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Elftman, Herbert Oliver A geologic reconnaissance of a portion of the eastern flank of the Diablo Range In Stanislaus and Merced Counties, California 1923 BIBLIOGRAPHIC RECORD TARGET University of California at Berkeley Library Master negative storage number: 03-67.76 (national version of the master negative storage number: CU SN03067.76) GLADIS NUMBER: 184783350H FORMAT : BK AD:991004/FZB LEVEL:D BlT:am DCF:a CsSC:4 MOD: EL :7 UD:030604/MAP CP:cau L:eng INT: GPC: BIO: FIC: CON: ARCV: PC:s PD:1923/ REP: CP1: FSl1: ILC: 11:0 040 CUsScCU 090 SbDISS.ELFTMAN.GEOL 1923 245 12 A geologic reconnaissance of a portion of the eastern flank of the Diablo Range in Stanislaus and Merced Counties, California. 260 $c1923., 300 [ii], 18 leaves :$bill., col. map ;$cl1923. 502 Thesis (B.A. in Geology) --University of California, Berkeley, April, 1923. 504 Includes bibliographical references. 610 20 University of California, Berkeley.S$bDept. of Geology and Geophysics$xDissertations. 690 0 Dissertations, Academic$xUCBSxGeology$y1921-1930 Microfilmed by University of California Library Photographic Service, Berkeley, CA LIST OF IRREGULARITIES, MAJOR DEFECTS, AND MISSING MATERIAL The original is pencil-edited, filmed as is. FILMED AND PROCESSED BY LIBRARY PHOTOGRAPHIC SERVICE, UNIVERSITY OF CALIFORNIA, BERKELEY, 94720 DATE: 08/03 REDUCTION: 10 X AN Ea RE Se eed ED logic neiggance gftern Ilank @ Diablo § &n Stanis- and llerced [é8, Cali~ DIS S ELFTMAN.GEOL 1923 EART fhesis for B. A. Degree Geologic Reconnaissance of a Portion of the Tagtern Flank of the Diablo Range in Stanisleus and Merced Counties, Califomis. HEREERT OLIVER ELFTMAN 1923. DI1ss EL FTHMAN Gee Ll : | 192 2 +3 E A GEOLOGIC RECONNAISSANCE OF A PORTION OF THE EASTERN FLANK OF THE DIABLO RANGE IN STANISLAUS AND MERCED COUNTIES, CALIFORNIA, Newman Wiea By Herbert Oliver Elftman LIBRARY COPY | THESIS submitted in partial satisfaction of the requirements for the degree of B.A Ly BACHELOR OF ARTS 723 in Geological Sciences in the Undergraduate Division College of Letters and Science of the University of California. APProvedeecseceessccsessescensscacessnene »D Instructor in charge. TABLE OF CONTENTS. INTRODUCTION, {.C, sTRATIGRAPEY £/ £ Formations represented Upper Moreno lleganos Tejon Kreyenhagen Kirker(? San Pablo Post-lMiocene Gravels Alluvium STRUCTURE fe, Mg jor structures Minor structures SUMMARY OF-RRSE0Es, | / Mr. INTRODUCTION, eat Be na The area covered by this paper is located in the foothills of the, Diablo Range on the western border of the San Joaquin valley between latitudes 37°7'N, and 37°28'N.; it includes parts of Stanislaus and lMerced counties. The San Joaquin River is approwimetety- ten miles to the east, The area mapped comprises about sixty-five sguare miles, embracing a strip of varying width extending from Black Gulch opposite Patterson to Romero Creek, twenty three miles to the south; it is bounded on the east by ike.vedtey-ef the San Joaquin Cadicy us on the west by the ridge forming the base of the Upper tor eno fav meligm. A stgge line operating betwen Tracy and sno parallels the raylroad and another sfage comyects Patteyson, Crows Landing, Newman and Modesto. There is no brush to impede progress thru the country. Some of the land in the terraced foothills is cultivated while the remainder is fenced off end-weed as grazing ground. There are numerous private roads affording easy access by vehicle to the greater part of the area. The chief obstacle to geologival work is the covering of § alluvium which obscures the Ze formations below the high unterraced hills. North of Salado | Creek the west limb of the Salado syncline is quite extensively covered by slide material from the hills to the west. The territory west of the terrace covering provides excellent outcrops. Robert Anderson and Robert Pack in 1809-1911: their work Wes published as Bulletin 603 of the Survey. the results of EES SQnbiomigy~ The purpose of the present work was to gain further information concerning the geodogy of the region and to reclassify the formations according to the divisions recognized at present, special attention being paid to the Upper Moreno, Tejon and Undifferentiated Miocene of Anderson and Pack. Due to the scarcity of outcrops it was necessary to make a preliminary survey of a considerable area, thereby A preventing very NIE study. Numerous fossils were collected but the greater ih specific determination. It is the writer's intention to follow up this preliminary work with a more exhaustive study of the geology and paleontology of the | B.L.Clark of the University of California for general supervision of the work, Dr.A.H.Elftman for adviee in the field work and the Orestimba 0il Co. and the San Joaguin 0il Co. for facilitating transportation in the field, ToRoGRAREY, —/\ ER —— ’ Topographically the region falls into three divisions: 1) The unterraced hills; 2) The terraced hills; and 3) The San Joaquin Valley floor. The unterraced hills form a belt a mile wide along the western edge of the area. Sheps hey attain jg elevations of from 500 to 1200 feet above sea-level. Jowaras the west they increase in height to .the summit of the fabio Range. Their maturecimw-diasesbed topography is Sntinges by strike ridges and w4eidee valleys. yvouihfai—eapvest. North of Salado Creek these hills have given rise to land slides which cover the west side of the valley of the Salado syncline. To the east and below the unterraced hills are the terraced hills, ranging in elevation from 200 to 700 feet above sea-level. They are characteristically oval hills or oblong ridges with flattened tops inclining gently toward the valley. The tops of the hills are commonly covered by the Terrace Gravels. Altho the general features are not structural, the structure of the underlying formations is assuming control of the topography as manifested in the ridge formed by the basal beds of the San Pablo and by the ironstone reef in the Fig.l. Typical topography. West flank of Salado Anticline between Salado Creek and Black Gulch. Fig.2. Sink hole in Bacon Syncline. The hills at the extreme left are the base of the San Pablo 0 4. Meganos. A few sink holes have formed near the lower contact of the San Pablo halfveyf between Crow and Little Salado Creeks, apparently being caused by landslides. The eastern border of the terraced hills marks the western | limit of they floes of the San Joaquin valley. -She=vatsgi—theoesr Pe-womberdwiiy | flat and monotonous The average slope toward the Sen Joaquin River is about twenty-five feet to the ile, slthe it is greater near the foothills. The evenness of the slope is broken somewhat by dae broad &£ket alluvial fans extending into the velley from the points where the streams emerge on | the valley floor. 7\ Drainage The hills are we¥ drained by consequent intermittent ls al hin ow head bredrg streams 2s an easterly direction. While th treams have built alluvial Ay 49 weld plains in their lower strejfches; by Salado Creek. The streams flow thru these plains characteristically paleed in box-canyons, the Mir sides of which are made possible by the aridity of the climate. Emerging froin the hills the streams turn slightly to the north with the exception of Garzas Creek which veers to the south. Low , broad alluvial fans have accumulated on the border of the San Joaquin valley a] e the streams leave the hills. CR i % \ » B 3 n/ ; i £ h ¢ A of | of, Bae 3 No red oe // wl H ¥ ro » , fhe 110 A ¢ fle oA : 49 pork frees woody will Ye th olan Se Formations represented. A BF Pe t—————— pe or itl \ 4 Anderson and Pack’ Present paper - rr] RECENT AND |Alluvium and Alluvium RECENT AND PLEISTOCENE | Terrace deposits PLEISTOCENE Post-Miocene Gravels (chiefly PLIOCENE Tulare(?) Quaternary) PLIOCENE ? San Pablo San Pablo MIOCENE MIOCENE LUnconformity( ? }—Unconformity Undifferentiated Miocene(position | Kirker(?) not known) Unconformity(?)—t+Unconformity — OLIGOCENE OLIGOCENHY |Kreyenhagen Kreyenhagen b Shale Unconformity(?) ? Tejon EOCENE Tejon ? EOCENE Meganos Unconformity —tUnconformity(?) UPPER CRETACEQUS UPPER Upper Upper lMoreno CRETACEOUS |Moreno ? (Chico Group) (Chico Lower Lower Moreno Group) Panoche Unconformity — JURASSIC(?)| Franciscan Not studied. *U.S.G.8. Bull, 603, Plate III. UPR MORENO. —, <——Fhe oldest formation studied is the Upper loremo. It rests upon the Lower lor eno formetion of Upper Chico age. The Lower Moreno is composed of black clay shale, yellow sandy shale, calcareous Layers and medium to coarse aro sel aapichone. made up of subangular to rounded grains of quartz and feldspar with flskes of biotite ranging in size Zrodlorerseaiphe to a tenth of an inch in diameter. Numerous dikes of sandstone cut -eeness the shale. The Upper Moreno was differentiated from the Lower loreno by Anderson and Pack as a lithologic uml, sates 3% consists predominantly of sandstone in contrast to the shaly character of the Lower Moreno. The contact is not definite but has been arbitrarily mapped where the black clayey shale beds of the Lower Moreno are overlain by gray sandy shale. Above this is a sandstone which contains some pebbles but is not strikingly conglomeratic. About 300 feet up in the section occurs a bed of hard sandstone replete with fossils; the most numerous species is Glycimeris veatchii. On Los Banos Creek, about ten miles south of Romero Creek, what appears to be the same bed, containing Glycimeris veatchii in conjuiigtion with an abundance of other fossils, is suggestive of a possible unconformity. The bed contains angular fragments of material similer to the yellow . J Fi b Figel. Hd E Hl td F: OQuterop of the Lower Moreno and the Panoche formations on the south side of Garzas Creek. The big hill in the center is of Lower lloreno sandstone and black shale; the Panoche sand- stone outcrops on the next hill to the right. Te calcareous shale of the Lower lloreno as well as pebbles of quartz and volcanic material. A layer of broken shell fragments is present there, indicating shore-line conditions. These observations are not conclusive as to the relation of the Upper Moreno to the Lower lloreno, but merely suggest that 7 future work may uncover tangible evidence of an unconformity. The Upper lioreno at Garszas Creek consists largely of grayish-white, fine grained sandstone containing angular grains of quartz and feldspar and small flakes of biotite; when weathered it has a reddish brown to yellow color. Associated with the sandstone is a dark gray fine sandy shale. The sandstone contains small siliceous i scattered sparingly thruout, Near the top is a layer of conglomerate about fen feet thick containing pebbles of quartz and voleanic rocks. On Salado Creek the Upper lioreno attains a thickness of 1,000 feet. At the base is 380 feet of concretionary, medium grained, light gray friable arkose of subangular feldspar and quartz greims with SS biotite, not well sorted; the concretions are ferruginous and range in Sieé-ip-bto-.as diameter Up" se-seven or eight feet. DIlant impressions occur about 250 feet above the base. Above this concretionary sandstone is shaly fine grained sandstone with quite frequent layers of large concretions. The highest bed is a coneretionary sandstone Pig.l. Concretionary base of Upper Moreno resting on Lower Moreno shale; the shale is covered by grass. South side of first hill south 3 of Salado Creek. 3 Pig.2. Concretionary sandstone at the base of the Upper Moreno. South of Crow Creek. Fo AT r ; Concretionary vase of Upper Lioreno resting on Lower Lioreno shale; the shale is covered by gras South side of first hill south of Salado (rect. nd > = io. O Zz bo nd Oo 2 fs ee Oo z < fo = lnm On ne vase Concretionary sandstone at ti Jpper l.oreno. south of Crow Creek. Be twenty feet in thickness in which the concretions reach a foot and a half in diameter. ! Thejage 0f the Upper lloreno is verified ase—beitng—-Oreoiacoouns | and ,-mere—pariionlarl jy-oktee by the fact that it contains Glycimeris veatchii, Opis triangulata and Cinulis Other forms found are Dentalium sp., Turritella sp., EER To ——————————— Placuanomia sp. and Echinobrissus n.sp. — | | MEGANIOS , —, — | oo C_.Resting on the Upper loreno ig apparent conformity is | the Meganos or liddle Eocene. She thickness od-the-Megenes- | between Garzas and Orestimba Creeks is about 1600" feet,” gs | relation to the Upper Moreno is obscure; the apparent conformity and lithologic similarity of the two formations leave the paleontological evidones as the only one for their separation. | On the bas of the fossils the age of the upper formation is dolovmined-as leganos or Middle Eocene, leaving the time interval between the~deposibiom-od the Upper Moreno and Meganos equivalent to Mgrtinez time at least, thus indicating the presence of an unconformity. No £ie}d evidence of this unconformity hag yet been uncovered. The lower part of the Meganos is made up chiefly of light Fig.l. Outerop of Ironstone zone north of Garzas Creek. ni Crossbedding in the lower part of the lMeganos. Gulch south of Salado Creek. gray, medium to fine grained, subangular arkose usually i Shad Cokie tr containing flakes of biotite, commonly small but nExeguenidy 1/16 inch in diameter ,~weedthewming. to-limewite, and some muscovite flakes. Associated with it is some shale, Thais tower.pawt is characteristically crossbedded. The upper part contains more light gray, sandy shale with minute flakes of muscovite, dheo—phedo—tes interbedded with light gray and buff sandstone in layers from a fraction of an inch to many feet in thickness, PRoseNTe od Sonoreiions, nodules and layers of iron oxide #C cer thruout the greater part of the formation. About six hundred feet above the base of the formation on Garzas Creek is a zone of arkose sandstone varying in thickness from twenty to a hundred feet containing several layers heavily charged with iron oxide, predominantly red tho sometimes yellow. This zone can be traced from liustang Creek to Salado Creek, p70 Jecting as, ree above the surrounding sandstone. Immediately below the iron-charged layers are layers of white fine-grained Spills. sendsseme composed almost entirely f angular feldspar grains Oi £.. sland much decomposed into kaolin, Above thie ironsdeme zone the Fe oh J Ll Jeli formation contains abundant’ ‘ferruginous concretions, FreyUENLLY hollow; they are not concettrated in any well defined zone. a Fig.l. Interbedded yellow sandstone and gray shale in lMeganos. Prospector's hole, south side of Salado Creek. Fig.2, Coal mine, south of Salado Creek. IMouth of tunnel at right center; lignite layers at base of tunnel and extending to the left. f a Atl, cb GASP The concretionary Set in contrast with the bedded character of the lowes—~iransgtone zone. Wd erly inilanidd About four hundred feet esbove the base of the lleganos on Salado Creek some streaks of carbonized wood occur, Farther up in the section there are two layers of poor grade lignite, the lower eighteen inches and the upper five inches in thickness, separated by ten inches of carbonaceous gray shale. Below the lower coal bed is a layer of gray clay shale grading downwards into crossbedded light gray and yellow shaly sandstone. Above the lignite is another layer of carbonaceous shale surmounted by crossbedded sandstone. Ff he age 0f the lleganos is determined by the presence of Turritella merriami. Other genera represented are Panope, Leda, Crenella and Placuanomia. ZEJON += C—-The Tejon overlies the Meganos but breir-reiations-have not-begn devepmined~ginee the presence of the Tejon was not recognized before the identification of fossils after the completion of the field work. These fossils occur in a layer of quartzite which can be recognized at three places: 1) South of Bennett Valley; 2) South of Orestimba Creek; and 3)-Between Orestimba and Crow Creeks. The Tejon and Meganos are mapped together with the probable lower contact of the Tejon, located above the concretionary sandstone and below the quartzite, indicated by a line. The quartzite in which the fossils occur consists of quartz grains in a quartz cement and is sprinkled with grains of a black ferromagnesian mineral almost entirely altered to a greenish yellow aggregate, probably epidote, Higher in the section the sandstone has a cement of yellow calcite. Between Orestimba and Crow Creeks the quartzite is underlain by a light gray, Sots sandstone and a foot of white shale. In Bennett Valley a fine, gray, sandy shale outcrops about fifty feet | stratigraphically above the quartzite. The thickness of the Tejon is estimated at five hundred feet. Pell. The age of the Tejon is determined by Cardium brewerii (large variety) and Turritella uvasana. SRETENEACED ws id BE The Kreyenhagen formation overlies the Tejon with apparent conformity of dip and strike; the contact has not been found in the field. A large part of the one thousand feet of Kreyenhagen is composed of diatomaceous shale,which is chocolate brown underground but is white at the surface. Especially in the lower part of the formation the shale is interbedded with light gray, muscovitic, arkose sandstone. The basal part of the formation is not exposed. The shale is traversed by numerous dikes of sandstone standing at a higher angle than the shale; PLATE VI. Fir. Fig.l. Sandstone dike in Kreyenhagen shale. The shale dips gently forward and to the right while the dike is nearly vertical. Quarry west of Crow Hills. A Fig.2. Sandstone interbedded with Kreyenhagen shale. Quarry west of Crow Hills. this sandstone is similar to that interbedded with the shale. The age of the Kreyenhagen cannot be determined from fossils contained in it; its Oligocene age is indicated by its continuity with the Kreyenhagen Shale of the Coalinga district and the fact that it underlies the Kirker(?) formation of Oligocene age. — «The fossils collected from the Kreyenhagen are casts of - A PADI EH Vs al Pecten peckhami, Acila cf, muta, fish scales and fish vertebra. KIRKER (2). Resting unconformably on the Kreyenhagen is the Kirker() formation. Between Orestimba and Crow Creeks the contact is exposed; the Xirker(lies upon the eroded surface of the Kreyenhagen and contains angular fragments of Xreyenhagen shale in its lower layers. The KXirker(/reaches a maximum thickness of four hundred and fifty feet south of Orestimba Creek in Poverty Flat; it is not known to outerop south of Bennett Valley. The basal beds are of clayey sandstone, containing some biotite and muscovite / and iwmedwding. fragments of the Kreyenhagen shale. Above these beds is a well=-washed, yellow, subangular sandstone. Higher up in the formetion in Poverty Flat there is a bed of white clay Fig.l. Kirker(?) exposed in cut. Poverty Flat. C Fig.2. Contact of Kirker(?) on Kreyenhagen shale. South of Crow Hills, containing plant impressions. The upper part of the formation consists of a yellow sandstone. The beds described as Kirker(?) are considered to be Oligocene in age on the basis of numerous casts of Aclla muta They are further tentatively correlated with the Eirker formation north of Mt. Diablo on account of the stratigraphic position immediately above the Kreyenhagen shale. These beds were described as Undifferentiated Miocene(?) by Anderson and Pack, but they did not state their reasoms for this correlation. Few fossils are found in the Kirker(?); Acila muta, Pecten 0A AI peckhami, Thyssira spe. have been determined. Tlant impressions a occur as mentioned above. SAN PABLO. The San Pablo succeeds the Kirker(?) with an unconformable relation. Between Orestimba and Crow Creeks it cuts off the Kirker(?); to the north it truncates the Kreyenhagen, resting on the Eocene on Little Salado Creek and to the north of it. On Salado Creek the contact is exposed, showing a marked discordance of strike and erosion of the Eocene surface before the deposition of the San Pablo The greater part of the San Pablo - 4 “3 £ 2 fa wt a Jil Any he FIT { (L/ o 3 / LV } Js it bh v [re o£ Jan 7 LAM A A # Fig.l. Outcrop of San Pablo in Poverty Flat. The bed at the left is the indurated bed near the base of the formation; outcropping above it is a layer of tuff. Fig.2. Same indurated layer as shown in Fig.l. South of Orestimba Creek. 14, is hidden by the Bgst-liiocene Gravels and the Alluvium if its \ exposure to the north in Corral Hollow is any indication of its development in the ¥egion, as only a few hundred feet is expo sed. The San Pablo consists of tuffs, conglomérates and coarse sandstones. Between Orestimba Creek and Little Salado Creek the base consists of about twenty feet of coarse, sharply angular, ill-sorted fanglomerate which is well cemented and iron stained; this grades upward into a finer conglomerate with rounded pebbles. Above these basal layers are alternating layers of sandstone, conglomerate with a sandy metrix and OQ white, cream-colored and blue massive tuff. The sandstone is prevailingly coarse and quartzose. In the creek bed one mile southeast of the Crow Hills there is a thin bed of white diatomaceous shale in the San Pablo. South of Orestimba Creek a bed of sandstone near the base is indurated and stands out as a reef. The conglomerates are not well sorted and contein fragments ranging in diameter up to four or five inches, A ® was correlated with the San Pablo by Anderson and Pack™ because The San Pablo has afforded no fossils in this region. It it is apparently continuous with the San Pablo of Mt.Diablo. ——E *UeSeGeSe Bulle 603: D.96 POST-MIOCENE GRAVELS® (Chiefly Quaternary). The formations younger than the San Pablo are typical stream deposits, consisting chiefly of conglomerate with some sandstone. The pebbles of the gravels are sub-angular to rounded and consist of quartz, chert, volcanics and sandstone. Some silicified wood is also present in a few places. These formations were divided by Anderson and Pack into the Tulare(?) of Pliocene and Pleistocene(?) age and the Quaternary Terrace deposits. The Tulere(?) was separated from the Terrace and Alluvium chiefly by the fact that it was the last formation to in the orogenic disturbance. When it is considered that the usual dip near the outerops 0f the Post-iliocene Gravels in the area under consideration in the present paper is about ww, it is apparent that this is too close to the angle of deposition of fluviatile deposits to enable a satisfactory separation to be made on that basis, Due to this and to a lack of opportunity to search for some other distinguishing feature, whatever Tulare(?) there is present in this area is mapped with the Quaternary Terrace deposits as the Bost-Uiocene Gravels. Anaeravu and Pack state that the San Pablo apparently grades up into the Tulare(?). In a trench dug on the south UeSeGeSe. Bulle 603: PP 101-102. Fig.l. Hill south of Salado Creek. The flat top is due to the Terrace gravels. flour side of Bennett Valley sm—unconfermiiy was discovered dupdag the-present-work, a fine, yellowish sandstone dipping slightly to the northeast lying on a large boulder of San rablo tuff. The age of the sandstone is uncertain: it may even belong to a later division of the San Pablo; but it at least suggests the possibility of an unconformity between the San Pablo and the Tulare(?). The Terrace deposits occur at various heights from the present stream levels to about two hundred feet above them, The outer foothills have characteristically flat tops gently inclined toward the San Joaquin Valley and covered with Terrace Gravels almost identical in character with those of the Tulare(?). ALLUVIUL. The Alluvium is the more recent continuation of the deposits of the streams emerging from the hills. It is a continuation of the same, processes which formed the Tulare(?) bi and the Terrace Gravels and which are still active.,. i i § § ! i i ! / i & 17. 4 ] a ray 5 oh 4 £4 wae A HE f A. pe 7Y / hq i / ig / JO tin SRA ni STRUCTURE. . . ....—""£} The major structure of the area is that of a homoeline dipping eastward at angles of from 50° in the Upper lioreno hills to 5° in the San Pablo at the edge of the San Joaquin Valley. South of Gar zas Creek the prevailing strike of the homocline is ¥40°W; between one and two miles north of Garzas Creek the strike changes quite abruptly to KX 10°W, continuing in that direction for twelve miles; at Salado Creek it becomes 0 NN 20 W and a few miles farther north it resumes its former course. Upon this major homoclinal structure are superimposed minor crenulations consisting of four plunging anticlines with their complementary synclines. The axes of the anticlines and of the Salado syncline as well as the sea level contour of the base of the San Pablo are shown on the areal map. The anticlines all agree in plunging at an angle of 7°, the three southernmost plunge away from the homoclinal strike while the northen or Salado anticline is parallel to it. As fr be seen from the structure contour the folds, with the exception of the Salado anticline and syncline, are broad with gently sloping sides. The Salado anticline is more acute, dipping 50° on the east side and somewhat less on the west. i 33M LL 4 NIROVoOr RVS "ANITIOILANY 0AVVS "ANIMO NAS O0QY VS SECTION -B 2,600. Scale: mh NIM I¥ vEWI1S3a¥0 k el Q i ar na od a, 3ANCZ 3NOLSNOMN SECTION CD é2,560 Scale: The synclines are marked topographically by valleys: the Garzas, Orestimbs and Crow synclines are situated in the valleys of those creeks; the Bacon syncline, to the north of the Bacon anticline, is marked by a smell valley; the Salado syncline is associated with a valley south of Black Gulch. Minor structures. ) C The Tovar antivline is broken by a fault a mile and a half south of Orestimba Creek, The strike of the fault is N 38° E; pthe northern side was downthrown, the throw being 40 feet. The Crow anticline has a sharp flexure almost passing into a fault situated near the axis of the fold. | : This flexure strikes N 65° E and may be taken as representing the axis of the anticline. SUMMARY o._ wei Besides providing a basis for future work the most important results. of this preliminary survey aa 1) The division of the Tejon of Anderson and Pack into the Meganos and Tejon. 2) Recognition of the Oligocene age of the Kirker(?) formation, described by Anderson and Pack as Undifferentiated liocene(?). 3) lore detailed study of the structure. * DOCUMENT FILMED IN SECTIONS pt TOPRPOG en DEPARTMENT OF THE INTERIOR S FRANKLIN K. LANE, SECRETARY oN STATE OF CALIFORNIA LY % U.S. GEOLOGICAL SURVEY WAR DEPARTMENT : WILLIAM B. STEPHENS, GOVERNOR = GEORGE OTIS SMITH, DIRECTOR CALIFORNIA 2 CORPS OF ENGINEERS, U.S. ARMY W.F MCCLURE, STATE ENGINEER : 3728 ris’ sréso) 10’ 5 ORESTIMBA QUADRANGLEWY § : R.8E. 5 (Westpore aiaao / R.9 E. 200, a i * TT 3730 7 & 13 i or AREAL GEOLOGY. LEGEND. Alluvium Post~=Miocene Gravels (chiefly Quaternary ) : : Axis of anticline San Pablo. i (dotted where uncertain) Kirker(? —¥——-— Axis of syncline. Sea level contour of Kreyenhagen Soccsestet base of San Pablo. Probable lower contact of Tejon. A—————B Line of section. PLIO .& CRET. EOCENE OLIGO.MIO.GQUATER. snsse* sass oes (Mitchell School ToT Tal Tg a de S| | te 6 - oOo - pt - © gt, bi Bil 31680) TUR 27. . ‘ . RE: [Westport aieso i Haight 114 7, . . Pa ) 7 g TT ET sen | Vanor en NN ) 7 AnuAl GEOLOGY. nn Sav dve id LEGEND . mrs v Ch he da ® Alluviunm A LLIC. U rost-lliocene Gravels (chiefly Luaternar:) Co } ~ vor vA i: > anticline Lan Palo. } wnere uncertain Xirker(?) 4 - — { - “oe —h { MVS Lh LI Kreyenhagen Cscoecssy0 es =z 0 Tejon eteeceeinenn lleganos LOCH A Upper loreno " r Lower lloren IRIN C AH on 0 “ww 7 EEO) (Mite oll School i tren a ~ = ] > ~ = QQ oy > ~ = a 3 = Z, Q z = = 7 < 3 “ em, Orestirba Pk 2073 Ne - 21680) (Gustine Canal daa 22 EE theta aed wren ney re *6 pel Tag : Pat enseee ,, Brush tte SH Mt Cottonwood . School P v f (eedte nuobiuy) ° Tn —— 4 d—" & 9 © | i wendy a L P A EY w F< j 3 Vi 2 b 1 ; ’ T - 3 aA i « —- : 2 i Pe = / . i & A i : { L Nr I of i i . ' wt ra mE, - 4 | : i o Q # + a : ] EE { _ 42 - i ™ 4 ' 2 5 eg, : . i NH be 2 : ® N i i [ i [ ob rm i€ befanemmn tuned sana panning n= : i i ye TN A i Cee fo i : i 4 n TT » i > S$ af ee \ ry h : ie hy punssapmsenald it - : 0 = Bie g a i mit { ° Te | s, hana 7 a A | . 7 ; Vd a Na : i uly L~ 3 mm, yy OZ fens -<. 2) RN / = TIA os / ~~ f 4] i { { Ader} i .. N —"" vam a. Php L Pood - a, i / en an’ A - a wen anungd®® “ ” 2 mii a Ee si, ra ut joi per { 5 or ned 7 fi 4 pr > we’ | MGT 7 7 7 emmm®? 2) i Ci 2 A NAA { EI & ™S T Aimy C 7 TONY SQ BN \ ER \ <3 0D 2 2 \ = } 4; 55 77 ma = = ro 228 I~ x Cans Ne ik TRARY. Pa UA IN IP } > - R : § A 2) Ri RTE. 2g Se QQ Fx a) yd ¢ 2, iastF VEEN ATR CT) fo AAA TONER JRE 7 Healt QL \W js IN JANE ER AN rr ENGRAVED 1918 BY U.5.6.5. bs RA LE CAN ROR ATRG b in 2 oN Edition of 1920. 0 eS HLIMON 3NHL a Miles > 7000 Yards Scale #3806 3000 LP & o.[ne8 Davis] N.E.B. Wilso: TPP dif 2 L £3 z F a3 wi be Zz 20 £ch 00 292 $23 Pll it” 1 ss 2 £6802 scat L.- 0@ Qh cd ow 2a. clodo Oa>3ZSeh @ 8 ~~ PELs Ee = ou = 888 Ogu ~@w == 8a BOC > jc £2128 ne 28 ax 2% 0 p= L 07 8 2CgQf¢ i 000% 3 Laan ; °oRS8 xOFa ! “ane, 5 Kilometers APPROXIMATE MEAN PACHECO PASS ? Sriram ons wel DECLINATION, i918 SURVEYED iN COOPERATION WITH THE WAR DEPARTMENT AND THE STATE OF CALIFORNIA. Contour interval 50 feet. (Gilroy Hot Sprin vert A A ASN AY LAE RN Lah ~ : & { AAifis¥d Rauch a J ee QO ? La . \ u 7 ye Ne Nes, 20 N L/ —y LO} “5 OOM C CSpririg A ) os as #7¢ ( Basalt Hill Fesan yn » i” ERR EEN \ i Lf s Levi saal ~ | /\ Canal Sche O nV School (Ireg omar i hief Geographer : | ¥ og Pr Geo R.Davis, Geographe harge STD — & oo Topography by E FP Davis, T P Pendleton, N.E Ballmer, Roscoe Reeves, KR. M Wilson and L.H.Cor nely Control by F. Biggs Roscoe Reeves,and C.F.Urquhart ; 100 500 o 1000 “OOO 7000 Yards . == _— ey ey —— 2 Oo EHF EY ra Ey 5 urveyed 16 and 1918 1 2 0 5 Kilometers SURVEYED IN COOPERATION WITH THE WAR DEPARTMENT HEE EEE os AND THE STATE OF CALIFORNIA Contour interval 50 feet. Datran is mean sea level. } LI + Miles Vs V3 APPROXIMATE MEAN DECLINATION. 1918 PACHECO PASS AIAVHA ONIAADTAd 40 IIV.LAY END OF TITLE