 20 3O

 

40 MILES
m I l | I
I I I I I I T
0 10 20 30 40 50 60 KILOMETRES
40° - +

PENNSYLVANIA

   
   
      
 

"7 . . I314. ,4,, 11‘
"unnssamfras

 

‘8
4
I:- o
1>\.121o

’11
9,.

39°

 

'I

'I

i. DELAWARE
'I

I

     
 
       
       
    
 
  
  

l

"217,1 215

O
"219 "222w

I
“221 1112111224

"223 . .11225
.1122, 11225

’ '11229

  

NEW JERSEY

 

75 74“

FIGURE 1.—General location of sampling sites in the Coastal Plain of the Middle Atlantic States. Numbers refer to USGS paleobotany
localities, details for which are given in the section on "Fossil localities.”

is simplistic and that much of the “Monmouth” is, in
fact, of Campanian age. Further, the upper part of the
Magothy Formation (the Cliffwood beds and equivalent
horizons) has been shown to be of probable earliest
Campanian age (Wolfe and Pakiser, 1971). On the west
shore of Chesapeake Bay, where mapping has not yet
progressed to the stage where the units mapped by
Owens, Minard, Sohl, and Mello (1970) can be recog-
nized in most areas, the older terminology of Matawan
and Monmouth is still applied.

About half the samples were collected from central
and northern New Jersey and represent all the Campa-
nian and Maestrichtian units except for the Mount

 

Laurel Sand (the one sample collected from this unit
was barren) and the Tinton Sand. In eastern Maryland,
Delaware, and southern New Jersey, all the units rec-
ognized by Owens, Minard, Sohl, and Mello (1970) pro-
duced pollen assemblages. On the west shore of
Chesapeake Bay, the supposed Matawan was sampled,
but, as discussed in the section on “Biostratigraphy,”
this Matawan is equivalent in age to part of the
Navesink Formation and is thus assignable to the
Monmouth.

The Campanian-Maestrichtian boundary recognized
in this report (within the Navesink Formation) is based
on the work of Sohl and Mello (in Owens and others,

BIOSTRATIGRAPHY 3

 

 

 

 

 

 

 

 

 

 

 

 

 

MN
I)?
0°19
e
’70
Red Bank Sand
ANV Mon outh
11225 m““°“ Forrrrl‘ation 11210
1 11212
11223{ 5"“,‘90
W
11212 (
Mount Laurel Sand
- _ 11233
< Wenonah Formatlon 11234.11213
11225 ' n
atlo
11 FM“ - 11230
11361 - Marshautow "”6
1 560“
0
? 11231
115““)
1|226{ _ 11174
9‘9 - 11173
01%
d _ 11172
yo
11221 0 0 WW
{ $° go
\
«0
.\\\°
11211 e
.500
6'
11219 $9
11213 -W

 

 

FIGURE 2.—Genera1ized sections of the post-Magothy Cretaceous
rocks of the Middle Atlantic States. A, New Jersey; B , Delaware
and eastern Maryland; C, Western shore of Chesapeake Bay.
Numbers indicate approximate stratigraphic position of
localities. A and B modified from Owens and Minard (in Owens
and others, 1970).

1970). Other workers, specialists in planktonic Fora-
minifera in particular, would place the boundary lower,
probably at or near the base of the Mount Laurel Sand.

BIOSTRATIGRAPHY

Six major divisions are proposed for Campanian to
lower Maestrichtian rocks of the Raritan and Salisbury
embayments; the divisions are based on the strati-
graphic ranges of dicotyledonous pollen (table 1). Four
of these major divisions have recognizable subzones;
thus a total of 10 informal biostratigraphic units are
recognized. A sequence of informal palynologic zones for
the Potomac Group and Raritan Formation, which has
been proposed (for example, Brenner, 1963), are num-
bered sequentially in roman numerals. Although it
might be desirable to continue the numbering sequence
for the zones discussed in this report, the number of
zones between the Raritan and Magothy Formations
cannot now be determined and the Magothy pollen
floras need further study to determine the zonation.

Considering the unknown number of zones that may

 

eventually be recognized between the Raritan Forma-
tion and the rock units of Campanian age, I have started
a new numbering sequence prefixed by “CA,” which
stands for Campanian, and “MA,” which stands for
Maestrichtian. Subzones within the major zones are
denoted by suffixes, for example, “A” for the lowest
subzone. Zone 6, which is of both Campanian and Maes-
trichtian age, has the prefix CA—6/MA—1.

The fact that most zonal and subzonal boundaries
proposed here are approximately coincidental with
lithostratigraphic boundaries (table 1) may be a reflec-
tion of incomplete sampling across lithostratigraphic
boundaries. For example, one of the most distinct as-
semblages, that of Zone CA—4, is based on samples from
the middle part of the Englishtown Formation. Had the
lower and upper parts of the Englishtown been sampled,
Zone CA—4 might not appear as palynologically distinc-
tive as described in this report. However, in the instance
of the boundary between Zones CA—l and CA—2, the
assemblage from 11217—H at the top of the Magothy
Formation is clearly distinct from that from 11218 at
the base of the Merchantville; the latter assemblage,
nevertheless, does have features intermediate between
the uppermost Magothy assemblage and the as-
semblages from the middle part of the Merchantville
(11219—A—F). The differences between the assemblages
such as those from 11217—H and 11218 may reflect a
definite hiatus; indeed, a sharp disconformity separates
the Magothy and Merchantville (Owens and others,
1970).

Zone CA—I and older Magothy strata—Pollen as-
semblages from the Magothy Formation have been dis-
cussed and partly illustrated elsewhere (Wolfe and
Pakiser, 1971). Additional samples not reported on be-
fore have been studied to a limited extent, but the work
has not progressed to the stage of presentation other
than to indicate that the Magothy sequences in the
Raritan embayment appear different than those in the
Salisbury embayment. I emphasize that these sugges-
tions may be premature. The Magothy sequence in the
Raritan embayment (in descending order) appears to be:

Cliffwood beds (Zone CA—l): Normapolles-
dominated assemblage that has some strong
similarities to the Merchantville, particularly
the basal Merchantville.

Morgan beds (Santonian): Similar to the
Cliffwood, as well as to the Amboy stoneware
clay.

Amboy Stoneware Clay Member (Santonian):
Normapolles dominated, but greater diversity
than in Morgan beds.

Old Bridge Sand Member (Coniacian?): Conifer
dominated (bisaccates), low diversity of Nor-
mapolles (Pseudoplicapollis, Trudopollis,

STRATIGRAPHIC DISTRIBUTION POLLEN, CAMPANIAN AND MAESTRICHTIAN ROCKS

TABLE 1.—Stratigraphic distribution of selected taxa of dicotyledonous pollen

SALISBURY EMBAYMENT

POLLEN SPECIES

 

 

 

 

 

 

 

 

FORMATIONSAND HNN mmh HNMHNMMNM—(N HNM .4... HNMHNHHNHNEQV'LD .4—1 -<—n
IIITIII?|IIII llll ”T anIIHNHNIII IIIIIIIIfiNIIF‘F‘IIF‘“m “w"
MWAMTES <<<<<<<<mmmoodmoaméémémkkwELAAAMMM$5Ezzoooooédcmééb>ééégééé
ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZmemmmmm
1‘ + + + f
i + + i 5 + ,+ +
i + + + + + + + z + a a
f + 1“ + i + a i a + 5 1?
Inn—H ++ 5 + + 5 i + + + + i .5 ++ 3
11212-6. ; g 5 § 5 H; 2 + 5 i a 5 E g 5 5
11210—12 + 5 + 5 a s s E + 5 + + 5 5+ E 5
11212“: 5 + 5 5 5+ 5 + 5 5 E 5 5 5 5 5
11210—0 : a s a 2+ 5 + 5 s a s 2: 2 5
Monmouth “ZN—E 5 5‘5- 5 ‘5' 5 '5' 5 5 5
Formation 11212—1) 5 5 5 5 5+ 5 + 5 5 5 5 5+ 5 5
11210—0 5 3 g 5 5+ 5 a s E i E 5 5 5 5
11212—c g i 5 z s g + + 5 g a g 5
11212-8 a s 5 i i a i a 5 a i .= a
11210-13 5 § 5 5 5 E 5 E 5 E 5 5 5
11212—A § 5 5 3 s g + g + i 5 § 5
1121o-A g g 5 + 5 5 + + 5 E 5 E ,5
i i a + + i + +- g + + +
E 5‘ 5 5 Jr 3 + 5 z E
Mount Laurel Sand 11233 + i i i + + ++ +- ++ +§ g E +
+ E + ++ + + +: ++ ++ ii 5 5: + 5
+ é + 5+ + + .= 3 ++ +5 +a.+ i i 5 + +
a s 3 5 E i + 5;f +5 +5 +5 3 § a+ i it
C + + + 5+ 2 + i 5 s 2 a s a a g+++ a +
FY5235; 11213 B 5 + 5+ +5 + ‘5' +5 5 5 +5 5 5 +4." 5 ‘5' '5'
A + 5 +5 5+ 1* 5 5+ +4: 5+ §+ + ,5 T
Marshalltown 11234 I + + + 4-— +
Formation . . E E : :+ ++ : ‘f‘ :
11230 + s . a 2+ ++ ++ + s +
11176 +5 ' , 5 5 + 5 +5 5 5 + 5
Englishtown + + 5 _ + 5 .f'. + + + + + .1. +
Formation + +— + 5 5 3 + +. E 1- g
1’ + .+ . 5 . . 5 + + ++ 5 1L 7‘ +
+ + :5 5+ + 2 + +
a '2 5+ 5 5 5 5
F ‘5‘ 5 ‘5’+. + 5 5 5' +
E + 5 ++ ‘5' + + 5
D + 5 2+ 2 + +
11231 c + 5 ++ 5 E 5
B + 5 +4: 5 5 5
A 1‘ 5 5+ + 5 5
Jr E ++ 5 + + 1'
+ a 5+ 2 + +
t 5 5+ + +
'5' 5 +5 5
+ a + 6+
5' 5 5 1’ 5+
+ + 5 s + 9+
+ s s' + + i
Merchantville i + + I
Formatlon + + §+ + +
11174 5 + s + 5+ 5 +
11173 a + . s + 5+ 5 5
11172 5 5 +. 5 + 5 5 5 5
“155 ‘5 5 ‘5' E E ++ 5 g
+ ++ + + 1- ++ + + + + +
11228,11229.11232 +4» + 4'- 4'-
Magothy Formation

 

Plicapollis, Complexiopollis) and Trisectoris.
In the Salisbury embayment, the Magothy samples
from exposures in the Chesapeake and Delaware Canal
and at Florence Bluffs contain assemblages that are
very similar palynologically to the Cliffwood as-
semblages. The assemblages from the Magothy on the
Severn River (a short distance from the type Magothy)
are not directly comparable to any assemblages from

samples from the Raritan embayment Magothy. The
Severn River Magothy has a low diversity of Normapol-
les types, although somewhat greater than in the Old
Bridge. Unlike the low occurrences in the Old Bridge,
Normapolles are common in the Severn River Magothy,
along with an assemblage of tricolpate and triocolporate
types; some of these types are found in the Amboy
Stoneware Clay member. On this basis, I suggest that

BIOSTRATIGRAPHY

in the Campanian and Maestrichtian rocks of the Middle Atlantic States

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

POLLEN SPECIES RARITAN EMBAYMENT

HNmHvam‘DDwHNHNMHv-{NF‘

l I I || I IHflH NMH HHN
T‘M’TTTTTTTTTT<<<ééééédédéonnoéééwgIIgéélzééir FORMATIONSAND SUB ZONE STAGE
<<<<<mmmmUOOOMmmmmnnmmmmmmmmmmmmm ”no W “ LOCALITIES ZONE
«anammmmmmmmmmmmmmmmamammmmmmmmmmmmmmmmmmmmmm
oooooooooooooooooouoooo0000000000222222222222 z

+ +1. + .1.- 11224 Red Bank Sand B E
+ E §+ ' i c g a
1}. + 5 +3 + 1311223 "‘ 3 2
a i E H- , A 05
E +3 +5 ,3 w
: i : g : +: [g
: : 1 ' 3 - E <
a a 5 +5 +5 2
?
Navesink _ _
g 3 Formation A CA (“MA 1
i i 4%
é a e i i a +
a 3 a 3+ + +
g 4 + 2 B a
5 + 3 + A11222 E
+ + Mount Laurel Sand a
1- ti + C
3 +3 3 B 11225 Wenonah
E +' + A Formation B CA—5
+ +e a +
+ +: + E + ———?--—?-—-?-—-
+ ++ +
+. 5 Marshalltown “--
+: + 11351 Formation A
+§ __ _______ _z
,5 + + S
+ =f- + + + c Englishtown CA-4 z
‘l‘ 5 i B 11226 Formation 4:
+ + + + ++ A E
+ + 4'- i '3 B — _______ <1
+ E + §+ A11221 B U
= g + + + a
a a a + ———
+ + i +
E + E 3 Woodbury _
a E + 5 Clay CA3
2 + + +
+ + + a + D A x
i +2 + a + C
+ a 'a + 3 + Bum E
. z + §+ + + = = A o
1 . 2 2+ 2 ++ G ’ ‘ g
. i s a E i F
:+ + : 3 + D1121!)
§+ + i + C Merchantville
5+ g a a + B . B CA-2
:+ E A Formation
5+ '5 + +
5+ E ': +-
+2 5 + +
++ i 2 ___
+ + + + 11218
+ 4. 11217,A-H ___:_—
Magothy Formation CA 1

the Severn River Magothy (and probably the type sec-
tion of the Magothy) represents the interval between
the sampled Old Bridge and the sampled Amboy Stone-
ware. This in turn indicates the possibility that the
Magothy Formation as now recognized in the Salisbury
embayment may represent two units separated by an
hiatus. The stratigraphy at the Salisbury embayment
appears to be more complicated than heretofore

thought. It should be pointed out that the samples of
Cliffwood age in the Salisbury embayment typically
contain dinoflagellates and thus they may represent
estuarine conditions. Marine mollusks, as well as di-
noflagellates, occur in the Cliffwood beds at Cliffwood
Beach, and dinoflagellates were found in some samples
from the Morgan beds.

Zone CA—2.—Zone CA—2 encompasses the Mer-

6 STRATIGRAPHIC DISTRIBUTION POLLEN, CAMPAN IAN AND MAESTRICHTIAN ROCKS

chantville Formation. A sample (11218) from the basal
Merchantville immediately above the contact with the
Cliffwood beds at Cliffwood Beach contains at least 10
pollen species not yet found in samples from the
Cliffwood beds (11217—A through G). This basal Mer-
chantville sample, however, also contains three species
that occur in the Cliffwood but not in other Mer-
chantville samples. Particularly significant is the fact
that, as in the Cliffwood samples, “Proteacidites” is lack-
ing in 11218 but the probable pre-“Proteacidites”
(NQ—l) is present. On this basis, the basal Mer-
chantville beds at Cliffwood Beach, from which 11218
was collected, are recognized as Subzone CA—2A, as
distinguished from the Merchantville samples from the
Oschwald pit (11219A through G), in which “Proteaci—
dites” is present in most samples and NQ—l is absent in
all. Further, at least 12 species are found in the Osch-
wald Merchantville but not in 11218 or the Cliffwood
beds. Analyses of samples from the interval between
11218 and 11219—A (approximately middle part ofMer-
chantville), might show the compositions between
11218 and other Merchantville samples to intergrade.

The Merchantville Formation exposed in Maryland
and Delaware was sampled at four localities (11172,
11173, 11174, and 11231). The pollen assemblages from
three of these localities (11172, 11173, 11174), corres-
pond well with Subzone CA—ZB. At 11231, (samples
A—F) in the upper part of the Merchantville along the
Chesapeake and Delaware Canal, the pollen as-
semblages do not correlate with the Oschwald Mer-
chantville; as discussed below, these Merchantville
samples that represent Zone CA—3, are from an age
equivalent of the Woodbury Clay. Indeed, Owens,
Minard, Sohl, and Mello (1970) indicate that along the
Sassafras River, the Merchantville grades upward into
the Englishtown Formation and the Woodbury Clay is
absent. Such data clearly indicate that the age equiva-
lent of the Woodbury Clay is here within either the
Merchantville or the Englishtown, and the pollen data
indicate that the Woodbury equivalent is within the
Merchantville. More recently, Minard (1974, p. 20) has
revised earlier concepts on the supposed pinching out of
the Woodbury in southern New Jersey, proposing that
the Woodbury is present (but coarser than to the north)
and was erroneously included in the upper part of the
Merchantville. The molluscan evidence within the Mer-
chantville exposed in the canal section indicates that
possibly the Woodbury Clay equivalent is absent (Sohl
and Mello in Owens and others, 1970), but Sohl (oral
commun., 1975) considers the molluscan data based on
new collections to be equivocal in determining the pres-
ence or absence of a Woodbury equivalent.

A sample (11156) from the east shore of Maryland on
Elk Neck is also from Subzone CA—2B. Although the

 

beds from which this sample was collected had previ-
ously been assigned to the Magothy Formation (Owens
and others, 1970), the palynologic data strongly indi-
cate an age equivalent of the Oschwald Merchantville.
Owens (oral commun., 1975), moreover, states that the
assignment of these Elk Neck beds to the Magothy was
uncertain and that these beds could, on geologic
grounds, represent either Merchantville or Eng-
lishtown, as well as Magothy.

Zone CA—3.—This zone includes the Woodbury Clay
of central and northern New Jersey and the upper part
of the Merchantville Formation in the Salisbury em-
bayment. At least 10 species occur in samples 11227 (A
through D; lower part of Woodbury) and not in the
Oschwald Merchantville (11219). An additional four
species occur in samples 11221 (A and B; upper part of
Woodbury) and not lower in the section. In addition,
four species range from the Oschwald Merchantville up
into the lower part of the Woodbury but not into the
upper part. On this basis, the lower part of the Wood-
bury Clay is assigned to a subzone (CA—3A) distinct
from that (CA—3B) of the upper part. In the upper part of
the Merchantville exposed in the Chesapeake and Del-
aware Canal (locality 11231), samples A—D in partic-
ular bear a strong resemblance to assemblages char-
acterizing Subzone CA—3A, whereas sample D and
particularly sample E more closely resemble the as-
semblages from Subzone CA—3B.

Zone CA4.—Three samples (11226—A through C)
from the middle part of the Englishtown Formation in
the Raritan embayment and one sample (11176) from
the Englishtown of the Salisbury embayment all closely
resemble one another and concomitantly are highly dis-
similar from samples from higher or lower units. Ten
species are restricted to the Englishtown, eight have
their lowest occurrence in this unit, and nine have their
highest occurrence. According to Sohl and Mello (in
Owens and others, 1970), the Englishtown Formation is
probably of latest early Campanian age.

Zone CA—5.—This zone includes the Marshalltown
Formation, Wenonah Formation, and at least the lower
part of the Mount Laurel Sand. More than 20 species
have their lowest occurrence in this zone, whereas 11
species that occur lower in the section have their last
occurrence. Six species have their highest occurrence in
the Marshalltown Formation, six have their lowest oc-
currence, and two are restricted to this unit; on this
basis, the Marshalltown assemblages form the basis for
Subzone CA—5A. An additional 10 species have their
highest occurrence in the Wenonah or Mount Laurel,
whereas six species have their lowest occurrences in
these units, which are assigned to Subzone CA—5B. On
the basis of present data, it would be difficult, if not
impossible, to distinguish between the pollen as-

SIGNIFICANCE TO LITHOSTRATIGRAPHIC UNITS 7

semblages from the Wenonah Formation and the one
assemblage from the lower part of the Mount Laurel.
Indeed, Sohl and Mello (in Owens and others, 1970)
suggest that the lower part of the Mount Laurel in the
canal section (from which the one Mount Laurel pollen
sample was obtained) may in fact represent the time
equivalent of the Wenonah to the north in New Jersey.
The pollen data are consistent with such an interpreta-
tion.

Zone CA—6/MA-1.—This zone includes the Navesink
Formation and at least the basal part of the Red Bank
Sand in the Raritan embayment. In the Salisbury em-
bayment, the Monmouth Formation exposed at Round
Bay on the Severn River falls within this zone. At least
18 species are known in this zone but not in lower zones;
the upward extent of the ranges of many of these species
is not known.

Subdivisions of this zone are not entirely satisfactory.
A considerable number of species are known only in the
Red Bank, but as only one Red Bank sample has been
examined, the stratigraphic significance of these
species (most of which are not discussed or illustrated in
this report) is uncertain. The samples from the upper-
most part of the Navesink closely resemble those from
the lowermost part: of the 22 uppermost Navesink
species, for example, 18 occur in the lowermost
Navesink. Although reliance on a single lineage may be
tenuous, NK—2 is consistently found through 11223—B
in the uppermost Navesink, Whereas NK—3 occurs in
1 1223—C and in the Red Bank. Lending some support for
a biostratigraphic division between 11223—B and
11223—C is the fact that 11 species are known through
11223—B but are not known in either 11223—C or the
Red Bank. Although admittedly tentative, the upper-
most Navesink sample and the Red Bank sample form
the basis for Subzone CA—6/MA—1B (this subzone is, of
course, entirely of Maestrichtian age), whereas the
samples lower in the Navesink form the basis for Sub—
zone CA—6/MA—1A.

The Monmouth Formation along Severn River con-
tains several species that have not yet been found in the
New Jersey section. Of the species common to both sec-
tions, the Severn River Monmouth clearly correlates
with Subzone CA—6/MA—1A. Four of the Severn River
species are not known in the upper Navesink or Red
Bank; three are not known in the lower Navesink or
older samples. In general, the Monmouth Formation
along Severn River would appear to be approximately
equivalent to the middle part of the Navesink Forma-
tion, although age equivalents of both the upper (but not
uppermost) and lower Navesink could be represented.
The ammonite found in the upper part of the Severn
River Monmouth is a species that, in New Jersey, is
restricted to the upper Navesink and Red Bank.

 

SIGNIFICANCE TO
LITHOSTRATIGRAPHIC UNITS

Owens and Minard (in Owens and others, 1970) con-
sider that the Woodbury Clay of New Jersey thins
southwestward and is absent in the Chesapeake and
Delaware Canal section. Minard (1974) has revised this
interpretation; he suggests that the Woodbury may lose
its identity by a facies change to the south. The
palynologic data indicate that beds of Woodbury age
(Zone CA—3) are present in the canal section in the
upper part of the Merchantville Formation, that is, the
upper boundary of the Merchantville is time-
transgressive (or the Woodbury Clay is a facies of the
upper part of the Merchantville).

Along the Sassafras River, the upper part of the Mer-
chantville (but not the uppermost part) contains as-
semblages assignable to Zone CA—2B. Possibly beds of
Woodbury age are present here; this could be deter-
mined with certainty if the uppermost Merchantville
were sampled.

Owens, Minard, Sohl, and Mello (1970) state that the
Mount Laurel Sand in the Chesapeake and Delaware
Canal grades downward into the Marshalltown Forma-
tion, the intervening Wenonah Formation having
thinned out in southern New Jersey. The palynologic
data could be interpreted to substantiate this conclu-
sion; the assemblage from the lower part of the Mount
Laurel in the canal assemblage does not differ signific-
antly from the Wenonah assemblages. In order to sub-
stantiate this interpretation with certainty, it would
first be necessary to determine if the Mount Laurel
pollen assemblage in central and northern New Jersey
were recognizably younger than the one assemblage
from the Mount Laurel in the canal. Unfortunately, the
one barren sample collected was from the Mount Laurel
in northern New Jersey.

Owens and Minard (in Owens and others, 1970) indi-
cate that the Navesink Formation thins southward
from northern New Jersey and is absent in the section
along the east shore of Chesapeake Bay. On the west
shore, however, rocks equivalent in age to the Navesink
are well represented along the Severn River. Further,
although the upper part of the Merchantville along the
Chesapeake and Delaware Canal is equivalent in age to
the Woodbury Clay (Zone CA—Z), to the west along the
Sassafras River the upper part of the Merchantville is
equivalent in age to the Merchantville of northern New
Jersey (Zone CA—2); to this time, no rocks of Zone CA—3
have been determined along Chesapeake Bay. As dis-
cussed earlier in this report, the Magothy Formation
exposed along the Severn River appears to be older than
the Magothy Formation exposed along the Chesapeake
and Delaware Canal and in southern New Jersey. Fi-
nally, rocks in southern New Jersey and Maryland tra-

8 STRATIGRAPHIC DISTRIBUTION POLLEN, CAMPANIAN AND MAESTRICHTIAN ROCKS

ditionally assigned to the Raritan Formation have been
shown to represent the uppermost part of the Potomac
Group, and beds of an age equivalent to the Raritan
Formation of northern New Jersey are apparently ab-
sent in outcrop in southern New Jersey, Delaware, and
Maryland (Doyle, 1969; Wolfe and Pakiser, 1971). The
depositional history of the Raritan embayment thus
appears to be significantly different from the deposi-
tional history in the Salisbury embayment (particularly
in the areas now adjacent to Chesapeake Bay).

CORRELATIONS WITH POLLEN ASSEMBLAGES
FROM THE MISSISSIPPI EMBAYMENT

A large number of species of the Normapolles com-
plex has been described by Tschudy (1975) based on ma-
terial from the Mississippi embayment. Additionally,
Tschudy has allowed me to compare the Atlantic Coast-
al Plain assemblages with illustrations of unpublished
assemblage plates from various samples from the Cam-
panian and Maestrichtian rocks of the embayment.

Two points of disagreement exist between the ages
suggested here for the Mississippi embayment as-
semblages and the ages assigned to the assemblages by
Tschudy (1975). First, the sampled Coffee Sand of Ten-
nessee clearly correlates with the Englishtown Forma-
tion (Zone CA—4), whereas Tschudy (1975) assigned the
Coffee Sand to the upper Campanian and considered his
sample to be younger than samples from the Cusseta
Sand Member of the Ripley Formation (Zone CA—5).
Tschudy’s sample (D3412) is stated to be from the mid-
dle part of the type section of the Coffee Sand; the
suggested correlation of these rocks with the lower
Campanian Englishtown Formation is in accordance
with correlations proposed by Sohl (1964a, 1964b) and
Sohl and Mello (in Owens and others, 1970). Sohl con-
siders only the upper part of the Coffee Sand to be
equivalent to the lower part of the Cusseta Sand
Member, the remainder of the Coffee Sand being of
early Campanian age. Second, Tschudy (1975) assigns
the Coon Creek Tongue of the Ripley Formation to the
Maestrichtian. The data in this report support the opin-
ion of Sohl (in Owens and others, 1970) that the Coon
Creek Tongue is of late Campanian age.

The placement of Tschudy’s sample D3412 from the
Coffee Sand in Zone CA—4 is based on the number of
species in common. The following forms illustrated in
this report also occur in D3412:

NA—l (CA—3B—CA—4)
NB—l (CA—2A—CA—4)
NC—l (CA—2B—CA—4)
ND—3 (CA—3A—CA—5B)
NE—l (CA—1—CA—5A)
NE—2 (CA—4—CA—5A)
NJ—2 (CA—4—CA6/MA—1A

 

 

NM—l (CA—4—CA—5B)

NO—l (CA—3B—CA—5B)

CP3B—5 (CA—4)

CP3E—l (CA—2B—CA—5B
The overlap of ranges of several species concomitant
with the occurrence of CP3B—5 indicate that D3412 is
assignable to Zone CA—4.

The following species occur in D3260 from the upper
part of the Cusseta Sand Member of the Ripley Forma-
tion in Alabama:

NA—8 (CA—5B—CA—6/MA—1B

NE—3 (CA—5A—CA—6/MA—1A)

NF—4 (CA—4—CA—5B)

N R—l (CA—5A)

PR—7 (CA—4—CA—6/MA—1B)

MPH—1 (CA—5A—CA—5B)
This assemblage is clearly indicative onone CA—5; Sohl
and Mello (in Owens and others, 1970) correlate the
Cusseta Sand member with the Marshalltown and
Wenonah Formations and the lower part of the Mount
Laurel Sand, a correlation in agreement with that
suggested here. Which subzone of Zone CA—5 D3260
should be placed in is not certain; NR—l would indicate
Subzone CA—5A, but the occurrences of this species are
so uncommon that I would prefer to rely on the range of
N A—8 and suggest that D3260 is from beds correlative
with the Wenonah Formation or the lower part of the
Mount Laurel Sand. In fact, NR—l is known in probable
CA—5B or CA—6/MA—1A samples in the Mississippi
embayment.

Sample D3413 from the Cook Creek Tongue of the
Ripley Formation in Tennessee contains the following
species:

NA—3 (CA—5B)

NA—8 (CA—5B—CA—6/MA—1B)

NC—2 (CA—2A—CA—5B)

NE—3 (CA—5B—CA—6/MA—1B)

NN—1 (CA—4—CA—5B)

NO—2 (CA—5A—CA—5B)

NT—l (CA—5B—CA—6/MA—1A)

CP3F—2 (CA—5B—CA—6/MA—1B)
The co-occurrence of these species is indicative of Sub-
zone CA—5B; that is, this part of the Cook Creek Tongue
is correlative with either the Wenonah Formation or the
Mount Laurel Sand. Sohl (1964a) and Sohl and Mello (in
Owens and others, 1970) correlate the Coon Creek in
Tennessee with the Mount Laurel Sand and the upper-
most part of the Wenonah Formation.

The McNairy Sand Member of the Ripley Formation
has yielded specimens of NN—2 (CA—6/MA—1A and B) at
locality D3358 and NA—8 (CA—5B—CA—6/MA—1B),
NG—l (CA—6/MA—1A), NK—2 (CA—6/MA—1A), and
MPH—2 (CA—6/MA—1A) at locality D1967. The correla-
tion indicated is of the bulk of the Navesink Formation

PALE OEC OLOGY 9

with the McNairy Sand Member; that is, the McNairy
can be assigned to Subzone CA—6/MA—1A. Sohl (1964a)
also correlated the McNairy with the bulk of the
Navesink.

The type locality of the Owl Creek Formation (D3410)

contains the following species:

NH—l (CA—6/MA—1A)

NK—3 (CA—6/MA—1B)

NO—3 (CA—6/MA—1A and B)

PR—7 (CA—4—CA—6/MA—1B)
The assignment to Zone CA—6/MA—1 is clear, and prob-
ably locality D3410 is in Subzone B of this zone. The
occurrence of NK—3, which is thought to be descended
from NK—2 in Subzone A, is considered to be more sig-
nificant than the occurrence of NH—l.

The basic similarity of the Atlantic Coastal Plain and
Mississippi embayment pollen sequences from Zone
CA—4 through Zone CA—6/MA—1B is strong evidence of
the overall validity of the proposed zonation. It would,
however, be desirable to sample the Mississippi em-
bayment section in more detail, particularly in the Cof-
fee Sand; presumably, the lower part of this unit would
produce assemblages assignable to Zones CA—1 through
CA—3. The correlations suggested here are in consistent
agreement with those suggested by Sohl and Mello (in
Owens and others, 1970, fig. 23).

CORRELATIONS WITH POLLEN ASSEMBLAGES
FROM THE CAPE FEAR ARCH

Sampling of the Cretaceous units of North Carolina
has been extremely limited; thus far, only two produc-
tive samples—both from the Black Creek Formation—
have been analyzed. The oldest sample, D5019 from
Walker’s Bluff on the Cape Fear River, contains the
following species:

NB—1 (CA—2A—CA—4)

ND—3 (CA—3A—CA—5B)

C3A—1 (CA—2A—CA—4)

CP3B—3 (CA—3A and B)
The placement of this sample is in Zone CA—3, although
it cannot be determined which subzone is represented.
The second sample, D5018 from Jessup’s Landing on the
Cape Fear River, contains the following species:

ND—3 (CA—3A—CA—5B)

NE—3 (CA—5A—CA—6/MA—1B)

NN—l (CA—4—CA—5B)

PR—7 (CA-4—CA—6/MA—1B)

C3B—3 (CA—5A—CA—6/MA—1B)
This sample is assignable to Zone CA—5, but, as with the
other Black Creek sample, the assemblage is too small
to determine which subzone is represented. Neverthe-
less, the palynologic data are consistent with the inver-
tebrate evidence (Sohl and Mello in Owens and others,
1970), which indicates that the Black Creek Formation

 

contains correlatives of the Woodbury Clay (Zone CA—3)
and Marshalltown and Wenonah Formations (Zone
CA—5).

PALEOECOLOGY

Most of the angiospermous pollen types found cannot
be related with certainty to extant families or even
orders, and this makes paleoecological interpretations
based on distributions of extant related taxa of little
value. One aspect of the various samples is notable: the
percentages of bisaccate pollen in both the Raritan em-
bayment and Salisbury embayment sections seem to
fluctuate sharply (fig. 3). The bisaccate pollen repre-
sents various coniferous genera, particularly those in-
cluded in Podocarpaceae and Pinaceae.

Two periods of deposition of abundant bisaccate pol-
len are apparent: one during Woodbury time (Zone
CA—3) and another during Marshalltown through part
of Navesink time (Zone CA—5 through part of CA—6/
MA—lA). In contrast during Cliffwood and Mer—
chantville time (Zones CA—l and CA—2) and Eng-
lishtown time (Zone CA—4), representation of bisaccate
pollen is low to moderate whereas pollen of the Nor-
mapolles complex is well represented. Apparently
another period of low bisaccate representation began in
the upper part of the section during Navesink time.

The fluctuations in relative abundance of bisaccate
pollen and Normapolles pollen have no obvious relation
to the sedimentary cycles proposed by Owens and
Minard (in Owens and others, 1970). For example, the
Merchantville and Marshalltown Formations both rep-
resent the initial transgressive phase of their respective
cycles, but the former has only a moderate representa—
tion of bisaccate pollen and the latter has a high rep-
resentation of this type of pollen. A second example is
that the Mount Laurel (high bisaccate) and English-
town (low bisaccate) both represent the closing phase of
their respective cycles. These examples indicate that
factors such as water depth or distance from shore have
little, if any, bearing on the pollen fluctuations.

If the sedimentary cycles have no relation to the pol-
len fluctuations, then possibly the fluctuations repre-
sent climatic changes, with the high bisaccate periods
representing cool intervals relative to the low bisaccate
periods. Such fluctuations in climate could represent
the same series of cycles suggested for the Tertiary
(Wolfe, 1971). In order to test this hypothesis, I calcu-
lated backward from the well-documented cooling that
occurred about 32 my. ago, assuming that each com-
plete cycle had a duration of 9.5 m.y. (Wolfe, 1971) and
that a warm period of a given cycle had the same dura-
tion as a cool period of that cycle. The predicted ages of
the warm and cool periods are given in table 2, as are the
radiometric ages on the various rock units (Owens and

10 STRATIGRAPHIC DISTRIBUTION POLLEN,

Raritan embayment

Bisaccate conifers

Normapolles

   
 

 
       

 

Zone or subzone
CAG/MA—IB

CA6/MA—1 A

CAMPAN IAN AND MAESTRICHTIAN ROCKS

Salisbury embayment

Bisaccate conifers Normapolles

/

11212

 

 

 

 

 

 

C
11226 B
A
{B
11221
A
c:
LI-I D
2
3 11227 C
B
LIJ
g A
< G
(I)
F
E
11219 D
C
B
A\
s
112111 .
H‘\
G
F
E
11217
D
C
B
A I I l I I I I I I
0 50 1000 50

FREQUENCY, IN PERCENT

FIGURE 3.—Relative abundance of certain major pollen types in the Campanian and Maestrichtian rocks of the Middle Atlantic States.

Based on counts of 200 pollen grains per sample. Lined areas,
simpler Normapolles types.

Sohl, 1973). The agreement between the predicted and
radiometric ages is extremely close and is certainly
within the experimental error of the radiometric ages. It
should be noted that the Magothy assemblages typically
have a 10W bisaccate representation, except for the Old
Bridge Sand Member assemblages from the base of the
Magothy. The Old Bridge, then, would apparently be
about 84 my old—the age predicted for the end of the
next oldest cool period.

The percentages of bisaccate and Normapolles pollen

the podocarpaceous Rugubiuesiculites; shaded areas, structurally

could be used in a general manner to indicate age in
local correlations. High Normapolles representation,
for example, occurs only in CA—4 and in CA—2 and older
beds. Another trend in these samples is the increasing
proportion of structurally simpler types of Normapolles
relative to the more complex types (for example, Pseu-
doplicapollis, Trudopollis, Plicapollis, Endoinfundibu-
lapollis). This increase is particularly apparent between
Zones CA—4 and CA—5 and continues during the sup-
posed cool period of Zone CA—5. One possible explana-

SIGNIFICANT POLLEN TYPES 11

TABLE 2.—Comparison of ages predicted on the basis of climatic cycles with radiometric ages in
Campanian and Maestrichtian rocks of the Middle Atlantic States
[Radiometric ages from Owens and Sohl (1973)].

 

Climate Rock unit (or subdivision)

Predicted age
(my)

Radiometric ages
(my)

 

Red Bank Sand
Navesink Formation, upper part
Navesink Formation, middle part

Warm

62.8:22, 63211.9

 

Navesink Formation, lower part
Mount Laurel Sand

Wenonah Formation
Marshalltown Formation

Cool

65.3

68.2-52.4, 71412.5

 

Warm Englishtown Formation

70.0

74.8

 

Cool Woodbury Clay

74.0:2.5
79.5

 

Merchantville Formation

Warm

80.7i4.0, 812:2.6

Cliffwood beds of Magothy Formation

Morgan beds of Magothy Formation
Amboy Stoneware Fire Clay Member

of Magothy Formation

 

Old Bridge Sand Member of

COO] Magothy Formation

84.3

 

tion is that, contrary to earlier speculation (Wolfe,
1973), the cooler climate of Zone CA—5 was an impetus
to the rise of the wind-pollinated amentiferous groups
from the Normapolles stock; at least some of the simpler
Normapolles types can be related to some extant ament-
iferous groups (see discussion of types NK and NN on
page 13).
SIGNIFICANT POLLEN TYPES

Rather than enter into the controversial area of
nomenclature of fossilized pollen, I have chosen to adopt
an expedient course of coding most of the pollen types.
Where previously described genera and species can be
recognized, the probably formal designation has been
pointed out. As Hughes (for example, Hughes and
Moody—Stuart, 1967) has exhaustively pointed out,
there has been a definite tendency for palynologists to
apply previously published names to new material that,
to a greater or lesser extent, differs from the type speci-
men or suite on which the names are based. This, in
turn, has led to apparently broad stratigraphic ranges,
not of great use in biostratigraphy. I readily admit that
some of the “code species” distinguished in this report
may not be of specific rank to some palynologists, but
the recognition of minor differences that appear to be
correlative with stratigraphic differences will, I hope,
make this report of more value to palynologists in-
terested in stratigraphy.

In this section of the report, the pollen types of ap—
parent stratigraphic, biogeographic, or evolutionary
significance are discussed. The pollen types have been

 

broken down into several major categories: the Nor-
mapolles complex (N), tricolpates (CB), tricolporates
(CP3), “Proteacidites” (PR), and miscellaneous pollen
types (MP). A letter immediately following the above
designations indicates that two or more genera are
taken to have been included in the overall designation
and the letters represent different genera. The number
following the dash indicates the different pollen species.

Not all the pollen types found in the current study are
discussed here or illustrated. Fern spores have been
ignored, and most gymnospermous and monocotyledon-
ous pollen; and though 104 dicotyledonous pollen types
are discussed and figured, at least an equal number that
were photographed in the surveys were found to be
typically rare and therefore ignored.

Type NA (Basopollis and Choanopollenites).—These
two genera are characterized by the presence of a dis-
tinct mesopore and a broad endopore; the wall complex
forming the mesopore protrudes toward the exopore. In
erecting Choanopollenites, Stover (in Stover and others,
1966) noted that Basopollis had a vestibulum, and, by
inference, Choanopollenites does not. From Stover’s
figure la on plate 5, a distinct (albeit weak) endopore is
apparent, and thus Choanopollenites does, in fact, pos-
sess a vestibulum. The only feature distinguishing the
two genera is that the wall complex forming the meso—
pore is thickened at the mesopore in Choanopollenites,
whereas the probably homologous wall complex in
Basopollis is of uniform thickness. Were I considering
formal nomenclatorial problems in this report, I would

12

consider Choanopollenites a junior synonym of
Basopollis.

Type NA—l (pl. 1, fig. 1) is closely similar to
Choanopollenites discipulus R. Tschudy from the late
Maestrichtian and Paleocene of the Mississippi em-
bayment (Tschudy, 1975). The Atlantic Coastal Plain
species, however, has a larger atrium, and the walls
forming the exopore are less thickened and less protrud-
ing than in C. discipulus. Type NA—l occurs in the
Woodbury and Englishtown. Tschudy (1973) suggested
that C. discipulus was derived from C. transitus R.
Tschudy, which in turn was derived from some species of
Complexiopollis. The Atlantic Coastal Plain sequence,
however, indicates that the C. discipulus type is in fact
older than the C. transitus type. Whether Choanopolle-
nites is directly derived from any type of Complexiopol—
lis is, I think, open to question. Choanopollenites has an
apertural structure fundamentally similar to that of-
Basopollis, which, as Goczan, Groot, Krutzsch, and
Pacltova (1967, p. 487) have shown, is most similar to
that ofPlicapollis. Further, Complexiopollis abditus R.
Tschudy, one of the possible ancestors for Choanopolle~
nites suggested by Tschudy (1973), is fundamentally
different from both Complexiopollis and Choanopolle-
nites. This species has equatorial thickenings of the
outer wall layer that extend toward the poles (so-called
arci), and these thickenings form the exopore (this is
evident from Tschudy’s photographs), not the mesopore
(as misinterpreted in Tschudy’s text-fig. 5); this species
is common in the Merchantville and Woodbury (see
discussion of type NB on page 00).

Type NA—2 (pl. 1, fig. 2) is similar to NA—3 (pl. 1, fig. 3;
Choanopollenites transitus R. Tschudy) except that the
outer wall is of consistent thickness, that is, there is no
tendency for the wall to be enlarged around the exopore.
Type NA—2, which is confined to the Englishtown and
Marshalltown, is apparently ancestral to NA—3. Type
N A—3 ranges from the Marshalltown-Wenonah transi- ‘
tion through the middle part of the Navesink. Type
NA—4 (pl. 1, fig. 4) is known only from the uppermost
part of the Severn River Monmouth; this type has the ‘
mesopore extending almost to the inner part of the exo-
pore (and hence the atrium is extremely small), bul-
bous, protruding ambs, and is larger than NA—2 and)
NA—3. Tschudy (1973, figs. 9—13) illustrated grains from i
the Paleocene Clayton Formation that conform to l
NA—4.

Type NA—5 (pl. 1, fig. 5) has been found in only one
sample from the upper part of the Severn River Mon-
mouth. Except for its smaller size, NA—5 is similar to
Choanopollenites sp. A of Tschudy (1973), which is
known from the Paleocene Clayton Formation. Type
NA—5 is perhaps ancestral to this Tertiary species.

Type NA—6 (pl. 1, fig. 6) from the Merchantville is the [

 

 

STRATIGRAPHIC DISTRIBUTION POLLEN, CAMPANIAN AND MAESTRICHTIAN ROCKS

oldest known Choanopollenites. The more rounded
ambs, larger atria, and more conspicuous radial baculae
distinguish NA—6 from NA—2. NA—7 (pl. 1, fig. 7) from
the Englishtown has thickened walls forming the exo-
pore, and radial baculae are very indistinct. Similar to
NA—7 but with conspicuous radial baculae is NA—8 (pl.
1, fig. 8; Wenonah through Red Bank.) Type NA—8 also
resembles C. conspicuus (Groot and Groot) R. Tschudy,
but C. conspicuous is larger and has a narrower meso-
pore.

Type NB.—As discussed above, this type is probably
not closely related to Complexiopollis. Type NB—l (pl. 1,
fig. 9; basal Merchantville through Englishtown) com—
pares well with ”Complexiopollis” abditus R. Tschudy.
Although Tschudy (1973) cited the range of"C. ” abditus
as Coniacian through upper Campanian, Wolfe and
Pakiser (1971) indicated that the Eutaw Formation,
from which Tschudy’s “Coniacian” sample came, is of
Santonian through earliest Campanian age, and Sohl
(in Owens and others, 1970) indicated that the Coffee
Sand, from which Tschudy’s ”late Campanian” sample
came, is of early Campanian age.

Type NB—Z (pl. 1, fig. 10) has, in the present study,
been found only in the basal Merchantville. Wolfe and
Pakiser (1971, fig. 5—m), however, reported the same
form from the Cliffwood beds of the Magothy Formation.
Type NB—3 (pl. 1, figs. 11, 12) differs from NB—Z by
having the thickenings of the wall extend farther to-
ward the poles; NB—3 closely resembles "Complexiopol-
lis” microverrucosus R. Tschudy, except that the latter
has the walls thickened around the exopore. Possibly
NB—3 is descended from NB—Z; NB—3 is known from the
upper part of the Merchantville through the upper part
of the Severn River Monmouth.

Type NC (Pseudoplicapollis).—At least three basic
types of NC can be distinguished. Type NC—l (p1. 1, fig.
13), which occurs from the Merchantville through the
Englishtown, is characterized by a thickened wall sur-
rounding the exopore; type NC—2 (pl. 1, fig. 14; Mer-
chantville through Wenonah), which was described by
Tschudy (1975) as P. endocuspis, has little or no en-
largement of the wall around the pore, and also has less
conspicuous plicae than NC—l. Type NC—3 (pl. 1, fig. 15)
has no enlargement of the wall around the pore, very
weak plicae, and a broad vestibulum; this type ranges
from the Merchantville through the Severn River
Monmouth.

Type ND.—This Normapolles type falls outside of the
bounds of previously described genera as circumscribed
by Géczan, Groot, Krutzsch, and Pacltova (1967). Type
ND is particularly close to Plicapollis but differs in that
the endopore is V-shaped or U-shaped inwardly- Type
ND—1 (pl. 1, fig. 16) is larger than ND—2 (p1. 1, fig. 17)
and has distinct sculpturing in contrast to the almost

SIGNIFICANT POLLEN TYPES

psilate condition in ND—2. ND—l is rare in the Mer-
chantville through Englishtown; ND—2 is rare but is
restricted to the Marshalltown and Wenonah.

Type ND—3 (pl. 1, fig. 18) typically has weakly de-
veloped Y-shaped thickenings and a broadly U- or
V-shaped endopore. This species is common from the
Woodbury through the Wenonah.

Type (NE) Plicapollis.——Several distinct types ofPlica—
polis have been recognized, but only four appear to be of
common occurrence. Type NE—l (pl. 1, fig. 19;P. rusticus
R. Tschudy) is common from the Magothy through the
Woodbury and occurs up into the Marshalltown. Type
NE—2 (pl. 1, fig. 20; P. retusus R. Tschudy) has been
found only in the Englishtown and Marshalltown, and
type NE—3 (pl. 1, fig. 21;P. usitatus R. Tschudy) ranges
from the uppermost Marshalltown through the
Navesink and the Severn River Monmouth. From this
stratigraphic distribution, it is tempting to suggest that
NE—l is the type ancestral to at least NE—3, which
differs primarily by its smaller size and thinner walls.

Type NE—4 (pl. 1, fig. 22) differs from NE—l by its
smaller size, thin walls, and round body. Type NE—2 has
conspicuous radial baculae on the interior of the exo-
pore. Type NE—4 is most similar to NE—3, but NE—3 has
a considerably larger atrium. Although NE—4 techni-
cally conforms to Plicapollis in pore structure, in other
characters it closely resembles Pseudoplicapollis (type
NC) and may be a species of this genus that has con-
verged with Plicapollis. To this time NE—4 is known
only from the lower part of the Merchantville.

Types NF (Trudopollis) and NM (Endoinfundibu-
lapollis).—NF (Trudopollis) and NM (Endoinfundibu-
lapollis) are treated together because they are linked by
intermediate forms. Type NF—l (pl. 1, figs. 23, 24) has an
endopore of varying width, and in some specimens (par-
ticularly from the higher part of the Merchantville; pl.
1, fig. 24) the vestibulum is large, apparently as a result
of the collapse of the inner wall(s) inward into the grain.
In NF—2 (pl. 1, fig. 25; restricted to the Woodbury), the
wall around the exopore is considerably thinner (as is
the wall elsewhere) than in NF—l, and the inner wall(s)
is pulled even more inward. In NM—l, (pl. 1, fig. 26),
which represents Tschudy’s (1975) type species of E ndo-
infundibulapollis, found from the Englishtown through
the Wenonah, the vestibulum is consistently larger
than in NF—2.

Type NF—3 (pl. 1, fig. 27) appears to represent a
distinct Trudopollis, but one that has no obvious ances-
tral type lower in the section. NF—3 has been found only
in the Mount Laurel.

Type NF—4 (pl. 1, fig. 28) is rare in the Englishtown
and Wenonah. In shape, size, and sculpturing, this
species appears to fall within Trudopollis variabilis R.
Tschudy.

 

13

Type NG Pseudatlantopollis.—Type NG (pl. 1, figs.
29, 30) appears to fall nearPseudatlantopollis simulatus
R. Tschudy. Tschudy, however, stated that the size
range of this species is 20—26 pm (based on 35 speci-
mens), whereas the two Navesink specimens are 29 and
32 ,um. The size difference, coupled with the somewhat
rounder shape of the Navesink grains, may indicate
that the Navesink species is new.

Type NH (Interpollis).—This species was included by
Tschudy (1975) as Interpollis cf. I. supplingensis. None
of the specimens from the Severn River Monmouth dis-
play an equatorial constriction and all possess a thick-
ened endopore; this morphologic consistency in the
Maryland material indicates that Tschudy’s (1975)
specimens figured on plate 4, figures 14, 15, probably
represent a species different from the other specimens
he referred to I. cf. I. supplingensis.

Whether NH—l (pl. 1, fig. 35) could be validly referred
to I nterpollis is highly questionable. The facts that arci
are absent and that it lacks an equatorial constriction
indicate that NH— probably represents a distinct genus.
Although both NH—l and I nterpollis have subequatorial
pores, other Normapolles genera and derivatives have
this tendency. It seems clear that Carya has developed
subequatorial pores independently, and that this
character, in itself, is not an indication of close rela-
tionship.

Type NI .—This Normapolles type has a pronounced
Y-shaped polar thickening that enlarges into occuli
around the pores. Of previously described genera, NI is
apparently closest to Bohemiapollis but lacks the long,
narrow canal of the exopore. NI—l (pl. 1, figs. 31, 32)
occurs in the basal Merchantville and in the Woodbury,
whereas NI—2 (pl. 1, figs. 33, 34) occurs in the English-
town. NI—2 differs by having asmaller atrium and
exopore.

Type NJ (Extremipollis).——One Woodbury sample
contains a small type ofExtremipollis (NJ—1; pl. 2, fig.,
1), the oldest known in North America or Europe. The
larger E. vivus R. Tschudy (NJ—2; pl. 2, fig. 2) occurs
from the Englishtown through the upper part of the
Navesink.

Type NK.——Goczan, Groot, Krutzsch, and Pacltova
(1967) have suggested that certain structures in the
grains of the extant Rhoiptelea are homologous with
similar structures in the Normapolles genus Com-
plexiopollis; by inference, therefore, Rhoipteleaceae
and the allied J uglandaceae could be considered as re-
licts of the Normapolles complex. Wolfe (1973)
suggested that certain pollen grains from the Severn
River Maestrichtian were assignable to Rhoipteleaceae
and J uglandaceae and had features indicative of a deri-
vation from the Normapolles complex. Further study
has now indicated the strong probability that both ex-

14

tant families of Juglandales are, in fact, derivatives
from certain Normapolles types.

A pollen type (NK—l pl. 2, fig. 3) restricted to the
Marshalltown, Wenonah, and Mount Laurel, is of defin-
ite Normapolles affinities, as indicated by the radial
baculae on the interior of the exopore. These grains
appear to be structurally less complex than Trudopollis,
which also has a somewhat thicker wall (particularly at
the exopore), larger vestibulum, and a narrower endo-
pore. Type NK—1 has a polar thinning on one hemis-
phere; this thin area is more conspicuous on grains with
somewhat thicker walls.

Grains (NK—2; pl. 2, fig. 4) from the Severn River
section of the Monmouth Group are slightly less aspi-
date than in NK—l, lack radial baculae on the interior of
the exopore, and have a somewhat thinner wall al-
though the same type of conspicuous polar thinning is
consistently present. Type NK—2 is similar to type
N K—3 in the uppermost Navesink and Red Bank. N K—3
differs by being smaller than NK—2 and having thinner
walls. Pollen grains from the Paleocene of the Missis-
sippi embayment that are perhaps the same entity as
NK—3 (pl. 2, fig. 5) have been assigned to the extant
Engelhardtia (for example, Elsik, 1968). I consider that
the types NK—l, NK—2, and NK—3 represent a series
transitional from the Normapolles complex (from
Trudopollis or a close relative) to Juglandales.

Type NL (Praebasopollis).—Type NL—l (pl. 2, fig. 6) is
confined to the lower Merchantville but is especially
common in 11218. The bulbous pores are particularly
characteristic of this species. Type NL—2 (pl. 2, fig. 7)
from the Woodbury has less bulbous pores.

Type NM .—See type NF.

Type NN.—Pollen type NN, which occurs from the
Englishtown through the Mount Laurel, is charac-
terized by the Y-shaped polar thickening, thick walls,
and an exopore that has radial baculae on the interior.
Except for the difference in structure of the wall in the
polar area, NN—l (pl. 2, fig. 8) is highly similar to NK—l
(pl. 2, fig. 3). Type NN—2 (pl. 2, fig. 9), which occurs in the
Navesink, Red Bank, and Severn River Monmouth,
lacks radial baculae, has a smaller and rounder exopore,
and has thinner walls than NN—l. As pointed out previ-
ously (Wolfe, 1973), the type represented by NN—2 is
probably assignable to Rhoipteleaceae.

If, as suggested here, types ancestral to J uglandaceae
and Rhoipteleaceae have Normapolles characteristics,
then clearly some true Normapolles must be members of
Juglandales. That is, both NK—1 and NN—l would have
had a common ancestor and that ancestor must be
within J uglandales if this order is a clade rather than a
grade.

Type N0 (Osculapollis).—Type NO—1 (pl. 2, fig. 10)
conforms well to Osculapollis aequalis R. Tschudy. This

 

STRATIGRAPHIC DISTRIBUTION POLLEN, CAMPAN IAN AND MAESTRICHTIAN ROCKS

is a common species from the Englishtown through the
Mount Laurel. A more rotund form of Osculapollis
(NOL2 pl. 2, fig. 11) that has pronouncedly aspidate
pores occures in the Marshalltown through Mount
Laurel. A form (NO—3; pl. 2, fig. 12) similar to NO—2
occurs in the Navesink through Red Bank and in the
Severn River Monmouth; this form differs from N 0—2
by being smaller. NO—4 (pl. 2, fig. 13) is the oldest record
of the genus; this basal Merchantville species is similar
to 0. perspectus R. Tschudy but has a smaller atrium
and tends to have more aspidate exopores.

Type NO—5 (pl. 2, fig. 14; Wenonah) is a polyporate
(5—7 pores) that has the basic pore structure of Os-
culapollis. Conceivably NO—5 is a variant of NO—l, but
NO—l occurs abundantly in several other samples in
which NO—5 is lacking.

Type NP.—This genus has pollen that is decidedly
triangular in polar View with a broadly rounded amb.
The outer and inner wall layers are of approximately
equal thickness; the wall forming the endopore is rag-
ged in the region ofthe pore. Type NP—l (pl. 2, fig. 15) is
thick-walled compared with the other species of the
genus; this type is confined to the Marshalltown. NP—2
(pl. 2, fig. 16), in the Wenonah, has markedly thinner
walls. Forms assigned to NP—2 in the Navesink and
Severn River Monmouth are somewhat smaller than
NP—2 in the Wenonah.

Type N Q .—Pr0nounced sculpturing is unusual for the
Normapolles complex but is known in a few genera.
That NQ (pl. 2, figs. 17—19) is indeed a Normapolles type
is clear from the equatorial thickenings of the outer
wall; the structure of this wall and the relation to the
exopore are similar to NB. Type NQ, however, has a
definite thickening of the exopore on the poleward parts
of the slitlike aperture. The sculpturing in N Q tends to
be irregular; some grains are uniform, others show a
tendency for a gradation in size of the lumina from pole
to equator.

The sculpturing in “Proteacidites” (or as this name is
applied to many grains from the Northern Hemisphere)
is typically thought to be gradational, from smaller lu-
minae at the poles to larger luminae at the equator. In
fact, some of the “Proteacidites” higher in the Coastal
Plain section (see below) have uniform sculpturing and
some have highly reduced sculpturing. The variability
in sculpturing exhibited by these “Proteacidites” is simi-
lar to that exhibited by NQ. Perhaps the primary dis—
tinguishing feature of “Proteacidites” is the formation
by the inner wall of a collar (or annulus) at the pore.
Some specimens of NQ also have a tendency for the
formation of a collar, although the collar does not com-
pletely envelop the pore. The similarities of NQ to both
the Normapolles complex and to “Proteacidites” is here
interpreted to indicate that, as Tschudy (1971) has

SIGNIFICANT POLLEN TYPES

suggested, at least some of the Northern Hemisphere
supposed proteaceous grains are derivatives of the
Normapolles complex and are not closely related to Pro-
teaceae. Martin (1973) has shown that forms from the
Southern Hemisphere that superficially resemble ex-
tant Proteaceae have been invalidly considered to be of
proteaceous affinities.

Type NR (Pseudoccupollis).—A single grain (NR—1;
pl. 2, fig. 20) compares well with Pseudoccupollis ad—
mirabilis R. Tschudy, which is known from the upper
Campanian of the Mississippi embayment. The New
Jersey occurrence (Marshalltown) is in the same
stratigraphic range; in Europe, the genus is known only
from the Santonian and lower Campanian (Goczan and
others, 1967).

Type NS (Longanulipollis).—NS—1 (pl. 2, fig. 21) from
the Englishtown is the sole known representative of
Longanulipollis in North America. This occurrence is
apparently somewhat older than known occurrences of
the genus in Europe (late Campanian-Maestrichtian).
The North American species is, except for its smaller
size, closely similar to the type species of the genus, L.
longianulos (Gocz.) Gocz.

Type NT (Pseudovacuopollis).—Tschudy (1975) re-
cords Pseudovacuopollis involutus (NT—1; pl. 2, fig. 22)
from several samples from the Mississippi embayment
(late early Campanian through Maestrichtian). Thus
far, this species has been encountered in two Atlantic
Coastal Plain samples which came from Marshall-
town—Wenonah transition and the upper part of the
Navesink.

Type N U .——This type is one of the simpler Normapol-
les. The outer and inner walls are of about the same
thickness and are thin. The pores are slightly aspidate
and slit-shaped. Only a trace of sculpturing is present on
the inner wall of the exopore. This species (NU—1; pl. 2,
fig. 23) is known from the Englishtown through the
Marshalltown-Wenonah transition.

Type N V.—This presumed Normapolles type has the
most simplified pore structure of the younger forms of
NK and NN. The Y-shaped polar thickening in NN,
however, has arms oriented towards the pores, whereas
in NV—l (pl. 2, fig. 24; Wenonah and Severn River
Monmouth) the arms are oriented between the pores.

Type PR (“Proteacidites”).—As discussed above, the
pollen from the Atlantic Coastal Plain Cretaceous that
is typically assigned to Proteacidites is probably a de-
rivative of the Normapolles complex. Despite extensive
search in over 40 samples from the Magothy Formation,
no pollen of the type discussed below has been found,
and this type is also missing from the sample from the
basal Merchantville.

PR—l (pl. 2, fig. 25) is characterized by a wide pore
that has a thin collar; this type, the most wide-ranging,

 

15

is found from the Merchantville through the Navesink.
PR—2 (pl. 2, figs. 26, 27) from the Merchantville has a
narrower, more elongate pore that has a conspicuous
collar; also, the wall layers are well differentiated. This
differentiation may be a retention of a feature charac-
teristic of the Normapolles complex. PR—3 (pl. 2, fig. 28)
from the Englishtown has the coarsest sculpturing of
these "Proteacidites.” PR—4 (pl. 2, fig. 29) from the
Wenonah has an elongated collar around the pore; this
type is somewhat similar to PR—2 but has thinner walls
and more distinct sculpturing. PR—5 (pl. 2, fig. 30) from
the Navesink is a small, indistinctly sculptured grain
that has thin walls and an elongated collar around the
pore. PR—6 (pl. 2, fig. 31) from the Englishtown has a
conspicuous collar around the pore but the sculpturing
is most reduced of any of these species. PR-7 (pl. 2, fig.
32) from the Englishtown through the Navesink has a
pronounced collar around the pore and the sculpturing
is fine but distinct.

Type C3A.——Included in this type are grains that are
circular in polar View, have broad and deeply incised
colpi that are not bordered by thickenings, and have
reticulate sculpturing. Type C3A—1 (pl. 3, fig. 1; upper
part of Merchantville through Englishtown) is particu-
larly common in the Woodbury. Type C3A—2 (pl. 3, fig. 2',
basal Merchantville through Englishtown) is larger
and has a finer reticulum than C3A—1. GSA—3 (pl. 3,
fig. 3; uppermost Merchantville and lowermost Wood—
bury) is characterized by the exceptionally coarse re-
ticulum. The Wenonah and Navesink C3A—4 (pl. 3, fig.
4) also has a coarse reticulum, but the ridges are narrow
and the size is smaller than in C3A—3. The ridges of the
reticulum of C3A—5 (pl. 3, fig. 5; upper Woodbury
through Englishtown) are thicker than in C3A—4.

Type C3B.—This type differs from C3A primarily by
having thickened colpal borders although typically the
colpi are somewhat less broad. C3B—1 (pl. 3, fig. 6) is
common in various Woodbury samples. The English-
town C3B—2 (pl. 3, fig. 7) has a finer reticulum and less
deeply incised colpi. C3B—3 (pl. 3, fig. 8) in the Wenonah
and Navesink has a coarse reticulum. With an even
coarser reticulum and a definitely larger size is C3B—4
(pl. 3, fig. 9) in the Marshalltown.

Type C3C.—This type is approximately triangular in
polar View, has colpi that are bordered by thickenings,
and has reticulate sculpturing. Because there is some
indication of pores, this type might prove to be better
classed as a tricolporate (CP3). CSC—l (pl. 3, fig. 11;
Cliffwood and basal Merchantville) has a coarse re-
ticulum that has luminae of irregular shape and size.
The Merchantville material of C3C—1 has somewhat
less deeply incised colpi; in this character it is more
similar to C3C—2 (pl. 3, fig. 12). CBC—2 (Woodbury) has a
finer reticulum that has luminae of approximately reg—

16 STRATIGRAPHIC DISTRIBUTION POLLEN, CAMPANIAN AND MAESTRICHTIAN ROCKS

ular shape and size, and the Englishtown C3C—3 (pl. 3,
fig. 13) has an even finer reticulum. It is possible that
these three species are a phyletic series. The distinc-
tiveness of the Woodbury CBC—4 (pl. 3, fig. 10) with its
coarse and irregular sculpture, large size, and pro-
nouncedly concave sides indicates little, if any, close
relationship to the other species of C3C.

Type CP3A.—This type is characterized by its circu-
lar shape in polar View, colpi that have thickened bor-
ders, and reticulate sculpturing. CP3A—1 (pl. 3, fig. 16)
and CP3A—2 (pl. 3, fig. 14) have overlapping ranges
(upper part of Merchantville and Woodbury) but appear
to be closely similar. CP3A—2 is smaller and has less
deeply incised colpi than CP3A—1. CP3A—3 (pl. 3, fig. 17;
Navesink) is similar to CP3A—1 in size and degree of
incision of the colpi but has a much finer reticulum.

Type CP3B.—This type is similar to CP3A but is
triangular rather than circular in polar View; the outer
and inner walls are of equal thickness. CP3B—1 (pl. 3,
fig. 15; Cliffwood beds and basal Merchantville) has
colpi incised about halfway to the poles and a fine re-
ticulum. CP3B—2 (pl. 3, fig. 18; upper part of Mer-
chantville) has a coarser reticulum and thicker margoes
than CP3B—1. A common form in several Woodbury
samples is CP3B—3 (pl. 3, fig. 19), which has an excep-
tionally coarse reticulum, pronounced margoes, and
short colpi. CP3B—4 (pl. 3, fig. 20; upper part of Wood-
bury) has sculpturing similar to CP3B—2 (except that
the reticulum is thicker as in CP3B—5), but the margoes
are similar in thickness to CP3B—3. CP3B—5 (pl. 3,
fig. 21; Englishtown) has sculpturing and margoes simi-
lar to CP3B—2, but the colpi are short. If these various
species represent a phyletic series, it is apparent that
the trends toward coarse sculpturing and thickened
margoes were reversed in late Woodbury times, in con-
trast to the consistent trends towards shortening of the
colpi and increase in thickness of the reticulum.

Whereas the margoes in CP3B—1 through 5 tend to
thin poleward, in forms CP3B—6, 7, and 8, they tend to
be ofuniform thickness. CP3B—6 (pl. 4, fig. 1; Woodbury
and Merchantville) is similar to CP3B—2 in sculpturing,
but the wall of the grain curves around the corners to
make a slitlike colpus. CP3B—7 (pl. 4, fig. 2; English-
town) is smaller than CP3B—6 and has the pore more
deeply inset from the corners ofthe grain. CP3B—8 (pl. 4,
fig. 3; Wenonah) is smaller than these two forms and has
a finer reticulum.

Type CP3C.—This type is similar to CPSB except that
the inner wall is thicker than the outer wall. CP3C—1
(pl. 4, fig. 4; Woodbury) is rare but is so distinctive that it
would be readily recognizable and perhaps be an excel-
lent marker. In wall structure and sculpturing, CP3C—1
is similar and may be ancestral to CP3C—2 (pl. 4, fig. 5;
Englishtown). CP3C—2 is smaller and the pores are

 

protruding.

Type CP3D.—Type CP3D is recognized on the basis
of the straight channeling of the inner wall and the
baculate sculpturing. Tertiary material of this type has
been referred to Holkopollenites Fairchild (in Stover
and others, 1966), which has been recorded by several
workers from the Paleocene and Eocene of the Missis-
sippi embayment. The oldest record of this type is small
grains from the Cliffwood beds and Merchantville; this
species (CP3D—1; pl. 4, figs. 6, 7) varies, as do younger
species of the genus, by having concave to convex sides.
CP3D—2 (pl. 4, figs. 8, 9; Woodbury and Englishtown) is
considerably larger than CP3D—1. CP3D—3 (pl. 4, fig. 10;
Marshalltown through Red Bank) has more deeply in-
cised colpi than CP3D—2; there is also a tendency for
the sides ofthe grains to be more convex in CP3D—3 and
more concave in CP3D—2. H. chemardensis Fairch. has
colpi more deeply incised than in CP3D—3.

Type CP3E .—In this type, the inner wall is channeled
by anastomosing rather than straight grooves, and the
sculpturing is decidedly finer than in Holkopollenites.
CP3E—1 (pl. 4, fig. 11) occurs in the upper part of the
Merchantville, Woodbury, and Englishtown; this type
is questionably known in the Mount Laurel. The one
grain of this type from the Mount Laurel sample is
smaller than any of the Woodbury or Englishtown
specimens, but more Mount Laurel specimens will be
needed to determine whether this size difference is
consistent.

Type CP3F.—This type is pronouncedly brevicolpate,
and is triangular in polar view; the apertures are lo-
cated at the ambs. CP3F—1 (pl. 4, fig. 12; Merchantville
through Englishtown) is very indistinctly sculptured
relative to the more distinct sculpturing 0f CP3F—2
(pl. 4, fig. 13; Mount Laurel through Red Bank).

Type CP3G.—CP3G—1 (pl. 4, fig. 14; upper part ofthe
N avesink, Red Bank, and Severn River Monmouth) is
characterized by exceptionally thick walls. The
sculpturing is inconspicuously punctate.

Miscellaneous pollen types.—MPA—1 (pl. 4, fig. 15) is
tricolporate, the colpi have thickened borders, and the
apertures are located between the corners. This pollen
type from the Merchantville is perhaps the forerunner
of the bombacaceous type, which is present in the N ave-
sink. Type MPB—l (pl. 4, fig. 16) is similar in sculpturing
and size to pollen of the extant bombacaceous Cavanel—
lisia. MPC—l (pl. 4, fig. 17) from the Severn River Mon-
mouth is probably referable to Bombacidites on the
basis of having larger meshes at the poles than at the
equator (Srivastava, 1972).

MPD—l (pl. 4, fig. 18) is a characteristic syncolpate
known only from the Severn River Monmouth and the
Red Bank. Types MPIL2 (pl. 4, fig. 19; Wenonah and
Severn River Monmouth) and MPD—3 (pl. 4, fig. 20;

REFERENCES CITED

lower part of the Navesink) are less conspicuously
sculptured than MPD—l. The sculpturing in MPD—3 is
greatly reduced near the colpal borders compared with
MPD—2. Fragments of the syncolpate Trisectoris occur
throughout the section, and this genus is known in the
Magothy (Wolfe and Pakiser, 1972). Other syncolpate
types are rare; none are known in more than one sam-
ple. In general, more different types of syncolpates are
known in the upper Campanian and Maestrichtian (at
least seven types) than in the lower Campanian (two
types).

Polyporates are unknown in the lower Campanian
part of the section, whereas at least 10 types are known
from samples in the Marshalltown through Red Bank
interval. Of these types, only four occur in more than
one sample. MPE—l (pl. 4, figs. 21, 22), which is a
polyporate grain that has weak sculpturing, is known
from the Severn River Monmouth; this type is perhaps
of centrospermous affinity. Polyporate type MPF—l
(pl. 4, figs. 23, 24; Wenonah through Red Bank) has
fewer pores than MPE—l, and the membranes covering
the pores are flecked; similar pore membranes are found
in extant families that are not closely related (for exam—
ple, Hamamelidaceae and Pistaciaceae) and thus offer
no certain clue of affinities. MPG—1 (pl. 4, fig. 25;
Navesink and Severn River Monmouth) is a four—pored
grain that has verrucate sculpturing; this type is almost
certainly of ulmaceous affinity.

Types MPH—1 (pl. 4, fig. 26; Marshalltown and
Wenonah) and MPH—2 (pl. 4, fig. 27; lower part of the
Navesink and Severn River Monmouth) are polycolpo-
rates; MPH—2 differs by having a thinner wall and less
conspicuous sculpturing.

MPl—l (pl. 4, fig. 28) represents Aquilapollenites. I
have found this in only one sample (from the Wenonah),
whereas Evitt (oral commun., 1973) records the genus
from the Marshalltown and the Red Bank.

FOSSIL LOCALITIES

Lat 39°28’42” N., long 75°59’36” W. Merchantville Formation.
Collector J. P. Owens.

Lat 39°23’55” N., long 76°02’26” W. Merchantville Formation,
lower part. Collector J. P. Owens.

Lat 39°22’ 15” N., long 76°05’30” W. Merchantville Formation,
about 10 ft above beach. Collector J. P. Owens.

Same locality as 11173, Merchantville Formation, about 13 ft
above beach. Collector J. P. Owens.

Lat 39°21’10” N., long 76°03’58" W. Englishtown Formation,
about middle. Collector J. P. Owens.

Lat 39°02’03” N., long 76°33’20” W. Monmouth Formation on
southwest side Severn River. A, near base; B, +8 ft; C, +16
ft; D, +20 ft; E, +24 ft. Samples collected about 4 ft apart.
Collector J. A. Wolfe.

Lat 39°02’03” N., long 76°33’20” W. Monmouth Formation, on
northeast side Severn River. Samples collected about 3 ft
apart. Collector J. A. Wolfe.

11156.

11172.

11173.

11174.

11176.

11210.

11212.

 

17

11213. Lat 39°03’40” N., long 76°33' 17” W. uppermost Marshalltown
Formation or lowermost Wenonah Formation. Samples col-
lected about 3—4 ft apart. Collector J. A. Wolfe.

Lat 40°26’49" N., long 74°12’39” W. Cliffwood beds ofMagothy
Formation. A, at mollusk horizon; B, about +15 ft; remain-
der samples about 2 to 3 ft apart, and H at top. Collector J. A.
Wolfe.

Same latitude and longitude as 11217. Merchantville Forma-
tion, basal part above reworked bed. Collector J. A. Wolfe.

Lat 40°26’20” N., long 74°14’47” W. Merchantville Formation,
middle and upper part. Samples collected about 3 ft apart.
Collector J. A. Wolfe.

Lat 40°22’19” N., long 74°18’30” W. Woodbury Clay, upper
part. Samples collected about 7 ft apart. Collector J. A.
Wolfe.

Lat 40°24’50” N., long 74°01’35” W. Navesink Formation,
lower part. A,just above contact with Mount Laurel Sand; B,
+3 ft. Collector J. A. Wolfe.

Lat 40°24’49” N., long 74°01’21” W. Navesink Formation,
upper part. Samples collected about 3 ft apart. Collector J. A.
Wolfe.

Same latitude and longitude as 11223. Red Bank Sand, basal
part. Collector J. A. Wolfe.

Lat 40°08'16" N., long 74°33’18” W. Wenonah Formation,
basal part. Samples collected about 2 ft apart. CollectorJ. A.
Wolfe.

Lat 40°07’57" N., long 74°36’27” W. Englishtown Formation,
middle part. Samples collected about 3 ft apart. Collector
J. A. Wolfe.

Lat 40°07’35" N., long 74°42’31” W. Woodbury Clay, lower
part. Samples collected about 4—5 ft apart. Collector J. A.
Wolfe.

Lat 40°07’40” N., long 74°43’47” W. Magothy Formation,
upper part. Samples about 2 ft apart. Collector J. A. Wolfe.

Lat 40°07’19” N., long 74°47’39” W. Magothy Formation,
lower part. Collector J. A. Wolfe.

Lat 39°32’37” N., long 75°42’23” W. Marshalltown Formation,
lower part. Collector J. A. Wolfe.

1 1231. Lat 39°32’24” N., long 75°44'35” W. Merchantville Formation,

upper part. Samples collected about 2 ft apart. Collector J. A.
Wolfe.

11232. Lat 39°32’22” N., long 75°44’35” W. Magothy Formation. A, at
base above contact with Potomac Group; B, +10—12 ft; C,
+15 ft; D, +25 ft, at top. Collector J. A. Wolfe.

Lat 39°33’ 12” N., long 75°38’ 14” W. Mount Laurel Sand, lower
part (same as USGS Mesozoic loc. 29585 of Owens and
others, 1970, p. 48, "Gryphaea” bed). Collector J. A. Wolfe.

1 1234. Lat 39°33’12" N., long 75°38’ 14" W. Marshalltown Formation,

near top. Collector J. A. Wolfe.

11351. Excavation along south bank of Mantua Creek, northeast of

road and bridge of Rt. 45 at Mantua, Gloucester County,
N.J. Same as USGS Mesozoic loc. 30252. Marshalltown
Formation, middle part. Collector N. F. Sohl.

11217.

11218.

11219.

11221.

11222.

11223.

11224.

11225.

11226.

11227.

11228.
11229.

11230

11233.

REFERENCES CITED

Brenner, G. J., 1963, The spores and pollen of the Potomac Group of
Maryland: Maryland Dept. Geology, Mines, and Water Resources
Bull., v. 27, 215 p.

Clark, W. B., 1916, The Upper Cretaceous deposits of Maryland:
Maryland Geol. Survey, Upper Cretaceous [Volume], p. 23—110.

Doyle, J. A., 1969, Cretaceous angiosperm pollen of the Atlantic
Coastal Plain and its evolutionary significance: Jour. Arnold
Arboretum, v. 50, p. 1—35.

18 STRATIGRAPHIC DISTRIBUTION POLLEN, CAMPANIAN AND MAESTRICHTIAN ROCKS

Elsik, W. C., 1968, Palynology ofa Paleocene Rockdale Lignite, Milam
County, Texas: Pollen et Spores, v. 10, p. 599—664.

Goczan, Ferenc, Groot, J. J., Krutzsch, Wilfred, and Pacltova, Blanka,
1967, Die Gattungen des “Stemma Normapolles Pflug 1953b”
(Angiospermae): Palaontologische Abhand., Abt. B,
Palaobotanik, v. 2, no. 3, p. 429—539, 19 pls.

Gray, T. C., and Groot, J. J., 1966, Pollen and spores from the marine
Upper Cretaceous formations of Delaware and New Jersey:
Palaeontographica, Abt. B, v. 117, p. 114—134, pls. 42—43.

Hughes, N. F., and Moody—Stuart, J. C., 1967, Palynological facies and
correlation in the English Wealden: Review Palaeobotany and
Palynology, v. 1, p. 259—268.

Martin, A. R. H., 1973, Reappraisal ofsome palynomorphs ofsupposed
proteaceous affinity. I. The genus Beaupreadites Cookson ex
Couper and the species Proteacidites hakeoides Couper: Geol. Soc.
Australia Spec. Pub. 4, p. 73—78.

Minard, J. P., 1974, Geology of the Betterton Quadrangle, Kent
County, Maryland, and a discussion of the regional stratigraphy:
U.S. Geol. Survey Prof. Paper 816, 27 p.

Owens, J. P., Minard, J. P., Sohl, N. F., and Mello, J. F., 1970,
Stratigraphy of the outcropping post-Magothy formations in
southern New Jersey and northern Delmarva Peninsula, Dela-
ware and Maryland: U.S. Geol. Survey Prof. Paper 674, 60 p.

Owens, J. P., and Sohl, N. F., 1973, Glauconites from the New
Jersey-Maryland Coastal Plain; their K/Ar ages and application
in stratigraphic studies: Geol. Soc. America Bull., v. 84, p. 2811—
2838.

 

Sohl, N. F., 1964a, Neogastropoda, Opisthobranchia, and Basom-
matophora from the Ripley, Owl Creek, and Prairie BluffForma-
tions: U.S. Geol. Survey Prof. Paper 331—B, p. B153—B344.

1964b, Gastropods from the Coffee Sand (Upper Cretaceous) of
Mississippi: U.S. Geol. Survey Prof. Paper 331—C, p. C345—C394.

Srivastava, S. K., 1972, Some spores and pollen from the Paleocene
Oak Hill Member of the Naheola Formation, Alabama (U.S.A.):
Review Palaeobotany and Palynology, V. 14, p. 217—285.

Stover, L. E., Elsik, W. C., and Fairchild, W. W., 1966, New genera and
species of early Tertiary palynomorphs from Gulf Coast: Kansas
Univ. Paleont. Contr., Paper 5, 11 p., 5 pls.

Tschudy, B. D., 1971, Two new fossil pollen genera from upper Cam-
panian (Cretaceous) rocks of Montana: U.S. Geol. Survey Prof.
Paper 750—B, p. B53—B61.

Tschudy, R. H., 1973, Complexiopollis pollen lineage in Mississippi
Embayment rocks: U.S. Geol. Survey Prof. Paper 743—C, p. C1—
C14, 9 pls.

1975, Normapolles pollen from the Mississippi Embayment:
U.S. Geol. Survey Prof. Paper 865, 40 p., 20 pls.

Wolfe, J. A., 1971, Tertiary climatic fluctuations and methods of
analysis of Tertiary floras: Palaeogeography, Palaeoclimatology,
Palaeoecology, V. 9, no. 1, p. 27—57.

1973, Fossil forms ofAmentiferae: Brittonia, V. 25, p. 334—355.

Wolfe, J. A., and Pakiser, H. M., 1971, Stratigraphic interpretations of
some Cretaceous microfossil floras of the Middle Atlantic States:
U.S. Geol. Survey Prof. Paper 750—B, p. B35—B47.

 

 

 

 

 

PLATES 1—4

[Contact photographs of the plates in this report are available at cost, from the US. Geological
Survey Library, Federal Center, Denver, Colo. 80225]

 

 

PLATE 1

Campanian and Maestrichtian pollen. All figures X 1,000.

FIGURE 1.
2.

9051.07???“

11,12.
13.

14.
15.
16.
17.
18.
19.
20.

21.

22.

23, 24.

25.

26.

27.

28.

29, 30.
31, 32.
33, 34.

35.

NA—l Englishtown Formation, loc. 11226—A, slide 3, 1034 X 14.0
NA—2. Englishtown Formation, loc. 11226—C, slide 1, 90.0 X 3.5.
NA—3. Wenonah Formation, loc. 11213—C, slide 3, 104.6 X 19.7.
NA—4. Monmouth Formation, loc. 11210—E, slide 2, 102.5 X 22.4.
NA—5. Monmouth Formation, loc. 11212—H, slide 1, 94.3 X 4.1.
NA—6. Merchantville Formation, 100. 11218, slide 3, 113.2 X 3.1.
NA—7. Englishtown Formation, loc. 11226—C, slide 2, 86.1 X 2.9.
NA—8. Red Bank Sand, 100. 11224, slide 3, 83.3 X 17.9.
NB—l. Woodbury Clay, loc. 11227—C, slide 2, 88.2 X 4.7.
NB—2. Merchantville Formation, loc. 11218, slide 3, 90.5 X 5.0.
NB—3. Wenonah Formation, loc. 11225—C, slide 3, 100.0 X 7.5.
NC—l. Woodbury Clay, loc. 11221~A, slide 2, 89.0 X 5.9.
NC—2. Merchantville Formation, loc. 11219—E, slide 2, 100.2 X 20.6.
NC—3. Marshalltown Formation, loc. 11351, slide 2, 83.1 X 16.4.
ND—l. Merchantville Formation, loc. 11218, slide 3, 110.0 x 15.6.
ND—2. Marshalltown Formation, 10c. 11230, slide 3, 103.8 X 15.6.
ND~3. Englishtown Formation, loc. 11176, slide 2, 103.2 X 13.9.
NE—1. Merchantville Formation, 10c. 11219—G, slide 2, 95.3 X 10.0.
NE—2. Englishtown Formation, 10c. 11226—C, slide 3, 80.8 X 5.2.
NE—3. Wenonah Formation, loc. 11225—C, slide 3, 102.6 X 6.2.
NE—4. Merchantville Formation, 10c. 11219—B, slide 1, 98.4 X 15.0.
NF—l. 23, Merchantville Formation, 10c. 11219—B, slide 1, 90.6 X 13.9.
24, Merchantville Formation, loc. 11219—E, slide 2, 83.9 X 13.3.
NF—2. Woodbury Clay, 10c. 11227—B, slide 2, 89.9 X 18.0.
NM—l. Englishtown Formation, 100. 11176, slide 2, 103.8 X 12.6.
NF~3. Mount Laurel Sand, 10c. 11233, slide 3, 78.9 x 15.5.
NF~4. Englishtown Formation, 10c. 11176, slide 2, 90.3 X 3.0.
NG—l. Navesink Formation, 10c. 11223—A, slide 1, 91.7 X 5.0.
NI—1. Merchantville Formation, loc. 11218, slide 3, 96.1 X 5.6.
NI—2. Englishtown Formation, loc. 11226—A, slide 3, 112.7 X 4.5.
NH—1. Monmouth Formation, loc. 11212—E, slide 2, 96.1 X 3.3.

PROFESSIONAL PAPER 977 PLATE 1

GEOLOGICAL SURVEY

 

CAMPANIAN AND MAESTRICHTIAN POLLEN , NA—l TO NH—l

PLATE 2

Campanian and Maestrichtian pollen. All figures X 1,000.

FIGURE 1.

20.
21.
22.
23.
24.

25.
26, 27.
28.
29.
30.
31.
32.

NJ—l. Woodbury Clay, 10c. 11227—D, slide 2, 105.3 X 20.8.
NJ~2. Mount Laurel Sand, 100. 11233, slide 4, 108.1 X 19.4.
NK—l. Wenonah Formation, loc. 11225—B, slide 3, 107.4 X 2.8.
NK—2. Monmouth Formation, 10c. 11210—E, slide 2, 99.5 X 4.6.
NK—3. Red Bank Sand, 100. 11224, slide 3, 94.9 X 11.4.
NL—1. Merchantville Formation, loc. 11218, slide 2, 82.4 X 10.0.
NL—2. Woodbury Clay, loc. 11227—C, slide 1, 88.5 X 4.1.
NN—1. Wenonah Formation, loc. 11213—A, slide 3, 85.1 X 5.0.
NN—2. Monmouth Formation, loc. 11210—A, slide 1, 106.9 x 13.7.
NO~1. Englishtown Formation, loc. 11226—C, slide 1, 1062 X 21.5.
NO—2. Wenonah Formation, loc. 11225—C, slide 3, 92.8 X 8.6.
NO—3. Monmouth Formation, 10c. 11212—H, slide 2, 88.8 X 5.9.
NO—4. Merchantville Formation, loc. 11218, slide 3, 111.7 X 4.3.
NO-5. Wenonah Formation, 10c. 11225—B, slide 3, 81.9 X 17.6.
NP—1. Marshalltown Formation, loc. 11234, slide 2, 1037 X 13.9.
NP—2. Monmouth Formation, 10c. 11212—E, slide 2, 101.6 X 12.9.
NQ—l. 17, Cliffwood beds, loc. 11217—A, slide 2, 102.5 X 2.9.

18, Cliffwood beds, loc. 11217—B, slide 2, 81.7 X 5.2.

19, Cliffwood beds, 10c. 11217—D, slide 2, 99.4 X 4.8.
NR—l. Marshalltown Formation, loc. 11234, slide 4, 96.5 X 10.7.
NS—l. Englishtown Formation, loc. 11226—C, slide 3, 98.8 X 13.9.
NT—1. Navesink Formation, 10c. 11223~A, slide 3, 101.8 X 6.6.
NU~1. Englishtown Formation, loc. 11226—C, slide 3, 94.9 X 2.7.
NV—l. Monmouth Formation, loc. 11212—H, slide 2, 83.5 X 9.9.
PR—l. Woodbury Clay, loc. 11221—A, slide 1, 103.8 X 12.2.
PR2. Merchantville Formation, 10c. 11219—G, slide 2, 90.7 X 12.9.
PR—3. Englishtown Formation, 10c. 11176, slide 2, 98.0 X 9.1.
PR—4. Wenonah Formation, loc. 11225—C, slide 2, 82.0 X 6.8.
PR—5. Navesink Formation, loc. 11222—B, slide 2, 106.3 X 16.5.
PR—6. Englishtown Formation, loc. 11226—A, slide 1, 101.2 X 17.2.
PR—7. Englishtown Formation, loc. 11226—C, slide 3, 86.1 X 8.4.

PROFESSIONAL PAPER 977 PLATE 2

GEOLOGICAL SURVEY

 

 

CAMPANIAN AND MAESTRICHTIAN POLLEN, NJ—l TO PR—7

PLATE 3

Campanian and Maestrichtian pollen. All figures X 1,000.

FIGURE 1.

C3A—1. Merchantville Formation, 100. 11172, slide 1, 104.9 X 22.4.
C3A—2. Englishtown Formation, loc. 11226—A, slide 2, 84.4 X 8.0.
C3A—3. Woodbury Clay, loc. 11227—C, slide 1, 86.0 X 14.8.

GSA—4. Wenonah Formation, loc. 11225—B, slide 3, 87.8 X 15.2.
C3A—5. Woodbury Clay, 10c. 11221—A, slide 2, 99.3 X 3.3.

C3B—1. Woodbury Clay, loc. 11227~C, slide 1, 100.1 x 3.0.

C3B—2. Englishtown Formation, 10c. 11226—A, slide 1, 83.6 X 7.3.
C3B—3. Wenonah Formation, 10c. 11213—B, slide 2, 81.4 X 10.6.
C3B—4. Marshalltown Formation, 100. 11230, slide 3, 105.7 X 7.5.
C3C—4. Woodbury Clay, loc. 11227-C, slide 1, 104.0 X 6.0.

C3C—1. ClifTwood beds of Magothy Formation, 10c. 11217—C, slide 2, 106.6 X 3.7.
C30—2. Woodbury Clay, 10c. 11221—A, slide 1, 101.4 X 7.9.

CBC—3. Englishtown Formation, loc. 11226—A, slide 2, 82.6 X 11.1.
CP3A—2. Woodbury Clay, 10c. 11227—A, slide 1, 108.7 X 13.3.
CP3B—1. Cliffwood beds of Magothy Formation, loc. 11217—C, slide 2, 88.7 X 14.2.
CP3A—1. Merchantville Formation, loc. 11219—E, slide 2, 107.7 x 3.7.
CP3A—3. Navesink Formation, loc. 11222—B, slide 2, 87.3 X 17.2.
CP3B—2. Merchantville Formation, loc. 11219—F, slide 2, 101.3 X 8.1.
CP3B—3. Woodbury Clay, loc. 11227—D, slide 2, 99.2 X 8.5.

CP3B—4. Woodbury Clay, loc. 11221—B, slide 3, 82.3 X 13.8.

CP3K5. Englishtown Formation, 10c. 11226—C, slide 3, 99.9 X 21.2.

PROFESSIONAL PAPER 977 PLATE 3

GEOLOGICAL SURVEY

 

CAMPANIAN AND MAESTRICHTIAN POLLEN , C3A—1 TO CP3B—5

PLATE 4

Campanian and Maestrichtian pollen. All figures X 1,000.

FIGURE 1.

10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21, 22.
23, 24.
25.
26.
27.
28.

CP3B—6.
CP3B—7.
CP3B—8.
CP3C—1.
CP3C—2.
CP3D—1.

CP3D—2.

CP3D—3.
CP3E—1.
CP3F—1.
CP3F—2.

CP3G—1
MFA—1.
MPB—l.
MPC—l.
MPD—l.
MPD—2.
MPD—3.
MPE—l.
MPF—l.
MPG—1.
MPH—1.
MPH—2.

Merchantville Formation, loc. 11172, slide 1, 90.0 X 14.0.

Englishtown Formation, loc. 11226—A, slide 2, 94.8 X 3.6.

Wenonah Formation, loc. 11225—C, slide 3, 85.6 X 5.3.

Woodbury Clay, loc. 11227«A, slide 2, 93.3 X 8.5.

Englishtown Formation, loc. 11226—C, slide 3, 105.7 X 11.8.

6, Cliffwood beds of Magothy Formation, loc. 11217—F, slide 2, 97.1 X 8.2.
7, Merchantville Formation, loc. 11173, slide 1, 89.4 X 5.7.

8, Merchantville Formation (Woodbury age), 100. 11231—D, slide 1, 96.5 X 17.9.
9, Englishtown Formation, 100. 11176, slide 2, 102.1 x 8.0.

Wenonah Formation, loc. 11225—B, slide 3, 106.9 X 5.3.

Woodbury Clay, loc. 11231—D, slide 1, 94.9 X 17.1.

Englishtown Formation, loc. 11226~A, slide 3, 106.5 x 5.3.

Navesink Formation, loc. 11223—B, slide 3, 106.5 X 17.8.

. Monmouth Formation, loc. 11212—A, slide 2, 102.3 X 4.5.

Merchantville Formation, loc. 11219—B, slide 1, 101.1 X 19.6.
Navesink Formation, loc. 11223—B, slide 3, 113.9 X 22.7.
Monmouth Formation, loc. 11212G, slide 2, 83.0 X 2.6.
Monmouth Formation, loc. 11210—B, slide 2, 101.2 X 6.9.
Wenonah Formation, loc. 11225—C, slide 2, 86.4 X 16.4.
Navesink Formation, loc. 11223—B, slide 4, 106.3 X 1.8.
Monmouth Formation, 10c. 11212—E, slide 2, 90.0 X 7.7.
Wenonah Formation, loc. 11213-B, slide 3, 100.4 X 16.2.
Monmouth Formation, loc. 11212~E, slide 1, 109.3 X 16.8.
Wenonah Formation, loc. 11213—A, slide 2, 83.4 X 9.4.
Monmouth Formation, loc. 11210—B, slide 1, 108.4 X 10.6.

MPI—l. Wenonah Formation, loc. 11213—B, slide 3, 1116 X 16.8.

PROFESSIONAL PAPER 977 PLATE 4

GEOLOGICAL SURVEY

 

CAMPANIAN AND MAESTRICHTIAN POLLEN, CP3B—6 TO MPI—l