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STATE OF ILLINOIS

STATE GEOLOGICAL SURVEY

FRANK W. DeWOLF, Director

BULLETIN No. 31

OIL INVESTIGATIONS IN ILLINOIS IN 1914

Area south of the Colmar oil field
By William C. Morse and Fred H. Kay

The Colmar oil field—a restudy
By William C. Morse and Fred H. Kay

The Allendale oil field
By John L. Rich

Anticlinal structure in Randolph County
By Stuart Weller

Oil and £as in Gillespie and Mt. Olive quadrangles

By Wallace Lee

Work in cooperation with
U. S. Geological Survey

ILLINOIS STATE GEOLOGICAL SURVEY
UNIVERSITY OF ILLINOIS
URBANA
1915

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STATE GEOLOGICAL COMMISSION

Edward F. Dunne, Chairman
Governor of Illinois

Thomas C. Chamberlin, Vice-Chairman

Edmund J. James, Secretary
President of the University of Illinois

Frank W. DeWolf, Director
Fred H. Kay, Asst. State Geologist

LETTER OF TRANSMITTAL

State Geological Survey

University of Illinois, April 26, 1915

Governor E. F. Dunne, Chairman, and Members of the Geological

Commission.

I submit herewith a report on oil investigations during 1914 and recom¬
mend that it be published as Bulletin No. 31.

The first two papers, by W. C. Morse and Fred H. Kay, relate to the
new oil fields of western Illinois which were first surveyed in 1912 and
proved productive near Colmar in 1914. A restudy of the original area is
presented, and also a detailed report on new territory south of the Colmar
field, which was surveyed last season.

Another paper prepared for the bulletin by J. L. Rich relates to the
comparatively new Allendale field in Wabash County.

The fourth paper, by Stuart Weller, describes a prominent anticlinal
fold in Randolph County, which is believed to merit drilling in search of
oil or gas.

The last paper by Wallace Lee of the U. S. Geological Survey, in
cooperation with this office, outlines the possibilities of oil and gas accumu¬
lation in the Gillespie and Mt. Olive quadrangles of Macoupin, Mont¬
gomery, and Bond counties. The producing fields near Carlinville and
Litchfield are described in detail.

Oil production in Illinois continues to be second only to that of coal.
The old fields are nevertheless on the decline, and new areas must be dis¬
covered if important production is to continue. The Geological Survey is
devoting much attention to the problem.

Very respectfully,

Frank W. DeWolf, Director

CONTENT S

Page

THE AREA SOUTH OF THE COLMAR OIL FIELD. 8

THE COLMAR OIL FIELD. 37

THE ALLENDALE OIL FIELD. 57

ANTICLINAL STRUCTURE IN RANDOLPH COUNTY. 69

OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES. 71

( 6 )

Scolti

40 90

• OO

Fig. 1. Map showing area covered in first two reports.

THE AREA SOUTH OF THE COLMAR OIL FIELD

I3y William C. Morse and Fred H. Kay
(Field work by William C. Morse and John L. Rich)

(In cooperation with the U. S. Geological Survey)

OUTLINE

Page

Introduction . 10

Acknowledgments . 10

Personnel of the party. 11

Method of field work. 11

Key rocks. 11

Stratigraphy. 12

General statement. 12

Unconsolidated rocks. 12

Alluvium. 12

Loess . 13

Drift .•. 13

Consolidated rocks. 14

General description. 14

Carbondale formation. 17

Pottsville formation. 18

St. Louis limestone. 19

Salem formation. 21

Warsaw formation. 21

Keokuk limestone. 22

Burlington limestone. 22

Kinderhook and Upper Devonian shale. 23

Devonian limestone. 23

Niagaran dolomite. 23

Ordovician formations. 23

Position of Hoing sand in the section. 24

Structure . 24

General statement. 24

Relation of folds in oil-bearing stratum to accumulation. 26

Detailed structure. 29

General statement.•. 29

Folds shown by coal No. 2 and St. Louis limestone. 30

Recommendations . 31

Localities already tested. 34

( 8 )

ILLUSTRATIONS

PLATE PAGE

I Map of parts of Schuyler, Brown, Adams, and Hancock counties. 28

FIGURE

1. Map showing area covered in first two reports. 7

2. Loess in the west bluff of Illinois River below Frederick. 12

3. Loess hills near Frederick. 13

4. Graphic sections (1) from measurements on outcrops; (2) log of Hoing

No. 1 well. 16

5. Colchester (No. 2) coal and overlying black shales west of Rushville. 17

6. Unconformity at base of Pottsville, Harrison Branch. 18

7. St. Louis limestone east of Birmingham. 19

8. Caves in St. Louis limestone filled by Pottsville sands. 20

9. Erosion planes in St. Louis limestone, Harrison Branch. 20

10. Keokuk limestone near Plymouth. 22

11. Diagram showing significance of unconformities. 25

12. Diagrams showing conditions governing oil accumulation.

A. In oil sands saturated with salt water . 27

B. In oil sands partly saturated . 27

C. In sands containing no salt water . 27

TABLES

PAGE

1. Drill holes in area south of Colmar field. 35

( 9 )

INTRODUCTION

Oil was discovered on the J. Hoing farm on April 30, 1914 in what is
now known as the Colmar Oil Field, an area suggested as favorable for
the accumluation of oil or gas in a joint report of the United States Geologi¬
cal Survey and the State Geological Survey by Henry Hinds 1 . To date
more than 130 producing wells have been completed and the output is now
approximately 650 barrels per day.

In the hope of locating other areas in which the geological structure is
favorable for the accumulation of oil or gas the work during the past season
has been pushed on to the south. The new territory now completed (see
figure 1) includes the whole of Schuyler County except the small point
east of Sugar Creek; the adjoining part of Brown included roughly within
lines running from Ripley to Mt. Sterling and from Mt. Sterling to Damon ;
and the adjacent belt on the west, one to three miles broad, in Adams and
Hancock counties.

Acknowledgments

An introduction to the geology of this part of the State was given by
Dr. Stuart Weller, accompanied by Mr. F. M. Van Tuyl of the Iowa Survey,
who met Messrs. Morse and Rich at Keokuk, Iowa, visited the type localities
of the Keokuk and Warsaw formations and made with them a three-day
reconnaissance automobile trip through McDonough, Schuyler, and Brown
counties. Acknowledgment must also be made at the outset to Dr. John
L. Rich, who was a collaborator in the study of nearly the whole of Schuyler
County, and who assumed the extra duty of directing the instrument men.
He would have been joint author had he not been called east before the
areas in Brown, Adams, and Hancock counties and the Colmar field were
studied. Free use has been made of the report of Mr. Henry Hinds of the
U. S. Geological Survey, which was published under a co-operative agree¬
ment by the State Survey. Mr. Raymond S. Blatchley located and deter¬
mined the elevations of about 15 producing wells and a similar number of
dry ones in the Colmar field. He also secured a large number of well
records which the senior author was unable to obtain because of lack of time.

A friendly cooperation was manifest on every hand, both by the owners
of the farms and the oil men. Free camp sites and automobile storage,
one or both, were furnished by Mr. W. C. Blackburn of Brooklyn, Mr. Roy
Moore of Rushville, Mr. Hare of Mt. Sterling, and Mr. Henry Pearson

minds, Henry, Oil and gas in the Colchester and Macomb quadrangles: Ill. State Geol.
Survey, Extract Bull. 23, pp. 11-13, 1914.

( 10 )

THE AREA SOUTH OF THE COLMAR OIL FIELD

and son of Augusta. Well records and other information were freely given
by Messrs. Page and Crew of the Ohio Oil Company, Mr. Glass of Snowden
Brothers and Company, Mr. B. A. Kinney of the Lamoine Oil and Gas
Company, Mr. Frank Lawler, representing Messrs. J. B. and W. H. Hazlett,
Mr. P. B. Lamberton of Lamberton and Baker, Mr. Lewis of J. E. Urschel
and Company, and others.

Personnel of the Party

The party, in addition to Messrs. Rich and Morse, included at various
times: David E. Day, John D. Mattison, J. Philip Pepper, H. S. Eisu, Victor
Wood, Paul F. Morse, J. Hazlette Bell, Harold R. Moore, James A. Lee,
Jas. H. Pierson, L. W. Robison, Jas. Barger, Ray Post, Harry A. Almond,
and J. W. Hemphill.

Method of Field Work

Since the beds in the area lie approximately parallel to one another, the
position and altitude of any underlying stratum such as an oil sand, can be
learned by determining the position of any persistent recognizable bed ex¬
posed at the surface.

The position of the oil sand bears a direct relation to the accumulation
of petroleum, as explained under “Relation of geologic structure to oil and
gas accumulation;" and in the region under consideration, instrumental
levels were run to outcrops of certain beds that could be somewhat easily
recognized by the geologists. An attempt was made to find outcrops not
more than one mile distant from one another. Field work began July 1
and continued to November 1. It was conducted from camp, and an auto¬
mobile was used to great advantage. The levelman and two rodmen were
taken to their work in the morning and the car was then available for the
geologists in scouting for outcrops. Flags consisting of cheesecloth 18x18
inches on a lath staff, were placed upon the exposures. The location of the
flag was usually determined by means of a Brunton compass and by pacing
to the nearest land or road corner, and its position and number were noted
on the map. A similar map or a tracing, together with detailed information
concerning the flag locations, was furnished the levelman for his guidance.

Key Rocks

Coal No. 2 (Colchester or Murphysboro) was found to be the most
useful key rock because it had been opened up at many places where all
consolidated rocks were otherwise covered by glacial deposits. Further¬
more, information about the coal was more readily obtained than that con¬
cerning any other bed. Since the St. Louis limestone is commonly harder
than the overlying and underlying beds and was rather easily discovered, its

OIL INVESTIGATIONS

base was frequently used as a key horizon. In the vicinity of Rushville the
Springfield (No. 5) coal, lying 120 to 130 feet above the coal Xo. 2, was
followed ; elsewhere other beds were used to a limited extent.

STRATIGRAPHY
General Statement

The rocks of the area under discussion belong to two distinct types:
namely, (1) unconsolidated and (2) consolidated. The unconsolidated
rocks consist of material deposited by the present streams and called
alluvium; that transported by the wind and designated as loess; and that
deposited by the continental ice sheet and known as drift. The consolidated
rocks are much older, were deposited earlier, and are such ordinary kinds
as sandstones, limestones, and shales.

Unconsolidated Rocks
alluvium

The alluvium is confined for the most part to the present valleys,
where its thickness ranges from a few feet to 80 or more. It is for the most
part clay or sand or a mixture of both of these, but at some places is
coarser material. It is the first material penetrated in most of the wells
which are located in the valleys.

LOESS

Over the drift in many places is a covering of fine material known as
loess which is believed to have been carried and deposited more or less
exclusively by the wind. As a rule it is thicker along the bluffs overlooking
the larger valleys, and thinner farther back from the streams. Because of
this localized distribution and peculiar composition, which in some cases, at
least, is very similar to finely ground glacial material or rock flour, the loess
is believed to have been swept out from the glaciers by streams, spread out
over the flood plains, and then after the floods subsided and the material
became thoroughly dry, picked up and deposited over the neighboring
uplands by the wind. In texture it is intermediate between clay and sand.
Although unconsolidated, when undercut it is capable of standing in vertical
or slightly overhanging clififs (see figure 2). Another characteristic is its
division by joint planes into vertical columns. The thickness of the loess,
like that of the drift, varies from place to place; but in the area under
discussion it is especially thick along the western bluffs of Illinois River
(see figure 3).

THE AREA SOUTH OF THE COLMAR OIL FIELD

Fig. 2. Loess in the west bluff of Illinois River below Frederick.

Fig. 3. Loess hills above the outwash plain, looking toward Illinois River near
Frederick.

DRIFT

The drift belongs to one of the earlier periods of glaciation, the Illinoian.
Nearly everywhere in this area it conceals the bed rock and adds much to
the labor of the geologist in determining the position of the bedded rocks.
The drift contains fragments of many kinds of rock (limestone, sandstone,
granite, gneiss, schist, and others) over which the glacier or ice sheet
passed.

OIL INVESTIGATIONS

In places the constituents are assorted into clay, sand, gravel, and
bowlders; and in others they may be mixed together in a heterogeneous
mass. In this area the drift is for the most part fine material containing
few large bowlders. At most places outside of the valleys the drift is the
first material penetrated by the drill and in places the presence of bowlders
in the soft material deflects the drill so as to produce a crooked hole which
has to be abandoned.

Consolidated Rocks

GENERAL DESCRIPTION

The consolidated rocks of interest to the oil operator in this region
include the formations from the lower part of the “Coal Measures” down
to the St. Peter sandstone which underlies the Trenton limestone.

At different places in the area all of the formations down to, and includ¬
ing, the Keokuk limestone are exposed and may be studied in detail. Below
the Keokuk the beds are known from samples obtained by drilling.

The inserted generalized section serves as a key to identify the forma¬
tions on the outcrop or in drillers’ records.

The following is a composite section from measurements of various
outcrops in the region.

Composite section of exposed rocks

Pennsylvanian series

Carbondale formation

Ft. In.

A. Limestone, nodular, bluish black. 6

B. Shale, hard, black, carbonaceous, slate-like, with nodules

or concretions of hard, dark limestone. Large Lingulae

and Orbiculoidece . 2 6

C. Coal, Springfield (No. 5), broken by clay seams and

slightly faulted. Mined. The Mt. Sterling 18-inch bed
is probably the same. 5

D. Commonly covered, the exposed portions consisting of

shales and underclay. 7

E. Limestone, nodular or brecciated. Exposed at Mt. Sterling,

but not noted so fully developed at other places. 3

F. The first interval of twenty or thirty feet beneath the
Springfield (No. 5) coal is commonly covered. Sandy
shales and shaly sandstones, the layers of which in places
thicken up and form more massive sandstones. In places
cementation has been more pronounced, resulting in
harder and more resistant layers. In still other places
more thorough cementation has developed large flat con¬
cretions, which are more conspicuous where weathering
has removed the adjacent parts of the layers. Massive
sandstone in places, shales in others. The uneven erosion

THE AREA SOUTH OF THE COLMAR OIL FIELD

Ft. In.

surface at the base probably represents an unconformity.
More or less of the whole interval of 100 feet from the
Springfield (No. 5) coal to the limestone below is subject

to variation in constitution. 90

G. Limestone, dark gray. Ranges from 6 inches to 7 feet in
thickness and is nodular in places. Contains Chonetes
mesolobus, Productus, Crinoids, and other fossils. 4

H. Shale, hard, black, carbonaceous, and slate-like, which may

be somewhat softer at the base. It contains flat and
spherical concretions of dark limestone; Orbiculoidece and
Lingulcz are common. 4

I. Shales, soft blue clay; at some places 16 or 18 feet thick

and at others only 2 or 3 feet, or wanting. This irregu¬
larity in thickness is due to irregular deposition. The bed
of black shales above is wavy as a result of this variation 12

J. Coal, Colchester (No. 2), mined. This coal with the

overlying black shale and limestone is the most constant

horizon in the Pennsylvanian in this part of the State.... 2 6

Pottsville formation

K. Underclay and shaly clay. 2 6

L. Shales, soft clay, 1 to 10 feet in thickness. 6

M. Limestone, nodular, conglomeratic, or brecciated. 3

N. Clay or shale or shaly clay which becomes more sandy

toward the bottom and passes into sandstones. This is
the Cheltenham clay horizon, the clay being especially
well developed and valuable at some places. 14

O. Coal which ranges from 6 inches to 18 inches in thickness

and which may consist of two beds. It is commonly
called No. 1. 1

P. Shales, blue, clayey, and sandy, grading into sandstones.... 15

Q. Sandstone, irregular with some sandy shale. 5

Marked unconformity

Mississippian series

St. Louis limestone

R. Limestone, hard, bluish gray. Portions of the limestone
are in regular layers, and other portions are decidedly
irregular. In places the limestone is brecciated, the
angular pieces being almost exclusively limestone, and in
others the limestone is decidedly sandy. In the lower
part of the formation lenses of sandstone are present
which seem to be formed of sand which was washed into
cavities . 20

Salem and Warsaw formations

Thin- to thick-bedded sandy limestone or dolomite. Resembles
very fine-grained, limy sandstone. Generally has yellow
to brownish-yellow tint. Toward base is compact, bluish
limestone. Dull sound when struck with hammer; this
characteristic is helpful in distinguishing Salem from St.
Louis which rings when struck. 18

OIL INVESTIGATIONS

Feet

120

Oil

sand

Fig. 4. Graphic sections :

j. From measurements on outcrops (see “Composite section, page 14).
2 . Log of Hoing No. 1 well.

THE AREA SOUTH OF THE COLMAR OIL FIELD

Ft. In.

Limestone, shaly, and blue, shales, some of which are filled with
fragments of bryozoans and small shells. Small geodes

are present in places. 24

Base not exposed. Underlying Keokuk limestone exposed in
region but no continuous section from Salem downward
could be found.

Figure 4, section i is a graphic representation of the section given
above, including the beds to the base of the St. Louis limestone. By taking
No. i in connection with the graphic log of the Hoing well on the left,
(No. 2 ), the reader may gain a definite idea of the beds to be penetrated in
drilling to the oil “sand”.

CARBONDALE FORMATION

The Carbondale formation includes all of the beds from the top of
coal No. 6 down to the base of coal No. 2. The former coal is not present
in the area under consideration.

Exposures at few places show beds higher than a few feet above coal
No. 5, which lies 50 to 100 feet below coal No. 6 in other parts of the State.

Fig. 5. Colchester (No. 2) coal and overlying black, concretionary shales
west of Rushville.

In the vicinity of the Colmar oil field most of the coal-bearing rocks
were eroded before glacial times, and in many places the first rocks under
the drift are Mississippian limestones. Toward the south and east, the

2—B—31

OIL INVESTIGATIONS

Carbondale is present in greater thickness. Near Pleasant View 130 feet
of this formation was measured.

The Carbondale consists largely of shales and sandstones, but it also
contains thin beds of limestone, underclay, and coal. Coal No. 2
(Colchester) is one of the most persistent beds of the Pennsylvanian series
in Illinois. In spite of its thickness of only 24 to 30 inches, it has been
opened up at many places along the outcrop. Directly above coal No. 2 or
separated from it by a few feet of soft, clay shales, is a bed of hard, black,
carbonaceous, slate-like shale similar in appearance to that above the
Springfield (No. 5) coal (see figure 5). It contains nodules of hard, dark
limestone and fossil Orbiculoidea and Lingula which are smaller than those
in the shales associated with coal No. 5. Above the black shales is a
stratum of fossiliferous limestone, here and there chert-like. In this phase
the fossils appear white against the dark background.

Coal No. 5, which is confined to a small area north of Rushville and
Pleasant Mew is commonly 5 to 6 feet thick and contains clay seams that
cut across the bedding planes of the coal. The beds above coal No. 5 are
very similar to those above coal No. 2. The roof is a hard, black shale
overlain by a nodular limestone containing fossils. In the shale are nodules
and fossil shells of Orbiculoidea and Lingula which are larger than those
in the shale above coal No. 2. Below the floor clay of coal No. 5 is a
nodular limestone not unlike that beneath the Colchester coal.

POTTSVILLE FORMATION

The Pottsville formation includes all beds from the base of coal No. 2
to the base of the Pennsylvanian series. Like the Carbondale formation
it too is made up for the most part in this region of shales and sandstones,
but contains minor amounts of limestone, underclay, and coal. A few feet

Fig. 6. Unconformity at base of Pottsville, Harrison Branch, north of Huntsville.

The diagram above point marked “X” represents hillside outcrops, that below “X" repre¬
sents longitudinal section of stream bed.

beneath coal No. 2 is a bed of limestone which is either nodular or brecciated
and is not unlike the St. Louis, but can be readily distinguished from it
where fossils are present. A thin coal is found beneath coal No. 2 at many

THE AREA SOUTH OF THE COLMAR OIL FIELD

places, but owing probably to its lenticular nature no single bed persists
over a large area.

The “Coal Measures” rocks were deposited on a former land surface
with hills and valleys; consequently the thickness is extremely variable. The
Pottsville formation lies at some places on the St. Louis limestone, at
others on the Salem formation, and elsewhere on still older formations.
Such a relationship is called an unconformity since the normal sequence
of deposition has been interrupted by a period of erosion. Figure 6 is a
sketch showing the unconformity at the base of the Pottsville in Harrison
Branch, north of Huntsville.

ST. LOUIS LIMESTONE

In most places the St. Louis is a brecciated, poorly bedded limestone.
Well-defined layers are exceptional. Most of the angular fragments are
limestone and vary in size from grains to blocks 2 feet or more in diameter
(see figure 7). The color is blue at most places, although here and there a

Fig 7. Brecciated and conglomeratic St. Louis limestone east of Birmingham.

yellowish tint is noticeable. The limestone is barren of fossils, except large
hemispheres of the coral Lithostrotion canadense, which are harder than
the surrounding stone and must have collected as residual material on the
old St. Louis surface as the limestone weathered away, since most of them
are now in the base of the Pottsville sandstone.

When the St. Louis was land surface, caverns were formed in the
limestone as the result of solution by acid waters, just as caves now form

OIL INVESTIGATIONS

in limestones. Later the Pottsville was deposited on the St. Louis, and
some of the sand settled down into the old caves as shown in figure 8.

The St. Louis commonly has a thickness of 18 to 20 feet but in places

Fig. 8. Caves in St. Louis limestone filled by Pottsville sands. (Photo by Rich)

Fig. 9. Erosion planes in the St. Louis limestone in Harrison Branch north of
Huntsville.

it reaches more than 30 feet. In many parts of the regi n it has been
completely removed by pre-Pottsville erosion.

THE AREA SOUTH OF THE COLMAR OIL FIELD

The surface on which the St. Louis was deposited was not rough ; the
greatest departure from a level noted is 8J4 feet in a horizontal distance of
100 feet in Williams Creek about 3 miles northwest of Huntsville. Besides
the unconformities at the top and bottom, the St. Louis contains erosion
planes as shown in figure 9.

SALEM FORMATION

Below the St. Louis, and in unconformable contact with it, is a
variable thickness of yellowish, magnesian limestones, limy shales, and
limy sandstones correlated with the Salem formation. In many places
difficulty is experienced in correctly classifying the material as limy sand¬
stone or as impure limestone. Geodes are abundant , but fossils are scarce.
When struck with a hammer the Salem gives a dull sound, in decided
contrast to the ringing sound of the St. Louis limestone.

Thirty feet or more of the Salem was measured in the region, but
because of the unconformities at top and bottom, and also because of the
similarity between the basal beds of the Salem and the top strata of the
Warsaw, the thickness of the former is uncertain.

The following section is typical of the Salem in this region.

2 .

1 .

Measured section of Salem formation along stream and road between

secs. 5 and 6 , T. 2 N., R. 3 W.

Ft.

Limy shales, impure, yellowish, and bluish, and impure yellowish
limestones with chert and quartz geodes at a number of horizons.

The layers are more massive at the base. 20

Not exposed, probably shale. 12

Shales, blue. 4

Limestone, impure and yellowish, with bryozoa and Productus . 4

Clay shale, blue; and sandstone. 3

In.

WARSAW FORMATION

The Warsaw formation in this region is composed of 30 to 40 feet of
interbedded blue clay shales, and thin, impure limestones. The shales
contain abundant bryozoans, and in the limestones a large spiral fossil of
this class known as Archimedes is very characteristic.

The following sections show the variable nature of the Warsaw in this
region. They probably include some of the overlying Salem since it is
impossible to determine the contact between the two.

Section of part of Warsaw formation in the south central part of

sec. 14 , T. 3 N., R. 4 W.

(Section may contain few feet of Salem formation)

Ft. In.

3. Clay shales, hard, blue; and sandstones with very little lime, yellow,

and like Salem at base. 8

OIL INVESTIGATIONS

Ft. In.

2. Limestone, crystalline, massive, grading up into sandy limestone, yel¬

low ; large Archimedes . 10

1. Clay shales, soft, blue, and fossiliferous. 2 6

Section of part of Warsaw formation in the NE. cor. sec. 26 , T. 3 N., R. 4 W.

Ft. In.

2. Limestone, thick, reddish brown, crystalline, with sandstones between.

The upper limestone contains a large roseate brachiopod and the

lower one contains Archimedes, corals, and brachiopods. 12

1. Clay shales, soft, blue, filled with bryozoans, brachiopods, pelecypods,

and Archimedes . 5

KEOKUK LIMESTONE

The Keokuk limestone is the lowest formation exposed in the region.
It consists of 30 feet or more of gray, crystalline, very fossiliferous lime¬
stone, which grades upward into the Warsaw shales. The main body of
the Keokuk is evenly bedded as shown in figure 10.

Fig. 10. Keokuk limestone near Plymouth. (Photo by Rich)

BURLINGTON LIMESTONE

The Burlington limestone does not outcrop in the region, but it is
believed to be represented by certain cherty limestones penetrated by the
drill while passing through the base of the Mississippian or so-called “first
lime”. In the Littleton well, recently drilled, the lower part of the lime¬
stone from 270 to 445 probably represents the Burlington.

THE AREA SOUTH OF THE COLMAR OIL FIELD

KINDERIIOOK AND UPPER DEVONIAN SHALE

The “first” and “second” limes are separated by about 200 feet of shale.
The upper 100 feet, usually a bluish-gray, sandy shale, represents the
Kinderhook. Samples from the Littleton well show 100 feet of Kinderhook
shale underlain by 100 feet of dark gray to olive shale containing Sporangites
which prove it to be of Upper Devonian age. The lower part contains
shales of somewhat lighter color.

DEVONIAN LIMESTONES

A thin, non-magnesian limestone usually reported as gray, and in some
places said to contain pyrite, underlies the shale mentioned above. In most
of the wells thus far drilled this limestone is not more than 15 feet thick,
although it is difficult to distinguish from the underlying limestone. It
forms the upper part of the drillers’ “second lime.”

NIAGARAN FORMATION

Below the limestone described above is a gray to pink crystalline dolo¬
mite which probably represents the Niagaran. Where it is present, it forms
the lower part of the “second lime” and would probably not be distinguished
from the Hamilton limestone above.

Since the Niagaran was deposited on an eroded surface of Maquoketa
shale and was itself exposed to erosion before the overlying Hamilton was
deposited upon it, the thickness of the Niagaran is extremely irregular.
In some places it was completely eroded. The combined thickness of the
Hamilton and Niagaran is rarely more than 50 feet.

In the western part of Illinois, the Niagaran is closely associated with
oil production. It contains the gas in Pike County, where the dolomite is
also oil soaked in places. On the outcrop in Calhoun County near Batch-
town, the Niagaran is a fine-grained, bufif-colored dolomite that falls to
powder under the hammer, and is so porous that it could easily act as a
reservoir for oil and gas. The “broken” sand so often reported at the
base of the “second lime” is probably the porous basal part of the Niagaran.
The oil sand probably represents reworked material at the base of the
Niagaran and is properly classed as part of that formation.

ORDOVICIAN FORMATIONS

Below the Niagaran the drill penetrates a variable thickness of shale,
generally bluish or greenish and usually easily distinguished. In the
Griggsby well in the W. y 2 SE. % sec. 20, T. 4 N., R. 4 W. the Maquoketa
or Richmond shale as it is called, is 187 feet thick and in other wells that
penetrate the formation, it generally ranges from 180 to 200 feet. Recent

OIL INVESTIGATIONS

drilling seems to indicate that 6 or 8 miles north of the Colmar field, the
Maquoketa may be much thinner than indicated above; probably on account
of erosion before the Hamilton was deposited. In the latter area the
Maquoketa also contains shaly textured dolomites in contrast to the typical
shales further south.

Below the Maquoketa is the Kimmswick-Plattin (Trenton) limestone
which in the region covered by this report is non-magnesian, gray, and
somewhat crystalline. Thus far it has not been found to contain oil in the
western part of Illinois. South of this region, in Calhoun County, the
Trenton outcrops and is seen to be composed largely of shells. When struck
with the hammer, the odor of oil is very prominent.

About \y 2 miles north of Beechville, Calhoun County, the Trenton
contains a conspicuous amount of bituminous matter. The rock must have
been highly organic originally, and it is not unlikely that some oil originated
in this formation. Drillers in Illinois often report the odor of petroleum
from the Trenton. It was penetrated 200 feet in Griggsby No. 1 and it may
be 300 to 400 feet thick. Because of its compact nature, it does not tend
to be as favorable for accumulation as does the more porous A T iagaran, but
it should be tested in wells where the structure is favorable in order to
explore all possible oil horizons.

Position of the Hoing Oil Sand in the Section

The producing stratum lies beneath the “second lime” and at the base
of the Niagaran formation. Samples from producing wells show that it is a
round-grained quartzitic sand of variable thickness.

The sand exists in lenses and appears to be material that was washed
into the valleys and low areas when the Maquoketa shale was land surface
and exposed to erosion. It was reworked, of course, by the Niagaran sea.
Its areal distribution is spotty and in many places the drill passes from the
“second lime” directly into the Maquoketa shales, with no intervening sands.

It is possible that the lower part of the Niagaran dolomite is in some
places responsible for a show of oil but it is believed that important accumu¬
lation is dependent on the presence of the more porous sand. It is obvious
that the presence of the latter cannot be predicted in advance of the drill.

STRUCTURE
General Statement

The significance of the unconformities described under “Stratigraphy”
is shown graphically in figure 11, the unconformities being represented by
the irregular contact lines between different formations. Such contact
planes are simply ancient land surfaces, some of which had almost as

THE AREA SOUTH OF THE COLMAR OIL FIELD

much relief as the surface today; whereas others exhibit a relief of only
a few feet.

In selecting a key rock the elevation of which is to be determined
throughout a region, in order to learn the position of underlying oil sands, it
is necessary to know that the bed is approximately parallel to the deeper
beds or that the departure from parallelism is regular and determinable.
An unconformable contact between two formations is worthless for this
purpose in Illinois if the irregularities in the old surface as shown by the
plane of contact exceed 15 feet. For example, the contact between the
“Coal Measures” and the Mississippian limestones or “first lime.” as shown
in figure 11, would be valueless in determining the position of the Hoing

Fig. 11. Diagram showing significance of unconformities in the Colmar region.

sand, since levels on this contact would merely determine the height of the
hills on the old land surface rather than any folding which the beds had
undergone. On the other hand, the base of the St. Louis limestone, although

OIL INVESTIGATIONS

in unconformable contact with lower formations, serves as a safe horizon
because the irregularities in the plane of contact are slight.

So far as is known, regardless of the many oscillations of the region
above and below sea level and despite the long periods of time represented
by the formations and their unconformities, there was practically no warping
or folding of the beds from the time the Hoing sand was deposited until
after the “Coal Measures’’ were laid down. Such folding as then took
place affected all the beds alike. Were it not for this fact, geological work
on beds at the surface would be almost useless in determining underlying
structures. During the submergence which followed the exposure of the
St. Louis limestone as a land surface, it is possible that the sinking was
slightly greater toward the northwest since we now find in that direction
an increasing interval between the base of the St. Louis and coal Xo. 2 lying
above. The interval varies from about 45 feet in southeast Schuyler
County to about 75 feet in the vicinity of Colchester.

Relation of Folds in an Oil-bearing Stratum to Accumulation

In most of the oil fields of the State, the accumulation is intimately
connected with the upward folds in the strata. It is the usual experience to
find the oil near the crests of the anticlines or where terraces exist on the
sides of the anticlines. Both types are illustrated in the main oil fields of
Lawrence and Crawford counties.

The fact that every known field in Illinois is surrounded by wells
which tap only salt water, is strong evidence that the latter is a most
important factor in determining where the «oil will accumulate in a sand
that has been folded in undulations. If the sand is practically saturated
with salt water, the result is generally a forcing of the oil int} the crest
of the fold as shown in figure 12, A. In case of partial saturation, the oil
is found farther down the sides of the folds and the crest may be dry or
it may contain some gas (fig. 12, B). If the sand is dry, the oil is per¬
mitted to collect in the basins or synclines, and the anticlines prove unpro¬
ductive (fig. 12, C).

The productive part of the sands in the southeastern Illinois fields is
near the crest of the well-defined La Salle anticline or on terraces which
are part of this same fold. On the sides of the anticline, salt water fills
the producing sands almost to the crest.

In the western part of Illinois, however, many of the conditions are
different from those in the fields just mentioned, and it would not be sur¬
prising if oil is found in positions entirely different from those better known
heretofore.

In attempting to locate possible undiscovered fields in western Illinois
the following facts must be given due consideration:

THE AREA SOUTH OF THE COLMAR OIL FIELD

1. The structural features—that is, folds—are small in area and in
magnitude. The crests of many of the domes and anticlines are not more
than 20 or 30 feet high.

3rd.drill hole

Fig. 12. Diagram showing conditions governing oil accumulations:

A. In oil sands saturated with salt water.

B. In oil sands partly saturated.

C. In sand containing no salt water.

OIL INVESTIGATIONS

2. The oil-bearing horizon is extremely variable in thickness and in
character.

3. Drilling already done shows that oil and salt water exist in separated
areas and at so widely different elevations that no lateral connection be¬
tween the deposits of one area with another is conceivable.

1. In the eastern part of Illinois the beds at the crest of the La Salle anti¬
cline lie 500 feet higher than in the basins bordering the fold. The anti¬
cline is of sufficient magnitude to be easily identified and traced, and
its influence on petroleum accumulation is clearly defined. In the
western part of the State, however, the beds dip gently eastward, and
the folds that have developed are merely small irregularities in, or
interruptions to, the general dip. The altitude of the sand has been
determined from outcrops of beds at the surface, the parallelism of
the strata being assumed. In the Colmar field, the sand is parallel to
the beds lying above and shows the same folding as the coal. How¬
ever, the drilling of domes and anticlines where the crests rise only
20 or 30 feet, is recommended with considerable hesitancy.

2. The sand that contains the oil was probably deposited only in the valleys
and basins in the Maquoketa shale. Consequently the bed is not con¬
tinuous, but exists as lenses of various shapes and sizes, entirely
separated from one another. This assumption is confirmed by the
records from some of the wells in which little or no sand was found at
the Hoing sand horizon.

3. The location of the salt water in the territory thus far studied presents
a serious problem. In the Colmar field the sak water is found in the
lower part of the sand on the terrace and also lower down the dip. At
the east end of the crest of the elongate dome, the Collins and Griggsby
wells showed a small amount of oil and no salt water; whereas at the
west end of the dome the Roberts No. 1 well, which taps the sand at
the same elevation as the wells named above, produces oil in commercial
quantities and is surrounded by wells lower down the dome which
produce only salt water, existing high in the dome, almost 50 feet
above the level of the oil in the Colmar field only three miles distant.
In the vicinity of Birmingham, and between this place and Augusta, a
number of wells have been drilled, and although the Hoing sand was
found in most of them and notwithstanding the fact that the highest of
these wells structurally, taps the sand at least 60 feet below the salt
water near the Roberts No. 1 well, careful investigation discloses the
absence of salt water in the lower wells. In fact, below about 100
feet where fresh water required casing, it was necessary to add water
to most of these wells for drilling purposes.

It is clear then that regardless of position above sea level, certain
areas may be saturated with salt water and possibly with accompany-

SURVEYED IN COOPERATION WITH

U. S. GEO -OGICAL SURVEY

ILLINOIS STATE GEOLOGICAL SURVEY

GOVERNOR E F. DUNNE. T. C. CHAMBERLIN, E. J. JAMES. COMMISSIONERS
FRANK W. DE WOLF, DIRECTOR

BULLETIN NO. 31. PLATE I

I Beardatown

R. 1 W.

MAP OF PARTS OF SCHUYLER, BROWN. ADAMS AND HANCOCK COUNTIES

SHOWING POSITION OF UNDERLYING BEDS BY MEANS OF CONTOURS ON COAL NO. 2

By William C. Morse and John L. Rich. 1915.

THE AREA SOUTH OF THE COLMAR OIL FIELD

ing trapped oil, whereas between these areas there may be no oil nor
salt water.

The explanation of the features mentioned is probably to be found
in the fact that the sand now exists in separated lenses surrounded
at the sides as well as at the top and bottom by impervious beds, and
accumulation is free to progress in each lens independently as outlined
under the topic “Conditions governing accumulation in the Colmar
field,” to which the reader is referred.

Under these conditions the degree of saturation by oil and salt
water will govern whether accumulation will take place at the top of the
folds, in terraces lower down, or in the synclines.

Taking all features into consideration, the Survey recommends that
the first test holes be located near the crests of the domes and anticlines
pointed out under the topic “Recommendations.” In doing so the operator
will be prospecting the areas that are normally the most favorable. If the
crests are found to be barren of oil and to contain no salt water, other
wells should be drilled in positions to test the sand at lower elevations,
preferably terraces as shown on the structure map. In locating wells on
a flat portion of the sand (terrace) it should be remembered that the accumu¬
lation is likely to be at the downward-dipping edge of the terrace as shown
in figure 12, B. Should the terraces prove barren of oil and salt water, it
is recommended that at least a few of the synclines be drilled, the suppo¬
sition being that in the absence of salt water in the higher structures the
oil would be in the troughs.

Detailed Structure

GENERAL STATEMENT

Elevations upon either or both coal No. 2 and the basal contact of the
St. Louis limestone were secured wherever possible at intervals of one
mile or less. These elevations were recorded upon a study map which
revealed the following general structure of the two beds.

In general coal No. 2 dips to the south of east—from the highest ele¬
vation of 630 feet, in secs. 25 and 26, T. 3 N., R. 5 W. (Augusta), Han¬
cock County, to the lowest elevation of about 500 feet along Illinois River
in the vicinity of Browning and Frederick, Schuyler County. Upon this
larger structure in places there are some minor features which take the
forms of small domes, anticlines, terraces, and synclines. The general dip,
however, persists over large areas, and the coal bed lies nearly flat in a
belt 4 to 6 miles wide stretching from Littleton to a point beyond Mabel
(see Plate I) and probably in a similar belt stretching southeast from Little-
toti through Rushville to Pleasant View, although elevations in this latter
belt are very meagre because of the lack of coal outcrops.

OIL INVESTIGATIONS

Like coal No. 2, the St. Louis limestone in the region under discussion,
has a general dip to the south of east. It dips from the highest elevation
of 580 or 590 feet in the vicinity of Huntsville and the northwest part of
Schuyler County to the lowest elevation of about 450 feet along Illinois
River between Browning and Frederick. Furthermore, the total amount
of dip of these two horizons is about the same, being 130 feet for coal No.
2 and 140 feet for the St. Louis limestone. Upon this general structure
of the St. Louis limestone there are also minor structural features similar
to those shown by coal No. 2.

Because of the general parallelism between coal No. 2 and the St.
Louis limestone, and especially because in areas where exposures of the
one are absent, outcrops of the other are commonly present, it has been
regarded advantageous to combine the data regarding the two beds in a
single map on which the altitude of the beds has been shown by means
of contour lines. Where coal No. 2 is present the contours represent ele¬
vations run to that bed; where it has been eroded, its former elevation was
determined by running elevations to the base of the St. Louis limestone
and adding to this figure the average thickness of beds between the base
of the St. Louis and coal No. 2. This thickness is 40 feet at the southeast
part of the area and increases regularly toward the northwest as explained
on page 26. At the northwest corner of Schuyler County the interval is 75
feet, as determined by Mr. Hinds in his work in the Colchester and Macomb
quadrangles.

FOLDS SHOWN BY COAL NO. 2 AND ST. LOUIS LIMESTONE

A minor dome has been formed in the coal to the east of Littleton,
its apex being in secs. 12 and 13, T. 3 N., R. 2 W. (Littleton). The bed
in the immediate vicinity rises from about 550 feet on the southeast and
from a little less than 580 feet on the north to its maximum elevation of
about 600 feet. Both the St. Louis limestone and coal No. 2 between secs.
8 and 21, T. 2 N., R. 2 W. (Buena Vista), lie at elevations 10 to 20 feet
higher than they do in the immediate vicinity to the north, east, and south,
as indicated on the map (Plate I). It must be noted, however, that the
rise of the beds is a very slight one.

Coal No. 2 in secs. 14 and 9, T. 1 N., R. 2 W. (Woodstock), and the
St. Louis limestone in sec. 33, T. 1 N., R. 2 W. (at Ripley), reach elevations
20 to 30 feet higher than they do in the adjoining territory. Between
these points elevations of the beds are not available for the reason that
they are not exposed at the surface. The area of elevated strata is
probably about as that represented on the map (PI. I) within the limits
of the 540-foot contour line. It is also a minor feature with unknown limits.

In sec. 7, T. 1 N., R. 2 W. (Woodstock), and in secs. 10, 11, and 13,
T. 1 N., R. 3 W. (Missouri)—that is, at Scott Mill—the St. Louis lime-

THE AREA SOUTH OF THE COLMAR OIL FIELD

stone reaches an elevation 50 or 60 feet higher than it does to the south.
Although elevations are not obtainable to the north, the limits of the elevated
beds are probably correctly shown by the 570-foot contour line. Coal No.
2 lies at a higher elevation along what seems to be a small anticline whose
axis runs southwest from sec. 5, T. 1 N., R. 3 W. (Missouri), through
sec. 13, T. 1 N., R. 4 W. (Pea Ridge) ; but here also the rise is only a few
feet. The coal bed also rises rather rapidly westward from 520 feet to 580
feet in sec. 4, T. 1 S., R. 3 W. (Mt. Sterling) ; but unfortunately lack of
exposures and of field study makes it impossible to state now whether this
bed continues to rise in this direction or culminates here in its highest
observed point.

In the area under discussion the greatest elevation which coal No. 2
attains is near the county line slightly north of west of Huntsville where the
bed is more than 630 feet above sea level. The exact nature of this struc¬
ture is not clear, because the bed is concealed to the west. It seems probable
that it is an elongate dome, although it may be a terrace from which the
bed rises to the north or to the west, or in both directions. The structure is
more pronouncedly revealed by the contours on the base of the St. Louis
limestone which reaches its maximium height slightly to the northeast of
that of coal No. 2. or along a curved line extending from secs. 34 and 35
northwest to sec. 17, T. 3 N., R. 4 W. (Birmingham). From the east the
St. Louis rises rather rapidly from 530 or 540 feet to 580 or 590 feet along
this belt of elevated beds. Unfortunately there are no outcrops to the west
which would show the altitude of the limestone farther in this direction,
but the suggestions are that the bed dips to the west, beyond the belt of
elevated strata, thus forming an elongated dome. If on the contrary the
limestone rises to the west then the structure is a terrace rather than an
elongated dome. At any rate, there is a sudden arrest of the rapidly rising
limestone along this belt of elevated strata and there is a terrace on the
steeper portion of the dipping limestone two miles east of Huntsville as
shown on Plate I. The Huntsville uplift is represented graphically on the
map by contours based on both the limestone and coal elevations.

RECOMMENDATIONS

Because the oil-producing bed is lenticular and is absent over consider¬
able areas, the selection of favorable locations for drilling is fraught with

more than the usual element of uncertaintv. There is little doubt that in some

of the areas described below, the sand is absent, and in this event there will
be no accumulation of oil despite the favorable geological structure. It
is hoped that the sand is present in at least a few of the areas listed below
so that the combination of porous beds with favorable dips may be tested.
The presence or absence of the sand cannot be predicted in advance of the
drill.

OIL INVESTIGATIONS

The general plan of prospecting here proposed recommends the drilling
of the more pronounced domes and anticlines first. Further testing will
then depend on (1) the presence or absence of the Hoing oil sand, and (2)
if present, whether it is (a) dry, (b) contains oil, or (c) contains salt
water (see figure 13 and discussion on pages 26-29).

1. Ordinarily the dome on top of the terrace-like area in parts of secs.

7, 8, 17, and 18, T. 3 N., R. 4 W. would be recommended for drilling.
However, the Henry Pearson well in the NW. Ft sec. 19, which taps the
Hoing sand horizon not more than 10 feet below the top of the dome,
struck neither oil nor salt water. Wells in sec. 9, about one mile from the
top of the dome and only slightly below it structurally, proved to be dry,
and no salt water was found. A trace of oil was reported in the A. D.
Lawton well in sec. 1, T. 3 N., R. 5 W. about 2 miles northwest of the
dome mentioned. The Beard, Stark, and Gordon wells located from 2
to 4 miles southwest of the dome and structurally 25 to 30 feet lower
showed neither oil nor salt water. Thus, the dome does not seem favorable.

The only other location not tested is the top of the dome near the east
side. A hole at the SW. cor. SE. 34 NW. Ft sec. 17, T. 3 N., R. 4 W.
would test the oil horizon on the side of the dome from which the oil
might have come.

2. In the shaded parts of secs. 26, 27, 34, 35, T. 3 N., R. 4 W. and secs.

2 and 3, T. 2 N., R. 4 W., as shown on the map, the beds lie approximately
flat. They dip noticeably east, south, and north from this area. A well
in the SE. cor. SW. Ft SW. 34 sec. 35, T. 3 N., R. 4 W. would test the
sand on top of the terrace near its side where conditions are favorable
for accumulation.

3. If the sand is present in the terrace mentioned under 2, and if it
should prove devoid of oil and salt water as well, although sufficiently
porous to hold these materials, it is suggested that a hole be drilled at the
center of sec. 22, T. 3 N., R. 4 W. where the sand lies in a syncline and
about 65 feet lower than in the top of the dome 2 miles northwest. It
must be remembered that this test is not recommended until after the
terrace described above is drilled.

4. The eastern end of a small terrace covers parts of secs. 14, 15, 22.

23, and 27, T. 3 N., R. 3 W. If the coal were present, its elevation would

be about 596 on this terrace, about 35 feet lower than on the terrace

described above. The beds dip north, east, and south, and although it N
is not a large feature, the terrace seems to merit at least one test which

might well be located in the NE. cor. SE. Ft sec. 22. T. 3 X., R. 3 W.

There is considerable area to the east from which the oil might have been
derived, and the flattening of the beds here is favorable for accumulation.

5. Outcrops at the east quarter corner of sec. 8 and in the NW. cor.

sec. 21, T. 2 N., R. 2 W. (Buena Vista) show that the beds lie 20 or 30 ^

THE AREA SOUTH OF THE COLMAR OIL FIELD

feet higher than in the surrounding sections and probably show that a
slight dome exists in the area shaded on the map, covering parts of secs.
4, 8, 9, 10, 16, 17, 20, and 21, T. 2 N., R. 2 W. A well in the center
SW. y sec. 9, would test the highest part of the dome. The center of
the SW. y sec. 16, would be an equally good location.

6. In the center of the SW. y NE. y sec. 13, T. 3 N., R. 2 W. the coal
lies 590 feet above sea level, slightly higher than in the surrounding area.
It is probable that the highest part of the arch lies /4 to ^4 mile northeast
of this outcrop, or at the northeast corner of sec. 13. The beds have a
slight dip in all directions from this point. In point of fact, this feature
is scarcely more than a terrace southeast of which the beds dip toward a
pronounced syncline. To the north and northwest in the Macomb quad¬
rangle the sand lies almost flat for 10 miles. A well near the NE. cor. sec.
13, T. 3 N., R. 2 W., would test the highest part of the low arch.

7. Outcrops in the northwest part of T. 1 N., R. 3 W. and in the north¬
east part of T. 1 N., R. 4 W. appear to reveal an anticline whose axis
extends from about the center of sec. 5, T. 1 N., R. 3 W. southwest through
the center of the west line of sec. 18. Field work has not been carried
southwest of this point. Along the axis the beds lies 20 or 30 feet higher
than at a distance of a mile or two on either side. If drilling is done along
this anticline it is recommended that the wells be located slightly east of
the axis as indicated.

8. In the area including parts of secs. 6, 7, and 8, T. 1 N., R. 2 W. and
secs. 1, 11, 12, 13, and 14, T. 1 N., R. 3 W. the beds are arched into a
dome. The dip on the south and east is greater than in other directions
and can be seen without instrumental leveling in the valley of Crooked
Creek. At the top of the dome the sand beds lie at least 50 feet higher
than in the syncline which borders it on the southeast. North and west
of the dome the dip is very gentle. Wells placed at the base of the blufif
in the NW. y sec. 7, T. 1 N., R. 2 W. or in the SE. cor. sec. 12 would
test the dome slightly east of the top where accumulation might reasonably
be expected.

9. A flat, elongate dome separated from the one just described by a
syncline, exists in parts of secs. 9, 10, 11, 14, 15, 16, 20, 21, 22, 23, 27, 28,
29, 32, and 33, T. 1 N., R. 2 W. Outcrops here are not as numerous as
would be desirable, but they indicate that from the area shaded on the
map the beds dip slightly in all directions. Structurally, the beds in this
dome lie about 30 feet lower than in the area described immediately above.

There is a considerable latitute for the selection of test wells in this
dome but it is recommended that drilling be done first in the east half of
the area shown by shading on the map. So far as structure is effective,
wells in the SE. y sec. 28, SW. y sec. 22, and center of sec. 14, T. 1 N.,
R. 2 W. would be equally favorable.

OIL INVESTIGATIONS

10. Northwest of Frederick, in parts of secs. 6 and 7, T. 1 N., R. 1 E.
and secs. 11 and 12, T. 1 N., R. 1 W., the beds lie flat; whereas east,
south, and northeast there is a noticeable dip. Northwest of the area,
exposures are lacking hut it is thought that the beds lie almost flat. Judging
from structure and without any knowledge of the sand or salt water, there
is a possibility of some accumulation along the outer edge of this terrace.
So far as can be determined from the outcrops a well in the SW. *4 SW.
J4 of sec. 7, T. 1 N., R. 1 E. would be located properly with regard to
structure.

If the normal oil-bearing horizon is barren of oil and salt water, it
would be well to test the syncline which borders the terrace on the north¬
east and is outlined on the map by the 500-foot contour line. Whereas oil
in synclines would be a new discovery for Illinois, it must be recognized
that such accumulation is possible, and is well known elsewhere.

11. Along the north line of T. 1 S., R. 3 W., Brown County, the beds
were found to rise noticeably toward the west, but field work was not con¬
tinued west of sec. 4 of this township where the coal lies 583 feet above sea
level or 60 feet higher than at the northeast corner of the township. It is
hoped that field mapping may be continued south and west during the sum¬
mer of 1915 to determine the position of the beds in that region.

LOCALITIES ALREADY TESTED

Of the wells drilled in the wild-cat territory to date, only two were
located where the structure appears favorable. The Henry Pearson well
near the center of sec. 19, T. 3 N., R. 4 W., (Birmingham), is near the high¬
est part of the dome northwest of Huntsville, and since it is dry, it is believed
that this well discredits the dome, although it is not located at the most
favorable part, namely, the eastern side of the dome as mentioned under
No. 1 of “Recommendations.”

A new well completed April 15 by Mr. H. E. Cary southwest of
Rushville in the NE. At SW. J4 sec. 11, T. 1 N., R. 2 W. is located at the
northeast side of a dome described under No. 9 of “Recommendations.”
This well was drilled to 915 feet, which is about 75 feet below the top of
the Trenton limestone. A small show of oil was noted near the top of
the Trenton, but no mention of oil is made in the Niagaran at the horizon
of the Hoing sand. A large amount of fresh water was found down to
about 400 feet. Samples from the Trenton here show that it is not dol-
omitic and that it would probably not be a good reservoir for oil. The
well is not regarded as favorably located as if it were two miles southwest,
near the crest of the flat dome.

Table 1. — Drill holes in the area south of the Colmar field

THE AREA SOUTH OF THE COLMAR OIL FIELD

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THE COLMAR OIL FIELD—A RESTUDY

By William C. Morse and Fred H. Kay

(In cooperation with the U. S. Geological Survey)

OUTLINE

PAGE

Original study of region and prediction of oil. 38

Restudy of the field. 38

Beds penetrated in drilling. 39

Position and depth of oil-bearing bed. 40

Possibility of lower sands. 40

Position of Hoing sand above sea level. 40

Conditions governing accumulation in Colmar field. 42

Oil-bearing bed. 42

Erratic position of salt water. 43

Origin of the oil.•. 44

Extension of Colmar field. 44

Summary . 45

ILLUSTRATIONS

PLATE PAGE

II Map showing location of wells in secs. 9, 10, 15, and 16, T. 4 N., R. 4 W.. 38

III Map of Colchester and Macomb quadrangles including Colmar oil field.... 44

FIGURE

13. Cross-section showing the position of the oil sand in the Colmar field. 43

TABLES

2. List of wells in Colchester and Macomb quadrangles. 47

( 37 )

ORIGINAL STUDY OF REGION AND PREDICTION OF OIL

The Colchester and Macomb quadrangles, in which the Colmar oil
field is located, were examined in 1912 by Llenry Hinds of the U. S.
Geological Survey in cooperation with the State Geological Survey.

In order to learn the position of the beds, Mr. Hinds determined the
elevation of coal No. 2 above sea level at a large number of places and
where the coal has been eroded, levels were run to outcrops of beds whose
distance below the coal is known. His maps, published as Plate I, Extract
from bulletin 23, State Geological Survey, May 1914, show a pronounced
doming of the strata between Plymouth and Colmar, the highest part lying
in secs. 19 and 20, T. 4 N., R. 4 W., where the coal would be 720 feet
above sea level were it not eroded. The dip toward the east and south is
greater than that toward the north and west.

At the time of Mr. Hinds’ field work no wells had been drilled closer
than 4 miles from the top of the dome, but the favorable nature of the
structure led him to suggest the possibility of petroleum accumulation in
the dome. He also mentioned the existence of a smaller dome in sections
29 and 30 north of Macomb. The following quotation is taken from his
report:

“Under those conditions (tilted beds saturated with salt water) accumulation
takes place in the anticlines or arches or at the upper borders of dipping porous areas,
(terraces [Editor]) where the porous rocks are at higher altitudes than in adjacent
areas. A glance at the accompanying structure map will show that one such anti¬
cline lies two miles northeast of Plymouth only four miles northwest of well Xo. 4
near Birmingham. It is, perhaps, significant that the best reported showing of oil
was in well No. 4, the one that is situated nearest the crest of this dome-shaped anti¬
cline, and it is unfortunate that at least one of the drillings was not made in the
more promising territory. A similar but less pronounced dome exists near Macomb”. 1

RESTUDY OF THE FIELD

Since the completion of Hinds’ report in 1912 and its publication
in May 1914, nearly 180 wells have been drilled in the region, of which
more than 130 located in secs. 9, 10, 15 and 16, T. 4 N., R. 4 \Y. are
productive (see Plate II). Roberts No. 1 well sec. 24, T. 4 N., R. 5 \\ .
and a new well on the J. M. Wear farm SE. J4 NW. 14 sec. 14, T. 4 NT
R. 4 W. are, up to date, the only commercially productive wells brought in
outside of the four sections mentioned above.

The large amount of information made available by the drill rendered
further study of the field desirable in order to determine (1) the position

’Hinds, Henry, Oil and gas in the Colchester and Macomb quadrangles: Ill. Geol. Survey
Extract Bull. 23, pp. 11-13, 1914.

( 38 )

ILT

T.4N. LAMOINE

ILLINOIS STATE GEOLOGICAL SURVEY

BULLETIN NO. 31, PLATE II

THE COLMAR OIL FIELD

of the sand above sea level, (2) the relation of the position of the oil sand
to that of the surface key rock, and (3) the conditions under which the
oil accumulated. The additional field work by the senior author in 1914
consisted of the collection of drill records and instrumental leveling to
determine the elevation of the wells above sea level.

BEDS PENETRATED IN DRILLING

Detailed descriptions of the formations are presented under the topic
“Stratigraphy” in the first report of this bulletin. The following log of
Griggsby No. 1 is presented, since it furnishes at a glance, knowledge
regarding the beds down to and including a large part of the Trenton
limestone. Most of the wells are drilled only to the normal oil-producing
horizon at the base of the “second lime” as shown on the printed log.

Records from the adjoining region are very similar to this one. except
that from some places, especially east and south of the field, they show a
greater thickness of material above the “first lime.” In the wells of the
producing field the coal-bearing beds lying beneath the drift are almost
entirely eroded; whereas farther east and south the “first lime” is found at
a considerably greater depth and is overlain by shales, sandstones, and
interbedded coals.

Drill record of Griggsby No. i well, W. G SE. G T. 4 A 7 ., R. 4 W.

Elevation above sea level 576 feet

Thickness Depth

Surface deposits Feei Feet

Soil and clay... 25 26

Carboniferous system
Mississippian series

St. Louis and Osage groups

Limestone, gray.

Mud ...

Limestone, white, sandy..

Limestone, gray, water at 115 feet.. ,
Limestone, white .

Kinderhook and Upper Devonian shales

“Lirst

lime”

Mud, white.

Shale, brown .

“Slate,” white, and mud.

Shale, brown.

“Slate,” white, and shale.

Mud, white.

“Slate,” white, sandy.

Shale, brown.

“Slate,” white, sandy.!'.

Devonian and Silurian systems

Limestone, gray, show of oil 425 to 432 feet, “Second lime”

145

180

210

220

260

270

290

311

378

385

400

434

OIL INVESTIGATIONS

Ordovician system Ft. In.

Richmond (Maquoketa) shale

“Slate” and shale. 187 621

Kimmswick-Plattin (Trenton) limestone

Limestone, white. 29 650

Limestone, brown. 155 805

POSITION AND DEPTH OF OIL SAND

The Hoing oil sand was named from the first producing well in the
field. It consists of well-rounded quartzitic grains and is lenticular in its
occurrence. It lies on the Maquoketa shale, and at the base of the “second
lime.” It is believed to have accumulated in the lower parts of the Maquo¬
keta surface and to have been reworked by the Niagaran sea. It repre¬
sents, therefore, the basal part of the Niagaran. In places it is overlain
by Niagaran dolomite and where the latter is eroded it is capped by the
Hamilton limestone.

POSSIBILITY OF LOWER SANDS

The only other horizon in the Colmar field in which oil might reasonably
be sought is the Trenton limestone which lies 100 to 200 feet below the
Hoing sand and is separated from it by shale. Samples of the Trenton
from the region of Colmar show that it is a pure limestone and does not
tend to be sufficiently porous to act as a reservoir for oil and gas. The
odor of petroleum and a small show of oil have been noted in places near
the top of the formation, but no accumulation has been found. The Trenton
was penetrated 184 feet in Griggsby No. 1 and it may be as much as 400
feet thick. In order to test all possible oil-bearing beds, the Trenton should
be penetrated by a few holes in each area where conditions are favorable.

The St. Peter sandstone which underlies the Trenton, has never pro¬
duced oil in Illinois. When penetrated in central and southern Illinois, it
generally yields an abundant supply of highly mineralized water. The
amount of salts increases toward the south.

POSITION OF HOING OIL SAND ABOVE SEA LEVEL

In order to show the parallelism between the beds outcroping at the
surface and the oil sand, as well as the similarity in the folds affecting all
of the beds down to and including the oil sand, Plate III has been prepared
by printing in red, over the former map showing the position of the coal
above sea level, a new set of contours which discloses the position and
nature of the dome in the oil sand.

The detailed structure of the oil sand, the determination of which
is made possible by the drilling of a large number of wells in a small
area, confirms in an extremely satisfactory manner the value of ascer-

3—B—31

THE COLMAR OIL FIELD

taining the structure of the outcropping beds prior to drilling. The crest
of the dome, as shown by the coal and the St. Louis limestone, is identical

in position with the apex as disclosed by the depth of the oil sand in the
Collins well in the SE *4 sec. 20.. T. 4 N., R. 4 W.

OIL INVESTIGATIONS

It must be remembered that most of the region is covered by glacial
deposits; and on the surface, instead of being able to see the bed rock over
a large area, the geologist is limited to scattered outcrops for his obser¬
vations, and it is to be expected that details of structure, such as terraces,
may not be disclosed if outcrops are separated by considerable distances.

Mr. Hinds’ coal contours and the contours on the oil sand by Mr.
Morse, differ only in detail. The axis as shown by the sand extends east
and west; whereas Mr. Hinds’ map pictures it as a line extending a few
degrees north of west. Figure 13 us a cross-section showing the position
of the oil sand along a line from the SW. cor. sec. 27, T. 4 N., R. 4 \Y.
to a point a short distance south of the center of sec. 11, T. 4 X.. R. 4 W.
Had the outcrops been as numerous and as closely spaced as are the oil wells
in secs. 9, 10, 15, and 16, T. 4 N., R. 4 W. (Lamoine), the existence of
the terrace would have been revealed in 1912. The beds at the top of the
dome lie about 70 feet higher than on the terrace. No similar flat has thus
far been disclosed by drilling in other parts of the Colmar dome. The beds
dip away from the terrace in all directions except southwest.

CONDITIONS GOVERNING ACCUMULATION IN THE

COLMAR FIELD

The accumulation of oil in the Colmar field, with the exception of
Roberts No. 1 well mentioned later, is confined to the terrace on the north¬
east side of the dome. Most of the wells on the terrace reach the sand
85 to 95 feet above sea level. Griggsby No. 1 and Collins No. 1 located on
the crest of the dome produced only a show of oil at elevations of 167
and 151 respectively; whereas Roberts No. 1, two miles west of the
former wells had an initial daily production of 45 barrels from the Hoing
sand at an elevation of 163 feet above sea level. However, the latter well
is surrounded by dry holes and its production has declined rapidly to a few
barrels.

The striking differences in elevation between the oil in Roberts No. 1
and in the main field seem to be the result of (1) the nature of the oil¬
bearing bed and (2) the erratic position of the salt water. The second
feature is probably due in large measure to the first.

Oil-bearing Bed

In the main field the oil sand has an average thickness of 14 feet. It
ranges from 5 feet to more than 30 feet but in its greater thicknesses certain
horizons are more productive than others. Outside of the producing field,
many wells show no porous bed capable of holding oil; after passing
through the “second lime” the drill penetrates blue shale which probably
is the top of the Maquoketa shale.

THE COLMAR OIL FIELD

The oil sand exists in lenses and is surrounded completely by im-
previons beds, consequently it is natural for oil or salt water or both to exist
in separated areas at different altitudes with barren areas between.

Collins No. 1 and Griggsby No. 1 wells produced only a show of ('til
and no salt water, but practically no porous beds were found at the base of
the Hamilton limestone; whereas in Roberts No. 1, two miles west, 20 feet
of porous beds are reported under the “second lime,” and the oil is found
in the upper 10 feet. A short distance down dip from Roberts No. 1
these same porous beds are saturated with salt water.

Erratic Position of Salt Water

Salt water is found on the terrace from 10 to 15 feet below the top
of the sand. A. N. Wear Nos. 2, 4, and 6 and many of the wells on the
Thomas McFadden leases yielded salt water the first day and considerable
oil thereafter. Most of the wells lower down the dip in the vicinity of the
terrace contain salt water if the sand is present. South and west of the
terrace and in the higher part of the dome salt water fills the sands in the
vicinity of Roberts No. 1 well 40 to 70 feet higher than the salt water in
the terrace.

It is believed that the difference in elevation may be explained by the
fact that the sand exists in two separated areas and that between the two
the relatively non-porous limestone directly overlies the Maquoketa shale
and the general result is an area of impervious strata separating two
distinct lenses of porous, oil- and water-bearing beds. The conditions
influencing accumulation, therefore, act independently in the two separated
areas.

It is believed that a small lens of oil sand exists in the vicinity of
Roberts No. 1. Sometime after it had been covered by the overlying
formations, oil and salt water, probably from the Trenton limestone below,
migrated upward through the Maquoketa shale and found lodgment in
the porous sands. As long as the beds lay flat, there was probably no
definite rearrangement of the oil and salt water; but after the “Coal
Measures” were deposited, folding began which finally resulted in the
formation of the Colmar dome, the Lamoine terrace, and the other struc¬
tural features of the region.

Rearrangement began immediately, the final position of the oil depend¬
ing on the proportion of oil and water in the porous material (see figure
13 and discussion). That the lens of oil-bearing sand at the Roberts wells
is small is evidenced by the fact that the production of No. 1 has rapidly
decreased from 45 barrels per day to only a few barrels, and there seems
to be little hope of opening up a large production in the immediate
vicinity.

OIL INVESTIGATIONS

The general mechanics of accumulation in the producing terrace were
the same as those outlined above. The larger amount of oil in the terrace
is due probably to the fact that the mass of oil sand of which that on the
terrace is only a part, must be very large, and after the folding of the beds
took place the terrace, being the highest part of the lens, received all of
the oil by virtue of the difference in specific gravity between oil and salt
water, and the high degree of saturation of the sands.

ORIGIN OF THE OIL

No quantitative analysis of the organic material in the beds of western
Illinois are available to furnish a basis for assigning the origin of the oil
to any single formation. However, field examination in that part of the
State has emphasized the oily character of the Trenton. The odor of
petroleum is distinctly noticeable at most places on the outcrop and recent
drilling in Schuyler County has disclosed the same characteristics. In many
places the Trenton is composed largely of shells which give evidence of
the enormous amount of organic matter originally in the formation.

The “sweet” nature of the oil as mentioned in Extract from Bull. 23
has been a puzzling feature, since it is closely associated with limestones
which generally produce the “sulphur” or “sour” oils. However, if the
oil originated in the Trenton and finally found its way upward through
the Maquoketa shales into the Niagaran, the sulphur would have been
removed by filtration through the shale and “sweet” oil would result.
Further work is necessary before the origin of the oil can be definitely
assigned to the proper formation.

EXTENSION OF COLMAR FIELD

Up to date, practically the entire production has been from sec. 9, 10,
15, and 16, T. 4 N., R. 4 W. (Lamoine). Hartsook No. 1, NW. 34 SE. 34
sec. 14 contained no sand, but the bottom of the “second lime” which
marks the top of the normal oil sand lies 90 feet above sea level or at the
same elevation as the sand on the terrace one-half mile west. If the sand
is present in any part of the SW. 34 sec. 14, it should contain oil. A good
well has now been brought in by the Ohio Oil Co. in the SE. 34 NW. 34
sec. 14, about one-half mile east of the McFadden wells, and there is every
reason to believe that much of the area inside of the 90-foot contour in
sec. 14 as shown on Plate III will prove to be productive.

The territory south and west of Colmar between the Bott well in the
SW. 34 sec. 1, T. 4 N., R. 5 W. and the Roberts wells in sec. 24 of the
same township has not been sufficiently prospected. Wells should be drilled
in the S. 34 sec. 7 and the N. 34 sec. 18, T. 4 N., R. 4 W.; also in the S. 34
sec. 12 and the N. 34 sec. 13, T. 4 N., R. 5 W. The sand was not present
in the Bott v r ell, but that fact does not condemn the territory mentioned.

SURVEYED IN COOPERATION
U. S. GEOLOGICAL SURVE
GEORGE OTIS SMITH, DIREC

IS STATE GEOLOGICAL SURVEY

DUNNE, T. C. CHAMBERLIN, E. J. JAMES. COMMISSIONERS
FRANK W. DE WOLF. DIRECTOR

QA°45' ' TTTT3

ILLINOIS STATE G

GOVERNOR E. F. DUNNE, T. C
FRANK

BULLETIN NO. 31, PLATE III

Public roads

Number* refer to elevation of surface above sea level
■***•’ Private roads

,‘"\f Approximate outcrop of Murpliysborn (No. a) cool

^ Shipping cool mine

X Local coal mine

^ Stone quarry

Clay pit

->■■■ _ <t~. - —

COLCHESTER QUADRANGI

62^0 J Contour.. allowing elevation of Murphyaboro (No. a) coal bed above i

^*) J Sume with uncertainty, coal III greater part removed by croiion

ety

Contour* showing elevation of MurphyHboro (No. a) coal bed before remova
' ^ J by erosion. Contour Interval jo feet

Q'*' Contours on top lining sand

Structure Contour* on the Colchester (No. 2) Coal

by Henry Hind*

(U. H. Geological Surrey)

1012

Structure Contours on Hoing Oil Sami

by Wm. C. Mora*

1015

THE COLMAR OIL FIELD

when the possibility of a terrace and the lenticular nature of the sand are
considered.

SUMMARY

Consideration of the information thus far developed in the Colmar oil
field and surrounding territory leads to the following conclusions:

1. The oil sand and the overlying beds are essentially parallel to one
another, and the determination of the “lay” of the oil sand in
advance of drilling by leveling to outcropping beds is practicable.

2. The oil-bearing bed is a porous sandstone lying above the
Maquoketa shale and at the base of the “second lime.” A show
of oil is noted here and there in what is probably the base of the
Niagaran dolomite, but no important accumulation is known
except in the sand.

3. The Maquoketa shale existed as land surface before the over-
lying beds were deposited and the sands that now contain the oil
probably accumulated in the lower areas before or at the beginning
of the submergence which caused the deposition of the Niagaran.
Afterward the latter formation was exposed to erosion at the
surface and in many places streams cut their channels not only
down through the Niagaran but also into the Maquoketa shale;
thereby removing any sand that may have existed at the base of
the Niagaran. The Hoing sand, therefore, exists as separated
lenses, the presence or absence of which at any given point cannot
be predicted in advance of drilling.

4. The accumulation of petroleum depends (1) on the geological
structure of each particular lens, i. e., the dip and strike of the
beds and (2) the relative saturation of a given lens by oil and
salt water.

5. The accumulation east of Colmar is on a flat or terrace in the
sand, on the northeast side of a pronounced elongate dome. The
crest of the dome is barren of oil except at the west end where
a short-lived well was drilled, and later was surrounded by wells
producing salt water, 70 feet higher than the oil in the main
Colmar field.

6. The lens of which the producing sand on the terrace is a part is
much larger than the one tapped by Roberts No. 1 at the west
end of the dome, the amount of oil in any given lens being
approximately proportional to the area and thickness of the lens.

7. The sand of the producing field is entirely separated from that at
the Roberts wells, consequently there is no relation between the
altitude of the oil and salt water at the two places.

OIL INVESTIGATIONS

8. Some extension of the field is to be expected around the edges of
the present producing area, especially in the SW. and the
S. Y 2 of the NW. Y sec. 14 as mentioned under “Extension of the
Colmar field'’. The possibility of favorable conditions west and
south of Colmar between the Roberts and the Bott wells, is
recognized (see text).

9. The oil may have originated in the Trenton limestone and migrated
upward through the Maquoketa shales to the porous sand. Its
“sweet" character may be due to filtration through almost 200 feet
of shale which would have extracted from the oil most of its
sulphur content.

Generalised section of rocks in Colmar oil field and surrounding territory

System

Series

Drillers’

Interpretation

Formation

Character

Thickness

Alluvium—mostly clay and

Feet

sand; confined to the pres-

ent valleys.

Variable

Loess—fine material between

clay and sand, unconsoli-

dated, thicker along bluffs

of larger streams, weathers

into vertical cliffs; most

conspicuous along west

bluffs of Illinois River.

0-75

Drift — mixed clay, sand,

Average-25

gravel, and bowlders, near

In filled val-

surface on uplands.

leys-lOOH -

Generalized section of rocks in Colmar oil field and surrounding territory

System

•—

s
o
>
c J

C/5

’>

■o

Series

u 2

J? >

Drillers’

Interpretation

Formation

Character

Alluvium—mostly clay and
sand; confined to the pres¬
ent valleys.

Loess—fine material between
clay and sand, unconsoli¬
dated, thicker along bluffs
of larger streams, weathers
into vertical cliffs; most
conspicuous along west
bluffs of Illinois River.

Drift — mixed clay, sand,
gravel, and bowlders, near
surface on uplands.

•u

Carbondale

Pottsville

Unconformity

St. Louis

Unconformity

Salem

Unconformity

Warsaw

Keokuk

Burlington

Kinderhook

Unconformity

Hamilton

Unconformity

Hoing
oil sand

Unconformity

Richmond

(Maquoketa)

Unconformity

Kimmswick-

Plattin

(Trenton)

St. Peter

Principal coal-bearing for¬
mation of Illinois. Shales
and sandstones containing
thin beds of limestone, clay
and coal. Exposed from
coal No. 2 which is the
base to a few feet above
coal No. 5, a thickness of
130-140 feet. Coal No. 5
exists in a small area north
of Rushville and Pleasant
View. Entire formation
eroded in places.

Includes beds from base of
coal No. 2 to Mississippian
limestones. Sandstone and
shale, and some limestone,
clay, and thin coal. Lies
on old eroded land surface
and is variable in thickness.

Thickness

Feet

Variable

0-75

Average-25
In filled val-
levs-100+

Limestone, brecciated, gen¬
erally blue but weathers
yellow in places; contains
scattered corals. Its hard¬
ness enables it to withstand
erosion; blocks ring when
struck with hammer.

Impure limestones having
yellow tint. In many places
difficult to distinguish from
limy sandstone; whereas at
other exposures the amount
of shale increases and the
formation is a mixture of
limy shales, limy sandstone,
and very impure limestone.
Very difficult to distinguish
contact with underlying
Warsaw. Fossils scarce.
Dull sound when stmek
with hammer.

Thin-bedded, impure lime¬
stone and shales, some of
which are very fossilifer-
ous. In some places con¬
siderable blue clay shale is
present. Bryozoa abundant
in shales; Archimedes in
limestones.

Gray crystalline limestone,
very fossiliferous, becoming
shaly toward top. Geodes
abundant.

Limestone, generally cherty;
not exposed in region.

Shale, bluish gray, limy in
places.

Shale, light to dark; con¬
tains many spores of Spor-
angites, a minute reddish
fossil.

Limestone, gray, small
amount sand, and some
small crystals of pyrite.
Usually not magnesian.

Limestone, gray, crystalline,
magnesian. Exists in sep¬
arate lenticular masses;
where it is not present
Hamilton rests on Maquo¬
keta shale. Show of oil in
places near base.

Sandstone, quartzitic; grains
well rounded. In lenses
with no connection. Prob¬
ably accumulated in depres¬
sions on Maquoketa sur¬
face. The producing bed
of Colmar field and sur¬
rounding territory.

0-140+

0-140

Shales, bluish green; bluish
mud when drilled.

Limestone, gray, white, or
brown. Very crystalline in
places. Odor of oil not
unusual. Not magnesian in
Colmar field and area to
south.

Sandstone; generally satu¬
rated with highly mineral¬
ized water.

0-30+

30 ±

30+

100 ±

15-30

0-20

0-25
(Average in
Colmar field
14)

180-200

300-400

145-225

recorded

Table 2. — List of wells in Colchester and Macomb quadrangles

THE COLMAR OIL FIELD

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Elevations obtained by hand level.

Table 2 .—Continued

OIL INVESTIGATIONS

( f)

<L)

3DEJ Jllg

c/3

M - —<

-u 'O
03 CM

CL)

o Jn

£ <u
O d

| r- 1

CO CO

i V

t-*

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>>22
rt ^

^ t/)
1— O

a u
^ u

os re

£ ~
4-. LO

(•siqq) uop.
o.ipojd [Bipu]

Dry

D ry

Prod

Total

depth

• •

603

638

645

1050

678

630

519

449

452

453

456

457

pajEjjauad
pues JO
ssauqatqj.

ship

ownsh

wnship

wnshi

Elevation
of top
of sand

Town

-18

ter T

62?

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-44 (?)

e To

Depth to
sand

ethel

612

437

olehes

540

ndustr

659

amoin

468

504

439

• •

434

424

429

PQ O M

CM <0
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r-t (M

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CM

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£ X rt
£ u _£
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>4.5

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2 7. m
i be

r £

a ^ CP P^H 'tn K

” 1 3 :1 <«*

^ £ V-; £ d ffi ^

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co O

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[H 3 A\JO-OjSjdEJ\[

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T— H

—

jajjBnh puB

•o^j uoipag

r-H

CN)

£ £

Table 2.— Continued

THE COLMAR OIL FIELD

■X

4->

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u~)

ct5

4->

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C/5

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v—H

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(•siqq) uop.
onpojd jbi jiuj

T3 "U 03 'll) 03 03 03

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Vi Vi Vh Vh Vi Vi Vi

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HOHOOTfO'HOOOM-CMNfO'MOiOCMfO
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lololololololololololololololololololo

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a <

Name of Company

Ohio Oil Co.

Do.

J. E. Urschel & Co.
Do.

Do.

Snowden Bros. & Co.

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jajjBnb puB

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-B—31

o o o o
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Q Q C Q Q Q

W £

53 co

Table 2 .—Continued

OIL INVESTIGATIONS

C/2

(•S[qq) uotj

-onpoad [Bijiuj

■'T

C/3 w J/3

*o3

4 -»

C/3

C/J C/3 l-J t/3 C/3 j-* C/3

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571

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Table 2. — Continued

THE COLMAR OIL FIELD

^ 1 "

4- »

4 — »

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i_i

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C 3

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C/3 CC

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(•S[qq) uoxj
-onpoad ppm]

1—4

T —<

Tt"

CO'

^ Q

t-H

t—H

r—4

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japEnb puE

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Table 2 .—Continued

</>

(•siqq) uop
-onpeuu xt* 14111 j

p3}B.I}3U3d

puns jo

ssouqoiqx

M C O

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v—

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OIL INVESTIGATIONS

<3J

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- c c ^- t t -r t x -t r c c c is m ci n ci ci ^ t *t
VO tJ- ^ M" 'cF rj- tJ- -rj- tF tF M" r T vo M" rj- Tf Tl" ^ Tf Tt - ^ M"

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CM vo 00 CM O ’— 1 "rt" '■t vo O vo cm vo sO co M" CM «— 1 On CM C CM 00 >—' OC
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OCMN-i'-i'-iMONfOiOONCONMf'lNvCaXXXNNNX
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Table 2. — Continued

THE COLMAR OIL FIELD

c n
AA
Vi
rt

(•S[qq) uoij

-d

-o’

-onpoad ibijxu]

1X1

r—H

U-

J-H

r-H

r—H

IX)

T—H

t-H

r-H

r—H

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o &

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H-S

M-

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pajBjjauad

t-H

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pUBS JO

ssouqoiqjL

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P P

p p p p p

PPPPPPPQQQ

c n

[[3MJO-OJVjdBJ\[

asjJBnb puB
•ojq uoijoog

OIL INVESTIGATIONS

h-)

(•siqq) uoij.
-onpoad iBtjiu

pajEijouad
. puES jo
ssaujptqj.

.2 a 2

| S S

•8*3-

r .,1 O

UOUEAOp

# 30EJJtng

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3-0

cm r:

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to T3 ~
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£ 8 g

Q O

2 O 2=

CO £

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Cu CL Cl

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* * *

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Table 2.— Continued

THE COLMAR OIL FIELD

c/l

t-l

(* s iqq) u °q

onpoad jbtjiu]

o a

r V

H -a

p3}Ei}3U3d
PUBS JO

ssoujpiqx

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v 03

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T 3

<—

c 3

M-i

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jojaBiib puB
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c/3

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£

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if)

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CO C/I CO

CO ^

O 2 oil

0O Qs,

THE ALLENDALE OIL FIELD

By John L. Rich

(In cooperation with the U. S. Geological Survey)

OUTLINE

PAGE

Introduction . 59

Area and location.•. 59

Acknowledgments . 59

History. 59

Topography . 61

Stratigraphy .•. 61

Unconsolidated rocks. 61

Consolidated rocks. 63

Pennsylvanian series. 63

Mississippian series. 64

Stratigraphic position of oil sand.•.. 64

Characteristics of the oil sand. 64

Structure . 65

Structural features of the area. 65

Production in relation to structure. 66

Areas favorable for further drilling. 67

Possibility of further development by deeper drilling. 67

( 57 )

ILLUSTRATIONS

PLATE

IV Map of Allendale oil field showing geologic structure of oil sand. 64

V Cross-section showing position of oil sand. 66

VI Map showing initial and later production of Allendale wells. 68

FIGURE PAGE

14. Map showing location of Allendale field. 60

15. Graphic table showing wells completed by months and number productive.... 62

TABLES

FIGURE PAGE

3. Table showing monthly development of Allendale field. 61

( 58 )

INTRODUCTION
Area and Location

In August, 1912, a successful well opened up the Allendale oil field
in T. 1 N., R. 12 W., Wabash County, Illinois. The field at present is
small, about one and one-half miles long by three-fourths of a mile wide
lying in parts of secs. 3, 4, 9, 10, and 16. The principal producing area
lies in secs. 4 and 9.

The Allendale field lies isolated about 8 miles southwest of the newly
developed continuation of the Lawrence County field at St. Francisville.
It is developed on a minor north-south fold or dome lying upon the western
flanks of the larger fold which gives rise to the main Crawford and Law¬
rence county fields. Allendale, a small village on the Cleveland, Cincinnati,
Chicago and St. Louis Railway, lies about 2 miles southeast of the field and
is the nearest point of supply.

The purpose of the recent investigations of this field was to determine
the structure of the field, its relation to the nearby larger fields, and the
character and stratigraphic position of the producing sands, in order to
ascertain the possibility of further development of the field, and the location
of areas where future prospecting is most likely to be successful.

Acknowledgments

The preparation of this report has been greatly facilitated by the
kindly cooperation of the officials of the various oil companies operating in
the Allendale field. To Mr. J. K. Kerr, general superintendent, and to
Mr. Ora Fess, local field superintendent of the Ohio Oil Co.; to Mr. A. E.
Baldwin and Mr. M. A. Arvm of Snowden Bros. & Co.; and to Messrs.
Tyler Andrews and A. D. Smith of the Sian Oil Co. especial acknowledg¬
ment is due. Prof. T. E. Savage of the State Geological Survey gave
helpful consultation regarding questions of stratigraphy.

History

The first successful well in the Allendale field was drilled late in
July, 1912, on the farm of Adam Biehl in the NE. cor. SE. JJ, sec. 4.
This well having an initial production of 650 barrels proved to be one
of the best in the field and created great excitement at the time. A rush
followed, and within a few months many more wells had been completed.

The accompanying table presented graphically in figure 15, shows the
number of wells completed during each month since the opening of the
field and the number of these which were successful.

( 59 )

OIL INVESTIGATIONS

Fig. 14. Map showing location of Allendale oil field.

THE ALLENDALE

OIL FIELD

Table 3-

-Monthly development of Allendale field

Wells

Number of

Wells

Number of

Month

drilled

producers

Month

drilled

producers

1912-

-June .

. . 1

July .

.. 3

July .

. . 0

August ..

.. 3

August . .

. . 1

September

.. 0

September

.. 4

October ..

.. 2

October . .

.. 14

November

.. 2

November

.. 8

December

.. 1

December

.. 8

1914—January . .

.. 0

1913-

-January . .

.. 9

February .

.. 2

February .

.. 2

March . ..

.. 0

March . ..

.. 4

April . . . .

.. 0

April .

.. 1

Mav .

.. 2

Mav .

.. 4

Tune .

.. 2

Tune .

. 3

—

Total . .

.. 76

Percentage of total number productive.59

During the four months from October, 1912, to January, 1913,
inclusive, more than one-half the total number of wells in the field was
completed. As is indicated, a discouraging number of those completed
during November, December, and January were dry holes (see figure 15).
This was due to the fact that of the wells drilled during the months
named, a large proportion were put down around the outside of the produc¬
ing area for the purpose of testing the extent of the field. These unsuc¬
cessful wells showed clearly that the productive area would be small. Since
January, 1913, the number of wells drilled each month has steadily
decreased. Since February, 1913, it has never exceeded four, and since
August of that year it has averaged only about one a month. Since the
limits of the field have become fairly well known the proportion of success¬
ful wells has increased to about 60 per cent.

Topography

The Allendale field is located in a gently rolling area of slight relief
situated on the southwestern slope of a group of low hills about sixteen
square miles in extent, which rise somewhat less than 100 feet above
surrounding alluvial lands. Elevations range from 430 to 510 feet above
the sea, but all slopes are gentle and the valleys are broad and open. The
irregularities are nowhere sufficiently great to interfere with the hauling
of materials and supplies, or with the installation of the apparatus used in
pumping the wells.

STRATIGRAPHY
Unconsolidated Rocks

The bed rocks of the region are everywhere concealed by a mantle of
unconsolidated clays, sands, and gravels known as the glacial drift, and

OIL INVESTIGATIONS

Fig. 15. Graphic table showing wells completed by months and number productive.

THE ALLENDALE OIL FIELD

by fine wind-blown ‘‘loess”. This mantle, as revealed in the wells,
averages about 45 feet in thickness, but it varies from about 15 feet to
somewhat more than 100 feet. In general it is thinnest on the higher
ground and thickest in the valleys and on the broad flats which surround
the field. On the uplands it consists of yellowish, loess-like clay and
sand, with blue “hardpan” (glacial till) in places at the base. The top
portion of this yellow loam is loess, a fine dust which at an earlier period
was deposited by the winds.

Consolidated Rocks

Down to the greatest depths reached by the wells the underlying
rocks of the region belong to the two divisions of the Carboniferous sys¬
tem: the Pennsylvanian above, and the Mississippian below. About 1300
feet of the Pennsylvanian rocks has been encountered, but only the upper
part of the Mississippian series has been penetrated.

PENNSYLVANIAN SERIES

The Pennsylvanian rocks consist of a series of shales alternating with
sandstones and occasional thin lenses of limestone. The latter, however,
comprise only a relatively small part of the section. The sandstones and
shales occur in beds of varying thickness ranging from only a few feet
to 200 feet or more.

The Pennsylvanian series in this State is commonly separated into
three formations: the McLeansboro at the top, extending down to the top
of coal No. 6; the Carbondale, including the strata from the top of coal
No. 6 to the base of coal No. 2; and the Pottsville, extending from the latter
to the base of the Pennsylvanian series. From the records of the wells in
the Allendale field it is impossible to draw any sharp lines of distinction
between these three formations. The horizon of coal No. 6 may be
recognized in a general way at 500 to 600 feet below the surface, but
the horizon of the Murphysboro (No. 2) coal cannot be so definitely
distinguished.

The most noteworthy feature of the Pennsylvanian rocks is their
variability both horizontally and vertically. Lenses of sandstone more
than 50 feet thick in one well may be absent in nearby wells. In fact, so
great is the variability of these beds that no close correlations between
them can be made.

A few beds are fairly persistent and may be recognized in a large
proportion of the logs. In almost all the wells a water-bearing sandstone
is found at 100 to 200 feet below the surface. Another water-bearing
sand, occasionally appearing as two sands a short distance apart, is usually
found at about 600 feet. This, however, is not sufficiently persistent to
be recognizable in all the wells, nor sufficiently definite in its position

OIL INVESTIGATIONS

to serve as a basis for contouring. At the base of the Pennsylvanian series
is a massive white sandstone (Pottsville) which averages about 150 feet
in thickness and may be recognized in nearly every well. This, the most
easily identifiable bed in the whole series, is correlated with the Buchanan
sand of the Lawrence County field.

In addition to the sands, one or more beds of coal are recorded in
several of the logs. One of these coals, lying between 500 and 600 feet
below the surface, is thought to represent coal No. 6 (Herrin or Belleville).
However, the records are too few in number, and they lack sufficient
agreement to make this correlation certain.

MISSISSIPPI AN SERIES

Beneath the heavy sandstone at the base of the Pottsville lies a series
of thin limestones and shales with occasional thin beds of sandstone, the
latter increasing in thickness and importance toward the base of the
section penetrated by the wells. This is the Chester group. The exact
thickness of the Chester in the Allendale field is uncertain, but is at least
700 feet, since two wells on land of John H. Schafer and C. F. Adams
have penetrated Chester strata to that depth without having reached its
base. Several thin beds of red shale mark the lower part of the formation
in nearby fields. These were found in both of the deep wells mentioned;
in one at a depth between 1915 and 1950 feet; in the other between 1830
and 1910 feet, indicating that the bottoms of the wells at about 2000 feet
must be near the base of the Chester.

Stratigraphic Position of the Oil Sand

The producing sand in the Allendale field, commonly known as the
Biehl sand from the farm on which the oil was first struck, lies about
190 feet below the top of the Chester. This interval varies between 130
and 250 feet, probably on account of the uneven upper surface of the
Chester, which was irregularly eroded before the Pottsville formation was
deposited above it. From its stratigraphic position it appears that the
Biehl sand should be correlated with the Kirkwood sand of the Lawrence
County field.

No oil has been reported from any of the sands in the Pottsville,
or in the Chester below the general level of the Biehl sand. There is,
however, evidence that a few of the wells on the borders of the field
secure their oil from sands a few feet lower than the Biehl sand. Such
lower sands seem to be local lenses which carry the oil in places where
the regular sand is not present.

Characteristics of the Oil Sand

The oil appears to have accumulated in a single bed of sandstone
in all parts of the field except at the few wells mentioned immediately

;

SURVEYED IN COOPERATION WITH
V. S. GEOLOGICAL SURVEY
GEORGE OTIS SMITH, DIRECTOR

ILLINOIS STATE GEOLOGICAL SURVEY

GOVERNOR E. F. DUNNE, T. C. CHAMBERLIN, E T. JAMES, COMMISSIONERS
FRANK W. DE WOLF, DIRECTOR

BULLETIN NO. 31, PLATE IV

IY..L Andrews

D. S.Ravatt

C.Hershey

2 Oil well with farm
• number ami surface
455 elevation.

Contour showing pos-
I ition of oil sand
/above a plane 1S00
* feet below sea level,
o Contour interval 10
O feet.

Map of Allendale oil field showing structure contours on producing oil sand
by John L. Rich

THE ALLENDALE OIL FIELD

above where, because of the irregularity in depth at which the oil was
reported, it appears that it must be in beds or lenses slightly lower in
the series. The principal wells showing this discrepancy are W. II. Arm¬
strong No. 3 and C. Smith No. 9, at the southern end of the field.

In most of the wells the oil sand varies from 20 to 30 feet in thickness,
but a maximum of at least 40 feet is known. A marked local thinning of
the sand was disclosed in the wells near the NE. ^4 NW. J4 sec. 9.

The sand is described as brown or light brown, the color probably
being due merely to oil stain. It is usually soft, though in a few wells
it is reported as hard. Wells in sand of the latter type yielded only small
quantities of oil, even though located where the structure is favorable.

In most of the field the oil sand is overlain by a bed of limestone 20
to 30 feet thick; however, in McMillen Nos. 6, 7, and 8, in the NW. J4
SE. 14 sec. 9, shale forms the cap rock.

STRUCTURE

Structural Features of the Area

The structure or the “lay" of the oil sand is represented on the
map (Plate IV) by means of contours drawn on the top of the Biehl
sand. These contours, which are drawn for every 10 feet represent the
elevation of the top of the sand above a plane 1500 feet below sea level.
Each contour connects points on this sand having the same elevation
above this datum plane.

The depth of the top of the sand below the surface of the ground in
each well may be found by subtracting the number of the contour passing
through the well from 1500 and then adding the elevation of the well
above sea level. Thus if a certain well is on the 490-foot contour and the
elevation of its mouth is 468 feet, then 1500—490=-= 1010, 1010—(-468
gives 1478 as the depth of the top of the oil sand below the surface of
the ground.

The map shows that the Allendale field is located on the top of a
distinct arch or dome, the main axis of which extends in a north and south
direction, and that from the top of this elevated area the rocks dip away
in all directions. Closer examination reveals certain minor features of
the structure of the arch which deserve special mention since they play
a large part in determining the detailed distribution of the oil.

Along the eastern side of the arch, and forming its crest, is a prom¬
inent anticline, broad in the middle and narrowing at both ends, which
extends north and south through the eastern parts of secs. 4 and 9. The
western limit of the higher parts of the arch is marked by a smaller, less
distinct fold extending from near the center of sec. 9 northward to the

John Prout well in the eastern part of the SE. Y\ SW. Ct sec. 4. Be-
5—B—31

OIL INVESTIGATIONS

tween these two bounding ridges is a broad, flat area diversified by a
few small hollows or synclines.

The broadest portion of the eastern anticline lies just west of McFar¬
land School in the NE. corner of sec. 9 and the SE. corner of sec. 4.
From here the anticline narrows rapidly toward the north, and at the
J. Biehl well in the NE. Fi SE. Ft sec. 4 it is a sharp ridge. To the south
the crest becomes narrow in the SE. Ft NE. Ft sec. 9, but farther south
on the Caroline Smith farm, it widens into a small, elongate dome which
for convenience may be designated the Caroline Smith dome.

The secondary anticline in the western part of the field is not well
developed, though it gains sufficient prominence to appear upon the con¬
tour map and to affect materially the production of the wells located in
its vicinity. Its top is about 25 feet lower than that of the eastern anti¬
cline. As already indicated, it marks the western limit of the elevated
area. On its western flanks the beds dip steeply to the west.

In the southern part of the field there appears to be a minor ridge
extending through the W. H. Armstrong farm and northward to include
wells No. 7 and No. 8 on the McMillen farm. This elevated area is
separated from the Caroline Smith dome by a shallow trough or syncline
(see Plate Y).

Another structural feature which deserves mention is the small ter¬
race in the western part of the SE. Ft sec. 4 upon which are located the
four wells Wrn. Wolf, H. Jones No. 1, and Elisha Litherland Nos. 1 and
2. This is a relatively inconspicuous feature, yet its effect is very evident
in the production records of the wells located upon it.

Production Records in Relation to Structure

The accompanying map (Plate YI) shows the initial and the present
(July 1, 1914) production of each of the wells from which data could
be secured. A study of these records in relation to structure yields
strong confirmation of the theory that oil tends to accumulate at or near
the crests of anticlines or domes or on local flattenings (terraces) in
dipping rocks. From the map it is evident that only the wells situated
upon the crest or high on the sides of the elevated tract were productive.
The most conspicuous features brought out by this map are: (1) the uni¬
formly high initial yield of the wells situated upon the higher parts of the
main anticline and of the Caroline Smith dome; (2) the good yields of the
four wells situated upon the Jones-Prout-Litherland terrace; 1 (3) the
relatively high yields of the wells (Edwin Smith, Nos. 1 and 3, and H.
Mulinax No. 1) situated on the crest of the western anticline; and
(4) the relatively low yields of wells situated on local depressions.

1 A letter dated Dee. 3, 1914 states that wells J. B. Litherland Nos. 1 and 2 have declined
considerably within the past two months.

LLINOIS STATE GEOLOGICAL SURVEY

ILLINOIS STATE GEOLOGICAL SURVEY

BULLETIN NO. 31, PLATE V

1 Della V Wright No.2 Wabash Twp..Sec.9,T.1 N.R.12 W.

~ Della V.Wright No.1 Wabash Twp.,Sec.9.T. 1 N.R.12 W.

3 McMillen Farm No.6 S.E. 1/4 N.E. 1/4 , Sec.9,T. 1 N..R.12W.

4 Caroline Smith No.2 Wabash Twp., Sec.9,T.1 N..R.12 W.

O Caroline Smith No.1 Wabash Twp.,Sec.9,T.1 N.R.12 W.

6 H.Buchanan No.1 N.W.Cor..S.W.1/4.Sec.10.Wabash Twp.

East-west cross-9ection through Allendale field showing position of oil sand

The thick limestones shown in the lower part of the coal-bearing rocks in 3 and
5 were probably incorrectly reported by the driller. They should probably be shown
as sandstone or sandy shale.

THE ALLENDALE OIL FIELD

In some wells the production reported is much smaller than would
be expected from the structure; for instance, Caroline Smith No. 1 started
with 480 barrels per day; whereas No. 11, apparently as favorably located,
gave an initial output of only 65 barrels. The decrease is better understood
when the date of drilling is considered. Well No. 1 was completed in Sept.
1912; No. 11 in August,. 1913. In the meantime the pressure upon the
oil in the pool must have been notably decreased by the drawing off of
oil to No. 1 and several other wells nearby, most of them at lower levels.
Similarly, Ed. Smith Nos. 1 and 4, the one apparently as favorably situated
as the other, show a marked difference in initial production, and here
again the earlier well gave the higher yield.

There can be little doubt that variations in the porosity of the sands
account for some of the discrepancies observed. Certain of the records
of the wells in the Caroline Smith dome seem to show that the oil
sand was not saturated entirely to the top. A study of this feature in
connection with the structure leads to the belief that the phenomenon
is to be explained by variations in the porosity of the sand, the top portion
in some of the wells being too compact to permit the accumulation of oil.

Gas in small quantities was reported from Caroline Smith Nos. 1, 2,
4, and 8, but no definite relation between the occurrence of the gas and
the structure or other features could be discerned.

AREAS FAVORABLE FOR FURTHER DRILLING

On the map (Plate VI) the areas in which the structure seems most
favorable for further drilling are indicated by cross-line shading. For the
most part these areas lie within the limits of the field as already outlined.
The area indicated in the NE. Rj NW. Rj sec. 9 seems worthy of testing
by a hole placed about one location south of the road and a short distance
west of north of H. Mulinax No. 1. One or more wells in the McMillen
tract ought to pay. A considerable area of favorable territory is included
in the Ed Smith and Jacob Smith farms. This territory is not likely
to furnish high yields, but a moderate production may be expected. An¬
other area which seems favorable includes parts of the Jo. Jordan. Jacob
Smith and Adam Biehl farms.

POSSIBILITY OF FURTHER DEVELOPMENT BY DEEPER

DRILLING

Considering the success of the deep wells in the McClosky sand in the
vicinity of St. Francisville, it would seem worth while to test this sand
in the Allendale field. Thus far no wells within the producing area of
the field have gone sufficiently deep to reach the McClosky. Two wells—
the John H. Schafer and the C. F. Adams—have penetrated to a depth

OIL INVESTIGATIONS

somewhat over 2000 feet, but appear not to have reached the McClosky.
Besides, these wells are not located upon the higher structures, so that,
even had they gone deeper, it is doubtful if they would have been suc¬
cessful.

The Chester is thicker in this region than in the Lawrence County
field; consequently, the depth to the McClosky is greater. It is thought
that the McClosky should be reached at about 600 feet below the Biehl
sand, which would mean for most of the field a depth of 2100 to 2200
feet below the surface, though it is possible that the depth might be
slightly greater.

Should a successful well be drilled to the McClosky sand, further
development should proceed cautiously upon the higher parts of the struc¬
ture as indicated on the map (Plate AT). There are no indications that
wildcatting outside this area would meet with success.

ILLINOIS STATE GEOLOGICAL SURVEY

BULLETIN NO. 31, PLATE VI

Oil well with initial production
(bbls.) shown in black and lat¬
er production shown in red

Dry hole

Coatour showing position of oil sand
above a plane 1500 feet below sea
level

Areas favorable for drilling

Arrows point to wells for
which aggregate produc¬
tion is given

0 1/4

1. 1

Scale

1/2

3/4

Mile

Map showing initial and later production of Allendale wells

ANTICLINAL STRUCTURE IN RANDOLPH

COUNTY

By Stuart Weller

(In cooperation with the U. S. Geological Survey)

The association of petroleum with anticlinal structure in the rock
strata has been so well established that the recognition of such folds is
of prime importance to the oil driller. During the detailed mapping of
the Chester quadrangle comprising a portion of Randolph County a small
anticline which may be productive of oil if properly drilled has been
recognized. This anticline is just north of Bremen about eight miles
northeast of Chester. The axis of the anticline, as located on the accom¬
panying map, extends N. 70°E. and very nearly intersects the corner be¬
tween secs. 21, 22, 27, and 28, T. 6 S., R. 6 W. On its northern limb
the rocks dip at angles from 7 to 10 degrees; whereas the dip of the
southern limb is about 2 degrees. The folding of the rock has not been
detected west of Little Marys River and the dipping strata are best
exposed in the east tributaries of this stream. The extension of the fold
to the northeast has not been determined because the detailed mapping
has not been extended in that direction, but it is altogether probable that
the structure becomes more pronounced.

The rock formations involved in the Bremen anticline are of the
Chester group and the base of the Pennsylvanian series. The entire
thickness of the Chester group, as developed in Randolph County, is
present in this area. In the eastern Illinois field much of the oil is pro¬
duced from the sands in the lower portion of the Chester group, probably
the Renault formation, which would be penetrated at Bremen at a depth
of 500 to 600 feet. The comparatively shallow depth of the possible oil
sands in the Bremen anticline makes prospecting in the territory desirable.

( 69 )

OIL INVESTIGATIONS

Fig. 16. Map showing location of Bremen anticline.

OIL AND GAS IN THE GILLESPIE AND MX.
OLIVE QUADRANGLES, ILLINOIS

By Wallace Lee

(IJ. S. Geological Survey in cooperation with the Illinois State Geological Survey)

OUTLINE

PAGE

Introduction.. 73

Acknowledgments . 73

Area treated in report. 73

Drainage and topography. 74

Stratigraphy . 74

Cambrian and Ordovician rocks. 74

Silurian and Devonian rocks. 75

Mississippian series.•. 75

Pennsylvanian series. 76

General statement. 76

Pottsville formation. 77

Carbondale formation. 77

McLeansboro formation. 81

Quaternary deposits. 85

Structure . 85

Structure contours.•. 85

Structure of the Gillespie-Mt. Olive quadrangles. 86

Litchfield oil and gas field. 87

Carlinville oil and gas field. 91

General relations of oil to structure and stratigraphy. 99

Anticlinal areas favorable to retention of oil and gas. 101

Staunton dome.•. i . 101

Spanish Needle Creek dome. 102

South Litchfield dome. 103

Butler anticline. 103

Macoupin dome.•.•. 104

Sorento anticline.•. 105

Other possible areas. 105

Local presence of gas. 105

“Kerosene” spring. 106

( 71 )

ILLUSTRATIONS

PLATE PAGE

VII Graphic sections of Litchfield wells. 88

VIII Graphic sections of Carlinville wells. 92

IX Map showing topography and geologic structure of the Gillespie quadrangle 100
X Map showing topography and geologic structure of the Mt. Olive quadrangle 102

FIGURE

17. Map showing location of wells in Litchfield pool, and order of arrangement

of logs in Plate VII. 89

18. Map showing structure contours on Herrin (No. 6) coal and on top of oil

sand in Carlinville pool. 92

19. Map showing location of wells in Carlinville pool and order of arrangement

of wells in Plate VIII. 96

20. Ideal section through a dome showing sand-filled channels in cross-section.

points of accumulation of oil and gas, and direction of migration. 98

( 72 )

INTRODUCTION

Acknowledgments

The area of which this report treats lies in Macoupin, Montgomery,
and Bond counties and was included in the region recently discussed by
R. S. Blatchley 1 . However, Mr. Blatchley’s report was somewhat pre¬
liminary in nature. Since it was published, the work on which the present
report is based was undertaken by the State Survey in cooperation with
the United States Geological Survey under considerably more advantageous
circumstances. Topographic maps prepared under the same cooperative
agreement made it possible to determine altitudes of the tops of wells
much more accurately. A considerable number of new drill records have
also been secured, and the rock outcrops have been examined, such data
giving a much greater number of points than was available for the de¬
termination of the structure of the rocks at the time Bulletin 28 was
written. The present report though having these advantages over previous
work still lacks detail in parts of the area where neither outcrops nor well
logs are available.

The writer wishes to acknowledge with thanks the assistance given
by the Superior Coal Company in the persons of Messrs. John Reese and
John Ross of Gillespie; by Mr. A. W. Crawford of Hillsboro, Mr. E. J.
Hurd of Chicago, Messrs. David Davis and H. Hood of Litchfield, Mr.
Frank Brown of Hillsboro and Messrs. E. A. Ibbetson and T. A. Rinaker
of Carlinville, and many others to whose generous cooperation in allowing
the use of private information and to whose public-spirited attitude toward
the work, the writer owes to a considerable extent the value of this report.

Area Treated in Report

The area examined comprises the Gillespie and Mt. Olive quad¬
rangles mapped topographically by the United States Geological Survey
in cooperation with the Illinois State Geological Survey, an area 27 miles
from east to west and 17 miles from north to south. It includes the
southeastern part of Macoupin County, the southwestern part of Mont¬
gomery, and a small area in the northwestern corner of Bond County.
The area extends from a point two miles south of Carlinville to Staunton
and Sorento on the south, and from Hillsboro on the eastern margin to
Plainview and Bunker Hill near the western edge. The district includes
also the towns of Litchfield, Mt. Olive, Gillespie, and Benld and the villages
of Dorchester, Hornsby, Butler, Walshville, and Panama.

1 Blatchley, R. S., Oil and gas in Bond, Macoupin, and Montgomery counties: Ill. Geol.
Survey, Bull. 28, 1914.

( 73 )

OIL INVESTIGATIONS

Drainage and Topography

Macoupin Creek, flowing in a general westerly direction into Illinois
River, drains the northwestern corner of the area. Shoal Creek with its
tributaries drains the eastern half of the district and flows south into
Kaskaskia River. The southwestern quarter is drained by the head waters
of Wood River and Cahokia Creek, which flow southwest and empty
directly into Mississippi River. The forked divide between these creeks
is a broad, flat, undissected prairie rising imperceptibly toward the
northeast. Near Bunker Hill the altitude is 660 feet above sea level,
whereas 20 miles distant at Litchfield, it is only 20 feet greater. East
of Shoal Creek the prairie surface is broken by morainic hills left by
a continental glacier. Several of these hills rise more than 75 feet above
the general level. The valleys are incised in the flat prairie surface and
have rather steep confining slopes. The major streams have cut to a
depth of 75 to 85 feet below the upland prairie level.

STRATIGRAPHY

The rocks of southern Illinois consist of nearly horizontal layers
of shale, sandstone, limestone, and coal which will be described in order
from the lowest and oldest to the highest and youngest. In southern Illi¬
nois the older rocks do not outcrop at the surface and are known only
from drill holes and from outcrops in adjoining states. They form a
series of sandstone, limestone, and shale beds resting on an irregular, and
exceedingly ancient surface composed of granite and allied rocks. The
rocks above this old surface are more or less perfectly known in adjoining
regions where they are exposed and where they have been examined and
described. Their thickness and their lithologic character, however, vary
from place to place, so that whereas their presence may often be predicted
where they are not exposed, the exact thickness and relation of the
beds to each other can not be known with certainty at places far from the
outcrops in anticipation of drilling.

Cambrian and Ordovician Rocks

The basal granitic rocks which are pre-Cambrian in age have never
been penetrated in central Illinois. The deepest well in the area, the Mark
Flitz well, drilled by the Producers Oil Company on the flood plain of
Long Branch in sec. 7, T. 8 N., R. 5 W., is 3770 feet deep. At a depth
of 2685 feet the boring passed into a limestone which is thought to be
the top of a series of Cambrian and Ordovician rocks which overlie the
granite and underlie the St. Peter sandstone. Only 85 feet of the limestone
series was penetrated in this well, but in southwestern Missouri where
the rocks outcrop at the surface the rocks underlying the St. Peter sand¬
stone consist of 2100 feet or more of magnesian limestone containing sev-

OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES

eral thin sandstone beds, a thick sandstone bed of irregular development
usually resting on the rough surface of the granite rocks beneath the
magnesian limestone series.

The St. Peter sandstone 2 , known widely as a source of artesian water,
was penterated at a depth of 2570 feet and is 115 feet thick; but here, as
well as at other points in the southern part of the State, the water is very
salty and quite unfit for domestic use. The Kimmswick and Plattin lime¬
stones overlie the St. Peter. They have a combined thickness of 808 feet
and include 195 feet of shale 115 feet above the base and a 35-foot bed
of sandstone 48 feet below the top. The Maquoketa shale, which overlies
the Kimmswick and Plattin limestones, is 120 feet thick with 12 feet of
limestone 35 feet above the base.

Silurian and Devonian Rocks

The Silurian system is thought by T. E. Savage to be represented by
24 feet of limestone referred by him to what he calls the Alexandrian
series, in which he includes the Cape Girardeau limestone. The Devonian
is apparently absent, though the overlying shales may include deposits of
this age.

Mississippian Series

The Mississippian series of the Carboniferous system as represented
in the Mark Flitz well consists of 348 feet of shale at the base, which is
mostly Kinderhook, though possibly some Devonian strata are included;
and of 530 feet of limestone of the Osage and Meramec groups at the top.
In this well 105 feet of sand is reported at the base of this limestone series.
Sand is not known elsewhere at this horizon and the accuracy of the log
is questioned. This is overlain by 125 feet of limestone succeeded by 15
feet of sandstone and 285 feet of limestone representing the Burlington,
Keokuk, Warsaw, Spergen, and St. Louis limestones of the Osage and
Meramec groups. The top of the limestone series is believed to be the
St. Louis limestone.

The Chester group, which contains the oil-bearing sands of the Carlyle
field, if present at all at this point has very slight development, and the
beds are not distinguishable in the log. At the close of Mississippian time
the rocks appear to have suffered some deformation and very considerable
erosion, so that the surface was underlain at some points by beds which
had elsewhere been cut away. Five or six miles south of the Mark Flitz
well some of the Chester beds appear to have been preserved. Fifty to
seventy-five feet of sandy beds, beginning with red shale is reported here
in several wells; but in a deep well north of Nokomis, 16 miles northeast of

2 The log of this well was interpreted by T. E. Savage and R. S. Blatchley in Bull. 28, Ill.
Geol. Survey, pp. 20, 21.

OIL INVESTIGATIONS

Hillsboro, over 250 feet of Chester beds, consisting chiefly of green, white,
gray, and red shales was penetrated.

Pennsylvanian Series

GENERAL STATEMENT

The Pennsylvanian series has been divided into three formations, the
Pottsville extending from the base of the coal-bearing rocks to the base
of the Murphysboro (No. 2) coal; the Carbondale comprising all strata
from the base of the Murphysboro (No. 2) coal to the top of the Herrin
(No. 6) coal; and the McLeansboro including all beds from the Herrin
(No. 6) coal to the top of the “Coal Measures.”

The Pottsville rests on the old eroded surface of the Mississippian
rocks and is overlain conformably by the Carbondale formation, which
is composed chiefly of shale, sandy shale, sandstone, and several widely
worked and valuable coal beds. In fact, the Carbondale formation con¬
tains most of the coal beds mined in Illinois, the coals of the other two
formations rarely being found sufficiently thick for profitable exploitation.
The Carbondale formation is overlain by the McLeansboro formation,
composed of shales, sandy shales, thin coal beds, and several conspicuous
limestone members.

The identity of the Murphysboro (No. 2) coal in the Gillespie-Mt.
Olive quadrangles has been determined by faunal and stratigraphic evidence.
Fossil plants associated with the coal as determined by David \Yhite ::
indicate that the coal worked in the Litchfield mine is not far below the
top of the Pottsville formation. Comparison of the logs of wells in Jackson
County to the south and La Salle County to the north, where the Murphys¬
boro (No. 2) coal has been worked, with the logs of wells in this area and
at intervening points, indicates the fifth of a series of six coal horizons
below the top of the Carbondale formation as that of the [Murphysboro
or No. 2 coal. This is the next coal above that w r orked in the recently
abandoned Litchfield shaft and the stratigraphic correlation is therefore
consistent with the paleontologic evidence.

The Herrin or No. 6 coal, whose top is the dividing line between the
[McLeansboro and Carbondale formations, is a thick coal underlying a
persistent limestone horizon in the lower McLeansboro formation known
for the presence in it of a small fossil, Girtyina ventricosa. This fossil
has been referred to in earlier reports by a number of names chief of
which perhaps is Fusulina sccalica. In size and shape it is not unlike a
grain of wheat. This coal is the most conspicuous bed in the entire Penn-

The lenticular coals known as Nos. 3 and 4 in this report are valuable as correlation beds
in the district under consideration and for convenience they are designated by number. These
numbers are not intended to apply to coals in somwhat similar positions in the geologic section
throughout the State (Editor).

3 W'hite, David, Paleo-botanical work in Illinois in 1908: Ill. Geol. Survey, Bull. 14, p.
294, 1908.

OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES

sylvanian series in this part of the State and is the only coal bed at present
worked in this area.

POTTSVILLE FORMATION

The Pottsville formation, by reason of the irregular surface on which
it was deposited, is variable in thickness. Near Hillsboro it is 125 feet
thick, near Litchfield 150 feet, and south of Carlinville 100 feet. In a
drilled well three miles north of Plainview only 75 feet of Pottsville beds
appear to be present and it seems probable in consequence that a low
hill was present in this vicinity on the old surface, at the close of Mississip-
pian time.

Although sandstone and sandy shales have been reported at every
horizon between the top of the Mississippian rocks and the Herrin (No. 6)
coal, it may be said that the horizon of the Murphysboro (No. 2) coal
marks a change in general character, sandstone beds being much more
common below than above. In the Pottsville the strata consist chiefly of
alternating sand and sandy shale beds in which the sand predominates.
As reported in the logs there is apparently no continuity in any of the sands,
and the conclusion seems to be justified that they are broken and inter¬
rupted. They seem to be either distinct lens-shaped bodies of limited
extent or merely represent localities where less clay was deposited by
the shifting currents than elsewhere. Certain beds have a local continuity,
and certain parts of the series of beds are more sandy than others, but
there do not appear to be any widely spread sandstone beds. Particular
interest attaches to the sandstone of this formation since the oil and gas
of the Carlinville and Litchfield pools comes from lenticular sandstone
bodies near its top and below the base of the Carbondale.

Only one coal bed is known to occur in the Pottsville of this area.
It is the lowest of a series of six coals below the top of the Carbondale
formation. At the Litchfield mine it lies 250 feet below the top of the
Herrin (No. 6) coal and 40 feet below the base of the Murphysboro (No.
2) coal. Stratigraphically it corresponds to and may be equivalent of
coal No. 1 of Worthen.

CARBONDALE FORMATION

The Carbondale was deposited above the Pottsville apparently with¬
out any greater interruption to sedimentation than is indicated by the
oscillating conditions recorded in the change in sediments within the for¬
mations themselves. The formation is much more uniform in thickness
than the Pottsville, since the accumulation of Carbondale deposits began
on an already leveled surface. The variation in thickness is only between
205 and 220 feet. It consists chiefly of shales, sandy shales, sandstones,
several valuable coal beds, and a few thin limestones.

OIL INVESTIGATIONS

As in many other localities the basal member of the formation, the
Murphysboro (Xo. 2) coal, is in most places bifurcated and consists of
two thin coal beds. These beds have not been reported in all the logs
of wells bored to the depth of this coal, but beds of black shale thought
to be representative of it are present in some localities.

About 75 feet above the base of the Carbondale and about 135 feet
below the top of the Herrin (Xo. 6) coal lies a group of coal beds occupy¬
ing the stratigraphic position of Worthen’s coal Xo. 3. The two prin¬
cipal beds are separated in most places by 5 to 8 feet of shale and lime¬
stone, the latter being from 1 to 4 feet thick. The thickest of these beds
is probably the coal formerly worked in the old Litchfield mine east of
town where, however, only one coal bed 4 feet thick was reported without
any associated limestone. In many of the logs a thin limestone layer,
which, however, may be concretionary, is reported just above the coal;
in some a thin layer is also reported below the lower bench. In a few
of the logs a third bed of coal is present as in the Litchfield shaft north of
town, where three beds of coal are separated by two thin limestones and
associated shale.

This coal bed, or perhaps group of coal beds, and associated lime¬
stones are present in logs of wells in Marshall, Livingston, Macon, Scott.
Cass, Macoupin, and Montgomery counties and may be regarded a valuable
datum plane in this part of Illinois when used in connection with other
well-known strata. The following section of this group of coals from
the Litchfield shaft is typical.

Section of coal (Wortlien No. 3) and associateed strata at Litchfield shaft

Sandy shale .

Black shale.

Coal .

Shale .

Limestone .

Shale .

Coal, slaty .

Coal .

Shale .

Limestone.

Shale, dark.

Coal .

Shale and fire clay

Thickness
Ft. In.

2
3
1

-y

19 3

The absence of the highest or lowest coal bed would make an apparent
reversal in the order of the limestone reported so frequently at this horizon,
thus giving the appearance of a limestone above or below the coal. The
limestone is not an associate of this bed to the southeast, though it appears

OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES

to be present to the southwest in Madison and La Salle counties, where
probably for the reason suggested above limestone appears to lie above
the coal.

Approximately 40 to 60 feet above No. 3 coal group is a bed which
appears at the stratigraphic position of Worthen’s coal No. 4. It is 75
to 100 feet below the top of the Herrin (No. 6 ) coal; and though it has
been frequently reported to be of workable thickness in the drill records,
it has never been mined to any extent, due probably to its thinness in the
two shafts which have been sunk to the deeper coal beds.

The Springfield (No. 5) coal lies from 40 to 50 feet below the
Herrin (No. 6 ) coal. It has a thickness of only 2 or 3 feet and usually
less, and is frequently reported as a very thin sheet of only a few inches.
It appears not to be present at many localities for it is not reported in
many carefully kept logs.

The Herrin (No. 6 ) coal is the principal bed of the region and the
only one mined in the district at present. It has a thickness of 5 to 8
feet throughout the greater part of the area, but in a strip 5 or 6 miles
wide extending north and slightly east of south from Litchfield the coal
is thin or entirely absent. In the eastern part of the field, particularly near
Hillsboro, the coal appears to have been cut away after deposition, for
it is absent in channel-like areas. An important advantage in mining the
seam is the prevailing limestone roof. Locally, however, the limestone
has been replaced by shale, and this has caused the abandonment near
Mt. Olive of otherwise valuable bodies of coal. Throughout a considerable
part of T. 9 N., R. 6 W., and locally in the northern part of T. 8 N.,
R. 6 W. and T. 8 N., R. 5 W. this condition exists. The position of the
Pottsville and Carbondale coals is typically shown in the following log
of a well located in the northeast quarter of sec. 29, T. 9 N., R. 5 W.

Log of well , sec. 29 , T. 9 N., R. 5 W.

Description of strata

Thickness

Depth

Ft. In.

Surface .

Sand .

Hardpan.

McLeansboro formation

Clay, sandv, blue.

Limestone .

63 10

Clay .

43 2

107

Sand, green .

120

Gravel .

123

Limestone, broken.

135

Shale, sandy.

137

Slate, black.

138

Shale, sandv .

183

Limestone, dirty .

184

OIL INVESTIGATIONS

Description of strata

Thickness Depth

Ft.

In.

Ft. In.

Slate, black .

185 7

Limestone, dirtv .

187

Coal, slaty .

. .

187 4

Shale, gray .

194

Limestone with shale bands.

# m

199

Shale, sandy .

. .

223

Limestone .

. ,

228

Sandstone .

. .

239

Shale, sandy .

267 6

Shale, sandv .

290

Sandstone .

318

Shale .

382

Limestone .

387

Shale, sandv .

400

Limestone .

403

Shale .

456 5

Carbondale formation

Coal .

457 6

Shale.

No. 6

458 7

Coal .

460

Fire clay .

. .

461

Shale, blue .

. .

463

Conglomerate .

. .

466

Shale, hard gray.

. .

482

Slate, black .

483 6

Coal, No. 5.

484 7

Fire clay .

487

Sandstone .. .

533 2

Coal .

535 6

Shale.

. No. 4 -

. .

535 10

Coal .

, ,

536 6

Shale .

539

Sandstone, shale partings.

. •

556

Shale, dark sandy.

. .

590

Shale, black .

591 11

Coal .

593 9

Shale.

596

Limestone .

. .

599

Shale, soft.

600 2

Coal, slatv .

No. 3

. .

601

Coal .

group

603 7

Shale.. .

605

Limestone .

606

Shale, dark .

608 6

Coal .

. .

609 3

Shale, soft .

613 6

Fire clay .

623

Shale, sandy .

. .

639

Sandstone .

644

OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES

Description of strata

Thickness

Depth

Ft.

In.

Ft.

In.

Slate, black .

648

Coal .

• .

648

Shale.

l No. 2 \

661

Coal .

. .

662

Pottsville formation

Shaie, sandy .

667

Sandstone, shaly.

. .

687

Shale, sandv, dark .

• .

701

Limestone, broken .

. ,

703

Coal, No. 1.

707

Fire clay, hard.

714

Shale, dark .

717

Sandstone, shale parting.

• •

731

Limestone, shale parting .

• •

734

Shale, dark sandy bands.

743

Sandstone, hard .

745

Shale, sandv .

767

Sandstone .

793

Shale, blue .

803

Sandstone .

811

The sandstones of the Carbondale formation, like those of the Potts-
ville, are irregular and discontinuous in character. The Vergennes sand¬
stone member, so conspicuous a feature to the southeast in the Murphys-
boro-Herrin district, does not appear to be present in the Gillespie and
Mt. Olive quadrangles. The interval between the Murphysboro (No. 2)
coal and coal No. 3 is on the whole not sandy. It is true that in one or
two logs a sandstone bed 5 to 8 feet thick is reported, and in some of
the logs the entire interval is said to be sandy shale. The latter description
however, appears in the less reliable logs and in any case is an exception.

Between the horizon of coal No. 3 and the Herrin (No. 6) coal
the greatest diversity and irregularity of deposition of the sands exists. In
the vicinity of Carlinville this part of the section is predominantly shaly
though sand is not uncommon in the central portions. Near Litchfield,
however, this part of the section is predominately sandy, though shale
is also present.

Between the Herrin (No. 6) coal and the Springfield (No. 5) coal
there is locally some limestone of variable thickness, and in some logs a
few feet of limestone is reported immediately below the Springfield
(No. 5) seam, though generally neither of these beds is present.

MCLEANSBORO FORMATION

The beds lying above the Herrin (No. 6) coal in this region belong
to the McLeansboro formation. They consist of a series of shales and
sandy shales, very subordinate sandstones, thin coal seams, and several
conspicuous limestone beds which outcrop. The maximum thickness is in

6—B—31

OIL INVESTIGATIONS

the old abandoned Litchfield mine east of the town, where 380 feet of
measured strata lie above the Herrin (No. 6) coal. Because of erosion
of the upper part the formation thins westward so that the Herrin
(No. 6) coal at the western edge of the area is overlain by less than 200
feet of combined McLeansboro rocks and glacial deposits. In this area
the rocks of this part of the section are well known from prospect holes
bored to the Herrin (No. 6) coal.

The most conspicuous surface features of the McLeansboro formation
are the outcropping limestone members. Two of these are particularly
conspicuous and are practically the only outcropping beds which can be
readily identified. The lower of these beds, which had been named the
Carlinville limestone from its exposures near that town, was in 1907 cor¬
related by Jon A. Udden 4 with the Shoal Creek limestone which outer ips
on that stream near Breese. It appears clear, however, from outcrops in
the head of Cahokia Creek between Gillespie and Staunton that there are
two limestone beds the upper of which is the Shoal Creek, the lower the
Carlinville member. A large number of drill holes in the vicinity and
southward toward Breese corroborate this conclusion, and the members
themselves exhibit distinctly different lithologic characteristics, at least in
the area under question where both are present.

The base of the Shoal Creek limestone is about 75 feet above the Car¬
linville and from 275 to 325 feet above the Herrin (No. 6) coal, but
toward the south this interval increases, being 350 feet at the Future mine
at Breese. It is conspicuously exposed near shaft No. 3 of the Superior
Coal Company and at other points in the vicinity of Gillespie, on Shoal
Creek west of Litchfield, on Lake Fork and on Shoal Creek near Sorento.
and elsewhere. By reason of the glaciation the top of the bed seldom
appears in drilled wells or in exposures since the overlying soft shales
and the upper part of the limestone seem to have been generally trimmed
off by the moving ice sheet. Where not eroded it has a thickness of 12
to 25 feet, but it is not homogeneous like the Carlinville member in that
it consists of a series of more or less argillaceous limestone layers. In
certain localities the top, bottom, or middle is replaced by limy shale.
Near Litchfield it appears to be split into two parts, the lower separated
from the upper by 15 to 30 feet of shale, but it is possible that the lower
part represents a local bed underlying the true Shoal Creek. The face of
weathered exposures presents a ragged appearance due to fine conchoidal
jointing of the thin beds.

The Carlinville limestone lies from 200 to 225 feet above the Herrin
(No. 6) coal but this interval fluctuates, and at the eastern margin of
the field where the logs show the bed thin and irregular, the interval is
thought to diminish to 175 feet. Where best developed the bed has a thick-

4 Udden, Jon A., Notes on the Shoal Creek Limestone: Ill. Geol. Survey Bull. 8, p. 118, 1907.

OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES

ness of 6 to 7 feet, and is tough, gray, dense, and much more homogeneous
in character than the Shoal Creek member. The Carlinville is also less
argillaceous and may be distinguished from the Shoal Creek by its
smoother grain and its method of weathering, the Carlinville breaking into
regular smooth-sided chips, whereas weathered outcrops of the Shoal
Creek member are littered with ragged chips and plates. To the south
toward the Breese and Belleville quadrangles the Carlinville member be¬
comes thin and irregular and can not be positively identified in the logs.
It is possible that it dies out to the south and is merely a lentil. The “top”
limestone mentioned by Udden and Shaw 5 in a description of the Belle-
ville-Breese area may be its equivalent, but this bed is only 100 to 130 feet
above the Herrin (No. 6) coal and probably represents a similar lime¬
stone lentil lower in the section. It seems more plausible to regard the
“top” limestone therefore the equivalent of a sporadic limestone which is
not uncommonly reported in the logs as lying 150 to 175 feet above the
Herrin (No. 6) coal in the western part of the area, though there is nothing
save the interval to justify the correlation.

Intermediate between the Carlinville and Shoal Creek members and
30 to 50 feet below the Shoal Creek member, another limestone bed is
exposed at a number of localities south and west of Gillespie, but this bed
does not appear to be continuous. It is in most places only 2 to 3 feet thick,
but its close association with a continuous, black shale band or thin coal
bed is sufficiently common to suggest that it occupies a definite position in
the section, and that it may prove to be better developed in adjoining areas.

The limestone bed outcropping in the railroad cut east of Plainview
which Worthen regarded as the Carlinville is believed to represent a local
thick limestone bed mentioned above which is somewhat lower in the section
and is shown by logs in this part of the state to lie about 150 feet above
the Herrin (No. 6) coal.

Most persistent of all, in the well records of this part of the section is
the limestone series overlying the Herrin (No. 6) coal. It is in most
places from 20 to 30 feet thick, but in many localities the continuity of
limestone deposition was broken by shale deposits, the limestone alternating
with shale beds and forming a distinct, though heterogeneous, group. This
limestone bed, which is one of the most useful criteria for identifying
the Herrin (No. 6) coal by reason of its persistence and the presence in
it of a small, distinctive fossil, is absent, however, in most of the logs in
a strip from northwest to southeast through the central part of the area.

Another persistent member is a bed of red, or brownish, clay shown
in the above section. It is usually reported from 40 to 60 feet above the
coal. This bed, although having a variable position, lies above the first
thin coal bed above the Herrin (No. 6) coal. It is widely recorded in

5 Udden, J. A., and Shaw, E. W., U. S. Geol. Survey, Geol. Atlas, Belleville-Breese folio
(No. 195), p. 6, 1915.

OIL INVESTIGATIONS

logs, being present at least as far north as the Springfield area and reported
in logs 20 miles south of the Gillespie-Aft. Olive quadrangle. It probably
represents a period of elevation and erosion when the iron content of the
exposed shales became oxidized.

Four thin coal members are persistent throughout the area and are

usually reported in the logs. Their general position, as well as that of the
limestones is well shown in the accompanying log.

Log of well in SW. part of T. 8 N., R. 5 W.

Description of strata

Thickness

Depth

Ft. In.

Clay, yellow.

Sand .

Clay, yellow.

Sand.

Clay, blue.

Sand and gravel.

Shale, limy.

Limestone, Shoal Creek.

112

Shale, dark.

149

Coal .

149 3

Shale, clayev.

150

Shale, black.

153

Coal .

153 3

Shale, clav.

5 9

159

Shale, limv.

161

Limestone .

165

Shale, sandy .

175

Shale, dark.

190

Limestone, Carlinville.

196

Shale, sandv.

219

Shale, gray.

239

Coal .

239 6

Shale .

2 6

242

Shale, limy.

251

Shale, sandy.

283

Shale crrav .

331

Shale, dark blue.

11 9

342 9

Coal .

343

Shale, clay.

349

Shale, dark.

354

Shale, clay.

356

Shale red .

364

Shale, limy.

366

T impstnnp .

372

Shale .

376

SDtp hbip .

377

Coal .

1 6

378 6

Shale, gray.

9 6

388

Limestone .

404

OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES

Description of strata

Thickness

Depth

Ft.

In.

Ft.

In.

Shale, dark.

• •

408

• •

Coal, No. 6.

416

Shale, clav.

420

Sandstone beds have been reported in the well logs at all horizons of
the McLeansboro, and though sandy shale is conspicuous above the red clay
horizon, no sharply marked continuous sandstones or sandy horizons are
present.

Quaternary Deposits

Overlying the surface of the McLeansboro formation is a series of
pebbly and sandy clay deposits called drift which varies in thick¬
ness from a few feet to 190 feet. These deposits were accumulated
very much later than the “Coal Measures” and were deposited on them
after they had been worn down by erosion to a surface considerably more
broken and hilly than that which forms the surface today. This old
surface was finally covered by a great continental ice sheet which swept
down from the north bearing with it the debris worn from the rocks over
which it plowed. After the melting of this ice the old valleys in this part
of the State had been completely buried by the debris, and nearly the entire
surface of the State was left with a surface such as that which today exists
on the flat upland divides in this area. Since that time the drainage from
this great flat area has developed valleys and cut deeply into the covering
of glacial drift and in many localities into the rocks of the “Coal Measures”
below.

Sticks, stumps, and buried soils found between the upper and lower
parts of the glacial debris, clearly indicate that this part of Illinois, in
common with areas farther north, was buried beneath at least two successive
great ice sheets, and that a period long enough for the growth of forests
and the accumulation of soil elapsed between the disappearance of the first
ice sheet and the advance of the second. The hills in the vicinity of
Hillsboro were probably built up at the edge of the second ice sheet during
a pause in its retreat, the ice dropping its load at the edge of the glacier
and leaving it behind when climatic conditions caused a melting of the ice.

STRUCTURE
Structure Contours

The position of coal No. 6 above sea level is shown in Plates IX and X
by means of red contour lines. Since the beds above and below the coal
are approximately parallel to it, the contours show the general geological
structure of all the beds. In order that the reader may understand and
interpret the structure contour, he is requested to examine Plate X. The

OIL INVESTIGATIONS

prominent red lines represent the surface of coal Xo. 6 as it would appear
if all the overlying beds were removed.

The reader is requested to imagine the surface of coal No. 6 to be
flooded by a large body of water the surface of which lies 150 feet above
the present sea level. The shore line would be represented by the 150-foot
contour. If the level of the water were raised by 25-foot intervals the
successive shore lines would be indicated by the corresponding contours.
The upward folds or anticlines, as in the western part of Butler Grove
Township, would extend out into the sea as long arms of land, whereas
the downward folds or synclines such as the one north of Litchfield would
be covered by bays and lagoons. If the water stood at the 250-foot contour
line, the dome one mile southeast of Litchfield would be an island 50 feet
above the sea.

It should be borne in mind that the contours show only the larger and
more prominent features of the structure. In parts of the area where
neither rock exposures nor drill holes are available the structure is indicated
by broken lines, to show that their position has been determined by inference
only. The workings of the coal mines show many fluctuations which the
sparsely grouped drill holes fail to reveal.

These fluctuations of the coal usually shown on the floor of coal mines
amount locally to 10 or 20 feet and more and have no apparent relation to
the general structure. As there is no way of determining whether a drill
hole has penetrated an anticlinal or synclinal phase of this subordinate
warping, a certain amount of deviation from the actual structure is thus
inevitably introduced in the structure contour map.

Structure of the Gillespie and Mt. Olive Ouadrangles

The rocks of the area have not suffered marked deformation. The
strata have been warped into irregular and very low domes and shallow
basins without any very definite order of arrangement. As shown in Plate
IX the Herrin (No. 6) coal rises irregularly from an altitude of 150 feet
in the southeast corner to over 400 feet near the western margin of the
area, an increase of elevation of nearly 275 feet. In parts of the area the
strata are practically flat, as in the area southeast of Mt. Olive, where the
average dip is about four feet to the mile toward the east. The steepest
dips occur north of Staunton, where for a distance of about one mile the
beds dip eastward from 25 to 40 feet to the mile, and near Panama where,
about the flanks of a ridge-like structural feature, for a distance of less
than one half mile the dip is over 100 feet to the mile.

The chief structural features are: a trough which may be called the
Shoal Creek syncline, extending from Panama nearly to Litchfield, and
closely following the valley of Shoal Creek; a structural flat 6 to 8 miles
wide extending from Walshville Township northwest into Honey Point
Township; and a gently sloping surface rising from this flat to the west.

OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES

the last feature being greatly modified by subordinate warpings. A less
distinct feature which strongly suggests a gentle anticline diagonally crosses
these larger deformations and extends from sec. 4, T. 9 N., R. 4 W. south¬
westerly toward Litchfield and Mt. Olive. A sharp anticlinal ridge also pro¬
jects from the west side of the Shoal Creek syncline and extends from a
point north of Sorento to a point south of Panama, and around the flanks of
this occur the steep slopes already mentioned. A structural basin which
occurs north of Litchfield is very evident at the Litchfield mine and farther
north. The horizon of the Herrin (No. 6) coal is here depressed nearly 50
feet below its general position. It is probable that this basin extends to the
northward, possibly in continuation of the interrupted Shoal Creek syncline
cut off by the diagonally trending anticline mentioned.

Domes occur in the Carlinville oil field ; in the Litchfield oil field; 3
miles northwest of Staunton; 5 miles southwest of Litchfield; and it is
probable that in an ill-defined area northwest of Butler the strata are higher
than in the surrounding country. Another small area 3f4 miles north of
Plainview is also doubtfully regarded as dome structure. These structures,
which are of particular interest in prospecting for oil, will be described in
greater detail.

Litchfield Oil and Gas Field

The first valuable deposit of oil found in the State was discovered at
Litchfield by the Litchfield Coal Company in November, 1879.° In an effort
to find a lower coal seam sufficiently thick to be profitably mined, a hole
was drilled in the bottom of the shaft which passed into oil-bearing sand
at a depth of 255 feet below the coal and 682 feet below the surface. The
salt water at first threatened to flood the mine, but the hole was success¬
fully plugged, though oil leaked into the mine and was skimmed from the
mine water for several years. The oil was a heavy lubricating oil and
was associated with salt water and gas.

No great excitement such as is now usually manifested attended the
discovery. A few holes were drilled, however, and in 1882 four wells
were being pumped, each producing, according to Worthen, about two
barrels of oil per day. In 1882 the first big gas well was brought in. It
had an initial pressure of 400 to 450 pounds per square inch, but in 1885
in drilling deeper, salt water was struck and the well was spoiled.

In the same year two other gas wells were brought in which had a
pressure of 125 pounds per square inch. The gas was piped to Litchfield
(a distance of about 1^4 miles) by the Litchfield Gas, Oil, and Fuel
Company and was used for cooking and lighting for several years. In
1886 about 500 stoves were supplied, but in 1889 the supply of gas was
equivalent to only 12 tons of coal per year, which was all consumed in

‘’Worthen, A. II., Geol. Surv. of Ill., Vol. VII, p. 37, 1883.

OIL INVESTIGATION5

pumping oil. There were never more than four or five oil wells being
pumped at any one time, though they were reported to yield about 4 barrels
per well a day in 1889. In 1904 two of the wells were still being pumped,
but were closed down soon after on account of the low price of oil, it was
said, though, since the yield had fallen from 1,460 barrels in 1889 to some
200 barrels in 1902, there were probably other reasons. In 1906 new wells
were drilled near the old gas wells Nos. 5 and 15, but they were capped and
so far as known no attempt was made to pump them. Up to 1889 some 30
wells had been drilled in the area chiefly for gas, but all except the five
wells at that time producing oil had been abandoned several years. Since
that time there has been sporadic drilling from time to time without any
success in extending the limits of the productive area.

The oil as reported in “Mineral Resources of the United States in 1889"
was said to be dark, almost black and to have a specific gravity of 22° B.
The cold test was remarkable, the oil remaining fluid at 20° Fahrenheit.
It was used chiefly by factories in the neighborhood of Litchfield and was
sold at nearby points for lubricating purposes at 8 to 10 cents per gallon.

From the time of its discovery until 1902 the production of oil and gas
in Illinois was the production of the Litchfield pool. Between 1889 and
1902 the yield fell from 1460 barrels to 200 barrels per year. During this
period 6,756 barrels were produced. In October, 1882, Professor Worthen
of the Illinois Geological Survey reported that four wells were in operation,
producing two barrels each per day, equal to 2,920 barrels per year. Assum¬
ing a gradual decrease from this time until 1889 when the yield was 1.460
barrels, the production for these years was 13,875 barrels, making a total
production between 1883 and 1902 of 20,451 barrels, which is doubtless
somewhat below the total production since no account is taken of the
production between the discovery in 1879 and 1883. The total production
was probably not far from 22,000 barrels.

The structure of the rocks of the area near Litchfield based on that
of Herrin (No. 6) coal shows a very distinct dome. The same coal beds
found in the oil wells east of Litchfield are about 70 feet lower in the
mine in sec. 33 of the adjoining township, scarcely more than a mile
distant. The dip of the beds toward the southeast is apparent from the
limestone outcrops in the creek southeast of town followed by the C. C. C.
& St. L. Railway. Toward the west the dip is less pronounced, the hori¬
zon of the Herrin (No. 6) coal at the test hole at the southwestern
corner of Litchfield being only about 40 feet lower. Toward the south
the dip near the oil pool is not known, but it is at least 30 feet lower three
miles distant. It is probable that the dome just described was the essential
factor in causing the accumulation of the oil in the Litchfield pool.

Of the older wells six produced oil and seven produced gas. The
oil holes lie in almost a straight line in a tract about one-half mile long

ILL!

BULLETIN NO. 31, PLATE VII

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LEGEND

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ILLINOIS STATE GEOLOGICAL SURVEY

BULLETIN NO. 31, TLATE VII

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sand

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sand

Salt

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Poor

sand

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Sandstone

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Clay and
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Sandy

shale

Brown

shale

Black

shale

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limestone

Fire clay

Coal

Oil

trace

Graphic sections of Litchfield wells
(For location of wells see figure 17)

OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES

and one-eighth mile wide. The gas holes, however, are sprinkled over a
slightly wider area as may be seen from the accompanying sketch map
(fig. 17). Plate VII shows the position of the oil and gas sands in the
different holes. It will be seen that the gas wells lie chiefly to the east of
the oil holes, and that the gas was reached in a sand which lies 40 or 50
feet higher than the oil sand. The distance between oil well No. 13 and
gas well No. 5 is scarcely more than 500 feet, yet the gas sand is nearly

R. 5 W.

Fig. 17. Map showing location of wells in Litchfield pool and order of arrange¬
ment of logs in Plate VII.

50 feet higher than the oil sand as shown by the correlation lines on Plate
VII. This is not easily accounted for, either by flexure or by faulting, since
sharp displacements of the strata in so short a distance due to either of
these causes are not known in this part of Illinois. The most plausible
explanation of the phenomena lies in the probable presence of more than
one sandstone bed, the upper of which was gas-bearing, whereas the lower
was productive of oil. The fact that at the time the field was being

OIL INVESTIGATIONS

exploited the gas was of more consequence than the oil and the fact that
the first gas well was lost by the influx of salt water while drilling the hole
deeper, offers an explanation of the failure to drill deeper in the eastern
part of the field. No complete records of the early drilling have been
preserved, and it is not now known whether the gas sand extended west¬
ward above the oil sand in the area of the earlier producing wells. This
seems in some respects not unlikely since a gas-bearing sand is reported at
the same horizon in the McWilliams well west of hole No. 13, though no
upper gas sand was reported in the surviving fragmental logs of the oil
holes.

It is probable that the oil sand extends beneath the horizon of the gas
sand in the eastern part of the field. In 1906 two new wells were drilled
near the abandoned gas wells No. 5 and No. 15, both of which were
reported to be oil bearing. Whether the holes reached the oil stratum
below the exhausted gas sand, or whether oil during the 16 years since the
exhaustion of the gas had found its way into the formerly gas-bearing
horizon is not known. The wells were capped over without being pumped,
and it seems probable, therefore, that but little oil was encountered.

The productive sands in the Litchfield field, as well as in the Carlin-
ville field, occur at and below the horizon of the Murphysboro (No. 2 )
coal. In the old Litchfield shaft where the first discovery was made, the
oil sand lies below the horizon of the coal No. 1 and below the natural
position of this coal in the McWilliams well No. 3. The sands from which
the chief gas production has come seem to lie higher in the section and in
the McWilliams well No. 3 this sand seems to lie at the elevation of coal
No. 1 and probably cuts it out. The significant feature is that, although
the sands are not continuous, the oil- and gas-bearing lenses correspond very
closely in stratigraphic position to the oil and gas sands in the Carlinville
area and were it not for intervening logs which clearly show the absence
of this sand the beds might easily be correlated. In spite of the frequency
of more or less extensive sand bodies higher in the Carbondale and
McLeansboro formations no oil has ever been found in them, only pockets
of gas being present.

The conditions are somewhat analogous to those existing in the
Carlinville field where, although the doming of the rocks appears to be the
controlling factor in the accumulation of the oil, the character of the sand¬
stone lenses appears to have been the deciding factor in determining what
particular part of the dome should be the repository of oil. The association
of gas in a higher sand with oil in a lower, possibly connecting, bed is also a
parallel circumstance.

Only a few complete logs have been preserved so that a complete
analysis of the field is now impossible. The field will never again reach
its former production, but it seems possible on account of the high viscosity

OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES

of the oil that considerable oil yet remains in the developed area, and that
by drilling to the east of the old oil wells a modest production may be
expected from the deeper sand. The viscosity of the oil preventing its
easy extraction from the sands would seem to warrant the closer spacing of
the holes and the use of modern devices for more complete extraction.
The area has never received systematic development and though there is a
possibility of future production on a small scale the returns will not be
high. No information is available as to whether the holes were plugged,
but it is probable that some were abandoned without plugging. What
effect this may have had on the oil yet in the ground is problematical.

Carlinville Oil and Gas Field

The first knowledge of gas in the Carlinville area was obtained in the
early sixties when a water well was being dug in the glacial drift in sec. 7,
T. 9 N., R. 7 W. The man engaged in digging the well is said to have
paused in his work to light his pipe, thus igniting a small pocket of gas,
which the story relates set fire to his clothing. Led by this discovery, a
well was drilled in 1867 near the east quarter corner of sec. 7; but the
hole was unsuccessful, and prospecting was abandoned. In 1909 pros¬
pecting was renewed in the same area by the Impromptu Exploration
Company, directed by Mr. T. A. Rinaker, and a small gas field was
developed which was sufficient to provide illumination for Carlinville for
two or three years. Continued exploration toward the east in November,
1911, developed a small oil pool which has had a reported production up
to the close of 1914 of 16,540 barrels. An isolated gas well was drilled in
the early part of 1912 on the Hammann farm near the center of the north
line of sec. 16, T. 9 N., R. 7 W. The pressure is said to be between 85
and 90 pounds, but the owner was unable to come to terms with the Litch¬
field gas company and the well is now capped, and no effort is being made
to use the product. The bottom of the well is 507 feet, below the surface
and 295 feet below the top of the Herrin (No. 6) coal. The gas comes,
therefore, from the lowest of the Pottsville sands recognized in this area.

The gas in the Carlinville area was reported to be of good quality and
similar to that at Greenville and Jacksonville. It is said to have been
almost odorless and colorless, and to burn with a hot, blue flame. The
initial pressure was 135 pounds but in 1912 it had fallen to about 35
pounds.

The oil is dark brown and semi-viscous and has a specific gravity of
28.6° B. It is said to resemble the oil formerly produced in the old Litch¬
field pool and the Duncanville heavy oil of Crawford Company, though the
former was considerably heavier than that found here.

The structure of the oil- and gas-producing area at the horizon of the
Herrin (No. 6) coal is a low dome crowning a long eastward-sloping
surface having a dip of about 10 feet to the mile. The height of this dome

OIL INVESTIGATIONS

does not exceed 20 feet at the horizon of the Herrin (Xo. 6) coal, but at
the horizon of coal No. 3 and its accompanying limestone bed, and at the
uppermost of the gas-bearing sands, the dome is accentuated as may be
seen on Plate VIII. Figure 18 shows the dome by contour lines on the

C/i

C/3

Herrin (No. 6) coal and on the highest sandstone bed. As may be seen,
the deformation of the two surfaces is practically concentric. The Herrin
(No. 6) coal bed has, however, not been reported in all the logs, and it has

ILLINOIS STATE GEOLOGICAL SURVEY

FEET

600

While

White

While fc

While

IV5 Whllo

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Graphic sections of Carlinville wells
(For location of wells see figure 19)

BULLETIN NO. 31, PLATE VIII

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OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES

been necessary to determine its position in some of the wells by correlation
of the logs on the overlying limestone and black shales. This may account
for the apparent deviation.

Whereas the doming of the rocks at this point was probably a very
important factor in localizing the oil pool, other factors such as the slope,
continuity, and porosity of the sand beds at different places were equally
important. The discontinuity of the sandstone beds was recognized by
F. H. Kay 7 who reported the field in 1912, but no attempt was made at
that time to distinguish the productive sandstone lentils. Several new wells
have been drilled in the past two or three years, and it now seems possible
to distinguish four productive horizons only one of which, however, has
been commercially profitable.

Plate VIII shows the essential relations of the various sandstone
horizons to one another. A little gas has been reported in several wells in
the black shale immediately overlying the Herrin (No. 6) coal. The high¬
est gas-bearing stratum of any importance, however, was penetrated by
the Klein No. 1 well, which passed into 30 feet of gas sand at a depth
of 350 feet. The horizon of this sand is that of the upper bench of the
Murphysboro or No. 2 coal, which, if no error has been introduced in
reporting the log, has been replaced at this location by sand. The fact
that no sand was reported at this position in either Denby No. 1 or V.
Hall No. 1 wells one-half and one-fourth mile distant respectively, nor
in any other log in the field except the Mutzbauer well in sec. 23, T. 9 N.,
R. 8 W. suggests either that the gas comes from an isolated sand lens,
or that an error has crept in the log, and that its actual position is some¬
what deeper. The sand reported in the Mutzbauer well seems to substan¬
tiate the log of the Klein No. 1 well, at the same time suggesting a zone
of sandstone lentils above the sands about to be described. The possibility
of sharp flexure at this point seems to be discounted by the regularity of the
sandstone below the Murphysboro (No. 2) coal and by limestone accom¬
panying coal No. 3 group.

The next sand bed of interest lies 20 to 25 feet below the upper
bench of the Murphysboro (No. 2) coal and is closely overlain by a bed of
black shale, which may represent the lower part of the Murphysboro
(No. 2) bed itself, this bed appearing in several of the logs in other parts
of the quadrangles as a bifurcated seam. In the central part of the
area this bed, which is gas-bearing at nearly every point penetrated, has
a thickness of 6 to 8 feet with thin breaks enclosing, in one or two
places, thin sheets of slightly oil-bearing sand. It thins toward the east
and south, but even where no sand was reported the overlying black shale
was found to contain some gas.

7 Kay, F. H., The Carlinville oil and gas field: Ill. Geol. Survey Bull. 20, 1912.

OIL INVESTIGATIONS

In the Haake No. 1 well in sec. 17 a sandstone bed immediately
underlies “black slate” at the horizon of the lower bench of the Murphys-
boro (No. 2) coal. This is thought to represent in part a sandstone
lens deposited in a channel cut down into a lower sand with the essential
relations shown at A in figure 20. The sandstone reported in the V.
Hall No. 1 well also probably represents a similar thickening of this
sandstone, as does also the upper sand in Denby No. 1. This bed has
been productive of* a moderate quantity of gas and a little oil, but the
sandstone which lies just below has been more productive.

The chief oil and gas horizon is commonly separated from the bed
just described by 15 to 25 feet of shale. It lies at the horizon of coal
No. 1 about 385 feet below the flood plain of Macoupin Creek and appears
to lie in a channel cut into the beds somewhat later than the deposition of
this coal. The reason for so regarding it, is that although this productive
sand horizon is present in the wells drilled east of a general northeast-
southwest line drawn between the V. Hall No. 3 and V. Hall No. 7 wells,
it is absent to the west. In the Denby No. 1 well west of this line this
part of the section contains coal No. 1, whereas in the V. Hall No. 3 well
at the horizon of coal No. 1, black shale is reported. As black shale is
frequently reported in place of this coal in wells in other parts of the
district it is thought to be represented in this log.

In the other holes west of this line either the interval is reported as
shale, which is a conventional non-committal report in careless logs when
no sand is present, or the interval is not reported at all. Whether the
sand reported in the V. Hall No. 1 well is really an excessive thickening
of the higher sand bed or whether it represents a protruding arm of the
lower, more productive sand may be open to question, though the former
appears most probable, from its stratigraphic relations. East of the line
mentioned all of the holes which penetrate to this depth show sand at the
position of coal No. 1.

The chief producing bed is from 30 to 45 feet thick and is split into
an upper gas-bearing sand and a lower oil-bearing sand by a break of shale
5 to 10 feet thick. If it were not for the fact that in the Hall No. 7
well these gas- and the oil-bearing horizons are in contact without am-
intervening shale, the two sandstones might be considered as separate
and distinct beds, as indeed they are in effect in most of the wells. It
is probable that the shale parting between the beds is absent at other points
and that communication from one to the other is thus facilitated, as sug¬
gested by the practical absence of oil from the upper bed and of gas from
the lower.

In the Anderson well one-half mile to the south of the producing
wells, this sand is represented by one bed 27 feet thick lying, on account
of the dip, somewhat lower than in that area. Here it is reported to be

OIL AND GAS IN GILLESPIE ANI) MT. OLIVE QUADRANGLES

very fine grained and nearly dry. In the Freeman Hall No. 2 well
drilled by the Impromptu Company only a thin, slightly oil-bearing sand
is reported probably about the bottom of the lower part of this member.
Adjacent parts of the section are not reported, but whether the sand is
actually thicker than reported or not, the fact remains that the oil-bearing
portion of this member appears to be present. As already stated the oil- and
gas-bearing parts of this sandstone are in contact in the V. Hall No. 7 well
without any intervening shale. Toward the west, however, a sudden
change is to be noted between this well and the V. Hall No. 3 well, black
shale replacing the sand in the latter. No sandstone was reported at the
horizon in the log in the Freeman Hall No. 1 well of the Ohio Oil Com¬
pany, but as the producing member is reported in the Freeman Hall No.
2 well of the Impromptu Company, only a short distance east, a similar
wedging out is thought to occur between these holes also.

Still another and deeper sand is encountered below the chief producing
sand. It lies about 25 feet below coal No. 1 and appears to be a more
persistent and continuous layer than any of the others. It appears in the
logs of all the wells in the field which have penetrated to this depth, but it
has been found to contain chiefly salt water, though in a few instances,
notably the Ohio Oil Company well on the Freeman Hall farm, the Best
No. 1 well of the Impromptu Exploration Company, and others, traces of
oil and small quantities of gas were observed. Its relations to the higher
sands is shown in Plate VIII.

Figure 19 shows the location of all the oil wells drilled in the district.
It should be noted that the arrangement of oil and gas wells in the area
has little significance since some of the holes report the condition of one
sand bed and others of another. They therefore do not indicate any
obvious relationship to the structural dome shown in figure 18.

Plate VIII, though primarily designed to show the correlation of the
sands, shows also in a rough way the structure of the area in cross-section,
the logs being arranged as shown on the key map (fig. 19). Plate VIII is
intended to show also that there is no one particular oil or gas sand, but
that at and below the horizon of the Murphysboro (No. 2) coal there are
present a number of sands any of which under favorable conditions is
capable of receiving and retaining oil and gas; that the principal bed in
which oil has been found is one which lies at the horizon of coal No. 1 ;
that this bed is not a continuous sheet extending across the area like the
coal beds and some of the limestones, but that it occupies what was origin¬
ally a broad shallow valley cut into the rocks not long (geologically speak¬
ing) after the formation of coal No. 1.

This valley which no doubt had the usual irregular configuration of a
shallow drain with more or less meandering course and subsidiary tribu¬
taries was later filled with silts of sand and mud of more or less varying

OIL INVESTIGATION’S

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grain and distribution. Sand was deposited at one point and sandy shale
or shale at another until the original channel was filled and covered. The

OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES

first deposits however seem to have been sands though shale appears in the
middle part of the filling in some places.

The width of the sand filling the old basin is not sharply defined by the
drilling. It is present in the Liston No. 1 well in sec. 9, but the black shale
horizon of coal No. 1 appears in the logs of the Best and Sellers wells
in sec. 10. The width of the old valley at this point appears to be about
\y 2 miles. On the east of the channel the lens is 35 or 40 feet lower than
on the west, and there is therefore less opportunity for oil to accumulate
since there is a tendency for it to rise toward the highest part of the porous
sand body. Small pockets of oil or gas may, however, occur beneath the
irregular roof shale, and some may be trapped by so-called “breaks’ 1 in
the strata, but the eastern side of the sand body at this point is regarded
as distinctly unfavorable.

The breaking off of the sand in sec. 7 between the V. Hall No. 7
and the V. Hall No. 3 wells and between the Freeman Hall No. 2 well of
the Impromptu Oil Company and the Freeman Hall No. 1 well of the
Ohio Oil Company already discussed, indicates that the approximate
margin of the sand passes between these wells. To the south it is appar¬
ently present in the Haake No. 1 well in sec. 17, where it is unproductive,
probably on account of its lower elevation, and absent in Klein No. 2 well
in sec. 18, half a mile to the northwest. Toward the north the information
at hand is inadequate though the main oil-bearing sand, if present (which is
doubtful), might be included in 140 feet of undififerentiated sandy shales
reported immediately above the gas sand in a deep well in sec. 5. The
gas-bearing sand in this well is believed to be the basal or lowest of the
sand horizons recognized in the wells so far drilled. The later deformation
and tilting of the beds provided a pocket in the wedge-shaped uptilted edge
of the lense favorable to the accumulation of the oil particles as they
migrated upward through the sandstone. The oil as now found occurs at
a point along the edge of the lens where gentle doming of the rocks has
capped the edge of the porous strata and efifectually prevented the escape
of the oil along the bedding planes as shown in figure 20. The doming
caused a portion of the sand wedge to be elevated, thus forming a partic¬
ularly favorable situation for the accumulation of oil and gas.

It is thus seen that, whereas the uptilted wedge of sand was a favorable
condition, the accidental occurrence at its edge of a gentle dome made the
situation especially good for trapping the oil migrating through the porous
sands of the old channel.

Although the possible presence of oil and gas in the other sandstones
should not be lost sight of, the chief interest naturally centers in the sand¬
stone which has been the chief producer. Future drilling should take into
account the form and character of the reservoir in which the oil is found.
The most favorable location, as just stated, appears to have been beneath

7—B—31

OIL INVESTIGATIONS

Fig. 20. Idealized section through a dome, showing sand-filled channels in cross-section, points of accumulation ol oil and gas, and
direction of migration.

OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES

the domed edge of the sandstone lens which has already been rather well
prospected. The next most favorable situation appears to be along the
continuation of the margin of the old channel to the northeast and south¬
west and on the dip to the east. The dip to the east has been prospected by
the McClure wells No. 6 and No. 8, the latter of which was found to be
dry at a depth of 500 feet. The F. Hall No. 2 well of the Impromptu
Company, though a little oil was found in it, did not give much promise
for future prospecting to the north. A hole recently drilled 680 feet north
of Y. Hall No. 7 is said to have proved dry also. These holes seem to
prove the futility of further prospecting in this direction in the immediate
vicinity of the dome.

The dome appears to be much sharper on the north side, however, than
on the south, so that the probability of slight extension of the producing
area toward the south is better. V. Hall No. 6 is the only hole drilled
south of the producing area; this hole is at some distance from the probable
edge of the productive sand lens, and too far away from the nearest
producing well to condemn the intervening territory. The depth to which
it was drilled is not known. Favorable unprospected territory probably
lies just east of the dotted line in figure 19 and not far south of V. Hall
No. 7 well.

The question of the extension of the field seems to turn on whether
the reservoir was provided by the dome or by the shape of the sandstone
body. If the former was the controlling factor the limits of the pool as
outlined at present seem to have been reached. If the latter was alone
sufficient to cause accumulation of the oil, then doubtless other producing
areas will be found along the edge of the old basin. It must be admitted,
however, that even taking into account the probable meandering course and
variable nature of the edge of such a sand body, the evidence at hand
seems to limit the oil-producing area to the part of the sand beneath the
dome.

The area, however, should not be abandoned without investigating the
influence of the dome on the lowest sandstone bed. It has been shown bv

several borings that traces of oil occur in this bed in areas structurally
inadequate to effect accumulation and indicate that oil has traversed the
bed. An area favorable to accumulation and retention, however, occurs
beneath the dome, and as there is reason to believe that this lowest sand¬
stone is there present, the conditions are believed to be worth testing in the
lower sand at this place.

General Relations of Oil to Structure and Stratigraphy

Whereas the study of the Carlinville and Litchfield oil pools is less
satisfactory than it might have been had more detailed logs been available,
the information at hand is in many respects unusually good, particularly
in the Carlinville field. The small size of this pool makes it possible to

100

OIL INVESTIGATIONS

obtain a more comprehensive understanding of the conditions than is
usually the case in the larger oil pools. The most important point brought
out appears to be that the oil does not occur in distinct, continuous sand¬
stone bodies, but is found in sandstone lenses which are locally discontin-
uous but which may have been simultaneously deposited in different local¬
ities. Thus, whereas the producing sand near Carlinville which is deposited
at the horizon of coal No. 1 is of only local development, a similarly situated
gas-bearing sand which cuts out coal No. 1 in the Litchfield area in the
same manner may be its stratigraphic equivalent, though there is no direct
connection between them.

Another point plainly indicated is that although the doming is important
and probably is the ultimate controlling factor in causing accumulations of
oil and gas, the position, shape, and inclination of the sand lenses is also
important in governing the local relations of the oil to the dome. It will
be readily understood that the uptilted edge of a sandstone lense is in some
respects favorably suited to the trapping of oil. There is, however, a
tendency for the oil and gas to escape along the bedding planes of the
enclosing strata as indicated by the arrows in figure 20. There must also
be a tendency for these materials to travel longitudinally along the edge
of the wedge unless this is horizontal or the irregularities in deposition of
the sand present barriers to such circulation.

It should be evident then that it is possible for accumulations of oil
to take place where no deformation at all is present, but so far as known
oil has not been observed under such conditions in western Illinois. It is
probable, therefore, that sandy, and usually micaceous, shales enclosing
the sandstones in the lower Pennsylvanian are not sufficiently close
grained or impervious to prevent the circulation and escape of oil and
gas under pressure along bedding planes.

The occurrence of a dome at the edge of a sand lens unquestionably
prevents the escape of oil in the manner suggested, except in so far as
minor losses occur transverse to the overlying beds.

The accumulation of oil, therefore, while occurring beneath a dome
(except where it is found in a continuous sandstone stratum or in a lens
completely underlying the dome), is likely to have an eccentric distribution
in regard to the structure, no oil at all occurring on one side of the dome.
These conditions are shown graphically in figure 20. the arrows indicating
the probable direction of migration of the oil and gas.

The presence of impervious parts in a sandstone bed would tend to
restrict the oil to the more porous parts of the bed. Therefore, a single
unproductive well drilled into a producing sand at a point where the sand
was locally close grained need not necessarily condemn the immediately
adjacent territory, though of course this is often the case.

The movement of oil, gas, and salt water from one part of a sandstone

SURVEYED U
U. S. GEC
GEORGE OT

-LINOIS STATE GEOLOGICAL SURVEY

AMBERLIN. E j. JAMES. COMMISSION'

BULLETIN NO. 31, ELATE IX

R B Marshall, Chief Geographer
W H Herron Geographer in charge
Topography by Frank Tweedy, C W. Goodlove.

L. L. Lee. and R.M Herrington
Control by J.H.W.Ison and R.G.Clinite

Surveyed in 1912

»J»Vf*tO IN COOeenAT'ON WITH TMt AT ATI OF ILLINOIS

/ /, j , ._{§ ~ _ t P Tr7

Contour interval 20feet.
Datum is nxeart sea ZewL

TOPOGRAPHY AM) GEOLOGIC STRUCTURE. GILLESPIE QUADRANGLE

LEGEND
• Diamond drill
+ Churn drill
X Mine shaft
▼ Rock outcrops used
y Contour showing elevation of top Herrin (No.67
coal above sea level Interval 25 feet

OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES

101

series to another by interconnecting sand lenses is suggested in the ideal¬
ized sketch in figure 20. At the point marked ‘‘A" deposition of sediment
gave place to erosion, and a local channel was cut sufficiently deep to expose
the underlying sand body. This being later filled with pervious sand
furnishes an escape into higher strata in the manner indicated by the arrows.

A careful study of all the available logs indicates that above the
Herrin (No. 6) coal the deformation of the lower beds is closely reflected
in the upper beds; the structures are shown in the succeeding overlying beds
in the same localities. The higher beds above the Herrin (No. 6) coal,
however, appear to be more deformed than the lower beds in anticlinal
areas. This appears to be due to a consistent thickening of the intervals
between recognizable datum planes at points of bending, so that in anticlinal
areas the deformation is accentuated, and in synclinal areas the structures
are softened in passing upward from the Herrin (No. 6) coal. What the
explanation of this phenomenon may be, or whether it is even a general
fact of importance beyond the confines of this area can not now be said.
The only area in which this relation between structure and depth could be
studied below the Herrin (No. 6) coal is that of the Carlinville oil pool.
Here the reverse appears to be true, the dome which characterizes the
structure of the producing area being much less pronounced at the horizon
of the Herrin (No. 6) coal than below. Whatever the quantitative relation
between the deformation at different horizons, the fact remains that
deformation at one horizon is usually significant of similar deformation
beneath. A single possible exception to this rule was found where a slight
deformation of the Carlinville limestone failed to be reflected in the beds
below, but as some doubt exists at this point as to the presence of the true
Carlinville limestone, the exception is not damaging to the general
conclusion. Eccentricity of the position of the oil beneath the domes,
however, has already been explained.

Anticlinal Areas Favorable to the Accumltlation and Retention

of Oil and Gas

As has already been stated, in these quadrangles the surface of the coal
on which the conception of the structure is based is very irregularly warped,
rises brokenly from east to west, and attains an elevation on the west
approximately 275 feet higher than on the east. Besides the domes in the
oil-producing areas near Carlinville and Litchfield already described in
detail, a number of other more or less sharply accentuated domes were
discovered which are shown in Plates IX and X.

STAUNTON DOME

The Staunton dome previously described by R. S. Blatchley, 8 appears
to lie somewhat farther west than appeared from the evidence available at

8 Blatchley, R. S., Oil and gas in Bond, Macoupin, and Montgomery counties; Ill. State
Geol. Survey, Bull. 22, p. 41. 1913.

102

OIL INVESTIGATIONS

that time. The dome is low, having an elevation, so far as known, of only
about 25 feet above the lowest point to the south. It is about 3 miles long
and V/ 2 miles wide within the 350-foot contour line and the highest known
point of the coal within this area lies near the margin and is 15 feet higher.
Only points about the margin of the dome are known, however, and it is
possible that near the center the coal is higher and that the dome is more
pronounced than present information indicates. Toward the east the coal
surface slopes rather gently to the next lowest contour elevation; toward
the north and west it falls to 330 feet before rising again to the west; at
the south end, however, it is separated from the westward-rising slope by a
narrow saddle, probably not lower than 340 feet. As there are no exposures
or wells in the central part of the dome, only prospecting can determine
whether the central part rises sufficiently high to trap effectively the migra¬
tory oil in the sandstone beds without the existence of sandstone lenses.
The highest part of the dome lying above the 350-foot contour contains the
southwest and southeast corners of secs. 13 and 14 respectively, the east
half of secs. 23 and 26, the west half of secs. 24 and 25, and the northeast
and northwest quarters of secs. 35 and 36 respectively.

SPANISH NEEDLE CREEK DOME

One and one-half miles slightly east of south from the Carlinville gas
and oil pool a series of exposures of the Carlinville limestone in Spanish
Needle Creek indicate a rather sharp dome which, if transmitted downward
to the coal and sandstones, denotes a deformation of nearly 45 feet at the
horizon of the oil sands. The highest point of the dome as indicated by the
limestone outcrops, lies at the center of the northeast quarter of the south¬
west quarter of sec. 21, T. 9 N., R. 7 W. A subordinate point on the same
dome lying nearly as high was noted at the SE. % NW. Ct NW. J4 sec. 28.
That part of the coal which lies above the 375-foot contour underlies an
area in sec. 21 and the NE. % sec. 28, T. 9 N., R. 7 W. about 1J4 miles
long and of indeterminate width. The highest limestone outcrop represents
an elevation of 407 feet in the coal and the subordinate high outcrop to
the southeast represents a height of 395 feet. The axis of the dome
probably extends from northwest to southeast.

Toward the east the surface of the coal slopes off toward the next
lowest contour. Toward the northwest the lowest point is 362 feet near
the center of sec. 17, indicating a gentle slope in this direction. Toward
the west there is little information in the immediate locality, but in sec. 29
two miles to the southwest the elevation of the coal sinks to 365 feet.
Toward the east and southeast the surface of the coal merges into the
general southeastward sloping surface.

If the producing sandstone lens, discussed under the subject of the
Carlinville oil and gas pool, maintains a constant width of one and one-half
miles, its eastern edge may in part underlie the northwestern slope of this

U. S. G
GEORGE (j

0!OD

BULLETIN NO. 31, PLATE IX

I I INois STATK GKOLOGICAL SUKVKV

R B Marshall, Chief Geographer
W H Herron Geographer in charge
Topography by Frank Tweedy, C W. Goodlove.

L. L Lee, and R.M Herrington
Control by J. H Wilson and R.G.CIinite
Surveyed in 1912

H WITH THf • TATI or ILLINOIS

tUNVCTCO IN COOr

4000 2000 O 4000 8000 12000

16000 Feet

13 0 1 2 3 l

3 Kilometers

Contour interval 20 feet.

Datum is mean sea, level

GEOLOGIC STRUCTURE, GILLESPIE QUA

IRANGLK

*prro*'M»Tt Mf»w
OtCUMATION ‘5'S

LEGEND
• Diamond drill
t Churn drill
X Mine shaft
▼ Rock outcrops used
/Contour showing elevation of top Herrin | No 61
jP 5 coal above sea Jevel Interval 25 feel

OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES

103

dome. However, if the deformation of the lowest and most persistent
sandstone bed is as great as appears from the surface rocks it should
furnish a promising location for oil independent of the relation of lenticular
sand bodies.

SOUTH LITCHFIELD DOME

An anticlinal structure of uncertain outline appears to lie about four
miles southwest of Litchfield. In the northeast quarter of sec. 25, T. 8 N.,
R. 6 W. and in the same quarter of sec. 20, T. 8 N., R. 5 W., the
Herrin (No. 6) coal was found to lie at an elevation of 260 feet. Midway
between in the SW. % sec. 20, T. 8 N., R. 5 W., the No. 6 coal was found
in a drill hole at 300 feet, 40 feet higher. Two other intermediate holes
give intermediate elevations of the coal. Nothing more is known regard¬
ing the dome or its configuration, though the surface has been shown
conventionally on the map as grading evenly toward the nearest known ele¬
vation, in some cases several miles distant. The 700-foot oil well in the
NE. sec. 20, T. 8 N., R. 5 W. was drilled in 1906 without success. It
should be noted, however, that the highest observed point of the dome is
a mile to the southwest of this well.

BUTLER ANTICLINE

Outcrops and drill holes northeast of Butler combine to indicate that
the area from sec. 25, T. 9 N., R. 5 W. to sec. 4, T. 9 N., R. 4 W. is
distinctly higher structurally than neighboring areas. To the south and
east of Butler the datum plane slopes away perhaps not so smoothly as
shown at the rate of 20 to 25 feet to the mile, whereas outcrops in Shoal
Creek indicate that there is also a slope to the north or northwest in sec.
13, 14, and 23, T. 9 N., R. 5 W. A small dome seems to be indicated just
outside the area by the unusual elevation of certain strata in a well drilled
in the NE. cor. sec. 4, T. 9 N., R. 4 W. This well was reported to yield a
small quantity of oil.

An anticlinal area is indicated on Shoal Creek by the rise of the Shoal
Creek limestone from 576 feet in the NE. cor. sec. 23 to 600 feet in the NE.
cor. sec. 25, and its fall again in the NW. cor. sec. 36 to 560 feet. Near
the crest of this arch Schaffer and Smathers drilled a hole in January,
1915, which penetrated a sand at about the horizon of the Litchfield
productive sands. It was reported to be dry, but it contained a black,
asphalt-like stain which yielded a faint rainbow on washing. The presence
of asphaltic material under the circumstances of its occurrence here is a
little difficult to explain. It appears that the sandstone in which it occurs,
is a lens lying at the same horizon as, but not necessarily connected with,
the Litchfield sand. It appears also that it was once a repository for oil,
and that the oil escaped elsewhere perhaps in part as gas along bedding

104

OIL INVESTIGATIONS

planes, leaving a residual asphalt adhering to the grains which in the absence
of actively circulating water has never been removed.

The oil well and dome in sec. 4, T. 9 N., R. 4 W., the area of high land
northeast of Butler; the anticline in the Shoal Creek limestone on Shoal
Creek; the Litchfield dome and the dome southwest of Litchfield all lie
along the gentle anticline extending at least 8 miles northeast and 4 miles
southwest of the Litchfield pool.

Oil is or has been present in three of the structural features mentioned
—the Litchfield dome; the dome in sec. 4, T. 9 N., R. 4 W.; and in the
anticline on Shoal Creek where the former presence of oil seems to be
indicated by the asphaltic sand. The presence of oil in these structures
along the anticline points to its possible presence at other places where
sandstone bodies favorably situated and of favorable lithologic character¬
istics coincide with anticlinal structure. It may be said that the entire
length of the anticline is favorable territory, though the most favorable
area outside the recognized domes seems to lie northwest of Butler in
secs. 7, 8, 9, 17, 18, 19, and 20 of T. 9 N., R. 4 W. and parts of secs. 13
and 24 of T. 9 N., R. 5 W.

MACOUPIN DOME

A good shale exposure at the railroad bridge over Macoupin Creek in
NE. cor sec. 27, T. 9 N., R. 8 W., shows the beds to dip about 10
southeast into the bank of the creek. Logs of holes one-half miles south
and one mile west (the Rinaker-Benson well in sec. 27 and the diamond
drill hole in sec. 23) indicate that the Herrin (No. 6) coal is 15 to 20 feet
higher at these points than would be the case if the rise toward the west
were uniform. It seems possible therefore that some deformation may
have occurred in this vicinity and that a possible dome exists at the coal
horizon slightly north and west of the shale exposure. The Rinaker-
Benson well drilled ^4 mile south of the railroad bridge is said to have
penetrated limestone at a depth of 385 feet below the surface and only 260
feet below the Herrin (No. 6) coal, and as reported it contained no sand¬
stone. However, the Mutzbauer well drilled in the flood plain of Macoupin
Creek by the Ohio Oil Company one mile northwest of the bridge, yielded
a little gas with salt water in sandstone. This well was only 351 feet deep
and the sand lies at the horizon of the upper bench of coal No. 2. The
thinning of the Pottsville in the Rinaker-Benson well points to the presence
of a high point or hill on the old pre-Pennsylvanian surface in this locality
which remained as an island at least until the latter part of the Pottsville
.and which may have been covered at so late a date as to prevent the
formation of the oil sands. The dome as shown is not decisively proved,
and it is not certain that any of the oil-bearing sands are present beneath it.

OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES

105

SORENTO ANTICLINE

North and east of Sorento occurs a curiously warped structure which,
nevertheless, appears to be well substantiated by exposures and drill
records. The structure is a sharp east-west fold, open at the west. On
the northeast side the datum plane drops off very sharply, being approxi¬
mately 75 feet lower at Panama than on Shoal Creek in sec. 28, T. 7 N.,
R. 4 W., a distance of less than a mile. To the south the slope is less
steep and to the north the difference in elevation is less than 30 feet. The
structure as an anticline does not seem particularly favorable to the reten¬
tion of oil since, in a continuous sand stratum, there would be nothing to
prevent its escape to the west. Considered, however, in connection with
the lenticular sand beds which characterize the oil-bearing horizon, it may
furnish favorable conditions in lenticular sandstone bodies because of its
steeper slopes and anticlinal character.

OTHER POSSIBLE AREAS

Many small and merely local deformations in the rocks have no doubt
evaded detection, and when the slight deformation which was effective in
producing the Carlinville oil pool and its small area are taken into consider¬
ation, it will readily be understood that there may be many apparently
equally favorable localities which, through lack of rock exposures, it is
not possible to point out.

East of Plainview in the northern part of sec. 10, T. 8 N., R. 8 W.
the beds appear to be higher than elsewhere to the north, east, and west,
the Herrin (No. 6) coal rising to 419 feet in the northwest quarter of this
section. The evidence is lacking, however, to prove positively the exist¬
ence of a dome. It is not improbable also that a slight upward warping
exists west of the Mt. Pleasant church somewhere near the common corner
of secs. 3 and 4, T. 8 N., R. 7 W., and secs. 33 and 34, in T. 9 N., R. 7 W.,
the contour lines swinging around this area suggestively.

At a point one and one-half miles southeast of Taylor Springs in the
center of sec. 25, T. 8 N., R. 4 W., and also at a point one or one and one-
half miles east of Hillsboro (both places, however, outside the area critic¬
ally examined) the contour lines swing as though enclosing dome-shaped
structures, but the positive proof is lacking. Just southeast of Gillespie,
however, although the sweep of the 275-foot contour line strongly suggests
a dome, the drill holes and mine workings demonstrate that the area is one
of low, gentle, irregular warpings and has no well-defined dome structure,
which shows that the curvature of the contour lines may be misleading.

LOCAL PRESENCE OE GAS

Since gas found in the drift in the Carlinville area was the cause of
the discovery of oil and gas in the lower rocks it can scarcely be denied

106

OIL INVESTIGATIONS

that this phenomenon is to a certain extent an indication of oil, though it
is more likely to be misleading than otherwise. It is interesting to note,
therefore, though probably it is not of great importance, that gas has also
been found in the glacial drift at Litchfield, this discovery following long
after the exploitation of the oil. In September, 1913, a well on the farm
of Eggie Rodenbeck in the NW. ^4 sec. 4 over a mile west of the oil wells,
having gone dry was drilled 12 feet deeper. At 53 feet a pocket of gas¬
bearing quicksand was struck. Suspecting the nature of the gas a piece
of lighted waste was thrown into the well, exploding the gas with such
violence as to throw the windlass and planking some distance away from
the top of the well.

O. L. Duncan shortly after sunk a well 200 feet distant on adjoining
property and struck the gas at 52 feet. As this well caved, he put down
another which struck the gas at 46 feet. The original pressure in the
Rodenbeck well was reported to be 7 or 8 pounds, whereas that in the
Duncan wells was only about half this amount. The gas was used in the
houses of the owners of the wells, but in the fall of 1914 had almost ceased
to flow. Gas was also reported to have been found in the drift near
Hillsboro. A hole drilled to prospect the coal in the NW. % sec. 35 is
said to have given off gas in small quantities for several years. In 1909
a hole that was drilled nearby in the hope of striking oil reached a depth
of 650 feet, but only a little gas was found. The hole drilled several years
ago on the Telfers farm in sec. 22, T. 8 N., R. 5 W., by the Producers
Oil Company continues to yield small bubbles of gas.

In none of these wells is the horizon from which the gas comes known.
The presence of small quantities of gas, however, has little significance,
and though oil is usually accompanied by gas, the reverse is commonly not
true.

“KEROSENE” SPRING

In the SE. J /\. sec. 36, T. 9 N., R. 5 W. occurs a so-called “kerosene"
spring which, since it has attained some local notoriety, it seems necessary
to describe. The spring occurs in a small, steep-sided gully cut in the
drift a short distance above its contact with “Coal Measures" shale. The
choking of the gully 30 or 40 feet below the spring has caused the formation
of a putrefying and stagnant mass of sticks, dead leaves, and clay. The
accumulation is three feet or more deep and under normal circumstances
the mouth of the spring is choked and the free flow of the water is pre¬
vented. It is quite saturated with oil that has a specific gravity of 45 r B.
and practically no residue, and therefore corresponds closely to commercial
kerosene. It appears as an iridescent film on the water and is distinctly
more conspicuous when the mushy mass is disturbed in any way.

OIL AND GAS IN GILLESPIE AND MT. OLIVE QUADRANGLES

107

In order to demonstrate whether the spring could be regarded as the
source of the oil, the boggy material was dug out so that there was a free
flow of water from the spring; an auger hole was bored horizontally into
the spring at the point of greatest flow and a pipe was thrust 6 feet into
the bank thus obtaining a source of water quite uncontaminated by the
material about the mouth of the spring. The water flowing from the pipe
was then caught in a bucket especially contrived to catch and retain any
floating particles of oil. After three hours’ test not the slightest oil film
was found in the bucket and the water was found to be sweet and
palatable. The water flowing from the spring was also observed to be¬
come free from iridescent skum. It is concluded, therefore, that what¬
ever the source of the oil about the mouth of the spring it is not derived
from the spring itself. The kerosene, which completely saturates the
diminutive bog, is prevented from evaporating by an annual layer of freshly
fallen dry leaves, and is prevented from escape by means of ordinary circu¬
lation by the practically impervious nature of the pulpy mass.

It is possible, therefore, that the oil may have been held in its present
position for a number of years, for practically the only opportunity for
escape is when the mass is trodden upon or disturbed by digging.

INDEX

PAGE

Adams, C. F., well.64,67

Allendale field, discovery of. 59

oil horizons in.64,65

production in.59,61,66-67

prospecting in.61,67-68

stratigraphy of.61-65

structure in .59,65-67

topography of. 61

Alluvium south of Colmar field. 12

Anderson well. 94

Andrews, Tyler, assistance by. 59

Archimedes in Warsaw formation.. 21

Armstrong, W. H., well. 64

Arvm, M. A., assistance by. 59

Baldwin, A. E., assistance by. 59

Batchtown, Niagaran at. 23

Beard well. 32

Beechville, Kimmswick-Plattin at... 24

Belleville coal, see coal A T o. 6

Best well. 97

Biehl sand in Allendale field.64, 68

Biehl well.59, 66

Birmingham, anticline near. 38

drilling at. 28

Blackburn, W. C., assistance by. 10

Blatchley, R. S., work by.10, 73

Bond County, early work in. 73

Bott well.44, 46

Brachiopods in Warsaw formation. . 22

Breese, Carlinville limestone near. . . 82

Shoal Creek limestone near. 82

Bremen anticline. 69

Brown, Frank, assistance by. 73

Brown County, structure in. 34

Browning, coal No. 2 at. 29

St. Louis limestone near. 30

Bryozoans in Warsaw formation. . .21, 22
Buchanan sand in southeastern field 64

Bunker Hill, topography near. 74

Burlington limestone in Colmar field 22
in Gillespie-Mt. Olive quadrangles 75
Butler anticline.103-104

Calhoun Countv, Kimmswick-Plattin
in ..'. 24

Niagaran in. 23

Cambrian formation in Gillespie-Mt.
Olive quadrangles.74-75

PAGE

Cape Girardeau limestone in Gilles¬
pie-Mt. Olive quadrangles. 75

Carbondale formation in Allendale

field. 63

in Colmar field.17-18

in Gillespie-Mt. Olive quadrangles

. 76.77-81

in Litchfield field. 90

section o f. 14

Carboniferous formations, sections

of.14-17,39

Carlinville limestone in Gillespie-Mt.

Olive quadrangles.82-83, 101

Carlinville oil field, structure in.87, 91-99

Carolyn Smith farm, dome on.66,67

well on. 67

Cass County, coal No. 3 in. 78

Chester beds, absence of oil in. 64

in Allendale field.64,68

in Gillespie-Mt. Olive quadrangles 75

in Randolph County. 69

Chonetes mesolobus. 15

Coal No. 1 in Gillespie-Mt. Olive
quadrangles. 77

Coal No. 2, at, in, or near:

Allendale field. 63

Browning . 29

Carlinville field. 90

Frederick. 29

Gillespie-Mt. Olive quadrangles

. 76, 78. 81

Hancock Count}'. 29

Littleton. 29

Mabel .. 29

Pleasant View. 29

Rushville . 29

Schuyler County. 29

south of Colmar field. 18

structure of.30-31

use of, as key rock.11,29

Coal No. 3 group.76. 78, 80, 92

Coal No. 4 in Gillespie-Mt. Olive

quadrangles . 79

Coal No. 5 in Gillespie-Mt. Olive

quadrangles. 79

near Rushville . 12

south of Colmar. 18

Coal No. 6 in Allendale field.63,64

in Gillespie-Mt. Olive quadrangles

. 76 79, 85, 101

south of Colmar. 17

Colchester, St. Louis limestone near 26

Colchester coal, see coal A T o. 2

Collins No. 1 well.41,42,43

Colmar dome. 43

008 )

INDEX —Continued

109

PAGE

Colmar field, drilling in. 38

extension of.44-45

oil horizon in. 45

prospecting in. 44

structure in.28, 45

Crawford, A. W., assistance by. 73

Crawford County, accumulation of

oil in. 26

Crinoids. 15

Davis, David, assistance by. 73

Denby No. 1 well.93,94

Devonian beds in Colmar field... .23, 39
in Gillespie-Mt. Olive quadrangles 75

Drift, gas in.106

in Allendale field. 61

in Colmar field.13-14

in Gillespie-Mt. Olive quadrangles 85

Duncan wells. 106

Duncanville oil. 91

Fess, Ora, assistance by. 59

Field work, method of. 11

Flitz, Mark, well.74, 75

Frederick, coal No. 2 at. 29

St. Louis limestone near. 30

structure near. 34

Fusulina secalica in Gillespie-Mt.

Olive quadrangles. 76

Gas in drift. 106

in Niagaran formation. 23

near Carlinville.91-99

near Litchfield.87-91

Gillespie, Carlinville limestone near 82

dome near. 105

drainage near. 74

limestone near. 83

Shoal Creek limestone near. 82

stratigraphy near.74-85

topography near. 74

Gordon well . 32

Greenville, oil at. 91

Griggsby No. 1 well.23, 39, 40, 42, 43

Girtyina ventricosa in Gillespie-Mt.

Olive quadrangles. 76

Haake No. 1 well.94,97

Hall wells._. # .93, 94, 95, 97

Hamilton limestone in Colmar field. 40
stratigraphic relation to Niagaran 23

Hammann farm wells. 91

Hancock County, coal No. 2 in. 29

Hare, Mr., assistance by. 10

Hartsook No. 1 well. 44

Herrin coal, see coal No. 6

Hinds, Henry, coal contours by. 42

work by .10, 30, 38

PAGE

Hillsboro, anticlinal structure near. . 105

gas in drift near. 106

moraines near. 85

Hoing oil sand, description of. 24

in Colmar field. 40

structure of. 40

Hoing well, section of. 16

Hood H., assistance by. 73

Huntsville, dome near. 34

St. Louis limestone near.21, 30

Hurd, E. J., assistance by. 73

Ibbetson, E. A., assistance by. 73

Jacksonville, oil at. 91

Jones-Prout-Litherland terrace. 66

Keokuk limestone, in Gillespie-Mt.

Olive quadrangles. 75

south of Colmar field. 22

Kerosene Spring, discussion of.. 106-107
Kerr, J. K., assistance by. 59

Kimmswick-Plattin limestone (Tren¬
ton), description of. 24

in Calhoun County. 24

in Colmar field. 40

in Gillespie-Mt. Olive quadrangles 75
oil in .40, 43, 46

Kinderhook shale, in Colmar field 23, 39
in Gillespie-Mt. Olive quadrangles 75
Kirkwood sand of southeastern field 64
Klein wells.93, 97

Lamberton, P. B., assistance by.... 11

Lamoine Oil and Gas Co., assistance

by. 11

Lamoine terrace . 43

La Salle anticline, influence on oil

accumulation of.26,28

Lawler, Frank, assistance by. 11

Lawrence County, accumulation of

oil in. 26

Lingula .14,15,18

Liston No. 1 well. 97

Litchfield, Shoal Creek Limestone

near. 82

structure near .86, 37

topography near . 74

Litchfield mine, coal No. 1 at. 77

coal No. 3 at. 78

Litchfield oil field, structure in.87-91

Lithostrotion canadense. 19

Littleton, coal No. 2 at. 29

dome near. 30

110

INDEX —Continued

PAGE

Livingston County, coal No. 3 in. ... 78

Loess in Allendale field. 63

south of Colmar. 13

Mable, coal No. 2 at. 29

McCloskv sand in Allendale field..67-68

McFadden wells. 44

McLeansboro formation in Allendale

field . 63

in Gillespie-Mt. Olive quadrangles

.76,81-85

in Litchfield field. 90

McMillen wells. 65

McWilliams well No. 3. 90

Macomb, dome near. 38

Macon County, coal No. 3 in. 78

Macoupin County, coal No. 3 in. 78

early work in. 73

Macoupin dome, description of.. 104-105
Maquoketa shale, in Colmar field.. 40
in Gillespie-Mt. Olive quadrangles 75

relation of oil sand to. 28

south of Colmar field. 23

Marshall County, coal No. 3 in. 78

Meramec beds in Gillespie-Mt. Olive

quadrangles. 75

Mississippian series in Allendale field 64
in Gillespie-Mt. Olive quadrangles

.. 75-76

section of. 15-17

Montgomery County, coal No. 3 in. . 78

early work in. 73

Moore, Roy, assistance by. 10

Mt. Olive, drainage near. 74

stratigraphy near.74-85

structure near. 87

topography near. 74

Mulinax wells.66,67

Murphysboro coal, see coal No. 2
Mutzbauer well. 93

Niagaran formation, gas in. 23

Hoing oil sand in.24 40

oil in. 23

south of Colmar field. 23

Nokomis, Chester beds near. 75

Ohio Oil Co., assistance by.11,59

Oil, at, in, or near:

Allendale field.64,65,66

Carlinville .91-99

Colmar field.42,45

Kimmswick-Plattin formation 24, 34

Litchfield .87-91

Niagaran . 23

Randolph County. 69

discovery of, south of Colmar field 10

PAGE

origin of. 44

prediction of.27-29

production in Allendale field 59,61,66

in Colmar field.42,43

south of Colmar field. 10

relation to structure of.97-105

“sour”. 44

“sweet”.44,46

Orbiculoidea.14, 15, 18

Osage limestone in Colmar field.... 39
in Gillespie-Mt. Olive quadrangles 75

Panama, Sorento anticline near. 105

structure near.86,87

Pearson well.32,34

Pearson, Henry, assistance by. 10

Pelecypods in Warsaw formation. .. 22

Pennsylvanian series in Allendale

field . 63

in Gillespie-Mt. Olive quad¬
rangles .76-85

in Randolph County. 69

south of Colmar’..14—15

water-bearing horizon in. 63

Pike County, source of gas in. 23

Plainview, anticlinal structure near 105

limestone near .83

Pottsville beds near. 77

structure near . 87

Plymouth, anticline near. 38

Pleasant View, Carbondale forma¬
tion near. 18

coal No. 2 at. 29

Production in Carlinville field. 91

in Litchfield oil field. 88

Productus . 15

Pottsville formation, absence of oil

in . 64

gas in. 91

in Allendale field. 63

in Colmar field.18-19

in Gillespie-Mt. Olive quad¬
rangles .76, 77-81

in Macoupin dome. 104

section of. 15

Prospecting in Allendale field.. .61, 67-68

in Colmar field. 44

south of Colmar.27-29 31-34

Quaternary deposits in Gillespie-Mt.

Olive quadrangles. 85

Randolph County, geology of. 69

Reese, John, assistance by. 73

Rinaker, T. A., assistance by. 73

Rinaker-Benson well. 104

Rich, John L., work by. 10

Richmond shale, description of. 23

section of, in Colmar field. 40

INDEX —Continued

Ill

PAGE

Roberts No. 1 well... .38, 42, 43, 44, 45. 46

Ross, John, assistance by. 73

Rushville, coal No. 2 at. 29

coal No. 5 near. 12

Kimmswick-Plattin (Trenton) at 34

oil near. 34

well near . 34

St. Francisville, oil field at. 59

St. Louis limestone, at, in, or near:

Browning . 30

Colmar field . 39

Frederick. 30

Gillespie-Mt. Olive quadrangles 75

Huntsville .21, 30

Schuyler County. 30

south of Colmar.15, 19-21

structure of.30-31,41

use of, as key horizon.11,29

St. Peter sandstone, absence of oil in 40
in Gillespie-Mt. Olive quadrangles

... 74-75

water in .40. 75

Salem formation in Colmar field... 21

south of Colmar. 15

Salt water in Colmar field.28,43

Savage, T. E., assistance by. 59

Schafer, John H., well.64,67

Schuyler County, coal No. 2 in. 29

St. Louis limestone in. 30

Scott County, coal No. 3 in. 78

Sellers well . 97

Shoal Creek limestone in Gillespie-

Mt. Olive quadrangles. 82

near Butler. 103

Shoal Creek syncline. 86

Sian Oil Co., assistance by. 59

Silurian rocks in Gillespie-Mt. Olive

quadrangles. 75

Smith, A. D., assistance by. 59

Smith, C., No. 9 well. 64

Smith, Edwin, well.66,67

Smith, Jacob, well. 67

Snowden Bros. & Co., assistance by 11, 59
Sorento, Shoal Creek limestone near 82
Sorento anticline, description of.... 105

South Litchfield dome. 103

Spanish Needle Creek dome.102-103

Spergen limestone in Gillespie-Mt.
Olive quadrangles. 75

PAGE

Sporangites in Upper Devonian. 23

Springfield coal, see coal No. 5

Stark well . 32

Staunton, Carlinville limestone near 82

Shoal Creek limestone near. 82

structure near. 87

Staunton dome.101-102

Structure in Allendale field... .59, 65-67

in Carlinville oil field. 93

in Colmar region.25, 45

in Gillespie-Mt. Olive quadrangles

. 85-105

in Randolph County. 69

method of determination of.. 11, 24-25
relation of oil accumulation to. . ..

. 11,26-29,97-105

Structure contours, explanation of 85-86
Superior Coal Co., assistance by.... 73

Taylor Springs, anticlinal structure

near. 105

Telfers well. 106

Trenton limestone, see Kimmswick-

Plattin

Udden, Jon A., work by. 81

Urschel & Co., assistance by. 11

Van Tuyl, F. M., work by. 10

Vergennes sandstone, absence of, in

Gillespie-Mt. Olive quadrangles 81

Wabash County, discovery of oil in 59
Warsaw limestone in Gillespie-Mt.

Olive quadrangles. 75

south of Colmar.15,21-22

Water in St. Peter sandstone.40,75

Wear, J. M., well, log of. 38

Weller, Stuart, early work by. 10

White, David, paleo-botanical work

by. 76

Wolf, William, wells. 66