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Seek te aes SB ie Ss Ct : vi ‘ A we & 1 -—. fa | s ~! dL Ph bottled he} OO ws... wry a ebay Ore yee ag Pet hela Coe ea eaten See MN yun rtnens, : nvr, nitty vty TN Di Vere mcloiie Uyecss Wi SOE SNA ac Lee Mae ‘ rs vs bi a ich Ah A Jey Me ~wv yee” | Wo BE Geie ee pecees| cae LL MA AG id Wie “%S go" ‘yy we vga be may bey We tf cam Mere mer tt ae EUTE my, St wee Sy GE era oc eit LUISE ew, copenett” ' wy Ay ar he iM 1s 8 » wry ee " MeL a eo reaiy WW ove yWtoy' ‘ be) hb Wyse avapro" MN qndflnwy Tomes earns vo ov seaue } eee api wersewetenl red [pd vduweeveud wel y nN NTWee Pet ae PL Mee sess aer wee use gets b| Nig Pad ae Mi a ts og 8 SY ec NN ea : a=" & ETL LL] Bees Puen on mS Ee fee Vo Viv"! a: we ices svat | | aan ss Tee Hieccce eeveavrntt | vvvwdily pahannsere e: wipers: weft cue bbb LY Plt ets kota ut Ret oT wUy EDSyegeee SEE pr arnepenetnttt saeeha a psn baagped i Bn’ Wy yeti owe we | si Mi vier ees {8 mw ive wits) ah SE aiudiehioiiittt set tt = 2S gs 63 oe Gee : 3 “Ry are yo r% bt caiaaalllies a ; Wood 3 hh wes ad, Won i Wain Tal HEY i PEPE 1 nee SSE, | psa wad oe Te aunt { SAY \ We l Ma AU Jd ge’ | Wi beep eee SS : ve hen CSS GS ae tedyh. e Nooo 4.4 Aa ft ; tee” weru Se: : ‘ ett acmiriae cl ze 1 vue Stary s e ws ‘ j Mpc enyeee eseEe ide ei ge ee ape POTS te hal {<> wots we 1 | yaa “VWvily Sit MALT Dal eh del hii WL \ SE ee zew er ta eee" Lida his Wedge tae Wy ey 3 a | J ~ Ween oe ee bs i Bou (90 we te, Oe i= Us ba Ta aes ! waedterey rit Ska ae | Mn oe: sve raeerts Amt ee cog eayt Nba 4 as, “wre, oe Seay bata atind ey mete} a tt tae ow 7 hy ; Z s< = 2 q ¢ ‘ i : w + Were he | i 1h M ny yeteerean# : Ven! NPPAver reese rssyrysy MA he Lat Y TE bate ='eu twee | : | | 5 , a . : PF a ret se Pid th Te Newlass Mi vn vn, neeiey ye evens 100 ayaa! OL A i wt LAST Pt Sy ae nA SI rd “a . tee NAA we f eeut RASA ore ok AAA PeperaeTteRt nie ~~ Serer eee eV hw " Mite Ht BY “eye Sieg he Nee ALL be: Wy, eststee eee hig vee Ny itee TOS pes RC Bite tt te | wy Ptr uy ¥ We. vy . a = bi \ . ma Adie ~dw , > ; ‘awe . , see Weve set ihe wo bathe I yyy ppd ye ont : v 0) a Y ay vv, SUreTUNet et itn 7@ sib . Sa5” a ee ld asi v- Ad | AA | ’ ; rot T Ld BS aie A ~T | Vy — he » areal 4 a: rth See eet 4 Fe k groves, y"- MAT Th aw 1 be | fe hw we ve Me aye ieee tt oie we. Wc AU aie | SY al mY inte cent agyeetys ayll Ot GEDDY, 1 DD bl A ane aN LA TTS rid] Tas ¢ y7y q i aed myth ¥ oD vy. whey Sd NDT hos av TN ue never i Vv | me were vee vevrioeie tier TTT 28 Pe Udi. Pe ee Uahavey Ula oetN eve a ye § ee PRES Sam § ome ~~ (raya ee ipa ¥ ; . aay Mai se: rs Hf Ne i? cee M ae, tl an i im) hig AM 19 i pin - oo i Y . » lilt ia. | if; t Wen us Lett 1) bal is : neo wis ph : ~ a uk me > i Vre | (Vale Baan 4 7 ih TE i a a yn me a ae sid y ra oe Deeiaas : ay my as ml - y 0 0 Fok 7 " an Me i y ot r} at : oh : 7 > ane rh ie i, ha Me 1) ve ‘4 fw “Ti. x ” Nhe Pe ie ae 7 0) ed) va fl ' ie a mT iv i sae r.. 7 ny 1 ty i. om at ieee mye | ne | i ¥ 7 rt ” : ay Hy : [° (NRE V2a 0 oa cp a Ms ay Ne an ae My aR ca oe Bat ai Wea Pull! 14) ye th yin sd ; j a sigh a ‘a : iM bs / C153 A ie) awe ow ‘4 S7 University of California Publications in GEOLOGICAL SCIENCES VOLUME XIII 1921-1922 EDITOR © ZN ANDREW C. LAWSON de JUN 71924 *) 269716 y UT yy a \ 4tional Muse~ UNIVERSITY OF CALIFORNIA PRESS BERKELEY, CALIFORNIA CONTENTS PAGE No. 1. Lower and Middle Cambrian Formations of the Mohave Desert, by IMEC OMEIWieg Clare kae caresses serres evs ctuer scot css scsSecsetsace ure suaevaset scot Seaver veenes Se cnae dees 1 No. 2. Notes on Pececary Remains from Rancho La Brea, by John C. Miermameand i @hester S60 Ck: etc. ce tenses oe sc crease nn oat ceeesteeeeeeeeateesecacs 9 No. 3. Note on an Hipparion Tooth from‘ the Siestan Deposits of the Berkeley Hills, California, by Chester Stock -.......0..20..220222:22:2:000-++ 19 No. 4. Pinnipeds from Miocene and Pleistocene Deposits of California. A Description of a New Genus and Species of Sea Lion from the Temblor together with Seal Remains from the Santa Margarita and San Pedro Formations and a Résumé of Current Theories regarding Origin of Pinnipedia, by Remington Kellogg .................. 23 No. 5. The Briones Formation of Middle California, by Parker D. Trask.... 133 No. 6. Geology of the Cuyamaca Region of California, by F. 8. Hudson........ 175 No. 7. Genesis of the Ores of the Cobalt District, Ontario, Canada, by EAS fore CLMBES ses Wil G Tia curiae eee cree ace ck cane occ eft See cere se cece Sessa Les coven hee cea 253 No. 8. A Marsupial from the John Day Oligocene of Logan Butte, Eastern Oregon, by Chester Stock and Eustace L. Furlong ...........0.......... 311 No. 9. Geology of San Bernardino Mountains North of San Gorgonio Pass, oye DN AMOS! ADL erie N/T Oa) eee Se ea ee 319 No. 10. New Species from the Cretaceous of the Santa Ana Mountains, California, by He W.. Packard) <....2:2:2..scscesccsscctetsiee.ssiescessectecesstecssacesceves 413 TIN OF THE DEPARTMENT OF LOGICAL SCIENCES | ; December, 20, 1921 ol. 13, No. ¢ ¥ Ue i ae ee et ER AND MIDDLE CAMBRIAN FORMATIONS __ OF THE MOHAVE DESERT. XN ) ~ > oy ca BY _ CLIFTON W. CLARK f ' UNIVERSITY OF CALIFORNIA PRESS | BERKELEY, CALIFORNIA RNIA PUBLICATIONS pee a yauiian Lg py) Ne GEOLOGY. —ANDREW ©. Lawson, Editor. Price, volumes 1-7, $3.50; volumes 8 an 17. . Is the Boulder ‘‘Batholith’’ a Laccolith? A Problem in Ore- Genesis, es ae . Note on the Faunal Zones of the Tejon Group, by Roy E. Dickerson ...........-..- . Teeth of a Cestraciont Shark from the Upper Triassic of Northern California, I . Tertiary Echinoids of the Carrizo Creek Region in the Colorado Desert, by William . Fauna of the Martinez Eocene of California, by Roy Ernest Dickerson ............ . Descriptions of New Species of Fossil Mollusea from the Later Marine Neocene o: . The Fernando Group near Newhall, California, by Walter A. English ....... See . Ore Deposition in and near Tneuciee Rocks by Meteoric Waters, by Andrew c . The Occurrence of Tertiary Mammalian Remains in Northeastern Nevada, by Tohn . Remains of Land Mammals from Marine Tertiary Beds in the Tejon Hills, Cali: . The Martinez Eocene and Associated Formations at Rock Creek on the Western . New Molluscan Species from the Martinez Eocene of Southern California, by Roy . A Proboscidean Tooth from the Truckee Beds of Western Nevada, by John PL . Tertiary Mammal Beds of Stewart and Ione Valleys in West-Central Nevada, nee a Physiology, and Zoology. oo $5.00. Volumes 1-11 completed; volumes 12 and 13 in progress. A list. volumes 1 to 7 will be sent upon request. wes 3 “VOLUME 8 — Co A WSO. ~ncseeceentsaccesseaponnsoe a Sanccnagpe eaSco coe cs eeet etn ee Aa an Harold: ©, Bryant. tj. 02.5i ine eee en Bird Remains from the Rleistocene of San Pedro, California, by Loye Halmes M 5 We ROW) one. ssncnnsdeluteseee doen: Wiens enketbonstetiaecstesccsdzest re aA Ne ae rr % California, by Bruce Martin’ ._2...4 200-2 TB WSOD, § be ncoces-ocesenadebapsncecencetecnnnon asoccescciv oss oes kepacent alas aM aeEs cee eee tiene ae ar . The Agasoma-like Gastropods of the California Tertiary, by Walter A. English... 15 . The Martinez and Tejon BHocene and Associated Formations of the Santa Ana Mountains, by Roy H.. Dickerson ©.:.2.2:c0i-:-015. cece cee tec crecctnspen ot GSM erria mi £.....200-1-odacnce encase scien bcopeed sane ot Sten geteileae Teac dene ce eee fornia, by John C. Merriam... cs. ic cece esc scenes ener eee a hs Border of the Mohave Desert Area, by Roy H. Dickerson 2.0..-t.-ccccccsesscee reese Hy. Dit eerson’ .sosee cine c sien sot wane secon e eect ale setae we nnnget Sennen etc cg SRR Onnee at ae Buwalda John P. Buwalda —..-c.:-..-cctennecsesa neediness ee er . Tertiary Echinoids from the San Pablo Group of Middle California, by William s “4 WE ROW. wscneccokeceseecseteccchoceucchss-tegute/ SBR we ec ek et le 21. An Occurrence of Mammalian Remains in a Pleistocene Lake Deposit at Astor Pass, near Pyramid Lake, Nevada, by John C. Merriam ...02.2:0.20..22-cenpete 22. The Fauna of the San Pablo Group of Middle sue ae by Bruce L. Clark oat VOLUME 9 ay 1. New Species of the Hipparion Group from the Pacific Coast aud Great Basin Pace nees of North America, by John OC. Merriam <2... 5 icici t ccc ne renee 2. The Occurrence of Oligocene in the Contra Costa Hills of Middle California, Bruce Da CU ats ? os. Beseens = actansieteecneneeevanpsceccte nd tenantnctn etnies 2p ten aa Bs 4. 5. 6. pee ae Formations in the North Coalinga Region, California, by ieee OL Nomiand i226 oe re a a mena ee oe ‘7. A Review of the Species Pavo californicus, by Loye Holmes Miller .... cr The Owl Remanis from Rancho La Buea, by roe Holmes Miller .. UNIVERSITY OF CALIFORNIA PUBLICATIONS BULLETIN OF THE DEPARTMENT OF GEOLOGICAL SCIENCES Vol. 13, No. 1, pp. 1-7 December, 20, 1921 LOWER AND MIDDLE CAMBRIAN FORMATIONS OF THE MOHAVE DESERT BY CLIFTON W. CLARK mna CONTENTS ee BT Erarts TsO CUUL tel Oa renee erasers teeters a ee ess Cee OS ee nero ee eee ee end eos ewe Sse es eeencee 1 Occumren Cero tet OFM Abi ON Shes < tases eae ee oS es a Se ee eee Sek Sonn Secs seca ta eeeee 2 (Geoloorcaile atone wrcn tf ccetcete cece ccenes cecal cs fatten ooys ween Seca. vovsee cance Cecueey ites sccacecapess Slescsarves 3 Rhemmvasionuok "MATING WaAteYS, 22.22. 2-ico loca oe eee ee es cece cee nn Sonos cence es icccceeeceee 3 TESCO sae olf aia a fon fi 0 yt ee eae TS NR ah 3 Lower Cambrian 3 Middle Cambrian 4 War OnRONOUS seen occ: Se csse es eRe eked Bese Ace ccce es eese nce cee Ne : 4 BB TAIGEOMWOUNtAIN: ‘SECTION <-...2.-cucccceec00eecaecceecenedenceccecne-seeeeceeeenceereeeedsneeeeeeeenen Pee 5) TEMS URTEVENG), © eee oe OP I ee ee USE 6 BIB OnW ie Yam CUYD oN a Tigges wee see ose ee a ec see eee eae aces aaeeveceee 6 Min Gilen@ amr anipscsssttan-es heen. So Ne eed cence eee ee PE ee Be ee 6 (ans OTIE TOUS tee atrees ea eee eee een eee, ee ce ee eS ha eee 6 Wornnelatilonpeee <0 arn 2 ie ee Se eee ts ee ke ee ete Uf INTRODUCTION Paleozoic sedimentary rocks are exposed in Bristol Mountain! in Mojave Desert near the town of Cadiz on the Santa Fé railroad, about 100 miles east of Barstow, California. Darton? first described these rocks in 1907 and again in the Santa Fé Railroad Guide in 1915.* In 1915, Mr. O. A. Cavins, a student in the University of California, while studying the geology of this region, discovered a shale bed con- taining Lower Cambrian fossils. From the study of a small collection made by Mr. Cavins the writer became interested in the region and spent about two weeks visiting various exposures and obtaining a collection representing the fauna. Weeinetiron Mountains referred to by Darton in the Santa Fé Railroad Guide for 1915, will be called in this paper Bristol Mountain, the name given to the range on the official map of San Bernardino County. This map also gives to the lake at Amboy, 14 miles west of Cadiz, California, the name, Bristol Lake. 2 Jour. of Geol. vol. 15, p. 470, 1907. 3U.S. Geol. Surv. Bull. No. 613, Part C, Santa Fé Route, 1915. 2 University of California Publications in Geology [Vou.13 Bristol Mountain is a long, low range of hills or ridges composed of igneous and sedimentary rocks representing various geologic ages. The sediments range in age from Lower Cambrian to Carboniferous. The mountain is about 20 miles long and from 1 to 3 miles wide, the highest peaks reaching an elevation of 1000 to 1300 feet above the desert plain. It is situated on the north side of a great dry lake basin, the lowest point of which is near the town of Amboy. Just south of this town there are extensive beds of salt and gypsum which were left as a deposit when the lake became dry. How large this lake was is not known, but the country slopes toward the saline deposit for many miles on all sides except the southeast. Sedimentary rocks very similar to those in Bristol Mountain are present in a number of other ranges in this region, but most of them have suffered more intense metamorphism. The character of the sedi- ments and the fauna contained in them indicate that these formations may be correlated with those deseribed by Darton in the Providence Range to the north and also with those of the Highland Range in Nevada. The Providence Range was not visited owing to the limited time allotted to the work. The study of the section in Bristol Moun- tain, together with more detailed collecting in other exposures of sedimentary rocks in this region, should add many facts to our knowledge of the Paleozoic of the Great Basin. OCCURRENCE OF FORMATIONS The writer has visited localities in the Ship Mountains, the Marble Mountains, and the Clipper Mountains, but no fossils were found in these ranges. All the fossils referred to in this paper were obtained in Bristol Mountain. Paleozoic strata occur at two localities in this range. At the southern end their exposure extends to the north- west for about two miles to a point where they have been entirely stripped from the underlying granite by erosion. From this point granite and Tertiary lavas make up the range, forming low rounded hills for three or four miles toward the northwest to a point where the granite is again overlain by Cambrian strata. Here the exposure of Paleozoic rocks begins just north of a deep cafon which transects the range. The rocks extend toward the northwest overlying the pre- Cambrian granite for a distance of about three miles, beyond which they have been cut off abruptly by a large post-Carboniferous granitic mass. Although the range was not visited farther north, the writer was informed by a resident of the district that the whole of the northern end is composed of igneous rock. 1921] Clark: Lower and Middle Cambrian Formations 3 GEOLOGICAL RELATIONS The sedimentary formations in Bristol Mountain rest on pre-Cam- brian granite and dip at a high angle to the east, passing under Tertiary eruptive rocks. They comprise quartzite, sandstone, shale, conglomerate, and limestone in a conformable series. A repetition of this series across the strike of the formations has resulted from local faulting, which is very common; and step faulting is well exemplified at various localities. A good example of the effect of step faulting is shown in the western end of the exposure of sedimentary rocks in the Ship Mountains and also in the southern end of Bristol Mountain. The Invasion of Marine Waters—The invasion of marine waters in early Cambrian time is well known in the Cordilleran geosyncline. It began early in the period, entering the continent at about the lati- tude of the present Gulf of California, passing inward across southern California and across Nevada toward the north for several hundred miles. This sea probably connected with the Arctic Ocean. This por- tion of the continent transgressed by the early Cambrian sea was far advanced in the geomorphic cycle, the country being a peneplain. The surface of the basal complex, which is granite in the area studied, is fresh and is entirely devoid of any regolith. The sea probably advanced slowly over southern California and the wave action removed the regolith, depositing the quartz as sandstone near. the strand line on the smooth wave cut surface of the fresh granite complex; while the remaining granite materials were pulverized to fine sediments, carried farther out to sea and deposited as mud overlying the sands. Pre-Cambrian Granite-——The pre-Cambrian granite is the oldest rock in the region and underlies the sedimentary formations. It out- crops along the western border of Bristol Mountain where overlain by Paleozoic strata, but at other places where not covered by Tertiary lavas it forms a considerable part of the range. According to Cavins,* the principal minerals of the granite are erystals of orthoclase which are an inch or more in length, quartz, and brown biotite. The quartz and feldspar constitute about 90 per cent of the rock, being present in the proportion of about one to two. Lower Cambrian.—The lower Cambrian is composed of a thick bed of quartzite at the base, resting on a worn surface of the pre-Cambrian 4 Bachelor’s thesis, University of California, 1915. 4 University of California Publications in Geology [Vow. 18 granite. Although no fossils were found in this quartzite it is probably Cambrian in age. About 10 feet above the base of the quartzite there is a 10-foot bed of conglomerate, composed of quartz pebbles in a quartzite matrix. The lowest 2 or 3 feet of quartzite are usually cross-bedded and often contain feldspar fragments, but the greater part of the stratum is made up of well sorted and rounded quartz grains firmly cemented together. An arenaceous shale having an average thickness of 22 feet rests conformably on the surface of the quartzite. It contains numerous beds of quartzite from 1 to 3 inches thick and is highly fossiliferous. A bed of very hard, dark blue to black, nodular limestone or marble lies conformably above the shale and is quarried for marble in several places. Although no fossils were found in this limestone it is considered to be the upper limit of the Lower Cambrian. Middle Cambrian.—The Middle Cambrian, as determined by a few fossils, consists of a massive arenaceous shale resting conformably on the nodular blue limestone. The shale is light gray to brown or black, and contains numerous beds of quartzite and calcareous sandstone. Although a careful search was made for fossils in this shale the writer was unable to find any; but Mr. Cavins, at the request of the writer, revisited the region and found a few specimens of the trilobite Bathyuriscus about 12 feet from the top of the shale bed. Carboniferous ——The Carboniferous is represented by a thick bed of massive limestone or marble which rests apparently conformably on the Middle Cambrian shale. A few fragments of fossils consisting of very poorly preserved, rounded, crinoid stems and faint impressions of coral were found on the upper surface of the hmestone. Mr. Darton® reports numerous fossils which he found in the upper part of this limestone that definitely place it in the Carboniferous. Owing to the massive character of the entire bed of limestone, notwithstanding the lack of fossils in the lower portion, it is all included in the Carboniferous. 5 Personal communication. 1921] Clark: Lower and Middle Cambrian Formations BRISTOL MOUNTAIN SECTION The Bristol Mountain section represents the section of Paleozoic sedimentary rocks present in Bristol Mountain northeast of Cadiz, California. The sediments range in age from Lower Cambrian to ‘ Carboniferous and are present in two localities in the range; one near the southern end, or about two and one-half miles northeast, and the other about five miles due north of Cadiz, San Bernardino County, California. Estimated P thicknes Carboniferous: am oe White to gray or brown limestone which in many places is partially crystalline while in others, where metamorphism has been more Inen'sem Usealbered GO mMan ble sees ee enene tence sen eaecceems sre ceeeecacteceeacacesansnsasaee Middle Cambrian: Light gray to brown or black arenaceous shale containing numerous thin beds of sandstone and quartzite .........-.--.---------------ee ee Lower Cambrian: Dark brown to blue, or black nodular limestone or marble, which is very hard and is largely made up of nodules that weather out and lie SLO MME STNG Oy AERH WOE) DUB ERY CY Fine arenaceous shale containing numerous thin beds of sandstone and quartzite, replete with Lower Cambrian fossils -....................-.. Quartzite composed of well sorted quartz grains firmly cemented LOY SSSI EC ee PRE EP er aeRO e PPE PPE EEE Conglomerate composed of rounded quartz pebbles imbedded in a QUArtZite! Mabe 222i ose cesdcct cece cee ccnecssstsaccessceucccecsnddsestst cdsecoescsessuecheve Deedaces Quartzite composed of well rounded quartz grains, cross-bedded near the base, where it contains numerous fragments of feldspar; lies unconformably on an erosional surface of the pre-Cambrian Fhe YA 5) ee ee a ere ee eee TotalimSe Ctl nis el CC ban cteeeee reese eere eee ere sage ee ee lta eon SS 120 bo OU 6 University of California Publications in Geology [Vou.18 FAUNAS The fauna obtained from Bristol Mountain consists of several species of trilobites and one species of brachiopod. All of the trilobites with the exception of the Middle Cambrian form, Bathyuriscus, were found in a thin bed of arenaceous shale in the Lower Cambrian and all the species were so intimately associated that fragments of thoracic segments could not. definitely be differentiated. A similar confusion was encountered in attempting to distinguish between fragments of the hypostoma, consequently several of the species are based on the cephalon only. Lower Cambrian.—The fauna of the Lower Cambrian consists of four species of trilobite and one brachiopod. These forms represent the upper part of the Lower Cambrian or the Olenellus zone. FAUNA OF THE LOWER CAMBRIAN Mesonacis gilberti, Meek. Olenellus fremonti, Walcott. Callavia = C.? nevadensis, Walcott. Wanneria? cadizensis, n. sp. Micromitra (Paternia) prospectensis, Walcott. Middle Cambrian.—Only one species that could be definitely determined was found in the Middle Cambrian. Two or three speci- mens similar to Bathyuriscus howelli were found near the top of the massive shale of the Middle Cambrian. This species is probably new, but the cephalons of all the specimens were crushed so that the original characters could not be accurately determined. It is referred to B. howelli as it has eight thoracic segments and seems to correspond to this species excepting in the fifth segment, which is broader than any of the others and terminates in a long spine that curves well back toward the pygidium. It is therefore called B. howelli var. lodensis. Carboniferous—The carboniferous is represented by numerous fragments of rounded crinoid stems and faint outlines of corals together with indeterminable organic remains. According to Mr. Darton, the Carboniferous also contains Spirifer rockymontanus, Michelina, sp., Cliothyridina?, sp., ete. 1921] Clark: Lower and Middle Cambrian Formations ba | CORRELATION The Cambrian section of the Mojave Desert may possibly be correlated with the Cambrian of central and eastern Nevada. Accord- ing to Walcott," Olenellus is found in a thin bed of shale lying just above a massive quartzite in several localities in Nevada, notably in the Eureka District, in the Highland Range, and also in the Big Cot- tonwood section of Utah. This shale is near the top of the Lower Cambrian in the localities just mentioned and in the Mojave region it appears to have a similar position. The Lower Cambrian quartzite in Bristol Mountain rests on an erosional surface of pre-Cambrian granite. In many of the sections of the Great Basin containing Cambrian sediments, the bottom of the sedimentary series is not exposed, but, according to Hershey,” the Lower Cambrian just west of Clover Valley in eastern Nevada rests on pre-Cambrian granite and schists. Spurr® thinks that probably much of the Cambrian in northeastern Nevada is underlain by pre- Cambrian igneous rocks. However, he states that some granites which have been supposed to be pre-Cambrian have upon investigation been proved to be later intrusives. In the Mojave Desert region these later or post-Carboniferous granites are abundant and have been the principal cause of the metamorphism, but the pre-Cambrian granites and schists occur in large areas and are cut by the later granite. The writer is indebted to Dr. C. D. Waleott for very kindly review- ing the manuscript of this paper. 6 U.S. Geol. Surv. Bull. No. 81, 1891. 7 Am. Jour. Sci. Ser. 4, vol. 34, p. 267, 1912. 8U.8. Geol. Surv. Bull. No. 208, p. 27, 1903. UNIVERSITY OF CALIFORNIA PUBLICATIONS BULLETIN OF THE DEPARTMENT OF GEOLOGICAL SCIENCES Vol. 13, No. 2, pp. 9-17, 10 text ee Vol. 13, No. 3, pp.19-21, 1 text figure Deemed fae NOE! NOTES ON PECCARY REMAINS FROM RANCHO LA BREA BY JOHN C. MERRIAM anp CHESTER STOCK NOTE ON AN HIPPARION TOOTH FROM WHE SLESTAN DEPOSITS. OF. THE BERKELEY HILLS, CALIFORNIA BY CHESTER STOCK UNIVERSITY OF CALIFORNIA PRESS BERKELEY, CALIFORNI i WILLIAM WESLEY & SONS, LONDON 5 Agent for the series in American Archaeology and ‘Ethnology, Botany, Physiology, and Zoology. i GEOLOGY.—Anprrw C. Lawson, Editor. Price, volumes 1-7, $3.50; olan 8 al $5.00. Volumes 1-11 completed; volumes 12 and 13 in progress. A list volumes 1 to 7 will be sent upon request. VOLUME 8 ee 1. Is the Boulder ‘‘Batholith’’ a Laccolith? «A Problem in Ore-Genesis, by Andre gh Oe La WSOM cu -2an2c-nceoteannseacectncanedattnabten cb recs Seet eSB cote 2. Note on the Faunal Zones of the Tejon Group, by Roy E. Dickerson ... 3. Teeth of a Cestraciont Shark from the Upper Triassic of Northern California, Harold: ©. Bryant: 5..0--0.2 2 ee A 4, Bird Remains from the Pleistocene of San Pedro, California, by Loye Holmes M: 5. Tertiary Echinoids of the Carrizo Creek Region in the Colorado Desert, by Will OW ROW ine pnccenccen conten etbttee dec ies sete naa cee cap age oa EO 6. Fauna of the Martinez Eocene of California, by Roy Ernest Dickerson ...........-. 7. Descriptions of New Species of Fossil Mollusca from the Later Marine Neocene Co ie California, by Bruce. Martin’ .72......2cee ce ‘ae ae ears 8. The Fernando Group near Newhall, California, by Walter A. English -.....c2-2-c-cecc---- 9. ee Deposition in and near ee ee Rocks by Meteoric Waters, by a7 C. awson : 11. The Martinez and Tejon Eocene and Associated Formations of the oe Mountains, by Roy EH. Dickerson 12. The Occurrence of Tertiary Mammalian Remains in Northeastern Nevada, by sone Ce Merriam te. occiaecec coe 2 ea eece onkuet abl eecnacte cong cade sed eanucs otro aan age A Se ae 13. Remains of Land Mammals from Marine Tertiary Beds in the Tejon Hills, Cali. fornia, by John C. Merriam: -.......-.:..22--.--2etece creed ceneecceseessesntneeteant 14. The Martinez Eocene and Associated Formations at Rock Creek on the Western — Border of the Mohave Desert Area, by Roy HE. Dickerson 15. New Molluscan Species from the Martinez Eocene of Southern California, by Roy Bi, Dickerson 0-2 2.--2- ss... ceece dee deceednen ede onennwen tn enade rapes eesti aE a rr 16. A Proboscidean Tooth from the Truckee Beds of Western Nevada, by joe 1ee IB UW ALOR, | ascetics -baancnecennctcbeenegeec endian ice catben Sane cones oo tet eee Mea Net SONNE ERT oe a ee a fas epee 17. Notes on the Copper Ores at Ely, Nevada, by Alfred R. Whitman = 18. Skull and Dentition of the Mylodont Sloths of Rancho La Brea, by Chester Stock. _19. Tertiary Mammal Beds of Stewart and Ione Valleys in West-Central Nevada, es John P. Buwalda 20, vertiary Echinoids from the San Pablo Group of Middle California, by William \ WY. ROW. esc n ce no ea ie eacee w cree e e Pass, near Pyramid Lake, Nevada, by John C. Merriam -....-022..2.c2ec2seceecnseeeneeea ass 22. The Fauna of the San Pablo Group of Middle California, by Bruce L. Clark ............ , VOLUME 9 ae ih New! Species of the Hipparion Group from the Pacific Coast and Great Basin Prov- inces of North America, by John C. Merriam 02.2. .o.i-cen ec coeceenepeceeccpnecncnecne=> tensor 2. The C-ecurrence of Oligocene in the Contra Costa Hills of Middle California, wh Brn opal, lark os 28g ta 3. The E}\ ‘ene Profiles of the Desert, by Andrew C. Lawson ... 4. New He s from the Miocene and Pliocene of California, by John C. Merriam 5. Corals f\ --e Cretaceous and Tertiary of California and Oregon, by Jorgen Nomina j= “SUitRets.2i "Ue seeueee tee | snaaus taeees foeaaers < eer yan Son ee 6. Relations vertebrate to the Vertebrate Faunal Zones of the Jacalitos and _ Etcheg ms in the North Coalinga Region, California, by Jor WNomlay _Sihe fos 6 bs ee a eee : 7. A Review \ ” 50 californicus, by Loye Holmes Miller :...... 8. The Owl Ru ‘o La Brea, by Loye Holmes Miller ............. 9. Two Vulturi(, 2 Pleistocene of Rancho La Brea, by Loye Miller _.....! \ Bits UNIVERSITY OF CALIFORNIA PUBLICATIONS BULLETIN OF THE DEPARTMENT OF GEOLOGICAL SCIENCES Vol. 13, No. 2, pp. 9-17, 10 text figures December 22, 1921 NOTES ON PECCARY REMAINS FROM RANCHO LA BREA BY JOHN C. MERRIAM ann CHESTER STOCK CONTENTS PAGE TET NE EAU OHO a a ee ee a Pe Pe rr eee set 9 aby Sonus; POSSibliy Me Sp. OL We SWDSP soso co. o asec eco cee cece neccceen ae eenecereeseeeceeceeeseees 10 Scull eevee sce eg ee cs Ee ee ee Sans Sete a eereeeeeteee 10 UD eee rhs oa) 72 ee A ae a ae Ee RE ei Pe OE 13 ITN LE TNC TIES ee eee cate rae Meee bs a Oe ten eee eee Sa cs cescegsbegisece ey COTTON LTRS IC ee Sa a ee om ata fe RO, RP ee a Ly INTRODUCTION Study of the collections of Pleistocene mammals obtained by the University of California from the asphalt deposits of Rancho La Brea has revealed a single astragalus belonging to a peccary. Later execa- vations at Rancho La Brea conducted by the Los Angeles Museum of History, Science and Art under the direction of the late Dr. Frank S. Daggett have brought to hght additional remains of the dicotyline group of mammals, among which are a fairly preserved skull and some incomplete limb elements. These are now in the palaeontological col- lections of the Los Angeles Museum and afford a better opportunity than does the single astragalus to secure needed information concern- ing the group in the Pleistocene of California. Infrequeney of occurrence of pecearies in the asphalt beds lends special interest to the record of their presence, and may be of greater or less significance in an interpretation of problems relating to the Rancho La Brea fauna. The completeness of the record of Pleistocene mammalian life in western North America as offered by the collections from Rancho La Brea makes it desirable to ascertain the status of the more uncommon types occurring in the asphalt beds, particularly of forms closely related to species met with in other Pleistocene deposits. 10 University of California Publications in Geology [ Von. 13 PLATYGONUS, possibly n. sp. or n. subsp. SKULL The skull, no. 4400, L. A. M. H. 8. A.,1 from Rancho La Brea pos- sesses the facial region including the palate and superior dentition. The posterior portion of the specimen has suffered much _ loss, but on the left side there remain structures around the orbit and posterior to the glenoid fossa that furnish some information of this region of the cranium. At the anterior end of the snout the nasals are broken away. The teeth, with exception of M+ and M2, show a moderate degree of wear. M2? and particularly M+ are well worn, as is also the anterior edge of the superior canine. Specimen 4400 is definitely referable to the genus Platygonus. The diastema between superior canine and P? is not characterized by great length as in Mylohyus, but is shghtly longer than in Tayassu. It reaches a length slightly greater than that of the premolar series. Two incisors are present in each premaxillary, their alveoli indicating that the forward or medial incisor was very large while the posterior or lateral tooth, situated immediately behind the former, was much smaller. P4 is not molariform. Although the cheek-tooth series has been subjected to attrition, the cusps of the individual teeth seem to be characterized by a more prominent development than in teeth of Tayassu. The specimen available from Rancho La Brea agrees fairly closely in size with peceary skulls from the Pleistocene of Kansas described by Williston? under the species Platygonus leptorhinus. It likewise compares favorably in this character with skull specimens referred to P. compressus. In no. 4400 a shallow fossa is present above and be- hind the posterior margin of the exit of the infra-orbital canal, while a deeper fossa is located in front of the opening. Fossae comparable to these are noted by Williston in a female skull of P. leptorhinus, but are lacking, according to Wagner,® in the skull of P. compressus from the Pleistocene of Michigan. While the groove or suleus that extends along the lateral side of the snout is present in the California skull, a continuation of the groove can not be traced to the top of the skull because of the destruction of the greater portion of the dorsal 1 Los Angeles Museum of History, Science and Art, Los Angeles, Calif. 2 Williston, S. W., Restoration of Platygonus. Kansas Univ. Quar., vol. 3, pp. 23-39, pls. 7 and 8, 1894. ‘Wagner, G., Observations on Platygonus compressus Le Conte. Jour. Geol., vol. 11, pp. 777-782, figs. 1-4, 1903. 1921] Merriam—Stock: Notes on Peccary Remains 11 Figs. 1, 2, and 38. Platygonus, possibly n. sp. or n. subsp. Skull, no. 4400, L. A. Mus. Hist. Sci. and Art Coll. X¥,. Fig. 1, lateral view; fig. 2, ventral view; fig. 38, dorsal view. Rancho La Brea beds. 12 University of California Publications in Geology [ VoL. 13 surface. A scar on the preserved part of the frontal suggests the end of the groove of the left side. If this does represent the dorsal termi- nation, the latter is situated somewhat closer to the rim of the orbit than in P. leptorhinus or in P. compressus. Judging from the small portion of the parietal that remains, the dorsal margin of the temporal fossa was apparently not prominent in the specimen from Rancho La Brea. The depth of the malar below the orbit in the skull from the asphalt deposits is exceeded by the corresponding measurement in a single skull of the Kansas series. It is deeper than in the specimens from Rochester, New York, determined by Leidy* as belonging to P. compressus. The malar is only shghtly deeper in no. 4400 than in the Michigan specimen of P. compressus. The Rancho La Brea species, in shortened diastema, approxi- mates more closely the modern pecearies than do other forms of Pla- tygonus from the Pleistocene of North America. In no. 4400, however, the diastema between the canine and the cheek teeth is distinetly longer than in Tayassu, and the length of the diastema approximates closely that of the upper premolar series. The diastema in the specimen from Rancho La Brea is much shorter than in the skull from Kentucky re- ferred by Leidy® to P. compressus and in the Pleistocene peceary skulls from Rochester, New York. It is also shorter than in specimens referred to P. leptorhinus by Williston, and is distinctly shorter than in the skull of P. compressus described by Wagner. In skulls de- scribed by Leidy and by Williston the canine tuberosity seems always to extend farther dorsally along the side of the snout than in Platyg- onus from Rancho La Brea. The height of the canine tuberosity is not so great in no. 4400 as in the specimen from Michigan, while in both skulls the height equals the length of the post-canine hiatus. Between the alveoli for the medial incisors a canal extends forward from the anterior palatine foramen. The palate in the specimen from the asphalt beds is not so broad as that of P. alemant from the Pleisto- cene of Mexico. The median portion of the palate behind M? reaches upward to the postnarial notch, the angle which this slope makes with the plane of the palate being greater than in Tayassu. The anterior tuberosities of the basioccipital are separated in median line by a wider groove than in P. leptorhinus, and the lateral arm of the basi- sphenoid, which joins with the alisphenoid, lies more in advance of the contact between basioccipital and basisphenoid than in the Kansas ‘Leidy, J.. On Platygonus, an extinct genus allied to the peccaries. Trans. Wagner Free Inst. Sci., vol. 2, pp. 41-50, pl. 8, fig. 1, 1889. 5 Leidy, J., Trans. Amer. Philos. Soc., vol. 10, pp. 830-341, pls. 386 and 37, 1853. 1921] Merriam—Stock: Notes on Peccary Remains 13 form. The comparisons of basioccipital and basisphenoid have been made, however, with only a single specimen of P. leptorhinus in the collections of the University of California. DENTITION The shape of the superior premolar teeth, subject to some variation in P. compressus, does not seem to offer a suitable character for diag- nostic purposes. In the more fundamental characters relating to structures of the tooth crown, the teeth in the Rancho La Brea skull resemble closely those of P. leptorhinus and of P. compressus. The superior premolar-molar series in no. 4400 from Rancho La Brea is longer than in specimens of P. compressus and P. leptorhinus, although this difference is slight. The cheek teeth approximate very Fig. 4. Platygonus, possibly n. sp. or n. subsp. Superior cheek-tooth series, no. 4400, L. A. Mus. Hist. Sci. and Art Coll. X 1. Lateral and occlusal views. Rancho La Brea beds. closely in length the upper series of P. alemani from Mexico. The first and second molars in the California specimen are slightly larger than in the Kansas skulls, while measurements of M2 may be exceeded by those in the latter. P#4 is shghtly larger than the corresponding tooth in the Kansas specimen. All the teeth in the California skull are smaller than those of Platygonus vetus when comparison is made with the measurements given by Williston. With the exception of the an- teroposterior diameter of M4, the teeth are shghtly larger than in P. compressus from Kentucky.® 6 Leidy, J., op cit., 1853. 14 Unversity of California Publications in Geology [ Vou. 13 P2 is subtriangular in horizontal section with the anterior side subacute, thus differing slightly from Leidy’s specimens from Ken- tucky. Two cusps are developed on the crown, the inner one of which is somewhat the larger. Mesotaria ambigua. Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 41, no. 4, pp. 796-797. Brussels, 1876.—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 56-60, pl. 9. Brussels, 1877.—Mourlon, M., Bull. Acad. Roy. des Sci., des Léttres et des Beaux-Arts de Belgique (2), vol. 43, no. 5, p. 607. Brussels, 1877. (Berchem; Wommelghem; Deurne?; Borgerhout?.)—Allen, J. A., Misc. Publ. no. 12, U. 8S. Geol. and Geog. Surv. Terr., Dept. Interior, pp. 219, 478. Washington, D. C., 1880.—Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896.—Palmer, T. S., North Am. Fauna no. 23, p. 416. Washington, D. C., 1904.—True, F., Prof. Paper no. 59, U. 5. Geol. 110 University of California Publications in Geology [Vou. 18 Surv., p. 147. Washington, D. C., 1909.—Toula, F., Beitriige z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, pp. 52, 55. Wien und Leipzig, 1898. TYPE LOCALITY.—Second and third sections, also at Wommelghem, Antwerp Basin, Belgium. Middle Pliocene. MESOTARIA? sp. Cystophora proboscidea. Lyell, C., London and Edinburgh Philos. Mag., vol. 33, p. 188, 1843.—_lLyell, C., Neues Jahrbuch f. Mineralogie, pp. 221-222. Stuttgart, 1844.—Lyell, C., Am. Jour. Sci., vol. 46, p. 319. 1844.—Lyell, C., Proce. Geol. Soc. London, vol. 4, no. 92, p, 32. 1846. —Allen, J. A., Misc. Publ. no. 12, U. S. Geol. and Geog. Surv. Terr., Dept. Interior, p. 470. Washington, D. C., 1880. ; Ph. (Cystophorad) proboscidea. Giebel, C. G., Fauna der Vorwelt, vol. 1, p. 224, Leipzig, 1847. : Ph(oca) proboscidea. Pictet, F. J., Traité de Paléontologie (2), vol. 1, p. 253. Paris, 1853—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, p. 33. Brussels, 1877. Cystophora cristata. Hay, O. P., U. S. Geol. Surv., Bull. no. 179, p. 785. Washington, 1902. TYPE LOCALITY.—In the yellowish and dark brown clay near the uppermost part of the section at Gay Head and in the green sand immediately resting upon it, Martha’s Vineyard, Massachusetts. Upper Miocene. Genus PRISTIPHOCA Gervais Pristiphoca, Gervais, P., Mem. Acad. Sci. Montpellier, vol. 2, pt. 2, pp. 308-309, pl. 6, fig. 4. 1852-53. Type, Phoca occitana Gervais and Serres. PRISTIPHOCA OCCITANA (Gervais and Serres) Phoca occitana. Gervais, P., and Serres, M. de, Ann. Sei. Nat., Paris (3), vol. 8, p. 225. 1847.—Gervais, P., Zoologie et Paléontologie frangaises (1), vol. 1, p. 140. (Part.) Paris, 1848-52.—Gervais, P., Ann. Sci. Nat., Paris (3), vol. 16, p. 152. 1851.—Gervais, P., Mem. Acad. Sei. Montpelier, vol. 2, pt. 2, pp. 308-309, pl. 6, fig. 4. 1852-53.—Gervais, P., Ann. Sci. Nat., Paris (3), vol. 20, pp. 281-282, pl.. 13, figs. 8, 8a: 1853.—Gervais, P., Bull. Soe. Geol. de France (2), vol. 10, p. 311. Paris, 1853. (Part.)—Palmer, T. 8., North Am. Fauna, no. 23, p. 563. Washington, D. C., 1904. Phoca occitanica. Pictet, F. J., Traité de Paléontologie (2), vol. 1, p. 233. Paris, 1853. Zt / Phistiphoca occitana. Gervais, P., Zoologie et Paléontologie francaises f ¢ (2), pp. 272, 273, pl. 82, figs. 4, 4a.- Paris, 1859. (Part.)—Gervais, P., Journal de Zoologie, vol. 1, p. 66. Paris, 1872. (Part.)—Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 32, no. 7, p- 5. Brussels, 1871.—Lawley, R., Atti della Soc. Toscana Sci. Nat. resid. in Pisa, vol. 1, fase. 1, p. 66. 1874. (Orciano.)—Lawley, R., Nuovi studi sopra ai pesci ed altri vertebrati fossili delle colline 1922] Kellogg: Pinnipeds from Miocene and Pleistocene Deposits 111 Toseane, pp. 103-104. Florence, 1876. (Oreiano.)—Van Beneden, P. J.. Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 25, 27, 64. Brussels, 1877. (Part.)—De Alessandri, G., Mem. Museo civico di Storia Naturale di Milano e Soc. Ital. di Sci. Nat., vol. 6, fase. 1, Dp. LiL pls ye a S97, Pristophoca occitana.—Yorsyth-Major, C. I., Atti della Soc. Toscana Sci. Nat. resid. in Pisa, vol. 1, fase. 3, p. 226. 1876. Pristiophoca occitana. Allen, J. A., Mise. Publ. no. 12, U. 8S. Geol. and Geog. Surv. Terr., Dept. Interior, pp. 477, 478, 479. Washington, D. C., 1880. Pristiphoca occitanica. Zittel, IK. v., Traité de Paléontologie, pt. 1, Paléo- zoologie, vol. 4, p. 689 (translation Barrois). Paris, 1894.—Toula, F., Beitrige z. Paliont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, pp. 49, 54. Wien und Leipzig, 1898.—Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 379. Berlin, 18 OMe : . Monachus albiventer. Ugolini, R., Palaeontographia Italica, Mem. Paleo., vol, 8, pp. 1-20, pls. 1-3. Pisa, 1902. TYPE LOCALITY.—Pliocene marine sands of Montpelier, Department of Ter- ault, France. Upper Pliocene. PRISTIPHOCA sp.? Phocidae. Stromer, H., Abhandl. Senckenb. naturf. Gesellsch., vol. 29, p. 121, pl. 20, fig. 10, Frankfurt, 1905.—Andrews, C. W., Dese. cat. Tert. vert. Fayim, Egypt, p. xi. London, 1906. TYPE LOCALITY.—Wadi Natrin, Egypt. Upper Pliocene. Genus PALHOPHOCA Van Beneden Paleophoca. Van Beneden, Bull. Acad. Roy. Sci. de Belgique (2), vol. 8, no. 11, p. 142. Brussels, 1859. Type, Paleophoca nystii Van Beneden. PALEOPHOCA NYSTII Van Beneden Phoque. Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique, vol. 20, pp. 255-258, text fig. 1. Brussels, 1853. Paleophoca nystii. Van Beneden, P. J., Bull. Acad. Roy. Sei. de Belgique (2), vol. 8, pt. 8, no. 11, pp. 123-146. Brussels, 1859—Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 41, no. 4, p. 797. Brussels, 1876.—Palmer, T. 8., North Am. Fauna, no. 23, p. 506. Wash- ington, D. C., 1904. Palaeophoca nystii. Van Beneden, P. J., Bull. Acad. Roy. Sci. de Bel- gique (2), vol. 8, pt. 8, no. 11, p. 145. Brussels, 1859.—Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 32, no. 7, pp. 10-12, pl. 2. Brussels, 1871.—Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 32, nos. 9-10, p. 171. Brussels, 1871.—Van Beneden, P. J., Ann. Mus. Roy- Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 27, 60, 65, pl. 10. Brussels, 1877——Mourlon, M., Bull. Acad. Roy. des Sci., des Léttres et des Beaux-Arts de Belgique (2), vol. 43, no. 5, p. 607. tt? University of California Publications in Geology [Vou. 13 Brussels, 1877. (Wommelghem; Deurne et Borgerhout?.)—Toula, F., Beitrage z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, p- 54. 1898. Palaeophoca nysti. Allen, J. A., Mise. Publ. no. 12, U. 8. Geol. and Geog. Surv. Terr., Dept. Interior, pp. 477, 478, 479. Washington, D. C., 1880. (Pristiphoca) nystii. Trouessart, E. L., Catalogus mammalium tam viven- tium quam fossilium, vol. 1, p. 380. Berlin, 1899. Paldophoca nystii. Roger, O., Berich naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, pp. 73-74. Augsburg, 1896. Palaophoca nystii. Toula, F., Beitrige z. Paliont. u. Geol. Osterreich- Ungarns u. d. Orients, vol. 11, p. 52. Wien und Leipzig, 1898. Phoca nystii. Gervais, P., Journal de Zoologie, vol. 1, p. 65. Paris, 1872. Phoca d’Anvers. Gervais, P., Zoologie et Paléontologie frangaises (2), pp. 274-275; Atlas, pl. 82, figs. 1, la. Paris, 1859. TYPE LOCALITY.—Upper Crag of St. Nicholas, near Antwerp, Belgium. Mid- dle Pliocene. PHOCID? Phoca ambigua. Staring, W. C. H., De Bodem van Nederland, vol. 2, pp. 282, 283. Haarlem, 1860.—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, p. 25. Brussels, 1877. (Preoceu- pied by Phoca ambigua Minster.) “*Phoque.’’ Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 32, no. 7, p. 7. Brussels, 1871. (Koerboom, near Swilbroek, Hol- land.) Palaeophoca nystii. Van Beneden, P. J.. Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 25, 61. Brussels, 1877. TypE LocaLiry.—In the bed of the Meuse River at Elsloo, near Maestricht, Holland. Middle Oligocene. Genus MONOTHERIUM Van Beneden Monotherium. Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 41, no. 4, pp. 800-801. Brussels, 1876. Type, Monotherium delognii Van Beneden. MONOTHERIUM DELOGNII Van Beneden Monotherium delognii. Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 41, no. 4, p. 800. Brussels, 1876.—Palmer, T. S., North Am. Fauna, no. 23, p. 431. Washington, D. C., 1904. Monatherium delogniit. Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 75-76, pl. 16, figs. 1-6. Brussels, 1877.— Mourlon, M., Bull. Acad. Roy. des Sci., des Léttres et des Beaux- Arts de Belgique (2), vol. 43, no. 5, p. 608. Brussels, 1877. (Borger- hout et Deurne.)—Allen, J. A., Mise. Publ. no. 12, U. S. Geol. and Geogr. Surv. Terr., Dept. Interior, p. 479. Washington, D. C., 1880.— Lydekker, R., Cat. Foss. Mamm. Brit. Mus., pt. 1, pp. 206-207. Lon- don, 1885.—Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896.—Toula, F., Beitrage 1922] Kellogg: Pinnipeds from Miocene and Pleistocene Deposits 1138 z. Paliont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, pp. 49, 52, 54. Wien und Leipzig, 1898.—Trouessart, HE. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 380. Berlin, 1897. Monotherium affine. Van Beneden, P. J., Bull. Acad. Roy. Sci. de Bel- gique (2), vol. 41, no. 4, pp. 800, 801. Brussels, 1876. Monatheriwm affine. Van Beneden, P. J.,. Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 76-77. Brussels, 1877.—Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896.—Trouessart, E. L., Catalogus mammalium tam viven- tium quam fossilium, vol. 1, p. 380. Berlin, 1897. Monatherium affinis. Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, Atlas, vol. 1, pt. 1, pl. 16, figs. 7-14. Brussels, 1877.—Mourlon, M., Bull. Acad. Roy. des Sci., des Léttres et des Beaux-Arts de Belgique (2), vol. 43, no. 5, p. 608. Brussels, 1877. (Borgerhout et Deurne.)— Allen, J. A., Mise. Publ. no. 12, U. S. Geol. and Geog. Surv. Terr., Dept. Interior, p. 479. Washington, D. C., 1880.—Toula, F., Beitrage z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, pp. 52, 54. Wien und Leipzig, 1898. TypE LocaLiry.—At Borgerhout and throughout second and third sections, Antwerp Basin, Belgium. Upper Miocene. MONOTHERIUM ABERRATUM Van Beneden Monotherium aberratum. Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 41, no. 4, p. 801. Brussels, 1876. Monatherium aberratum. Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 77-78, pl. 17.. Brussels, 1877.—Mourlon, M., Bull. Acad. Roy. des Sei., des Léttres et des Beaux-Arts de Bel- gique (2), vol. 43, no. 5, p. 608. Brussels, 1877. (Contrescarpe du fossé de l’enciente 4 Berchem.)—Allen, J. A., Mise. Publ. no. 12, U.S. Geol. and Geog. Surv., Dept. Interior, p. 479. Washington, D. C., 1880.—Toula, F., Beitrige z. Paliiont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, pp. 58, 54. Wien und Leipzig, 1898.—Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 380. Berlin, 1897. TYPE LocALITy.—In second and third sections, at Borgerhout and Turnhout, ete., Antwerp Basin, Belgium. Upper Miocene. MONOTHERIUM GAUDINI (Guiscardi) Ph(oca) gaudini. Guiseardi, G., Rendiconto dell’Acead. d. Sei. Fisiche e Matem., fase. 12, p. 207. Naples, 1870. Phoca gaudini. Guiseardi, G., Societa Reale di Napoli, Atti dell’Accad. delle Sci. Fisiche e Matem., vol. 5, no. 6, pp. 1-9, pls. 1-2. Naples, 1873.—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, p. 26. Brussels, 1877.—Allen, J. A., Mise. Publ. no. 12, U. 8. Geol. and Geog. Surv. Terr., Dept. Interior, pp. 478-479. Wash- ington, D. C., 1880.—Simonelli, V., Boll. R. Comitato Geologico d’Italia (2), vol. 10, nos. 7 and 8, p. 209, footnote. Rome, 1889.—Toula, F., Beitraige z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, pp. 51, 54. Wien und Leipzig, 1898. 114 University of California Publications in Geology — [Vou. 18 “* Phoque.’? 1872. Palaecophoca gaudini. Flores, E., Atti della Accademia Pontaniana, vol. 85, no. 18, pp. 39-40. Naples, 1895. (Pristiphoca) gaudini. Trouessart, HE. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 380. Berlin, 1899. TYPE LocALITy.—In the bituminous lime deposits of an open cave in the neighborhood of Mount Letto, about two miles to the east of Roceamorice and rear Majella, in the Compartment of Chietino, Italy. Upper Miocene. Gervais, P., Journal de Zoologie, vol. 1, pp. 64-65. Paris, MONOTHERIUM MAEOTICUM (Nordmann) Phoca pontica. Hichwald, E., Lethaea Rossica, ou Paléontologie de la Russie, vol. 3, pp. 391-400, pl. 13. Stuttgart, 1853. - (Part.) Ph(oca) maeotica. Nordmann, A. y., Palaeontologie Sudrusslands, pt. 4, p. 313, pl. 22, figs. 1-3, 6-11; pl. 23, figs. 1-3, 6-10; pl.-24, figs. 1-16. Helsingfors, 1860. Phoca macotica. Van Beneden, Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, p. 26. Brussels, 1877.—Allen, J. A., Mise. Publ. no. 12, U.S. Geol. and Geog. Surv. Terr., Dept. Interior, pp. 478, 479.—Toula, F., Beitriige z. Paliiont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, p. 50. Wien und Leipzig, 1898—True, F. W., Proce. U. S. Nat. Mus., vol. 30, no. 1475, pp. 838-839. Washington, D. C., 1906. Phoca moetica. Zittel, K. v., Traité de Paléontologie, pt. 1, Paleozoologie, vol. 4, p. 689 (translation Barrios). Paris, 1894. Phloca) mdotica. Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896.—Toula, F., Beitrige z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, p. 54. Wien und Leipzig, 1898. (Monatherium) maeoticum. Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 380. Berlin, 1899. TYPE LocALITy.—Limestone quarries in vicinity of Kischinef, province of Bessarabia, Russia. Upper Miocene. MONOTHERIUM RUGOSIDENS (Adams) Phoca rugosidens. Adams, A. L., Quar. Jour. Geol. Soc., vol. 35, pt. 3, p. 524, pl. 25, figs. 1-2. London, 1879.—Allen, J. A., Mise. Publ. no. 12, U. S. Geol. and Geog. Surv. Terr., Dept. Interior, p. 773. Washington, D. C., 1880.—Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896.— Toula, F., Beitrige z. Palaiont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, pp. 53, 54. Wien und Leipzig, 1898. (Monatherium) rugosidens. Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 380. Berlin, 1899. TYPE LOCALITY.—From the calcareous sandstone of Gozo, Maltese Islands. Upper Miocene. Genus HYDRURGA Gistel Hydrurga. Gistel, J.. Naturgeschichte des Thierreichs fir hohere Schulen, p. xi. Stuttgart, 1848. Type, Phoca leptonyx Blainville. 1922] Kellogg: Pinnipeds from Miocene and Pleistocene Deposits 115 HYDRURGA LEPTONYX (Blainville) Stenorynchus leptonyx Haast, J.. Nature, vol. 14, p. 577. 1876—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, p. 35. Brussels, 1877. Typr Locatiry.—Moa Bone Point Cave, Middle Island, Bank’s Peninsula, New Zealand. Recent. Genus LOBODON Gray Lobodon. Gray, J. E., Zool. Voy. H. M. 8. ‘‘ Erebus and Terror,’’ pt. 1, Mamm., p. 2. 1844, “ Type, Phoca careinophaga Hombron and Jaequinot. LOBODON VETUS (Leidy) Stenorhynchus vetus. Leidy, J., Proc. Acad. Nat. Sci. Phila., vol. 6, p. 377. 1853.—Gray, J. E., Cat. whales and seals Brit. Mus., p. 10. London, 1866.—Allen, J. A., Misc. Publ. no. 12, U. S. Geol. and Geog. Surv. Terr., Dept. Interior, pp. 475-476. Washington, D. C., 1880.—Toula, F., Beitrage z. Paldont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, p. 50. Wien und Leipzig, 1898. Lobodon vetus. Leidy, J., Jour. Acad. Nat. Sei. Phila. (2), vol. 7, pp. 415-416. 1869.—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, p. 28. Brussels, 1877.—Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 381. Berlin, 1897. TYPE LOCALITY.—Green-sand marl near Burlington, Burlington County, New Jersey. Upper Cretaceous. Genus GRYPHOCA Van Beneden Gryphoca. Van Beneden, P. J., Bull. Acad. Roy. Sei. de Belgique (2), vol. 41, pp. 798-799. Brussels, 1876. : Type, Gryphoca similis Van Beneden. GRYPHOCA SIMILIS Van Beneden Gryphoca similis. Wan Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 41, no. 4, pp. 798-799. Brussels, 1876—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 69-70, pl. 13, figs. 1-21. Brussels, 1877——Mourlon, M., Bull. Acad. Roy. des Sci., des Léttres et des Beaux-Arts de Belgique (2), vol..43, no. 5, p. 607. Brussels, 1877. (Wommelghem; Deurne et Borgerhout.)—Allen, J. A., Mise. Publ. no. 12, U. 8. Geol. and Geog. Surv. Terr., Dept. Interior, p- 479. Washington, D. C., 1880.—Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 75. Augsburg, 1896.—Toula, F., Beitraige z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, pp. 52, 55. Wien und Leipzig, 1898.—Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 382. Berlin, 1897. TyPE LocALity.—In second and third sections, at Moortsel and Wommel- ghem, etc., Antwerp basin, Belgium. Middle Pliocene. 116. S- University of California Publications in Geology — [Vou. 18 Genus PROPHOCA Van Beneden Prophoca. Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 41, no. 4, pp. 801-802. Brussels, 1876. Type, Prophoca.rousseawi Van Beneden. PROPHOCA ROUSSEAUI Van Beneden Prophoca rousseawi. Van Beneden, P. J., Bull. Acad. Roy. Sei. de Belgique (2), vol. 41, no. 4, pp. 801-802. Brussels, 1876.—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 79-80, pl. 18, figs. 1-11. Brussels, 1877.—Mourlon, M., Bull. Acad. Roy. des Sci., des Léttres et des Beaux-Arts de Belgique (2), vol. 43, no. 5, p. 608. Brussels, 1877. (Fort 3 [Borsbeeck]; fosse capital pres Deurne et Vieux-Dieu [Mortsel].)—Allen, J. A., Mise. Publ. no. 12, U. 8. Geol. and Geog. Surv. Terr., Dept. Interior, p. 479. Washington, D. C., 1880. —Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896.—Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 383. Berlin, 1897.—Palmer, T. 8., North Am. Fauna, no. 23, p. 574. Washington, D. C., 1904. Prophoca rousseani. Toula, F., Beitrage z. Palaont. u. Geol. Osterreich- Ungarns u. d. Orients, vol. 11, pp. 53, 54. Wien und Leipzig, 1898. TypE LocaLiry.—Black sands in second and third sections, at Moortsel, near Deurne, ete., Antwerp basin, Belgium. Upper Miocene. PROPHOCA PROXIMA Van Beneden Prophoca proxima. Van Beneden, P. J., Bull. Acad. Roy. Sei. de Bel- gique (2), vol. 41, no. 4, p. 802. Brussels, 1876.—Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 80-81, pl. 18, figs. 12-16. Brussels, 1877.—Mourlon, M. Bull. Acad. Roy. des Sci., des Léttres et des Beaux- Arts de Belgique (2), vol. 43, no. 5, p. 609. Brussels, 1877. (Borger- hout et Vieux-Dieu | Mortsel].)—Allen, J. A., Mise. Publ. no. 12, U.S. Geol. and Geog. Surv. Terr., Dept. Interior, p. 479. Washington, D. C., 1880.—Toula, F., Beitrige z. Paliont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, p. 53. Wien und Leipzig, 1898.—Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896.—Trouessart, EH. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 383. Berlin, 1897. TYPE LOcALITY.—Black sands in second and third sections, at Borgerhout, Moortsel, ete., Antwerp basin, Belgium. Upper Miocene. Genus ERIGNATHUS Gill Erignathus. Gill, T., Proce. Essex Inst., vol. 5, Communications, p. 5. 1866. Type, Phoca barbata Erxleben. : ERIGNATHUS BARBATUS (Erxleben) P(hoca) barbata. Blainville, H. M. D., Ostéographie ou description icono- graphique, vol. 2, p. 42. Paris, 1839-64. (Iceland?.)—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, p. 34. Brussels, 1877. 1922] Kellogg: Pinnipeds from Miocene and Pleistocene Deposits 117 Ph(oca) barbata foss. Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896.—Toula, F., Beitriige z. Palaéont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, p. 54. Wien und Leipzig, 1898. Phoca (Erignathus) barbata. Newton, HE. T., Geological Magazine, n.s., decade 3, vol. 6, no. 4, pp. 147-148, pl. 5, figs. 2, 2a. London, 1889.— Newton, E. T., Vertebrata of Pliocene deposits of Britain, Mem. Geol. Surv. United Kingdom, p. 19. London, 1891. (Hrignathus) barbatus foss. Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 383. Berlin, 1897. TYPE LOCALITY.—From the Cromer Forest bed at Overstrand, near Cromer, Norfolk County, England. ?Upper Pliocene. Genus PLATYPHOCA Van Beneden Platyphoca. Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 41, no. 4, p. 798. Brussels, 1876. Type, Platyphoca vulgaris Van Beneden. PLATYPHOCA VULGARIS Van Beneden Platyphoca vulgaris. Wan Beneden, P. J., Bull. Acad. Roy. Sei. de Bel- gique (2), vol. 41, no. 4, p. 798. Brussels, 1876——Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 67-68, pl. 12, figs. 1-11. Brussels, 1877——Mourlon, M., Bull. Acad. Roy. des Sci., des Léttres et des Beaux-Arts de Belgique (2), vol. 43, no. 5, p. 607. Brussels, 1877. (Deurne; Anvers et Borgerhout.)—Allen, J. A., Mise. Publ. no. 12, U. 8. Geol. and Geog. Surv. Terr., Dept. Interior, p. 479. Washington, D. C., 1880.—Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 52, p. 75. Augsburg, 1896.— Toula, F., Beitrage z. Paliont. Osterreich-Ungarns u. d. Orients, vol. 11, pp. 52, 55. Wien und Leipzig, 1898.—Trouessart, EH. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 384. Berlin, 1897.—Palmer, T. 8., North Am. Fauna, no. 23, p. 545, Washington, D. C., 1904. TYPE LOcALITY.—In the second and third sections, at Borgerhout, Deurne, ete., Antwerp basin, Belgium. Middle Pliocene. Genus PHOCA Linnaeus Phoca. Linnaeus, K. v., Systema Naturae, 10th ed., vol. 1, p. 37. Holmiae, 1758. Type, Phoca vitulina Linnaeus. PHOCA, near VITULINA Linnaeus “*Seal.’’ Knox, R., Mem. Wernerian Nat. Hist. Soc., vol. 5, pt. 2, p. 572. Edinburgh, 1826. (Camelon.)—Allman, G. J., Proe. Royal Soe. Edin- burgh, vol. 4, p. 99. 1858. (Tyrie; Kirkaldy.)—Allman, G. J., Proe. Royal Soc. Edinburgh, vol. 4, p. 190. 1859. (Portobello.) 11s University of California Publications in Geology [ Von. 13 Phoca vitulina. Holl, F., Handbuch der Petrefactenkunde, p. 69. Dres- den, 1829. (Part.)—Page, D., The Athenaeum, no. 1537, p. 479. Lon- don, 1857. (Cupar Muir clay pits.)—Page, D., Archiv Sci., Phys. et Nat., vol. 35, p. 69. Geneva, 1857.—Page. D., Report 28th meeting Brit. Assoc. Ady. Sci., Trans. sections, p. 104. Leeds, 1859. (St. Andrews Bay; brick clays at Garbridge and Seafield.)—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 28, 34. Brussels, 1877.—Toula, F., Beitrage z. Palaont. u. Geol. Osterreich- Ungarns u. d. Orients, vol. 11, p. 50. Wien und Leipzig, 1898. Phoca groenlandica?. Walker, R., Ann. and Mag. Nat. Hist. (3), vol. 12, no. 71, pp. 382-387. London, 1863. (Stratheden.) Phoca hispida. Turner, W., Jour. Anat. and Phys., vol. 4, pp. 260-270. London, 1870. (Grangemouth.)—Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 32, no. 7, p. 6. Brussels, 1871.—Turner, W., The marine mammals in the anatomical museum of the University of Edinburgh, pt. 3, pp. 185-186. London, 1912. Type LocaLity.—Brick clays of Camelon in the upper basin of the Forth, Linlithgow County, Scotland. Pleistocene. i PHOCA sp. Phoca vitulina. Bell, R., and Bell. A., Proc. Geol. Assoc., vol. 2, p. 212. 1872. Phoca. Woodward, H. B., The geology of Norwich, Mem. Geol. Surv. United Kingdom, p. 55. London, 1881—Newton, E. T., Vertebrata of Forest bed series of Norfolk and Suffolk, Mem. Geol. Surv. United Kingdom, p. 26. London, 1882.—Newton, E. T., Vertebrata of Plio- cene deposits of Britain, Mem. Geol. Surv. United Kingdom, pp. 18-19, pl. 2, figs. la, 1b. London, 1891. Type Locaniry.—Norwich Crag of Bramerton, England. Upper Pliocene. PHOCA VITULINOIDES Van Beneden Phoca vitulinoides. Wan Beneden, P. J., Bull. Acad. Roy. Sci. de Bel- gique (2), vol. 32, no. 7, pp. 8-9, pl. 1. Brussels, 1871.—Gervais, P., Jour. de Zool., vol. 1, p. 65. Paris, 1872.—Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 41, no. 4, p. 800. Brussels, 1876. —Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 27, 72-74, pl. 15. Brussels, 1877—Mourlon, M., Bull. Acad. Roy. des Sei., des Léttres et des Beaux-Arts de Belgique (2), vol. 43, no. 5, p. 608. Brussels, 1877. (Borgerhout; Fort 38, Borsbeeck.)— Allen, J. A., Mise. Publ. no. 12, U. S. Geol. and Geog. Surv. Terr., Dept. Interior, p. 479. Washington, D. C., 1880.—Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896.—Trouessart, E. L., Catalogus mammalium tam viven- tium quam fossilium, vol. 1, p. 385. Berlin, 1897. Phoca vitilinoides. Toula, F., Beitrige z. Paliont u. Geol. Osterreich- Ungarns u. d. Orients, vol. 11, p. 52. Wien und Leipzig, 1898. Typr Locatity.—In the third section, at Borsbeek, ete., Antwerp Basin, Belgium. Middle Pliocene. 1922] Kellogg: Pinnipeds from Miocene and Pleistocene Deposits 119 PHOCA MOORI Newton Phoca moori. Newton, E. T., Quar. Jour. Geol. Soc. London, vol. 46, pp. 446-447, pl. 18, figs. 8a, 3b. 1890—Newton, E. T., Mem. Geol. Surv. United Kingdom, p. 19, pl. 2, figs. 2a, 2b. London, 1891. (Red Crag Nodule-bed of Waldringfield.)—Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896.— Toula, F., Beitrage z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, p. 54. Wien und Leipzig, 1898.—Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 385. Berlin, 1897. TypPrE LOcALITY.—Nodule bed of the Red Crag at Foxhall, four miles south- west of Woodbridge, Suffolk County, England. Middle Pliocene. PHOCA VINDOBONENSIS Toula Phoca vindobonensis. Toula, F., Beitrige z. Paliont. u. Geol. Osterreich- Ungarns u. d. Orients, vol. 11, pp. 47-71, pls. 9, 10, 11. Wien und Leipzig, 1898. Phoca pontica. Peters, K. F., Sitzungsber. math.-naturw. Cl. d. k. Akad. Wissensch., vol. 55, pt. 2, pp. 110, 111. Wien, 1867. (Hernals.) Phoca. Steindachner, ¥., Sitzungsber. math.-naturw. Cl. K. k. Akad. Wissensch., vol. 37, no. 21, p. 674. Wien, 1859. Phoques. Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 25, 26. Brussels, 1877. TYPE LOCALITY.—Kreindl’s brickyard on the Nussdorf road near Heiligen- stadt, Province of Nieder-Osterreich, Austria. Upper Miocene. PHOCA VIENNENSIS Blainville Phoca vitulina. Holl, F., Handbuch der Petrefactenkunde, p. 69. Dres- den, 1829. (Holitsch.)—Andrian, F. F. v. and Paul, K. M., Verhandl. d. k. k. geol. R. Reichs.-Anst., p. 135. 1863. Phoca holitschensis. Bruhbl, C. B., Mittheil. A. d. k. k. Zool. Institute der Universitit Pest, pls. 1-2. Wien, 1860.—Zittel, I. v., Traité de Paléon- tologie, pt. 1, Paleozoologie, vol. 4, p. 689 (translation Barrois). Paris, 1894.—Roger, O., Berich naturwiss. Vereins f. Schwaben und Neu- burg (a. V.), vol. 32, p. 74. Augsburg, 1896.—Toula, F., Beitrage z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, pp. 49, 50, 51, 54. Wien und Leipzig, 1898—Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 385. Berlin, 1897. Phoca hatitschensis. Allen, J. A., Mise. Publ. no. 12, U. 8S. Geol. and Geog. Surv. Terr., Dept. Interior, pp. 477, 479. Washington, D. C., 1880. Phoca hatlitchensis. Van Beneden, P. J.. Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 24, 26. Brussels, 1877. Phoque. Cuvier, G., Recherches sur les ossemens fossiles, vol. 8, pt. 1, p. 456. Paris, 1836. Phoca viennensis antiqua. Blainville, Ostéographie ou description icono- graphique, vol. 2, pp. 42, 51, Atlas, vol. 2, pl. 10, fig. 1. Paris, 1839-64. —Pietet, F. J., Traité de Paléontologie (2), vol. 1, p. 232. Paris, ava. 120 University of California Publications in Geology [Vou. 18 1853.—Toula, F., Beitrage z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, pp. 49, 50. Wien und Leipzig, 1898. Phoca viennensis. Gervais, P., Zoologie et paléontologie francaises (2), p. 274. Paris, 1859—Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 385. Berlin, 1897. Phoca antiqua. Suess, E., Sitzungsber. math.-naturw. Cl. d. k. Akad. Wissensch., vol. 54, p. 11. Wien, 1866. (Holitsch.)—Peters, K. F., Sitzungsber. math.-naturw. Cl. d. k. Akad. Wissensch., vol. 55, pt. 2, p. 111. Wien, 1867. TYPE LocALITY.—Holitsch, Nyitra County, Hungary, on the right bank of the Morava River about 30 miles northeast of Vienna. Upper Miocene. : PHOCA PONTICA Hichwald Phoca pontica. Hichwald, E., Lethaea Rossica ou Paléontologie de la Russie, vol. 3, pp. 391-400, 1853, Atlas, pl. 13, figs. 1-37. Stuttgart, 1852.—Lartet, E., Bull. Soc. Geol. de France (2), vol. 21, p. 260. Paris, 1864. (Peninsulas of Kertch and Taman.)—Peters, K. F., Sitzungsber. math.-naturw. Cl. d. k. Akad. Wissensch., vol. 55, pt. 2, pp. 110, 111. Wien, 1867. (Part.)—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 26, 74. Brussels, 1877.— Allen, J. A., Mise. Publ. no. 12, U. S. Geol. and Geog. Surv. Terr., Dept. Interior, pp. 477, 479. Washington, D. C., 1880.—Calvert, F., and Neumayr, M., Denkschr. k. Akad. Wissensch. Wien. math. natur- wiss. Cl., vol. 40, pp. 361, 363, 365. Wien, 1880. (Hrenkoi, Turkey.)— Toula, F., Beitrage z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, pp. 49, 50, 51, 53, 54. Wien und Leipzig, 1898.— Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 385. Berlin, 1897. Ph(oca) pontica. Nordmann, A. v., Palaeontologie Sudrusslands, pt. 4, pp. 299, 318, Atlas, pl. 22, figs. 4-5; pl. 23, figs. 4-5. Helsingfors, 1860. —Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896. TYPE LOCALITY.—In ferruginous clay on Mount Mithridates, near Kertch, and in limestone formation on promontory of Akbouroun, Province of Taurida, Russia. Upper Miocene. PHOCA WYMANI Leidy Phocidae. Wyman, J., Am. Jour. Sci. (2), vol. 10, p. 229. 1850. (Part.) Phoca wymani. Leidy, J., Smithson. Contrib. to Knowledge, vol. 6, p. 8. Washington, D. C., 1854. (Part.)—Allen, J. A., Misc. Publ. no. 12, U.S. Geol. and Geog. Surv. Terr., Dept. Interior, p. 472. Washington, D. C., 1880.—Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896. TYPE LOCALITY.—In the ravine at the eastern extremity of Richmond, and in the neighborhood of the penitentiary, Henrico County, Virginia. Middle Miocene. Ue PHOCA sp. B Kellogg . “*Seals.’’ Miller, L. H., Univ. Calif. Publ. Bull. Dept. Geol., vol. 7, no. 5, p- 115. Berkeley, 1912. (San Pedro.) 1922] Kellogg: Pinnipeds from Miocene and Pleistocene Deposits 121 Phoca sp. B. Kellogg, R., Univ. Calif. Publ., Bull. Dept. Geol., vol. 13, no. 4, pp. 45-46. Berkeley, 1922. TYPE LOCALITY.—In shell bearing stratum about six feet above beach level at the point where cliff begins on approaching the town of La Jolla from the north. Presumably the lower level of the upper San Pedro beds near La Jolla, San Diego County, California. Pleistocene. PHOCA, sp. A Kellogg Phoca, sp. A. Kellogg, R., Univ. Calif. Publ., Bull. Dept. Geol., vol. 13, no. 4, p. 45. 1922. TYPE LOCALITY.—Northwest end of Tejon Hills, Kern County, California, in unsurveyed N.E. 4, Section 23, Township 32 South, Range 29 East (Mount Diablo Base and Meridian). In Santa Margarita white clayey sands, 100 feet below Chanac formation. Ostrea titan and Pecten crassicardo, ete., occur in a bed stratigraphically but a short distance below this horizon. Upper Miocene. PHOCA, near HISPIDA Schreber Calocephalus vitulinus. Brown, T., Trans. Roy. Soc. Edinburgh, vol. 24, pt. 3, p. 629. 1867. (Hrrol.) Phoca vitellinus. Howden, J. G., Trans. Edinburgh Goel. Soc., vol. 1, p. 141. 1868. (Montrose.) Phoca hispida. Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 32, p. 6. Brussels, 1871—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, p. 28. Brussels, 1877.— Loénnberg, E., Arkiv for Zoologi utgifvet af K. Svenska Vetenskaps- akademien i Stockholm, Uppsala and Stockholm, vol. 4, no. 22, pp. 3-16, figs. 1-2. 1908. (Litorhina clay.)—Lonnberg, E., Fauna och Flora, Popular Tidskrift for Biologi, Haft 4, pp. 165-173, figs. 1-2. 1908.—Lonnberg, E., Arkiv for Zoologi utgifvet af K. Svenska Vetenskapsakademien i. Stockholm, Uppsala and Stockholm, vol. 6, no. 3, pp. 9-12. 1910. (Fresh water clay.)—Turner, W., The marine mammals in the anatomical museum of the University of Edinburgh, pt. 3, pp. 185-186. London, 1912. (Puggiston; Montrose; Errol.) Ph(oca) hispida foss. Roger, O., Berich naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896.—Toula, F., Beitrige z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, p. 55. Wien und Leipzig. 1898. (Pusa) hispida foss. Trouessart, E. L., Catalogus mammalium tam viven- tium quam fossilium, vol. 1, p. 386. Berlin, 1897. TYPE LocALity.—In arctic shell clay of brickfield near Errol, Scotland. Pleisto- cene. Genus PHOCANELLA Van Beneden Phocanella. Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 41, p. 799. Brussels, 1876. Type, Phocanella pumila Van Beneden. 122 University of California Publications in Geology | Vou. 18 PHOCANELLA PUMILA Van Beneden Phocanelia pumila. Van Beneden, P. J., Bull. Acad. Roy. Sei. de Bel- gique (2), vol. 41, no. 4, p. 799. Brussels, 1876——Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 70-71, pl. 14, figs. 1-12. Brussels, 1877.—Mourlon, M., Bull. Acad. Roy. des Sci., des Léttres et des Beaux-Arts de Belgique (2), vol. 43, no. 5, p. 607. Brussels, 1877. (Deurne et Borgerhout.)—Allen, J. A., Mise. Publ. no. 12, U. 8. Geol. and Geog. Surv. Terr., Dept. Interior, p. 479. Washington, D. C., 1880.—Roger, O., Berich naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 75. Augsburg, 1896.—Toula, F., Beitrage z. Paliont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, pp. 52, 55. Wien und Leipzig, 1898.—Trouessart, EH. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 387. Berlin, 1897.—Palmer, T. S., North Am. Fauna, no. 23, p. 533. Washington, D. C., 1904. TypPE LocaLiry.—In the third section, Antwerp, Basin, Belgium. Middle Pliocene. PHOCANELLA MINOR Van Beneden Phocanella minor. Van Beneden, P. J., Bull. Acad. Sci. de Belgique (2), vol. 41, no. 4, p. 799. Brussels, 1876—Van Beneden, P. J., Ann. Mus. Roy. Hist Nat. de Belgique, vol. 1, pt. 1, pp. 71-72, pl. 14, figs. 13-25. Brussels, 1877.—Mourlon, M., Bull. Acad. Roy. des Sci., des Léttres et des Beaux-Arts de Belgique (2), vol. 43, no. 5, p. 608. Brussels, 1877. (Borgerhout et Vieux-Dieu?.)—Allen, J. A., Mise. Publ. no. 12, U.S. Geol. and Geog. Surv. Terr., Dept. Interior, p. 479. Washington, D. C., 1880.—Newton, E. T., Quar. Jour. Geol. Soc., vol. 46, p. 447, pl. 18, figs. 4a, 4b. London, 1890.—Newton, E. T., Vertebrata of Pliocene deposits of Britain, Mem. Geol. Surv. United Kingdom, pp. 19-20. London, 1891. (Red Crag Nodule bed, Foxhall.)—Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, Dp: (0s Augsburg, 1896.—Toula, F., Beitrige z. Palaont. u. Geol. Osterreich- Ungarns u. d. Orients, vol. 11, pp. 52, 54, 55. Wien und Leipzig, 1898. —Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 387. Berlin, 1897.—Palmer, T. 8., North Am. Fauna, no. 23, p. 533. Washington, D. C., 1904. TYPE LocaLity.—In the third section and at Moortsel, Antwerp basin, Bel- gium. Middle Pliocene. . < PHOCID near? HALICHOERUS GRYPUS “‘Fossil seal.’’ Thompson, A. W., Jour. Anat. and Phys., vol. 13, pp. 318-321. London, 1879. (Dunbar.)—Turner, W., The marine mam- mals in the anatomical museum of the University of Edinburgh, pt. 3, p. 186, text fig. p. 187. London, 1912. Typr LocaLtiry.—tIn brick clay at Dunbar, Haddington County, Scotland. Pleistocene. 1922) Kellogg: Pinnipeds from Miocene and Pleistocene Deposits 128 Genus LEPTOPHOCA True Leptophoca. True, F. W., Proce. U. 8. Nat. Mus., vol. 30, no. 1475, p. 835. Wash- ington, D. C., 1906. Type, Leptophoca lenis True. LEPTOPHOCA LENIS True ** Fossil scal.’’ True, F. W., Science, n.s., vol. 22, no. 572, p. 794. 1905. Leptophoca lenis. True, F. W., Proc. U. 8. Nat. Mus., vol. 30, no. 1475, pp. 836-840, pls. 75-76. Washington, D. C., 1906. Typr LocaLity.—In the Calvert Cliffs bordering on Chesapeake Bay, Calvert County, Maryland; between Chesapeake Beach and Plum Point, and in what is known as Zone 10. Middle Miocene. Genus PAGOPHOCA Trouessart Pagophoca. Trouessart, EK. L., Catalogue mammalium tam viventium quam fossilium, Suppl, p. 287. Berlin, 1904. Type, Phoca groenlandica Eyrxleben. ype, g PAGOPHOCA, near GROENLANDICA (Erxleben) Seal. Jackson, C. T., Final Report Geol. and Mineral. New Hampshire, p- 94. Concord, 1844.—Proc. Acad. Nat. Sci., Phila., vol. 8, pp. 90-91, pl. 3. 1856. Phoca groenlandica. Logan, W. H., Geol. Surv. Canada, Montreal, p. 920, figs. 493a, 493b, on p. 965. 1863—Kinberg, J. G. H., Ofversigt af Kongl. Vetens, Akad. Forhandl., vol. 26, no. 1, pp. 13, 14, 15. Stockholm, 1869.—Leidy, J., Jour. Acad. Nat. Sci., Phila. (2), vol. 7, p. 415. 1869.—Van Beneden, P. J., Bull. Acad. Roy. Sei. de Belgique (2), vol. 32, no. 7, p. 7. Brussels, 1871.—Van Beneden, Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 28, 34. Brussels, 1877.— Dawson, J. W., Canadian Naturalist (2), vol. 8, p. 341. Montreal, 1878.—Allen, J. A., Mise. Publ. no. 12, U. 8. Geol. and Geog. Surv. Terr., Dept. Interior, pp. 474, 475. Washington, D. C., 1880.—Jentzsch, A., and Tenne, C. A., Zeitsch. deutsch. geol. Gesellsch., vol. 39, pp. 497, 498. 1887.—Gaudry, A., Compt. Rend. Acad. Sci. Paris, vol. 3, pp. 852, 353. 1890—Toula, F., Beitrage z. Paliont. u. Geol. Osterreich- Ungarns u. d. Orients, vol. 11, pp. 50, 53. Wien und Leipzig, 1898. Ph(oca) gronlandica foss. Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896. (Pagophilus) groenlandica foss. Trouessart, h. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 388. Berlin, 1897. Type LocALiry.—In marine mud, at a depth of thirty feet from surface, South Berwick, York County, Maine. Pleistocene. Genus CALLOPHOCA Van Beneden Callophoca. Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 41, no. 4, p. 798. Brussels, 1876. Type, Callophoca obscura Van Beneden. 124 University of California Publications in Geology [Vou. 18 CALLOPHOCA OBSCURA Van Beneden Callophoca obscura. Van Beneden, P. J., Bull. Acad. Roy. Sci. de Bel- gique (2), vol. 41, no. 4, p. 798. Brussels, 1876—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 65-67, pl. 11, figs. 1-13. Brussels, 1877—Mourlon, M., Bull. Acad. Roy. des Sci., des Léttres et des Beaux-Arts de Belgique (2), vol. 43, no. 5, p. 607. Brussels, 1877. (Deurne et Borgerhout.)—Allen, J. A., Misc. Publ. no. 12, U. 8. Geol. and Geog. Surv. Terr., Dept. Interior, p. 479., Washington, D. C., 1880.—Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburn (a. V.), vol. 32, p. 75. Augsburg, 1896.— Toula, F., Beitrage z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, pp. 52, 55. Wien und Leipzig, 1898.—Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p- 388. Berlin, 1899.—Palmer, T. 8., North Am. Fauna, no. 23, p. 153. Washington, D. C., 1904. Type LocaLiry.—In the third section, Antwerp Basin, Belgium. Middle Pliocene. Fossiz Remains INcoRRECTLY REFERRED TO THE PINNIPEDIA CARNIVORA PSEUDAELURUS? sp. Phoque. Blainville, H. M. D., Compt. Rend. Acad. Scei., Paris, vol. 5, no. 12, p. 426. 1837. Phoca, Toula, F., Beitrage z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, p. 48. Leipzig und Wien, 1898. TYPE LOCALITY. Sansan, Department of Gers, France. Middle Miocene. URSUS sp.? Phoque. Esper, J. Fr., Mag. Berlin Naturf. Freunde, vol. 5, p. 98, 1784.— Esper, J. Fr., Frankfurt Archiv, vol. 1, p. 77; vol. 2, p. 165. 1790.— - Cuvier, G., Recherches sur less ossemens fossiles (4), vol. 8, pt. 1, p. 453. Paris, 15356.—Blainville, H. M. D., Ostéographie ou deserip- tion iconographique, vol. 2, pp. 37-38. Paris, 1839-64.—Figuier, P., La terre avant le déluge, p. 441. Paris, 1874. TYPE LocALITy.—Gailenreuth in Bavaria and Kahlendorf in Aichstedt. Pleistocene. PERISSODACTYLA RHINOCEROTID gen. and sp.? Phoca. Monti, J.. De monumento diluviano in agro Bononiensi detecto, Bologna, 1719.—Cuvier, G., Recherches sur les ossemens fossiles (4), vol. 8, pt. 1, pp. 457,458. Paris, 1836.—Blainville, H. M. D., Ostéo- graphie ou description inconographique, vol. 2, p. 38. Paris, 1839-64. —Pictet, F., Traité de Paléontologie (2), vol. 1, p. 234. Paris, 1853. TYPE LocALITY.—Bologna, Italy. Middle Pliocene. 1922] Kellogg: Pinnipeds from Miocene and Pleistocene Deposits 125 ARTIODACTYLA RUMINANT gen. and sp. Morse. Duvernoy, G. L., Compt. Rend. Acad. Sci. Paris, pp. 494-495. 1837.—Blainville, H. M. D., Ostéographie ou description iconographique, vol. 2, p. 46; Atlas, vol. 2, pl. 10, fig. 5. Paris, 1839-64. TYPE LOCALITY.—In formation of white rock, south and east of Oran in Algeria, Africa. ?Lower Eocene. PROBOSCIDEA ? ELEPHAS PRIMIGENIUS Morse. Lebnitz, G. W., Protogaea, cap. 33-34, Gottingen, 1749.—Georgi, J. G., Geog.-physik. u. naturh. Beschr. d. Russischen Reichs, vol 3, pp. 3890, 591. Koenigsberg, 1797-1802.—Cuvier, G., Recherches sur les ossemens fossiles (4), vol. 8, pt. 1, p. 457. Paris, 1836.—Blainville, H. M. D., Ostéographie ou description iconographique, vol. 2, p. 37. Paris, 1839-64. TYPE LOCALITY.—Siberia. Pleistocene. SIRENIA SIRENID? gen. and sp.? P(hoca) aegyptiaca antiqua. Blainville, H. M. D., Ostéographie ou de- scription iconographique, vol. 2, pp. 43, 51; Atlas, vol. 2, pl. 10, fig. 2. Paris, 1839-64.—Toula, F., Beitrage z. Paliont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, p. 49. Wien und Leipzig, 1898. TYPE LocALITY.—In white caleareous limestone on right bank of valley of the Nile, Egypt. ? Middle Eocene. HALIANASSA? sp. Trichechus rosmarus. Schuebler, Neues Jahrbuch fiir Mineralogie, pp. 79-80. 1832. ‘““Wallross.’’ Jaeger, G. F., Ueber die fossilen Saiugethiere, welche in Wiirtemberg aufgefunden worden sind, pt. 1, pp. 1-2, pl. 1, figs. 1-3. Stuttgart, 1835. Trichechus molassicus. Bronn, H. G., Neues Jahrbuch fiir Mineralogie, p. 732. Stuttgart, 1837—Bronn, H. G., Lethaea Geognostica, vol. 2, p. 840. Stuttgart, 1838. Trichecus. Jaeger, G. F., Uber die fossilen Saugethiere welche in Wiir- temberg in verschiedenen formationen aufgefunden worden sind, pt. 2, p. 203. Stuttgart, 1839. Tr(ichecus) molassicus. Giebel, C. G., Fauna der Vorwelt, vol. 1, pp. 222-223. Leipzig, 1847.—Pictet, F. J., Traité de Paléontologie (2), vol. 1, p. 234. Paris, 1853. 126 University of California Publications in Geology (Vou. 13 “‘Morse.’’ Blainville, H. M. D., Ostéographie ou description icono- ° graphique, vol. 2, p. 44. Paris, 1839-64. TYPE LocALiry.—Stone pit of Baltringen near Biberach, Wurttemberg, Ger- many. Middle Miocene. METAXYTHERIUM CUVIERI Christol Phoque. Cuvier, G., Recherches sur les ossemens fossiles (4), vol. Sa ptemle pp. 454-455; Atlas, vol. 2, pl. 220, figs. 24-26, 28-29. Paris, 1836.— Blainville, H. M. D., Ostéographie ou description iconographique, vol. 2, pp. 38-41. Paris, 1839-64. Metarytherium. Christol, J., Ann. Sci. Nat. Paris (2), vol. 15, pp. 307— 331. 1841. Phoca fossilis. Pictet, F., Traité de Paléontologie (2), vol. 1, p. 232. Paris, 1553.—Gervais, P., Zoologie et Paléontologie francaises (2), p. 272. Paris, 1859.—Van Beneden, P. J., Bull. Acad. Roy. Sei. de Belgique (2), vol. 32, no. 7, p. 5. Brussels, 1871.—Toula, F., Beitrage z. Paliont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, p. 48. Wien und Leipzig, 1898. TYPE LocALity.—In the sandstone of Angers, Department of Maine-et-Loire,. France. ? Middle Miocene. ODONTOCETI SQUALODONTIDAE NEOSQUALODON AMBIGUUS (Von Meyer) Phoca ambiqua. Minster, G. G., Neues Jahrbuch fiir Mineralogie, p. 447. Stuttgart, 1855. (Nomen nudwm.)—Bronn, H. G., Lethaea Geognos- tica, vol. 2, p. 840. Stuttgart, 1838—Meyer, H. von, Beitrige zur Petrefaktenkunde, vol. 3, p. 1, pl. 7, figs. 1-6. Bayreuth, 1840.— Meyer, H. v., Neues Jahrbuch fiir Mineralogie, p. 96. Stuttgart, 1840.—Giebel, C. G., Fauna der Vorwelt, vol. 1, p. 224. Leipzig, 1847. —Pictet, F. J., Traité de Paléontologie (2), vol. 1, p. 233, pl. 6, figs. 1-3. Paris, 1853.—Guiseardi, G., Atti della R. Acad. d. Sci. Fisiche e Matem., vol. 5, no. 6, p. 7. Naples, 1873—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, pp. 24, 25. Brussels, 1877.—Zittel, K. v., Traité de Paléontologie, Mamm., vol. 4, p. 690. Paris, 1894.—Roger, O., Berich naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 77. Augsburg, 1896.—Toula, F., Beitrage z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, p. 54. Wien und Leipzig, 1898 —Abel, O., Mem. Mus. Roy. d’Hist. Nat. de Belgique, vol. 3, pp. 46, 66 (footnotes). Brussels, 1905. TYPE LocAaLity.—Tertiary marls of the Osnabruck basin near Btinde, Olden- burg, Germany. Middle Oligocene. SQUALODON SCILLAE (Agassiz) ‘*Pogssil.’’? Scilla, A., La Vana Speecvlazione disingannata dal Senso. Lettera risponsiva circa i corpi Mariné, che Petrificati fi trouana in 1922] Kellogg: Pinnipeds from Miocene and Pleistocene Deposits 127 varij loughi terrestri, p. 123, pl. 12, fig. 1. Naples, 1670.—Scilla, A., De Corporibus Marinis Lapidescentibus quae defossa reperiuntur, p. 47, pl. 12, fig. 1. Rome, 1747.—Scilla, A., De Corporibus Marinis Lapidescentibus quae defossa reperiuntur (2nd ed.), p. 54, pl. 12, fig. 1. Rome, 1759. Phocodon scillae Agassiz, L. Valentin’s Repertorium Anat. et Physiol. Berne et St. Gallen, vol. 6, p. 236. 1841. (Considered tooth a phocid. ) —AZittel, K. v., Handbuch der Palaeontologie, vol. 4, p. 170. 1893.— Palmer, T. 8., North Am. Fauna, no. 23, p. 533. Washington, D. C., 1904. Phoca? melitensis antiqua. Blainville, H. M. D., Ostéographie ou deserip- tion iconographique, vol. 2, p. 51; Atlas, vol. 2, pl. 10, fig. 4. Paris, 1839-64.— Meyer, H. v., Neues Jahrbuch f. Mineralogie, p..242. Stutt- gart, 1841.—Toula, F., Beitrige z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, pp. 49, 50. Wien und Leipzig, 1898. P(hoca) dubia melitensis. Blainville, H. M. D., Ostéographie ou deserip- tion iconographique, vol. 2, p. 46. Paris, 1839-64. Zeuglodon. Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, p. 24. Brussels, 1877.—Gregory, W. K., Bull. Amer. Mus. Nat. Hist., vol. 27, p. 411. New York, 1910. ““Squalodont.’’ Allen, J. A., Bull. U. 8. Geol. and Geog. Surv. Terr., vol. 6, no. 3, pp. 420, 448, 456. Washington, D. C., 1882. Sq(walodon) (Phocodon) scillae. Zittel, K. v., Handbuch der Palaeon- tologie, vol. 4, p. 171. 1893. TYPE LOCALITY.—Tophus of Malta. Miocene. SQUALODON DEBILIS (Leidy) Phoca debilis. Leidy, J., Proc. Acad. Nat. Sci. Phila., vol. -8, p. 265. 1856.—Bronn, H. G., Neues Jahrbuch f. Mineralogie, p. 252. 1858— Cope, HE. D., Proc. Acad. Nat. Sci. Phila., vol. 19, p. 1538. 1867.— Leidy, J.. Jour. Acad. Nat. Sci. Phila. (2), vol. 7, p. 415, pl. 28, figs. 12-13. 1869.—Allen, J. A., Mise. Publ. no, 12, U. S. Geol. and Geog. Surv. Terr., p. 473. Washington, D. C., 1880.—Roger, O., Berich naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896.—Toula, F., Beitrige z. Paliont. u. Geol. Osterreich- Ungarns u. d. Orients, vol. 11, p. 49. Wien und Leipzig, 1898.— Trouessart, E. L., Catalogus mammalium tam viventium quam fos- silium, vol. 1, p. 388. Berlin, 1897. Squalodon debilis. Hay, O. P., Bull. U. 8. Geol. Surv. no. 179, p. 589. Washington, 1902. TYPE LocALITy.—Sands of Ashley River, South Carolina. Upper Miocene. SQUALODON sp.? Phoca pedronii. Gervais P., Compt. rend. Acad. Sci. Paris, vol. 28, p. 644. 1849.—Gervais, P., Zoologie et Paléontologie francaises (2), p. 274, pl. 41, fig. 1. Paris, 1859.—Cope, E. D., Proce. Acad. Nat. Sci. Phila., vol. 19, p. 153. 1867.—Toula, F., Beitrage z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, p. 49. Wien und Leipzig, 1898. 128 University of California Publications in Geology [Vou. 18 Phoca pedroni. Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 32, no. 7, p. 5. Brussels, 1871.—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, p. 25. Brussels, 1877.— Allen, J. A., Mise. Publ. no. 12, U. S. Geol. and Geog. Surv. Terr., p- 477. Washington, D. C., 1880. (Pristiphoca) pedroni. Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 379. Berlin, 1899. TYPE LOCALITY. From Leognan near Bordeaux, France. Middle Miocene. 2SQUALODON MIRABILIS (Von Meyer) Pachyodon mirabilis. Meyer, H. v., Neues Jahrbuch ftir Mineralogie, p. 414. Stuttgart, 1838.—Miunster, G. G., Beitrage zur Petrefaktenkunde, vol. 3, p. 2, pl. 8. Bayreuth, 1840.—Giebel, C. G., Fauna der Vorwelt, p. 225. Leipzig, 1847.—Pictet, F. J., Traité de Paléontologie (2), vol. 1, p. 233. Paris, 1853.—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, p. 25. Bussels, 1877.—Palmer, T. S., North Am. Fauna, no. 23, p. 494. Washington, D. C., 1904. TypPE LocaLiry.—Moeskirch, Baden, Germany. Middle Miocene. SQUALODON MODESTUS (Leidy) Phoca modesta. Weidy, J., Jour. Acad. Nat. Sei. Phila. (2), vol. 7. p. 415, pl. 28, fig. 14. 1869.—Allen, J. A., Mise. Publ. no. 12, U. S. Geol. and Geog. Sury. Terr., p. 474. Washington, D. C., 1880.—Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896.—Toula, F., Beitrige z. Paliont. u. Geol. Osterreich- Ungarns u. d. Orients, vol. 11, p. 53. Wien und Leipzig, 1898.— Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 388. Berlin, 1897. Squalodon? modestus. Hay, O. P., Bull. U. 8. Geol. Surv., no. 179, p. 589. Washington, 1902. (Hocene.) Type LocaLiry.—Ashley River Phosphate deposits, South Carolina. Upper Miocene. SQUALODON RUGIDENS (H. v. Meyer) Phoca? rugidens. Meyer, H. v., Neues Jahrbuch fiir Mineralogie, p. 309. Stuttgart, 1845.—Meyer, H. v., Neues Jahrbuch fiir Mineralogie, p. 201. Stuttgart, 1850—Meyer, H. v., Berich. Mittheil. v. Freunden Naturwiss. in, Wien, vol. 7, p. 45. 1851. (Tegel von Baden near Vienna.)—Pictet, F. J., Traité de Paléontologie (2), vol. 1, p. 233. Paris, 1853.—Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, p. 24. Brussels, 1877.—Allen, J. A., Mise. Publ. no. 12, U. 8. Geol. and Geog. Surv. Terr., Dept. Interior, p. 477. Washington, D. C., 1880.—Toula, F., Beitrige z. Paliont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, pp. 49, 51. Wien und Leip- zig, 1898. Ph(oca) rugidens. Giebel, C. G., Fauna der Vorwelt, vol. 1, p. 224, Leipzig, 1847.—Guiscardi, G., Soc. Reale di Napoli, Atti dell’Accad. delle sci. fisiche e matem., vol. 5, no. 6, p. 9. Naples, 1873. Pristiphoca? rugidens. Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 380. Berlin, 1897. TYPE LOCALITY.—Neudorfl on the March River near Presburg in Hungary. Middle Miocene. 1922] Kellogg: Pinnipeds from Miocene and Pleistocene Deposits 129 PHYSETERIDAE ?SCALDICETUS GRANDIS Du Bus ? Phoca sp. Costa, O. G., Paleontologia del regno di Napoli, pt. 1, pp. 12-14, pl. 1, fig. 1. Naples, 1850.—Flores, E., Atti della Accademia Pontaniana, vol. 35, no. 18, p. 40. Naples, 1895. Physodon leccense. Capellini, C. G., Mem. dell’Acead. delle sci. dell’ Instituto di Bologna (3), vol. 9, fase. 2, pp. 246-247. 1878. ?Scaldicetus grandis. Abel, O., Mem. Mus. Roy. Hist. Nat. Belgique, vol. 3, p. 68. Brussels, 1905. TYPE LOCALITY.—From ‘‘Marna ealeare’’ of Lecce, near Otranto, in south- eastern Italy. Miocene. SCALDICETUS sp. “*Phoque.’’ Gervais, P., and Serres, M. de, Annales Sei. Nat. Paris (3), vol. 8, p. 225, footnote [Uchaux (Vaucluse) errore]. 1847.—Gervais, P., Zoologie et Paléontologie frangaises (1), pl. 8, fig. 8. Paris, 1848-52.—Gervais, P., Bull. Soc. Geol. de France (2), vol. 10, p. 311. Paris, 1853. Otaria? prisca. Gervais, P., Zoologie et Paléontologie francaises (2), p. 275, pl. 8, fig. 8. Paris, 1859.—Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique (2), vol. 32, no. 7, p. 5. Brussels, 1871.— Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, p. 57. Brussels, 1877.—Allen, J. A., Mise. Publ. no. 12, U. S. Geol. and Geog. Surv. Terr., p. 218. Washington, D. C., 1880.—Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 76. Augsburg, 1896. Phoca sp. Cope, EH. D., Proce. Acad. Nat. Sci. Phila., vol. 19, p. 153. 1867. Phoca gervaisi. Rouault, M., Compt. Rend. Acad. Sei. Paris, vol. 47, p. 100. 1858. (Shell marl of S. Juvat.)—Gervais, P., Journal de Zoolo- gie, vol. 1, p. 67. Paris, 1872.—Toula, F., Beitrige z. Paliont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, p. 50. Wien und Leipzig, 1898. Squalodon [bariensis]. Gervais, P., and Van Beneden, P. J., Ostéographie des Cétacés vivants et fossiles; p. 434, pl. 28, fig. 10. Paris, text 1880, Atlas 1868-79. Squal(odon) grateloupii. Roger, O., Bericht naturwiss. Vereins. f. Schwaben und Neuburg (a. V.), vol. 32, p. 76. Augsburg, 1896. Scaldicetus sp. Abel, O., Mem. Mus. Roy. Hist. Nat. Belgique, vol. 3, p. 28, footnote. Brussels, 1905. TYPE LOCALITY.—Sandstone of Uzes, Department of Gard, France. Upper Miocene. ?SCALDICETUS sp. Phoca larreyi. Rouault, M., Compt. Rend. Acad. Sci. Paris, vol. 47, p. 100. 1858. (Le Quiou.)—Gervais, P., Journal de Zoologie, vol. 1, p. 67. Paris, 1872.—Toula, F., Beitrage z. Paliont. u. Geol. Osterreich- Ungarns u. d. Orients, vol. 11, p. 50. Wien und Leipzig, 1898. TypPrE LocALIry.—In the shell marl of Le Quiou, Bretagne, France. Miocene? 130 University of California Publications in Geology | Vou. 13 ZIPHIIDAE ? CETORHYNCHUS CHRISTOLI Gervais Phoca occitana. Gervais, P., Bull. Soc. Geol. de France (2), vol. 10, p. 311. Paris, 1853. (Part: Poussan.) Prisitiphoca occitana. Gervais, P., Zoologie et Paléontologie francaises (2), p. 273, 274, pl. 38, fig: 8 (Languedoc, Poussan); pl. 8, fig. 7 (Fausson). Paris, 1859. (Part.)—Allen, J. A., Mise. Publ. no. 12, U.S. Geol. and Geog. Surv. Terr., Dept. Interior, p. 477. Washington, D. C., 1880. (Part.) TYPE LOcALITY.—Poussan and Fausson, in the Department of Herault, France. Miocene. DELPHINIDAE DELPHINODON LEIDYI Hay Seal. Wyman, J., Am. Jour. Sci. (2), vol. 10, p. 229, 232, fig. 1-8. 1850. (Part. ) Phoca wymani. Leidy, J., Smithson. Contrib. to Knowledge, vol. 6, p. 8. Washington, D. C., 1854—Leidy, J., Proc. Acad. Nat. Sei. Phila., vol. 8, p. 265. 1856. (Part.)—Bronn, H. G., Neues Jahrbuch f. Miner- alogie, p. 252. Stuttgart, 1858—Leidy, J., Jour. Acad. Nat. Sci. Phila. (2), vol. 7, p. 415, pl. 30, fig. 12. 1869—Allen, J. A., Misc. Publ. no. 12, U. 8. Geol. and Geog. Surv. Terr., pp. 470, 471, 473, 480. Washington, D. C., 1830—Toula, F., Beitrage z. Palaont. u. Geol. Osterreich-Ungarns u. d. Orients, vol. 11, p. 49. Wien und Leipzig, 1898.—Trouessart, E. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 388. Berlin, 1897. Squalodon wymanii. Cope, E. D., Proc. Acad. Nat. Sci. Philo., vol. 19, p. 152. 1867—Allen, J. A., Misc. Publ. no. 12, U. S. Geol. and Geog. Surv. Terr., p. 473. Washington, D. C., 1880 Delphinodon wymani. Leidy, J., Jour. Acad. Nat. Sci. Phila. (2), vol. 7, p-. 426. 1869.—True, F. W., Proc. Biol. Soc. Washington, vol. 24, pp. 37-38. 1911. Delphinodon leidyi. Hay, O. P., Bull. U. 8. Geol. Surv. no. 179, p. 591. Washington, 1902. ?Acrodelphis sp. Abel, O., Mem. Mus. Roy. Hist. Nat. Belgique, vol. 3, pp. 138. Brussels, 1905. TYPE LOocALITY.—Shockoe Creek.ravine at base of Church Hill, near Rich- mond, Virginia. Upper Miocene. ORDINAL POSITION UNCERTAIN DOLPHIN? Ph(oca) occitana. Gervais, P., Zoologie et Paléontologie francaises (2), p- 273, pl. 20, figs. 5, 6. Paris, 1859. Pristiphoca occitana. Wan Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, p. 25. Brussels, 1877. (Part.) 1922] Kellogg: Pinnipeds from Miocene and Pleistocene Deposits 131 “*Dauphin?’’ Deperet, C., Arch. Mus. d’Hist. Nat. Lyon, vol. 4, p. 272. 1887. (Molasse helvetienne.) TYPE LOCALITY.—Shell marl of Romans, Department of Dréme, France. Middle Miocene. ? CETACEAN, gen. et sp.? ““Phocas.’’ WVandelli, A. A., Hist.e Mem. d. Acad. Real. d. Sei. de Lisboa, Vole I pte i pp 20l 297, plo, ue. LO) L83T. “*Phoque.’’ Gervais, P., Zoologie et Paléontologie francaises (2), p. 274. Paris, 1859.— Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Bel- gique, vol. 1, pt. 1, p. 25. Brussels, 1877. TYPE LOCALITY.—In upper sedimentary deposits on the Cape of Hspichel beyond the Tejo and at the site of Adica about four leagues from Lisbon, Portu- gal. ‘‘Primeiro Terreno marinho no Calcareo grosseiro marinho.’’ ? PHOCID, gen. et sp.? ““Foca.’’ Tozzeti, G. T., Relazioni d’aleuni Viaggi fatti in diverse parti della Toseane per osservare le produxioni naturali, vol. 10, p. 394, and vol. 12, p. 200. Wirenze, 1768-69. ““Phoque.’’ Cuvier, G., Recherches sur les ossemens fossiles (4), vol. 8, pt. 1, p. 463. Paris, 1836——Blainville, H. M. D., Ostéographie ou description iconographique, vol. 2, p. 38. Paris, 1839-64. TYPE LOCALITY.—Caverns on the sea coast near Pisa, Province of Tuscany, Italy. Upper Pliocene? ? PHOCID, gen. et sp. “‘Loup marin.’’ Boue, A., Journal de géologie, vol. 3, no. 9, pp. 30-31. Paris, 1831. **Phoque.’’ SBlainville, H. M. D., Ostéographie ou description icono- graphique, vol. 2, p. 41. Paris, 1839-64.—Pictet, F. J., Traité de Paléontologie (2), vol. 1, p. 232. Paris, 1853——Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, p. 25. Brussels, 1877. TYPE LOCALITY.—In a calcareous formation at Wollersdorf ‘‘analogous to the ‘erayeuse de Maestricht,’ Germany.’’ Upper Cretaceous? ? CETACEAN Otaria leclercii. Delfortrie, E., Actes de la Societe Linneenne de Bor- deaux (3), vol. 8, pp. 385-386, figs. 2a, 2b, 2c, 2d. 1872.—Gervais, P., Journal de Zoologie, vol. 1, p. 327, figs. 2a, 2b, 2c, 2d. Paris, 1872.— Van Beneden, P. J., Ann. Mus. Roy. Hist. Nat. de Belgique, vol. 1, pt. 1, p. 25. Brussels, 1877—Allen, J. A., Misc. Publ. no. 12, U. 8S. Geol. and Geog. Surv. Terr., Dept. Interior, p. 218. Washington, D. C., 1880.—Toula, F., Beitrige z. Palaont. u. Geol. Osterreich-Ungarns, vol. 11, pp. 51, 55. Wien und Leipzig, 1898.—True, F. W., Prof. Paper no. 59, U. 8S. Geol. and Geog. Surv., Dept. Interior, p. 147. Washing- ton, D. C., 1909. 182 University of California Publications in Geology [Vou. 18 (Mesotaria) leclercii. Roger, O., Bericht naturwiss. Vereins f. Schwaben und Neuburg (a. V.), vol. 32, p. 74. Augsburg, 1896.—Trouessart, EH. L., Catalogus mammalium tam viventium quam fossilium, vol. 1, p. 378. Berlin, 1897.. TYPE LOCALITY.—Bone breccia of Saint-Medard-en-Jalle, near Bordeaux, France. Upper Oligocene. Transmitted December 13, 1919. x May 10, 1922 THE BRIONES FORMATION OF MIDDLE CALIFORNIA ae BY _ PARKER D. TRASK UNIVERSITY OF CALIFORNIA PRESS Se: BERKELEY, CALIFORNIA es: 1922 s ¢ ~ = a GEOLOGICAL SCIENCES.—Anprew C. Lawson, Editor. Price, volumes 1-7, $3.50 17. Notes on the Copper Ores at Ely, Nevada, by Alfred R. Whitman 2, LOC 18. Skull and Dentition of the Mylodont Sloths of Rancho La Brea, by Chester Stock. 15ce 19. Tertiary Mammal Beds of Stewart and Ione Valleys in West-Central Neyada, by John Py Buwal da’ -.-2--5.-0-.:.0.-t:-ccecdecstopeancnnseadecosneteton Proceas inten ean We dn Ce ee rr 30¢ 20. Tertiary Echinoids from the San Pablo Broun of Middle California, by William 8. wens P<, ee a ee Mn i ERE it TN 10¢- 21. An Occurrence of Mammalian Remains in a Pleistocene Lake Deposit at Astor e . Is the Boulder ‘‘Batholith’’ a Laccolith? A Problem in Ore-Genesis, by Andrew . Note on the Faunal Zones of the Tejon Group, by Roy HE. Dickerson -......-...-s.es-css-0-0 z . Teeth of a Cestraciont Shark from the Upper Triassic of Northern California, by . Bird Remains from the Pleistocene of San Pedro, California, by Loye Holmes Miller. . Tertiary Echinoids of the Carrizo Creek Region in the Colorado Desert, by William . Fauna of the Martinez Eocene of California, by Roy Ernest Dickerson ...........--:----- . Descriptions of New Species of Fossil Mollusca from the Later Marine Neocene of . The Fernando Group near Newhall, California, by Walter A.. English .........2.-..-------- . Ore Deposition in and near Intrusive Rocks by Meteoric Waters, by Andrew C. . The Agasoma-like Gastropods of the California Tertiary, by Walter A. English........ . The Martinez and Tejon Eocene and Associated Formations of the Santa Ana . The Oceurrence of Tertiary Mammalian Remains in Northeastern Nevada, by John . Remains of Land Mammals from Marine Tertiary Beds in the Tejon Hills, Cali- . The Martinez Eocene and Associated Formations at Rock Creek on the Western . A Proboscidean Tooth from the Truckee Beds of Western Nevada, by John P. UNIVERSITY OF CALIFORNIA PUBLICATIONS _ WILLIAM WESLEY & SONS, LONDON Ss : Agent for the series in American Archaeology and Ethnology, Botany, Geologi rs 7% Sciences, Physiology, and Zoology. Pa volumes 8 and following, $5.00. Volumes 1-12 completed; volume 13 in progress. list of titles in volumes 1 to 7 will be sent upon request. — VOLUME 8 Ge ALA WSO . .-20.-.oicndsctenesesedeoaseencgoett te cutecen doreseoeteestea sone teen (aoe ae ee eae er : Harold! C.Br yam .tccdcts tease .ece nce ecnsnsoscrepbeee aa eee tetccrc cues Aeegeinte tee PWG, TRG OW, 2k none noe Gnectnnennenennnapuniaccenesesenceneseenciaeiiestnecn sobs tdi Rivale ites gts tes eee California, by Bruce Martin 22.02 ccct.scsccses-:teee cheese there eee he UTA SOM A 22a natn ct saa nsuccanepsnenciesitansapbercocboenstestRaegtege Sonate tae PU Mountains, by Roy H. Dickerson, «..-.-...2cc-2.:.-cscsceceststecendeoqeceee-rer ade asenase eee (OP GUC) gk Cit Gee Oe A a ERE epee ORME EE are ee TEN er crc ie fornia, by Jolm .C., Merriam 2202122 oes. cenc-cscceccsctesteteesaesteassnndseeate ene eee a Border of the Mohave Desert Area, by Roy HE. 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Relations of the Invertebrate to the Vertebrate Faunal Zones of the Jacalitos and . A Review of the Species Pavo californicus, by Loye Holmes Miller . The Owl Remains from Rancho La Brea, by Loye “Holmes Miller -0i..svesccossseeceecensnneee . Two Vulturid Raptors from the Pleistocene of Rancho La Brea, by Loye epee . ~Notes on Capromeryx Material from the Pleistocene of Rancho La Brea, by re C. inees of North America, by John C, Merriam -.0.222.2222-:-0e--c-secee-sssseceesessonsennsceeenesessonezes 10e Bruce TW. Clark niece ic meee ccece web vcntas -ac Secale nese Pee INlommI ANG) Bic..ccnnnccaleccnnccnnnsanncecnndsass-cocasodlaateda s0oa scmeeaaeee eee Baer oe ee Etchegoin Formations in the North Coalinga Region, California, by Jorgen O. NOMI AIG, so: 2n..--n22 cack anna ane cen da conde sade pew Ee aae aoe epee ewecoaerct eee a MM CF Wo oece asses ccnencssactcennseqiconncseneccucecSesde ncbonceee codecs tale ae eee Chern er naan cn a cS a UNIVERSITY OF CALIFORNIA PUBLICATIONS BULLETIN OF THE DEPARTMENT OF GEOLOGICAL SCIENCES Vol. 13, No. 5, pp. 133-174, plates 1-8 May 10, 1922 THE BRIONES FORMATION OF MIDDLE CALIFORNIA BY PARKER D. TRASK CONTENTS PAGE Introduction and acknowledgments.........0...00..cccccccccccececececcveseevessevvesesvsseeveseeveeeeeveeeees 134 Areal distribution of Briones formation ...........00.00000.00ccccccceceee cee veteveeeveeeveeveeveteeseees 135 Description of the poauen se ct eae SR A EEE eee Se 136 AES aU a MR ne Sree Meare REM. vay ce OAINON re ce soot dsc cle cy ge cseudcounk co sce Ta de vonsdsditt iesdcayehosbeesastee . 139 Complete list of known species from the Briones with their geologic range.......... 141 Statistical summary of faunal list......0..000 cocci cecceeececeeeeeceseeseeveeceevesesevsttvesseeeseeeees 143 Relation of the Briones fauna to the Monterey fauma..........00...00000ccccecccecceeeeeeeeeees 144 Relation of the Briones fauna to the San Pablo fauna..............000.000ccceccecceeeeeees 144 ESCH EON OL SPECIES, rec. ..t-scuscdeencucsectuseoesssuesnessescsteusvessedossaverssesapstuneessesasesuetensveacusdaenss 147 We AP LUTE OM PV ATU eter tee nce tee eescac eta cad-eszeencen saayess sindcoa-ghsnbSiregsnegsosnendeacaveaneeahcnees 147 Pecten (Lyropecten) ricei, 1.SPii......cc ccc cccecceccecccesescsscscesecsserevseessestesstssstesesseates 148 Pecten (Lyropecten) vickeryl, D.SP...........ccccccceccssssseesecscesccatcetcssesccsecesecasseeteeees . 148 Pecten (Pecten) raymondi brionianus, N.Vare...........0. ccc eee teeteeeees 148 Pecten (Pecten) andersoni gonicostus, N.VAP........cccccccccccecceveeeseveevecesseeveeveeeeees 149 Modiolus gabbi subconvexus, NeVare.e.c.cceccccccccccecceeceveceeeeeeeeeeeeeeeeeeeeeteteteesevntees 149 Modiolus veronensis, D.S)..........0.c:cccc:cecccessesessesscssessesarsscsssessssseseessenssstessevsavessesvscens 150 Cyrena (Corbicula) diabloensis, n.spe.n.cccccccccccccccceccsecececetseeevseseseevateccstsetevetecseees 150 (anit TMMECOLDIS EV Ale ete sre ce eats ae eeetsa cee teacee ss sss s¢encysses-deveevey teases eseeeemeeceee 150 AVETMUIS HO TIOMTAI As TUES Pies eeiaccesec ce ceessceaeese oc snsesuessceueesoeseeeesetl scesiuptsatseyesssrvavesscutnesees 151 Pie] een CHE ATI ONES Dean gem metre ies aati ctesiasnesvaretssomancesetnntews Sabon ter ate 151 AMON AmWALLISIMDITT S]o 2 meneame Mate sense nc sedeneetccbvzsctessecae tc ccreen tot taraslsSetauieo see 152 SplsUlagalcavaubnomiamayine yale weacseesed ssc ssuet-dueasereeeevacyiees sseeevieee neces 152 @allnostoniay obliquistriatay Msp ..s.c..ses.sscesese sess cveesessesteseess-ccetevesecsutaeyeeevesess 153 SIMU (SI PAehUs) oT SSM ATIUI, MSPs. seesseese. ssesteteeseseecesca.teetsesseuesacsessstyeaszseseesse sees 153 ING@SSAmwihltMe vats p tere: saicecscstMecvan srcisivseisistatsgen tea scesicatescshsnupitssstisesiitegietien eee e 154 SSUONOM All AeO GLEOEMSISN TEST cceasecsseesesssusevsevsacescssevsstsssceseesicessoesacessnsacssssqseseeuseeeevay.. 155 Trophon daviesi, n.sp.......c.00e BE Ee ee RT are RE aca eee eee ao Trophon gracilis clarki, n.nom............ Be EE Per CPN REP SnD ear ESR ac ee See ee 156 PAG AINE ENTITY 8 TO CLE UI IMs STO 50s scsceseessecee-e-2.4steveeseecvecsecessleeeseeceeesucyeeses0ssseetuieususvatsosvuets 157 Koilopletra, mn. gen. .......cccccccccsccessesessesseseseeesseesceacsecsecsesevacsevsessesesateassevsesevavsavererens Alay Koilopleura sinuata, (Gabb).o....0c0ccccccccccccccecccsvseeseeevsevsvsseseveveevevvavsevseveveevatvevsevseeees 158 COSTE, STAs FEST Ss aS) eee ees eC er 159 Key to localities.........ccccccccccsscsessscscsecscsssesssvscsesnssssvsvssscsssvavsessessessevscssessearsvstsnsecaceees 159 134 University of California Publications in Geology [Vow 18 INTRODUCTION AND ACKNOWLEDGMENTS This paper presents the results of a study of the faunal and strati- graphic relations of the Briones formation to the adjacent formations in an effort to determine its position in the geologic scale. The results indicate: (1) that the Briones probably should be classified with the San Pablo group (Upper Miocene) rather than with the Monterey eroup (Lower and Middle Miocene); (2) that it is a minor eycle of deposition distinct from the Cierbo formation.* Hitherto in its relationship to other strata, the Briones formation has occupied a more or less uncertain position. The term Briones was first used by Professor A. C. Lawson? in 1914 in the San Francisco Foho. It was apphed to the ‘‘Scutella breweriana beds,’’ which at that time were regarded as forming the upper faunal member of the Monterey group in the region east of San Francisco Bay. Dr. J. C. Merriam® in 1898 was the first person to indicate the faunal distinct- ness of the ‘‘Seutella breweriana beds.’’ He included them, however, in the undifferentiated Miocene beneath the San Pablo. Very little detailed work has been done on the Briones since then. A few writers* have mentioned a faunal similarity between the Briones and the San Pablo, but they have included the Briones in the Monterey group. However, Clark® indicated that perhaps the Briones might have a closer relationship to the San Pablo than to the Monterey. 1 The recognition of the Briones as a part of the San Pablo group causes the ““Tower San Pablo’’ formation to become the middle member of the group. In order to overcome this ambiguity, Professor B. L. Clark, in his recent paper on the Marine Tertiary of the West Coast of the United States, in the Journal of Geology, volume 29, page 601 (1921), applies the name Cierbo formation to the ‘Tower San Pablo,’’ and he uses the term Santa Margarita for the Upper San Pablo. He retains the name San Pablo for the entire group consisting of the Briones, Cierbo, and Santa Margarita. In the present paper, unless otherwise stated, the term San Pablo refers to that part of the San Pablo group above the Briones, viz., the Lower San Pablo (Cierbo) and the Upper San Pablo (Santa Margarita). In other words it refers to the San Pablo group as understood previous to the application of the evidence here presented. 2 Lawson, A. C., San Francisco Folio, U. 8. G. S. No. 193, p. 11, 1914. 3 Merriam, J. C., Distribution of the Neocene sea-urchins of Middle Cali- fornia, Univ. Calif. Publ. Bull. Dept. Geol., vol. 2, p. 112, 1898. 4+ Merriam, J. C., A note on the fauna of the Lower Miocene of California, Univ. Calif. Publ. Bull. Dept. Geol., vol. 3, p. 378, 1904. Weaver, C. E., The stratigraphy and palaeontology of the San Pablo forma- tion of Middle California, Univ. Calif. Publ. Bull. Dept. Geol., vol. 5, p. 251, 1909. Clark, B. L., Fauna of the San Pablo group of Middle California, Univ. Calif. Publ. Bull. Dept. Geol., vol. 8, p. 436, 1915. 5 Loc cit., p. 436. 1922] Trask: The Briones Formation of Middle California 135 Most of the field work for the present paper was done during the summer of 1919, but several days were spent in the field in the fall of 1920 and the spring of 1921. The paleontological evidence is based both on collections made during this field study, and on previous col- lections made by the University of California. The writer is particularly indebted to Professor B. L. Clark, whose personal supervision, suggestions, and codperation, both in the field work and determination of fauna, have made possible the results here presented. Through the kindness of Professor James Perrin Smith, the writer has had access to the collections of the Briones at Leland Stanford Junior University. He is particularly indebted to Mr. Frederick P. Vickery of the Southern Branch of the University of California for much information concerning the nature of the southern extension of the Briones, and for assistance with the maps and paleontological col- lections of the Stanford Geological Survey. The work of determining the fauna has been greatly facilitated by the excellent collections made by Professors J. C. Merriam and B. L. Clark. Acknowledgment is also due Mr. E. L. Furlong of the Museum of Paleontology at the University of California for numerous suggestions and friendly criticisms. AREAL DISTRIBUTION OF BRIONES FORMATION The Briones formation is so far known only from a limited area near San Francisco Bay. It is particularly well developed in the western part of Contra Costa County, which has been the chief field of investigation. The most easterly known exposure of the Briones is on the south- west flank of Mt. Diablo. Mr. Vickery informs the writer that he has observed the Briones extending to a point a few miles south of Mt. Hamilton. Twenty-five miles to the west in the Santa Cruz Quad- rangle® and extending northerly along the San Francisco Peninsula, the Briones has not been reported as occurring between the Monterey and the Santa Margarita. Professor B. L. Clark has told me that he has observed the Briones as far north as Carneros Creek, just west of the city of Napa, some thirty-five miles north of San Francisco. 6 Branner, J. C., Arnold, Ralph, and Newsome, J. J., Santa Cruz Folio, U. S. G. S. No. 163, 1909. 136 University of California Publications in Geology [Vou.138 This limited known occurrence of the Briones deposits and the fact that in all other regions in California the Briones formation has not been recognized between the Monterey and the Santa Margarita, indicate that the Briones sea was probably an embayment of small extent. DESCRIPTION OF THE FORMATION The Briones formation shows a wide range in thickness. The minimum noted is on the south side of Mt. Diablo in the vicinity of Sycamore Creek, on the east side of the Walnut Creek synecline. Here the thickness is about 450 feet. Ten miles to the north along the strike the thickness of the formation has increased to over 1000 feet. Five miles to the west on the west side of this syncline, the thickness of the Briones averages about 1100 feet. On progressing northwesterly toward San Pablo Bay, the deposits gradually increase in thickness and attain a maximum of over 2300 feet. One of the most typical exposures of the Briones formation is found on the southwest side of Mt. Diablo. Here the basal beds consist of some 75 to 150 feet of gray, fairly well indurated, medium-grained, slightly fossiliferous sandstones. Overlying these sandstones are about 75 feet of hard, massive, firmly cemented, coarse-grained sandstones, which in places are finely conglomeratic. These beds contain a great number of fossils and the shells are packed so closely together that they make veritable shell beds. The strata overlying these shell beds vary in thickness from 300 to 800 feet and consist of yellow, sandy shales alternating with fine-grained sandstones. Certain members are relatively resistant to erosion and appear as small longitudinal ridges on the sides of the hills. Near the top of the formation the deposits become more fine-grained and shaly in texture. In the Contra Costa Hills and regions to the south, except in the territory near San Pablo Bay, the exposures of the Briones formation are very similar to those found on the southwest side of Mt. Diablo. The most striking features are the hard, massive, extremely fos- siliferous, reef-like sandstones near the base of the formation, which, due to their resistant nature and generally high angle of dip, weather in bold relief. In the northwestern portion of the Contra Costa Hills, progressing northward from Walnut Creek to San Pablo Bay, the Briones deposits gradually thicken, and become more fine-grained in texture. Even the 1922] Trask: The Briones Formation of Middle California 137 coarse-grained reef-like beds, so prominent in other sections, gradually merge into soft fine-grained sandstones. In the San Pablo Bay region, the Briones is composed of three lithologic members, two very similar sandstones and an intermediate shale. As a rule the sandstones are fine-grained, soft, yellow, more or less fossiliferous, and in places grade into sandy shales. The maximum thicknesses of the lower and upper sandstones are 1000 and 800 feet, respectively. The middle member, which is a shale, attains a maximum thickness of 600 feet near San Pablo Bay. Lawson’ has named it the Hercules shale member. It thins to the southwest, and six miles from the bay, it has a thickness of less than 200 feet. At this point the continuity of the section is broken by a fault, and the Hercules shale member has not been definitely recognized to the south. The Hercules shale is composed of a yellow, unfossiliferous, bitumi- nous shale, which, lithologically, appears similar to the shales of the Monterey group below. As yet no differences in dip and strike have been noted between the Briones and the formations above and below. There is, however, a rather sharp change in lithology between it and the adjacent for- mations. As a general rule the upper part of the Monterey consists of a yellow shale (though in a few localities it is composed of a soft, yellow, fine-grained sandstone), while the base of the Briones is char- acterized by a gray, coarse-grained sandstone. The upper part of the Briones is usually composed of a soft, yellow, fine-grained sand- stone or sandy shale, while the base of the San Pablo consists of a hard, gray, coarse-grained to finely conglomeratic sandstone. On the southwest side of Mt. Diablo in Wall Point Cafion there is an irregular contact and a sharp change in lithology between the Monterey and the Briones. The upper Monterey is composed of a yellow shale, while the base of the Briones consists of a hard, gray, coarse-grained sandstone. Astrodapsis brewerianus (Rémond) has been found in the sandstone five centimeters above the contact, thus indicating the identity of these beds with the Briones. The contact is quite distinet and somewhat irregular. Erosional gutters, ten to fifteen centimeters in depth, are observed in the upper part of the Monterey shales. Cracks in the Monterey, a foot or more in depth, are found filled with the sandstone matrix from above. A layer of isolated pebbles, about two centimeters in diameter, occurs just above 7 Lawson, A. C., San Francisco Folio, U. 8. G. S. No. 198, p. 11, 1914. 138 University of California Publications in Geology [Vou. 13 the contact. There is no evidence of differences in dip and strike, as none of the beds of the Monterey appears to be truncated by the Briones. The lithologic change, irregular erosion line, isolated layer of pebbles above the contact, and the finding of Astrodapsis brewer- tanus (Réemond) just above the contact indicate that this is probably the contact between the Briones and the Monterey. Similar irregular contacts have been found between the Monterey and the Briones in two other localities. One of these is on the northern end of Shell Ridge, some seven miles northwest along the strike of the contact mentioned above. The other is located in the northern part of the Concord Quadrangle, in a Santa Fé Railroad cut, one mile east of Muir Station, on the north end of the Pacheco syncline. In each of these two localities there is a sharp lithologie change, irregular contact line, and in the one on the north end of the Pacheco syncline, shale pebbles, three to five centimeters in diameter, very similar to the underlying Monterey shale, are found in the sandstone above the contact. Pholas borings are also found just beneath the contact. This contact is somewhat more irregular than the others—erosional gutters nearly a foot in depth being present. On the southwest side of Mt. Diablo on the northern side of Syea- more Creek, there is an irregular contact between the Briones and the Lower San Pablo (Cierbo). Here a road cuts across the contact three times, and the break may be traced interruptedly for about one-half mile. There is a sharp change in lthology. The beds below the contact usually are composed of yellow, sandy shales, containing Nassa whitneyi, n.sp. The beds above the contact consist of hard, massive, finely conglomeratic sandstones. Numerous borings of the Pholadid type are found in the beds immediately below the contact. Cracks a foot or more in depth are found in the shale below, filled with the sandstone matrix from above. There is no appreciable difference in dip and strike. The sharp change in lithology, uneven contact, presence of Pholadid borings, and Nassa whitney, n.sp., found just below the contact, point to this being the line of demarcation between the Briones and the San Pablo. Clark* has described another disconformity between the Briones and the San Pablo, which occurs about two miles to the north in Wall Point Canon. This is very similar to the one mentioned above. There is a sharp change in lithology, irregular contact line, and borings of the Pholadid type are found in the beds just beneath the contact. 8 Clark, B. L., Fauna of the San Pablo group of Middle California, Univ. Calif. Publ. Bull. Dep. Geol., vol. 8, p. 408, 1915. 1922] Trask: The Briones Formation of Middle Califorma 139 FAUNA The Briones formation is here treated as a unit. Sufficient collee- tions have not been made to warrant the determination of minor faunal zones, if any occur. There are several forms which are regarded as characteristic of the Briones formation. The most characteristic is Astrodapsis brewertanus (Rémond), which is quite common. In fact, for several years previous to the application of the name Briones, the term ‘*Seutella breweriana zone’’ was applied to these beds. Other good markers are: Astrodapsis brewerianus diabloensis Kew Pecten ricei, n. sp. Koilopleura sinuata (Gabb) Trophon daviesi, n. sp. Modiolus gabbi subconvexus, n. var. Modiolus veronensis, n. sp. The following species complete the list of those forms so far recog- nized only from the Briones. a, a, a> a> a> a> a4 x x x x ® Macoma andersoni Clark as yet has not been found in the Briones in other regions, but it is fairly common in the Upper San Pablo (Santa Margarita). 10 Nassa whitney, n.sp., may possibly oceur in the Monterey. 142 PrLEcy PopA— (Continued) CoMPLETE LIST OF KNOWN SPECIES FROM THE BRIONES FORMATION WITH THEIR GEOLOGIC RANGE— (Continued) Oligocene Monterey group Macomaandensomis Clarke errs scsccee.ce sess eee eee Macomta masta, (Conrad) i 22eccescs-ccecsseeesesesetone ese x? x Macomay ct: secta (Conrad)! 22. poco oeeet na x Macoma ef. yoldiformis Carpenter ................-.-. Marcia oregonensis (Conrad) ........-.--.-------------+ x x Miletus? ailibeu iC ommetch) seece occas eceseeeres ce eeeeeewee Modiolus ef. capax Conrad .............. Se eee ae Modiolus gabbi subconvexus, n. sp. .....-.......-.--- Modi olisT venONeNSIs, Say cses-cceceaneerereressereeesants Mulinia cf. densata Conrad .............--.-------------+ Mnmlinian allo ensiss Palchcar diesccccses e-em es Lee Miva oveults 9 ((@ Omir a Ch) ersseeeces seeeerenees, ceases seeseceee es Seees OES Mytilus ef. perrini Clark Mytilus ef. trampasensis Clark ......2.2..22------------ Ostrea bourgeoisi Réemond =. 2s. DEFOR Lop oe ts) 0 Wee er ee Ee ean Panope generosa Gould —...02..22..22.ceeceeeeeeeeeeeeeeeees ae x Pecten andersoni gonicostus, n. var. ae ecten pilameatusm@ law kee :creeseccseeteene se eee Peeten crassicardo (Conrad) ..........-.2...-.000------- Pe cbenmr rary om cis ©] eine gore ee ceceeoceree ec oeenener ee Pecten raymondi brionianus, n. var, -.........--...- iP GGT OTM LC Ole ris S10 sgeee ere ee tees ee eee ee Pecten tolmani Hall and Ambrose ..................-- PB OGUENe Vick Grsyaly, WseS nmeccsseaee tenses saceenne ames ores Phacoides annulatus (Reeve) .......0000....2002...---- ARAN GATE SY eyes cease ee eee cea cee teee ee eae scans eee aaa sna Wee: Saxidomus nuttalla Conrad 22 _— x Schizothaerus nuttallii (Conrad) ................-...-- Muligua lcidar (Comma) ec cceecceeccsceceset sess eeseeeeces ae pees Sfolesat, joyeyenabaut Ollbn de See or x? MOLEM MSL aren Si Cr OU peers ene eres meee ere Spisula ‘allbaria \(Comrad) 2.2 ceteecsseectecceeeee roses aS x Spisula catilliformis Conrad ...........22.-2..------------ a x Spisula faleata brioniana, n. var. ........ Tellina oregonensis Conrad Tivela diabloensis Clark .......0......20-.0-:ccseee-cecee0 ees May elias rmeeped a vrai TS py ese Viens DriOMiamias aT Sy) sea sere eee aee eee eee ee sViemuSpamaurbm dC ae i eee ces eee eee ceeereeeanes pre Yoldia cooperi Gabb - : SVOLGR ES SPs occ cees eo oe sea aes ee Se Hfalaryo) ve Ketek colenat ey et2), (Gi) 0) 6) tes rege eee eer rige «tots GASTROPODA DXF NCL 0) 0s) 0 ee PP ee eee ER EE St Aicam thin ai OLLI, Ws Sys secs eccescceesccrrtee ee eese = ze x DOR IN GPR ON LP PS ee PM mS IG Pee OG, OR Re PR PR Ge GN CO OK: I OC PS SC x Ox oe oe Briones University of California Publications in Geology x x x xX x x x San Pablo x x xX KX KX XK XK x xX XK &X x xX xX KX XK XK XK [ Vou. 13 Etchegoin x x XxX xX 22] Trask: The Briones Formation of Middle California 143 CoMPLETE LIST OF KNOWN SPECIES FROM THE BRIONES THEIR GEOLOGIC RANGE— (Concluded) 11 Acanthina perrini, n. sp., is omitted from the summary which are questionably correlated with the Briones. FORMATION WITH GastTropopa— (Continued) 6 35 a & & & IN ibheas 1eey ra cavoyaueht (Ollehelie aye ye eee Be x Calliostoma obliquistriata, n. sp. -.....-2.22.-22-2-- Calyptraea filosa (Gabb) .........2.222..2::2::220000000e m x Cancellaria ef. condoni Anderson ..................---- ae x x Cancellaria pabloensis Clark -......2-------:1--1---+ x x Canecellaria ef. wynoothchensis Weaver .......... — x x CG CSF irE ol sb 00a) 6 eee eee eee are er x Chrysodomus ef. cierboensis Clark ...............-.--- x x Chrysodomus imperialis Dall ................22--22---2---- x Crepidula praerupta Conrad ............22---.---------!- tee x x Ficus rodeoensis English ...............----.-se--c-000+ x Ficus stanfordensis Arnold ................22..22.:2----- x x Fissurella, sp. - x JPNUISHHOTDS,, (S)D. coccenoncossocrrnpacrccoccrocctnnrieccoore aarti x Koilopleura sinuata (Gabb) ......-...2...2..--22:--0+--- x INGEVSISER ay'glalah rae (aly 00g, (5) 0), eee eee eee ues x? x INiaticamenmolctan Clee eeeesesseseesenceesse sae eseereseesss x x INaiti@an karkienisigy ©] areata cseesnseseseen nesses eee x x INJevnncekay, jor enlWoyevatsnis) (Ollewele eee eee es eee x x COM ay tehhaaQo yo lSpiy 0k tS Oh eee eee eee Pere x Olivella ef. pedroana (Conrad)...............2-.-2------ Te x x x x RUMI PHIM EMATINIIMN, Me SP). seeceyscceee teste ecsee--eeeeeree se x Siphonalia rodeoensis, n.sp. - x Thais ef. lima Martyn Xx x x Mop hon dawaesihy Weis) aes se eee eee ee ae x Trophon gracilis clarki, n.nom, ...............-..------ x x MUTT S AST) ae hoes esec nsec cece sce eseue ses Sueetueesee se. Setsecsevee x MUGS SSP i Or oes Sse acest et x SCAPHOPODA Meribel Ss ee ce eee eee eee ees x ELASMOBRANCIIII Spine and teeth Baie eeceew. ee x STATISTICAL SUMMARY OF FAUNAL LIST Species IBYCI UNO YCN SEINE eer eee ee eee ees eee eee ee 3 NS Tayi OZ. 0 Bg ee ree SO eae J PelecypOd a. 20s aoe te Se err eee 56° LG EUS a0 OK OX 6 ls pore re eres a eo eee eee ee een") SHEN] OA 0 OY 6 Wal ace ore Aa ae ] ANT OE G) OY 06 Fe lee Re Ne ae eee ee 3 TDA SSab\ 0) Ones she ree er ere eer eee oe ee 1 Total number of species ...........-2------:---eeeceeeeees 94. as it is found in beds 144 University of California Publications in Geology [Vou.18 INumiber, of determinable "species 22iccrcccceccecrececeteszessereecee eee ss tee ees ee 6412 Number of species so far recognized only in the Briones........ ... 21 or 32.8 % Number of species that extend into the San Pablo .................-.- .... 41 or 64.0% Number of species that extend into the Etchegoin (Pliocene).......... 19 or 29.7% Number of Recent species occurring in the Briones .....................---.--- 12 or 18.8% Number of species that extend into the Monterey group (Vaqueros amid Temb LOT) eacecceacseeva cee cee nereree reese Deedee s ovee secu catieas ee 12 or 18.8% Number of species that extend into the Oligocene .........-----------.---=- 2or 3.1% Number of species peculiar to the Briones and San Pablo .................. 20 or 31.2% Number of species peculiar to the Briones and the Monterey group lor 1.5% RELATION OF THE BRIONES FAUNA TO THE MONTEREY FAUNA A study of the known fauna of the Briones formation indicates that it has a much closer relationship to the San Pablo than to the Monterey. Twelve out of the sixty-four determinable species (18.8 per cent) extend into the Monterey, while forty-one species or 64 per cent occur in the San Pablo. Of the twelve species that extend into the Monterey, ten are known to occur in the San Pablo, one (Tellina oregonensis Conrad) occurs in the Oligocene, and only one (Chione panzana Anderson and Martin)’* is peculiar to the Briones and the Monterey. Since only one (or possibly two) species out of a deter- minable fauna of sixty-four species is peculiar to these two formations, it appears that the Briones fauna is distinct from that of the Monterey. RELATION OF THE BRIONES FAUNA TO THE SAN PABLO FAUNA Of the forty-three known Briones species that extend into other formations forty-one occur in the San Pablo. Of these, twenty are peculiar to the Briones and to the San Pablo. They are: Dosinia arnoldi Clark Tivela diabloensis Clark Dosinia merriami Clark Venus martini Clark Dosinia merriami occidentalis Clark Zirphaea dentata Gabb Macoma andersoni Clark Astralium raymondi Clark Mulinia pabloensis Packard Caneellaria pabloensis Clark Ostrea bourgeoisi Rémond Ficus stanfordensis Arnold Pecten bilineatus Clark Natica arnoldi Clark Pecten ecrassicardo (Conrad) Natica kirkensis Clark Pecten raymondi Clark Natica pabloensis Clark Pecten raymondi brionianus n. var. Trophon gracilis clarki, nov. nom. 12 The large number of indeterminable species is chiefly due to the generally poor preservation. A rather high percentage of the Briones fossils consists of casts or molds. 13 Nassa whitneyl, n.sp., may possibly extend into the Monterey, but even if it did, there would then be only two species peculiar to these two formations. 1922] Trask: The Briones Formation of Middle California 145 A large number of the species peculiar to the Briones and the San Pablo are highly ornamented forms, or are of types which do not have long ranges, and which, if the Briones were a distinct period, probably would not extend into the San Pablo, such as the following: Astralium raymondi Clark Cancellaria pabloensis Clark Trophon gracilis elarki, n. nom. Pecten raymondi Clark Pecten raymondi brionianus, n. var. Pecten bilineatus Clark Ficus stanfordensis Arnold In addition to these highly ornamented types, some forms are relatively common in the Briones which as yet have not been found in the San Pablo, but which are very closely related to some San Pablo species. These are: BrIONES ForM San PasBio HoMOLOGUE Astrodapsis brewerianus diablo- ensis Kew Modiolus gabbi subconvexus, n. var. Trophon daviesi, n. sp. { Astrodapsis cierboensis Kew Astrodapsis tumidus Rémond Modiolus gabbi Clark Trophon ponderosum Gabb The general character or facies of the fauna of the Briones and the San Pablo appears to be very similar. A large number of species are numerically quite abundant in both formations: Saxidomus nuttalli Conrad Schizothaerus nuttallii (Conrad) Siliqua lucida (Conrad) Solen perrini Clark Solen sicarius Gould Spisula albaria (Conrad) Spisula catilliformis Conrad Calyptraea filosa (Gabb) Crepidula praerupta Conrad Natiea kirkensis Clark Natica pabloensis Clark Area trilineata Conrad Diplodonta parilis (Conrad) Dosinia arnoldi Clark Dosinia merriami Clark Dosinia merriami occidentalis Clark Metis alta Conrad Mulinia pabloensis Packard Mya ovalis (Conrad) Ostrea bourgeoisi Rémond Pecten raymondi brionianus n. var. (San Pablo homologue, P. ray- mondi Clark) The above fossils are very common and constitute numerically over one-half of the specimens found in the Briones, yet they are also quite abundant in the San Pablo. The lthologie sequence of the Briones and the San Pablo is very similar. Both possess massive, hard, fossiliferous sandstones near the base of the formation. The upper parts of both consist of alternating fine-grained sandstones and sandy shales. As yet, no differences in dip and strike have been observed between the Briones and the San Pablo. Hence from the faunal similarity to the San Pablo, and the faunal distinctness from the Monterey, it is concluded that the Briones 146 University of California Publications in Geology [Vou. 138 formation should be included in the San Pablo group rather than in the Monterey, or in a distinct group of its own. That the Briones is a distinct formation from the Lower San Pablo (Cierbo) has already been shown by Merriam‘ on the basis of the sea-urchins. The Briones form, Astrodapsis brewerianus (Rémond) has not been found in the Lower San Pablo, and the Lower San Pablo form, Scutella gabbi (Rémond) has not been observed in the Briones. The Briones has twenty-one species that have not been found in other formations; the Lower San Pablo has twenty-one species that are peculiar to it; and there are only five species which are restricted to these two formations. This indicates a faunal distinctness. The following are the twenty-one species pecuhar to the Briones: Astrodapsis brewerianus (Rémond) Astrodapsis brewerianus diablo- ensis Kew Antigona willisi, n. sp. Leda furlongi, n. sp. Modiolus gabbi subeonvexus n. var. Modiolus veronensis, n. sp. Pecten andersoni gonicostus, n. var. Pecten ricei, n. sp. Pecten tolmani Hall and Ambrose Pecten vickeryi, n. sp. Spisula falcata brioniana, n. var. Tivela merriami, n. sp. Venus brioniana, n. sp. Calliostoma obliquistriata, n. sp. Ficus rodeoensis English Koilopleura sinuata (Gabb) Nassa whitneyi, n. sp. Oliva simondsi, n. sp. Sinum trigenarium, n. sp. Siphonalia rodeoensis, n. sp. Trophon daviesi, n. sp. The following are the twenty-one species pecular to the Lower San Pablo (Cierbo) : Asterias rémondii Gabb Scutella pabloensis Kew Pecten cierboensis Clark Pecten crassiradiatus Clark Pecten weaveri Clark Pitaria behri Clark Pitaria stalderi Clark Sanguinolaria alata (Gabb) Spisula abscissa (Gabb) Tivela diabloensis angulatum Clark Bursa carinata Clark Calyptraea diabloensis Clark Cerithiopsis turneri Clark Chrysodomus cierboensis Clark Chrysodomus pabloensis Clark Columbella pittsburgensis Clark Hemifusus dalli Clark Littorina rémondii Gabb Murex (Ocinebra) selbyensis Clark Thais cierboensis Clark Trophon dickersoni Clark The following are the five species peculiar to the Briones and the Lower San Pablo: Dosinia merriami Clark Ostrea bourgeoisi Rémond Tivela diabloensis Clark Trophon gracilis clarki, n. nom. Natica kirkensis Clark 14 Merriam, J. C., Distribution of the Neocene sea-urchins of Middle Cali- fornia, Univ. Calif. Publ. Bull. Dept. Geol., vol. 2, p. 117, 1898. 15 Clark, B. L., Fauna of the San Pablo group of Middle California, Univ. Calif. Publ. Bull. Dept. Geol., vol. 8, pp. 417-423, 1915. 1922] Trask: The Briones Formation of Middle California 147 The geographic distribution of the Briones formation appears to be somewhat different from that of the Lower San Pablo, for on the north side of Mt. Diablo the Lower San Pablo is present, while the Briones is absent. Hence from (1) the faunal distinctness of the two formations, (2) the different geographic distribution, and (3) the lithologiec difference with erosion contacts, it is concluded that the Briones is a minor cycle of deposition distinct from the Lower San Pablo: The San Pablo group would accordingly consist of three minor epochs, Briones, Lower San Pablo (Cierbo), and Upper San Pablo (Santa Margarita). DESCRIPTION OF SPECIES Subkingdom MOLLUSCA Class PELECYPODA. Family Lepipar Genus LEDA Schumacher LEDA FURLONGI, n. sp. Plate 1, figures la and 1b Type.—No. 12362;.cotype—No. 12363, Univ. Calif. Mus. Pal. Shell small, subovate, moderately ventricose; beaks obscure, nearly central; slightly opisthogyrous; posterior dorsal edge gently concave; anterior dorsal edge nearly straight; anterior end regularly rounded; posterior end subacutely rostrate; lunule and escutcheon elongate, lanceolate, extending almost the entire length of the dorsal margins, and rather strongly pouting; surface sculptured with numerous fine regular concentric lines; hinge plate unknown. Dimensions.—Type specimen U. C. no, 12362; length, 20.8 mm.; alt., 11.3 mm.; thickness of both valves, 8 mm. Cotype, U. C. no. 12363, length 16.1 mm.; alt., 8.6 mm. Occurrence.—Briones formation, U. C. loc. 15. Named in honor of My. E. L. Furlong of the Museum of Paleontology, Uni- versity of California. L. furlongi, n. sp., somewhat resembles L. taphria Dall,’® but differs from the latter in being narrower, more elongate posteriorly, possessing finer concentric sculpturing, and the lunule and escutcheon being more strongly pouting. It differs from LD. ochsnert Anderson and Martin" in being less acutely elongated posteriorly, the posterior dorsal slope being less concave, and the concentric ribs being finer. 16 Dall, Nat. Hist. Soe. Brit. Columbia, Bull. no. 2, p. 7, pl. I, figs. 6-8, 1897. 17 Anderson and Martin, Cal. Acad. Sci., ser. 4, vol. 4, p. 53, figs. 8a, 8b, 8c, 1914. 148 University of California Publications in Geology [Vou. 18 It differs from DL. whitmani Dall’* in that it possesses finer and more evenly distributed ribs over the entire surface, the posterior dorsal edge is less concave, and the shell appears much narrower. Family PECTINIDAE Genus PECTEN Miller PECTEN (LYROPECTEN) RICEI, n. sp. Plate 2, figures 1 and 2 Type.—No. 12364; cotype—No. 12365, Univ. Calif. Mus. Pal. Shell medium in size; about as long as high, equilateral; apical angle about 89°; anterior and posterior dorsal margins strongly depressed; surface of left valve with fourteen low flat topped to broadly rounded ribs; interspaces flat, about equal in width to ribs, and possessing from three to four, almost invariably three, small riblets, which have a tendency to become bifurcated near the ventral margin. Dimensions.—Type specimen U. C. no. 12364; alt., 63.7 53 mm.; apical angle, 89°. Cotype, U. C. no. 12365; alt., 7 mm.; apical angle, 93°. Occurrence.—Briones formation. Type from U. C. loe. 3535; cotype from loc. 85384. Named in honor of Professor C. D. Rice, University of Texas. mm.; width, about 3 2.3 mm.; width, 70.7 a PECTEN (LYROPECTEN) VICKERYI, n.sp. Plate 4, figure 1 Type in Stanford University Paleontological Collection. Shell large, slightly more wide than high; ears about one-half the width of the shell; dorsal margins strongly depressed and quite long, being about three- fourths the height of the shell; surface with sixteen prominent ribs; every third rib being higher and more strongly developed than the others; interspaces about as wide as ribs; both ribs and interspaces ornamented with numerous fine riblets; ears with five to six small ribs. Dimensions.—Alt., 99 mm.; width about 106 mm.; apical angle, 100°. Occurrence—Briones formation, vicinity of McGuire Peaks, Pleasanton Quadrangle. Note.—Only one valve has been found. Type specimen possesses depression near ventral margin. Named in honor of Mr. Frederick P. Vickery, Department of Geology, South- ern Branch, University of California. PECTEN (PECTEN) RAYMONDI BRIONIANUS, n. var. Plate 1, figures 2 and 3 Type.—No. 12368; cotype—No. 12369, Univ. Calif. Mus. Pal. Dimensions.—Type specimen U. C. no. 12368; alt., 37.3 mm.; width, 37.3 mm.; length of ears, 18.7 mm.; apical angle, 100°. Cotype, U. C. no. 12369; alt., 31.7 mm.; width, 32.7 mm.; apical angle, 100°. Occurrence.—San Pablo group. Type and cotype from U. C. loc. no. 3532. 18 Dall, U. 8. G. S. Prof. Paper 59, p. 103, pl. XIV, fig. 4, 1909. 1922] Trask: The Briones Formation of Middle Califorma 149 An analysis of over one hundred specimens of the forms of Pecten raymondi Clark found in the Briones and the San Pablo formations shows that there are two end varieties with a gradual gradation between. The San Pablo forms, as a general rule, possess a relatively more convex left valve, and higher and stronger ribs which are relatively close together. This is the typical P. raymondi described by Clark.'” The forms found in the Briones have only slightly convex valves, and the ribs are relatively low and widely separated. The name P. ray- mondi brionanus is suggested for this variety. PECTEN (PECTEN) ANDERSONI GONICOSTUS, n. var. Plate 1, figure 5 Type.—No. 12370, Univ. Calif. Mus. Pal. Shell small to medium in size, subcireular, nearly equilateral; dorsal margins gently coneave; anterior dorsal margin Jonger than posterior; ventral margins strongly arcuate; right valve gently convex, and possesses about seventeen sub- angular ‘‘V’’ shaped ribs; interspaces wider than ribs; hinge line about three- fifths width of shell; ears about equal in length; anterior ear with five ribs; posterior ear with four fine subangulate ridges, with interspaces wider than the ridges; byssal notch prominent. Dimensions.—Type specimen U. C. no. 12370; alt., 29.7 mm.; width, 30.2 mm.; length of ears, 18 mm.; apical angle, 100°. Occurrence.—Briones formation, U. C. loe. no. 1176. This species resembles P. anderson Arnold,?° but it differs from the latter in that the right valve is less convex, the ribs are less promi- nent, the interspaces are wider, and the ears are shorter and broader Family Myviuipar Genus MODIOLUS Lamarck MODIOLUS GABBI SUBCONVEXUS, n. var. Plate 3, figure 2 Type.—No. 12372, Univ. Calif. Mus. Pal. Shell very similar to M. gabbi Clark,21 but differs from the latter in that the umbonal ridge is less prominent; the shell is more convex, narrow, and tumid; the striations are slightly narrower and less prominent; and on the posterior slope the striations become much finer, closer together and more numerous. Dimensions.—Type specimen U. C. no. 12372; alt., 56.8 mm.; greatest width, 20.6 mm. Occurrence.—This is a common species in the Briones formation. Type from U. C. loc. no. 7938. 19 Clark, B. L., Univ. Calif. Publ. Bull. Dept. Geol., vol. 8, p. 450, pl. 46, figs. 1 and 2, pl. 47, figs. 1 and 2, 1915. 20 Arnold, U. 8. G. S. Prof. Paper 47, p. 82, pl. XXIV, figs. 5-8, 1906. 21 Clark, Univ. Calif. Publ. Bull. Dept. Geol., vol. 8, p. 458, pl. 48, fig. 1, 1915. 150 University of California Publications in Geology [Vou. 138 MODIOLUS VERONENSIS, n. sp. Plate 3, figure 4 Type.—No. 12378, Univ. Calif. Mus. Pal. Shell small to medium in size, flat and elongate; anterior end extending only slightly beyond beak; posterior dorsal edge straight and not separated from the posterior end by any well defined angle; anterior dorsal edge slightly concave; base evenly rounded; surface smooth, except for concentric lines of growth. Dimensions.—T ype specimen U. C. no. 12878; length, 40.6 mm.; greatest width, 17.9 mm. Occurrence.—Briones formation. Type specimen from U. C. loc. no. 3529. Family CyYRENIDAE Genus CYRENA Lamarck CYRENA (CORBICULA) DIABLOENSIS, n. sp. Plate 3, figures 5a and 5b Type.—No. 12374, Univ. Calif. Mus. Pal. Shell medium in size, subcircular; beaks anterior to the middle of the shell, inconspicuous, and only slightly prosogyrous; dorsal margins straight and nearly equal; surface smooth except for fairly heavy, irregular lines of growth; hinge plate heavy; posterior cardinal not as heavy as two anterior cardinals; nymph plate fairly long for this genus, but not as wide or as prominent as is often the case with Cyrena. Dimensions.—Type specimen U. C. no. 12374; alt., 37.6 mm.; width, 42.4 mm. Occurrence.—Upper San Pablo formation, U. C. loc. no. 1949. 9° This species differs from C. californica Gabb,?? found in the same horizon, in being more cireular in outline, in having less conspicuous beaks, which are less prosogvrous, in having heavier teeth and more obsolete laterals, and in possessing a less prominent nymph plate. Family CarpDmpAE Genus CARDIUM Linné CARDIUM CORBIS, n. var.? Plate 5, figure 3 Specimen.—No. 12376, Univ. Calif. Mus. Pal. Shell is very similar to Cardiwm corbis (Martyn),23 but differs in having on the average three or four less ribs. The Briones form has 29 to 30 ribs, while the recent form (the typical C. corbis) has 33 to 34. The preservation on all the specimens found in the Briones as yet is very poor, and it is difficult to tell whether this is a new variety of C. corbis or not. However, the twenty-nine ribs appear to be quite constant on the seven specimens at hand. Dimensions.—Specimen figured is U. C. no. 12376; alt., 34 mm.; width, 40 mm. Occurrence.—Briones formation. Specimen figured from U. C. loc. no. 207. 22 Gabb, Calif. State Geol. Surv., Palaeontology of California, vol. 2, p. 26, fig. 45, 1869. 23 Martyn, Univ. Conch., pl. XXVIII, fig. 2, 1784. 1922] Trask: The Briones Formation of Middle California 151 Family VENERIDAE Genus VENUS Linné VENUS BRIONIANA, n. sp. Plate 5, figure 1 Type.—No. 12377, Univ. Calif. Mus. Pal. Shell large, subcireular in outline, inequilateral, height about equal to width; anterior dorsal edge short, concave; posterior dorsal edge long and very gently convex; ventral margin strongly arcuate; surface of shell ornamented with numerous concentric undulations, on and between which are smaller incremental lines; hinge plate unknown. Dimensions.—Type specimen U. C. no. 12377; alt., 88.5 mm.; width, 86. 5 mm. Occurrence.—Briones formation, U. C. loc. no. 177. This species resembles V. conradiana Anderson,** found in the Temblor formation (Monterey group) in the southern part of the state, but it differs from the latter in that it is more symmetrical in shape, less produced posteriorly, and it possesses a fuller anterior ventral margin. Genus TIVELA Link TIVELA MERRIAMTI, n. sp. Plate 6, figures la and 1b Type.—No. 12378, Univ. Calif. Mus. Pal. Shell medium in size, height almost equal to width, ventricose, line of greatest ventricosity anterior to middle of shell; surface with slight depression posterior to middle; beaks prominent, only slightly prosogyrous, and a little posterior to middle of shell; dorsal margins straight, subacutely depressed, with greatest depression near beaks; posterior dorsal margin longer than anterior and with a slight depression, which is coexistent with the depression posterior to the middle of the shell; ventral margin strongly arcuate anteriorly; surface smooth except for fine incremental lines; hinge plate heavy; right valve with three cardinals; anterior cardinal nearly obsolete and very close to the dorsal margin; middle and posterior cardinals about equal in size, the posterior being somewhat the longer; nymph plate heavy and longer than any of the cardinals; anterior clasper long, with inner crest considerably below the level of the dorsal margin. The species is quite distinct because of its ventricosity, rounded dorsal margins, and peculiar hinge. Dimensions.—Type specimen U. C. no. 12378; alt., 62.3 mm.; width, 66.8 mm. Occurrence.—Briones formation, U. C. loe. no. 3582. Known only by right valve. Named in honor of Dr. J. C. Merriam. 24 Anderson, Proc. Cal. Acad, Sci., ser. 8, vol. 2, p. 195, pl. XTV, 1905. 152 University of California Publications in Geology [Vou. 18 Genus ANTIGONA Schumacher ANTIGONA WILLISI, n. sp. Plate 5, figures 2a and 2b Type.—No. 12379, Univ. Calif. Mus. Pal. : Shell elongate, subovate; lunule large, well defined, and depressed; escutcheon elongate, depressed, and well developed in left valve and apparently absent in right; anterior dorsal margin gently concave and about three-fifths the length of the posterior, which is almost straight; posterior end subacutely rounded; anterior end produced and broadly rounded; surface of shell sculptured by regular undulations; near the beak and over a large part of the surface, undula- tions about equal in size to interspaces, but near ventral margin become much more closely crowded; undulations and interspaces marked with fine incremental lines; hinge unknown. The species is quite distinct because of its elongate form. Dimensions.—Type specimen U. C. no. 12379; alt., 33.3 mm.; width, 42.7 mm.; greatest diameter, 22.8 mm. Occurrence.—Briones formation, U. C. loe. no. 146. Named in honor of Professor Bailey Willis, Stanford University. Family Mactripar Genus SPISULA Gray SPISULA FALCATA BRIONIANA, n. var. Plate 4, figures 2a and 2b Type.—No. 12380, Univ. Calif. Mus. Pal. Shell small to medium in size, subtrigonal, inequilateral, equivalve; beaks rather inconspicuous, incurved and only slightly prosogyrous; anterior dorsal edge long and straight; posterior dorsal edge straight to gently convex, and about two-thirds the length of the anterior dorsal edge; posterior end evenly rounded; anterior ventral end produced and subacutely rounded; surface smooth except for fine incremental lines; hinge plate short, resilifer shallow; cardinals small and fragile; laterals very short and close to laminae. Dimensions.—Type specimen U. C, no. 12380; alt., 17.6 mm.; length, 24.0 mm. Occurrence.—Briones formation. Type from U. C. loe. no. 3522. This variety resembles S. falcata (Gould),*° a recent species of the West Coast, but it differs from the latter in that it is higher in pro- portion to length; it possesses a more prominent umbonal ridge; it has a shorter hinge plate and shorter laterals; and the distance from the center of the hinge plate to the distal ends of the laterals is about one-half of what it is in S. falcata. 25 Gould, Proce. Brit. Soc. Nat. Hist., vol. III, p. 216, 1850. 1922] Trask: The Briones Formation of Middle California 153 Class GASTROPODA Family TROcCHIDAE Genus CALLIOSTOMA Swainson CALLIOSTOMA OBLIQUISTRIATA, n. sp. Plate 7, figures la and 1b Type.—No. 12385, Univ. Calif. Mus. Pal. Shell small, subconical; apex low; body whorl more than half height of shell; sutures depressed; sides of whorls convex; body whorl with about ten oblique ribs which are rounded and somewhat indistinctly nodose; ribs inclined at an angle of about 30° to the revolving lines; between base and the oblique nodes are two spiral ribs, the upper of which is the more prominent; lower spiral rib almost at base of whorl; surface also sculptured with numerous fine oblique riblets, inclined at an angle of 45° to the whorls; these are more pronounced between upper spiral rib and suture; base of body whorl flat, at right angles to the sides, and is ornamented with three revolving ribs; aperture not preserved. Dimensions.—Type specimen U. C. no. 12385; alt., 6.6 mm.; greatest width, 10.2 mm. i Occurrence.—Briones formation, U. C. loe. no. 3575. This species resembles C. bicarinatum Clark,”° occurring in the Upper San Pablo, but it differs from the latter in that it possesses the prominent oblique striations on the sides of the whorls, a lower spire, less prominent nodes upon the upper part of the whorls, and it has three instead of four revolving ribs upon the base of the body whorl. Family NATICIDAE Genus SINUM Bolten SINUM (SIGARETUS) TRIGENARIUM, n. sp. Plate 7, figures 2a and 2b Type.—No. 12386, Univ. Calif. Mus. Pal. Shell medium in size; spire low; number of whorls to spire three; body whorl large and seulptured with about thirty revolving ribs, about one to the millimeter; aperture subovate, elongate posteriorly. Dimensions.—Type specimen U. C. no. 12386; alt., 33.5 mm.; greatest width, 35.38 mm.; alt. of aperture, 29 mm.; maximum width of aperture, 17.8 mm. Occurrence.—Briones formation, U. C. loc. no. 3576. This species is similar to S. scopulosum (Conrad) ,27 but it differs from the latter in that it possesses thirty spiral ribs on the body whorl, 26 Clark, Univ. Calif. Publ. Bull. Dept. Geol., vol. 8, p. 481, pl. 65, figs. 14 and iy, als nis, ; 27 Conrad, U. 8. Expl. Exp. Geol., Appendix, p. 727, pl. 19, figs. 6 and 6a, 1849. 154 Unversity of California Publications in Geology [Vow 138 while S. scopulosum has forty-five. In comparing the number of ribs per 5 mm. on specimens of S. trigenarium, n.sp., and S. scopulosum of about the same size, five ribs per 5 mm. are found in the former and eight ribs per 5 mm. are found in the latter. Also the aperture of S. trigenarium is more elongate posteriorly. Family NAssIDAE Genus NASSA Lamarck NASSA WHITNEYI, n. sp. Plate 7, figures 3 and 6 Type.—No. 12387; cotype—No. 12388, Univ. Calif. Mus. Pal. Shell medium sized; apical angle averages 53°; number of whorls to spire five; sutures deeply depressed; whorls convex, with a fairly well marked tabu- lation on the upper border; surface of body whorl ornamented with about 27 to 30 medium to coarse longitudinal ribs; surface also possesses 11 to 13 revolv- ing ribs, which are more prominent and nearer together than the longitudinal ribs; interspaces between revolving ribs much smaller than width of ribs; the juncture of the two sets of ribs gives the surface a nodose aspect, but frequently due to the lesser prominence of the longitudinal ribs, the spiral lines become the more pronounced; on the spiral whorls only seven of the spiral ribs are seen; outer lip sometimes possesses a rope-like varix; canal short, reflexed, and separated from the posterior part of the body whorl by a deep, rounded depres- sion; inner lip not preserved; columella appears to be smooth, but better preserved specimens may show plications. Dimensions.—Type specimen U. C. no. 12387; alt., 14 mm.; greatest width, 9mm. Cotype, U. C. no. 12388; alt., 13.5 mm.; greatest width, 7.8 mm. Occurrence.—This is a very common species throughout the entire Briones formation. Type from U. C. loc. no. 3524; cotype from loc. no. 1176, Named in honor of Professor F, L. Whitney, Professor of Paleontology at the University of Texas. This species differs from N. pabloensis Clark** in that it is more convex and it possesses more numerous longitudinal and spiral ribs. It differs from N. arnoldi Anderson’? in that it is larger and it pos- sesses more numerous and less prominent ribs. 28 Clark, Univ. Calif. Publ. Bull. Dept. Geol., vol. 8, p. 493, pl. 65, figs. 8 and 9, 1915. 29 Anderson, Proc. Cal. Acad. Sci., ser. 3, vol. 2, p. 204, pl. XVI, figs. 70 and 71, 1905. 1922] Trask: The Briones Formation of Middle California iS a Family BuccrnipaE Genus SIPHONALIA Adams SIPHONALIA RODEOENSIS, n. sp. Plate 7, figures 4a and 4b Type.—No. 12389, Univ. Calif. Mus. Pal. Shell fusiform; spire of medium height; sutures moderately appressed; whorls subangulate above the middle and slope gently up to the suture; surface of whorls with about ten longitudinal ridges, which are more pronounced upon the spiral whorls, and are more prominent at the point of angulation of the whorls; shell sculptured with numerous spiral ribs, which tend to become obsolete on the body whorl; on the whorls of the spire there are three major revolving ribs alternating with two minor ribs; inner lip smooth; canal medium in length and gently reflexed; umbilicus subperforate, Dimensions.—Type specimen U. C. no. 12389; alt., 30.5 mm.; greatest width, 17.8 mm.; alt. of aperture, 21.5 mm. Occurrence.—Briones formation. Type from U. C. loe. no. 1177, on the north side of Rodeo Creek. This species resembles S. danvillensis Clark,®° found in the Upper San Pablo, but it differs from the latter in that the angulation on the whorls, particularly on those of the spire, is not so pronounced; the surface of the whorls above the point of angulation slopes upward toward the suture and is not depressed as in S. danvillensis; there are no spiral ribs above the angulation; and there is a pronounced alter- nating arrangement in size of the revolving ribs on the spiral whorls. Family Murticipar Genus TROPHON Montfort TROPHON DAVIESI, n. sp. Plate 7, figures 5a and 5b Type.—No. 12391, Univ. Calif. Mus. Pal. Shell medium in size; spire about one-third height of shell; suture slightly appressed; body whorls five, with a flat, somewhat upward sloping tabulation; body whorl large, with depression about midway from angulation to base of whorl; outer lip not preserved; inner lip inerusted; canal moderately long and recurved; umbilicus subperforate. Dimensions.—Type specimen U. C. no. 12391; alt., 42 mm.; greatest width, 29 mm.; alt. of aperture, 28 mm. Occurrence.—Briones formation. Type from U. C. loe no. 1354. Named in honor of my mother, Kate Davies Trask and my uncle, Dr. M. J. Davies. 30 Clark, Univ. Calif. Publ. Bull. Dept. Geol., vol. 8, p. 497, pl. 67, fig. 6, 1915. 156 Umwversity of California Publications in Geology [Vou. 18 This species differs from 7. ponderosum Gabb*! in that it possesses a longer body whorl, longer canal, and a depression of the body whorl near the base. T. daviesi, n.sp., resembles 7. carisaensis (Anderson)*? in pos- sessing the depression on the lower part of the body whorl, but in the latter the depression is much more strongly developed and takes the form of a groove. T. daviesi further differs from 7. carisaensis in that it is less solid, more slender, and less prominently nodose. TROPHON GRACILIS CLARKI, n. nom. Plate 6, figures 2, 3, and 4 Trophon gracilis pabloensis. Clark, B. L., Univ. Calif. Publ. Bull. Dept. Geol., vol. 8, p. 498, pl. 66, figs. 6 and 7, 1915. Type.—No. 11625; cotype—No. 11626; Briones cotype—No. 12390. “Shell medium-sized; spire rather high; apex acute; number of whorls to spire five or six; body whorl large; sutures obscurely appressed. Whorls angulated, with the narrow surface above the angulation sloping up gently to the suture. Surface of shell crossed by ten or eleven prominent lamella-like varices which are flexed forward and produced on the angle into upright, fairly prominent spines; on the upper whorls of the spire the varices become prominent ridges. Spiral ribbing lacking; outer lp sharp; inner lip smooth and incrusted; canal broken on all specimens that the writer so far has obtained.’’ Dimensions.—Clark’s type, U. C. no. 11625; alt., unknown; max. width, 32 mm. Clark’s cotype, U. C. no. 11626; alt., unknown; max. width, 26 mm. Author’s eotype, U. C. no. 12390; alt., 53.7 mm.; max. width, 30 mm.; alt. aperture, 33.6 mm. Occurrence.—Clark’s type and cotype are from the Lower San Pahlo, U. C. ’ loc. no. 409. The writer’s cotype is from the Briones, U. C. loe. no. 177. Clark in this paper deseribed two varieties of different species of the genus Trophon, to both of which he ascribes the name “‘pablo- ensis,’’? n. var. Hence to avoid dupleation of terms, this variety has been renamed in honor of Professor Clark. In one of the specimens in the Briones the canal has been preserved and the following may be added to Clark’s description: Aperture elongate ; canal moderately long and recurved ; umbilicus subperforate. This canal is very similar to that of Trophon gracilis (Perry) ,*? and hence further shows the relationship of this variety to that species ; but the differences noted by Clark in his description seem to be sufficient to warrant making this form a distinct variety. 31 Gabb, op. cit., vol. 2, p. 2, pl. 1, fig. 3, 1869. 32 Anderson, op. cit., p. 206, pl. XVII, figs. 90 and 91, 1905. 33 Perry, Conch., pl. IX, fig. 4. 1922] Trask: The Briones Formation of Middle California 157 Note.—In the specimens found in the Briones formation the varices are not so pronounced as those from the Lower San Pablo; but the Briones forms appear to be somewhat eroded, and since they are similar to the Lower San Pablo forms in other respects, they are ascribed to the Lower San Pablo species. Family THAISIDAE Genus ACANTHINA Fischer de Waldheim ACANTHINA PERRINI, n. sp. Plate 8, figures la and 1b Type in Stanford University Paleontological Collection. Shell small to medium in size; whorls four; body whorl about two-thirds the height of the shell; sutures appressed; whorls with a prominent angulation, which on the body whorl is a little above the middle; on the whorls of spire angulation comes just above the suture; surface posterior to angulation slopes upward at an angle of about 45°; whorls with about eleven nodes on line of angulation, which are more prominent on the posterior whorls of the spire, where the nodes might be classed as longitudinal ribs; these nodes tend to become obsolete upon the body whorl; surface smooth except where lines of growth form depression on lower part of shell, which is characteristic of this genus; canal short, recurved; inner lip smooth; outer lip not preserved. Dimensions.—Type specimen alt., 32.5 mm.; max. width, 26.3 mm.; alt. of aperture, 21.8 mm. Occurrence.—Briones formation?. About six miles south of Livermore. Type in Stanford University collection. Named in honor of Professor James Perrin Smith, Stanford University. This species is quite distinct because of its low spire and broad body whorl. Genus KOTLOPLEURA, n. gen. Plate 8, figures 2, 3a, 3b, 4a, and 4b Type.—No. 11900; Cotype—No. 12393, Univ. Calif. Mus. Pal. Shell solid, elongate, medium spire; sutures deeply impressed, bordered by a raised tabulation; lower part of body whorl with prominent angulation, below which the shell rapidly narrows to form the canal; surface of shell between angulations markedly concave; outer lip with spine, causing pronounced narrow depression on lower part of body whorl below lower angulation; canal moderately long, rather wide, very deep, and curved posteriorly; umbilicus pronounced and subperforate. Dimensions.—Genotype specimen U. C. no. 11900; alt., 35 mm.; greatest width, 20 mm.; alt. of aperture, 27 mm. Cotype, U. C. no. 12393; alt., 49 mm.; greatest width, 24 mm.; alt. of aperture, 27 mm. Occurrence.—Briones formation (Upper Miocene). Type from U. C. loe. no. 13854; cotype from loc. no. 1455. 158 University of California Publications in Geology (Vou. 138 This fossil has hitherto been regarded as belonging to the genus Agasoma Gabb.** English*® in his description of the genus Agasoma stated that there were two sections of that genus, but he did not give them separate names. He stated: ‘‘The first section includes only A. sinuatum Gabb, with the narrow mouth opening; narrow, deep, medium length, recurved canal; and the pronounced angulation of the body whorl. The second ineludes the other species with evenly rounded, ventricose body whorl, and shallow wide canal.’’ This second section is the typical Agasoma described by Gabb. In view of the spine on the outer lip; depression on lower part of body whorl; pronounced subperforate umbilicus; and canal similar to Acanthina Fischer de Waldheim,** it appears that this form shows a closer relationship to Acanthina than to Agasoma. It differs from Acanthina, however, in possessing a deeply channeled suture, a pro- nounced collar; and two angulations on the body whorl with the pronounced coneavity between. Hence, due to these differences from Acanthina it is regarded as a new genus. Since it shows a closer relationship to Acanthina than to any other genus it is placed in the Thaisidae family. The word ‘‘Koilopleura’”’ is derived from xoiAos, concave, mAeupa, side. Genus KOILOPLEURA, n. gen. KOILOPLEURA SINUATA (Gabb) Clavella sinuatum. Gabb,87 Calif. State Geol. Surv., Paleontology of Cal- fornia, vol. 2, p. 5, 1869. Agasoma sinuatum, Gabb, Calif. State Geol. Surv., Paleontology of Calif,, vol. 2, p. 46, pl. 1, fig. 7, 1869. Agasoma sinuatum Gabb. English, Univ. Calif. Publ. Bull. Dept. Geol., vol 8, p. 250, pl. 25, figs. 5 and 6, 1914. Type.—No. 11994; cotype—No. 11995, Univ. Calif. Mus. Pal. An examination of Gabb’s types, which are quite small specimens, shows that what Gabb has taken for the convex portion in the middle of the body whorl is the rounded lower angulation which becomes so prominent in the older specimens. Between the two angulations there is the same pronounced concavity seen in the larger specimens. 34 Gabb, Pal. of Calif., vol. 2, p. 46, 1869. 35 English, W. A., The Agasoma-like Gastropods of the California Tertiary, Univ. Calif. Publ. Bull. Dept. Geol., vol. 8, p. 245, 1914. 36 Fischer de Waldheim, Mus. Demid, 1806. 37 Shell elongated, rather slender; spire low, convex; whorls four; suture deeply channeled, bordered by a thickened rim; body whorl convex in the middle, broadly grooved above, and excavated below; aperture long and narrow; columbella sinuous, slightly incrusted; outer lip simple; canal slightly recurved. 1922] Trask: The Briones Formation of Middle California Family O.ivipaE Genus OLIVA Brugiére OLIVA SIMONDSI, n. sp. Plate 8, figures 5a and 5b Type.—No. 12394, Univ. Calif. Mus. Pal. Shell medium sized, solid, econiform; spire one-third height of shell; whorls it 9 five, smooth and flat; pillar with two strong plications, with a smaller one between; callous extends half the distance from posterior to anterior end of aperture, and extends around to the posterior canal; outer lip not preserved. Dimensions.—Type specimen U. C. no. 12394; alt., 36.8 mm.; greatest width, 23 mm.; alt. of aperture, 30.3 mm. Occurrence.—Briones formation, U. C. loc. no. 171. Named in honor of Professor F. W. Simonds, University of Texas. This species is very close to O. peruviana coniformis Philippi** in shape, but it differs from the latter in that it possesses a small plication between the larger two, while in O. peruviana comformis the smaller plication is posterior to the two larger. KEY TO LOCALITIES Millimeters Millimeters Locality east* south* Quadrangle 15 147 155 Coneord 146 68 264 Mt. Diablo alyAl 222 29 Coneord 177 208 9 Concord 409 342 353 Mare Island 1176 35 427 Carquinez 1177 27 411 Carquinez 1354 One mile southeast of Muir Station. Coneord 1455 54 256 Mt. Diablo 1492 80 275 Mt. Diablo 1942 321 193 Coneord 1949 325 196 Coneord 3522 283 210 Concord 3524 281 223 Concord 3529 170 223 Pleasanton 3532 78 feet south loc. 3529. Pleasanton 3534 33 feet south loc. 3529. Pleasanton 35385 58 feet south loc. 3529. Pleasanton 3575 24 225 Mt. Diablo 3576 Near San Pablo Bay. Mare Island 3581 216 378 Pleasanton 3582 218 377 Pleasanton Formation Briones Briones Briones Briones Lower San Pablo Briones Briones Briones Briones San Pablo San Pablo San Pablo Briones Briones Briones Briones Briones Briones Briones Briones Briones Briones * Measurements in these two columns refer to distances in millimeters on the map, east and south, respectively, from northwest corners of the topographic sheets. 38 Philippi, Abb. u. Beschr., xix, 1, figs. 5-7, 1842-1851. EXPLANATION OF PLATE 1 Fig. la. Leda furlongi, n.sp. X 2. Dorsal view. Type.—No. 12362, Univ. Calif. Mus. Pal., loc. 15. Briones. Fig 1b. Leda furlongi, n.sp. X 2. Right valve of type. Fig. 2. Pecten raymondi brionianus, n, var. X 1. Left valve. Type.—No. 12368, Univ. Calif. Mus. Pal., loc. 3532. Briones. Fig. 8. Pecten raymondi brionianus, n. var. X 1. Left valve. Cotype.—No. 12369, Univ. Calif. Mus. Pal., loc. 3532. Briones. Fig. 4. Pecten raymondi Clark. X 1. Right valve. Type—No. 11581, Univ. Calif. Mus. Pal., loc. 1492. San Pablo. Fig. 5. Pecten andersoni gonicostus, n. var. X 1. Right valve. Type.—No. 12370, Univ. Calif. Mus. Pal., loc. 1176. Briones. Fig. 6. Pecten raymondi Clark. % 1. A very large specimen of the convex left valve.. No. 12871, Univ. Calif. Mus. Pal., loc. 1942. Upper San Pablo. [160] UNIV CALLR. RUBE. BULL, DEPT, GEOL. SCI, PRRAS Kiev Clie dicta rie ss EXPLANATION OF PLATE 2 Fig. 1. Pecten ricei, n.sp. X 1. Left valve. Type.—No. 12364, Univ. Calif. Mus. Pal., loc. 3585. Briones. Fig. 2. Pecten riceit, n.sp. X 1. Calif. Mus. Pal., loc. 3534. Briones. Right valve. Cotype.—No. 12365, Univ. [162] UNIV. CALIF rUB ERS WLEn DEP GEOL Scelr DERASKIPV.OE, Te) Rie oh EXPLANATION OF PLATE 3 Fig. 1. Pecten tolmani Hall and Ambrose, X 1, showing convex left valve. This species has never before been figured. It was first described by Hall and Ambrose in Nautilus, vol. xxx, p. 82, 1916. Type is in Stanford University Paleontological Collection. Specimen figured is No. 12367, Univ. Calif. Mus. Pal., loc. 3581. Briones. Fig. 2. Modiolus gabbi subconverus, n. var. X 1. Type.—No. 12372, Univ. Calif. Mus. Pal., loc. 793. Briones. Fig. 3. Pecten tolmani Hall and Ambrose, X 1, showing flat right valve. Specimen figured is no, 12366, Univ. Calif. Mus. Pal., loc. 3581. Briones. Fig. 4. Modiolus veronensis, n.sp. X 1. Type—No. 12373, Univ. Calif. Mus. Pal., loc. 3529. Briones. Fig. 5a. Cyrena diabloensis, n. sp. X 1. Exterior view. Type.—No. 12374, Univ. Calif. Mus. Pal., loc. 1949. San Pablo. Fig. 5b. Cyrena diabloensis, n.sp., X 1, showing dentition. Type. [164] UNM CAE TE WeUBiEY BUELL Deri. GEOL, SCi, [ TRASK ] VOL. iy EXPLANATION OF PLATE 4 — Fig. 1. Pecten vickeryi, n.sp. X 1. Left valve. Type in Stanford Univer- sity Paleontological Collection. Briones. Fig. 2a. Spisula falcata brioniana, n.var. X 2. Right valve, showing dentition. Type.—No. 12380, Univ. Calif. Mus. Pal., loc. 3522. Briones. Fig. 2b. Spisula falcata brioniana, n. var. X 2. Exterior view. Type. [166] PL. 4 [TRASK] VOL. 18, BULL PERI GEOR S Gir PUBL. UNIV, CALIF. EXPLANATION OF PLATE 5 Fig. 1. Venus brioniana, n.sp. X 1. Right valve. Type.—No. 12377, Univ. 5 Calif. Mus. Pal., loc. 177. Briones. Fig. 2a. Antigona willisi, n.sp. X 1. Dorsal view. Type.—No. 123879, Univ. Calif. Mus. Pal., loc. 146. Briones. Fig. 2b. Antigona willisi, n.sp. X 1. Right valve of type. Fig. 3. Cardium corbis (Martin), n.var.? X 1. Left valve. Specimen figured is no. 12376, Univ. Calif. Mus. Pal., loc. 207. Briones. [168] WING. (CAEIEs “PUBL: BULLE, DEPT. GEOL, SGI. [TRASK I V@lLr 13) PE EXPLANATION OF PLATE 6 Fig. la. Tivela merriami, n.sp. X 1. Right valve, exterior view. Type.— No. 12378, Univ. Calif. Mus. Pal., loc. 3582. Briones. Fig. 1b. Tiwela merriami, n.sp. X 1. Right valve of type, showing den- tition. Fig. 2. LTrophon gracilis clarki, n.nom. Type.—No. 11625, Univ. Calif. Mus. Pal., loc. 409. Lower San Pablo (Cierbo). Fig. 3. Trophon gracilis clarki, n. nom, Cotype—No. 12390, Univ. Calif. Mus. Pal., loc. 177. Briones. Fig. 4. Lrophon gracilis clarki, n. nom. Cotype.—No. 11626, Univ. Calif. Mus. Pal., loc. 409. Lower San Pablo. [170] UNIV. CALIF, PU BL, BULLE DEPT, GEOE, SCF [TRASK ] VOL, 13; RE. 6 EXPLANATION OF PLATE 7 Fig. la. Calliostoma obliquistriata, n.sp. X 2. Type—No. 12385, Univ. Calif. Mus. Pal., loc. 3575. Briones. Fig. 1b. Calliostoma obliquistriata, n.sp. X 2. Type. Fig. 2a. Sinum trigenariwm, n. sp. X 1. Type—No. 12386, Univ. Calif. Mus. Pal., loc. 3576. Briones. Fig. 2b. Sinwm trigenarium, n.sp. X 1. Type. Fig. 3. Nassa whitneyi, n.sp. X 1. Type.—No. 12387, Univ. Calif. Mus. Pal., loc. 3524. Briones. Fig. 4a. Siphonaltia rodeoensis, n.sp. X 1. Type—No. 12389, Univ. Calif. Mus. Pal., loc. 1177. Fig. 4b. Siphonalia rodeoensis, n. sp. X 1. Type. Fig. 5a. Trophon daviesi, n.sp. X 1. Type.—No. 12391, Univ. Calif. Mus. Pal., loc. 1354. Briones. Fig. 5b. TLrophon daviesi, n.sp. X 1. Type. Fig. 6. Nassa whitneyi, n.sp. X 3 (approximately). Shows varix on outer lip. Cotype—No. 12388, Univ. Calif. Mus. Pal., loc. 1176. Briones. [172] UNIVE CAEL. (RUBE, BUELL, DEPT, GEOL, SCI. DERASKIEVOL 1G Rie 7 5a 6 ab . EXPLANATION OF PLATE 8 Fig. la. Acanthina perrim, n.sp. X 1. Type in Stanford University Pale- ontological Collection. Fig. 1b. Acanthina perrini, n.sp. X 1. Type. ; Fig. 2. Koilopleura sinuata (Gabb). X 1. Specimen figured is No. 11901, Univ. Calif. Mus. Pal. Briones. Fig. 3a. Koilopleura sinuata (Gabb). X 1. Genotype.—No. 11900, Univ. Calif. Mus. Pal., loc. 1854. Briones. Fig. 3b. Koliopleura sinuata (Gabb). X 1. This shows the narrow depres- sion on lower part of body whorl and the spine on the outer lip. Genotype. Fig. 4a. Hoilopleura sinuata (Gabb). X 1. Cotype of genus.—No. 12393, Uniy. Calif. Mus. Pal., loc. 1455. Briones. Fig. 4b. Koilopleura sinuata (Gabb). X 1. Cotype of genus. Fig. 5a. Oliva simondsi, n.sp. X 1. Type.—No. 12394, Univ. Calif. Mus. Pal., loc. 171. Briones. Fig 5b. Oliva simondsi, n.sp. X 1. Type. [174] UNIVG GALIF. (PUBL: WIC (S| y OIE, Stelle 3a RAS VOI 13, ES IVERSITY OF CALIFORNIA PUBLICATIONS «BULLETIN OF THE DEPARTMENT OF iy ss GEOLOGICAL SCIENCES see oe OF CALIFORNIA WITH SPECIAL REFERENCE TO THE ORIGIN OF THE NICKELIFEROUS PYRRHOTITE BY F. S. HUDSON JUL 19 19292 jf & 2tionat muses” ‘ eis UNIVERSITY OF CALIFORNIA PRESS BERKELEY, CALIFORNIA 13, No. 6, pp. 175-252, 7 text figures, 1 map, pls. 9-14 June 29, 1922 ;OLOGY OF THE CUYAMACA REGION * Ny GEOLOGICAL SCIENCES.—Anprew O. Lawson, Hditor. Price, volumes 1-7, $3.50 . Bird Remains from the Pleistocene of San Pedro, California, by Loye Holmes Miller. . Tertiary Echinoids of the Carrizo Creek Region in the Colorado Desert, by William . The Fernando Group near Newhall, California, by Walter A. English ..........2...::c--0 . Ore Deposition in and near Intrusive Rocks by Meteoric Waters, by Andrew C, . The Agasoma-like Gastropods of the California Tertiary, by Walter A. English........ . The Martinez and Tejon Eocene and Associated Formations of the Santa Ana . Remains of Land Mammals from Marine Tertiary Beds in the Tejon Hills, Cali- . The Martinez Eocene and Associated Formations at Rock Creek on the Western. . A Proboscidean Tooth aH 08 the Truckee Beds of Western Nevada, by John P. . Notes on the Copper Ores at Ely, Nevada, by Alfred R. Whitman ........0....-2c::secsse . Skull and Dentition of the Mylodont Sloths of Rancho La Brea, by Chester Stock. UNIVERSITY OF CALIFORNIA PUBLICATIONS WILLIAM WESLEY & SONS, LONDON Agent for the series in American Archaeology and Ethnology, Botany, Geological Sciences, Physiology, and Zoology. vrs = volumes 8 and following, $5.00. Volumes 1-12 completed; volume 13 in ‘progress. — list of titles in volumes 1 to 7 will be sent upon request. VOLUME 8 . Is the Boulder ‘‘Batholith’’ a Laccolith? A Problem in Ore-Genesis, by Andrew 2 Cu Lia W801 oes en cases eensnedasecteencsebiceoncupg cnoeconeaiu cet net oie ere oe or : Note on the Faunal Zones of the Tejon Group, by Roy E. Dickerson Teeth of a Cestraciont Shark from the Upper Triassic of Northern California, by Harold OC. Bryant | ..c....-.-ciicspcescseescovceteecececucenesecasnctbtoas done naeecnneee de Ace cae ae ; $S. SW, ROW cen c2c.ccesceeccnpceedeoeeonseseascctnsumnddnoutessscsupnassiditeste se ronShecuete Seat a . Fauna of the Martinez Eocene of California, by Roy Ernest Dickerson .......-----c-:--- . Descriptions of New Species of Fossil Mollusca from the Later Marine Neocene of California, by Bruce: Martin ....-..c.-.s.--ctcsceccessonectenncteseteteqctopebeneditas teers ThA W SOW Pisce cannscncweocseceeenancovapnopensenoendbcuennssacgsescanultcanenanapnasadesetdek uua¥ cet UCietse ret at er Mountains, by Roy E. Dickerson ® ..2...-..-.-:0:--t:-.cs0esstse-coseensescssoneneseencesheestes= = The Occurrence of Tertiary Mammalian Remains in Northeastern Nevada, by John — CO SMIORRT AI oon on anna nas acs neseenseete sense etearennsberansctopennecstecnaesdieanat Be cctahsea peat fornia, by John (C, Merriam \...222...2...-- secon bec ecccenntesseral senate cnesasnigeie to Border of the Mohave Desert Area, by Roy E. Dickerson ~..2........022.--::--scessnsseerseeseee New Molluscan Species from the Martinez Eocene of Southern California, by Roy HE IDICKCCT SOM Uo. once stccetsnnnnenen ce nen emcee nee rman nts meene ne Be ent are eta enna erate eee ee ee BU Wala ¢ >a: , One of the dense quartzose lenses, occurring in sillimanite gneiss, is composed of about 85 per cent quartz, the balance being basic plagioclase with a small amount of biotite. The writer has been unable to find any reference to rocks similar to these lenses in American geologic lterature. Harker and Marr have described the metamorphic effect of the Shap granite on the Lower Coldwell grit in Westmoreland. The unaltered rock is com- posed of subangular grains of quartz and feldspar, with some inter- stitial dusty matter like kaolin, and little patches of finely granular calcite. A specimen of the metamorphosed rock, from 600 yards from the granite contact, has a vitreous appearance and is made up of quartz, feldspar, and lime augite, the contacts of the minerals being ~sutural.*? Rosenbusch has described a number of quartz-pyroxene rocks from Alsace and southern Germany. They are classed in his para-pyroxene eneiss group, within which there is a wide range of mineralogic com- position.® With regard to the structure of these rocks he states:* ‘‘While the ortho-pyroxene-gneisses are usually distinctly schistose, this is very often not the case with the para-pyroxene-gneisses and their structure is typically hornfels-like.’’ A typical section through the schist series—The following is a section from the northeast edge of the main schist mass, immediately west of Banner, southwestward to the Julian-Cuyamaca road: Gneissoid granodiorite. 60 feet Injection gneiss. 300 feet 1. Quartz-two-mica schist with knots of muscovite. Coarser near the igneous contact, grades into next member away from contact. 700 feet 2. Medium grained quartz-mica schist, with quartzite layers. 400 feet 3. Medium grained quartz-two-mica schist. Large muscovite flakes at high angle to schistosity. ‘‘Rolled’’ lenses of quartz-pyrox- ene rock. 2 Harker, A., and Marr, J. E., Quart. Jour. Geol. Soc., vol. 47, 1904, p. 321. 3 Rosenbusch, H., Elemente der Gesteinslehre, 1910, pp. 617-619. 4 Ibid., p. 618. 1922] Hudson: Geology of the Cuyamaca Region of California 187 1500 feet 4a. Fissile, evenly banded, quartz-muscovite schist. Weathered surfaces resemble slate. Contains no quartzite. 40 feet 4b. Quartzite. 360 feet 4c. Fissile, fine-grained schist. 150 feet 4d. Quartzite, in part thin-bedded. 200 feet 4e. Fissile, fine-grained schist. 20 feet 4f. Quartzite, thin-bedded. 3000+ feet 5. Evenly banded, coarse quartz-mica schist, containing a few quartzite layers and some injected material. In part carries andalusite. Injection gneiss. Gneissoid quartz diorite. About one-half mile to the southeast practically the same sequence of rocks is present, save that here member 5 of the above section is represented by an equal or greater thickness of coarse, generally enarly, quartz-mica-silimanite gneiss and other paragneisses, with lenses of dense quartz-pyroxene rock. Origin of the schist series—The fissile schists composed chiefly of quartz and two micas and banded with numerous quartzite layers can hardly have had any other than a sedimentary origin. The layers of quartzite are essentially parallel to the schistosity, showing that the schistosity in general conforms to the original bedding. Whether there is isoclinal folding or not cannot be said. These rocks are thought to have resulted from the metamorphism of a series of shales and fine- grained, clayey sandstones, with beds of nearly pure quartz sandstone. The amphibolite and actinolite schists, on the other hand, if we may judge from their mineral composition and mode of occurrence, are probably derived from andesitie or basaltic lavas. The sillimanite gneiss, andalusite gneiss, and other paragneisses as deduced from their mineral composition differ in no way chemically from the fissile schists, leaving out of account, of course, the igneous or pegmatitic injected matter. The presence of quartzitic lenses and alternating layers of varying mineral composition proves their sedi- mentary origin, and they are therefore thought to have been derived from the same types of sediments as were the fissile schists. The contorted or gnarly character of many of these rocks is prob- ably due to a second schistosity imposed on an earlier. In support of this interpretation is an example from the coarse quartz-mica schist, number 5 of the section given on this page. The rock is an evenly banded, medium grained quartz-mica schist in which the schistosity is parallel to the original bedding. The banding strikes K—W and dips vertically. There is another set of planes in the rock which eurve 188 University of Californa Publications in Geology [Vou. 138 so as to be inclined at a high angle to the even banding and then merge into it. Along these curving planes are layers of coarse mus- covite flakes. This rock probably represents an intermediate stage between the fissile schists and the gnarly textured gneisses. Conclusions —The Julian schists are the product of metamorphism of a series of shales, fine clayey sandstones, and nearly pure quartz sandstones, with subordinate layers of basic voleanie rock. In the less metamorphosed portions the schistosity is parallel to the original bed- ding of the rock. In the intensely metamorphosed portions there is evidence of two directions of schistosity, the earlier conforming to the original bedding, the later at a varying angle to it. The rocks exhib- iting the double schistosity are characterized by peculiar minerals generally ascribed to contact metamorphie action, 1.e., sillimanite and andalusite. The intrusive quartz diorite is without doubt responsible for these contact minerals. There seems some reason, therefore, to attribute the later schistosity to the action of the intrusion. The earlier schist- osity is attributed to a time earlier than the intrusion. Further evi- dence that the rocks were schistose before the intrusion of the quartz diorite is found in the extensive development of lit par lit injection gneisses and the total absence of hornfels along the contacts. Age of the Julian schists —The earliest ideas that are of any value in this discussion are those of Fairbanks.* In a paper on the geology of San Diego, Orange, and San Bernardino counties he reports finding fossils in limestone, inclosed in black shale and sandstone, four miles up a canon which comes from the northeast and enters Silverado Canon near its mouth. This seems to refer to Ladd Cafon, south of Sugarloaf Peak in the Santa Ana Mountains. (Shown on Corona Quadrangle map, U. 8. G. 8.) These fossils were sent to the National Museum and pronounced Carboniferous. Fairbanks concluded that the metamorphic rocks of the Santa Ana Mountains were equivalent to the erystalline schists of the Julian gold belt. He continues: This is a belt of schists which runs through the heart of the Peninsula range, from the Mexican line through the Santa Ana Mountains. ... . I believe that there is no question but what the metamorphic rocks of the Santa Ana range are equivalent in age to a large part of those in San Diego county. Although none but Carboniferous fossils were found, it is probable that the Metamorphic Series contains rocks much older as well as younger. 5 Fairbanks, H. W., California State Mineralogist, Report (XI), 1893. 6 Ibid., p. 115. 7 Ibid., p. 118. 1922] Hudson: Geology of the Cuyamaca Region of California 189 J. P. Smith, in his paper on ‘‘The comparative stratigraphy of the marine Trias of western America,’’ says: Dr. H. W. Fairbanks has discovered in the Santa Ana Range, Orange County, California, some fossiliferous limestones with pelecypods resembling Daonella and a trachyostracan ammonite not generically identifiable. These beds prob- ably represent the Lower Trias, but the fossils are too scanty for a definite opinion to be based on them.8 The results of the work of W. C. Mendenhall have been published in the ‘‘Index to the Stratigraphy of North America.’’® He reports that the axis of the Santa Ana Mountains is made up of a series of dark-gray or black slates with minor amounts of inter- bedded brown sandstones, the whole sparingly intruded by a series of medium acid dikes and overlain unconformably by remnants of the associated effusives whose aspect is generally that of andesites or slightly more acidie rocks. The slates exhibit varying degrees of metamorphism. They usually have a well-developed cleavage, which, however, is generally not sufficiently perfect to obscure the original bedding planes. In general they resemble the Mariposa slate of central California, although as a rule they are less extensively altered. .... Both the sediments and the associated effusives have been intruded and slightly altered by great masses of granitic rocks, and this three fold series after a long time interval, represented by an extensive physical unconformity, has been at least partly buried under Cretaceous conglomerates and shales of Chico The determination of the age of the slates is based on small collections made in Ladd Canyon, on the south slope of the range, and near the mouth of Bedford Canyon, on its north slope. .... Dr. Stanton decided, in the case of the Bedford Canon collection, that the fossils are clearly Triassic. No mention is made of the determination of the Ladd Cafion collection, but presumably it also indicated a Triassic age. Quoting Mendenhall further : The Triassic beds probably extend considerably beyond the area in the Santa Ana Mountains where they have been carefully examined. Similar beds are known to occur in Railroad Canyon between Elsinor and Perris. .... Merrill in a recent publication applied the name ‘‘ Julian Group”’ to the crystalline schists of San Diego County. He says: The metamorphic formations are mica schists, slates, quartzites and lime- stone, the first being especially well exposed near Julian and the latter oecur- ring in small areas at several points. These metamorphic rocks, from their structural position and lithologic characters, may be regarded as probably equiv- alent to the Calaveras group described in the Mother Lode Folio of the U.S. Geological Survey and will be here designated as the Julian group. Their exact age is uncertain.10 8 Smith, J. P., Proc. Calif. Acad. Sci., ser. 3, vol. 1, 1904, p. 352. 9 Willis, Bailey, U. S. Geol. Surv. Prof. Paper, 71, pp. 505-506, 1912. 10 Merrill, F. J. H., ‘‘Geology and mineral resources of San Diego and Im- perial counties,’’ Calif. State Min. Bur., 1914, p. 12. 190 University of California Publications in Geology [Vou. 13 A fossil was found by Mr. D. D. Bailey of Julian in the small area of metamorphic rock that hes in the granite about a mile southeast of Banner. This was submitted by Mr. H. L. Huston of San Francisco to Dr. J. P. Smith, who pronounced it ‘‘a slender ammonite that is without much doubt Triassiec.’’4 The fossil is an imprint of an ammonite on the surface of an angular pebble of dark gray, quartzitic rock. It was found as float. The writer in company with Mr. Bailey visited the locality where this was found. The rocks of the vicinity are non-fissile, quartz-two-mica schists, sillimanite gneiss and blue-gray quartzite. Several hours’ search was not rewarded by the finding of any fossils, but consider- able rock similar in appearance to the matrix of the fossil specimen was seen. Correlation based on lithologic character—The conclusion has already been presented that the Julian schists were originally a series of shales, fine clayey sandstones, and pure quartz sandstones. The beds of the Santa Ana Mountains, as described by Mendenhall, would, if subjected to further metamorphism, yield schists much like those at Julian. The writer has examined the metamorphic rocks along Railroad Cafion, north of Elsinore in Riverside County, which were referred by Mendenhall to the Triassic on the basis of their lithologic similarity with the rocks of the Santa Ana Mountains. The prevailing rocks are dark slates and gray quartzites. Both a white and an impure facies of quartzite was seen and some of the slates are rather sandy. Within this series at one horizon oceur gray cherts interbedded with green shales. Lenses of fine-grained quartz-rhodonite-rhodochrosite rock are found lying parallel to the bedding within this sequence of chert layers. Similar occurrences of manganese minerals in chert lenses inclosed in small masses of metamorphie rocks which are in turn surrounded by granite are found a short distance northeast of Deer Park, and between Campo and Jacumba, in San Diego County. In these lenses metamorphism has been more severe so that rhodochrosite is lacking and manganese garnet occurs in addition to rhodonite. Moreover, the inclosing rocks are quartz-mica schists similar in appearance to the Julian schist. If these manganese-bearing cherts really belong to the Julian schist series, it is seen that there is a remarkable similarity between that series and the Railroad Cafion rocks. Practically the only difference is in the degree of metamorphism. 11 Oral communication. 1922] Hudson: Geology of the Cuyamaca Region of California 191 THE STONEWALL QuARTZ DiIoRITE The most widespread rocks of the mountainous portion of San Diego County are of plutonic type, varying from intermediate to acidic in chemical composition. Three specimens determined by Dr. A. S. Eakle from quarries near the towns of Lakeside, Foster, Santee, and Grossmont, at the western edge of the mountains, proved to be granites, while a fourth was granodiorite.? Farther to the northeast quartz diorite is the prevailing rock. It has been deseribed by Calkins, as follows: The dominant rock about Ramona, as well as westward to the foot of the mountain range, is one that would commonly be called a biotite granite. Its color is gray with a tinge of olive-green; its texture is moderately coarse. Feld- spar is its most abundant mineral, but quartz is also abundant, and small flakes of black mica occur in moderate quantity. Microscopic study shows that the rock is not a typical granite, inasmuch as the alkali feldspar is very subordinate to the soda-lime feldspar.13 Excepting a mass of true granite which will be described in a later chapter as the Rattlesnake granite, the granitic rocks of the Cuyamaea region are low or lacking in alkali feldspar and are to be classed as granodiorites and quartz diorites. In mineral composition they are much like the rock described by Calkins, and might well be correlated with it and termed the Ramona quartz diorite. However, as there may possibly have been more than one period of irruption of magmas of this nature, that of the Cuyamaca region will be termed the Stonewall quartz diorite, after the peak of that name composed of this rock. Petrographic description.—These rocks are medium to coarse- grained aggregates of quartz, plagioclase, biotite, and rarely orthoclase. The plagioclase varies from albite to andesine, and in one specimen, from a dark segregation, it is labradorite. Green hornblende occurs in the dark segregations. Orthoclase is present in only three out of fourteen specimens examined, and in these makes up less than 10 per cent of the rock. In part of the area mapped the quartz diorite is distinctly gneissoid, in other localities, as in the neighborhood of Stonewall Peak, the eneissoid character is barely discernible or completely lacking. This 12 Mines and mineral resources of Imperial and San Diego counties, Calif. State Miner., Rept., 1913-1914, p. 43. 13 Calkins, F. C., Molybdenite and nickel ore in San Diego. County, California, U. S. Geol. Surv., Bull. 640, 1916, p. 74. £92 University of California Publications in Geology [Vou.13 gneissoid structure is generally best developed in the vicinity of con- tacts of the quartz diorite with the schist and is lacking at a distance from schist bodies. For instance, immediately east of the schist body south of the Friday Mine the rock is distinctly foliate. To the east of this point the gneissie structure becomes less prominent until one mile to the east, on approaching the main schist body, the rock again becomes quite gneissoid. The same change occurs on going west from the west boundary of the main schist belt north of Wynola. Again, the irruptive rock in the vicinity of the schist mass south of Cuya- maca Reservoir is gneissoid, while in rock of the same composition in Stonewall Peak and along the basic intrusive contact to the southwest the foliate structure is nearly or completely lacking. The strike of the gneissoid structure is always essentially parallel to that of the neighboring schist. The dip of the foliation in the intrusive rock often conforms to the dip of the schist. It is inferred that the gneissie structure is parallel to the walls of the schist bodies. An inspection of the map will show that some of the schist bodies have curving courses, notably those in the vicinity of Pine Hills. The struc- ture of gneiss and schist conforms even in these cases. It is therefore concluded that the gneissoid structure is not the result of the dynamic metamorphism of solid rock, but that it represents the flow lnes of a partially consolidated magma. Age of the quartz diortte-—The intrusive nature of the contacts of the quartz diorite and the Julian schist is evident from the occurrence of injection gneisses, paragneisses, and contact minerals along the con- tact. The Cuyamaca Basic Intrusive cuts across the structures of schist and quartz diorite gneiss and is undoubtedly younger than either. To the northwest of the Cuyamaea region, in the Santa Ana Range, and to the south, in the mountains of Lower California, Cretaceous rocks rest upon the eroded surface of great granitic masses. No in- stanees of post-Cretaceous granite are known in California. We can then with reasonable assurance say that the quartz diorite is pre- Cretaceous. From Mendenhall’s work in the Santa Ana Mountains we know that at least part of the granite of the Peninsular Range is post-Triassic. This leads to the conclusion that the Stonewall quartz diorite is pre-Cretaceous and post-Triassic, probably corresponding in age to the post-Mariposa granitic masses of the Sierra Nevada. Type of intrusion—The wide zone on the west side of the main belt of Julian schist, in which injected material and contact minerals 1922] Hudson: Geology of the Cuyamaca Region of California 193 are found, makes it probable that the intrusive contact dips at a low angle to the east beneath the schist body. The contact zone on the east side of the schist belt, while narrower than that on the west, is still so wide that it appears likely that the contact here also dips to- ward the schist. It is thus probable that the schist masses wedge out downward. The widespread occurrence of quartz diorite in the Cuya- maca and Ramona regions suggests that we have to deal with a great batholithic mass. Tue Cuyamaca Basic INTRUSIVE The main basic intrusive mass of the Cuyamaca Mountains, to- gether with the smaller outlying masses, presents many petrographical variations, but the rocks of which it is composed, with a few exceptions, may be grouped as gabbros, norites, and basic diorites. These rocks are of medium to fine grain, specimens having their largest mineral grains over 5 mm. in size being rare. In general the rocks have a maximum grain of from 1.5 to 4.0 mm. Despite the fine grain, the rocks never exhibit diabasic structure, and the porphyritie habit is exceptional. The rocks of the mass have been classified as diorites on the one hand and norites and gabbros on the other hand, according as their plagioclase feldspar contains more or less than 50 per cent of albite molecule. No attempt was made to mark off the norites from the gabbros during the field work. Even had the discrimination been possible in the field, the complex intermingling of the two types and the heavy soil cover would have rendered their separate mapping im- practicable. It can, however, be said that norites are more abundant than gabbros in the immediate vicinity of the Friday mine, and also in the embayment in sections 16 and 17, township 13 south, range 4 east, and in the outlying area to the northwest of that embayment. Gabbro predominates over norite in the region west of Middle Peak and Cuyamaca Peak. As a result of microscopic study two areas of diorite have been roughly delineated. One of these, lying along Cedar Creek, two miles north of North Peak, is predominantly hypersthene diorite, but augite diorite and brown-hornblende norite are also pres- ent. The other area of diorite occupies the lobe of the basic intrusive mass that extends east, on the east flank of Cuyamaca Peak. It is characterized by augite diorite. Constituent minerals.—The various rock types are mixtures of a limited number of minerals, in varying proportions. 194 Umversity of Califorma Publications in Geology [Vou.13 The feldspars range from oligoclase to anorthite. Under the micro- scope they are seen to be almost invariably twinned according to the albite law. Combinations of albite and carlsbad or albite and pericline twinning are frequent. The hypersthene, to the unaided eye, has rather light colors, in- cluding pale brown and pinkish tints. These colors would indicate enstatite, but microscopic examination shows the mineral to have always a negative sign. The pleochroism is buff to pink for the fast ray, very pale green for the slow ray. In many of the thin sections examined a mineral was seen having all the properties of hypersthene except that it seemed to show oblique extinction. A more careful examination showed that this was not oblique extinction, but sym- metrical extinetion, in which one of the two sets of cleavage lines was poorly developed. There is no reason then to regard this mineral as other than hypersthene. It is possible that ‘‘a pleochroie augite pre- cisely like the hypersthene, but with a distinct extinction angle,’’ de- seribed by Coleman’® from the Sudbury norites, is of the same nature. The augite appears black in the hand specimen. Under the micro- scope it shows a maximum extinction angle of 55°, is colorless to pale buff, and frequently is filled with an opaque dust. The brown hornblende appears black to the unaided eye. Its micro- scopic properties are as follows: Pleochroic: a= colorless, faint green, but generally pale buff; 6, e— dark shades of brown; absorption, b>c>a. The sign is negative, the extinction angle 28°, the maximum birefringence .026. In hand specimens entirely unaffected by weathering, the olivine appears colorless or very faint green, and is transparent. With in- creasing weathering the olivine becomes yellowish and finally red. In thin section the olivine is colorless or very faint green. Its sign is negative. The green hornblende appears dark green megascopically. Under the microscope it shows the following colors: a= greenish yellow or pale buff; 6—dark brown-green, dark green or light brown-green ; c—dark green to pale yellow green; absorption, b>c>a. The maxi- mum extinction angle is 30°, the sign negative. Besides these essential minerals there are certain minor constit- uents. Apatite needles are found in almost all the rocks. Green spinel, pleonaste, is frequently present, associated with the magnetite. No picotite or chromite was noted. Every specimen of basic rock ex- amined contained either pyrrhotite or magnetite or both. The biotite, 13 Coleman, A. P., Rept. Bur. Mines Ont., vol. 14, pt. III, 1905, pp. 115-116. 1922] Hudson: Geology of the Cuyamaca Region of California 195 found in certain of the border facies, differs in no way in its optical properties from that of the gneisses. Its pleochroism is yellow to almost colorless, parallel to the principal axis, deep brown to black, parallel to the cleavage. The quartz seems to be identical with that of the more siliceous rocks. Description of typical rocks.—Fifteen types of basic igneous rocks have been recognized in this region. In order to give an idea of the mineralogic composition and texture of these rocks a detailed petro- graphic description of ten specimens, typical of as many varieties of rock, will be presented. The five varieties not described—augite dio- rite, brown-hornblende gabbro, gabbro-norite, olivine gabbro-norite, and quartz gabbro-norite—differ not at all in texture from the types described. As their names indicate, their discrimination from the other types depends either on some minor, though characteristic, con- stituent, or on a difference in the relative proportion of common con- stituents, or on a difference in the kind of plagioclase. Norite (no. 151, pl. 9, fig. 1), from the small area of basic rock one and one- half miles east of Pine Hills. This rock has the following composition: SAIN AHS, Soe eee eee ee Hypersthene AU GIG C) ao. oes 2ecee aces acuseres sesececest senestece : Brown Hornblende .................... 2% Py rrhowlte = 2252 ecssecsscecsteeses 2% The maximum size of grain is 2.3 mm., the average about 0.5 mm. The plagioclase and pyroxenes have mutually interfering, irregular boun- daries, made up of a series of curves. There is little tendency toward euhedral outline on the part of any of the constituents. The brown hornblende occurs both as rims on the hypersthene individuals, lying between the hypersthene and the feldspar, and as separate patches within the hypersthene. In both cases it is clear and compact. An individual of brown hornblende, shown in plate 9, figure 2, at one place has irregular, branching arms between several feldspar grains. Optically it is one individual throughout. The pyrrhotite occurs in grains up to 0.8 mm. in diameter. These grains are frequently quite irregular in outline, having two or more branches from their main body. However, many of the sulphide grains have extremely simple form, being circular or slightly oval in section. The most irregular grains invariably are found filling spaces at the meeting of several silicate individuals, quite like the hornblende, mentioned above. The grains with circular and oval sections, on the other hand, are always completely inclosed within a single silicate indi- vidual, generally a pyroxene. The pyrrhotite occurs most commonly at the edges of pyroxenes, extending thence into feldspar. Sometimes the pyrrhotite is separated from the pyroxene by brown hornblende. This, however, is not the result of any reaction between the ore mineral and the pyroxene, but is part of an ordinary hornblende ‘‘rim’’ which on either side of the grain of ore lies between the pyroxene and feldspar. Olivine norite (no. 190, pl. 9, fig. 3), from summit of hill south of Pine Hills. 196 University of Califorma Publications in Geology [Vou.18 The mineral composition is as follows: BiG OWL ence ee erence 54% EiiyPeTS then en cceecseescecsse sees 24% BENS BT: © ie ee 4% Olivine) 2.22 ae eee ee 16% TEA VAtAH OWE Ss eee eee rere rece eee 29% The average grain is 0.7 mm., the maximum 2.0 mm. Both hypersthene and augite are in some instances molded against crystal- lographic boundaries of the feldspar. Some of the pyroxenes are then probably later than part of the feldspar. There is, however, little tendency to diabasic texture, most of the constituents meeting in curving contacts. The olivine occurs in nearly equant grains with irregular rounded outlines. These grains are found both within the pyroxene and the feldspar. In the latter situation a kelyphitic zone separates the olivine from the feldspar. These zones, as in specimen no. 70, are composed of compact amphibole within and a fibrous mineral without. The olivine appears to be the earliest silicate. Its crystallization was fol- lowed by that of the feldspar and pyroxene, whose periods overlapped, so that most of the pyroxene is later than at least part of the feldspar. The pyrrhotite is found in association with all the silicate minerals. Its grains have not very complex outlines, those entirely inclosed in single olivines having particularly simple, circular sections. Gabbro (no. 202), from a caiion running northwest from Cuyamaca Peak, at 5000 feet elevation. The mineral composition of this rock is as follows: Bytownite Oia ata EyperSthien eC: ies cesses eet 13% NUDE C weit sicssseestctiaet is eedssssecerne ees 27% Green Hornblende ..................... 4% DNUEfe§ oleh i Boyes meee eee So emote ee 3% SPsyarm ODI Cie seers see eens eee eee eee 0.37% SPUN ye es eee eo eee Very small amount The average grain is 0.5 mm., the maximum 1.5 mm. The augite occurs in large individuals with irregular rounded outline. In some cases branching masses extend out from the main mass of an individual, the whole being an optically continuous body. This is illustrated by plate 9, figure 4. The augite frequently includes grains of feldspar poikilitically. The hypersthene, like the augite, shows ophitic texture, but the external outline of its individuals are much more regular. Both pyroxenes generally have mutually interfering, curving boundaries against the feldspar, but in a few cases the hypersthene is molded against crystallographic planes of the feldspar. Apparently all of the pyroxene crystallized after at least a portion of the feld- spar. Compact, light green hornblende forms rims on the augite, sometimes so extensive as to leave very little augite. The hornblende and augite appear to be crystallographically continuous. The pyrrhotite occurs in grains up to 0.2 mm. in diameter. The largest grains are within, or in contact with, pyroxenes, but much of the pyrrhotite is entirely inclosed in feldspar. Most of the grains have rounded irregular outlines, in 1922] Hudson: Geology of the Cuyamaca Region of California 197 no case, however, so irregular as that of the augite mentioned above. On the other hand, there are several sulphide grains, entirely enclosed in single feld- spars which have almost perfectly circular outlines. The spinel occurs in minute, irregular grains. The magnetite generally shows irregular forms, with rounded outlines, much like those of pyrrhotite. The re- lations between the spinel and magnetite, shown in plate 9, figure 5, point to a close genetic connection. Olivine gabbro (no. 130), from point about one mile north of North Peak. On road northeast of sawmill. The mineral composition is as follows: Bytownite Olivine .......... on PU eR Hey Bee eeer eereten eere Brown hornblende ...................... 9% De alg CKO pee 1% The average grain is 0.4 mm., the maximum 1.0 mm. All the constituents show mutually interfering, curving outlines. Many of the olivine grains are rimmed with hypersthene, in just the same way that the augite individuals are rimmed with brown hornblende. The hypersthene rims often show optical continuity for more than one-quarter the circumference of the olivine grains, in one case for more than one-half the eir- cumference. The brown hornblende sometimes makes up over one-half of a erystallographically continuous, compound individual with augite. The pyrrhotite occurs within the mineral individuals, rather than at the contacts of dissimilar minerals. The pyroxenes contain more pyrrhotite than does the olivine, the feldspar least of all. When entirely inclosed in individual minerals the pyrrhotite shows extremely simple outlines, circular or oval. Brown-hornblende norite (no. 108), from north center of northwest quarter of section 20, township 13 south, range 4 east. The mineral composition is as follows: Labradorite -~...............2...0.0--eee 46% HELV) OMS TCT Oy sesees ceeeeee ce eceeseseeeee 20% Brown Hornblende ................... 25% PATA D ULC oeceescee cca ste seeecegeee ean oe 6% Mian 6 tte: ees secere vesree rece eres 2.4% Pryrrh tite ? vicezsccscasecesctczscect-eesevecece 0.6% The average grain is 0.3 mm., the maximum 0.8 mm. The hypersthene, augite and plagioclase have mutually interfering, curving boundaries. The brown hornblende is seen as euhedral sections, entirely enclosed in feldspar, and also occurs in completely anhedral fashion, molded against crystallographic planes of the feldspar. It is generally found implanted on the ends of hypersthene individuals. Some of the hornblende then seems to have crystallized before at least part of the plagioclase, while some is apparently later than all the plagioclase. The pyrrhotite is found generally at the boundaries between pyroxenes and feldspars, and the grains in such situations have rather complicated outlines. The few grains of ore that occur within single silicate individuals (in this rock, within feldspars) have simple circular or oval outlines. Periodotite (no. 60), from east wall of north cross-cut, 170-foot level, Friday Mine. 198 Unversity of California Publications in Geology [Vou. 138 The mineral composition is as follows: OU Vain e eae See eee 73% ANIL G2 2 ohh oatee oe sehen Rees ere 14% Brown hornblende ...................... 10% TE yaerel NOY AM SP rea ee aoe 3% Average grain is 1.2 mm. The olivine occurs in equant or slightly elongated grains, meeting in irreg- ular curving contacts. The augite is in large very irregular individuals including the olivine poikilitically. Pyrrhotite occurs in irregular masses, in part at the meeting point of three or more olivine grains, in part within single olivine grains. No sulphides occur in the augite or hornblende. Troctolite (no. 70), from point eight feet north of body of massive ore, 170- foot level, Friday Mine. The mineral composition is as follows: Bytownite OI alni(ey es veces Pyrrhotite Minerals of kelyphitic zones .... 7.0% No euhedral tendency is exhibited by either olivine or feldspar. The olivine occurs in part as separate, rounded grains, surrounded by feldspar, and also as strings of coalescing grains which give the rock a banded appearance (see pl. 9, fig. 6, and pl. 10, fig. 1). The olivine crystallized before the feldspar. The olivine grains are separated from the inclosing feldspars by rims or zones. These are of three kinds: (1) compact, faint brown or green, horn- blende. These are clear and often optically continuous for a considerable frac- tion of the circumference of the olivine grain. (2) Aggregates of green fibers, set at right angles to the periphery of the olivine. The fibers show inclined extinction and are probably a fibrous amphibole. (3) Compound zones, com- posed of compact hornblende within and fibrous mineral without. Green spinel, pleonaste, occurs in sharply angular grains in these zones. Pyrrhotite is associated with both the feldspars and olivines. Where lying entirely within single crystals its outlines are relatively simple. Hypersthene diorite (no. 124), from area of hypersthene diorite, two miles north of North Peak. The mineral composition is as follows: PASTIIC GS it) Cua smears sane eee 70% EI yp CISL WCC secre eee eee 9% Green Hornblende .....................- 19% Wiel OW CCI Ocean acezcecsu=ecescncreceec=e = 1.7% The average grain is 0.3 mm., the maximum 2.5 mm. There is little tendency toward euhedral outline on the part of any of the constituents. They meet in curving lines, as is shown in plate 10, figure 2. The green hornblende is not fibrous but compact. It appears to have been formed at the expense of the hypersthene by alteration working inward from the edges; that is, by change of the edges of a preéxistent pyroxene body, and not as rims implanted on the edges by outward growth. Magnetite is found in all the silicates as rounded grains. Its outlines are simpler than those generally shown by pyrrhotite. 1922] Hudson: Geology of the Cuyamaca Region of California 199 Quartz norite (no. 114), from point one hundred yards north of contact in northwest quarter of southwest quarter, section 21, township 13 south, range 4 east. The mineral composition is as follows: Labradorite and Bytownite ...... 52% Hypersthene --. 22F Ue. zigeesenee cece eee ee 20% BiOtite mere eee hae 4% Malonetitesee 2 220) sqee Sete 1.3% TE WAGON), Peteree rece yeeros ee 0.4% The average grain is 0.5 mm., the maximum 1.6 mm. The hypersthene and feldspar occur as an aggregate of anhedral grains with curving contacts. The quartz is sometimes molded against crystallographic faces of feldspar, or the two minerals meet along irregular curving boundaries. The biotite occurs as ragged grains and is penetrated along cleavages by the feldspars. It is possible that the biotite represents grains picked up by the norite from the wall rock, granite or schist, and that these grains were never melted or dissolved by the norite. Most of the pyrrhotite occurs as very irregular masses, occupying the space at the meeting place of three or more feldspar individuals. Quartz gabbro (no. 180b), two hundred yards northeast of locality of speci- men 151 in small area of basie rock east of Pine Hills. The mineral composition is as follows: IBM oakeolopenh Wes oes ee eee 31% Tabs qovenysnel aes a sy eles eek eee eee 10% Hornblende .2..-2..----.2 eee 20% Augite Biotite Quartz TNE Woy ae} alt t{ey eee eerie ees eee ee 3% Average grain is 1.0 mm., maximum 2.0 mm. The textural relations of the feldspar, pyroxenes, hornblende, and biotite are quite like those of specimen 114, and need no further comment. ‘The quartz oceurs in irregular veinlike masses, which are optically continuous and may reach 5 mm. in length. Its boundaries against the various inclosing minerals are such as would be produced if the quartz had corroded the pyroxenes or feldspars. The contacts of the quartz against several of the bounding plagio- clase crystals and also against individuals inclosed in the quartz are straight lines. One set of these lines is the trace of the 010 plane of the plagioclase. The other set does not seem to be related to any crystallographic properties of the feldspars, but on the other hand often corresponds exactly with the c axis of the quartz. These quartz masses, together with the bounding and included feldspars, have then the properties of a pegmatitic intergrowth. Effect of marginal chilling.—Norites with distinet porphyritic tex- ture were found at three localities in the north half of section 21, township 13 south, range 4 east. Two of these occurrences are within one hundred yards of the eastern and western margins of the intru- sive mass. They are, however, known to occur as dikes, cutting the even-grained norites. At the third locality the structural relationship 200 University of California Publications in Geology [Vow.18 of the porphyry to the normal norite could not be made out; but, as the locality is situated over three hundred yards from the margin of the basie intrusive, it is probable that this rock also is from a dike. The gabbro on the west flank of Cuyamaca Peak is distinctly porphyritic for a distance of one-quarter mile from its west margin. In no case, however, does the ground mass become as fine in grain as are many of the even-grained rocks from the central portions of the basic intrusive mass. The very width of the zone of porphyritic texture makes it improbable that it is caused by marginal chilling. It is concluded that, for those portions of the intrusive mass mapped as norites and gabbros, there are no marginal chilling effects. The following observations of the average grain of rocks, other than dike rocks, of the norite, gabbro, and closely related types bear out this conclusion: In 6 rocks occurring within 50 yards of the margin, 2 of them immediately at the contact, the average grain was 0.6 mm.; in 8 rocks from Friday Mine it was 0.6 mm., and in 17 rocks, more than one-quarter mile from the margin, including those from Friday Mine, it was 0.56 mm. At two points on the contact of the diorite east of Cuyamaca Peak with the gneissoid quartz diorite, the diorite at the contact is finer grained than that a few feet distant. This de- crease of grain without doubt is due to the cooling effect of the wall rock. Assimilation of wall rock.—F ive specimens of quartz norites and quartz gabbros were collected, representing four or five small areas of these rocks. Three of the specimens were collected from points within 25 yards of the contacts of gabbro or norite against quartz-mica schist. The two other samples were found at distances of 100 and 200 yards from the nearest schist. There can be little doubt that these rocks are ordinary norites and gabbros that have acquired their quartz and biotite from the schist. At the contact of basic diorite against gneissoid quartz diorite, two miles southeast of Cuyamaca Peak, there is con- clusive evidence of the assimilation of wall rock by the basic intrusive. The contact, which is well exposed in the bed of a stream, strikes north 75° west and dips 40° to 60° north. Viewed as a whole, the contact is an even surface, sharply separating the basic rock, which lies above, from the quartz diorite below. The strike of the contact corresponds to that of the gneissoid structure in the quartz diorite, but the latter dips at a steeper angle, 70°, though in the same direction. When viewed in detail, the contact is in places straight and sharp, but in other places the light and dark rocks penetrate one another in complicated fashion. Starting at the contact, the basic rock becomes 1922] Hudson: Geology of the Cuyamaca Region of Califorma 201 gradually coarser till a point about ten feet away is reached, after which there is no change. The light colored rock for an inch or two on the quartz diorite side of the contact is finer grained than is the main mass of the gneissoid rock. The diorite is composed of andesine, augite, biotite, and magnetite. The quartz diorite is made up of quartz, oligoclase, and biotite. » SS Plagioclase w——_—__———“—“_-__-— Brown Hornblende > 16 Harker, A., Petrology for students, 1908, p. 87. 204 University of California Publications in Geology [Vou. 13 The ore minerals, magnetite, pleonaste, and pyrrhotite, are believed to be primary constituents of these rocks. A detailed discussion of the evidence on this point will be given in the chapter on the Friday Mine. Rock alteration—About one-third of the rocks examined contain more or less green hornblende. In many cases this mineral is clearly of secondary origin, formed at the expense of augite or hypersthene. The green hornblende differs in occurrence from the brown variety in that euhedral cross-sections are never seen. The green hornblende is often seen as large, optically continuous, individuals with no rem- nant of the pyroxene from which it is probably derived. Again it occurs in aggregates of smaller individuals, with or without residual masses of pyroxene. In either case the hornblende is charged with magnetite, sometimes as dust, sometimes in irregular masses occupy- ing a coniderable portion of the hornblende body. This magnetite is clearly of secondary origin, a by-product of the alteration of pyroxene to hornblende. Its occurrence, as a dust, is quite different from that of the primary magnetite, such as that described in specimens nos. 124 and 202. The alteration of pyroxene to green hornblende prob- ably involves the addition of no material except water. The source of the water in this region may very well have been the pegmatite intrusions. Some evidence bearing on this point is given in the section on pegmatites. Two specimens from the Cuyamaca basie intrusive mass were found to contain very small amounts of chlorite. A sample of norite from the area of basic rock east of Descanso contains chlorite and calcite. A specimen of olivine gabbro from the north flank of North Peak contains fibrous serpentine developed at the edges of the olivine grains. The only other occurrence of this mineral noted in the district was a minute amount in one specimen from the Friday Mine. The greater part of the areas of basic rocks is mantled by a brown to red soil containing boulders of fresh rock. This soil is sometimes underlain by material which represents an intermediate stage of weathering. It is rock decomposed in place with preservation of tex- ture. Green blotches, representing original hornblende or pyroxene, lie in a light gray or yellow, friable matrix which represents the plagioclase. In such material the boulders of fresh rock, noted above as occurring in the red soil, can be seen in every stage of their formation from joint-bounded blocks. The rounding takes place by decompo- sition of the edges of blocks. No attempt has been made to determine the constituent minerals of the weathered products. 1922] Hudson: Geology of the Cuyamaca Region of Califorma 205 Relation between the different rock types——The complexity with which the different basic rock types are intermingled has been men- tioned in a previous section. These complex relationships not only obtain throughout the main mass of the basic intrusion but also in many of the outlying masses. The small mass, three-quarters of a mile east of Pine Hills, contains typical gabbro and typical norite, both varying in grain from medium to coarse. The larger mass, to the northeast, contains norite, olivine norite, and quartz norite. None of the natural exposures studied exhibit contacts between the different types of basic rocks. Our last resort to obtain evidence on this point is in the underground workings of the Friday Mine. Here it was impossible to find contacts marking off the norites, olivine norites, gabbros, olivine gabbros, augite diorite, brown-hornblende norites, and troctolites from one another. This statement refers to the massive rocks, and does not apply of course to the very fine-grained, brown- hornblende gabbros and brown-hornblende norites which occur in sharply bounded narrow dikes. The hypersthene diorites and augite diorites have a finer grain than that of the general run of the norites and gabbros. Thus the average grain of three rocks from the hypersthene diorite mass is 0.8 mm., that of two rocks from the augite diorite mass is 0.4 mm. The granularity of these rocks is thus less than that of the norites and gabbros of the main intrusive mass, whose average grain is about 0.58 mm. It should be pointed out in this connection, however, that the average grain of four outlying stocks and dikes of gabbro and norite, all being less than one hundred yards in diameter, is 0.5 mm. The cooling effect of schist and granite walls had little, if any, influence on the grain of these rocks. There is no reason to believe that the norite or gabbro which surrounds the hypersthene diorite would have any greater cooling effect. Therefore, it is concluded, the finer grain of the diorites has no bearing on the question of their age with respect to the norites, gabbros, and other rocks of the basic intrusion. It is more likely that fineness of grain varies with the chemical composition of the rock. The main basic intrusive mass, as also the small outlying masses, are intrusive complexes of various basic igneous rocks, the rock types merging one into the other by gradual changes in the proportions of their constituent minerals. Any theory to explain the heterogeneity of the main mass must also account for the variation in the outlying masses. 206 University of California Publications in Geology [Vou. 18 Form and type of intrusion.—The observed localities at which the actual contact of basic rock against the schist or the quartz diorite is laid bare are three in number. At these places the contact plane conforms essentially to the structure of the invaded rock. The map- ping suggests that for perhaps a fifth of the periphery of the basic intrusive mass the contact conforms approximately to the foliation of the gneissoid quartz diorite and schist. However, along the greater portion of the border of the mass the basic rock cuts across the pre- existent structures. In most cases where there is any degree of paral- lelism between the strike of the schist or gneiss and the direction of the contact of the main Cuyamaeca intrusive, the dip of the invaded rocks is toward the intrusive at high angles, varying from sixty or seventy to ninety degrees. There is no evidence of any metamorphism exercised by the basic magma on the schist or quartz diorite. This is to be expected, as the older rocks had a high degree of stability before the invasion of the basic rock. Several small masses of schist occur within the basic intrusive area and two fairly large granite masses were found in the saddle between Cuyamaca and Middle peaks. These occurrences suggest that the basic magma made way for itself, at least in part, by the stoping of wall rock. From evidence presented in a previous section there can be no doubt but that the basic magma enlarged its chamber, to a slight ex- tent at least, by the assimilation of wall rock. It is doubtful if this action was on a considerable scale for the reason that such basic rocks as olivine gabbro and olivine norite are not only found in the central portions of the mass but are rather common along certain stretches of its periphery. A complex intermingling of different rock types was found not only in the main mass of the basic rock but also in several of the smaller outlying masses. No definite contact planes were found be- tween the different types of rock. It seems probable then that the heterogeneity of the Cuyamaca Basic Intrusive is due largely to dif- ferentiation in place. The relatively fine grain of the rocks and the lack of contact action on the wall rocks suggest that the magma solidified at moderate depth. It is believed that the structures of the wall rocks had much their present attitude before the intrusion of the basic masses. The form of the main intrusive body must then be an irregular mass elongated 1922] Hudson: Geology of the Cuyamaca Region of California — 207 north and south and vertically. According to the usage of many geologists, this mass might be termed a laccolith. According to the classification proposed by Daly,’ it would be a chonolith. Age of the intrusion—The Cuyamaea basie igneous mass is younger than the schists and quartz diorite. The evidence for this is: (1) it generally cuts across the structure of schist and quartz diorite; (2) the invaded rocks are schistose, while the intrusive is massive and only exceptionally shows flow banding; (38) dikes, small laccoliths, and plugs of gabbro and norite cut the quartz diorite and schist. It has been shown that the Stonewall quartz diorite is probably of post-Triassic, pre-Cretaceous age. The basic intrusives are thus post-Triassic. It was concluded that the Cuyamaca igneous mass cooled at intermediate depths. If the Cuyamaca area represents the site of an ancient voleano, it might be possible to find remnants of its effusive rocks, which by their relation to sedimentary rocks would give a clue to the age of this intrusion. Voleanic rocks of probable early Tertiary age are exposed in a belt along the western edge of the mountains of San Diego County. Determinations of specimens of these rocks by E. 8. Larsen, quoted in a recent paper by Ellis, class them as quartz latites.* It can hardly be supposed that quartz latites were erupted by a voleano whose eroded neck contains only basic rocks. Andesitic lavas underlie Miocene sediments in Coyote Mountain, in Imperial County.’® No accurate description of these rocks is available. It does not seem at all likely, however, that andesites could have been erupted in any quantity from the hypothetical Cuyamaca voleano. Late Tertiary or Quaternary basalts occur in northwestern San Diego County. These might con- ceivably have come from a ‘‘gabbro-norite voleano,’’ but their recency argues against their assignment to the Cuyamaca igneous period. The question of the exact age of the Cuyamaca intrusive must remain an open one. The writer’s opinion, however, is that the intrusion oc- curred in pre-Cretaceous time, following closely on the development of the quartz diorite batholith. THE RATTLESNAKE GRANITE A mass of granitic rock outcrops in the region of Rattlesnake Valley from five to six miles east of Cuyamaca Peak. Its area is roughly lenticular, with rounded ends. The greatest extent is north- 17 Daly, R. A., Igneous rocks and their origin (New York, 1914), p. 84. 18 Hillis, A. S., U. 8S. Geol. Surv., W. 8S. P., 446, 1919, pp. 72-73. 19 Merrill, F. J. H., op. cit., p. 12. 208 University of California Publications in Geology [Vou 138 south, a distance of three miles. It is a true granite, varying from an alaskite to a biotite-hornblende granite. Orthoclase predominates over plagioclase in all specimens examined. It is coarser in grain than the gneissoid quartz diorite and granodiorite, and is only ex- ceptionally gneissoid. At the south end of the area there is a mar- ginal development of alaskite porphyry. Schist and quartzite inclusions, quite common in the quartz diorite near Rattlesnake Valley, are entirely lacking in the Rattlesnake granite. The contacts of the granite against the schist and gneissoid quartz diorite generally cut across the structure of these rocks. At the north end of the mass the structure seems to indicate that the granite forced the schist apart to make room for itself. The walls of the granite mass dip steeply away from its center in some places, at others the dip is toward the center at somewhat lower angles. Effect of the intrusion on wall rocks.—The contacts of the Rattle- snake granite were studied carefully at but two localities, its northern and southern extremities. At the northern end the granite is intru- sive into fissile quartz-mica schists. The only evidence of metamor- phism is the presence of large muscovite flakes for some distance from the granite, and a small amount of coarse contorted schist at the im- mediate contact. The varying strikes of the schist indicate that the granite made way for itself to some extent by forcing apart the wall rocks. At the southern end of the granite mass, potash-rich granitic material has been injected along the schistose planes. It is evident that the Rattlesnake granite is an injected body of distinctly later age than the gneiss and schist which it intrudes. But its relation in time to the Cuyamaca basic intrusive is indeterminate. Assuming that the date of the two intrusions was essentially the same, the hypothesis is advanced that the gabbro-norite complex and the granite of the Rattlesnake mass are complementary differentiates of a single magma of intermediate composition. The exposed area of the granite is small compared to that of the basic intrusive, but this may have no bearing on the relative volume of the two rocks at the time of their intrusion. It is interesting to note in this connection that the world average chemical composition of quartz diorites, the prevailing igneous rock of this region, is almost the exact mean of the compositions of gabbro-norite and granite. 1922] Hudson: Geology of the Cuyamaca Region of California 209 Basic DiKeEs Dikes of dark, dense, very fine-grained rock eut the various mas- sive basic rocks exposed in the workings of the Friday Mine. Similar dikes cut the massive sulphide ore. All these rocks are brown-horn- blende gabbros and brown-hornblende norites. Their textures differ in no way from that of the coarser, larger masses of the same compo- sition, save in size of grain. All of them carry pyrrhotite in the same manner as the coarser rocks. Dikes of fine-grained norite and norite porphyry were also found at the surface in the neighborhood of the mine. These dikes represent the last activity of the basic intrusion. The fact that they cut the massive sulphide body is evidence of prime importance in the matter of the origin of the ore. PEGMATITE Pegmatite cuts all the rocks of the region. It was not observed in intrusive contact with the massive sulphide body of the Friday Mine, but it does cut the fine-grained dikes which intrude the ore. In an outcrop of gneissoid quartz diorite at the junction of the ereeks in the northwest quarter of section 12, township 13 south, range 3 east, certain narrow pegmatite veins are contorted, though conform- ing to the schistosity of the gneiss. Other veins are perfectly straight and cut across the schistosity. At another locality southeast of the Friday Mine similar facts were observed. There the later veins, the straight ones, carry tourmaline, which is absent from the contorted veins. Sufficient time was not available for further inquiry. The observations suggest, however, that there are two ages of pegmatites, the first related to the quartz diorite intrusion, the second to that of the Rattlesnake granite. The pegmatite occurs as large, irregular lenses, and dikes of all sizes cutting all the older rocks. It is especially abundant in certain portions of the Rattlesnake granite. In the schist it occurs in the forms mentioned above, and also impregnates the schist as a lit par lit injection, in the same manner as granitic material. Petrography of the pegmatites—A specimen of very coarse peg- matite from near the center of a large irregular mass exposed in the lower level of the Friday Mine is composed of quartz, abnormal ortho- clase, microcline, albite-oligoclase, oligoclase, and black tourmaline. A specimen from a six-inch vein in the large schist body on the lower level of the mine is made up of acidie andesine, labradorite, quartz, and tourmaline. 210 University of California Publications in Geology [Vou. 18 A suite of specimens was collected to illustrate the intrusion of gabbro by a narrow pegmatite dike at a locality in the end of the west branch of the north cross-cut, lower level of the Friday Mine. The basic rock near the pegmatite is a partially uralitized augite gabbro. Its plagioclase is labradorite, Ab,, An,,. The basic rock immediately adjacent to the pegmatite is composed of bytownite, green hornblende, and intrusive quartz. There is no augite whatever. The immediately adjacent pegmatite is composed of quartz and andesine feldspar, Ab,-, An,-, while the pegmatite a short distance farther from the con- tact has the same constituents with the addition of a small amount of biotite and labradorite. It is noteworthy that the feldspars of the pegmatite from the center of the large mass include considerable amounts of potash-bearing varie- ties, while the pegmatites of the narrow dikes have only soda-lime feld- spars. This suggests that through material derived from the basic wall rocks a synthetic soda-lime pegmatite has been produced. The tourmaline of the pegmatites examined has a pleochroism of deep steel blue and light blue-gray. The crystals are frequently frac- tured, the cracks being filled by feldspar and quartz. It is clear that the tourmaline was the first constituent to erystallize. It is suggested that the alteration of the pyroxene of the SABES to green hornblende has been brought about by material supplied dur- ing the intrusion of the pegmatite. Water was probably the chief, perhaps the only, chemical agent. It may be that the formation of the green hornblende in all the basie rocks dates from the intrusion of the pegmatites. APLITE A dike of aplite, varying from six to ten feet in thickness, intrudes the schist body southeast and east of Cuyamaca Reservoir. It is con- tinuous for about two miles, its strike conforming essentially to that of the schist. Locally it is offset, for distances of a few inches to a few feet, and at one place it is offset for several hundred feet. These offsets do not appear to be the result of faulting later than the intru- sion of the dike, but seem to result from the fact that the fracture which the dike filled was not continuous. Another aplite dike, with somewhat sinuous outcrop, cuts the quartz diorite gneiss one mile west- northwest of Julian. A microscopic examination of a sample from the first mentioned dike proves it to be a soda aplite, composed of phenocrysts of albite, oligoclase, and quartz in a ground mass of quartz, plagioclase, sericite, 1922] Hudson: Geology of the Cuyamaca Region of California Plat and perhaps a little orthoclase. The quartz and feldspars are set to- gether as a mosaic of mutually interfering grains. The feldspars show no tendency to elongation except to a slight degree in the pheno- erysts. GEOLOGIC STRUCTURE The dominant agencies that have determined the structure of this region are (1) compression and (2) igneous intrusion. Bodies of schistose rocks he within the great mass of quartz diorite in positions determined while the quartz diorite magma was still molten. Without doubt the sediments now represented by the schist series were folded prior to the development of the batholith. The quartzite layers of the schist series, if mapped in detail, would probably furnish the key to this folded structure. Cutting across the fabric of the schist-quartz diorite complex are the two great igneous masses of the Cuyamaca and Rattlesnake intru- sions and smaller masses related to the Cuyamaca Basic Intrusive. The detailed mapping of this region has not shown the existence of any important faults. The ‘‘Preliminary geologic map of San Diego County, California,’’° by A. J. Ellis, shows one major fault zone and two ‘‘lines of topographic expression which suggest the pres- ence of faults’? in the Cuyamaca region. The major fault runs along the southwest flank of Agua Tibia Mountain, determines the south- west boundary of the flat intermountain valley on the Valle de San José grant, determines a line of topographic depression through Ban- ner Canon, passes directly through Banner and thence southeastward. The physiographic evidence for this fault seems good. The writer has nothing to add from his study of the Cuyamaca region. In the area studied this supposed fault is entirely within granite. There is good reason to doubt the existence of the other two faults indicated by Ellis. One of these is supposed to follow the courses of Green Valley and Chariot Canon, leaving that canon so as to pass three- quarters of a mile east of Banner, and continuing on to the north along the western edge of San Felipe Valley. While this fault may exist along the edge of San Felipe Valley, it is surely not present to the south for the reason that a prominent dike in the upper end of Green Valley crosses the supposed fault without offset. The physiographic features that probably led to the mapping of the third fault, in the region west of the Cuyamaca Mountains, can be explained as due to differential erosion. 20U. 8S. G. S., Water Supply Paper 446, pl. 3. 212 Umversity of California Publications in Geology [Vou. 13 Minor faulting, like that seen in the Friday Mine and described in the chapter on that mine, is probably widespread throughout the region. THE FRIDAY MINE ORE BODY The Friday Mine is situated immediately south of the road between Cuyamaca Reservoir and Julian, at a point four miles southeast of that town. It lies half a mile southwest of the divide between drain- age to the Pacific Ocean and that to the Colorado Desert. The eleva- tion at the mine is about 4700 feet above sea level. It is situated in an embayment of the main area of the Cuyamaca Basie Intrusive. DiIscOVERY AND DEVELOPMENT The original location of the Friday claim was made on an outcrop of gossan lying 55 feet northwest of the shaft now in use. The shaft there sunk was abandoned, apparently because ore was not found, and a new one started in gabbroie rock. At 50 feet depth it entered a body of schist which dips south at an angle of 75°. At 127 feet depth the lower side of the schist body was reached and a drift was run to the northeast along the contact of schist and basic intrusive rock. The drift entered sulphide ore at 50 feet from the shaft and was continued to the northeast, reaching the southwest or footwall side of the ore body at a point 85 feet from the shaft. From this point the footwall of the ore body was followed for 20 feet, and then a north- west crosscut was driven to the northern limit of ore, where a winze was sunk 16 feet on the contact. A working to the northeast from the junction of crosscut and main drift failed to find any ore. Ata later date an incline was put down from the bottom of the shaft, along the schist body, to a point 45 feet measured vertically below the first level. Drifting along the footwall of the schist on this lower level failed to disclose any ore. After considerable blind work the down- ward continuation of the ore was found, as a thin wedge, almost im- mediately beneath the winze on the upper level. GENERAL GEOLOGIC DESCRIPTION The underground workings of the Friday Mine penetrate five dis- tinct formations, the most abundant being the Cuyamaca Basic In- trusive, which here is predominantly a norite, but includes gabbro and peridotite facies. Included in the basic rock are several bodies 1922] Hudson: Geology of the Cuyamaca Region of California 218 of schist, which differ in no way from the typical rock of the Julian schist series. A body of massive sulphide ore lies, for the most part, entirely within the igneous rock, but on the upper level of the mine it is also in contact with the schist. Narrow dikes of fine-grained, horn- blende-gabbro and hornblende-norite cut both the massive gabbroic rock and the sulphide ore body. Pegmatite occurs as large irregular bodies and dikes of various thicknesses, which eut not only the massive gabbroie rock but also the dikes of fine-grained basic rock. The rocks of the mine.—The main body of schist is a tabular mass, striking northeast and dipping south at an angle of 75°. Along the upper level it has a fairly uniform thickness of 12 feet, but in the lower level its width varies from 1 to 12 feet. This rock differs in no way petrographically from the quartz-mica schist of the main Julian schist body, and is assigned to that formation. The contacts of the schist against the inclosing igneous rock are smooth planes along which a small amount of gouge is developed. That the schist body owes its present position essentially to faulting is, however, doubtful. Some movement along contacts is to be expected where two rocks of such dissimilar physical properties as schist and norite meet. The schist bodies are thought to be fragments torn from some larger body of the same rock by the basic intrusive magma. The Cuyamaca Basic Intrusive is represented in the Friday Mine by norites, gabbros, olivine gabbros, olivine norites, brown-hornblende gabbros, peridotites, troctolites, and augite diorite. Norite is by far the most abundant of these types, making up at least one-half of the mass of basic rock exposed here. Peridotite and troctolite are quite rare, as is also augite diorite. With the exception of the augite diorite all the rocks earry pyrrhotite, the amount varying from a trace up to 3.0 per cent. Magnetite is rare. These rocks differ in no way from the basic rocks found elsewhere within the mass of the Cuyamaca basic intrusive. The massive ore body.—The ore body is an irregular mass the greatest horizontal section of which probably lies between the two levels of the mine. On the upper level its greatest measurement is along a north-south line, a distance of forty feet. The width here varies from five to twenty-five feet. On the lower level the ore body is twelve feet long and only a few feet wide and wedges out before reaching the floor of the working. The ore consists of sulphides, of which pyrrhotite and chalcopyrite may be distinguished with the unaided eye, together with various 214 University of California Publications in Geology (Vou. 138 silicate minerals. Above the upper level the ore has been completely oxidized, the residue consisting of limonite and. the silicate minerals of the gangue. In a zone along the contact between completely oxi- dized and partially oxidized ore, sulphates and arsenates of nickel and cobalt are present, including erythrite (hydrous cobalt arsenate, ‘‘eobalt bloom’’) and morenosite (hydrous nickel sulphate). Below the completely oxidized material on the upper level the sulphides have been decomposed along fracture planes and there is a slight amount of oxidation even in the ore of the lower level. North peak Vie (ANC ee NS Ve Oe NNR eS Se ne ee ae Se ZGRAIN - tS N ~ Nes ae <= eG / / / gee F x / * - y Nap i DTD, \— TNorite)// \, EF PANS / 127 ft.level ri - / (eee a ae Nn Noa a / ie \ A wares \ Uy rer aes = == UP Sap NX RM Nie US oe Fig. 2. Vertical section through the Friday Mine ore body. Scale: 1 inch=30 feet. Basic dikes.—Narrow dikes of fine-grained hornblende gabbro and hornblende norite cut the massive gabbroie rocks at several localities. Near the bottom of the winze on the upper level one of these dikes euts the sulphide ore. All the dikes show marked similarity among them- selves, both in mineral composition and grain. They probably repre- sent a late stage of the activity of the Cuyamaca Basic Intrusive magma. The fact that the ore is cut by a dike of this type is evidence of a close relationship between ore formation and magmatic processes. Pegmatite—A narrow dike of pegmatite cuts gabbroic rock 77 feet east of the shaft on the upper level. On the lower level the pegma- tite is much more abundant. It occurs as narrow dikes cutting the basic igneous rocks at several places, and also as a large irregular mass, cutting both norite and schist, at a point near the junction of the east-west drift and the north cross-cut. At the latter place the pegmatite is particularly coarse, carrying feldspars several inches in diameter and tourmalines up to 6 inches in length. The pegmatite 1922] Hudson: Geology of the Cuyamaca Region of Califorma 215 found particularly easy entrance along the contacts between the schist and basie intrusive and also along planes of schistosity within the schist. Much of the schist on the lower level is so saturated with pegmatitic material that it may be called injection gneiss. Calkins has reported that the massive ore body ‘‘is eut by a thin dike of pegmatite containing conspicuous erystals of common black tourmaline.’’??~ The writer was unable to find the locality at which this phenomenon was observed, and believes that the ore has been stoped out there. However, pegmatite was seen cutting a dike of the fine-grained brown-hornblende norite. As these basic dikes are known to be younger than the ore, the later age of the pegmatite also is estab- lished, and Calkins’ observation confirmed indirectly. The boundaries of the ore-—With the exception of one boundary plane exposed on the upper level where the ore body is in contact with schist, the sulphide body is completely inclosed in the rocks of the basic intrusive mass. The shape of the ore body (see fig. 2) indicates that the contact between ore and schist is a fault. This contact is a smooth plane along which a small amount of limonite-stained gouge has been developed. Most of the contacts between ore and gabbroie rock are sheared, but a portion of the southern boundary plane, ex- posed in the upper level of the mine, is not affected by shearing and shows a gradation between coarsely crystalline pyrrhotite, carrying relatively small amounts of silicate minerals, and norite, carrying dis- seminated particles of sulphides which differ in no way from the sulphides found in the basic rocks in other parts of the Cuyamaca region. MINERALS OF THE MASSIVE ORE Pyrrhotite——This is the predominant mineral of the ore body. It occurs in individuals without crystal outline, but with well developed parting planes. The extent of these planes shows that the pyrrhotite is coarsely crystalline, some individuals being over one and a half inches in diameter; but the average is less than one-half inch. The parting planes show a dull gray color, but fresh surfaces obtained by breaking the mineral across the parting have a conchoidal fracture and a metallic white to bronze color. In polished surfaces of the ore the pyrrhotite is readily determined from its prominent basal parting, as shown in plate 10, figures 5 and 6, and plate 118, figure 1, and its pinkish color. Magnetite—Huhedral octahedrons of magnetite are found imbedded in the pyrrhotite. Chalcopyrite.—Grains of chalcopyrite up to one-eighth inch in diameter may be seen. It also occurs in smaller grains and minute veinlike masses. On pol- ished surfaces chalcopyrite is identified by its brilliant luster, freedom from cracks and cleavages, and its characteristic yellow color. 21 Calkins, F. C., U.S. Geol. Surv., Bull. 640, 1916, p. 81. 216 University of California Publications in Geology [Vow.13 Polydymite.—The nickel-bearing mineral of the massive ore can be seen only on polished surfaces. It is white in color, takes a fair polish, and is 5.0 to 5.5 in hardness. This mineral has good cleavages in three directions, which have been interpreted as cubic. See plate 10, figures 5 and 6. Following are the results of michochemical tests of this mineral: HNO, dilute—slight, dull brown stain, rubs to clean smooth surface. HNO, cone.—strong effervescence, dark brown stain. Rubs to gray rough- ened surface. HCl, both dilute and concentrated—acid turns yellow. Aq Reg.—strong effervescence, light brown stain, rubs clean. Acid turns green. FeCl,—no effect. NH,OH—no effect. KCN—slight brown stain, rubs clean. This mineral does not correspond exactly in its chemical reactions to any of the minerals listed in Murdoch’s tables.22. Chloanthite, gersdorfite, and polydymite are suggested by the determinative tables, the description of gers- dorfite perhaps corresponding closest to the Friday Mine mineral. However, blowpipe analysis of isolated fragments of the pure mineral and also of the whole ore show no trace of arsenic, giving strong tests for nickel and sulphur, with no cobalt. It is concluded that this mineral is either polydymite or a closely allied and hitherto undescribed species. Brown Hornblende.—This mineral, differing in no way in optical properties from that found in the gabbros and norites, is to be found in samples of the least altered ore. It occurs in euhedral and subhedral forms, ineclosed within single pyrrhotite crystals or in the spaces at the meeting point of several crystals. The brown hornblende of the ore has a much greater tendency toward euhedral outline than does that of the norites and gabbros. This is well shown in plate 10, figures 3 and 4. Compact Green Hornblende—This mineral is much like the brown variety in its mode of occurrence. It is pleochroic in green and blue-green colors. Augite.—A small amount of colorless pyroxene with positive sign was iden- tified in the ore from the lower mine level. Some of the more altered ore from the upper level shows under the microscope six and eight sided masses com- posed of granular calcite. These are thought to be pseudomorphs of the car- bonate after augite. Chlorite.——Green clinochlore occurs in greater or lesser amount in all the ore. It is found replacing the hornblende and also as minute veinlets traversing both the silicates and ore minerals. Plate 10, figure 3 illustrates the partial replace- ment of brown hornblende by chlorite. An inspection of thin sections and polished surfaces leaves no doubt that the chlorite in both its modes of occurrence was introduced at a distinctly later time than that of the formation of the sulphides and hornblende. In the com- pletely oxidized gossan the chlorite is found in hexagonal tablets with good crystalline outline. These may attain a diameter of one-half inch. In the partially oxidized ore chlorite occurs in a similar way, but in the fresh ore it is found only in small individuals replacing the hornblende and in the minute vein- lets cutting the ore minerals. This evidence suggests that the chloritic type of 22 Murdoch, Joseph, Microscopical determination of the opaque minerals (New York, 1916). 1922] Hudson: Geology of the Cuyamaca Region of California 217 alteration was effected by meteoric waters and that the place favorable for the growth of chlorite was in the sulphide ore not far beneath the oxidized zone. Actinolite——The partially oxidized ore contains a considerable amount of a fibrous, green amphibole. Its optical properties are: e/\¢—19°, optical sign, negative. a=1.62+, B—1.630, y—1.647. Colorless in thin section. This is probably actinolite, though its indices of refraction are higher than those listed in the tables. It is closely associated with the chlorite, flakes of the latter mineral being inclosed in the amphibole. In the completely oxidized ore the actinolite is white and dull, probably the result of leaching. It is thought that the actinolite is a secondary mineral formed by the same agencies as was the chlorite, since it increases in amount as the degree of oxidation increases, and is known to form at the expense of brown hornblende. (See pl. 10, fig. 3.) Calcite-—White carbonate, identified as calcite, occurs as minute veinlets traversing both sulphides and silicates. The relation of the calcite to the horn- blende in some specimens suggests that it may replace that mineral (see fig. 18) and certain masses of granular calcite are interpreted as complete replacements of amphiboles and augite by the carbonate. INTERRELATIONS OF MINERALS If the calcite masses which show six and eight sided sections are correctly interpreted as pseudomorphs after augite, it follows that the augite possessed idiomorphie outlines. The compact green hornblende generally occurs in stout prisms with rounded terminations. It ap- proaches closer to euhedral form than does the amphibole of the norites and gabbros. The brown hornblende is found sometimes in even more perfect crystals. In general it may be said that the primary silicates usually have several of their bounding planes determined by erystal- lographie faces, the other bounding planes being smooth curves. There is little tendency for the hornblendes to be penetrated along their cleavages by the sulphides. The sulphides make up from 75 to 90 per cent of the ore. As pyrrhotite is the prevalent sulphide, it may be said that this mineral determines the texture of the ore. It oceurs in grains rang- ing from a few millimeters to, several centimeters in diameter. In either the polished surface or the hand specimen the grains may be distinguished one from the other by the diverse orientation of the basal partings in the different grains. The boundaries are never erystallographie planes, but are made up of smooth eurves, much like the boundaries between the silicate minerals of the gabbros and the norites. The texture of the ore further resembles that of the gabbros and norites in that the grains of pyrrhotite are on the whole equant. Chaleopyrite is found in general as small irregular masses oceu- pying the space where several large grains of pyrrhotite meet. Its 218 Umversity of California Publications in Geology [Vou.13 contacts against the pyrrhotite are smooth, clean-cut curves. It some- times occurs in somewhat elongated masses, which might be interpreted as veins, but the chaleopyrite shows no tendency to follow the parting of the pyrrhotite; and the highest magnification fails to show com- municating channels between adjacent chaleopyrite masses. The polydymite (?) is frequently intimately associated with the chalcopyrite and has much the same textural relations to the pyrrho- tite as has the chalcopyrite. It is found in equant grains with rounded outlines and as irregular masses which may send off several branching apophyses between the adjacent pyrrhotite grains. These apophyses terminate as blunt wedges. They do not in all eases confine them- selves to the space between two pyrrhotite grains, but extend into single individuals of pyrrhotite, in no case, however, showing any tendency to follow the parting planes. In one ease the parting planes were seen to curve on approaching one of the apophyses of polydy- mite (?). The examination of numerous polished surfaces failed to show a single case where either polydymite (?) or chaleopyrite occurred with- out pyrrhotite. Furthermore, masses of the nickel or copper mineral, that might be interpreted as veins cutting the pyrrhotite, stop ab- ruptly on reaching the bounding planes between silicates and sulphides. This relation is shown in plate 11, figure 1. In some instances it appears as though the chalcopyrite had been mobile after the poly- dymite had ceased to form. In other instances the reverse relation is shown. It is probable that the copper and nickel minerals were formed at very nearly the same time. Both chalcopyrite and poly- dymite (?) were apparently mobile after the solidification of the pyrrhotite. THE DISSEMINATED SULPHIDES OF THE CuyAMAca Basic INTRUSION A study of thin sections showed that the pyrrhotite occurs in two ways, (1) as irregular grains occupying the space where several silicate individuals meet, (2) as grains with simple oval or circular section, entirely inclosed in single silicate crystals (pl. 11, fig. 2). The most irregularly bounded grains of pyrrhotite are no more complex in their outline than are many augite and brown hornblende grains. While in some of the rocks examined the pyrrhotite occurs for the most part in association with the ferromagnesian minerals, yet in none of the rocks is it restricted to this position and in many of them ,the pyrrhotite shows no preference for any one silicate species. 1922] Hudson: Geology of the Cuyamaca Region of Californa 219 A study of polished surfaces of norites and gabbros has modified only slightly the ideas as to textural relationships gained from the study of thin sections, excepting that it was found that the pyrrho- tite occasionally occurs in veinlike masses, as illustrated in plate 11, figures 3 and 4. As such minute veinlets of sulphide were found at only two places in the nine polished surfaces studied, this phenomenon must be considered exceptional. The typical textural relations of ores to silicates in the basic rocks are shown by plate 11, figures 5 and 6, and plate 12, figures 1-5. Pyrrhotite is readily identified in hand specimens of the rocks by its white to bronzy color, high metallic luster, and econchoidal fracture. In the polished surfaces it appears white to pinkish and the traces of parting planes permit it to be readily distinguished from the other sulphides. Chaleopyrite sometimes occurs in large enough masses to be made out by the hand lens, but the greater amount is found in such minute individuals that the examination of polished surfaces with the micro- scope is necessary to differentiate it from the pyrrhotite in which it is invariably imbedded. A white mineral, with hardness intermediate between pyrrhotite and chaleopyrite, is found in many of the rocks. It takes a high polish, shows no cleavage or crystal outlines. Michrochemical tests made of this mineral are as follows: HNO, dilute—rich yellow-brown stain, no effervescence. Rubs off readily to untarnished surface. HNO, cone.—similar action, but slight brownish stain persists after consider- able rubbing. HCl, both dilute and cone.—no effect. Aq Reg.—no effect. Samples of pentlandite from Sudbury gave similar reactions, but differ from the Cuyamaca mineral in having a yellow color in com- parison with pyrrhotite. Enough material for blowpipe analysis or quantitative tests could not be isolated, but the evidence given above seems enough to justify the conclusion that the mineral is either pent- landite or else some very closely allied species. Relationships between the sulphide minerals.—The pentlandite and chalcopyrite never occur except as portions of a compound grain with pyrrhotite. No matter what the shape of the pentlandite or chaleopy- rite grain imbedded in the pyrrhotite may be, the exterior boundary of the whole sulphide mass is always made up of smooth curves, differ- ing in no way from the boundaries of pyrrhotite grains that carry no 220 University of Califorma Publications in Geology [Vou.18 nickel or copper. The chalcopyrite and pentlandite generally occur in one of three ways: (1) as grains, whose contacts against the pyr- rhotite are irregular, sometimes serrated, curves; (2) as regular forms which show on the polished surfaces as lath sections with blunt ends; or (3) as forms which show as narrow wedges on the polished surfaces. The last two may be expressions of essentially the same form. There are no veins of pentlandite or chalcopyrite in the pyrrho- tite and there is no relation whatever of the nickel and copper minerals to the parting planes of the pyrrhotite. The pentlandite and chal- copyrite often occur together and then may form a compound grain with a common exterior boundary against the pyrrhotite, similar to the boundary of a compound grain of the three sulphides against the silicates. Almost invariably the nickel and copper minerals are found at the edge of pyrrhotite grains. An exception to the rule are minute tufts of pentlandite which were found in one specimen along a vein- let of calcite within the pyrrhotite. As the calcite is known to be secondary, these tufts are thought to be secondary pentlandite. As a further proof that the nickel mineral occurs only in pyrrhotite the results of a series of qualitative tests for nickel with dimethyl- elyoxime may be cited. Three basic rocks that were known to contain no pyrrhotite did not carry enough nickel to give the faintest reaction with this delicate test. On the other hand, some of the pyrrhotite- bearing rocks, including three from the immediate vicinity of the ore body, do not carry nickel, showing that some of the pyrrhotite is not nickeliferous. Relation of sulphides to rock altcration—Chlorite is of rare oceur- rence, but in those few specimens in which it was identified it is clearly of later age than the ore minerals. Secondary green hornblende is much more common than chlorite. The textural relations show that to a large extent at least it also is later than the sulphides. As further evidence of this the following statistics may be cited: Of 9 gabbros with green hornblende, 6 carry pyrrhotite, 3 have no pyrrhotite. Of 16 gabbros, both with and without green horn- blende, including the 9 rocks above, 11 carry pyrrhotite, 5 have no pyrrhotite. The ratio of gabbros carrying sulphides to those without sulphides is the same for all gabbros as for those carrying green horn- blende. Furthermore, none of the gabbros and norites with over 1 per cent sulphide was found to contain any green hornblende. Relation of sulphides to total composition of rocks—All of the rocks of the Cuyamaca Basic Intrusion carry either magnetite or pyrrhotite. Some of the rocks carry both ore minerals; but in general 1922] Hudson: Geology of the Cuyamaca Region of California Zot it may be said that a rock with considerable pyrrhotite will have little or no magnetite, and those rocks with considerable magnetite will have little or no pyrrhotite. There thus seems to be some kind of a recip- rocal relationship between the two minerals. The most basic rocks are those in which the disseminated sulphides are most likely to be found. As most of these basic rocks carry either augite or hypers- thene, it might be thought that the presence of these pyroxenes favored ee < 9% 4 (tg. P 7O Niainber OF samples With no PYITHOT PE, Foto of LXE A Samples Carry tr y I rr Oooo SS Ab, Ab Absy 120 75 Abyss Ab, An, Anas As Anns Aino 70 [ate poligoclase] Anaesire| Labrador te |By town 7 VOEr Fig. 3. Graph showing relationship between (1) the chances of finding pyr- rhotite in the various rocks of the Cuyamaea Basie Intrusion, and (2) the kind of plagioclase characterizing the various rocks. the development of the sulphides. This, however, is not the case, as none of the hypersthene diorites or augite diorites carries any pyrrho- tite. The kind of plagioclase is the determining factor for the presence or absence of pyrrhotite. The more basic the plagioclase the more likely is the rock to carry pyrrhotite. As the feldspar generally makes up well over half the rock, it may be said that the presence of pyrrho- tite is conditioned by the total composition of the rock. Figure 3 is 222 University of California Publications in Geology [Vow.18 a curve representing the chances of finding pyrrhotite in the gabbros, norites, diorites, ete., that are characterized by the different feldspars of the soda-lime series. It is plotted from the results of study of 82 specimens that are thought to represent fairly well the total compo- sition of the Cuyamaca Basic Intrusive mass. Dike rocks are excluded. LABRADORI TE a, ff PYRRHOTI TE ne 0 Qe a SSeS Be) LABRADORI TE -BYTOWNI TE % / ° PYRRHOTI TE ae 0 Po % g (o) P 2 BYTOWNITE PYRRHOTITE > if fe) oO 7: {e) 6 Ss g ; MAGNETITE ~ . : ANDESINE, OLIGOCLASE 10 20 30 Fo 50 60 70 €0 9390 SUM OF PERCENTS OF FERROMAGNESIAN MINERALS Fig. 4. Graphs showing the relation existing between the amount of ore minerals and the amount of ferro-magnesian minerals, in rocks of the Cuyamaca Basic Intrusion characterized by four different plagioclase feldspars. Within each set of rocks characterized by a single type of plagio- clase there is a rough direct relationship between the amount of ore minerals and the sum of the amounts of the ferromagnesian silicates. Figure 4 shows this relationship. The sum of the ferromagnesian minerals for each rock was obtained by the addition of the products 1922] Hudson: Geology of the Cuyamaca Region of Califorma — 223 of the percentage of each mineral by an appropriate factor, the factors being chosen to bring the percentage of each mineral to the same pro- portion with respect to (MgO, FeO)SiO,. The factors are: olivine, 1.4; hypersthene, 1.0; augite, 0.5; green hornblende, 0.5; brown horn- blende, 0.66. The curves for the labradorite-bytownite and bytownite rocks show a direct proportion between the amount of sulphide and the sum of the amounts of ferromagnesian minerals. The eurve for magnerire cd >b rhotite (har n o More pyr 8 82 xe" & Woe * S x es ye x LS Va $4 ce) o g iS 0 | : Granks Characterizing e ii Ae ldspors : == Lab, Andes ie, Ss ‘ —0 Apa Lab, Andesie 7 ceeseepeneee eee x Labragorite. Per cent of pyrrhotite ranus percent of magnetite. ----- Labradorite - Bytownite ——aA Bytownte 10 20 30 4O 5O 60 70 60 30 Sum of ferromagnestan mipetals. Fig. 5. The four curves represent the relations between the ores and the ferromagnesian silicates for four different groups of the basic intrusive rocks, characterized by four different plagioclase feldspars. The sum of the ferro- magnesian minerals for each rock was obtained by addition of the products of the percentage of each mineral in the rock by an appropriate factor. These factors were used so as to make the various sums proportioned with respect to (MgO, FeO)SiO,. These factors are: olivine, 1.4; hypersthene, 1.0; augite, 0.5; green hornblende, 0.5; brown hornblende, 0.66. the labradorite rocks is without character and proves nothing. The eurve for the soda-rich plagioclase rocks suggests a relationship be- tween the amount of magnetite and that of the ferromagnesian min- erals, but not enough samples of these rocks were examined to make this a good ease. The recognition of a reciprocal relationship between the amount of pyrrhotite and the amount of magnetite in the basic rocks has led to the idea of plotting the quotient of magnetite by pyrrhotite against 224 University of California Publications in Geology [Vou.138 various figures representative of the composition of the silicate portions of the rocks. The graphs obtained were extremely irregular and seemed to condemn the theory. Later it was discovered that by plot- ting the difference between the percentages of pyrrhotite and magne- tite against the sum of the ferromagnesian minerals irregular graphs could be obtained, which when ‘‘averaged’’ became smooth curves. These curves (fig. 5) show that the difference between the amount of sulphides and that of magnetite, in rocks characterized by any particular plagioclase, stands in direct ratio with the sum of the per cents of the ferromagnesian minerals. The origin of the disseminated sulphides—From the standpoint of the textural relations of the three sulphides, considered as a unit, toward the silicate minerals which inclose them, it is almost incon- celvable that the pyrrhotite, with its attendant nickel and copper min- erals, could have been introduced into the rocks after the consolidation of the silicates. The reasons for this conclusion are: (1) lack of veins; (2) sulphides do not oceur along cleavages of silicates; (3) contrast between the simple spherical or ovoid grains inclosed in single siheate crystals and the irregular grains with ramifying apophyses that occur at the meeting place of several silicate crystals; (4) irreg- ular grains are no more complex in outline than many of the brown hornblende and augite individuals; (5) the sulphides do not replace the silicates. This is shown by (a) textural relations, (b) lack of preference for association of sulphides with any one silicate or group of silicates, and (c) the occurrence of sulphides bears no relationship to rock alteration. With the exception of the minute tufts of pentlandite which were found along calcite veinlets within the pyrrhotite, the pentlandite and chaleopyrite could not have been introduced from without after the solidification of the pyrrhotite. This is shown by: (1) the absence of veins of pentlandite or chalcopyrite in either silicates or pyrrhotite; (2) the independence of particles of pentlandite or chaleopyrite of the parting planes of the pyrrhotite; (3) occurrence of nickel or copper mineral only as a part of a compound grain with pyrrhotite. Conclusions.—The sulphide minerals are essential constituents of the igneous rocks in which they are found. The lack of crystalline outlines on the part of the pyrrhotite and the ramifying apophyses of the more irregular individuals show that the sulphide was the last constituent of the rock to solidify. The simple, round forms of those pyrrhotite grains that are inclosed in single erystals of silicates are 1922] Hudson: Geology of the Cuyamaca Region of Califorma — 225 also taken as proof that the sulphides existed as drops of liquid during the crystallization of the silicates which now inclose them. There is a lack of evidence as to the relative time of formation of the three sulphides. They perhaps solidified simultaneously in their present form, or, what is more likely, by analogy with certain metal- lurgical products,?* we may conceive of the sulphides solidifying as a homogeneous matte, which later became unstable, due to decrease of temperature, pressure, or both, and broke down to the mixture of three minerals as we now see them. RELATION OF THE MASSIVE ORE Bopy To THE ENcLosING Rocks The average composition of the Cuyamaea Basie Intrusion, leav- ing out of account the rocks of the Friday Mine, is approximately that of a gabbro-norite, whose plagioclase is a labradorite, carrying 38 per cent albite molecule. If, further, the diorites are eliminated from the ecaleulation, for the reason that they may represent later intrusions and not differentiates in place, the approximate average composition of the mass is that of a gabbro-norite with a labradorite- bytownite (29 per cent albite molecule) as its feldspar. The average rock of the Friday Mine is an olivine norite, whose feldspar is by- townite (24 per cent albite molecule). It is evident, then, that the rocks adjacent to the massive ore body are more basic than is the average of the rocks from other portions of the intrusive mass. Of eighteen basic rocks collected from the Friday Mine workings, only one, an augite diorite, lacks pyrrhotite. More than one-third of the rocks from other localities, excepting the rocks of the two diorite areas, carry no sulphide. Furthermore, the average sulphide content of the rocks of the Friday Mine, excepting those in immediate prox- imity to the ore body, is 1.1 per cent, while the average for the basic rocks from other localities, leaving out of account those which earry no pyrrhotite whatever, is only 0.7 per cent. It is seen, then, that with the increase in basicity of the igneous rocks in the vicinity of the ore body there is also an increase in sulphide content. The relations set forth above would lead one to expect gradational contacts between the massive ore and the norite. As has been noted before, the greater part of this contact is determined by slip planes; but at one point an unslipped contact is preserved. Here the trans- ition from norite, carrying a few per cent of sulphides, to ore carrying over 50 per cent of sulphides takes place within a distance of less than one centimeter. ; 23 See pp. 240-241. 226 University of California Publications in Geology (Vou. 18 It is easy to understand how such a narrow transition zone could be erased by slight slipping, and the conclusion, based on lack of gouge, that the bounding slip planes of the ore body were the result of only minor movement, is confirmed. Detailed description of gradational contact—The following obser- vations are based on the examination of a suite of thin sections of the different stages of the transition zone, and of a polished surface ent so as to show several centimeters on either side of the contact. The norite from 1.5 to 2.0 em. from the contact is an olivine norite with hypersthene, monoclinic pyroxene, and brown hornblende. The plagioclase is labradorite-bytownite. Some spinel and pyrrhotite, pent- landite, and chalcopyrite are present. The rock at 0.5 to 1.5 em. from contact is similar to the above except that the feldspar is anorthite. Sulphides occur in consider- able amount, probably 5 per cent of the whole mass. The textural relations of the pyrrhotite to the silicates is no different from those seen in all norites. Rounded grains of pyrrhotite within fresh hypers- thene crystals are particularly abundant. On approaching closer to the contact the spinel and sulphides increase in amount. The brown- hornblende also becomes more abundant while the hypersthene seems to remain constant in amount and the feldspar decreases. A few millimeters from the contact a large angular mass of pyrrhotite, con- taining chalcopyrite and polydymite (?), was noted within fresh sili- cates. The actual contact is an extremely irregular surface along which the ore and norite penetrate one another for distances up to 1 cm. from a median plane. The ore adjacent to the contact consists of pyrrhotite, polydymite (?), and chalcopyrite with bluish-green hornblende in somewhat rounded prisms and confused aggregates of actinolite. A small amount of calcite is found in minute veinlets and in pseudomorphs after primary minerals. Two minute rounded masses of a bright yellow substance, identified as serpentine, were found in one of the thin sections. The ore adjacent to the norite is no different from that found in other portions of the ore body, with one exception. There is a yellow- ish material of high metallic luster that bears the same textural re- lations to both silicates and polydymite (?) and chalcopyrite as does the pyrrhotite. It shows a peculiar concentric banding which seems related to tiny veinlets of calcite which penetrate the ore. Micro- chemical tests did not establish the identity of this material, except to show the presence of irregular patches of pyrrhotite within its 1922] Hudson: Geology of the Cuyamaca Region of California 224 gy g mass. The tests, however, are suggestive of mareasite and the material is probably then a partial replacement of pyrrhotite by that mineral. ORIGIN OF THE MASSIVE ORE The close genetic relationship of the massive ore body to the norite is shown by the following facts: (1) The primary gangue minerals of the ore are ferromagnesian silicates commonly found in the norite. (2) The ore minerals of the massive ore body are the same as those found as disseminated particles in the norite, save that polydy- mite (?) oecurs in place of pentlandite. (3) The ore was formed before the cessation of activity of the basic magma. This is shown by the fact that dikes of pyrrhotite- bearing, hornblende norite, cut not only the massive norite but also the ore body. The rock of these dikes is no different from the ordinary norite save that it is finer grained. That the ore was not introduced from without after the solidi- fication of the rocks which now inelose it is shown by (1) lack of either large or small scale veins of sulphides in the norite, (2) grada- tional contact between ore body and norite, (3) lack of replacement of the silicate by ore minerals. The massive ore body is thought to have accumulated as an ultra basic differentiate of the norite magma, before or during the consoli- dation of the norite which now forms its walls, for the following reasons: (1) The molten norite was a competent source, as the norite now carries disseminated sulphides which were normal constituents of the magma. (2) The rock surrounding the ore body is more basic as regards its silicate constitution than is the whole mass of the Cuyamaca Basie Intrusion, and its content of sulphides is greater than is that of the whole mass. If differentiation from a gabbro-norite with labradorite- bytownite feldspar, and 0.7 per cent sulphides, to an olivine norite, with bytownite feldspar and 1.1 per cent sulphides, ean take place, there is every reason to suppose that further action could produce a rock made up of pyrrhotite, nickel and copper sulphides, hornblende, and augite. It was shown, in the ease of the disseminated ore particles in norite, that the sulphides were probably still in liquid condition after the solidification of the silicate minerals. It is probable that this 228 University of California Publications in Geology (Vou. 18 condition also obtained in the massive ore. While the polydymite (?) and chaleopyrite of the ore body show some tendency to occur in vein- like forms, such veins are not nearly so well marked as are those in nickeliferous pyrrhotite from other districts. The occurrence of these veins has been used by several investigators as proof that the nickel and copper minerals were introduced from without after the solidi- fication of the pyrrhotite. That such is not the case in the Friday Mine deposit is shown by the following observations: (1) The polydymite (?) and chaleopyrite are found only in pyr- rhotite. When a ‘‘vein’’ of one of the former minerals reaches a silicate mineral it stops abruptly. This is well shown in plate 9, figure 3. (2) Certain rocks immediately adjacent to the ore body carry no trace of nickel, although they do earry considerable pyrrhotite. A dike of hornblende norite that cuts the ore body earries nearly 1 per cent of pyrrhotite, but shows not a trace of nickel with the most deheate tests. THEORIES OF ORIGIN OF NICKELIFEROUS PYRRHOTITE Deposits of nickehferous pyrrhotite occurring in intimate associ- ation with basic igneous rocks are of world-wide distribution. The marked similarity both mineralogical and geological between the dif- ferent deposits suggests that all have been formed by essentially similar processes. The geologic literature descriptive of these deposits is voluminous and the theories advanced as to their origin are varied. The writer will not attempt to summarize the literature on this subject, as ex- cellent summaries have already appeared in the works of Tolman and Rogers** and of the Royal Ontario Nickel Commission.?° A_ brief statement will be made, however, of the various theories advanced for the origin of these ores. Since 1891 a controversy has been waged as to whether the nickel- iferous pyrrhotite deposits are of a magmatic or non-magmatie origin. Up to a recent date the term magmatic has been applied to those deposits in which the ore minerals are conceived to have been essential constituents of the igneous magmas which consolidated to form the country rock of the deposits, the segregation of the ore minerals, into masses more or less free from silicate minerals, taking place before 24 Tolman, C. F., Jr., and Rogers, A. F., A study of the magmatic sulfid ores, Leland Stanford Junior University Publications, 1916, pp. 23-55. 25 Royal Ontario Nickel Commission, Toronto, Report, 1917, pp. 95-286. 1922] Hudson: Geology of the Cuyamaca Region of California 229 or during the solidification of the magma. The proponents of the non-magmatic theories conceive of the introduction of the sulphide minerals into the igneous rock, after its consolidation, by either hydro- thermal or contact metamorphic processes. Tolman and Rogers in their recent paper conclude that the ore minerals were introduced by mineralizers during a ‘‘late magmatic stage,’’ and replace the previously formed silicate minerals. They apply the term magmatic to this process. Following their complete theory we must admit that the mineralizers, which they believe effeeted the replacement of silicates by sulphides, would be magmatic in ulti- mate origin. Their application of the term magmatic seems unfortu- nate, however, as the rocks in which the deposits occur were, accord- ing to their conception, solid rocks and not magmas at the time the ores were introduced. In order to avoid confusion the terms syngenetic and epigenetic will be used here. Syngenetic implies that the materials of the ore bodies were essential constituents of the magma before its consolida- tion and that the ore bodies were formed from material derived from the adjacent magma before or during its consolidation. Epigenetic implies that the ore minerals were introduced after the consolidation of the igneous rocks. The magmatic theories of most authors postu- late a syngenetie origin of the ore bodies. THEORIES OF SYNGENETIC ORIGIN In 1890 Dr. Robert Bell announced, as a result of his study of the Sudbury deposits, that the ores were syngenetice with the inclosing igneous rocks. The following is quoted from his paper: The ore bodies ... . do not appear to have accumulated like ordinary metal- liferous veins from mineral matter in aqueous solution, but to have resulted from igneous fusion. The fact that they are always associated with diorite, which has been left in its present positions in a molten state, points in this direction. As the diorite and the sulphides fuse at about the same temperature, they would naturally accompany each other when in the fluid condition.26 The bodies of molten diorite and the sulphides, being large, would remain fluid for a sufficient time to allow the diffused sulphuretted metals to gather themselves together at certain centers by their mutual attractions and by concretionary action. In the case of great irrupted masses of diorite, the bodies of ore which had formed near enough to the solid walls cooled and lodged with a mixture of the broken wall rocks where we now find them, while larger quantities, re- maining fluid, probably sank slowly back through the liquid diorite to unknown ep UNSHe wens 27 26 The diorite and part of the greenstone of the earlier investigators of the Sudbury district are norites. (F.S. H.) 27 Bell, Robert, Bull. Geol. Soc. Am., vol. 2 (1891), p. 135. 230 University of California Publications in Geology [Vou.138 In a later paper*® Bell states that the ores have possibly been modified by aqueous solution. Barlow at about the same time published an almost identical theory. He recognized three modes of occurrence for the sulphides. These are: (1) at contacts of diabase and gabbro against other rocks; (2) impregnations throughout the diabase and gabbro; (3) in veins sub- sequent to (1) and (2). The disseminated sulphides, while common in the basic igneous rocks, are absent from the elastic wall rocks at any great distance from the diabase and gabbro, and the sulphide- bearing veins are said to be rare.?® Von Foullon published an account of the Sudbury deposits in 1892. His theory of origin®® is in no way different from that of Bell and Barlow. In the following year Vogt published his work on the ‘‘ Formation of ore deposits through differentiation processes in basie irruptive magmas.’’*' He discusses not only the nickeliferous pyrrhotite de- posits but also those of titaniferous magnetite, magnetite, ilmenite, chromite, ete. Vogt concluded that the nickeliferous pyrrhotite de- posits are border facies of the accompanying igneous rocks and that their position at the borders of the irruptive masses is due to the fact that the sulphides as a liquid differentiate have been concentrated against the cooling surfaces, following Soret’s principle.*’ The fol- lowing is a summary of the observations which led to his conclusions : (1) The numerous deposits of nickeliferous pyrrhotite, in basie irruptive rocks, are of world-wide distribution. They form both mineralogically and geologically a sharply bounded ‘‘ world group’’ whose mineralogy is so simple and monotonous that we may discuss in common the collected occurrences of the whole world.33 (2) From the constant relation of the nickeliferous pyrrhotite deposits to basic irruptive rocks, it follows that they stand genetically in a regular rela- tionship to the rock in question.34 (3) The nickeliferous pyrrhotite deposits are often united to the irruptive rocks by gradational, petrographic transitions, to such a degree that one may draw the conclusion that the sulphide masses are not later penetrations into the irruptive rock, but that they were already present during the solidification of the rocks.35 (4) The norite magmas with which the ores are associated generally show a wholly extraordinary inclination to often very considerable splitting or dif- 28 Bell, Geol. Surv. Can., Ann. Report, 1890-91, pt. F, p. 50. 29 Barlow, A. E., Geol. Surv. Can., Ann. Rept., 1890-91, pt. S, p. 122. 30 Foullon, H. B. von, Jahrb. d. k. k. R. A., XLIII (1892), p. 223. 31 Vogt, J. H. L., Zeit. f. prakt. Geol., vol. 1, 1893. 32 Ibid., p. 265, pp. 271-283. 33 Ibid., p. 126. 34 [bid., p. 262. 35 Ibid., p. 262. 1922] Hudson: Geology of the Cuyamaca Region of Califorma eat ferentiation processes. In most cases one finds even in rather small masses a whole series of different varieties, often of rather dissimilar chemical com- position.36 (5) There is not a mathematic proportionality between the size of the gabbro fields and the amount of ore contained in them. However, it may be said that the ore masses in very small gabbro fields are always rather unimportant, and that the larger ore concentrations are all in the larger gabbro fields. ... In gabbro fields of less than 1000 square meters area the ore bodies appear to be unimportant. With an area of 3000 square meters, however, the sulphide de- posits are sufficient for work on a small scale. In gabbro fields of 50,000 to 200,000 square meters, that is, 0.05 to 0.2 square kilometers, we find many of the larger sulphide segregations of the Scandinavian peninsula. Finally the gabbro fields measurable in miles are only exceptionally wont to carry sulphide segregations.37 (6) The gabbros of southern Norway, leaving out of account the anorthosite and the saussurite gabbro, may be divided in two great petrographic groups: (1) olivine hyperite (olivine + diallage + plagioclase, with ophitie texture) ; (2) norite (rhombie pyroxene + plagioclase, with eugranitic-granular texture) with ‘‘gabbro-diorite,’’?’ which in general is thought to be uralitized norite. The olivine hyperite has here and there ‘‘oxide’’ segregations of ilmenite- enstatite. Further, there are apatite-rutile dikes, formed by ‘‘irruptive after effects.’’ The norite, however, is the mother rock of the most important sulphide segregations of nickeliferous pyrrhotite.38 (7) In most gabbro areas we observe normal pegmatitie granite dikes. Also dikes of pegmatitic, granite-like rock, carrying characteristic nickeliferous pyrrhotite. .... The latter type of dike, the so-called oligoclase-granite dike, contains at Romsaas, according to Meinich, nickeliferous pyrrhotite, chaleopy- rite, hematite, tourmaline, garnet, biotite, oligoclase, and quartz. The nickel and copper content are high enough so that the dike has been mined. In a similar dike at Erteli the ores and ferromagnesian minerals are concentrated on the borders of the dike, while the later crystallized plagioclase and quartz are in the center..... From the characteristic content of copper and nickel one may say with certainty that these dikes originated from splitting processes, in a similar way to the nickeliferous pyrrhotite concentrations.39 (8) There is a regular relationship between the absolute nickel content of the pyrrhotite on the one hand and the proportion of nickel to copper on the other. The higher the nickel in the pyrrhotite the lower the copper in pro- portion to the nickel.40 (9) In the segregations of magnetite and ilmenite not only the titanium iron oxides but also the ferromagnesian silicates are concentrated. Generally there is no corresponding phenomenon in the sulphide deposits, the ratio between ferromagnesian silicates’ and plagioclase being as a rule the same both in the pyrrhotite-norites and gabbros as in the normal, sulphide-free rocks.#1 Other observations made by Vogt having more or less bearing on his conclusion are: (1) In the pyrrhotite-norites and pyrrhotite-gabbros the pyrrhotite always reaches a solid condition at the end, after the individualization of the ferro- magnesian silicates and the feldspars. It follows from this that the rhombic 36 Ibid., p. 134. 38 Ibid., p. 132. 40 Ibid., pp. 129 and 264. 37 Ibid., p. 141. 39 Ibid., p. 135. 41 [bid., p. 138. Ooo University of California Publications in Geology [Vou.18 and monoclinic pyroxenes, the olivine, mica, ete., and also the plagioclase lie with idiomorphic contour within the pyrrhotite. They show, however, some- what rounded edges and angles..... That the pyrrhotite was in fluid condi- tion after the solidification of the silicate minerals is shown by the occasional fine veins of pyrrhotite that bend and split them.42 Garnet zones were observed at contacts of pyrrhotite and plagioclase.43 (2) Oftentimes fine ore veins or again thick ore dikes shoot off from the sulphide mass either into the gabbro or schist. Also we find corresponding veins, schlieren and dikes, in part of pyrrhotite-norite with varying sulphide content, in part of pure sulphide, within the gabbro massif, or more often in the peripheral part. These occur without relation to any observed regular ore concentration.4+4 (3) The copper always separates as chalcopyrite (CuFeS,). It never forms bornite (Cu,FeS,) or chalcocite (Cu.8), apparently due to the mass influence of the iron sulphide. Nickel concentrates in part in pyrrhotite (FeS,) and, with higher nickel content, in part also in millerite (NiS), pentlandite ([{ Ni, Fe]S) and polydymite (R,S,), that is, in minerals of low sulphur content.45 (4) Crystallization series. Crystals of pyrite, rich in cobalt, and of ilmenite are often found with good idiomorphic contour intergrown in the pyrrhotite and chalcopyrite. The pentlandite, millerite, and, to all appearances, also the polydymite are always of an earlier stage than the pyrrhotite. Chalcopyrite appears to be earlier than the pyrrhotite.46 Following Vogt’s paper many authors have advocated a ‘‘magmatie origin’’ for these deposits. Some have simply contented themselves with affirming a magmatie origin, not concerning themselves with the details of the process. Others have followed Vogt in applying Soret’s principle to explain the occurrence of ore bodies along the walls of the intrusive masses. For instance, Barlow, in a detailed account*’ of the Sudbury deposits, presents a theory for their origin much like that of Vogt. Coleman believes that the dominant process in determining the position of the deposits along the margins of the irruptive mass is eravitative settling of sulphides.** Hore also subseribes to the settling theory and believes that the accumulation of considerable masses of the pure sulphides may be explained by the limited miscibility of sulphide and silicate melts.*° Browne investigated nickel mattes and compared them with Sud- bury ores. He concluded that the nickel deposits of Sudbury existed primarily as eruptions of molten sulphides mixed with the constituents of the dioritie enclosures, and that by gradual cooling 42 [bid., p. 138. 43 [bid., p. 140. 44 Tbid., p. 137. 45 [bid., p. 264. 46 Tbid., p. 128. 47 Barlow, A. E., Can. Geol. Surv., Ann. Rept., vol. 14 (1901), pt. H, p. 125. 48 Coleman, A. P., Ont. Bur. Mines Report, vol. 12 (1903), p. 277; also in later papers by same author. 49 Hore, R. E., Can. Min. Inst. Tran., vol. 16 (1913), p. 271. 1922] Hudson: Geology of the Cuyamaca Region of California 233 the diorite was first separated, then the copper as copper pyrites, and the iron as pyrrhotite containing some nickel, and finally, in those portions remaining longest molten the nickel separated as a true nickel mineral.50 Vogt’s latest ideas, published as a part of Beyschlag, Krusch and Vogt’s textbook on ore deposits,’' depart but lttle from those in his earlier publications. He appeals to the theory of limited miscibility to explain the separation of sulphides from a sulphide-rich silicate melt. This is derived from Harker’s original statement of the ‘‘theory of limited miscibility in rock magmas.’”? Soret’s principle is still believed to be the explanation of many of the peripheral ore bodies, while the idea of gravitative settling is employed to explain the Sud- bury and certain Norwegian occurrences. As a result of detailed petrographic work on rocks from the Sud- bury ‘‘nickel-eruptive,’’ Dresser®* concludes that the larger masses of ore are syngenetie and that their segregation was due to their im- miscibility in molten norite. In addition to this, he believes that the partially consolidated norite contained liquid sulphides and ‘‘acid mother liquor,’’ which, as a result of dynamic action, may have been ‘*filter pressed’’ to regions of less pressure. This theory is used to explain the presence of sulphides found high up in the norite and the quartz and pegmatite of the lower part of the norite. This section of the report would be incomplete without reference to an important paper by Knopf, descriptive of ‘‘A magmatic sulphide ore body at Elkhorn, Montana.’’** The ore here consists of pyrrho- tite, containing no nickel, augite, and a minor amount of chaleco- pyrite. Brown hornblende, biotite, plagioclase, and quartz occur sparingly. The pyrrhotite and chalcopyrite are closely associated, the chalcopyrite, as seen both with the unaided eye and with the metallographic microscope, forming small, separate and distinct, solid particles surrounded by pyrrhotite. The avail- able evidence appears to show that the two sulphides are essentially contem- poraneous in origin. They occur either as interstitial masses between the augite grains, or as irregular intergrowths with them. It is noteworthy that the augite, although invariably anhedral where in contact with other grains of augite, shows a closer approxmation to its idiomorphic outlines where it is joined or surrounded by sulphides. Characteristic quadratic cross-sections with truncated corners are occasionally found. The grains of augite, where enveloped by 50 Browne, D. H., Col. Univ. Sch. Mines, Quart., vol. 16 (1895), p. 311. 51 Beyschlag-Krusch-Vogt, Die Lagerstatten der nutzbaren Mineralien und Gesteine (Stuttgart, 1914), vol. 1, pp. 800-311. 52 Harker, A., The natural history of igneous rocks (New York, 1909), pp. 196-200 (Harker’s statement is much clearer than Vogt’s). 53 Dresser, M. A., Econ. Geol., vol. 12 (1917), pp. 563-580. 54 Knopf, Adolph, Econ. Geol., vol. 8 (1913), pp. 323-336. 234 University of California Publications in Geology [Vou.18 sulphides, are, as a rule, somewhat rounded and smoothed as if by corrosion, and are frequently penetrated by the sulphides in distinct embayments, which resemble those so common in the magmatically resorbed quartz phenocrysts of rhyolitic rocks.55 The sulphide-augite mixture constituting the ore grades out to a quartz monzonite in a distance of from six to twelve feet. The quartz monzonite is of normal composition and appearance. Its plagioclase varies from Ab,, An,, to Ab,, An,,. The rocks of the transition zone are such as would be obtained by mixing the quartz monzonite and the ore in varying proportions. Their textures are hypidiomorphic granular and the lack of idiomorphism of their augite individuals is as pronounced as it is in the augite of the ore body. The plagioclase of the transition zone varies from Ab,, An,, to Ab,; An,,, a less calcic feldspar than that of the normal quartz monzonite. It would appear from his descriptions that pyrrhotite and chalcopyrite give way to magnetite, titanite and pyrite as accessory constituents at about four feet from the edge of the ore body proper. Knopf concludes that the primary igneous origin of the sulphide ore body .... is believed to be established by the following facts, stated summarily : (1) All the rocks, including that which composes the ore body and those which surround it, show an entire lack of pneumatolytie or hydrothermal alter- ation, such as the development of tourmaline, sericite, chlorite, carbonates, or other secondary minerals. They are fresh unaltered rocks in which the ferro- magnesian minerals are notably lustrous and the feldspars clear and vitreous. Such minor alteration as was noted is plainly owing to slight post-mineral action. (2) There is a textural relation of the sulphides to the augite as shown by the tendency of the pyroxene to show idiomorphic boundaries against the sulphides. This is a feature not easily explainable other than by the hypothesis of an igneous origin. (3) The zonal arrangement of basie phases of the quartz monzonite around the ore body indicates that a marked differentiation has taken place in the magma concurrently with the segregation of the sulphides. This differentiation is expressed mineralogically by the decrease of plagioclase, orthoclase, and quartz, and the concurrent increase in ferromagnesian mineral as the ore body is approached. The increase of ferromagnesian content, instead of appearing as hornblende or biotite, however, appears almost exclusively as augite in the ore body. It is noteworthy in this connection that if the differentiation took place through the agency of the mineralizers or the volatile fluxes of the magma, as believed by Michel-Levy, there is a conspicuous absence of flourine-bearing and hydroxyl-bearing minerals in the final product. Contrary to what might be expected under this hypothesis, the minerals biotite and hornblende decrease in amount with increasing proximity to the ore body.3é 55 Ibid., p. 330. 56 Ibid., pp. 335 and 336. 1922] Hudson: Geology of the Cuyamaca Region of California 235 THEORIES OF EPIGENETIC ORIGIN, INVOLVING REPLACEMENT Previous to the work of Bell, Barlow, and Vogt, the deposits of nickeliferous pyrrhotite were thought by all investigators to have been formed after the formation of the inclosing rocks by pneumatolytie or hydrothermal agencies. Thus in 1888 Collins advanced the theory that the Sudbury de- posits were concentrations of the copper that was originally dissemi- nated through the elastic or fragmental beds, this concentration taking place after the intrusion of the diorite. He was impressed by evidence of veining action and faulting and failed to note deposits enclosed entirely within the igneous rock.** Posepny, referring to the theories of Bell and von Foullon, stated that ‘‘these surprising statements assume a chemical impossibility, namely, the presence of metallic sulphides in the magma of the molten eruptive rock .... on the strength of metallurgical analogies.’’** This objection has not been put forward since Posepny’s time. There seems to be no theoretical basis for it, and, as a matter of fact, sulphides have been collected in samples of molten volcanic rock. Dickson from the results of a careful petrographie study of Sud- bury ores concluded that they were of epigenetic origin, formed by replacement processes along crushed and faulted zones.°® His obser- vations pointing to this conclusion are: (1) Brecciation, faulting, and shearing are everywhere characteristic. (2) The main brecciation and shearing was anterior to formation of the ore bodies proper. (38) Abrupt contacts of ore and barren rock and angular nature of rock fragments in the ore seem irreconcilable with magmatic theory. (4) Ural- itization and chloritization of the rocks is widespread and where fresh pyroxene remains it is breeciated. (5) This alteration is most marked near the ore bodies. (6) In general, the more complete the alteration of the rock the more complete has been its replacement by sulphides. (7) In all cases the sulphides show a tendency to occur along lines of weakness and in connection with fibrous min- erals. (8) Secondary quartz and calcite are often present in the ore in appreci- able amount while they are insignificant or lacking at a little distance. (9) Sulphides are practically lacking in the rock a short distance from the ore. The rock fragments included in the ore are also comparatively free from ore, except in veinlets.6° Weinschenk studied the nickel deposits of St. Blasien and ob- served phenomena much like those noted by Dickson in the Sudbury ores. The rocks here are thoroughly altered to a mixture of uralite and saussurite. The ore occurs invariably in the most altered rock 57 Collins, J. H., Quart. Jour. Geol. Soc. London, vol. 44 (1888), pp. 836-837. 58 Posepny, F., Am. Inst. Min. Engin., Trans., vol. 23 (1893), p. 330. 59 Dickson, C. W., A. I. M. E., Trans., vol. 34 (1903), p. 63. 60 Ibid., pp. 59, 60, 61. 236 University of California Publications in Geology [Vou. 18 and as it penetrates the hornblende is said to be later than the period of uralitization. The saussurite is cut by veins of clear quartz carry- ing pyrrhotite. The fresh rocks carry no ore.®t He concludes that the ‘‘world group”’ of nickeliferous pyrrhotite deposits belong more with true contact deposits, and are in no way magmatic segregations. Dickson’s conclusions as to the relation between the silicates and sulphides are supported by Campbell and Knight. They studied polished surfaces of the ores and believe that the order of formation of the various constituents, beginning with the earliest, is (1) magne- tite, (2) silicates, (3) pyrrhotite, (4) pentlandite, (5) chaleopyrite.% They conelude that the basic rocks were more or less fractured and ore-bearing solutions came in and replaced the rock matter wholly or in part by pyrrhotite. Later another period of straining and breaking was followed by deposition of pentlandite and chaleopyrite. They finally state that the foregoing explanation has been rejected by men of considerable ability who have studied the deposits in the field and that such geologists may put an entirely different interpretation on their work.** Reference has been made in the introduction to this chapter to the work of Tolman and Rogers. Their paper®’ presents the results of study of ‘‘magmatie sulphide’’ ores from most of the noteworthy de- posits of the world. Their summary of geologic literature of these deposits is good and their photographs of thin sections and polished surfaces of the ores and associated rocks are the best that have been published. Tolman and Rogers’ conclusions are: The ore minerals are the final magmatic product, and are formed later than the magmatic hornblende, which we believe to be produced by magmatic alteration. The ores replace the silicates and, in general, the later-formed ore minerals replace the earlier ore-minerals. There is a regular order of formation of the magmatic minerals, which shows no variation in the deposits studied. For the nickel-copper group of sulfid ores it is as follows: (1) silicates, (2) magnetite and ilmenite, (3) pyrrhotite, (4) pentlandite, and (5) chalcopyrite. .... All alteration minerals except horn- blende are later than the above mentioned magmatic ores.66 They state that in the Sudbury ores uralitization (tremolitization) occurred after the introduction of the sulphides.67 61 Weinschenk, E., Zeit. f. Prakt. Geol., vol. 15 (1907), Jahrg. Heft 3, pp. 82-84. 62 [bid., p. 86. 63 Campbell and Knight, Econ. Geol., vol. 2 (1907), pp. 353-365, 64 [bid., pp. 365-366. 65 Tolman and Rogers, A study of the magmatic sulfid ores (Stanford Uni- versity, 1916). 66 Ibid., p. 14. 67 Ibid., p. 31. 1922] Hudson: Geology of the Cuyamaca Region of California 237 We conclude that the ores are later than the silicates, for the reason that all the silicates indiscriminately occur as relicts in a groundmass of ore. The ore-minerals surround the silicates, enter along the contacts between them, cut them, and penetrate easily cleavable minerals such as biotite. In some cases they cut the silicates in well defined veinlets. These relations are explained, in part, by those favoring an early magmatic origin of the ores as follows: The sulfid ores remain in a molten condition during the formation of the pri- mary silicates (we add: during the formation of the late magmatic hornblende), and then solidify. ° From the latter part of the foregoing statement one would think that Tolman and Rogers believe that the sulphides existed at one time as molten substances, and one might conclude that their theory of origin differed from that of Vogt only with regard to the precise time when the sulphides solidified. That such is not the case is shown by the following quotation in which the authors clearly state that the ores came from without, and replaced solid silicate minerals: The process, however, is not one of corrosion, but of replacement. If the ores were molten, corrosion should produce metallic silicates by reaction. No such metal-bearing slag is found. The phenomena are those of ordinary replace- ment, and the agency that brought in the sulfids removed the dissolved silicates, all of which indicates active mineralizers.68 INTRUSIVE SULPHIDE THEORY From a petrographic study of rock from the Frood Mine, Howe was unable to conclude as to whether or not the ore and silicate min- erals were contemporaneous. On the other hand, he concluded from both field observations and laboratory study that the Creighton deposit resulted from an intrusion of pyrrhotite into already solidified norite, the differentiation of sulphides and silicates having been ef- fected, not in the place where the ores are now found, but in the magma chamber from which the norite originally came.*° He accepts the statement of Campbell and Knight that in the ore pyrrhotite is eut by pentlandite and these two in turn by chalcopyrite, but believes that the relations can be better explained by the ‘‘nearly simultaneous cooling of the different sulphides that had previously separated as distinct mineral compounds, non-miscible, though still molten.’’™ Bateman has presented an hypothesis which is a modified or am- plified form of that advanced by Howe. In brief it is that the Sud- bury deposits are to a minor extent due to magmatic segregation in place; in greater part to intrusions of pyrrhotite, as postulated by Howe, and in minor part to hydrothermal action.” 68 Ibid., p. 15. 69 Howe, E., Econ. Geol., vol. 9 (1914), p. 514. 70 Ibid., p. 521, 71 [bid., p. 522. 72 Bateman, A. M., Econ. Geol., vol. 12 (1917), p. 426. 238 University of California Publications in Geology [Vou.13 APPLICABILITY OF THE VARIOUS THEORIES TO THE F'RIDAY MINE DEposiIt Syngenetic theories—Three theories have been advanced to ex- plain the differentiation process by which syngenetie deposits of sul- phides are formed in igneous rocks. The failure of these theories to fully explain the origin of the Friday Mine deposit is shown by the following observations : (a) Segregation according to Soret’s principle. While in many districts the pyrrhotite bodies oceur at the edge of the irruptive masses, in other localities, as for instance the Friday Mine, the ore bodies are found well within the igneous mass. It might be thought that the schist body of the Friday Mine acted as the cool surface toward which the sulphides migrated. Again, certain outcrops of gossan that are found along the norite contact north of the Friday Mine are thought to represent oxidized pyrrhotite. If such is the case, we have here examples of deposits along the contact, and as the contact is nearly vertical Soret’s principle might be urged as against the idea of gravi- tative settling. Many ore bodies, however, belonging without doubt to the mag- matic class, occur within igneous recks at some distance from boun- daries and with no relation to ineluded bodies of older rocks. For instance, of numerous chromite deposits studied by the writer in the Coast Ranges of California, south of San Francisco, not one is located at a contact. Of some 200 chrome deposits examined by Mr. N. UL. Taliaferro in the Sierra Nevada only one was directly on a contact of the basic intrusive against older rock, and, taking into consider- ation the width of the various igneous bodies, the remainder: of the deposits can be said to be well within the igneous rock. The writer has seen one chromite deposit, at the Daisy Prospect, west of Jolon, in Monterey County, where the ore bodies occur along the median plane of a narrow body of serpentinized peridotite, and is informed that similar deposits occur in Montana."? From the above observations it seems very doubtful if Soret’s principle is the law under which magmatic ore deposits accumulate. (b) Gravitative settling. Evidently gravitative settling will not explain the Friday Mine deposit, and it appears also Inadequate to account for the supposed ore bodies along the steep north contact of the norite. 73 Mr. Geo. White, oral communication. 1922] Hudson: Geology of the Cuyamaca Region of Califorma 239 (c) Limited miscibility of silicate and sulphide melts. After studying the textural relations between sulphides and silicates in the norites, gabbros, and other basic.rocks that carry disseminated particles of ore, there can be little doubt that there was extremely limited misci- bility between the silicate and sulphide portions of the magma, immedi- ately prior to its consolidation. If this was the case with small particles of sulphide, it seems likely that it also held for the large masses. The theory of limited miscibility by itself, however, does not ex- plain why the sulphides aggregated into large, fairly pure masses. Intrusion of sulphide magma.—Howe and Bateman, while stating that some of the Sudbury deposits are the result of magmatic differ- entiation i situ, believe that the most of them were formed by the intrusion into already solidified norite of a sulphide magma, which formed by differentiation in the magma reservoir from which the norite came. At the Friday Mine there is strong evidence for differentiation, in place, of the sulphide mass from the norite magma. Not having seen the Sudbury occurrences and having examined only a few speci- mens from that locality, the writer is not qualified to pass judgment on the applicability of the intrusive sulphide theory to those deposits. It is thought, however, that one of Coleman’s objections to this theory is worth noting. He says: As mentioned before, pyrrhotite-norite is invariably found above the ore bodies in the marginal mines, and the enormous volume of this rock, running into cubic miles, is quite unaccountable if the ore was segregated before the norite reached its present position. These completely enclosed blebs of sulphides are like shots of matte in slag where cooling has advanced too rapidly to allow of complete gravi- tational separation. The pyrrhotite-norite probably contains as much ore as all the mines of the region, and if half the sulphides of the original magma are still enclosed in the rock, is it probable that the other half lagged behind and came up after the norite had cooled and solidified ?74 In other words, with a competent source, the disseminated sul- phides of the norite, at hand, why deny the possibility of differentia- tion in the norite body now exposed to view, and seek the locality of this action in some deeper magma chamber ? Epigenetic theories involving replacement.—The theories for the origin of nickeliferous pyrrhotite bodies advanced by Campbell, Knight, and Tolman and Rogers are based to a large extent on the observed textural relations between the various ore minerals and between these minerals and the silicates. 74 Coleman, A. P., letter to editor, Econ. Geol., vol. 10 (1915), p. 392. 240 University of California Publications in Geology [Vou.18 The writer has concluded that in the case of the Friday Mine deposit the preponderance of evidence points to a syngenetie origin. The almost complete lack of veining effects, either of silicate minerals by ore minerals or of one ore mineral by another, is noteworthy in this deposit. Even had such veining effects as are described by the proponents of replacement theories been noted in the Friday Mine ore, still the writer would have held to the syngenetie theory on account of the evidence of the larger scale geologic relationships. The reason for this statement is that he questions the validity of the criteria employed by Campbell, Knight, and Tolman and Rogers to establish the order of arrival of the various minerals at the partic- ular point studied. In the first place, it should be noted that both Howe and Dresser, who made careful petrographic studies of Sudbury material, deny the definite order in the relations between the sulphide minerals that has been affirmed by the other workers. Even if the various sulphides should cut one another in a definite order, and granting as a fact that the sulphides sometimes cut. the silicates in veinlets, no evidence has been offered that this proves the relative time of arrival of the minerals from some source outside the rock in which they are now found. Many examples might be cited of veins that without any doubt grew in their present positions with- out accession of any material from without, e.g., quartz veinlets in radiolarian chert, calcite veinlets in limestone, ete. Objection may be raised to such examples as being not pertinent to the present discussion. As offering almost perfect analogies to the nickel ores, we may turn to the evidence furnished by metallurgical products, e.g., mattes and alloys. Plate 4, figure 6 is reproduced from Fulton’s ‘‘Metallurgy.’’ It is a photograph of a polished surface of copper matte. The hght portion is substance ‘‘D’’ (Cu.8,-+ Cu) with dissolved FeS — Fe. The dark portion is metalhe copper. The textural relations between the metal and sulphide here are much like those between pentlandite and pyrrhotite in plate 13, fig- ure 1. Now substance ‘‘D’’ melts at something less than 1150° C., while metallic copper melts at 1084° C. The temperature of matte smelting generally exceeds 1200°C. It is evident, then, that the matte was entirely molten when poured from the furnace and that all of the solidification took place within the matte pot. The textural relations between the metal and the sulphide are the result of one 7> Fulton, C. H., Principles of metallurgy (New York, 1910), p. 305. 1922] Hudson: Geology of the Cuyamaca Region of Califorma 241 of two processes: either (1) two immiscible liquids, copper and sul- phide, were present prior to solidification, and the copper persisted in the molten condition after the solidification of the sulphide, and was thus able to vein the sulphide, or (2) a solid solution of copper in substance ‘‘D,’’ stable at the temperature of consolidation, broke down as the matte cooled. Fulton and Goodner have observed the sudden appearance of ‘‘moss copper’’ in mattes of comparatively low copper content when the matte was nearly cold but still too hot to bear the hand upon it. They sug- gest that the dimorphic point, 103° C., marks the throwing out of metallic copper from solution in the Cu,S—FeS.*° If this be so, then the second of the two processes suggested in the previous para- graph is probably the correct one. The ‘‘veining’’ of one constituent of cast manganese steel by other constituents is well shown in photographs presented by Potter’ and Young, Pease and Strand.** These are reproduced as plate 13, figures 3 and 4 of the present report, together with two photographs of Sudbury ores (plate 5, figures 2 and 5) whose textures are much like those of the alloys. It is obvious that the veins in the manganese steel do not prove that the ferrite or the troostite were introduced from without after the solidification of the ground mass. To the writer all these things go to show that veinliike forms of one mineral within another do not prove that the ‘‘vein mineral’’ was introduced from without, replacing the ‘‘ previously formed’’ minerals. Neither can we assume that in all cases the ‘‘ vein mineral’’ was molten after the solidification of the ground mass. It is thought, then, that the conclusions of Tolman and Rogers, and Campbell, and Knight, based on the minute textural relations of the minerals, rest on very insecure foundation. Without doubt there has been introduction of material from without after the primary ore formation in many of the magmatic ore deposits. It is thought that in many such deposits the secondary action has masked the primary relationships. In such eases conclusions as to origin must be based on large scale geologic relations, just as Vogt, Barlow, Bell, Coleman, and many others have urged. In the case of the Friday Mine deposit the absence of veining is considered as corroborative evidence pointing to syngenetic magmatic origin. 76 Fulton, C. H., and Goodner, I. E., A. I. M. E., Trans., vol. 39 (1908), p. 618. 77 Potter, W. S., A. I. M. E., Trans., vol. 50 (1914), p. 465. 78 Young, Pease and Strand, tbid., vol. 50 (1914), p. 427. EXPLANATION OF PLATE 9 Fig. 1. Thin section of norite. X 25. The relations between the hypersthene and the plagioclase are typical of the rocks of the Cuyamaca Intrusive. Fig. 2. Thin section of norite. X 104. Brown hornblende separating grains of plagioclase. Fig. 3. Thin section of olivine norite. XX 6.7. Plagioclase, light gray, hypersthene and olivine, darker gray. The hyper- sthene may be distinguished from -the olivine by its lower relief and distinct cleavage. The texture is typical of the Cuyamaca Basic Intrusive rocks. Fig. 4. Thin section of gabbro. X 25. Augite, darker gray, plagioclase, lighter gray. Note the exttontely irregular outlines of the augite. Fig. 5. Thin section of gabbro. X 32. Several augite sections, all parts of a single ophitic individual, associated with plagioclase. The augite is altered to a slight extent to green hornblende. Within the augite are several magnetite grains, associated in such a fashion with spinel, sp., that the two minerals appear contemporaneous. Fig. 6. Troctolite. Trains of olivine grains in plagioclase. X 6.95. [242] UNIV, CALIF. PUBL. BULL, DEPT. GEOL. SCI. [HUDSON] VOL. 18, PL. 9 EXPLANATION OF PLATE 10 Fig. 1. Same field as figure 6, Plate 9, but with crossed Nicols. Fig. 2. Thin section of hypersthene diorite. XX 25. Crossed Nicols. The texture is typical of the rocks of the Cuyamaca intrusive. Fig. 3. Photograph of thin section of ore from Friday Mine. X 25. Crystal of brown hornblende enclosed in sulphides. The dark substance in the center of the hornblende is chlorite, with which is associated actinolite in white ‘‘needles.’’ A rim of fibrous calcite surrounds the brown hornblende. Fig. 4. Photograph of thin section of ore from Friday Mine. X 25. Brown hornblende in sulphides. Fig. 5. Massive ore. > 12.5. Pyrrhotite shows parting cracks. Polydymite shows cubie cleavage. Chalco- pyrite distinguished by high luster and freedom from cleavage. Dark gray patches are gangue minerals. Fig. 6. Enlarged view of center of field shown in figure 5. X 25. [244] 10 es OF Sy VOI, [ HUDSON |] UNIV CALIE PUB SUES Darin GEOL Sir at ied + a EXPLANATION OF PLATE 11 Fig. 1. Massive ore, Friday Mine. X 25. Note the vein-like mass of chalcopyrite in the pyrrhotite. This vein stops abruptly against the silicate, showing that the two sulphides act as a unit in their textural relations with the silicates. Fig. 2. Polished surface of norite. X 233. Two simple grains of pyrrhotite inclosed within a single, fresh, unfractured silicate. Note that each of the pyrrhotite grains contains a minute mass of pentlandite. Fig. 3. Polished surface of peridotite. X 108. A vein-like mass of pyrrhotite connecting two grains of that mineral. Note the tiny ‘‘bar’’ of pentlandite lying across the vein-like mass near its middle por- tion, the pentlandite terminating abruptly against the silicate walls. Fig. 4. Polished surface of peridotite. X 233. Vein and grain of pyrrhotite inclosed in silicates. The vein-like masses shown in figures 3 and 4 are wholly exceptional, the two figured here being the only ones found in the detailed examination of eight specimens. Fig. 5. Polished surface of olivine gabbro. X 125. Shows a compound grain of pyrrhotite, white, and magnetite, gray. Fig. 6. Polished surface of olivine gabbro. X 108. Pentlandite at edge of a pyrrhotite grain. [246] UNIV. CALIF: PUBL. BULLE, DEPT: GEOL, SC, PAWDSONI-PVGLy ley PES ital Fig. 2 Big. 4 Fig. § EXPLANATION OF PLATE 12 Fig. 1. Polished surface of olivine gabbro. X 27.5. A typical sulphide grain. Shows pentlandite, white, and chalcopyrite, inclosed in pyrrhotite. Fig. 2. Enlarged view of portion of grain shown in figure 1. X 108. Fig. 3. Polished surface of norite. X 108. A typical sulphide grain, showing both pentlandite and chalcopyrite in the pyrrhotite. Fig. 4. Another grain from same rock as that of figure 3, plate 12. X 108. Fig. 5. Polished surface of olivine gabbro. X 108. A grain of pentlandite and wedges of chalcopyrite, inclosed in a pyrrhotite grain. Note the minute tufts of pentlandite along a calcite veinlet which cuts the pyrrhotite. These tufts are believed to be secondary pentlandite derived from the substance of the primary grains and deposited by the same agency that formed the calcite veinlet. Fig. 6. Copper matte. The light portion of the field is substance ‘‘D,’’ the dark portion is metallic copper. (Figure 100, Fulton’s Metallurgy.) [248] UNIV; CALIF, PUBL. BULE, DEPT. GEOL. SCl, PEHWIDSONITVGE, 13," Pir t2 EXPLANATION OF PLATE 13 Fig. 1. Nickel ore. Creighton Mine, Sudbury. Pentlandite, pn; pyrrhotite, p; magnetite, m; silicates, s. Fig. 2. Nickel ore. Creighton Mine, Sudbury. X 17. “¢Veins’’ of pentlandite in pyrrhotite. (Fig. 35, Tolman and Rogers.) Fig. 3. Cast manganese steel. X 78. ‘‘Veins’’ of ferrite in groundmass of other iron substances. (Figure 4, Young, Pease and Strand, Trans. A. I. M. E., vol. L.) UNIVECAL EG UB SUES Darin GEOL, Sicl: EEUDSONIIVOE, 1a \eREs1s EXPLANATION OF PLATE 14 Fig. 1. Cast manganese steel. X 392. Eutectic and troostite in a groundmass of gamma iron. (W. 8. Potter, Trans. A. I. M. E., vol. L, p. 465.) Fig. 2. Nickel ore, Creighton Mine. X 608. Chalcopyrite and pentlandite in a groundmass of pyrrhotite. (Tolman and Rogers, figure 36.) [252] VINIVGE (CALE RUBE, BUIEE, DEPT, GEOE. SC. [ HUDSON] VOL. 18, PL. 14 PUBLICATIONS BU THE DEPARTMENT OF - GEOLOGICAL SCIENCES| . 253-310, 3 figures in text, plates 15-16 May 31, 1922 el bs n DISTRICT, ONTARIO, CANADA BY / ~ ALFRED R. WHITMAN OS eaten ine 248 mes . UNIVERSITY OF CALIFORNIA PRESS . BERKELEY, CALIFORNIA GEOLOGICAL SCIENCES.—Anpkew 0. Lawson, Editor, Price, volumes 12. The Occurrence of Tertiary Mammalian Remains in Northeastern Nevada, by John CRE ost: ein a ena MARK we - 10e 13. Remains of Land Mammals from Marine Tertiary Beds in the Tejon, Hills, Cali- i fornia, by John C.. Merriam ..z.-5_..2.-..-cscpipecnsseods tease ceasposs Oeeuepe) ee 5e 14. The Martinez Eocene and Associated Formations at Rock Creek on the Western Border of the Mohave, Desert Area, by Roy HE. Dickerson 222... o..--sccscsotcteseaeteeeennt) 10¢ 15. New Molluscan Species from the Martinez Eocene of Southern California, by Roy mee FH, DACKCTSON, nw. -<-n222---ceanecennneoseccenuecontuncnsnantnanorenpesunsiesdna sabe iuatbectie ata pea 5e 16. A Proboscidean Tooth from the Truckee Beds of Western Nevada, by John P. : Ee w ioe) 10. . Is the Boulder ‘‘Batholith’’ a Laccolith? A Problem in Ore-Genesis, by Andre . Bird Remains from the Pleistocene of San Pedro, California, by Loye Holmes Miller. . 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Relations of the Invertebrate to the Vertebrate Faunal Zones of the Jacalitos and . The Owl Remains from Rancho La Brea, by Loye Holmes Miller .. UNIVERSITY OF CALIFORNIA PUBLICATIONS Re WILLIAM WESLEY & SONS, LONDON Agent for the series in American Archaeology and Ethnology, Botany, Geol Sciences, eo uee! and Zoology. volumes 8 and following, $5.00. Volumes 1-12 completed; volume 13 im p: list of titles in volumes 1 to 7 will be sent upon request. : VOLUME 8 Gu La WSOD - 6 oz a sen ncas Sa netzetecttnennnen dan odtecoasau cee ain gine Mees nee ey SE eee Note on the Faunal Zones of the Tejon Group, by Roy E. Dickerson .......2---c:--00--= Teeth of a Cestraciont Shark from the Upper Triassic of Northern California, by Harold C. 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Merriam bone obucensecte on fase sae eee aa VOLUME 9 . New Species of the Hipparion Group from the Pacific Coast and Great Basin Prov- fae : inces of North America, by John C. Merriam The Occurrence of Oligocene in the Contra Costa Hills of Middle California, by Bruce. Lis Clarke vic escort ce re not IN OMIM ANG oso ae cea cone aera ekce cee o ee AAR Ue aE Eat ee Ree Epo en ne ae Etchegoin Formations in the North Coalinga Region, California, by Jorgen Nomland sna dnacseansennnin cones JieSaecbscisoa cede o cuua sso ao ee eae ap eset Sec eee Se a a a ean A Review of the Species Pavo californicus, by Loye Holmes Miller .. MEU Y Sooo nde cabccacmenocecbeceecamecencuche cot oe acto aS Bae Se as ee, ee A eee = fe . + i. UNIVERSITY OF CALIFORNIA PUBLICATIONS BULLETIN OF THE DEPARTMENT OF GEOLOGICAL SCIENCES Vol. 13, No. 7, pp. 253-310, 3 figures in text, plates 15-16 May 31, 1922 GENESIS OF THE ORES OF THE COBALT DISTRICT, ONTARIO, CANADA BY ALFRED R. WHITMAN a ma CONTENTS eae Aira tir OCU CULO srt te sees te Se Se aces opto ea cesses Sicesnt se ras tides ieee ee nee APR re rte 40): Review of ideas current in 1915. TGC RES SPEDE A saat Ae a REE REET ee eee 254 HHO TN VG ONS ens tece eee scan see Corte ei roan. cece tuetes whet cuccaacatvresucdvscetateeoneasetees (locas eae PAD: ISURUCUULOS tescrcdtek eoade, Mistrncts-ctivAeecttsueisain Ae ee ek MC Oa ene, PAYS) Cobalt-silver veins... ccc eees Bee eee a eee OO Descriptive geology........0...0.0ccccccccee cece eeette cee ceteteesceeeteeees nist iahe Men geiacy ca PaO Pre=@o ball tiSUriaces..4..ccscssse.csa;ccosseyeedndbsaessdnestasesseréeseeetesnavseseevetras SMiieenes eee lO The diabase sill..:.....0...00.0cciccccecceseeeceeeeteceet eee 260 SONU COUMOS Frcs at sese sate cb spree ssceseye.servnutaysscdee¥e casa suss oy sSutiqeter tasnatteascetiadaivatierdastvactes 262 1G FFE 262 HAULS Mee oh ee ceca ae cxrcuace ee Me cuesesedthseeea he esas ee oceania recrian OOS SVOUNGS Hier cers eee casas dices eacssag eaela covets hau ibctctne Mtoe Bi be eeesta arte wea esau 200 Cobalt silver veins................ oy ee ee EN CMON cr ees treaty as OW. Wel CON CENUS etree cette tesiean ser serra eee eee meee mn eek ee eer eta ee eh aaa onsen aes 267 SVICINESUNUCUUMES eacnceenergereeee).eeuseuettscees eee et eteeety ore eer eck Piste Meaatae-aeaesscen nse einae 268 Space relations. .....0000...0..0ccccceeccceeseeeereeeeeen — a chr. ct cecstscive aloo IBAA CNESIS ees. te esse taee face ss eae eee inert vias. car scxaneeseeeen Pere eee oO The genesis of the O©e8.....00.00.00000.0cccccccceceeccceeceeceeesseeteseveevsereevevvaveee seesueer gaye thea 271 MDT AStrO PIS seeecv sees svlesssssescceees ss¥ensosesesedsaebessueeeasssteeseess g Ween cteeaee ie astra Oe 271 Major structural axes... ccccccccccecceecseetsereeeeeveeceenees EAE eeee 271 Injection of the diabase.0 cn, Se er eee se PAU Mimor Structures. ..........:.ccccccccesnseesesecseresseresevsvesesveressoes eT ere tne? eG SUI AT Arencdee ss ecrcoevene geste te cae caste revasttesstvoiaveqinst Oe osc oshy acs ase Ge A EO Current theories of vein genesis at Cobalt... ere xe!) Descending solutions. .........0.00.00:cccccccececeecsesevveecseees EG ese Peers OATS) Ascending solutions. ...........0..00:ccccccccceseceeeceeeveceveeveeeees Macey Ly angie sere 20) General réle of diffusion in vein genesis.. JO)s ost Resets asthe Moe aaa Ae COS Mode of genesis of veins at Cobalt by Hificeion Petia aptactessieteasets ewe DOD Inception of diffusion.....0..00..00000000.00 ee 2 a Cr ene ee ona eee aD Oy AVI Orr U1 Ta yam ee ene nae ee rien ade eek ty aa a eae See 297 Deposition... 7 aE. sciatic ate havent aes ees te Meee ue ete DOG) Subsequent molecular Pee eaientn seesstucbadeuah Alb avaee te teats ee Oe On clusionher stent Meum Met enh knits OR ct Rahs aM meas ae O03 Bibliography of the Cobalt district.........ccccccccccccccccscessevevevsvesvevevtevevavereeveees oe. BOB 254 University of California Publications in Geology [Vou. 18 INTRODUCTION The mines of the Cobalt district of Ontario, Canada, have long been known as large producers of silver. The precious metal occurs associated with the arsenides of cobalt and nickel in veins of calcite, varying in width from a fraction of an inch to eighteen inches. Usually the silver is disseminated through the arsenide in the native condition or in such minerals as dyscrasite, argentite, and proustite. Frequently, however, it is found native in ealcite, and locally it entirely displaces the gangue, filling the vein as a sheet of solid silver. Silver was discovered in Cobalt district in 1903 during railroad construction; and in the same year Willet G. Miller, provincial geol- ogist, made a preliminary study of the district. An official report was published by the Ontario government in 1904. Three later editions were issued, the fourth one appearing in 1913.3 Many geologists and engineers have visited the Cobalt District and much has been written about it. Various hypotheses concerning the origin of the ores have been suggested; but the deductions of Miller are probably the best known and most generally accepted. On account of the necessary limitations of this paper, I will not attempt to dis- cuss the various views of others; but, as a background for my own conclusions, I will give a brief résumé of the current conceptions as I found them upon beginning work. Grateful acknowledgment is due Professor A. C. Lawson and Dr. F. R. Bichowsky for helpful discussions and suggestions relating to the igneous and chemical problems dealt with, also to my assistants, Mr. W. L. Whitehead and Mr. Maurice Albertson. REVIEW OF IDEAS CURRENT IN 1915 Formations.—The oldest formation recognized consists of altered Keewatin lavas, tuffs, and rocks resembling sediments, penetrated by pre-Laurentian finegrained intrusives, the lavas and intrusives rang- ing from the most acid to the most basic. All these formations were folded and were intruded by gray Laurentian granite, which in time became exposed by erosion and mantled by the Timiskaming Series of 1 Ontario Bureau of Mines, Report, vol. 19, pt. 2. 1922 ] Whitman: Genesis of the Ores of the Cobalt District 255 conglomerates and finer sediments. These formations were, in turn, folded into nearly vertical attitudes, and were intruded by dikes of lamprophyre and batholithic masses of pink Lorrain granite. The complex was then eroded until the Lorrain granite was ex- posed and the Cobalt Series of conglomerates and greywackes was deposited in horizontal or nearly horizontal beds upon a land surface which, according to Miller, was hilly and rough. Miller refers to the Nipissing diabase as a sill between 600 and 1100 feet thick, probably of Keweenawan age, which was injected in an approximately horizontal position coneordant with the bedding or with the contact between the Cobalt Series and the Keewatin for- mation, the amount of overburden not being estimated. The diabase is supposed to have come from a local vent, though the possibility is admitted that there might have been more than one feeding channel. After intrusion this formation was in turn intruded by small dikes of granophyre and basalt, presumably representing segregation pro- ducts from the plutonie source of the diabase. At the beginning of the Silurian period the overburden and much of the diabase itself had been eroded away, and the region was sub- merged beneath the sea, where it remained until the Devonian, receiv- ing a thick mantle of richly fossiliferous limestone. By the close of the Pleistocene the limestone had been largely removed, and the underlying formations exposed over the greater part of the region. Structures.—Two systems of deep-seated structures were recog- nized as being in some way connected with the silver-cobalt deposits. They find topographic expression as long lines of depressions, occupied for the most part by streams and lakes. They trend respectively NW-SE and NE-SW;; and their age was held by Miller to be post- diabase. In regard to them Miller wrote: From the geological maps and the plan showing the distribution of the veins at Cobalt, which accompany this report, it will be seen that while belts of frag- mentary rocks strike approximately northeast and southwest, as for example, the belt along the railway at Cobalt, and the Glenn and Kerr Lake belt, the majority of veins have a strike different from this. It would also appear that the strike of the veins in this area has little connection with the disturbance which caused the great majority of the great rivers and chains of lakes in the district to follow one or the other of the well defined directions. The water courses and lake axes which lie in a northwest and southeast line are not so prominent on the maps as are the northwest-southeast ones just de- scribed. Still they form a not indistinct system, and as is indicated by Fig. 51, they seem to have an important, but as yet little understood relationship to the 256 University of California Publications in Geology [Vou. 18 Cobalt deposits of not only Cobalt proper, but of Rabbit Lake 30 miles to the south, Casey Township 15 miles to the northeast, South Lorrain to the southeast, and others. Believing that the occurrence of ore is in some way connected with the north- east-southwest lines of weakness, .the writer advised prospectors to search for deposits in the vicinity of Animanipissing. This resulted in the first finds of cobalt there. It was also recognized that folding occurred along NE-SW axes, and that Cobalt Lake hes in a syneline ruptured along its axis on what is known as the Cobalt Lake fault. Cobalt-silver veins.—The deposition of the ores was considered by Miller to have occurred along joints and joint-like fissures, which, he suggested, may represent cracks resulting from the contraction of the diabase shortly after its intrusion. The genesis of the ores was variously assigned by different writers to ascending juvenile waters or to descending meteoric waters. According to Miller: The relation of the veins to the intrusive flat-lying sill of Nipissing diabase is unique. The veins have not been filled by waters ascending vertically, as some writers on the Cobalt area have assumed; neither are the veins that are being worked the narrow parts of wide veins that penetrated the now eroded overlying rocks. It can not be proved that any of the veins in the Cobalt area reached the surface as it existed at the time of the intrusion of the Nipissing diabase. The occurrence of ‘‘blind veins’? makes it doubtful whether or not all the veins associated with the sill did not have a comparatively short vertical extension. The material in these veins has, in all likelihood, been deposited from highly heated impure waters which circulated through the cracks and fissures of the crust and were probably associated with .... followed... . the Nipissing dia- base eruption. It is rather difficult to predict the original source of the metals— silver, cobalt, nickel, arsenic, and others—now found in these veins. They may have come up from a considerable depth with the waters, or they may have leached out of what are now the folded and disturbed greenstones and other rocks of the Keewatin. Analysis of various rocks of the area have not given a clew as to the origin of the ores. However, the widespread occurrence of cobalt veins in the diabase or in close association with it, shown by discoveries during the last seven or eight years, throughout a region over 3000 square miles in extent, appears to be pretty conclusive proof that the diabase and the ores come from one and the same magma. The veins, as is generally known, occur chiefly in the Cobalt sedi- mentary series beneath the diabase sill; but good veins are also found in the sill itself, and in the adjacent Keewatin, both above and below it. The essential minerals of the veins as given in Miller’s report, in what he considers their order of deposition, are: smaltite, niccolite, (period of moving and fracturing), calcite, argentite, native silver, native bismuth, (period of decomposition), erythrite, annabergite. 1922 | Whitman: Genesis of the Ores of the Cobalt District 257 Proustite, breithauptite, dyscrasite; a long lst of unimportant silver and arsenic and other minerals is also recognized. The areal geology of the district has been mapped by Miller and Knight? and the reader is referred to their map. DESCRIPTIVE GEOLOGY THe Pre-CoBatt SURFACE The basement complex upon which the Cobalt Series was deposited is here referred to as the Keewatin, since that is the local usage. Its eroded surface has been found in the Cobalt area to be remarkably smooth and flat, such irregularities as may exist being much smaller than any of the hills of the present surface. One of the original irregularities is a low knob on the north end of Cobalt Hill about 2000 feet northeast of the low-grade mill of the Nipissing Mining Company, where the conglomerate of the Cobalt Series may be seen lapping unconformably against the lower slopes. Another irregularity occurs as a depression exposed by the workings of the Seneca Superior Mine. Other minor ones have been found here and there in the mines of the district, but they are never comparable in size with the major undula- tions caused by folding. Probably the Cobalt, Prospect, McKinley- Darragh, Lawson, and other hills of the district are not original irregularities on the Keewatin surface, but are anticlinal folds. In the course of my studies I constructed a contour map of the contact between the Keewatin and the Cobalt Series (see fig. 1). When the dips of the overlying sediments were superposed, they were found to conform to the slopes of this surface. Although the slopes le between 10 and 30 degrees, the depth of the sediments and the exactness of their parallelism with the lowest layers would seem. to exclude the possibility of sedimentation on slopes, since this condition persists for several hundred feet above the contact. Further evidence that the major undulations of this contact are due to folding hes in the fact that when the dips of a certain set of flatly inclined joints were plotted upon the formational contour map, they coincided with the contoured slopes, and with the dips of the beds overlying them. These flatly inclined joints are of a type pro- duced by shearing stresses during the folding of rock masses, and are parallel to the warped or folded surface. 2 Ontario Bureau of Mines, Report, (XVI), 1907. 258 University of California Publications in Geology [Vou. 13 The validity of this evidence is borne out by the fact of general shearing on the contact, accompanied usually by the development in the overlying sediments of large and small dip-slip reverse faults parallelling the contact in a rough way. Finally, further confirmation is found in the relations of certain other joints, particularly those which constitute the vein fissures. The origin of the flat surface of the Keewatin upon which the Cobalt Series was deposited is still obscure. The hypothesis of glacia- tion was tentatively discarded in view of the weight of evidence that SEA Fig. 1. Idealized plan showing relation of veins to folds. The contours rep- resent the Keewatin-Cobalt contact and the Keewatin-diabase contact respectively, the dotted lines veins, and the solid lines strike-slip faults. Scale 1” to 5000’. accumulated in favor of normal secular delay and stream erosion. All the evidence on this point offered by Miller has been corroborated by myself. A particularly convincing example in support of the idea of secular decay is found on the third level of the Buffalo Mine, where the old Keewatin bedrock can be seen with jagged serrations protrud- ing up into the ancient soil, in which angular fragments detached from the bedrock were mingled with rounded granite and other foreign pebbles, which had worked their way down through the soil. If the surface had been produced by the glacier assumed to have deposited the Cobalt Series, it must have been pared down sufficiently to remove the preexisting topographic features or to have considerably modified them. But had that occurred, then none of the residual soil of the older surface could have remained. The fossil soil found by Miller and myself must be regarded as a proof that the surface was not 259 Whitman: Genesis of the Ores of the Cobalt District 1922] ye Re 260 University of California Publications in Geology [Vou. 18 produced by glaciation. The character of the sediments points strongly to their deposition by streams, since the beds of greywacke interstratified with the conglomerate are not extensive sheets, but are discontinuous and lenticular, having been observed often to end abruptly against steep former embankments of pebbles. The exten- sive beds of clay and sand covering much of the present surface, which were left by the Pleistocene glacier, make a striking contrast with the limited beds of greywacke which characterize the Cobalt Series. THE DIABASE SILL On northwest sections constructed through the two Keewatin roof blocks of the diabase sill, on the King Edward and Nova Scotia prop- erties, respectively, the sill is found to have an average thickness of 1000 feet. The same approximate thickness was found at the Timis- kaming property, where the shaft was sunk through the sill. At Kerr Lake the base of the sill plunges down across the tilted Cobalt Series, making an angle of 40 degrees with the beds, which slope at 10 de- grees in the same direction; also on the west side of Peterson Lake the sill cuts across the sediments at a low angle, and down into the Keewatin; while at the Shamrock Mine the upper contact of the sill and the Keewatin takes a vertical attitude. The Keewatin roof blocks he between conglomerate areas on the under side of the sill, and hence must have been elevated vertically a distance of approximately 1000 feet. Evidently the sill was not injected in an even horizontal position, but only roughly approximated it, plunging at one point and arching at another, the contacts and the whole configuration of the mass being uneven. Attention must be called especially to the ereat plunge taken by the sill between Kerr Lake and the west shore of Peterson Lake, which area was probably originally covered by a continuous sheet of conglomerate. The Keewatin roof blocks le approximately along the axis of the depression. This is explained by the injection of the sill downward beneath the Cobalt Series into the Keewatin basement, and the lifting of the roof. The erosion of this lifted mass resulted in the almost complete removal of the conglomer- ate sheet, and the leaving of only three small remnants of Keewatin resting upon the sill (see fig. 2). It has been noted in the Rochester and neighboring properties that offshoots from the sill penetrate the Keewatin of the roof for short distances, and that blocks of Keewatin are found imbedded in the sill, representing fragments of the roof or floor torn loose by the moving magma during its injection; while in the Beaver Mine a block of 1922 | Whitman: Genesis of the Ores of the Cobalt District 261 Lorrain granite was found imbedded in the upper portion of the sill many hundred feet away from any known parent mass. In the South Lorrain district I found that the Nipissing diabase exposure is in no sense sill-like in form, but is a hollow arching shell plunging into the Keewatin in all directions around the enclosed area, having apparently once met overhead before erosion carried the higher portion away. In the Gowganda area also, it appears that the dia- base is more commonly dike-like than sill-hke in form. This points to the origin of these masses as many independent offshoots from a deep-seated mother magma, attempting to rise through devious chan- nels through the Keewatin, and stopped or deflected beneath a great thickness of flat-lying sediments, perhaps themselves overlain by a lava flood-sheet of the same magma. However hypothetical the assumption of such an overburden may be, the evidence nevertheless points to the existence of a heavy flat barrier beneath which the dia- base was forced to spread out, and assume irregular forms. The diabase is characteristically fairly coarse-grained, that is to say, it exhibits phenocrysts of plagioclase averaging from two to three- sixteenths of an inch in length. Its margins are characteristically fine- grained, usually aphanitic, visible phenocrysts not being discernible within five to ten feet of the contacts. In the interior of the sheet, however, the evenness of the texture disappears, and patches of coarse hornblende porphyry and pegmatitic material become more or less abundant. There are a few anomalous occurrences of diabasie impregnation of the adjacent Keewatin rocks in the form of small reticulate and ill-defined veinlets of diabase penetrating into the walls of the sheet, these veinlets or dikelets varying in width from one-half to less than one-sixteenth of an inch. One of these eases oceurs in the south workings of the Kerr Lake Mine on the under side of the sheet; and a careful study indicated that the space occupied by the dikelets was not produced by distension but by assimilation. Examples of this phenomenon, however, are rare. Sufficiently close study was not devoted to the post-diabase intru- sives to enable me either to add to or detract from what has already been written on the subject. However, as the matter bears upon a study of the diabase, and indirectly upon the problem of ore genesis, it received enough consideration to warrant the conclusion that these differentiation products, which form dikes cutting the sheet, did not come from the sill itself, since it has undergone only incipient segre- gation; but that they probably came from its mother-magma lying far below the surface. 262 University of California Publications in Geology [Vou. 18 STRUCTURES It has been found possible to follow out roughly folds in rock devoid of stratification and to detect and follow important faults and joints by the evidence found in topography and certain sets of other joints. This is because the joint systems express the structure, and because the chief method of degradation employed by the Pleistocene glacier was the plucking of joint blocks. The walls of faults are strongly jointed, and in consequence of this, the glacial plucking was most active on these lines, sculpturing valleys, and here and there precipitous escarpments, which in many cases overhang. On the limbs of folds, where gently inclined joints were developed by folding, making with oblique vertical joints rhombohedral blocks, the glacial plucking similarly exposed the structures. Folds.—All the folding was quite gentle, the usual minimum dip of the slopes being from 10 to 15 degrees, and the usual maximum being from 25 to 35 degrees for both major and minor folds. Prospect Hill on the west side of the town of Cobalt approximates a monocline, the area to the west being essentially flat save at one or two points where a slight westerly dip is visible. Cobalt Hill on the east side of Cobalt Lake is a slightly asymmetric anticline, the eastern slope into Peterson Lake being the gentler. The Lawson Hill immediately east of Kerr Lake, and the McKinley Darragh Hill southwest of Cobalt Hill, are also of a similar character. The Keewatin area between Cart Lake and Contact Bay on Giroux Lake is a nearly flat anticline. Of the two sets of tectonic forces which produced these folds the ereater acted along a NW-SE axis and tended to produce folds strik- ine NE-SW, as if the especially strong NW-SE structural lines were the outcrops of strike-slip faults between which longitudinal compres- sion occurred. The strength of the lesser set of forces is indicated by minor folds superimposed upon the northeasterly ones, and gen- erally striking northwesterly. As a rule the northeasterly or major folds are the older of the two, but in one or two cases major folds were at least accentuated after the development of the minor folds on their flanks. Although there is thus a simple sequence in the salient events, still in the lesser deformations there were various and indeter- minable alterations of strain from one major axis to the other. Faults.—In studying the geo-mechanies of the district it is neces- sary to picture a restoration of the region, and regarding the entire rock mass as a composite medium, to consider the mechanical peculiar- ities of each component formation. 1922] Whitman: Genesis of the Ores of the Cobalt District 263 The Keewatin is relatively plastic in contrast with the other forma- tions. This is due chiefly to its varied lithologie character and to its complex structure, which is reflected in the erratic nature of its joints. Certain strong vertical joints, however, occur in expected positions, notably the principal vein joints, and more particularly those near the diabase contact rather than near the sedimentary contact. The faults are particularly characteristic of the formation. All faults passing from other formations into the Keewatin promptly flatten their dips, and frequently change their strikes also. Usually, even though their actual displacements are small, they have considerable gouge, are accompanied by pronounced border zones of breccia and have slickensided walls. Their most significant and important feature is their discontinuity. A given slip diminishes in all directons from a center of maxmum displacement to a periphery of no displacement. Often where one slip ends another begins, lying parallel in an offset position. Also, the fault surfaces are so warped as in no way to approximate planes; and sometimes a fault clean-cut at one point will pass into a set of step faults or a distributive fault at another. The Cobalt Series is intermediate in mechanical strength between the Keewatin and the Nipissing diabase. It has the peculiar property of being plastic in one direction and elastic in another. It is well cemented and firm, and is highly elastic to stresses normal to the bedding, certain types of joints having a considerable extension in that direction; but along the bedding it yields plastically to slight stresses, so that bedding joints and bedding faults are very abundant. The diabase is the most homogeneous, elastic, and tough of the formations. Its joints frequently exhibit a conchoidal curvature, their junctions with one another being rounded with mutual branches in the four quadrants. Frequently also a curved or cuplike form is found in parallel joints closely set, like exfoliation fractures, or the layers of an onion. Even the faults often have very sinuous courses, the curves being from five to thirty feet in length. All the significant tectonic effeets within the district were produced shortly after the injection of the diabase, and presumably ended at a time not long subsequent to the dissipation of its initial heat. Dur- ing this time the chief structures developed were folds, indicating that there were no tendencies toward distension, and there was therefore no opportunity for the formation of gravity or normal faults. As a matter of fact no such faults have been discovered; and all known faults have resulted from compressive stress. 264 University of California Publications in Geology — [Vou. 18 When rocks are folded at a considerable depth below the surface, or under certain other conditions of uniform horizontal compression throughout a considerable vertical column, so that parallel folds are not possible, and only sinular folds* can be produced, shearing must develop on their flanks to accommodate the shifting of material from the limbs to the axes of the folds. As pointed out in a previous paragraph the axes of folding are also neutral axes with reference to shearing, and the regions of maximum shear are midway between them. The direction of shearing is that of dip-slip reverse faulting parallel to the warped surface. The surfaces of shearing in a thick homogeneous formation are distributed throughout its thickness, and are probably of small individual area, the displacement on each one being small; but in a flat bedded formation they probably coincide with the beds. In either case, here and there all local strains will be concentrated upon a single surface, which will, in consequence, have a large displacement and a large area. In such a ease the recognition of a fault is an arbitrary matter depending upon the quantity of dis- placement adopted as eritical for the definition of a fault; and all surfaces of shearing of less magnitude must be classed as joints. In the absence of any better means of designation, I shall refer to these as shear joints. During deformation strains must tend to be concentrated in regions of weakness, relief of one strain precipitating others until all local stresses are relieved, down to the lmiting strength of the material. In this manner, the contacts between formations, being lines of initial weakness, must become the chief loci of relief of strain; and in their vicinity faults and joints must be most abundant; this is notably true at Cobalt. This rule, however, is variously limited, and particu- larly applicable to contacts which were flat or nearly so before folding began, the shearing stresses due to folding being concentrated largely upon them, the very steep contacts being virtually immune. As would be expected the shearing and fracturing on the limbs of folds is pro- portional to the amount of folding. The Cobalt Lake fault is the only known local representative of either of the major systems, and is the chief reverse fault that is not related to the folding shear strains, having an oblique shift of 500 feet, at an angle of 25 degrees with the dip, toward the west. All other reverse faults are related to the folds, and dip with their dips at the same or steeper angles, usually striking approximately with their 30, K. Leith, Structural geology, p. 107. 1922] Whitman: Genesis of the Ores of the Cobalt District 265 strikes. On these the known shifts vary from one foot to approxi- mately 100 feet, making various angles with their dips on the surface of movement. Some of them are on bedding planes in the Cobalt Series, and can scarcely be detected at certain points except by the measured shift on them. Others are more obvious, carrying as much as four inches of selvage, and having crushed and jointed walls; but the amount of crushing seems to be quite unrelated to the amount of displacement, apparently being more closely connected with the kind of rock. Often, also, striae on the fault surface plainly indicate the direction of slip. Attention was called in a previous paragraph to the remarkable evenness of the original undeformed Keewatin surface upon which the Cobalt Series was laid down. It must be understood that this is to be taken in a broad relative sense. It is not conceivable, for instance, that it could approximate the evenness of a surface of sedimentation, but must necessarily have had small and perhaps gently undulating relief, the details of which could not now be defined, except by the fractures they would cause in the overlying formation as it was shoved over them during folding. These erratic fractures would tend to confuse the evidence gathered for use in other connections, without being of any value in themselves. Also, local strains would be set up by this means, which would be expressed as joints, sometimes, doubt- less, of such a nature as to constitute vein fissures. These erratic and misleading fractures have caused a certain amount of error in ore predictions; but their influence in comparison with the other factors is usually small. A distinct set of easterly-westerly faults is to be found in all parts of the district. They usually dip at angles varying from 45 to 90 degrees, the steeper ones predominating. They usually carry from one-half inch to six inches of gouge, and frequently have strongly striated walls, the striae often being perfectly horizontal. Now and then one set of striae is found crossing an older set. In one ease a vein of silver and smaltite had been deposited on a strongly striated fault, and two subsequent movements had striated the ore, so that a hand specimen exhibited two sets of striae making an angle of ten degrees with one another. They are not strike-slips nor oblique slips in the strictest sense, but range from one to the other. The shifts usually vary from a few inches to perhaps 50 feet; and they eut through all formations and folds. 266 University of Califorma Publications in Geology [Vou 18 Joints —The vein fissures are major joints of a type heretofore unrecognized, not being cooling cracks but being due to mechanical stress. They characteristically span the minor folds which pitch down the limbs of the major folds, more generally the minor synclines, or they le along the axes of the minor anticlines. They also frequently he along the dips of the major folds. They vary in length from perhaps 100 to 1000 feet, and in height from 50 to 500 feet. In their characteristic position, spanning minor synelines normal to their axes, they occur generally in groups of from two to a dozen spaced at intervals of not less than 30 nor more than 100 feet. Groups of this kind generally occupy the part of a minor syncline which has suffered the most acute compression. Their occurrence in these peculiar situa- tions, parallel to the folding stress which produced them, has led me to name them split joints. Major joints of this type have probably escaped the notice of other geologists, because by the time they usually become exposed to view on the surface by its degradation, the rock strains have been relieved by many lesser jomts which are much more closely spaced, and thus obscure the manifestation of this older, less numerous, and more sig- nificant type. The recognition of them at Cobalt was unavoidable from the fact that they are virtually the only joints mineralized, since they were the only ones open at the time and place of mineralization. The fact of their containing veins often of pure silver was the extra- ordinary circumstance that led to their being scrupulously followed by mine workings for hundreds of feet along their strikes and dips, and thus brought to hight. Other types of mineralized joints are of less importance, but require mention; they are: (1) fairly strong joints of either no dis- placement or very slight displacement parallel to and in the walls of inclined faults, (2) strong vertical joints branching from inclined faults, but parallel in strike, (3) lesser joints, vertical, branching from inclined faults, and parallel to their dip, (4) strong joints branching from strike-slip faults, nearly parallel in dip, but diverging in strike. All other joints are uncemented and have obviously originated after the period of mineralization. They are of two general classes, namely, those which are related to the cemented joints, and those unrelated. Each typical cemented joint is paralleled in its walls by one or more of the first class of uncemented joints; and each fault wall contains many and various joints of the same first class. Of the second class there is one type which bounds rhombohedral blocks situ- 1922 ] Whitman: Genesis of the Ores of the Cobalt District 267 ated and oriented not with reference to local structures, but rather to the major stresses. Jointing of this type is more abundant and more perfectly developed near the surface, and is to be regarded as a strictly surface phenomenon. Further notice of the uncemented joints is unnecessary beyond the observation that in general they grow less abundant and less perfectly developed with depth. Arsenides Silver Calcite Arsenides Sulphides Calcite (Silver) Calcite Sulphides Arsenides Quartz (Ag trace) Calcite Quartz Tremolite Sulphides Relative Number Quartz Calcite (Sulphide) U Fig. 3. Showing relation of vein content to dip of veims. COBALT-SILVER VEINS The veins logically fall into the following types, which are arranged in the order of their productiveness: (1) The first or normal type includes only veins formed in split joints. (2) The second in- eludes veins formed in major joints branching from or parallel to steep faults. (3) The third includes veins formed in faults. (4) The fourth includes veins formed in shear joints and faults of low dip. Vein contents—Caleite and dolomite are the characteristic gangue minerals, the latter being usually more intimately associated with the ores. The other constituents are grouped in the veins more or less together, and oceur in accordance with definite rules, very interesting and significant relations being discoverable in them. The rules are for the most part well represented by the accompanying diagram* (fig. 3), in which the richness of veins is shown to be proportional to their angle of dip. 4 After W. L. Whitehead, Econ. Geol., vol. 15, no. 2, p. 117. 268 Unversity of California Publications in Geology | Vou. 18 As values are apparently related to gravitative stress (all veins having been formed during the same uninterrupted period), so are they related to horizontal stress, vertical veins parallel to a line of compression being typically productive, and vertical veins normal to it being typically unproductive. Furthermore, in a given vertical vein, parallel to a line of compression and rising from a strong shear joint or fault of low dip, but diminishing and finally vanishing in all directions in its plane outward from the flat shear, the values are greatest at that central point, and are arranged fanhke on the plane of the vein, diminishing to zero at the edges. Thus at the center of the fan is native silver in large proportion, associated with dyserasite, and perhaps breithauptite, also with nieccolite or smaltite; in the semi- circular zone immediately next to it are chiefly niccolite or smaltite or both with more or less gangue; while in the third zone is only gangue. These, of course, are typical relations, being departed from in different ways and degrees under various conditions. Vein structures.—Although branching, reticulate, and offset veins are perhaps the rule, and twin or companion veins are more or less common, nevertheless the typical joint vein is a simple tabular body. Its walls, however, are not often sharp and free, but usually are ’ ‘‘frozen’’ to the vein, and frequently blend imperceptibly into it. Inclusions in the veins, and parallel veinlets in the walls, are the rule. Frequently there is such a gradual transition from inclusions of wall rock in the vein, to thinner and thinner veinlets in the walls, that it is impossible to say where one begins and the other ends. The aspect is altogether that of reticulate and branching fractures whose walls have been replaced by a volume-for-volume reaction. Veins fre- quently are banded, but not continuously nor symmetrically, the band- ing not being due to crustification, but apparently to stages in the growth of the vein by replacement. Crustification has been recognized in a few cases; but it is quite rare. Inclusions of wall rock are of all sizes and shapes, in most cases retaining the same orientation as the unaffected walls. A few instances have been noted where a vertical or steep vein has curved in its lower portion into a flat position, its mineralization changing as it did so according to the rule expressed by the diagram (fig. 3). In more cases, where a vertical vein rests upon or inter- sects a flatly inclined joint, the mineralization of one blends with the different mineralization of the other, as if they had been formed simultaneously. 1922 | Whitman: Genesis of the Ores of the Cobalt District 269 A few stopes of high-grade ore were developed on the Cobalt Lake fault, where at first glance it would seem that, according to the rule, ore of that quality could not occur; but on close study it was recog- nized that these kidney-shaped ore bodies occurred where the fault surface had been warped by a subsequent minor synelinal fold, as a result of which the stress conditions in the fault walls must have been locally disturbed, the transverse compression being relieved on the limbs of the fold, thus making a favorable situation for the deposition of ore according to the stress rule. The mineralization of faults even with calcite is usually discon- tinuous, and ore is very sparsely distributed. Another very significant relationship les in the fact that the richness of veins is related with fairly pronounced consistency to the number and strength of shear joints or flat faults which intersect them, as if these had served as feeders for the supplying of ore materials to the veins. Space relations—In a region deformed as this was, it may prop- erly be assumed that the folds, major and minor, with their various associated joints and faults, would not be limited to a particular hori- zon, but would be general throughout all known horizons; and this has been proved at Cobalt. The structurally favorable sites for ore deposition have, therefore, no immediate relationship to the diabase sheet. In view of this fact it is significant that only those favorable structures are mineralized which occur within 350 feet of the margins of the diabase, both in’ the diabase itself and in the adjacent Kee- watin, or within 550 feet of the diabase in the Cobalt Series. This apples at both upper and lower margins of the sheet, indifferently, to 187 stoped veins and many nonproductive ones, including all the veins of the district without exception, as well as all known veins of the South Lorrain, Casey, and Gowganda areas, not to mention other known occurrences of either silver or cobalt ores in northern Ontario. In connection with this, it is an interesting fact that the ore bodies show no distribution with reference to steep faults or other deep- seated structures or contacts, while either commercial or non-commer- cial veins of silver ore, cobalt ore, or calcite with traces of cobalt or nickel are coéxtensive, over large areas, with the Nipissing diabase. On a smaller scale, a very peculiar and interesting phenomenon is the relation of joint veins in the Cobalt Series to the bedding joints and faults, presenting the aspect of post-vein dislocations. Probably geological observers at&irst sight would almost unanimously pronounce most of these cases as prima facie evidence that the veins had been . 270 University of Califorma Publications in Geology [Vou. 18 dislocated. Long and careful study of many such occurrences, how- ever, has brought out evidence which seems to prove the contrary, namely, that the veins were formed in dislocated fractures. The fact that the surfaces of dislocation are not themselves mineralized with ore is the outstanding first-glance evidence against this interpretation ; but it is only superficial evidence, and is illusory. By turning again to the diagram (figure 1) illustrating the stress rule of deposition, the true explanation of this condition will be readily seen. A more complete discussion of this matter will be taken up in subsequent paragraphs. In the meantime a study of the accompanying vein photographs will be of service (pls. 15, 16). Paragenesis—In typical cases where calcite or dolomite is the gangue for smaltite, niccolite, breithauptite, and silver, it is found that in different spots in a given vein or in different veins the spacial relations of these minerals vary. It is a common thing to find sheets of silver lying in fractures and cleavages of the caleite or dolomite; but it is an equally common thing to find masses of smaltite in the midst of carbonate as if of simultaneous origin, with wire silver imbedded in the unfractured smaltite. Smaltite fringes occur on carbonate veins, and carbonate fringes occur on smaltite veins. Breithauptite is commonly associated with silver more intimately than is niecolite, and niccolite more intimately than is smaltite, and both occur in associations with smaltite and silver. It is therefore impos- sible to recognize any consistent sequence in origin. Silver in many cases occurs in fractures in smaltite and miccolite, and yet a very com- mon phenomenon is the occurrence of pellets of smaltite in dolomite, the pellets being from one to five millimeters in diameter, and con- taining a central pellet of niccolite or breithauptite, which in turn contains a core of silver, the metal being perfectly spherical in form. The carbonates vary from pure calcite to dolomite, containing notable percentages of iron or manganese, the latter imparting a strong salmon red color to many of the veins, and being regarded by the miners of ce the district as a ‘‘good sign.’’ The distribution of these various car- bonates makes it difficult to formulate rules that will consistently bear out any idea of regular sequence in origin. A rule embracing 75 per cent of the carbonate occurrences will not be sufficient to establish an age relation, for the 25 per cent of exceptions must be explained. The only rule which I have been able to develop is that the gray dolomite is the most usual associate of the rich ores, pink manganif- erous carbonate is next most closely associated with them, and white 1922 Whitman: Genesis of the Ores of the Cobalt District 271 ealcite is more generally the filling of barren veins; but to this rule there are many and notable exceptions. Native bismuth, dysecrasite, native silver, argentite, and proustite frequently occur in fractures in the ore bodies or in fractures in their walls, commonly penetrating the walls in this manner for distances up to 20 feet. This apparently sequential relation to the vein matter will be explained on a different basis in a later section. — THE GENESIS OF THE ORES Believing it to be a more scientific method of treatment, I have endeavored to separate, as well as possible, description and inference. Inference necessarily enters into description in the guise of interpre- tation, and description to some extent must accompany inference in eases where its value and bearing would not otherwise be fully appre- ciated. However, it is the purpose of this section of the paper to present as exclusively as possible the results of research without which the statistics would be valueless; for no one ean be in such a good position to correlate the facts of the case and indicate their significance as the one who gathered them; although he may not be able to present them in their entirety. DIASTROPHISM Major structural axes—A quotation in a previous paragraph shows that Miller suspected a genetic relationship between the cobalt- silver veins and certain major structures which are dominant through- out the mineral-bearing region, and which are indicated on the maps by long NE-SW and NW-SE chains of depressions, occupied for the most part by rivers and lakes. My observations have seemed to con- firm those suspicions in the sense that these lines appear to be expres- sions of the general determining structural factor connected with the genesis of the vein fissures. These and similar physiographic axes extend over a good portion of the pre-Cambrian area in Canada, but seem to be particularly pro- nounced on the map in the provinces of Ontario and Quebec. Their rule of arrangement apparently is that in any given area where system is observable, not more than two systems dominate, one being the com- plement of the other, save where one system represents the resultant between the other and its complement. In many localities described in the geological literature of Canada, these lines are known to be, or 272 University of California Publications in Geology [Vou 13 to be parallel to, lines of faulting or folding, or of foliation and meta- morphism. In some areas these lines are known to be of great age, and are believed to have persisted by continual renewal from the earliest geological times. My belef is that most of them are earth- joint systems or deep-seated complementary fractures resulting from the deformation of the earth, dividing the crust into blocks, and con- stituting surfaces of variable adjustment, sometimes serving thrusts in one direction, and sometimes in another, the chief component of displacement being horizontal. In the district about Cobalt these systems are represented, respec- tively, by the west shore of Lake Timiskaming, the Montreal River, the line of valleys including Cross, Kirk, Crown, and Goodwin lakes, and other parallel features, and by the axes of Kerr, Peterson, and Cobalt lakes, and the northwest arm of Lake Timiskaming. The exact nature of some of these local lines is not definitely known, but it seems highly probable that the west shore of Lake Timiskaming is determined by a fault which existed in pre-Cambrian time, and was renewed after the Silurian limestone was laid down, as indicated by the displacement and local tilting of the limestone. The evidence of pre-limestone fault- ing consists in the fact that the system of structures to which this fault belongs originated before the cobalt-silver veins, whose age is approx- imately Keewenawan. So far as exploration has gone, there has been no proof developed of the character of the Cross-Lake structure, but jointing seems to indicate an axial fault. Such a fault has been found on Cobalt Lake, and this fault is believed by Miller and myself to extend southwest- erly many miles, and northeasterly across Lake Timiskaming into the Province of Quebec. In the Meyer workings of the Nipissing Mine along ‘‘490 Vein’’ an abrupt slope occurs on the old Keewatin surface. It proved to be 30 feet or more in height, and several hundred feet in length, dying out to the southwestward, and reappearing in the northeast end of the Townsite Mine. A higher but shorter rise of similar kind was dis- covered in the Chambers-Ferland Mine adjacent and parallel to that on the ‘‘490 Vein.’’ Still another similar and parallel feature was found on Nipissing Hill north of the low-grade mill. The unconform- able lapping of the overlying beds of the Cobalt Series against these small ridges would seem to indicate that they represent pre-Cobalt relief ; and their parallelism with each other and the axis of the Cobalt Lake syncline, which is postdiabase in age, would seem to indicate 1922 Whitman: Genesis of the Ores of the Cobalt District 273 that at least a parallel drainage existed on the pre-Cobalt surface. If this can be taken as evidence that the major line now represented by the ruptured Cobalt Lake syneline existed during the carving of the pre-Cobalt surface, then on this line we have evidence correspond- ing to that along the supposed Lake Timiskaming fault to show that such structural lines have persisted in activity through long periods of time, the Cobalt Lake fault probably having been active from pre- Cobalt to post-Keewenawan time. Injection of the diabase-—Perhaps it is permissible to discuss in this place the injection of the sheet of Nipissing diabase, since I regard it as an important diastrophie ageney; and although interest attaches to other aspects of its advent, its participation in the production of significant structures is sufficient reason for its special mention. Attention was called in the first reference to the diabase to the fact that the margins are finegrained, indicating that at first the losses of heat to the adjacent rocks were more rapid than the accessions of heat from fresh arrivals of magma, and that the interior of the sill for 100 feet is of fairly even grain, and unsegregated. The mass must have slowly wedged its way into place, bodily lifting the roof an aver- age distance of 1000 feet. In the roof rocks of the sheet are certain faults and dykes of dia- base, which seem to have had their origin in the uneven lifting of the superjacent mass as the sheet slowly entered its berth. Also in the configuration of the mass itself, there are abrupt slopes’ which indi- cate that it was injected along a warped surface. It must be admitted that the roof rock was lifted irregularly, and suffered jostling first from one direction and then from another. The structural effects of this process are nowhere determinable with exactness, because the overlying sediments have been eroded away, and the heterogeneous character of the basement complex has been responsible for such a differential propagation of stresses that the deformations defy analysis. At the time of injection the Cobalt Series lay perfectly flat and undisturbed. The entering magma probably wedged open its own channel, since the form of it is quite arbitrary and undulating, in some cases following, and in others ignoring contacts and bedding planes. When the invasion was completed the sheet had a roughly uniform thickness over the entire area, but topographic relief was most likely reflected through isostatic adjustments as an influence tending to produce unevenness in the sheet’s thickness, which varies from 600 to 1100 feet, and more. 274 University of Califorima Publications in Geology [Vou. 18 The heat given off from the mass must have so expanded the adjacent rocks as to set up severe strains in them; but if the acces- sions of magma were as I have indicated in a previous paragraph, these heat effects could scarcely be discriminated from those which accompanied its contraction. In considering the mechanical effects of this magmatic heat it would be the logical thing to divide them on a time basis separated by the instant when expansion had reached its maximum. It is generally admitted that the heat conductivity of rock is very low, and that at the time of its injection an igneous mass does not impart its heat to a great thickness of wall-rock surrounding it. Assuming a depth of 24,000 feet, and a magma 1800° F. above the temperature of its walls, Daly°® calculates that in average rock at a distance from the magma of 400 feet no heat would be felt in the course of 16 years, and that in 100 years the temperature would have been raised only 283° F. In view of this it would be difficult to imag- ine that the vertical expansion of the foot wall of the diabase sheet at Cobalt could have amounted to many feet during the entire period of injection and solidification of the magma. However, the expansion tendency of this rock would not have been only upward; it would have been also lateral; and the summation of that tendency over the lateral dimensions of the sheet must have totalled to a force of considerable magnitude. The escape of this increased volume of rock, inhibited laterally, must have been upward; but its upward movement would have been caused by reaction against the force of its lateral expansion, taking the form either of reverse faulting or of folding. Since the margins of the sheet are chilled, and no assimilation of its walls occurred, it must have made room for itself by mechanical displacement, probably entering as a thin wedge, and splitting its own path before it. This procedure is evidenced by the indifferent transgression of the surface of injection across beds and contacts. It is very significant that the original undulations of this surface con- form to the major structural axes of the region, as if following a zone of weakness and shearing due to incipient folding on those axes. If it be assumed that the magma ascended from the depths along one of these axes, advancing laterally with a fairly even front from that starting point, then perhaps the lateral pressure resulting from the expansion of the underlying rocks would have advanced before its wedge-like front parallel with its initial alignment causing incipient folding parallel with the structural axes, which thus produced the zone of weakness invaded by the magma. This method of origin of the 5 Igneous rocks and their origin, p. 198. 1922] Whitman: Genesis of the Ores of the Cobalt District 215 undulations, however, is dubious, being possible only if the magma advaneed slowly. In any case, a secondary warping of the surface of injection in the first period of heat deformation would probably have been parallel with the chief structural axes and coincident with the original undulations of the diabase sheet, sinee those undulations represented directions of maximum length of the sheet, and axes of minimum resistance to folding. In the first heat period, deformation must have been caused chiefly by reaction against the lateral expansive force generated by the dis- tension of the wall-roecks. It would have behaved in every way as an external compressive force exerted parallel with the major strue- tural axes; and the folds induced by it in the diabase and wall-rocks must have possessed the usual characteristics of folds due to com- pression. But this folding would have deformed the plastic diabase, and would therefore have left no record in it. When the temperature of the immediate walls had become approximately the same as the interior of the sheet, expansion may, perhaps, be said to have attained its maximum. At that juncture the walls would have reached their maximum content of heat, while the diabase would, some time since, have been undergoing contraction. This condition must have pro- duced true cooling cracks in the diabase; and some of these might have formed avenues of escape for small quantities of aplitie and pegmatie material. This in fact appears to have occurred since the few vein-dikes of this material which have been found are in fissures which seem to have, as a rule, erratic orientations. From this point onward the sole influence in diabase and wall- rocks would be contraction. Not only would an arch or sag in the heated zone tend to draw in upon itself, matching its tensile strength against its own shearing strength, but the shrinkage of the entire length and breadth of heated rock would have borne in upon the regions of yielding, consisting of the initial undulations, tending to accentuate them by folding. This period of deformation would have left its traces in the diabase because this would have been solid and resistant. The foregoing suppositions are offered as an explanation of the observed fact that the folding of the district, affecting both the adjacent sediments and the diabase itself, developed innumerable large and small surfaces of shearing in both formations parallel with the surfaces of folding, which in their turn paralleled the original undula- tions of the diabase sheet. This phenomenon has been observed also to some extent in the South Lorrain and Casey areas. 276 University of California Publications in Geology [Vou. 18 On several of the lesser faults of the district evidence in the way of superimposed grooves on slickensided surfaces indicates movement in different directions at different times on a single fault. In view of such other evidence as reversed sequential relations in minor faults and joints, it seems clear that stresses on the complementary structural axes must have been active alternately in one direction and then in the other. From the orientation of the structures as described, it appears that the principal structural stresses must have been in a general sense simultaneously active throughout the period of deforma- tion which immediately followed the injection of the diabase. This being true, there must have been times when there was simultaneous stress from two oblique directions producing torsion effects; and this is borne out by numerous examples throughout the district, of groups of small gapping fractures arranged in echelon. Whether these stresses sprang from the same source as those which produced the major complementary structural lines, or resulted from movement upon them, or whether they were directly due to the shrinkage of the diabase and its environs due to the loss of heat, is difficult to decide; but whatever the source, it may be presumed to have been not spas- modie and variable, but continuous, the apparent alternations being due to the fact that the media under strain were of various strengths. The network of stresses over the region would thus be finding relief in a given direction at various points at the same time, and at inter- mediate points simultaneously in the complementary direction; here and there torsion would arise from the relief of strain in both diree- tions at the same time and place. Strain resultants might also be expected ; and fractures thus oriented are not uncommon. Minor structures—The most significant of the minor structures are the split joints, which occur most characteristically in groups spanning the minor syneclines, or extending along the axes of minor anticlines, or which occur singly and less frequently striking with the dips of the limbs of major folds. In detail, a split joint is typically a single strong major joint; but frequently it consists of a pair or triplet of fractures, or a chain of branching and reticulate fractures having a zonal width of between five and fifteen feet. The split joints in a major syncline have difficulty in completely spanning the structure, and are generally related to the limbs rather than to the structure as a whole; but a minor syncline is usually com- pletely spanned by them, and on its limbs they will intersect not only the shear joints developed on the sides of the major syncline down 1922 | Whitman: Genesis of the Ores of the Cobalt District 277 which the minor one pitches, but also those developed on the limbs of the minor syneline due to its own lesser folding. If minor synelines and anticlines pitch down the sides of a major syneline, and folding is renewed on the latter, then the minor anti- clines will act as resistant ribs tending to oppose the folding. They will therefore receive a heavy endwise thrust, and spht joints will develop along their axes, the earlier transverse spht joints at the same time being closed. However, if this renewed major folding were only slight, it might explain irregular conditions of stress in the walls of the two intersecting sets of joints. This is the anomalous condition under which mineralization took place in the veins of the Crown Reserve and Kerr Lake mines. It would seem that these joints must have been produced under conditions of large differential stresses capable of splitting the rock in such extensive fissures against a general three-dimensional stress due to the effect of gravity upon this resilient medium. There was a fracturing force, and a resisting pressure which tended to limit frae- turing to such places and intervals as would give the maximum relief to the differential stresses, with the minimum of openings. It must be inferred from the facts thus far presented that when the vein fissures originated the rock containing them was at a sufficient depth below the surface to be incapable of developing small joints. The measure of that depth can only be roughly approximated. From the nature of fractures generally encountered in mining operations, I would postulate a depth of several thousands of feet; and this may well be assumed, for the time which elapsed between the invasion of Nipissing diabase and the carving of the surface upon which the local Silurian limestones were laid down, probably includes the Cam- brian and Ordovician periods; and in that span of time there may have been considerable material eroded from this region. The expla- nation of the existence, position, and character of the gaping fractures must then lie in the reduction of gravitative stress effected by the degradation of the surface. These fractures have opened in the walls of cemented split joints and elsewhere in further relief of the elastic deformation produced during the folding. The steep easterly-westerly faults, although in some instanees strik- ing due east and west, and frequently departing from that direction by only small angles, vary in important instances from a strike of N70 W to S70 W. The major structural axes of the region strike respectively N 35 W and S 42 W, the major folding having occurred 278 University of California Publications in Geology [Vou. 18 parallel to the latter axis. If before deformation, a circle had been drawn about the area at the horizon of the present surface, after deformation it would have had the form of an ellipse whose longer axis would have been only shghtly greater than the short one, and would have had a strike of perhaps N-S. The two diameters connect- ing the four points of intersection of the circle and the ellipse might then have had strikes approximating N 70 W and S 70 W respectively, these being axes of maximum shear."° This may explain the mysterious easterly-westerly faults. The difficulty with this explanation, how- ever, 18 that. it implies contraction in one horizontal direction and elongation in another, whereas the escape of material due to the two- fold compression must have been upward. It would seem more satis- factory to regard these faults as expressions of the resultant of the two horizontal compressive stresses as they acted upon non-homo- eeneous media, the variations in strike representing the intensity fluctuations of the forces. At any rate these faults seem to be closely tied up with the deformative forces which accompanied the cooling of the diabase, since they traverse it, and in two instances, where they meet the Cobalt Lake fault, are dislocated by it. One of these is on the La Rose property northeast of Cobalt Lake, and the other, on one of the Hudson Bay claims southwest of the Lake. The fact that such faults sever the diabase sheet, as in the O’Brien and Beaver mines (although seareely dislocating it), need cause no confusion in this regard, since the compressive stresses caused by the radiation of mag- matic heat were generated not only in the diabase mass itself, but also in the heated rocks adjacent. Summary.—The significant relationships of time and structure in the ores of the Cobalt District probably center about the advent of the diabase. The Cobalt Lake fault in its earliest activities dates back to the early part of the erosional epoch preceding the laying down of the Cobalt Series, the supposed Timiskaming fault dates back at least to pre-Silurian times, and each of these faults represents one of two oblique complementary systems of lines of deep-seated diastrophic adjustment. These axes of strain presumably determined the warped surface along which the diabase sheet opened its way during injection, as it assumed its present position, lifting the roof rock a distance of 1000 feet. Its advent was accompanied by deformations due to the heat-expansion of the neighboring rocks which were slowly raised to the same temperature for a considerable distance back from the magma. 6C, K. Leith, Structural geology, p. 16. 1922] Whitman: Genesis of the Ores of the Cobalt District 279 As the diabase sheet cooled and contracted, it tended to accentuate its own undulations parallel to each of the major tectonic lines; and when this process was completed the force exerted by the cooling magma was greatly exceeded by the contraction of the inclosing rocks. This shrinkage, conformable with the two controlling teetonie axes of the region, gave rise to folds parallel to them, and at the same time gave rise to associated faults and joints. The Cobalt Lake fault reopened as a rupture along the axis of the Cobalt Lake syneline, displacing the Cobalt Series a distance of 500 feet diagonally upward, disloeat- ing certain of the easterly-westerly faults, and being followed by fold- ing parallel to the other axis. As these deformations began, the first effects were the inception of NE-SW folds accompanied by the development of shear joints and reverse faults, then by split joints and the E—-W faults, then by dislocation on the Cobalt Lake fault; then came minor folding superimposed on the other, parallel to the NW-SE axes, and the warping of the surface of the Cobalt Lake fault where two of these minor synelines cross it. There followed further intensification of all the folds, and the considerable dislocation of many split joints on shear joints and flat dip-slip reverse faults. Then came the ore. CURRENT THEORIES OF VEIN GENESIS AT COBALT Descending solutions —In view of the fact that these veins con- tain large percentages of native silver, dyscrasite, argentite, and proustite, easy first thought supposes that they may have originated through processes of downward secondary enrichment. Some writers have suggested that the veins at Cobalt may be the roots of vertically more extensive veins of cobalt and nickel poor in silver, which have been enriched through the solution of the silver of the upper portions of the vems in the products of their oxidation, and its redeposition in their lower portions through the precipitating agency of. smaltite and niecolite. Research may have demonstrated the feasibility of this precipitation process; but it is more relevant to the problem in hand to consider whether such solutions could ever have been delivered to the cobalt veins. The consideration of any one of a number of conspicuous con- ditions would suffice for the rejection of any idea of downward secondary enrichment. First of all, the products of oxidation of the veins would be preponderantly arsenious and searcely at all sulphur- ous; and at no place in the district are the lower portions of the 280 University of Califorma Publications in Geology [Vou. 138 deepest veins different in composition from the upper portions of the outcropping veins, there being no evidence that either silver or the other metals ever existed in that region in any other condition than that in which they are found just below the outcrops. Furthermore, no veins at any time in the camp’s history have shown consistent oxidation to a depth of more than a few inches or feet, except in two or three anomalous cases due to peculiar local conditions; and no con- sistent nor even certain enrichment has been found below these insig- nificant zones of oxidation. Generally where arsenides outcrop they are fresh and unoxidized, or only crusted with a thin layer of erythrite or anabergite. Many veins which have proven rich in their lower portions grade upward into barren arsenides and then into unmixed calcite. In addition to these facts it is important to recognize that the water table throughout the northern portion of the Province is virtually at the surface; and it is highly improbable that it has ever been lower. Ascending solutions —After many years of mining it has become strikingly apparent that the ore bodies are distributed marginally with reference to the sheet of Nipissing diabase. Probably the depo- sitions of ore were equally distributed with reference to both margins; so far as available evidence goes, that is true; but on account of erosion the chief production of the district has come from beneath the dia- base. If the source of the ore were the visible diabase mass, it would be difficult to understand how this condition could have been brought about by ascending waters. If another igneous source is assumed it must have reached the level of the present surface, or have betrayed — itself in some other manner; or else it must lie far below the present surface; but no such intrusive synchronous with or subsequent to the diabase has been found. If such a deep source is postulated, then the means by which its emanations reached the present horizon must receive scrutiny. When attention is given to possible ore conduits and channels of distribution, it is recognized that the strike-slip faults, as a rule, having horizontal lengths of less than 4000 feet, and being due to hori- zontal stress, probably have less vertical lengths, while the common dip-slip reverse faults lie only on the limbs of the folds. The only faults, therefore, which could be presumed to penetrate to the required depths would be those on major tectonic lines, of which the only known representative in or near the mining district is the Cobalt Lake fault. There is known to be no such fault along the Peterson Lake 1922 ] Whitman: Genesis of the Ores of the Cobalt District 281 syneline, nor the Kerr Lake anticline, nor in the neighborhood of either Glenn Lake or the Timiskaming and Beaver mines; and yet those have been very productive localities. Also the Cobalt Lake fault has not been productive to any notable extent, only small quantities of ore occurring within 400 feet of the surface for very lmited dis- tances along its strike, much exploratory work having been done on it only to prove it generally barren. ‘Those who look to ascending solutions for the origin of these ores should certainly expect to find such a fault lined with ore bodies, or to find the ore bodies of the dis- trict grouped with reference to it. If they say that the ore-bearing solutions ascended along it, and upon reaching the diabase contacts, spread out along these to do their work, the answer is that, if that is true, those solutions then began at once to deposit ore in neighboring fractures—selecting only one particular kind—and that they must then have moved along these undulating contacts, ascending and descending, as far as the Timiskaming mine, where ore bodies as good as any in the district were deposited, no trace of these solutions being left along the contacts themselves. In view of the obvious difficulties in the way of this supposition, and the conspicuous seareity of ore on the Cobalt Lake fault, the theory seems entirely untenable. It is further to be noted that although commercial ore bodies have been mined in the South Lorrain, Casey, and Gowganda areas, no faults of any description have been found to carry notable quantities of ore there, and the ore bodies mined seem to be wholly unrelated to any sort of faults or steep contacts. Even in the Cobalt district where rich ore bodies have been mined on steep-dipping minor faults, such occurrences are the exception rather than the rule. In times past there was waged a notable controversy on the matter of the circulation and burden of underground waters, one side main- taining that the source of ore-bearing waters lay in congealing intru- sive masses, while the other side held their origin to be atmospherie. The waters were presumed to be either juvenile or meteoric, and to have circulated in such quantitity along the sites of ore-deposition as to have brought thither, in spite of their acknowledged diluteness, all the ore-forming substances. It is interesting to note that each side showed the suppositions of the other to be untenable, and its kind of water to be incapable either of acquiring an adequate mineral burden or of flowing in sufficient quantity to accomplish the work ascribed to it. In my study of the problem of vein genesis at Cobalt I have been forced to the conelusion that each side in that controversy was correct in its exclusion of the claims of the other. 282 University of California Publications in Geology [Vou 18 In the year 1893 Franz Posepny expressed his idea that the bulk of mineral-bearing waters are essentially meteoric. He said:* ‘‘There is a descent of groundwater through the capillaries of the rock, even in the profound region. Having arrived at a certain depth it is prob- able that a lateral movement takes place toward the open channels. Having reached these it returns, ascending to the surface.’’ In this opinion C. R. Van Hise coneurred. He defined capillary sheets as having widths varying from 0.204 mm. to 0.0001 mm., and indicated his behef that heat, pressure, and time must tend to increase the mobility and flow of water in the deep regions, as against the counter effects of friction and discontinuity. He says: We conclude from the foregoing, that while underground circulation of water upward, downward, and lateral, is a possibility within the zone of rock flowage, it is very slow, and that it can not be appealed to to explain metalliferous de- posits.8 However, the ores are directly derived from rocks in the zone of fracture by circulating underground waters. The rocks which furnish the metallic com- pounds may be intruded igneous rocks; they may be extruded igneous rocks; they may be original rocks of the earth’s crust; they may be sedimentary rocks; they may be the altered equivalents of any of these.? .... Hence so far as the main work of ore deposition is concerned, the water is that of the zone of rock fracture, and this water is water of meteoric origin, which makes its way from the surface into the ground, and there performs its work and issues to the surface again. T. A. Rickard also concurred ;'° and A. C. Lawson treating the subject at greater length said :4 t=) t=) The circulation of the ground-water would in every case be profoundly dis- turped by the injection of hot igneous magmas into sedimentary terranes. The disturbance would, however, be far from chaotic. The presence of the hot body would be the controlling influence in determining the circulation. The circula- tion would always be upward on the periphery of the hot mass. This would be true not only while it was still molten, but also long after it had solidified. Such a circulation of the heated ground-water would be quite competent to do all that is ascribed to magmatic water, including the formation of lime-silicate zones. It would not only bring to a zone of active chemical reaction the materials leached from the surrounding region, but it would attack the still hot, though solid, igneous mass itself and abstract from it part of its metallic constituents. .... I will first, however, disclaim the belief, which I fear will be imputed to me if I do not anticipate the imputation, that the sedimentary rocks of the earth’s crust everywhere contain similarly large quantitics of water..... The inequality of 7 The genesis of ore deposits, p. 38; also A. I. M. E. Trans., vol. 23, p. 197, 1893. 8 Some principles controlling the deposition of ores, A. I. M. E. Trans., vol. 30, Dp. 40. 9 Op. cit., p. 46. 10 Eng. and Min. Jour., Feb., 1894. 11 Ore deposition in and near intrusive rocks by meteoric waters, Univ. Calif. Publ., Bull. Dept. Geol., vol. 8, p. 221, 1914. 1922 Whitman: Genesis of the Ores of the Cobalt District 283 distribution is, however, due to the variation in size or in prevalence, or both, of the voids in the rocks..... Nevertheless all sedimentary rocks below the water-level are saturated to an unknown but great depth. But saturation does not imply an abundant flow to a conduit or fissure... .. But making all allow- ance for this diminution of storage capacity there is a vast quantity of water contained in the sedimentary rocks in their unaltered state at all depths; and at high temperatures, which are an essential condition of our problem, the rate of flow and therefore the rate of escape to fissures, ete., is undoubtedly accelerated. Moreover, brittle rocks such as quartzite, sandstone, and limestone, which have been folded and otherwise disturbed, are usually traversed by fractures, faults, and joints, and these, together with the partings of stratification, afford compara- tively free access of surface waters to the limit of the zone of fracture of such rocks. He also points out that both walls and periphery of an igneous mass will probably be fractured as a result of cooling phenomena, and that the ground water will move laterally through fractures and through them ascend both beside and through the igneous mass. Farther on he says: The failure of ‘‘evidence of fracture or paths which could have been followed by the water’’ applies equally well to magmatic as to meteoric waters, and is of little moment when we reflect that the water in either event was probably in the form of superheated steam. In the coneluding paragraph of this same paper Lawson says: Now if the view which Spurr expresses is correct, and it is substantiated by a great many observations, the hypothesis of magmatic waters becomes far-fetched and difficult of acceptance. It throws us back for the source of the solutions upon a residual differentiate far in the depths, as Spurr holds. It fails to account for the restraint of the magmatic waters till this residual stage is arrived at. It assumes great depths for small intrusions which were probably injected from narrow vents. And it fails to explain the peripheral disposition of the ores deposited from the waters thus rising from a presumably central reservoir. Waldemar Lindgren in his ‘‘Mineral Deposits’’!* indicates his belief that the flow of water through rock pores is exceedingly meager and practically mil at really moderate depths. Kemp and Fuller have both brought out the fact that the deep sedimentary beds are often remarkably dry. The well 4262 feet deep at Wheeling, West Virginia, was in absolutely dry rocks for the lower 1500 feet. Wells sunk at Northampton, Massachusetts, and at New Haven, Connecticut, to depths of 4000 feet have failed to obtain water. A number of other instances are mentioned, and in many cases the dry part consists of sandstones or other porous rocks. Again he says: Van Hise suggests that the decreasing density and viscosity of water at higher temperatures may lessen the head necessary for ascending springs, but it may be doubted whether these factors would ever offset the great friction encountered during the downward passage. 12 Edition 1919, p. 29. 284 University of California Publications in Geology [| Vou. 13 Also: In conclusion it is believed that water in quantities sufficient to supply an ascending circulation can only exceptionally attain a depth of 10,000 feet and that, except in regions of great dynamic movements, the active circulation is con- fined to the uppermost few thousand feet. More commonly the depth of active circulation is measured by the level of surface discharge and the water below that level is practically stagnant; the lower limit of the body of stagnant water then forms an irregular surface descending to greater depths along the fractures and rising higher in the intervening blocks of solid ground. In regard to the magmatic origin of mineral bearing waters Lind- gren says in a later chapter :° The water existed in the solution constituting an igneous magma. Crystalliza- tion of the magma or its irruption into higher levels of the earth’s crust liberated the water as one of the most volatile constituents, thus permittinig its ascent to cooler regions. Such water may be called magmatic or juvenile. Then: Volcanic phenomena are almost always accompanied by the emissions of large quantities of steam and other volatile substances, and geologists generally have agreed that part of this water is a contribution to the atmosphere and hydro- sphere from the magmas..... Regarding plutonic rocks the direct evidence is lacking but indirect testimony is supplied by the inclusions of aqueous solutions found in granular rocks and by the presence of minerals like mica and amphibole which contain the hydroxyl molecule..... The best general evidence of the existence of juvenile waters is furnished, not by observation of the present springs, but by the study of old intrusive regions. Here the granites merge into pegmatite dikes, the latter change into pegmatite quartz, and this into veins carrying quartz and metallic ores, such as cassiterite and wolframite. Here we have evidence difficult to controvert that dikes consolidated from magmas gradually turn into deposits the structure and minerals of which testify to purely aqueous deposition; this admitted, it is difficult to see what would prevent such waters from reaching the surface in the form of mineral springs. ... The constant admixture with vadose waters forms another difficulty, but accounts well for the many derivatives of varying characteristics which accompany every spring of deep-seated origin. . .. Much more work must be done before we shall be able to establish the magmatic origin of any given spring. J. F. Kemp" in general agreement with Lindgren, argues that at varying depths below 10,000 feet the friction resistance offered to the flow of ground water in fissures must seriously limit its mobility and the quantity which can descend or flow laterally ; while at higher levels the significant circulation of descending waters, in so far as they move in notable volume, must be confined chiefly to fissures. On the basis of experiments performed by himself he points out that the volume 13 Chap. VI, p. 87. 14 The problem of the metalliferous veins, Econ. Geol., vol. 1, no. 3, p. 225, Dee.-Jan., 1906. 1922 | Whitman: Genesis of the Ores of the Cobalt District 285 of water under atmospheric pressure which will be absorbed by gran- ites, diabases, and gabbros is equal to from one ninetieth to one one- hundred-and-tenth of the volume of the rock, and that this ratio would be sufficient to bring the water in contact with only from 1 to 15 per eent of the leachable ore material contained. It would therefore be very difficult for the descending water to leach any significant metallic content from any formation along its deeper course, no matter how hot and chemically potent it might be. It has been impossible in these few paragraphs to do full justice to both of these views of eminent disputants; but I trust no injustice has been done in thus partially quoting them. They seem in the main to agree that the circulation of ground water must be chiefly and almost exclusively through fissure conduits; for its circulation is excluded from the rock pores, in which it is generally admitted to be present in a state of virtual stagnation, by the influence of adhesion and the loss of head energy through friction in the capillary and sub- capillary spaces of most firm rocks, increased mobility due to heat notwithstanding. Partisans on both sides have indicated their belief that the mobility of fluids in small pore spaces may be greatly increased by heat; but none of them makes a strong point of it nor mentions the fact that in the passage of any fluid, no matter how highly heated, through eapil- lary and subeapillary openings, its progress would be so slow that it could not be presumed to carry heat above that of the rocks through which it is passing. In fact, its initial pressure would probably be converted by friction into heat and thus lost to the surrounding rock. In spite of this fact both schools conceive water circulation to be the principal agency by which the ore materials are transported and deposited, apparently overlooking the fact that crustification deposits are in the minority, most ore bodies being due to replacement and impregnation of wall rocks. On the hypothesis of deposition from cireulating solutions they are obliged to interpret metasomatie deposits as due to the passage of immense volumes of dilute mineral waters through the pore spaces of the wall rocks, from which the disputants have excluded themselves by their own arguments. If a fissure too narrow to exhibit the phenomena of crustification becomes sealed in - the first stages of vein formation, as must be the case since the major circulation and easiest deposition would be along the open channel rather than in its walls, why should the mineral-bearing solutions thereafter prefer to circulate along its frozen and irregular walls 286 University of Califorma Publications in Geology [Vou. 18 rather than elsewhere through the rock, where the pore spaces are just as large and the impediments no greater? One school has argued that meteoric water would have great diffi- culty in attaining any but a very weak concentration in metalliferous minerals before reaching the vicinity of a freshly intruded igneous mass, and that it would also have difficulty in approaching the latter through the rock pores to absorb further quantities of mineral, on account of the heat present. On the other hand the opposed school has indicated that meteoric waters could pass through rock pores as well as magmatic waters, that they could issue hot from fissures in the walls and through the interior of an igneous mass on an equal footing with juvenile waters; and as pointed out by Lawson with par- ticular strength in the paper above referred to, the idea that juvenile mineral-bearing waters may issue in quantity from a marginally crystallized magma is weak in that it assumes the restraint of the magmatic waters from escaping until the last stage of segregation when the pore spaces of the erystalline margins would offer a serious barrier to its escape. R. A. Daly in his book, ‘‘Igneous Rocks and Their Origin,’’? makes the strong point that the long preservation of the heat and life of voleanoes is most easily interpreted as being due to the continual migration to the vent, of masses of gas-rich magma from all parts of the fluid reservoir beneath. These partial segregations of volatile con- stituents of the mother-magma occur here and there through its mass, or along its periphery, and by virtue of the lightness imparted to the portions of magma in which they are occluded, these rise to the mar- gins of the reservoir, drift along its roof to the extrance of the vent, and thence rise to its crater where they escape by explosion or quiet bubbling according to the concentrations of gas in them. On this basis it can be easily understood that the great quantities of water given off as steam at volcanic vents is misleading as to the proportion of volatile material contained even in hydrous magmas. The flow of lava from a vent might thus represent merely the escape of the masses of convected magma which served as the vehicles for segregations of magmatic gases. From other considerations advanced in Daly’s book it is also easy to understand that a magma which comes to rest beneath the surface might be relatively deficient in volatile materials, since if these were present magmatic ‘‘blow-piping’’ would have taken place in a ‘‘eupola’’ above the mass, fluxing and stoping a passage for the ascent of the magma to the surface. These considerations 1922] Whitman: Genesis of the Ores of the Cobalt District 287 must materially detract from the weight of the argument that volcanic phenomena indicate the presence of large quantities of water in magmas, and that batholithic or laccolithic masses may be presumed to exhale considerable quantities of it either before or after crystal- lizing. The phenomena of aureoles about igneous masses and of pegmatitice offshoots are usually interpreted as indicating the escape of juvenile waters from the magma. Some mineral springs may be placed in the same class of evidence. In mineral springs we have to account for mineral, heat, and water. Lindgren indicates in the above quotations his suspicion that vadose water may greatly augment the volume of such springs; and Lawson points out convincingly that such springs may not only be augmented by additions of vadose water, but that almost the entire volume may be meteoric, having passed through fissures in the igneous mass itself, arriving there through fissure con- duits from distant sources. All parties agree that the heat and mineral content may be of igneous origin; but that argues nothing relative to the passage of large quantities of juvenile, or of meteoric water either, for that matter, through rock pores. Even pegmatitic and pneumatolitic phenomena argue nothing as to volumes of water. They merely indicate transfers of material. Their transitions in min- eral content and various other evidences point strongly to a fluid medium of transfer, but neither to its volume nor to the duration of the process of dike and vein formation. The dikes appear in many cases to occupy fissures, but in others there is a vague transition from pegmatite to mother rock. The material may have been expelled from the igneous source in a single short interval, along a fissure; and the excretion may have been a very rich liquor of comparatively small volume. In any case there is no sound evidence of long continuance of the process, nor of the issuance of large quantities of water such as would be implied in the idea that these phenomena were connected with hot springs. The same holds for aureole phenomena. The assumption of large emanations of water is unwarranted. There may be a way of understanding the migration of material without recourse to the postulation either of the escape of considerable quan- tities of water from an igneous mass or of its passage through rock pores. Crustified veins may be regarded as good evidence of the passage of large volumes of hot mineral-bearing waters through open chan- nels, issuing at the surface as mineral spring's; but here as in the case 288 University of California Publications in Geology [Vou. 138 of mineral springs in general the waters are probably dilute and of meteoric origin. At any rate it does not follow that the same sort of solutions circulated through the rock pores to produce metasomatie deposits. These latter phenomena belong in an entirely different category. When a fissure becomes sealed by a mineral vein, and the vein continues to grow by marginal accretion, whatever conditions may have existed there to direct the flow of mineral-bearing solutions, they have been obliterated by the freezing of the vein to its walls, and its penetration into them. After that stage is reached the hypothetical waters are as free to move through the pores of the country rock in all upward directions as along the sides of the sealed fissure. There is no directive foree in hydrostatic pressure. But if instead of moving waters, we assume the means of mineral transportation to be the force of diffusion, driving migrant ions along the capillary and subeapillary passages of the rock, then precipitation will be a directive force capable of compelling the limitation of the diffusing of the metalliferous ions to the shortest available paths leading to the seats of deposition. The feasibility of that process and its application to vein genesis at Cobalt, I will attempt to make clear in the succeeding paragraphs. GENERAL Roue or Dirrusion IN VEIN GENESIS In approaching the subject of geological diffusion the first ques- tion to be met is: How is diffiusion through large masses of rock to be reconciled with our conception of the processes of geochemistry ? High heat and pressure are of course involved, but we are very apt, on account of our petty habits, to overlook the most important factor, namely, that of time. In considering whether concentrations of mineral have been effected chiefly by the mechanical circulation of solutions or by the diffusion of solutes through relatively stagnant solutions, one finds it easier to see efficacy in flowing ground water than in the tedious slowness and seeming weakness of diffusion. Forty thousand years is the time estimated by some authorities since the continental glacier disappeared from Ontario, yet the glaciated sur- face in many spots still retains its polish. Vastly larger figures are used to represent the duration of the Pleistocene period; but that period, in its entirety, is short as compared with other periods. If diffusion is a slow and weak process, it might nevertheless, in the long 1922] Whitman: Genesis of the Ores of the Cobalt District 289 span of time at the disposal of the genetic processes operative at Cobalt, have accomplished surprising results. The reconciliation of our notions to the idea that diffusion can produce large ore bodies must necessarily center about an analysis of the mechanism of diffusion, and also about a serutiny of rock media as sites for its operation. Whatever may be the intimate nature of the phenomena their general characters are familiar to everyone. Osmosis may be looked upon as a tendency of water or any solvent to mingle to the maximum with a solute, while diffusion may be looked upon as the reciprocal tendency of a solute to become equally dis- tributed throughout a solvent. R. E. Liesegang?® has pointed out that a large molecule behaves in a manner intermediate between a colloidal particle and an ion, diffusing with great slowness against gravity, while an ion diffuses with comparative rapidity. It appears that diffusion is roughly inversely proportional to the size of molecules and ions, and that dissociation is proportional to heat and pressure. Soret has also shown that diffusion is proportional to temperature ; while Fick has shown that the rate of diffusion is proportional to con- centration. G. F. Becker,’® applying Fick’s law mathematically, has derived some useful figures showing the distance covered by a diffus- ing salt in a given time. He says: In ‘‘linear’’ motion as defined by Fourier the subject of motion, or the ‘‘quantity’’ as Lord Kelvin calls it, varies only in one direction; in other words, it remains uniform at all points in any one plane at right angles to this diree- OD. ven aes For quantities obeying the law of diffusion the differential equation is eC ee Here v is the quantity, t the time, 2 the distance from the plane of contact between the subject of diffusion and the medium into which it diffuses, and k is the ‘‘diffusivity’’ assumed to be constant. The equation may be expressed by the statement that the time rate of change of quality is proportional to the space rate of the space rate of change of quality. .... The quality at any distance measured perpendicularly to the initial plane is then proportional to the area of the ‘‘probability curve’’ taken between certain limits. .... If the acces- sible tables have the usual form, it is only necessary to write the equation as follows: v 2 f° e 1g fet dy oO x In this equation ec represents initial concentration, and q—= Sue the least laborious method is to assume q at some tabulated even value, find # or ¢ from the first of the above equations and v from the second. 15 Geologische Diffusionen, p. 5. See also Wolfgang Ostwald, Handbook of colloidal chemistry. 16 Note on computing diffusion, Am. Jour. Sci., ser. 4, vol. 3, art. 25. 290 University of California Publications in Geology [Vou 13 Pointing out the laboriousness of computation from this equation as it stands he then undertakes its simplification. He says: The abscissa of the probability curve is not the natural independent variable for calculating diffusions. Greatly preferable is the quantity — Bo-oe 6 What is needed to facilitate computations of diffusion in a neat form, such as will not require diagrams to render the relations clear, is a table in which q, or better 2q, is expressed in the terms of v/c. Such a table is given below, but only in skeleton for intervals of v/c of .05..... Knowing 2q for a stated value of v/e the value of x in centimeters follows easily from the equation, = 2qVv kt. .... The values of 2q are given in part because they are the distances in centi- meters after the lapse of one particular time, that, namely, which is the reciprocal of the diffusivity. Thus in the case of salt with a diffusivity of .00001, after a lapse of 100,000 seconds, or some 28 hours, kt=1 and 2q represents the distance answering to u/c. In computing the table referred to, his value for the diffusivity of salt, k = .00001, refers to a concentration of 0.14785 gms. per cubic em. at a temperature of 7.7°, then for the dilution of v/c—0.5 per cent he finds that in 100,000 years salt would diffuse a distance of 731 feet. In rock media water must be considered as dispersed in films through the pore spaces, and a diffusing substance would therefore have to travel a relatively great distance to obtain only slight dilution. The tendeney would probably be for it to move more rapidly through space, but this would be to some extent offset by the tortuousness of its path. In the face of these considerations the evaluation of the rate of diffusion can not be greatly assisted by mathematical calculation, but must depend upon experimentation. This, however, is a difficult matter, since the duplication of geological conditions in the laboratory would be very dubious, especially in view of the necessary magnitude of the time factor. It is therefore necessary for the present to depend chiefly upon the results obtained in nature’s laboratory, knowing that diffusion must oceur wherever solute and solvent are in contact, and bearing in mind the quantitative results obtained by G. F. Becker for diffusion in a homogeneous and concentrated solvent. In the dispersion of a solute through the ground water filling the pore spaces of rock, diffusion can not be supposed to operate alone. Osmosis would undoubtedly play an important part in many instances. For example, suppose that a solute has obtained a fair degree of con- centration in a rock chamber, either by diffusion or by convection, and the surrounding rock is saturated with comparatively pure ground water. If the pore spaces of the chamber walls are too small to per- mit the passage of the ions of solute, and yet are large enough to 1922] Whitman: Genesis of the Ores of the Cobalt District 291 permit water to pass, then, due to the tendency of water to diffuse into the solution, an endosmotie pressure will be built up, which may reach a magnitude of several atmospheres. Now, if passages exist in the chamber walls, which, while not large enough to permit the free passage of the solute ions actuated by diffusion, are, nevertheless, large enough to permit them to be dragged through by a current of water, then, when the endosmotic pressure reaches a certain point, some of the solution will leak out into the wall rock. In this manner, local convection under a high osmotic head may be presumed to assist in the dispersion of the solute. Probably in actuality the process would not occur in stages, but osmotie pressure would be constantly cooper- ating with diffusion, local obstructions to diffusion being frequently overcome by the operation of osmosis. Fick’s law that the rate of diffusion is proportional to the concen- tration of the solute leads to the recognition of a diffusion gradient relating concentration to the distance migrated in any given interval. With such a gradient in mind it is easy to realize that after a consider- able time a diffusing salt will have established a concentration gradient such that its further migration will be at a very slow rate. However, the moment the solution becomes impoverished in the solute at any given point within the gradient, the gradient is at once steepened. In this manner a point of precipitation within a diffusion gradient not only causes the migration of solute particles to be directed toward that point from all parts of the solution, but also accelerates diffusion in that direction, and accelerates dissolution at the source of the solute if that is a dissolving substanee. Thus, if there are within a solution a point of dissolution and a point of precipitation, there will be a directed flow of matter from the former to the latter, both dissolution and diffusion being accelerated by the presence of the precipitant. In the application of the principles of diffusion to earth phenomena, it becomes necessary to consider the effects of heat and pressure upon solubility, dissociation, diffusion, and precipitation. It is somewhat hazardous to assume that the phenomena and the laws apparently governing them within the narrow field of human observation continue unaltered into the inaccessible regions where certain conditions are known to be different to an unknown extent. The recognition and projection of tendencies, however, is legitimate within certain limi- tations; and in that sense it is probably safe to say that heat and pressure tend to produce fortuity, while cold tends to produce differ- entiation, discreteness, and order. Solubility and dissociation are in 292 University of Califorima Publications in Geology [Vou. 18 general increased by pressure and heat, and valency is reduced; diffusion and gas expansion are also increased; and as depth increases there is probably an increasing tendency for one substance to mingle with another, water permeating everything, and every substance dis- solving in water to extents unknown within the horizon of observation. There is an increasing tendency for dissolved substances to ionize, and for ions to still further dissociate, every substance thus tending toward reduction to the atomic state, maximum dispersion and commingling. On the other hand as the surface is neared there must be the reverse of these tendencies, valency increasing, ions becoming more complex, solubility and diffusion diminishing. In the depths the tendency must be for reactions to oceur in such a manner as will result in the ereatest economy of space and absorption of heat; therefore, where erystalliza- tion is occurring the molecules will be the most complex ones possible, the paucity and largeness of individuals being most economical of space; but as the surface is approached there must be the reverse tendency, namely, for simpler molecules to form, or for the more com- plex ones to become unstable and to break down. Examples of this are seen in the complexity of the feldspars and pyroxenes, which are unstable at the surface and weather easily, saussuritization and uralitization often taking place some distance below the surface. The intimation above, that water may permeate everything in the depths, requires explanation. I venture this as a probability partly on the basis of theory, and partly on the evidence of the microscope, where surface alterations affect such minerals as feldspar, for instance, at some distance back from cleavages, a diminishing cloudiness being visible in the unfractured and uncleaved mineral within its inter- molecular space at a distance from any visible opening. Ions evi- dently enter and leave those intermolecular regions; and water mole- cules being among the smallest, probably smaller than the ions in question, they could as easily diffuse into that region as the other substances could diffuse out. If the intermolecular space of rock minerals is accessible to water it must be assumed present. Perhaps the migration of the mineral ions might even be taken as an evidence of the presence of water, since it constitutes a good medium for dif- fusion; and the ions of mineral matter could not be supposed to have moved away by any other process. The fact that such hypothetical water does not show itself by reactions with the minerals is no evi- dence against its presence; since whether the minerals are of igneous or aqueous origin they were probably formed or aggregated in its presence and are stable there under the conditions of the depths. 1922] Whitman: Genesis of the Ores of the Cobalt District 293 As soon as shallower depths are reached by erosion, such that hydra- tion becomes stable, then chlorite, amphibole, serpentine, etc., are formed as a consequence of the presence of the intermolecular water. Or if the rock finds itself in an oxidizing environment before such change can occur, oxygen may diffuse inte the crystal substances through the water which has always been in them, perhaps accom- panied by carbon dioxide, and thus produce alterations more intense along the mineral cleavages and diminishing away from them. With this idea, the fact of fluid inclusions in igneous minerals is In no way incompatible, since such a phenomenon would be'interpreted merely as a case where the fluid was in excess of the capacity of the inter- molecular space of the minerals to accommodate it, thus compelling its segregation. Water, should it exist in those situations, could not leave them. It would be imprisoned there. Such water as might exist in cleavages and fractures of minerals, as well as water in the rock fractures, must be supposed to be a residuum of segregated magmatic water, or, more probably, meteoric water which has found its way thither by the influence of gravity or capillarity, which forces, according to Van Hise, Posepny, Lawson, Lindgren, Kemp, and others, are adequate to accom- plish that result within the zone of fracture, and perhaps even deeper. If diffusion is a considerable factor in geo-chemical processes, it must have many phenomena standing to its credit; but the existence of a phenomenon is one thing, and the recognition of it another. The mere mention of certain of those phenomena, however, will probably suffice for their acceptance without the necessity of argument. In this category I propose such phenomena as the (1) occurrence of amygdules in vesicular lavas, (2) pseudomorphism, in which case the moleclues of one substance find their way into the interior of another, after replacing its outer portions, and the molecules of the original mineral find their way out, the passage of both being through the pore spaces, or rather, through the intermolecular space of a solid mineral substance, (3) the uniform salinity of the oeean,** (4) the remarkably uniform composition of magmas, and particularly the uniform dis- tribution in them, of silica, iron, alumina, lime, magnesia, and the alkalis. In this last case, in spite of the infinite variations of compo- sition of even such fundamental magmas as basalt, their general uni- formity is probably more remarkable than their minor variations. 17 This matter is ably discussed by R. E. Liesegang in his excellent book referred to above. He also discusses a number of other phenomena, important among which is the banding of agates. 294 University of California Publications in Geology [Vou.18 Hoping to throw some experimental light upon the problem, I sought the help of the laboratory with the following results: A hole one inch in diameter and three inches deep was bored in a block of coarsely crystalline marble eight inches long and about three inches in average cross-section. The block was then suspended in a steam chest and for two weeks subjected to a steam pressure of 60 lbs. for about nine hours per day, the steam being shut off at night. At the end of that time it was assumed that the alternations of pressure had induced the saturation of the rock with water. The hole was then about half filled with commercial sodium sulphide satu- rated and covered with water; a cork was inserted; and the cork and rock surface for an inch or two about the hole were covered over with several successive layers of a hot cement consisting of resin and beeswax. The rock was then placed, cork up, in a battery jar on a layer of pure beach sand about an inch and one-half thick. A strong solution of lead acetate in tap water was poured into the jar about the rock until it reached nearly to the cement on the top of the block. In order to exclude the air and other impurities from the jar, a layer of paraffin nearly one-quarter of an inch thick was poured over the surface of the acetate solution so that it made a firm union with the jar on the one hand and the rock on the other. This accomplished, the cemented top of the marble block projected above the paraffin seal, and was exposed to the air in such a manner that any capillary leakage of the sodium solution under the cement would be evaporated before it could reach the lead acetate solution beneath the paraffin seal. When the lead acetate solution was made up with tap water a white precipitate at once formed, due perhaps to the presence of car- bonie acid or chlorine in the water; but this soon settled making a white layer over the sand and leaving a clear solution of lead acetate above. Three weeks elapsed without any change being noted within the jar, but in the middle of the fourth week it was noted that the sand was becoming dark colored. Not believing it possible that the sodium sulphide in the cell could diffuse out in such a short time, even though the cell wall where thinnest was an inch thick, I did not visit the experiment for several days thereafter. When next I observed the jar I found the sand quite dark gray, and even black in places, and a pronounced black precipitate upon its surface, the white layer, which was originally there, being apparently much reduced. Fearing a leak had developed somewhere, I broke the paraffin seal and with- drew the marble block. A careful inspection showed that no leak 1922 ] Whitman: Genesis of the Ores of the Cobalt District 295 existed. A strong odor of H,S came from the jar when I withdrew the block; and I had in its presence an obvious proof that sulphur had found its way from the interior of the cell through the pores of the rock into the acetate solution. I washed and tested the black precipi- tate and found it to contain sulphur. As the former acetate solution in the jar now contained no lead, I was forced to the conclusion that all the lead originally introduced had been precipitated as sulphide. Still fearing a leakage somewhere, I broke the cement seal and removed the cork from the cell, but while the cork was wet the cement was not only dry where it had been in contact with the rock, but frag- ments of rock came away with it, testifying to the firmness with which it had gripped the surface. Upon breaking the marble block to bits in search of discolored fractures, I found it to be moist, but to contain no visible fractures nor discolorations such as must have been found had there been any passages larger than the ealcite cleavages through which the acetate could have entered the rock to meet the sulphide. The conclusion is inescapable that at least the sulphur of the sodium sulphide had passed through one inch of rock in thirty days. Mopr or GENESIS OF VEINS AT CoBALT BY DIFFUSION Inception of diffusion—tInasmuch as segregation of the diabase did not extend beyond the most rudimentary stage, and the margins of the mass were chilled and impervious long before the magma had ceased to flow, it must be supposed that, if ore materials were con- tained in it, they were entrapped there. Having had no time nor opportunity to segregate they must have remained in a dispersed con- dition, probably being imprisoned, perhaps along crystal boundaries or as mineral inclusions; or, more probably, as components of com- plex molecules, either replacing or accompaning the essential atoms of rock-forming minerals. The minerals which thus were foreed to accommodate the ore materials in a state which must necessarily rapidly become unstable, may have been the feldspars and pyroxenes. At any rate, such is my supposition; and the substances of this sort with which we are concerned were sulphur, arsenic, antimony, cobalt, nickel, silver, iron, bismuth, lead, and copper. Mercury and other substances may also have been present, but for the present. purpose they may be ignored, since they were very minor constituents of the ores. The magma, at some time after the erystallization, but while still hot, was deformed and fractured, and penetrated by the ground water. 296 University of California Publications in Geology [Vou. 138 While this process was in progress, magmatic juices, probably in small quantity, carried a little aplitic and pegmatitic material into the first fractures formed, and with it, small quantities of ore material. This, however, may be passed by for more significant processes, since these indications of segregation are not inconsistent with what has already been said nor with what is to follow; it is mentioned in this place to give ground for the supposition that in the saturation of the diabase with a fluid medium for the operation of diffusion, the magmatic juices, by largely uniting with the ground water, may be regarded as having made a material contribution. When the ground water arrived it may have been saturated with such dissolved substances as lime and magnesium carbonates, silica, alkaline carbonates, and a certain amount of sulphates and sulphides. It must also be supposed that the magmatic juices contributed a cer- tain amount of solvent substances. If it is admitted that sulphurous acid and sulphur may have been present to make thiosulphates with the alkalis, or that the 8,0, ion may have been produced by such a reaction as: S, + H,O =S8,0, + 3H,8, then what Roscoe and Schorlemer have to say about thiosulphates'® will be of interest : Thiosulphates exhibit a great tendency to form double salts; those of the thiosulphates insoluble in water are found to dissolve in an aqueous solution of sodium thiosulphate, which also has the power of dissolving other insoluble salts such as silver chloride, silver bromide, silver iodide, lead iodide, lead sulphate, calcium sulphate, etc., thus: Na} Na] = S. = S.O. y Na $.0;.+ AgCl Ag 8.0, + NaCl Na.8,0, + NiCl, + H,O = H,SO, + NiS + 2NaCl Na.8,0, + CoCl, + H.O= H, SO, + CoS + 2NaCl. The same authors make reference in another place’® to the complex nickel silicates, rewdanskite (Ni, Fe, Mg)3Si,0, + 2H,O and garnier- ite, 2(Ni, Mg).Si,O,, + 3H,O. It may be useful to bear these in mind in connection with the idea of the impurities assumed for the essential minerals of the diabase. The rdle of arsenic and antimony in these reactions can probably be safely assumed to be in many eases that of partial substitutes for sulphur. At any rate it is to be assumed that the solvent for the ore metals is a solution of sodium thiosulphate, and that the ore ele- ments, being unstable in their false positions in the pyroxenes, etc., 18 Vol. 1, p. 414. 19 Vol. 2, p. 1040. 1922 | Whitman: Genesis of the Ores of the Cobalt District 297 of the diabase, leave them and diffuse to the nearest cleavage, crystal boundary, or fracture, where they enter into the composition of the highly dissociated equivalent of such complex molecules as :°° Co.8,0, . Na.S.O0,.H.O and Ag,S.0, . Na.S.O, . H,0. Migration —At this point the mechanism of diffusion may be supposed to begin in its general geological manner. It must be recalled here that whatever may have been the span of geological time in which these operations were going on, they began with a tempera- ture in the diabase and its immediate neighborhood but little below the temperature of solidification ; and the heat emanated was not only the superheat of the magma, but also the specific heat of the minerals which erystallized from it; while there was a molar pressure due to several thousand feet of overburden and the cooling contraction of the igneous mass and its wall rocks. There must also have been a slow-acting but none the less effective hydrostatic pressure upon all free water in fractures and pore spaces, due to a head cf several thousand feet and to a high vapor pressure due to the temperature. The solvent was probably highly superheated either as hquid or gas, and had extreme power of penetration. It was not only saturated with all substances with which it came in contact, but was probably heavily charged with them, and carried also the ore materials in fairly strong concentration. All its solutes were highly dissociated and reduced in valency to their lowest terms, and at the same time highly charged with free energy. This was the result not only of high tem- perature and pressure, but also results of the catalytic influence of such solvent agencies as thiosulphates and alkaline carbonates, or sulphides. Since the solvent in which the ore ions tend to diffuse is not en masse but is disposed in films, the ions would have to travel far in order to attain an appreciable attenuation. This form of the medium of diffusion would therefore greatly increase the distance traveled by an ion in a given time, the diffusion gradient being in no way affected, since the gradient refers to the amount of solution traversed for a given change in concentration. As pointed out by Daly*! the heat conductivity of rocks is very low. The rate of radiation from an intrusive mass must fall off rapidly after the first extreme differences have been dissipated by 20 Abegg’, Handbuch der anorganischen Chemie, Ableitung 1, p. 714. 21 Tgneous rocks and their origin, p. 198. 298 University of California Publications in Geology [Vou. 18 the emanation of the superheat of the magma, and the heat gradient has become relatively flat. It may reasonably be expected, therefore, that although the diabase and its neighborhood did not long remain at their initial temperature, the diabase itself must have remained hot for a considerable length of time. In the course of that time the ore materials must be conceived to have found their way from mineral cleavage to. crystal boundary, thence to shear joint and flat fault, and to the flatly inclined diabase and Keewatin contacts where shearing was chiefly concentrated, and thence to spht joimt and steep fault, where deposition occurred. At certain points here and there the journey of the ore ions may have been hastened by water circulation, but probably in general that was a negligible factor in their dispersion. Finally, a given ion may be supposed to have arrived at a point in the adjacent conglomerate where it was removed from the solution by precipitation. At once the neighboring ions, being relieved of its active presence, moved to take its place in the solution and were themselves precipitated in the same manner. As precipitation progressed at that point, thus impoverish- ing the neighboring solution, the diffusion gradient was steepened there, and a general migration to the point occurred throughout a larger and larger region about, until it finally extended to the source of the ions in the diabase, reduced their concentration there, and thus hastened the solution of others. In this manner solution and diffusion were accelerated throughout a considerable space about the point of precipitation, and the movement of ions from their source became increasingly direct to the point of precipitation. As one point of pre- cipitation after another was established, the entire locality and mass of diabase became impoverished in ore ions, and these ions were ex- clusively concentrated in the veins. Miller and Knight? made many careful analyses of the Nipissing diabase and found it to contain no silver. If the mother-magma of the diabase had been the source of the ores, surely some silver should be found in the diabase. One might say, if the visible diabase itself were the source of the ores, why does it show no silver? The answer is, that if the silver came from the diabase it could not still be in the place from which it came. One might object to this that a residiuum of silver should remain at its source; but that would imply that the extraction was only partial. What right have we to assume that? If some ageney was able to extract and remove the silver, why should it 22 Ont. Bur. Mines, Report, vol. 19, pt. 2. 1922 ] Whitman: Genesis of the Ores of the Cobalt District 299 not have removed all there was, and have deposited it entirely in the veins? My assistant, W. L. Whitehead, proposed a comparison of the production of the mines with the calculated volume of diabase which is presumed to have contributed to them. My figures for these com- putations follow. In making the computations I assume that the aver- age distance from the point of origin to the point of deposition of a particle of ore was 500 feet, and that as much ore was deposited along one margin of the sheet as along the other. This assumption necessitated the estimation of the volume and weight of a sheet of diabase 500 feet thick over or under each group of veins, and sur- rounding it for aradius of not more than 500 feet, upon the assumption of a thickness of 1000 feet for the total diabase mass. Many errors are undoubtedly represented by the resulting figures; but I have tried to throw all non-estimable errors onto the side of excessive richness in silver on the part of the diabase. The computations assume the weight of the diabase to be 187 pounds per cubic foot. The production of silver is taken as being 314,391,494 ounces from the years 1904 to 1919 inclusive, as indicated by the government reports; and the volume of diabase involved is estimated at 37,739,500,000 cubie feet, which would weigh 3,528,643,250 tons. This estimate would give a silver content of 0.089 ounces per ton of diabase, or 0.0000037 parts, or 0.00037 per cent by weight, or 0.26 gems., of silver per cubie foot of diabase. Such a silver content is not unusual inigneous rocks. In ‘‘The Data of Geo-Chemistry,’’** Clark quotes Hillebrand’s analyses of Leadville porphyries as indicating an original silver content of 0.000009 parts. The same ratio was obtained from a voleanie ash from Tunguragua, while an ash from Cotopaxi contained 0.0000119 parts of silver. J. B. Harrison is also reported to have found in igneous rocks from British Guiana a silver content of 0.0000016. Perhaps the reason why the original silver content was found in these rocks is that they did not contain also solvents for the silver, and whatever ground water may have reached them was deficient in like manner. Deposition.—Sphit joints have already been discussed, and it has been pointed out that those in which ore was deposited were the ones the walls of which were the most free from lateral compression, being under longitudinal compressive stress. Attention was also drawn to a remarkable relationship existing between the mineralogical contents of veins and their dips. The arrangement of the mineral constituents 23U. S. G. S., Bull. 148. 300 University of Califorma Publications in Geology (Vou. 18 was stated to be fan-shaped, the richest ore being at the center of the fan where the midpoint of the vein rested upon a strong shear joint or flat fault. Briefly, all these and similar phenomena appear to find their explanation in the stresses existing in the vein walls during vein deposition, the richness of the ore deposited being inversely propor- tional to the later compressive stress in the walls. In the description of the veins I attempted to show evidence indicating that they were due to the metasomatic replacement of the wall rocks. I regard it as obvious that the replacement was grain-for-grain in the sense of volume-for-volume and not molecule-for-molecule, since the veins in mineral character, structure, and all other respects are the same in diabase, Keewatin, and Cobalt Series, and the pebbles in the Cobalt conglomerates consist of virtually every sort of igneous and _ sedi- mentary rock, and yet are replaced indiscriminately and in the same manner by smaltite and its associates. The even tabular dimensions of many veins, and the rare and anomalous occurrence of crustification as against the general massive character of the vein matter must be regarded as a priori evidence that the veins do not represent chamber fillings, since such chambers could not have existed under the conditions of origin of these fissures. In other cases the gradual transition between solid vein, vein with band-like inclusions of wall rock, unchanged in orientation, walls with parallel veinlets, and slightly altered walls, would seem to constitute equivocal evidence of replacement. It seems clear, largely upon the basis of the vein characteristics already described, that a vein grew outward from the original narrow fissure as a starting point. It makes no difference, however, if one prefers to consider that the fissure, tight as it must always have been, remained open until the last, and then was sealed in such a manner as to show a total absence of comb structure. In either case the vein minerals were deposited in the midst of firm rock, and must have traversed either firm ore or firm rock in order to be deposited on the vein margins. At this point, lest it might be thought that the last step in the delivery of the ore to its destination was accomplished by passage through colloidal vein matter, I must object that although the pres- ence of colloids is often demonstrable or very plausible at or near the earth’s surface, or in the vadose region, I believe the opinion of chem- ists will support me in denying such possibilities in the depths, where there is considerable heat for long periods of time, and particularly 1922] Whitman: Genesis of the Ores of the Cobalt District 301 in cases of metasomatism, where precipitation is not hasty but is very deliberate, since under such conditions colloidal particles, even though formed, would have ample opportunity to undergo re-solution and re-deposition as erystalloids, according to the principles of crystal growth set forth by Wm. Ostwald.** Coming now to a consideration of the conditions existing in the vein walls at a point where deposition of ore is about to occur, we must recall that the fissure in question is under longitudinal compres- sive stress and consequent lateral tension. A given wall particle is under differential stress, and is therefore several times more soluble than it would be otherwise, its solubility being proportional to the stress difference. At a point, then, midway between the ends of a spht joint, and where it bottoms on a strong shear joint or flat fault, the stress difference is the greatest. That is the point, as has already been indicated, where the richest ore has been deposited. There the wall rock tends most strongly to pass into solution. The fissure and the pore spaces of the rock are saturated with ore- bearing solution; and it may be assumed that all solutes are at the saturation point. It is assumed also that one of these solutes is silver sulphide, the solvent being a solution of sodium thiosulphate. The exact mechanism of replacement which takes place under these con- ditions can not yet be stated. However, were the replacement to be by chemical substitution, volume changes must occur and contraction or expansion would be evidenced by vugs in the vein or strain in the walls; but both these are absent. The replacement clearly is a matter of relative solubilities and of volume-for-volume substitution. It would seem that in the reaction the wall rock on passing into solution, as a result of the differential stress affecting it, must absorb energy, which assists the precipitation of metalliferous substanees in which the solution is saturated. At the same time the solution of the wall- rock silicates probably consumes a certain amount of the solvent of the ore material, thus adding another cause for its precipitation; but the amount leaving the solution is just enough to fill the space vacated by the silicate, as otherwise a back-pressure might be established, so great as to inhibit further reaction. The selective precipitation of ore and gangue minerals may have been governed by the fact that precipitating crystalloids exert a pressure due to the force of erystallization, and the substance with 24 Wm. Ostwald, The scientific foundations of analytical chemistry, ed. 1900, p. 22. 302 University of California Publications in Geology [Vou 18 the greatest force of crystallization, or with the largest volume change in crystallizing from solution, would be precipitated where the wall pressure is least, and vice versa. This would account for the preference of precipitating dolomite, which has a small atomic volume, for the marginal region of the fissure where the wall pressure is great- est. In the above reaction AgS is shown as the substance precipitated as a silver salt. The reaction, however, like the whole picture here presented, is intended merely as a similitude—a means of indicating the general sort of thing which may be presumed to have occurred. In view of the conditions of high temperature and pressure, it seems more likely that a large complex molecule was deposited as the ore molecule, containing silver, cobalt, nickel, arsenic and sulphur—a mole- cule stable only under those peculiar conditions, and unstable under conditions of less pressure. Subsequent molecular rearrangement.—The most complex mole- cules to be found in the present ores are oceasional sulpho-salts of silver, such as proustite, ete. The metals usually occur native or in binary compounds. In the mineral mixtures which constitute the present ores evidence was sought by Miller and Knight for paragenic sequences, but the evidence of the veins of many mines seems to show contradictory sequences. My conclusion is that no uniform set of sequences exists. Miller indicates his belief in a period of calcite and silver deposition subsequent to that of the arsenides; but I find silver in wire form lying within massive unfractured smaltite and niccolite, as if not having come after the arsenides but with them. Another and perhaps more common phenomenon is the occurrence of spherical pellets of silver, perhaps two millimeters in diameter, in the center of pellets of niccolite, which are themselves the cores of pellets of smaltite. The arsenides are never found replacing silver, nor is dolomite or calcite found replacing either silver or arsenide. The relationships are always the reverse; but this may be accounted for much better on the basis of relative forces of crystallization than of absolute time sequence. The disorderly mineral relations obtaining in these ores seem to find a more consistent explanation in the rearrangement of vein con- stituents due to the breaking down of the original complex carbonate and sulpho molecules as the pressure was reduced by the approach of the surface due to erosion. A good line of evidence bearing upon this point is found in the fact that in wall fractures uncemented by typical vein matter, severing the veins, and obviously of later origin, 1922] Whitman: Genesis of the Ores of the Cobalt District 303 are found crusts, often beautifully crystallized, consisting of proustite or argentite, or dyscrasite, or perhaps native bismuth, these crystalline masses coalescing with and blending imperceptibly into typical ore in the adjacent veins. CONCLUSION In this account and discussion of the geology at Cobalt the two principal points which I have intended to make are that the fissures in which the ores were deposited were not cooling cracks in the strict sense, but were joints developed as a result of folding subsequent to the solidification of the diabase, and that the ores were derived from the diabase sheet itself, transported, and deposited chiefly through the ageney of diffusion through relatively stagnant water in the pore spaces of the rocks. The folds, which affect diabase and sediments alike, are parallel with the major structural axes of the region and also with the original undulations of the diabase sheet which transgress the sedimentary beds, these folds being indicated in the diabase by innumerable large and small surfaces of shearing parallel with the surface of folding. The vein joints are spatially related to the folds and to the faults which originated during the folding. From these relationships it is inferred that such joints are genetically related to the other deforma- tions and to external compressive stresses rather than to direct cooling shrinkage. It is immaterial, and impossible to conjecture, whether this compressive stress arose chiefly from the lateral expansive force due to the heating of the locality of the sheet, or whether it arose chiefly from the general contraction due to the cooling of the locality of the sheet, the latter having an undulating configuration, and the undulations being weak to lateral compression resulting from the con- traction of their general environment. Since all the deformations, however, are clearly of the same immediate period as those in the diabase, the conclusion seems inevitable that the diastrophiec activity followed the solidification of the igneous mass, and was of a compres- sive character. In connection with the genesis of the ores it was pointed out that the commercial veins of the whole region as well as those in other parts of northern Ontario lie exclusively within marginal zones of the Nipissing diabase extending not more than 350 feet inward and outward in the diabase and Keewatin formations, nor more than 550 304 University of Califorma Publications in Geology [Vou. 138 feet from the diabase margins in the Cobalt Series of sediments. Even the noncommercial deposits and traces of cobalt in the northern part of the provinee are clearly related to the diabase, and no occurrences are known in this whole region that are clearly related to deep fissures in controversion of this rule. These facts are taken as strong evidence that the visible diabase itself was the source of the ores. Negation was resorted to in order to exclude any supposition that the ores might have originated either through the downward circula- tion of vadose waters or through the upward circulation of juvenile or of hot meteoric waters. These matters need not, perhaps, be re- viewed here further than to recall that the principal points made in regard to ascending solutions were: (1) that the heated mineral waters of the earth, whatever their origin, are known to be very dilute, so that large volumes would be required to pass through the rock in order to produce a moderate amount of metasomatie ore; (2) that in the absence of crustification and comb structure, metasomatic veins can be supposed to have grown only by marginal accretion; (3) that the chief circulation of underground water must be through fissures, and that its passage in volume through pore spaces must be practically inhibited by the large coéfficient of friction due to the narrowness of the capillary and subeapillary openings and the tortuousness of its course; and (4) that, at least in the case of the silver ores under dis- cussion, the veins and vein walls offer no more porous courses for the passage of water than the country rock offers, and therefore there would be no directive agency to cause mineral-bearing solutions to circulate there rather than at random through the country rock. At Cobalt the chief ore production has come from beneath the diabase sheet, the veins being metasomatic replacements of the walls of cul de sac fractures. It seems far-fetched to suppose, since the diabase invaded chloritie schists which must have been saturated with ground water, that mineral-bearing solutions could have circulated downward from the diabase into the already saturated country rock in sufficient quantity and strength to have produced such metasomatic deposits in those blind fractures. Local convection currents could be supposed to have only gone round and round in a fracture of that sort without any chance of replenishing their original supply of mineral. Water circulation being practically inhibited, recourse must be had to the principle of diffusion to explain the transference and depo- sition of mineral; but slow as would be the migration of metalliferous 1922] Whitman: Genesis of the Ores of the Cobalt District 305 ions through the pore spaces of the rock, it would nevertheless be that of mineral at 100 per cent concentration; and, furthermore, it would be directed from the point of its origin to the point of deposition by the steepening of the diffusion gradient at the point where precipi- tation is going on. Time seems to be the chief obstacle in the way of accepting diffusion as a dominant agency in the genesis of metasomatic ore deposits. The ratio of its effectiveness to that of water circulation is the point in doubt. There are two forces which may be considered as tending to actuate the circulation of water through the pore spaces of rock, eapil- larity and hydrostatic head, or difference in head. Capillarity oper- ates only in the first wetting of the rock; after that hydrostatic head is the sole actuator. In the depths this can arise only from heat or the compression of rocks containing water in sufficient quantity to be squeezed out. In either case the head would have to be considerable to drive water through capillary openings for a great distance; and the propagation of that force would be so slow that the passage of large volumes of water past a certain point within a firm rock might easily take as much time as the migration, by diffusion, of an equiva- lent amount of mineral ions. This ratio of effectiveness is at present indeterminable, and must await the results of experimentation. In the meantime, however, we have some very definite chemical facts in which to find assurance that diffusion is a factor to be reckoned with. Fick, Soret, and others have made it clear that when a solute is in contact with a solvent it tends to diffuse into the solvent until equally distributed through it. The diffusion gradient consequent upon Fick’s law supplies a directive agency and a means of accelera- tion the moment precipitation begins within the field of diffusion. Its operation is slow but relentless. The force actuating the diffusion of salts has not been measured directly, but its supposed equivalent in osmotic pressure has been equated*? and measured, and found in ecer- tain instances to attain a magnitude of many atmospheres. Thus we already know that where there is water and a solute, the latter will tend to migrate through the former without cessation until equally 25 Alexander Finlay in ‘‘Osmotie pressure,’’ p. 31, states the thermodynamic equation for osmotic pressure as follows: P=p—po="o-[—loge (1—#) —%4 oF]. oO Here P=osmotie pressure, p—pressure of solution, pp pressure of solvent, =a constant depending upon the salt used, 7 —absolute temperature, V = molecular volume of solvent under standard pressure, 2—molar fraction of the solute, and a= coefficient of compressibility of the solvent. This is for concen- trated solutions. 306 University of California Publications in Geology [Vou. 13 dispersed through it; and when obstructed it will be assisted by the force of osmosis. Given the time, then, which is required for the flow of large volumes of water through a great thickness of firm rock, diffusion is a factor to be considered. The particular utility of that concept in assisting the understanding of the phenomena of vein genesis lies in the subtlety, mobility, efficiency, and vector quality of diffusion. BIBLIOGRAPHY OF THE COBALT DISTRICT, ONTARIO MILLER, W. G. 1904. Eng. and Min. Jour., vol. 76, pp. 888-890. 1904, Ont. Bur, Mines, Report, pt. 1, pp. 96-103. 1905. Jbid., pt. 2, p. 28. 1905. Abstract, Science, new ser., vol. 21, p. 221. 1906. Abstract, Geol. Soc. Am., Bull, vol. 16, pp. 581-582. 1907. Can. Min. Jour., vol. 28, pp. 7-11. 1911. Eng. and Min. Jour., vol. 92, pp. 645-649. 1913. Int. Geol. Cong., Twelfth, Guide Book No. 7, pp. 51-108. 1913. Ont. Bur. Mines, Report, vol. 19, pt. 2. 1913. Can. Min. Jour., vol. 34, pp. 87-90. ParKsS, Wm. A. 1905. Can. Geol. Surv., Summary Report, 1904, pp. 198-225. 1907. Hamilton Sei. Assoe., Jour. and Proc., No. 23. CorRKILL, E. T. 1906. Ont. Bur. Mines, Report, vol. 15, pt. 1, pp. 47-107. 1910. Ibid., Report, vol. 19, pt. 1, pp. 78-130. MACDONALD, J. A. 1906. Eng. Mag., vol. 31, pp. 406-416. BELL, ROBERT 1905. Can. Geol. Surv., Summary Report, 1905, p. 94. 1906. Can. Geol. Surv., Summary Report, 1906, pp. 110-112. 1907. Can. Min. Jour., vol. 28, pp. 246-248. CourTIs, Wm. M. 1906. Eng. and Min. Jour., vol. 82, pp. 5-6. GEORGE, H. C. 1906. Eng. and Min. Jour., vol. 82, pp. 967-968. RICKARD, T. A. 1907. Min. and Sci. Press, vol. 94, pp. 23-25. TYRRELL, J. BURR 1907. Can. Min. Jour., vol. 28, pp. 301, 303. 1908. Inst. Min. Engin., Trans., vol. 35, pt. 4, p. 488. 1912. Can. Min. Jour., vol. 33, pp. 171-172. Van Hise, Cuas. R. 1907. Abstract, Can. Min. Jour., vol. 1, no. 2. 1922 ] Whitman: Genesis of the Ores of the Cobalt District Hore, REGINALD E. 1908. Econ. Geol., vol. 3, pp. 599-610. 1908. Can. Min. Inst., Jour., vol. 11, pp. 275-286. 1908. Min. Sci. Press, vol. 97, pp. 874-876. 1909. Can. Min. Jour., vol. 30, pp. 118. 1910. Jour. Geol., vol. 18, pp. 271-278. 1910. Min. World, vol. 133, pp. 747-751. 1911. Eeon. Geol., vol. 6, pp. 51-59. 1911. Am. Inst. Min. Engin., Bull. No. 53, pp. 413-432. 1911. Can. Min. Inst., Quart. Bull., No. 17, pp. 81-105. 1911. Min. and Engin. World, vol. 35, pp. 1049-1053. 1912. Am. Inst. Min. Engin., Trans., vol. 42, pp. 480-499. 1913. Ont. Bur. Mines, Rept., vol. 19, pt. 2, pp. 145-148. 1913. Min. Mag., vol. 8, p. 43. 1913. Mex. Min. Jour., vol. 16, pp. 178-181. 1913. Eng. and Min. Jour., vol. 95, pp. 981-982. StuTGER, O. 1908. Zeitsch. prakt. Geol., pp. 16, 511. Youne, Gro. A. 1909. Can. Geol. Surv., Pub. 1085, 1909, pp. 89-91. HiceGins, Epwin 1909. Eng. and Min. Jour., vol. 87, pp. 1267-1272. CoLE, ARTHUR A. 1910. Eng. Mag., vol. 40, pp. 15-30. Emmons, 8. F. 1910. Abstract, Science, new ser., vol. 31, p. 517 (April, 1910). 307 EXPLANATION OF PLATE 15 A. Showing results of deposition in vein fissures. The white vein matter is barren calcite; the gray is silver-bearing smaltite and niccolite. B. Enlargement of right-hand vein in A showing relations of minerals more intimately. [308] UNIV, CALIF: PUBE. BULL; DEPT. GEOL, ‘Sci, [WHITMAN ] VOL 7 Ss (RE 15 ~ sitbane EXPLANATION OF PLATE 16 A, Branching vein. B. Typical vein in conglomerate showing reticulate structure. Vv NdsGh Wiser Tea slave: NING VIS VANES) [NVALIHM ] “TOA A MARSUPIAL FROM THE JOHN DAY OLIGOCENE OF LOGAN BUTTE, EASTERN OREGON ) ms BY CHESTER STOCK AnD EUSTACE L. FURLONG \ ~s National MM yer herent nace minions _ UNIVERSITY OF CALIFORNIA PRESS BERKELEY, CALIFORNIA 1922 Sciences, Puiysiblbee a and Zobleey) GEOLOGICAL SCIENCES.—Anprew C. Lawson, Editor. Price, ‘volumes volumes 8 and following, $5.00. Volumes 1-12 completed; volume 13 in me x. list of titles in volumes 1 to 7 will be sent upon request. VOLUME 8 1. Is the Boulder ‘‘Batholith’’ a Laccolith? A Problem in Ore-Genesis, by ‘And ies ©. Lia wen ys c.2--cstte cesar ote Se fh 2. Note on the Faunal Zones of the Tejon Grup, by Roy E. Dickerson ......-...----.:--+4 254 ie 3. Teeth of a Cestraciont SHEE from the Upper Triassic of Northern California, by rs Harold) C.. Bryant’ -... 2s nb er ee R 4, Bird Remains from the Pleistocene of San Pedro, California, by Loye Holmes Miller. ry 5. Tertiary Eehinoids of the Carrizo Creek Region in the Colorado Desert, by William i DoW. Wlewi -2.gc. Ss a EE wt 6. Fauna of the Martinez Eocene of California, by Roy Ernest Dickerson ..........-...-« 7. Descriptions of New Species of Fossil Mollusca from the Later Marine Neocene of California, by Bruce Martin 2.2-....-..05. 2 tt ee 8. The Tacavaaits Group near Newhall, California, by Walter A. English ...............----- 9. Ore Deposition in and near Intrusive Rocks by Meteoric Waters, oy Andrew C. \ TAA WSOD a. penctescenccscseseccertvcnseecncen-cansnesontochdecscesentieasesevet tnensit anes test teat a eee Se 3 10. The Agasoma-like Gastropods of the California Tertiary, by Walter A. Eagle ed 11. The Martinez and Tejon Eocene and Associated Formations of ne Santa Ana — Mountains, by Roy EH. Dickerson °.....5.2.000.0...24 2.0. a 12. The Occurrence of Tertiary Mammalian Remains in Northeastern Nevin by John OPEN Eesha Pe ee ON ipo te A a PRION Fe 13. Remains of Land Mammals from Marine Tertiary Beds in the Tejon Hills, Cali fornia, by John C. Merriam | <.2..-22-c22---ctciscescctcatccen doeentecctcteteeorebera tees ae eae ee 14. The Martinez Eocene and Associated Formations at Rock Creek on the Western Border of the Mohave Desert Area, by Roy E, Dickerson ...........-.-----seccsecesceereeeeeene 15. New Molluscan Species from the Martinez Eocene of Southern California, by Boy BBN DACOT SON) 2 n.2-----ees-ncicceeecesnscnnsr sued snare cee dsecetetnuctte seeps Meseat aces ce aes Oe eee es 16. A Proboscidean Tooth from the Truckee Beds of Western Nevada, by John P. 157) 1.74:)1 (0 (eee eee ee ee ecoeremen cermin Ni 17. Notes on the Copper Ores at Ely, Nevada, by Alfred R. Whitman ie 18. Skull and Dentition of the Mylodont Sloths of Rancho La Brea, by Chester Stovly 19. Tertiary Mammal Beds of Stewart and Ione Valleys in West-Central Nevada, by : ; John P. Buwalda 20. Tertiary Echinoids from the San Pablo Group of Middle California, by William S. Wie RO Wii ok sonst nnn n Sas pata Sactccennceanennganmeteeee te cen epeplouse drat neste de tenet aetna ee as ee a 21. An Occurrence of Mammalian Remains in a Pleistocene Lake Deposit at- Astor Pass, near Pyramid Lake, Nevada, by John C. Merriam ...........-------.-.---sscossessensecenene 22. The Fauna of the San Pablo Group of Middle California, by Bruce L. Clark ............ VOLUME 9 " 1. New Species of the Hipparion Group from the Pacific Coast and Great Basin Prov- . ; inces of North America, by John) ©. Merriam 2 iien onan eo cscnseencenateeececesnanenanastenereenane Ai 2. The Oceurrence of Oligocene in the Contra Costa Hills of Middle California, by : Bruce Ly, Clark -1....---..secseesceeceeeeecee sce ceenesneecnecnncnneenecnenaesneccnareacensecnecassreescinsnnmanieenneen Ji 3. The Epigene Profiles of the Desert, by Andrew C. Lawson ...........-.------.s-s--see-sensenes 4. New Horses from the Miocene and Pliocene of California, by John C. Merriam . 5. Corals from the Cretaceous and Tertiary of California and Oregon, by Jorgen | Pha! +2 C116 eee ee ee ee ee hes, a A 6. Relations of the Invertebrate to the Vertebrate Faunal Zones of the Jacalitos a Etchegoin Formations in the North Coalinga Region, California, by Jorgen | NCI MR Se Ne SR es 7. A Review of the Species Pavo californicus, by Loye Holmes Miller) 2.22" 8. The Owl Remains from Rancho La Brea, by Loye Holmes Miller ..... 9. Two Vulturid Raptors from the Pleistocene of Rancho La Brea, by They a Mer cats ecteah eh ERS ee aie 10. Notes on Capromeryx Material from the Pleistocene of Rancho La B @handler’ (2 le ea Dee ea a a ey eee a shal UNIVERSITY OF CALIFORNIA PUBLICATIONS BULLETIN OF THE DEPARTMENT OF GEOLOGICAL SCIENCES Vol. 13, No. 8, pp. 311-317, 5 figures in text May 11, 1922 A MARSUPIAL FROM THE JOHN DAY OLIGOCENE OF LOGAN BUTTE, HASTERN OREGON BY CHESTER STOCK anp EUSTACE L. FURLONG CONTENTS PAGE HTS B50 CALC GO Tap Peat ects cen se Bee wee os OP esas eee Roe et esata ees ecuecee tes test isustvelcesusdesas taseeeee 311 OC CUTE CTU peer seas a ree as ae Ee Saeed ee eee eee ses se re eeetis cased ni ote Ole, Hee Tava CRU Irlge Mn OTT) VII pa SY) wees seen ee sce cee es eee en eg ea ose Ne 312 AMO. ESS OLX 019 ie Ne Pee eer 312 IS DECI CMC ama CUCL ie cessssecs elec secs eres eee, bio ceuener tes eave eee Masser Sark ees. Lt 312 XS YSY GEA OY 0 0 ee ae a ee ee ete 313 SULT RMT Tay ce Stes ree ee SE ee sa Oe A ese ee ovens oe e cease rece ead ee 317 INTRODUCTION During the summer of 1920 a field party from the Department of Palaeontology, University of California, visited the region of Logan Butte, south of the Crooked River in eastern Oregon, and collected in the John Day Oligocene deposits. Among the specimens obtained is a small, fragmentary skull apparently belonging to the genus Pera- theriwm. An important member is thus added to the large and varied mammalian assemblage known from the John Day beds. The presence of Peratherium at Logan Butte records for the first time a marsupial in Tertiary deposits of the Great Basin Province and presumably rep- resents the latest occurrence of the genus in North America. The writers desire to express their appreciation to Mr. Gerrit S. Miller for helpful suggestions in the study of the John Day species and for the arrangement of a loan of mammal skulls from the U. S. National Museum. Drawings of the John Day material were submitted to Dr. W. K. Gregory of the American Museum of Natural History and to Mr. J. W. Gidley of the U. S. National Museum. Dr. Gregory and Mr. Walter Granger made comparisons with specimens in the American Museum and directed attention to the resemblance between 312 Unwersity of California Publications in Geology [ Vor. 13 the Oregon form and the genus Peratherium. Mr. Gidley in a letter dated June 11, 1921, also indicated the didelphid affinities of the Logan Butte specimen. Through the kind efforts of Dr. Gregory and Mr. Granger the writers were permitted to borrow materials of Pera- theriwm for comparison. OcCURRENCE The John Day Oligocene deposits occurring south of the type locality in the John Day Valley are well exposed in the drainage basin of the Crooked River southeast of Prineville. Along Camp Creek, a tributary of the Crooked River, the beds consist of voleanie ash, red- dish brown and bluish green in color, and resemble the lower and middle John Day beds in the John Day basin.t At Logan Butte, a landmark near the head of Camp Creek and approximately fifty miles southeast of Prineville, Crook County, Oregon, the green colored tuffs of the John Day, in which occur the marsupial remains here deseribed and many specimens of oreodons, are distinctly folded. The beds are overlain unconformably by a later Tertiary formation closely resembling in its lithological characters the Rattlesnake Phocene deposits of the John Day Valley. The Oligocene fauna, as represented by the collections made during the summer of 1920, has not been completely reviewed. Dr. John C. Merriam? determined the presence of three carnivores, Mesocyon brachyops Merriam, Temnocyon alti- genis Cope, and Archaclurus debilis major Merriam, from remains obtained in 1899-1900. PERATHERIUM MERRIAMI, n. sp. Type Specimen.—A fragmentary skull and lower jaw, no. 24240, Museum of Palaeontology, University of California, from the John Day Oligocene beds at Logan Butte, eastern Oregon. This species is named in honor of Dr. John C. Merriam. Specific Characters—Skull larger than in Peratherium fugax (Cope) from the White River Lower Olgocene of Colorado and smaller than in Lower Miocene species of Perathertum from Europe. The two posterior premolars of the superior dentition are relatively not so narrow as in P. fugax. M+ is more robust than the correspond- ing tooth of P. fugax. 1 Russell, I. C., Preliminary report of the geology and water resources of central Oregon, U. S. Geol. Surv. Bull. 252, 1905. 2 Merriam, J. C., Carnivora from the Tertiary formations of the John Day region, Univ. Calif. Publ. Bull. Dept. Geol., vol. 5, pp. 1-64, pls. 1-6, 1906. 1922] Stock—-Furlong: A Marsupial from the John Day Region 313 Description.—Specimen 24240 is smaller than skulls of Recent species of the South American polyprotodont genus Marmosa. The palate (fig. 1) in the John Day specimen has large fenestrae between the molar series, but the largeness of the fenestrae is in part due to a breaking away of the palatal margins. The tympanic process, which is bullate in Marmosa and formed by the alisphenoid, is as much developed in Perathertum merriami as in the former genus. In side view of skull (fig. 2), the exit of the infra-orbital canal is seen to be situated farther in front of the anterior border of the orbit than in Marmosa. In P. merrianu the distance measures 3.3 mm., while in four skulls belonging to three species of Marmosa the measurement varies from 1.8 mm. to 2.8 mm. The exit is located above the anterior end of the first molar in P. merrianr; in Marmosa it is often seen above the middle of the last premolar. In Peratheriwm fugax the facial exit of the infra-orbital canal is also situated at a greater distance from the orbit than in Marmosa. Figs. 1 and 2. Peratheriwm merriami, n. sp. Skull, no. 24240, Mus. Palae. Coll, X 2. Fig. 1, ventral view; fig. 2, lateral view. John Day beds, Logan Butte, Oregon. In Peratherium merriamé and in P. fugax the anterior border of the orbit hes above the posterior end of M2; in Marmosa the border may be situated above the middle or the front end of M+. The orbit, therefore, does not extend so far forward in the Oligocene species as in the Recent Marmosa. The anterior border of the orbit in the Recent Didelphys reaches forward to a point situated above the posterior end of M+ while the facial exit of the infra-orbital canal is located above the posterior end of P?. The zygomatic process of the squamosal in no. 24240 is relatively shorter than in skulls of Recent Marmosa. In the lower jaw the inferior border below the masseterice fossa is not deflected decidedly from that beneath the tooth-row. The angle is deflected inward as in modern didelphids. A mental foramen is 314 University of California Publications in Geology [ Von. 13 situated beneath the anterior root of M; in the preserved portion of the lower jaw. _ Fig. 3. Peratherium merriami, n. sp. Left ramus, no. 24240, Mus. Palae. Coll, lateral view, X 2. John Day beds, Logan Butte, Oregon. The dentition present in specimen 24240 includes the two posterior premolars and the four molars of the upper jaw and comparable teeth of the lower jaw. The two posterior premolars of the upper jaw are laterally compressed, but relatively not so much as the posterior premolars of Peratherium fugax. Fach premolar possesses a single prominent cusp. In both of the teeth a small ledge is situated anterior to the principal cusp and a more extensive ledge is present behind. A furrow or concavity is plainly visible along the inner posterior side of the principal cusp in the last premolar. This furrow is not so distinct in the preceding tooth. In superior molars 1 to 3 inclusive, M+ possesses the shortest trans- verse diameter. M+ and M2? have broad crowns while the crown of M2 is relatively narrow anteroposteriorly. Fig. 4. Peratherium merriami, n. sp. Superior cheek-tooth series, no. 24240, Mus. Palae. Coll, lateral and occlusal views, X 4. John Day beds, Logan Butte, Oregon. In M+ the metacone is larger than the paracone. At least four distinct elevations or stylar cusps are situated on the outer cingulum of the tooth. The most anterior cuspule of the four is located at the antero-external angle of the tooth. A ledge extends from the cuspule along the anterior base of the paracone. The second stylar cusp is more prominent than the first and is situated near the middle of the outer base of the paracone. These two elevations or cuspules are comparable to the a and b stylar cusps noted by Bensley* for the genus 3 Bensley, B. A., The homologies of the stylar cusps in the upper molars of the Didelphyidae, Univ. Toronto Studies, Biol. Ser., no. 5, pp. 149-159, 1906. 1922] Stock-Furlong: A Marsupial from the John Day Region 315 Peratherium. Opposite the notch between paracone and metacone and on the external cingulum is situated a small elevation which is flanked behind by a larger cuspule, the latter being comparable perhaps to stylar cusp c of Bensley.* In M? the metacone is also larger than the paracone, the difference is similar to that seen in the corresponding tooth of Marmosa and is not so great as that occurring in M? of Didelphys. This tooth, in contrast to the other molar teeth, possesses the greatest number of distinet elevations on the external cingulum. Two of the elevations are situated at the antero-external angle of the tooth and are perhaps comparable to the pair situated in this region in M+. Opposite the notch between paracone and metacone may be seen two minor eleva- tions with a somewhat more pronounced stylar cusp situated immedi- ately behind. The latter is probably comparable to stylar cusp c of Bensley. The ledge which extends along the anterior base of the paracone from the most anterior stylar cusp is stronger than in M?. M2 is less robust than M2. In M2 the paracone closely approaches the metacone in size. In the Logan Butte specimen a single stylar cusp appears to be present on the external cingulum at the anterior end of the tooth from which a well defined ledge extends along the anterior base of the paracone. A rather prominent stylar cusp is situated on the external cingulum opposite the notch between paracone and metacone. A fairly prominent cuspule is developed on the cingulum at the antero-external angle of M4 and from this a ledge extends along the anterior base of the principal V-shaped eusp of the crown. Opposite the middle of the principal cusp occurs a small elevation on the cin- gulum. Examination of M‘ in three skulls of Marmosa failed to reveal the presence of an elevation in this region of the cingulum. In several skulls of Didelphys, however, two distinct cuspules are present on the external cingulum. The posterior ridge or arm of the principal V- shaped cusp in M¢ of Peratherium merriami, as in that of P. fuga, joins the cuspule or style located at the postero-external angle of the tooth. The postero-external style or cuspule is not prominent in M4 of the North American Oligocene Peratherium. In M+ of the Recent Marmosa the postero-external style is well defined. The V-shaped cusp 1s not so prominent in M4 of Marmosa as in that of P. merrianit, but the inner cusp is much better developed than in Mé of the latter form or of P. fugazx. 4 Ibid., p. 152, fig. 1. 316 University of Califorma Publications in Geology [ Von. 13 The two posterior premolars in the lower dentition are apparently less closely spaced than in Didelphys. Each of the premolars possesses a very prominent cusp behind which is situated a distinet ledge. Fig. 5. Peratherium merriami, n. sp. Inferior cheek-tooth series, no. 24240, Mus. Palae. Coll., lateral and occlusal views, X 4. John Day beds, Logan Butte, Oregon. The lower molar series is similar to that in Marmosa. In each molar the trigonid and talonid are distinct. The protoconid is a prom- inent cusp. A small cingulum is present along the antero-external border of the trigonid, comparable to that seen in molars of some species of Marmosa, and is not so well developed as in Didelphys. The cingulum is apparently but faintly indicated on molar teeth of specimen 5259, Amer. Mus. Nat. Hist. Coll., referred to Peratheriwm fugar. In M+ of P. merriami the antero-external cingulum barely reaches the protoconid. In the two following molar teeth, however, the ledge extends farther to the outer side, but does not quite reach the middle of the external surface of the protoconid. Unfortunately the trigonid in M,; has been destroyed. The talonid in this tooth is compressed transversely and consists of three distinct cusps. The hypoconulid is less prominent than either the hypoconid or the ento- eonid. MEASUREMENTS OF DENTITION Length of upper tooth row, P? to M# inclusive ...........-.-.- a10.4 mm. Length of lower tooth row, Pz to Mj inclusive ................ 12 1922] Stock-Furlong: A Marsupial from the John Day Region 317 SUMMARY A fragmentary skull of the marsupial genus Peratherium deseribed from the John Day Oligocene of Logan Butte, eastern Oregon, is regarded as the type of the new species, Peratherium merrianu. The John Day form does not greatly exceed in size the species, P. fugaz, from the Lower Oligocene White River beds of Colorado. In size, P. merriami apparently occupies a position between the Lower Oligo- cene P. fugax of North America and Lower Miocene species of Pera- therium of Europe. The material from the John Day beds furnishes additional infor- mation regarding the structure of the skull in Peratheriwm. The dentition exhibits clearly the close relationship that exists between Peratherium and the Recent Marmosa. Peratheriwm merriami is dis- tinetly less advaneed in certain dental characters than Recent poly- protodont marsupials of America. EOLOGY OF SAN BERNARDINO MOUNTAINS NORTH OF SAN GORGONIO PASS BY. 2 5 FRANCIS EDWARD VAUGHAN ——— bate ciiae Mtstis 5 Ls ra if "" "UNIVERSITY OF CALIFORNIA PRESS ee =) BERKELEY, CALIFORNIA - ae 1922 GEOLOGICAL SCIENCES.—Anprew ©. Lawson, Editor. Price, volumes 1-7, $3.50; . Note on the Faunal Zones of the Tejon Group, by Roy HE. Dickerson . Teeth of a Cestraciont Shark from the Upper Triassic of Northern California, by UNIVERSITY OF CALIFORNIA PUBLICATIONS WILLIAM WESLEY & SONS, LONDON. + ey Agent for the series in American Archaeology and Ethnology, Botany, Geological — Sciences, Physiology, and Zoology. volumes 8 and following, $5.00. Volumes 1-12 completed; volumes 13 and 14 in progress, A list of titles in volumes 1 to 7 will be sent upon request. VOLUME 8 . Is the Boulder ‘‘Batholith’’ a Laccolith? A Pranlent in Ore- ‘Geuaeet by Andrew C.,, Lawson ..-202isietcen ne eee el ee ee Harold C. Bry amt, -.2..-.cccccseacoctuspntanccereecosecessttense soeoeireuie steerer etic ee 5¢ . Bird Remains from the Pleistocene of San Pedro, California, by Loye Hoimes Miller, 10¢ . Tertiary Echinoids of the Carrizo Creek Region in the Colorado Desert, by William BS Wy, WOW inc ccncectgnenstis ftencnn bent toot bevnn eaebtenecstiteete tin iotsc cies Rt ee 20e . Fauna of the Martinez Eocene of California, by Roy Ernest Dickerson ........-.--:---0-- $1.25 . Descriptions of New Species of Fossil Mollusca from the Later Marine Neocene of California, by Bruce Martin 2.c:.sccscesticdeccc.ccenceeaecedesktesciees ee ee 20¢ . The Fernando Group near Newhall, California, by Walter A. English ..........-..--c--0-- 15¢ . Ore Deposition in and near Intrusive Rocks by Meteoric Waters, by Andrew C. TGA WS ON" “eecsaencgeuscneocntscescetteccedciuesonncnttbnetaseaoctnetst Gatcnnsa Ss ordcna tena ote 20¢ . The Agasoma-like Gastropods of the California Tertiary, by Walter A. English........ 15¢ . The Martinez and Tejon Eocene and Associated. Formations of the Santa Ana ; Mountains, by Roy H., 9. Two Vulturid Raptors from the Pleistocene of Rancho La Brea, by Loye Holmes . MM @Y o.oo. coc siesssninecsnecssssennteneossensnadeuscsstssntot becca oossopanbanae: teat test ea es Ate nae aaa 5e 10. Notes on Capromeryx Material from the Pleistocene of ‘Rancho La Brea, by Asa C.” a Chandler .nccs.nccsececdeesseesuchessonsntootees ate liccessc tees tesa en er 10 UNIVERSITY OF CALIFORNIA PUBLICATIONS BULLETIN OF THE DEPARTMENT OF GEOLOGICAL SCIENCES Vol. 13, No. 9, pp. 319-411, pls. 17-23, 1 map, 12 text-figs. December 30, 1922 GEOLOGY OF SAN BERNARDINO MOUNTAINS NORTH OF SAN GORGONIO PASS BY FRANCIS EDWARD VAUGHAN CONTENTS PAGE FTimaiteo.c Ui Li @ mn eee eran rns tee ce eee ree Raters ssitiaeiategs cencemieces eee 320 MING VOL TTD ni Meee seers see eee rere em mR Seen nes sec cuss yee re seeee eset orasungveccudte a ctnnee red ee 321 Gemerallsta tern Crt wera erecta net a escrssnete dons sueessatscaustressune she boos sets deaaniines seisueseee fon enses O21 TOW ESA Csi) Syste ty eee ree ne EP ee 323 Secon daa dat hin daciicles atreceee i ntene nites et eatyveegeeeee essa sessavieucueetten eee aseesa: 325 IRQ TTL CN CLM mere erates crite clan seeayentyns wince) weet Sere to tacs sestevea suet dveeunaten eee 333 Gla ciaNstea CUES teers eerie tet ce ioecs tie sa csayenseted.vassedtesevederes tees yisselysscusssidsinsbovsnde a ooaweiiee 335 ‘AUVONSS CG CEISTEV Hr ee a gee Re ree eee oo 337 Alluvial fans in San Gorgonio Pass.....0....0.00.cccccccccccecscsecsesevecevsevsvvsveevssvevveseveeeees 340 PS ULIANIEO ea Te Veta ee ener sone eee aa Feet eh ges ess tre tees ceca escent ieet ont soltaerecitae Ns 342 CeO lO Diya eee ace nyc c geen surce cs rea ter seriy carne hocks wre nes niles boas 344 Generallistatem ent tress mn terse yeeros at ott oe oT ee ee 344 WincitferenttiatedySChISts arccsiarerices.cceecstesesssectesss sisi ceteetssissessesdicsudesereee te esnetadns 345 ISS ULTIMO Naa SOOO greets yap re eu eee 352 eshetoldersediments tess sveh pe eee forte tat esas Hee ea chee reese 352 FATT AS ULC AC UAB ZUG Cmte eas vente eecce aren, Gyn gece pits forte seeps sleet ee 352 MUTMa COMM eStOM ears eee ese erties, Sorte ttn teeta tree cate ee 355 ATA OSSAI QUAL UZILC heres cecatess eeetvers tes vtec ccgraeseleesastessietesce-sesttizssvcnssctceseeea eats 357 Algoron the older Sedimenttss..s2s.cc.sczceosseyesetesescssiteleteasieceeessstesessts.ss0eessateeereecsieenes 361 Wonclusion se: 5sera es srtet hoa sits ate sande diets vie Sateen tee nid 363 CCAM TOG re settee sete atest yl avel MeseacTohae ay sieiesies fetes ss pibetscineeterssaees eeeaceeetese ac sieease ats 363 MuhemMentraiy:, LOTMA ON Sssaere.cesnscsecssstesetecssessvsseeesrssgusevendteeecteneeens eteeseicessensese, 374 POLAtorsAM US LOM metenacete tos -creeseviessteera ckseserasssseeeoa eee eet reece acess 374 GLONESAN AS CONC aeeceee cessive sdeseescquceseesessdets tsscdsassovscudetencieateeieinesecine sisieuseracisiie: 375 LEIBA D OF NGF IONE TOYO po pe apes cerns eee noo Heep eto sa coteeoeecasoe dee aera teen 376 SAMBA ATI AN SATICSCOMC yeseseeeesescusevesesss-tenceesetoesessceusaeocve see dhscieseesesreessteestsessesesees 378 Pipes fan QlOmierate, .............0.cececcecsseescssssessusessssessevavtereveetaescststesasstssteserscsseseceessee 379 AES ALS Gil beeeeemenerte eatin en reeset ee Ara racee raebn tn einai cue aceeuerarsntie recs boa ce. 380 Quarternary fanglomerates.........0..0cccccceccscccesessescesssecscesssevevassacsevataesatsavsecsevavseesees 384 Deep Cafion fanglomerate..........c..ccccccccccsescssesssssscessceserevecnecaessrsecsesacsecacsuracaees 384 duberolderidesert, CeWOSItS aus-.cresesastasears-siesorescotee Meecectesvessdeeseet-etecets.ccessesoeiesssees 385 @oachella tame omeratemeincrcs.:aecseanesssusteeree tess. sessucaseeeccesseeteasseeseeseeessae aes: 386 Cabezon famglomerate..............c0.+csccsceccssesseeeccessscescseessescossacsecasucsacsavresesssesassevs 387 ere hitstanelomeraten cect. skessssereccsetetetectfeeeeessestsos sete, ests assess 392 320 University of California Publications in Geology [Vou. 18 PAGE AbD avn aan pesaecaseet cxenek Sea ects eec de seta a 393 ROE 9(0 C6] F101: MP en PE er RF rE ae a Seve nexspdodddooccac 393 Folds modified by intrusions and faults........0..0..0.cccccccscccesccscecsessessee ses cetenee 393 Quatermary Daults, 25 oi. cosd.crcescscancesstacesuendesee] T.1 NN. T3s. a 50! \) 1.48. 2 1 o a 2 53 = ° a 2 a fe Contour interval 100 feet. Datum is mean sea level. A.HOEN CO. BAL TO, MD: G30" QUATERNARY PLIOCENE Mr0cENnE? PALEOZOIC PLIOCENE JURASSIC SEDIMENTARY ROCKS Alluvium Glacial till Heights fanglomerate Cabezon fanglomerate Coachella fanglomerate Old Desert deposits Deep fanglomerate Santa Ana sandstone Hathaway sandstone and shale Potato sandstone Saragossa quartzite Silurian or Devonian oon Furnace limestone Upper Cambrian and Ordovician Arrastre quartzite Lower Cambrian Undifferentiated schists IGNEOUS ROCKS Cactus granite Heterogeneous plutonic rocks: SYMBOLS FAULTS Exposed —$<—$——— Probables” =. SS) Se Buried CoNTACT « SS ae Approximate [205111101 Dip AND STRIKE Uke) xe wy + E> age a “June 30,1822. = 7S z 7 es NEW SPECIES FROM THE CRETACEOUS OF THE SANTA ANA MOUNTAINS, CALIFORNIA BY E. L. PACKARD / UNIVERSITY;@F CALIFORNIA PRESS BERKELEY, CALIFORNIA UNIVERSITY OF ete hts PUBLICATIONS it WILLIAM WESLEY & SONS, LONDON “Agent for the series in American Archaeology and Ethnology, Botany, Geological Sciences, Physiology, and Zoology. : GEOLOGICAL SCIENCES.—Anprew ©. Lawson, Editor. Price, yolumes 17, $3.50; volumes 8 and following, $5.00. Volumes 1-12 completed; volume 13 in progress. A List of titles in volumes 1 to 7 will be sent upon request. 8 ~ VOLUME 8 1. Is the Boulder ‘‘Batholith’’ a Laccolith? A Problem in Ore-Genesis, by Andrew GP A WSO Toe. ceca lenensandntetoecehddvesceonttpibea lea set ati dekten cates SUES a Die: nk -25¢ 2. Note on the Faunal Zones of the Tejon Group, by Roy E. Dickerson ............c.-::sce-o-= 10¢ 3. Teeth of a Cestraciont Shark from the Upper Triassic of Northern California, by el Hatold s@. Bryant: 2u.ceses costes encceoecte-costier ode divceteache tigen et a ee By gel 4, Bird Remains from the Pleistocene of San Pedro, California, by Loye Holmes Miller. 10¢ ~ 5. Tertiary Echinoids of the Carrizo Creek Region in the Colorado Desert, by William é Se, en MM MM Sy 200 6. Fauna of the Martinez Eocene of California, by Roy Ernest Dickerson ..........---0-0--- $1.25 «© 7. Descriptions of New Species of Fossil Mollusea from the Later Marine Neocene of ian California, by Bruce Martin ........-....--sscssscssesccesssesscsesssoessseessennensnnercneternenecnecsnnessieteaeeae 200s: ae 8. The Fernando Group near Newhall, California, by Walter A. English ..........--c:se0----- 15¢— 9. Ore Deposition in and near Intrusive Rocks by Meteoric Waters, by Andrew C, TRS OM Be. on na nana ceabecntenseceecopese ony tnpqezontincr scigadess Gece: thaedecdeinctnn gs eae ne rr 20¢ 10. The Agasoma-like Gastropods of the California Tertiary, by Walter A. English.....615¢ 11. The Martinez and Tejon Eocene and Associated Formations of the Santa Ana a Mountains, by Roy “Hl Dickerson .....csc2.cpice-cttc-coensetscnnen-acceencetslleotgartsshalsases oe See 20c— 12. The Occurrence of Tertiary Mammalian Remains in Northeastern Nevada, by John Fe e. Carer TAA My ..2. 2 enc8 02-302 Se Rico cccacdeeazeasonctccnenoLetenennascadunecbadhcesietoga sts Coote ane 10e° 13. Remains of Land Mammals from Marine Tertiary Beds in the Tejon Hills, Cali- ‘fe formia, by John CO. (Merriam! 2 eo 22-.2. ccs. otetcecpseseapencceesten bt ittan cee ae de ib 14. The Martinez Eocene and Associated Formations at Rock Creek on the Western ~ 7 . [444 UNIV. CALIF, PUBL. BULL, DEPT. GEOL. SCi. [PACKARD] VOL. 13, PL. 29 Fig. Fig. Fig. Fig. Fig. 5 4a. 4b. EXPLANATION OF PLATE 30 Astarte ovoides, n. sp. X 1%. Type no. 12280, loc. 2157. Cardium coronaensis, n. sp. X 1. Left valve of type no. 12281, loc. 2130. Spondylus rugosus, n. sp. X 1. Left valve of type no. 12277, loc. 2143. Astarte lapidis, n. sp. X-1%. Exterior of type no. 12285, loc. 2135. Astarte lapidis, n. sp. X 1%. Hinge of type no. 12285. [446] UNIV. “CALIF. PUBL; BULL, DEPT. GEOL. SCI. [PACKARD] VOL. 18, PL. GO da 4b Fa EXPLANATION OF PLATE 31 Gastrochaena, sp. No. 12282, loc. 2179. Meretrix nitida (Gabb) var. major, n. var. X 1. Left valve of type no. 12279, loc. 2169. ; Spondylus rugosus, n. sp. X 1. Right valve of type no. 12277, loc. 2143. Cardium (Protocardia), sp. X 14%. No. 12283, loc. 2177. Anatina (?), sp. X 1%. No. 12286, loc. 2162. [448] PL. 31 13, CALIF. PUBL. BULL, DEPT. GEOL. SCI. [PACKARD] VOL, UNIV. EXPLANATION OF PLATE 32 Fig. la. Homomya hardingensis, n. sp. Anterior aspect. Fig. 1b. Homomya hardingensis, n. sp. Right valve. Figs. la, 1b, type no. 12291, loc. 2134. Natural size. UNIV. "CALE “PUBL BULLE, DEPT, GEOL, SChi* [| RACKARD]) VOL. 1G, Pk, 382 1b EXPLANATION OF PLATE 33 Tellina, sp. X 1%. No. 12308, loc. 2168. Meretrix (?), sp. X 1. No. 12306, loc. 2167. Tellina alisoensis, n. sp. X 1. Type no. 12309, loc. 2168. Tellina santana, n. sp. X 1. Type no. 12310, loc. 2169. Meretrix angulata, n. sp. X 1. Type no. 12307, loc. 2136. Astarte (?) suleata. xX 1%. Type no. 12305, loc. 2141. [452] UNIVE CALIP RUBE BULL DEPT GEOL, SCl, "PACKARD ] VOL, We, PE. 3s EXPLANATION OF PLATE 34 Fig. 1. Panope californica, n. sp. Right valve of type no. 12292, loe. 2142. Fig. 2. Siliqua alisoensis, n. sp. Type no. 12293, loc. 2169. All figures natural size. [454 | UNIViCALIR (RUBE, BULL, DEPT: GEOL, SCI, [PPACKARD] VOL, 138, PL 64 Fig. Fig. Fig. Fig. Fig. Fig. Fig. EXPLANATION OF PLATE 35 . Amauropsis pseudoalveata, n. sp. X 1%. . Amauropsis pseudoalveata, n. sp. X& 1%. Figs. la, 1b, type no. 12301, loe. 2151. . Gyrodes californica, n. sp. X 1%. . Gyrodes californica, n. sp. X 1%. Figs. 2a, 2b, type no. 12300, loc. 2167. Amauropsis pseudoalveata, n. sp. X 1. Cotype no. 12302, loc. 2157. Cerithium (?) suciaensis, n. sp. X 1. Type no. 12303, loc. 2209. Siphonala dubius, n. sp. X 1. Type no. 12304, from Chico of Santa Ana Mountains, California. [456] UNIV. CALIF, PU BET BUEE DEPT, G EOER SG [ PAGKARD ] VOL, eo an i = ft : i im i i > ’ i ‘ e — . A * sh : ¢ 7 i | | = ot : 4, er - Fig. Fig. Fig. Fig. Fig. Fig. EXPLANATION OF PLATE 36 Aporrhais vetus, n. sp. X 1. Type no. 12298, loc. 2171. Odostomia santana, n. sp. X 4%. Type no. 12299, loc. 2169. Volutoderma santana, n. sp. X 1. Type no. 12294, loc. 2135. . Actaeonella oviformis Gabb. XX 1. Specimen no. 12295, loc. 2138. 5a. Alaria nodosa, n. sp. X 1. Cotype no. 12296, loc. 2142. 5b. Alaria nodosa, n. sp. X 1. Type no. 12297, loc. 2155. gee ade Pee [458] UNIV (CALIF, PUBE, BULL, DEPT, GEOL, SCI, [PACKARD] VOL. 13, PL: SG Bye) ie a EXPLANATION OF PLATE 37 Volutoderma magna, n. sp. X 1. Type no. 12274, loc. 2166. ok Lysis californiensis, n. sp. X 1. Type no. 12287, loe. 2167. ge Lysis californiensis, n. sp. X 1. Cotype no. 12288, loc. 2134. Bullaria tumida, n. sp. X 1. Type no. 12289, loc. 2157. [460] WNINe CALIF, PUBL, BULLE, DEPT. GEOL. SCI. [PACKARD] VOL. 13, PL. S7 of % coe 5 * . 5 4 ‘ ‘ 1 1 oe 7. EXPLANATION OF PLATE 38 Ls a Volutoderma magna, n. sp. (?). Natural size. No. 12278, loc. 2166. UNIV, CALIF. PUBL. BULL. DEPT. GEOi. SCI. [PACKARD] VOL. 13, PL. 38 —_ a f T - > a - : - S * ws ’ = ‘ 7 ¥ ? . + . ‘ re . . + ' ‘ * bs , ‘ a _ 7 = x . i + ‘ - . ‘ 1 ‘ y 4 7 = a - a . anon lai Ih INDEX* Abich, H., cited, 74. Acanthina perrini, description of, 157; figures of, opp. 174. Actinolite, 217. Adams, A. L., cited, 72. Abel, C., quoted, 69; cited, 71. Alachtherium, 101. Alaria nodosa, description of, 430; figures of, opp. 458. Allen, J. A., cited, 59, 60, 75, 76, 83, 87. Allodesmus, 26, 106; type specimen of, occurrence of in Temblor beds of Kern River region, 26; re- ferred specimens of, 26; char- acters of, 26. kernensis, 26 ff.; compared with Prorosmarus alleni, Mirounga an- gustirostris, Eumetopias, Proros- marus, Alachtherium, Pontolis magnus, Eumetopias jubata, Des- matophoca oregonensis, Desma- tophoca, Zalophus Allodesmus, Eumetopias stelleri, Callotaria, Pantolestes, Phoea richardii, 26- 44, passim; skull of, 29 ff.; teeth of, 32 ff.; limit elements of, 35 ff.; figures of, 27, 30, 32, 33, 34, 35, 38, 40, 41, 43. Alluvial fans, west of Cushenberry Springs, California, 340; in San Gorgonio Pass, 340 ff., 393. Amauropsis pseudoalveata, descrip- tion of, 429; compared with A. alveata and Euspira tabulata, 429; figures of, opp. 456. Ameghino, F., cited, 52, 59, 61. Amphibolite schist of Cuyamaca re- gion, 183. Anatina (?), sp., description of, 423; figure of, opp. 448. Anderson, F. M., cited, 151, 154, 156. Anderson and Martin, cited, 147. Andrews, C. W., cited, 76, 86. Andrian, F. F., and Paul, K. M., cited, 73. Antelope Creek, California, limestone of, 355. Antigona willisi, description of, 152; figures of, opp. 168. Aplite, 210. Aporrhais vetus, description of, 431; figure of, opp. 458. Arctocephalus, 108. Arnold, R., cited, 135, 149, note 20. Arrastre Creek, California, 333, 351, 357. Arrastre quartzite, 344, 351, 352 ff. Ascending solutions, 280 ff. Astarte lapidis, description of, 423; figures of, opp. 446. ovoides, description of, 424; figure of, opp. 440. sulcata, description of, 424; figure of, opp. 452. Astrodapsis brewerianus, occurring above contact on southwest side of Mt. Diablo, 137. Augite of Friday Mine, 216. Baker, C. L., quoted, 324. Baldwin Lake, California, 321; granite of, 365. Banning, alluvial fan at, 341. Banning Heights, California, 327, 343; Heights fanglomerate, 344, 392. Barlow, A. E., cited, 230, 232. Barrett-Hamilton, G. E. H., cited, 85. Basalt of Mohave Desert, 337; of San Bernardino Mountains, 380 ff. Basalt flow of Antelope Creek, 324. Basalt surface, pre-, of Mohave Des- ert, 337. Basie dikes of Cuyamaca region, 209; of Friday Mine, 214. Bateman, A. M., cited, 237. Bathyuriseus, occurring in Middle Cambrian of Bristol Mountain, 4. howelli, specimens similar to found in Middle Cambrian of Bristol Mountain, 6. Bear Valley, San Bernardino Moun- tains, California, 321, 326, 327, 330. Becker, G. F., quoted, 289. Bell, Robert, cited, 229, 230. Berry, E. W., and Gregory, W. K., cited, 26, 47, 54. Beyschlag-Krusch-Vogt, cited, 233. Blackhawk Cafion, alluvial fans at, 340. Blainville, H. M. D., cited, 47, 69, 70. Blaisdell Cation, alluvial fan at, 341. Boué, A., cited, 69. Bowers, S8., cited, 61. Branner, J. C., Arnold, R., and New- some, J. J., cited, 135. Briones Formation of Middle Cali- fornia, The, 133-174. Briones formation, areal distribution of, 135 f.; description of, 136 ff.; fauna of, 139 ff. Bristol Mountain, California, 1; de- scription of, 2; geological rela- tions, 3. Bristol Mountain Section, 5. * Univ. Calif. Publ. Bull. Dept. Geol. Sci., vol. 13. [415] st Ye, ~ & 7 W,.. ; tional Musev® atl Index Brown, R., cited, 55, 83. Brown, T., cited, 80. Brown hornblende of Friday Mine, 216. Brown-hornblende norite of Cuya- maca region, description of, 197. Browne, D. H., cited, 233. Bruhl, C. B., cited, 73. Bullaria tumida, description of, 433; figure of, opp. 460. Cabezon, alluvium at, 341. Cabezon fanglomerate, 344, 387. Cactus granite, 344, 365. Cadiz, California, 1. Calcite of Friday Mine, 217. Calkins, F. C., cited, 191, 215. Callavia = C.? nevadensis, 6. Calliostoma obliquistriata, description of, 153; compared with C. bicari- natum, 153; figures of, opp. 173. Callophoca, 123. Calvert, F., and Newmayr, M., cited, 74, Cambrian, Lower, of Bristol Moun- Taine. 3.50 @ LauMa Ol 0: Middle, of Bristol Mountain, 4, 5; fauna of, 6. Cambrian area in Canada, pre-, physiographic axis of, 271. Cambrian granite, pre-, of Bristol Mountain, underlying sediment- ary formations, 3; erosional sur- face of, 7. Campbell and Knight, cited, 236. Carboniferous of Bristol Mountain, 4,5; fauna of, 6. Cardium (Protocardia), sp., descrip- tion of, 425; compared with C. sagittatus, 425; figure of, opp. 448. corbis, description of, 150; figure of, opp. 168. coronaensis, description of, 424; figure of, opp. 440. Carneros Creek, California, 135. Castle, W. E., cited, 57. Cavins, A. C., cited, 3. Cerithium (?), sp., description of, 430; compared with C. (?) su- ciaensis, 430. suciaensis, description of, 430; fig- ure of, opp. 456. Chlorite of Friday Mine, 216. Chalecopyrite of Friday Mine, 215. Cienaga Seca Creek, rocks of, 344. Cierbo formation, Briones distinct from, 134. Cirques of San Bernardino Mountains, 335. Clark, B. L., cited, 134, 138, 146, 149, 158, 154, 155, 299. Clark, Clifton, W., 1; cited, 362. Cliothyridina, 6. [416] Clipper Mountains, California, ab- sence of fossils in, 2. Coachella fanglomerate, 344, 386. Cobalt, Ontario, relation of veins to folds at, plan of, 258; structures at, 262; easterly-westerly faults at, 265, 277; paragenesis of ores at, 270; genesis of ores at, 271; minor structures at, 276 ff. Cobalt District, Ontario, Canada, Genesis of the Ores of, 253-310. Cobalt district, formations of, 254; structures of, 255; faults at, 262; bibliography of, 306. Cobalt Lake fault, 256, 279; syncline, 279. Cobalt Series, 255, 257. Cobalt silver veins, 256, 267. Cobalt surface, pre-, 257; origin of, 258. Coleman, A. P., cited, 194, 232, 239. Collins, J. H., cited, 255. Condon, Thomas, quoted, 31; cited, 62, 63. Conrad, cited, 153. Cooper, W., cited, 14. Cope, E. D., cited, 51, 76. Cottonwood Mountains, 320. Cretaceous of the Santa Ana Moun- California, tains, California, New Species from, 413-462. Cretaceous, Upper, ancestral Pho- cidae of, in New Jersey, 68. Crustified veins, 287. Crystallization, order of, in Cuya- maca rocks, 203. Cucullaea (?) sp., 417. cordiformis, description of, 417; figure of, opp. 434. lirata, description of, 417; compared with Trigonarea telugensis, 417; figures of, opp. 434, 436. ponderosa Whiteaves, description of, 416; compared with C. truncata, 416. Cul de sac fractures, 304. Cuvier, G., cited, 46. Cuyamaca basic igneous mass, age of, 207. Cuyamaca basic intrusive, 193 ff. Cuyamaca Mountains, 178, 179. Cuyamaca Region of California, Ge- ology of, 175-252. Cuyamaca region, relief of, 179; climate and vegetation of, 180; physiography of, 180; geology of, 181 ff.; geological map of, opp. 182; crystallization in rocks, 203; basie dykes, 209; aplite of, 210; geologic structure of, 211. Cycles of erosion, San Bernardino Mountains, 323, 325, 333. Index Cyrena (Corbicula) diabloensis, de- scription of, 150; compared with C. californica, 150; figures of, opp. 164. Cystophorinae, 90. Dall, cited, 147, 148. Daly, R. A., cited, 207, 274, 286, 297. Darton, N. H., cited, 1, 4, 361; quoted, 373. Deep Cafion fanglomerate, 344, 384. Defrance, G. A., cited, 50. De Alessandri, G., cited, 72. De Kay, J. E., cited, 50. Delfortrie, E., cited, 59. Descending solutions, 279. Desert north of San Bernardino Mountains, 337; erosional pro- cesses in, 338; springs in, 340; deposits, older, 385. Desert topography, example of, 338. Desmatophoea, 107. Diabase at Cobalt, described, 261; in- jection of, 273 ff. Diabase sill, relation of, to Keewatin and Cobalt series, figure of, 259; at Cobalt, 260. Diablo, Mt., California, exposures of Briones formation on, 136. Dickerson, R. E., cited, 714. Dickson, C. W., cited, 235, Dresser, M. A., cited, 233. Du Bus, Vicomte N., cited, 47. Duvernoy, G. L., cited, 47. Hichwald, E., cited, 48, 73, 74. Ellis, A. S., cited, 207. Elliott, H. W., cited, 55. Elsie Caves, California, granite of, 367. Emmons, S. F., cited, 263; note, 15. English, W. A., cited, 158. Eocene (Lower Mokattam?), Middle, ancestral Phocidae of, in Egypt, 69. Epitonium, sp., description of, 428. Erignathus, 116. Erwin Lake, California, 321. Eumetopias, 106. Exogyra californica, description of, 421; compared with E. costata, 421; figure of, opp. 440. inornata, description of, 420; figure of, opp. 440. Fairbanks, H. W., cited, 188. Fairbanks, H. W., and Carey, E. P., cited, 335; quoted, 336. Fanglomerate: in Santa Ana Canon, 388 ff.; of Tertiary and Quater- nary age, south flank of San Ber- nardino Mountains, 344; of Ban- ning Heights, 344, 392. Fault scarp of Mission Creek, 401. Fauna, from Bristol Mountain, 6. from Briones formation, 139 ff.; complete list of known species from, with their geologic range, 141 ff.; relation to Monterey fauna, 144; relation to San Pablo fauna, 144 ff. from Lion sandstone, 376. Fick, cited, 289. Fick’s law, 289, 291, 305. Finlay, A., cited, 305, note, 25. Fischer, de Waldheim, cited, 158; note, 36. Fish, P. A., cited, 96. Flores, E., cited, 72. Flower, W. H., cited, 93. Folds, at Cobalt, 262; in San Ber- nardino Mountains, modified by intrusions and faults, 393. Forsyth-Major, C. J., cited, 77, 78. Fossil pinnipeds, see Pinnipeds, fossil. Fossil soil at Cobalt, 258. Foullon, H. B., cited, 230. Friday Mine, California, 179, 212. Friday Mine Ore Body, 212 ff.; ver- tical section through, figured, 214, Fry Mountain, California, 337, 373. Fuchs, T., cited, 73. Fulton, C. H., cited, 240. Fulton, C. H., and Goodner, I. E., cited, 241. Furlong, E. L., 311. Furnace limestone, 344, 555 ff. Gabb, cited, 150, 156, 158. Gabbro of Cuyamaca region, descrip- tion of, 196. Gastrochaena, sp., description of, 428; compared with G. aspergil- loides, 428; figure of, opp. 448. Gaudry, A., cited, 79. Genesis of the Ores of the Cobalt Dis- trict, Ontario, Canada, 253-310. Geology of the Cuyamaca Region of California, 175-252. Geology of San Bernardino Moun- tains North of San Gorgonio Pass, 319-411. Georgi, J. G., cited, 46. Gervais, P., cited, 59, 60, 76, 78. Gervais, P., and Serres, M., cited, 75. Glacial cirques, San Gorgonio Moun- tain, 323, 335. Gold, of Holeomb Valley, 409. Gold Mountain, California, 325, 394. Goodner, I. E., and Fulton, C. H., cited, 241. Gradational contact at Friday Mine, 226. Granite gneiss of San Bernardino Mountains, 370. Granite Peak, California, granite of, 366. Granites of San Bernardino Moun- tains, 363 ff. Grapevine Cafion, limestone of, 356. Gratiolet, B., cited, 50. Index Gravitative settling, as applied to Friday Mine deposit, 238. Green hornblende of Friday Mine, 216. Greenlead Camp, California, ore of, 410. Gregory, W. K., cited, 85, 96. Gregory, W. K., and Berry, E. W., cited, 26, 47, 54. Gryphoca, 115. Guiseardi, G., cited, 72. Gypsum, beds of, near Bristol Moun- tain, 2. Gyrodes californica, description of, “ 429; compared with G. Canaden- sis and G. compressus, 429; fig- ures of, opp. 456. Haast, J., cited, 61. Haig, H. A., cited, 96. Hallgrimsson, J., cited, 83. Harker, A., cited, 208, 233. Harker, A., and Marr, J. E., cited, 186. Harmer, F. W., cited, 77. Hasse, J., cited, 48, 71. Hathaway Canon, 328. Hathaway Creek, California, glacia- tion at, 336. Hathaway formation, 376 ff.; sand- stone and shale, 344. Hay, O. P., cited, 51, 59. Heights fanglomerate, 344, 392. Hepburn, D., cited, 89. Hercules shale member, 137. Hershey, O. H., cited, 7, 361. Highland Range, Nevada, 2. Hipparion Tooth from the Siestan Deposits of the Berkeley Hills, California, Note on, 19-21. Hipparion near mohavense, deserip- tion of, 19; compared with H. platystyle and H. mohavense, 19-21; figure of, 20. Holcomb Valley, California, 321, 326; fanglomerate of, 388. Homomya hardingensis, description of, 423; figures of, opp. 450. Hore, R. E., cited, 232. Howe, E., cited, 237. Hudson, F. S., 175. Huxley, T., cited, 93. Hydrurga, 114. Hypersthene diorite of Cuyamaca re- gion, description of, 198. Iddings, J. P., cited, 202. Igneous rocks, silver in, 299. Injection gneiss of Cuyamaca region, 184 ff. Tron Mountains, California. See Bristol Mountain. Trregular contact, on southwest side of Mt. Diablo, 137. Jackson, C. T., cited, 78. Jager, G. F., cited, 47. Jentzsch, A., and Tenne, C. A., cited, 79. Johansen, F., cited, 55. John Day Oligocene deposits, oceur- rence of, 312; marsupial remains in, 312. Julian, California, 178. Julian schists, age of, 188 ff. Julian schist series, 182 ff. Keewatin formations of Cobalt, 254, 257. Keewatin roof blocks, 260. Kemp, J. F., cited, 284, 293. Kellogg, Remington, 23. Kerr Lake, Ontario, 260. Kew, W. S. W., cited, 375. Kinberg, J. G. H., cited, 79. Kitching Peak, California, 324. Knight, and Miller, cited, 298, 302. Knopf, A., cited, 233, 234. Knox, R., cited, 79. Koilopleura, description of, 157; com- pared with Agasoma and Acan- thina, 158; figures of, opp. 174. sinuata, 158; shell described, 158; note, 37; figures of, opp. 174. Krusch-Beyschlag-Vogt, cited, 233. Kikenthal, W., cited, 97. Laguna Mountain, California, 178. La Jolla, California, 45. Lake Timiskaming, Ontario, 272. Lankester, R., cited, 48, 49, 55. Larsen, E. S., cited, 207. Laurentian granite of Cobalt, 254. Lawley, R., cited, 77. Lawson, A. C., cited, 134, 137, 286, 287, 293, 338, 358; quoted, 282 283. Leda furlongi, description of, 147; compared with L. taphria Dall, 147, with L. ochsneri Anderson and Martin, 147; with L. whit- mani Dall, 148; figures of, opp. 160. Leibnitz, God. W. von, cited, 46. Leidy, J., cited, 12, 51, 68, 78. Leith, C. K., cited, 264, 278. Leptophoca, 123. Leriche, M., cited, 58. Leseur, C. A., and Peron, F., cited, 61. Liesegang, R. E., cited, 289, 293, note 17. Lima subnodosa, description, 421; figure of, opp. 442. Limestone in San Gabriel Moun- tains, 362. Limopsis silveradoensis, description of, 419; figures of, opp. 440. Lindgren, W., quoted, 283, 284; cited, 287, 293, 350, 363, note 16, 374. Lion sandstone, 344, 375; age of, 378. Lion Cafion, section west of, figure of, 378. , Index Lloyd, L., cited, 82. Lobodon, 115. Lobodoninae, 89. Logan Butte, Eastern Oregon, A Marsupial from the John Day Oligocene of, 311-317. Logan, W. E., cited, 79. Logan Butte, Oregon, John Day Oli- gocene deposits at, 312; known Oligocene carnivors from, 312. Lorrain granite of Cobalt, 255, Lonnberg, E., cited, 80. Lower and Middle Cambrian Forma- tions of the Mohave Desert, 1. Lydekker, R., cited, 83. Lyell, Sir Charles, cited, 50, 71. Lysis californiensis, description, 431; compared with L. suciensis, 432; figure of, opp. 460. Magmatic heat, mechanical effects of, 274, Magnetite of Friday Mine, 215. Major structural axes at Cobalt, 271. Marble Mountains, California, ab- sence of fossils in, 2. Marginal chilling, effect of on Cuya- maca norites and gabbros, 199. Marr, J. E., and Harker, A., cited, 186. A Marsupial from the John Day Oli- gocene of Logan Butte, Eastern Oregon, 311-317. Martin, and Anderson, cited, 147. Matthew, W. D., cited, 57, 65, 66, 94, 99. McCoy, F., cited, 60. Means Wells, California, 339. Mendenhall, W. C., quoted, 189, 322. Meretrix ?, sp., description of, 426; figure of, opp. 452. angulata, description of, 425; fig- ure of, opp. 252. nitida var. major, description of, 425; figure of, opp. 252. Merriam, John C., 9; cited, 134, 146, 312. Merrill, F. J. H., quoted, 189, 207. “Mesonacis gilberti, 6. Mesotaria, 109 f. Michelina, 6. Micromitra (Paternia) prospectensis, 6. Millard Cafion, 328; alluvial fan at, 341; catchment area at, 341. Miller, L. H., cited, 80. Miller, G. S., cited, 91. Miller, W. G., cited, 255; quoted, 255, 256. Miller and Knight, cited, 298, 302. Minerals of massive ore of Friday Mine, 215ff., interrelations of, 217; of veins of Cobalt, 256. Mineralized joints, types of, 266. [419] Miocene and Pleistocene Deposits of California, Pinnipeds from, 23- 132. Miocene (Sarmatian), ancestral Pho- cidae of, in Europe and Malta, 73 f.; (Burdigalian), Lower, an- cestral Phocidae in diatomaceous shales of, at Lompoc, California, 70; (Lortonian), Upper, ances- tral Phocidae of, in America, Europe, Malta, and Russia, 70 ff.; (Pontian), ancestral Phocidae of, in Russia and America, 74; (Helvetian), Middle, ancestral Phocidae of, in Europe, 70. Miocene surface, post-, of Barstow, 324, Mission Creek fault, 329, 330, 342, 403; figure of, northeast of Hog Ranch, 402. Mitchell, P. C., cited, 96. Mitchill, S. L., Smith, J. Cooper, W., cited, 50. Mivart, G., cited, 85, 93. Modiolus gabbi subconvexus, descrip- tion of, 149; figure of, opp. 164. veronensis, description of, 150; fig- ure of, opp. 164. Mohave Desert, California, 1. Mohave Desert, Lower and Middle Cambrian Formations of, 1-7. Monachinae, 87 ff. Monarch Flat, California, ore of, 410. Monotherium, 112 ff. Monterey formation, composition of upper part of, 137. Monterey group, Briones not to be classified with, 134. Montreal River, Ontario, 272. Monti, J., cited, 46. Moraines, of San Bernardino Moun- tains, 335. Morongo Valley, California, 321, 329. Mourlon, M., cited, 75. Munster, G. G., cited, 69. Murie, J., cited, 57. Nassa whitneyi, occurring below con- tact on southwest side of Mt. Diablo, 138; description of, 154; compared with N. pabloensis and N. arnoldi, 154; figures of, opp. 172. Negro Butte, 398. Nehring, A., cited, 83. Neumayr, M., and Calvert, F., cited, 74 A., and California, 337, 383, New Species from the Cretaceous of the Santa Ana Mountains, Cali- fornia, 413-462. Newsome, J. J., Branner, J. C., and Arnold, R., cited, 135. Newton, E. T., cited, 76, 80. Index Nickeliferous pyrrhotite, theories of origin, 228, Nipissing diabase, 255; analyses of by Miller and Knight, 298. Noble, L. F., quoted, 362. Nordmann, A., cited, 73, 74. Norite of Cuyamaca region, descrip- tion, 195. Note on an Hipparion Tooth from the Siestan Deposits of the Berkeley Hills, California, 19-21. Notes on Peccary Remains from Rancho La Brea, 9-17. Odobenidae, 101; ancestral, 46 ff. Odobenotherium, 104. Odostomia santana, description, 428; compared with O.? inornata, 428; figure of, opp. 458. Old Woman Springs, California, sand dune country east of, 340. Olenellus fremonti, 6. Oligocene, the John Day, of Logan Butte, Eastern Oregon, A Mar- supial from, 311-317. Oligocene (Rupelian), Middle, ances- tral Phocidae of, in Holland, 69. Oliva simondsi, description of, 159; compared with O. peruviana con- formis, 159; figures of, opp. 174. Olivine gabbro of Cuyamaca region, description, 195. Olivine norite of Cuyamaca region, description of, 195. Ore body at Friday Mine, relation to enclosing rocks, 225; origin, 227. Ores of the Cobalt District, Ontario, Canada, Genesis of, 253-310. Orindan deposits of Berkeley Hills, scarcity of mammalian remains amyl: Osborn, H. F., quoted, 68; cited, 78. Osburn, R. C., cited, 97. Osmosis, 290. Ostrea crescentica, description, 420; compared with O. skidgatensis, 420; figures of, opp. 438. taxidonta, description, 426; com- pared with O. lurida and O, acu- tirostris, 420. Ostrea titan, 45. Ostwald, Wm., cited, 301. Ostwald, Wolfgang, cited, 289; bays Otariidae, 26, 106; ancestral, 58 ff. incertae sedis, 108. Packard, E. L., 413; cited, 414. Page, D., cited, 79. Pagophoca, 123. Paleophoea, 111. Paleotaria, 109. Panope californica, description, 427; figure of, opp. 454. Paragneiss and coarse schist of Cuya- maca region, 183. note, [420] Paul, K. M., and Andrian, F. F., cited, 73. Pease, Young, and Strand, cited, 241. Peccary Remains from Rancho La Brea, Notes on, 9-17. Pecten (?), sp.; description of, 421; figure of, opp. 440. (Pecten) andersoni gonicostis, de- scription of, 149; compared with P. andersoni, 149; figure of, opp. 160. crassicardo, 45. raymondi brionianus, description of, 148 f.; compared with P. raymondi, 149. raymondi, figures of, opp. 160. (Lyropecten) ricei, description of, 148; figures of, opp. 162. Tolmani Hall and Ambrose, figures of, opp. 164. (Lyropecten) vickeryi, description, 148; figure of, opp. 166. Pegmatite, of Cuyamaca region, 209; of Friday Mine, 214; of Rock Corral, 371. Pegmatite dikes, 350. Peratherium merriami, 312; type specimen of, 312; specific char- acters of, 312; compared with P. fugax, Marmosa, and Didelphys, 312-316, passim; description, 313 ff.; figures of, 313, 314, 316. Peridotite of Cuyamaca region, de- scription, 197. Peron, F., and Leseur, C. A., cited, 61. Peters, K. F., cited, 74. Peters, W., cited, 91. Peterson Lake, Ontario, 260. Phoea, 117 ff. sp. A., 45; compared with allodes- mus, 45. sp. B., 45. Phoeanella, 121. Phocid, indet., 44; compared with Phoca richardii, 44; with allo- desmus, 45. Phocidae, 44, 109; ancestral, 66 ff. Phocinae, 81 ff. Pictet, F. J., cited, 47. Pinnipedia, 101; table showing varia- tions in dental formulae of sub- order, 84; paleontologic evidence bearing on origin of, 92 ff.; fossil remains incorrectly referred to, 124 ff. Pinnipedia, fossil, known, chart show- ing geographic and_ geologic range of, following 46; a check list of, 101 ff. Pinnipeds from Miocene and Plei- stocene Deposits of California, 23-132. Pipes, The, California, 321. Index Pipes fanglomerate, 344, 379; age of, 380. Platygonus, possibly n. sp. or n. subsp., 10ff.; compared with Mylohyus, Tayassu, P. leptor- hinus, P. compressus, P. alemani, P. vetus, 10-15, passim; figures of, 11, 13, 16; skull of, 10; denti- tion of, 13; limb elements of, 15. Platyphoca, 117. Playas, 340. Pleistocene, ancestral Phocidae of, in America and Europe, 78 ff. Pliocene (Scaldisian), Middle, an- cestral Phocidae of, in Antwerp basin, 75; (Astian), Upper, an- cestral Phocidae of, in Europe and Egypt, 75 ff. Pocock, R. I., cited, 98. Polydymite of Friday Mine, 216. Pontolis, 106. Posepny, F., cited, 235, 282, 293. Postearboniferous granites in Mohave Desert, 7. Potato sandstone, 344, 374, 395. Potrero Cafion, catchment area at, 341, Pre-Cambrian granite Mountain, 3, 7. Pristiphoca, 110. Prophoea, 116. Prorosmarus, 101. Providence Range, California, 2. Pyrrhotite, of Friday Mine, 215; syn- genetic origin of, 229 ff.; as ap- plied to Friday Mine deposit, 238; epigenetic origin of, 235 ff.; theories involving replacement, as applied to Friday Mine de- posit, 239 ff.; intrusive sulphide theory of origin of, 237. Quaternary faults of San Bernardino Mountains, 396. Quaternary fanglomerates of Bernardino Mountains, 384. Quartz diorite of Cuyamaca region, acewOe: Quartz gabbro of Cuyamaca region, description, 199. Quartz-mica-schist of Cuyamaca re- gion, 182. Quartz norite of Cuyamaca region, description, 199. Quartzite of Cuyamaca region, 183. Rabbit Springs, California, green vegetation near, 340. Racovitza, E. G., cited, 83. Rancho La Brea, California, 9. Ransome, F. L., cited, 362, note 14, 363, note 17. Rattlesnake Cafion, alluvial fan at, 340. Rattlesnake Creek, granite of, 371. in Bristol San [421] Rattlesnake Pliocene deposits, resem- blance of beds at Logan Butte to, 312. Raywood Flat, California, 330, 389; composition of ridge north of, 349. Rhoads, S. N., cited, 51. Rickard, T. A., cited, 282. Robert, E., cited, 80. Rock alteration in Cuyamaca region, 204, Rock types in Cuyamaca region, re- lation between, 205. Rock Corral, California, alluvial fan at, 340. Rocks of Friday Mine, 213. Rogers, A. F., and Tolman, C. F., Jr., cited, 228; quoted, 236, 237. Roscoe and Schorlemmer, quoted, 296. Rose Mine, California, limestone of, 355; ore of, 410. Rosenbusch, H., cited, 186. Royal Ontario Nickel Commission, cited, 228. Rutton, L., cited, 48, 49, 50, 54. Salt, beds of near Bristol Mountain, 2. San Andreas fault, 342, 399, 403, 406. San Bernardino Mountains North of San Gorgonio Pass, Geology of, 319-411. Bernardino Mountains, Califor- nia, 320; glacial features of, 335; structure of, 393 ff.; geological history of, 406; stereogram of, 407; ore deposits of, 409; geo- logic structural sections through, following plates after 411; geo- logical map of, following plates: after 411. Gabriel Range, California, 320; contrasted with San Bernardino Range, 322. Gorgonio Mountain, California, 321, 324; weathering granite at, figure of, 325; rocks of, 347. Gorgonio River, 327; section west of, figure of, 376. San Jacinto Mountains, California, 401. San Pablo Bay region, California, Briones formation of, 137. San Pablo formation, Lower, 134; (Cierbo), on southwest side of Mt. Diablo, 138. San San San San San Pablo group, classification of Briones with, 134. Sandstone, Potato, 344, 374, 395. Santa Ana Mountains, California, New Species from the Cretaceous of, 413-462. Santa Ana sandstone, 344, 378. Santa Margarita, classed under San Pablo group, 134. Index Saragossa quartzite, 344, 350, 357 ff.; figures of, 351, 358, 359. Schaaffhausen, cited, 50. Shear joints, 264. Schists, undifferentiated, of San Bernardino Mountains, 345 ff.; northeast of Beaumont, Califor- nia, 345; of San Gorgonio River, 346; on south side of San Ber- nardino Mountain, 347. Schist series of Cuyamaca region, section through, 186; origin of, 187. Schorlemmer and Roscoe, quoted, 296. Selater, P. L., cited, 99. Scutella breweriana beds, 134. Secondary enrichment, as explana- tion of vein genesis at Cobalt, 279. Segregation according to Soret’s principle, as applied to pyrrho- tites of Friday Mine, 238. Serres, M., and Gervais, P., cited, 75. Ship Mountains, California, absence of fossils in, 2. Silicate and sulphide melts, limited miscibility of in Friday Mine deposit, 239. Siliqua alisoensis, description of, 427; figure of, opp. 454. Sillimanite gneiss of Cuyamaca re- gion, 184. Simonelli, V., cited, 72. Sinum (Sigaretus) trigenarium, de- scription of, 1538; compared with S. scopulorum and 8. trigenar- ium, 153, 154; figures of, opp. 172. Siphonalia dubius, description of, 431; figure of, opp. 456. rodecensis, description, 155; com- pared with §S. danvillensis, 155; figures of, opp. 172. Smart’s Ranch, California, section south of, figure of, 357; section southeast of, figure of, 393. Smith, J. A., Mitchell, S. L., Cooper, W., cited, 50. Smith, J. P., quoted, 189. Snow Creek, California, alluvial fans ab, Oo Ly Spinifer rockymontanus, 6. Spisula falcata brioniana, description of, 152; compared with S. falcata, 152; figures of, opp. 166. Split joints, 266; at Cobalt, 276. Spondylus rugosus, description of, 422; figures of, opp. 440, 446, 448, striatus, description, 4 opp. 444. Stage Station, California, 35. Stanford University, Briones Collee- tion, 135. and 99. oo, figure of, [422] Standachner, F., cited, 74. Stock, Chester, 9, 19, 311. Stonewall quartz diorite of Cuyamaca region, 191. Strand, Young, and Pease, cited, 241. Stromer, E., cited, 76. Stubby Cafion, overthrust on east side, figure of, 399. Subaerial Front, 338. Suballuvial Bench, 338. Sugarloaf Mountain, California, lime- stone of, 355. Sulphide minerals of Friday Mine, relationships between, 219. Sulphide magma, intrusion of at Fri- day mine, 239. Sulphides: at Friday Mine, relation of to rock alteration, 220; rela- tion of to total composition of rocks, 200 ff.; disseminated, of Cuyamaca Basic Intrusion, 218; at Friday Mine, origin of, 224. Targioni-Tozzetti, G., cited, 77. Tchihatcheff, P. A., cited, 49. Tehachapi mountains, California, 324. Tehachapi Pass, California, 324. Tellina sp., description of, 427; figure of, opp. 452. alisoensis, description, 426; com- pared with TT. ashburnerii Gabb, 426; figure of, opp. 452. santana, description, 426; figure of, opp. 452. Tenne, C. A., and Jentzsch, A., cited, 79: Tertiary formations of San Bernar- dino Mountains, 374 ff. Thompson, D’Arcy W., cited, 81. Thompson, R. B., cited, 81. Timiskaming fault, 278. Timiskaming Series, 254. Tiptop Mountain, California, 333. Tivela merriami, description of, 151; figures of, opp. 170. Tolman, C. F., Jr., and Rogers, A. F., cited, .228; quoted, 236, 237. Toula, F., cited, 60, 73. Tower, W. F., cited, 57. Trask, Parker D., 133. Trichecordon, 102. Trigonarca Californica, description, 418; compared with Cucullaea decurtata, 418; figures of, opp. 436. sectilis, description, 419; figures of, opp. 438. excavata, description, 418; com- pared with T. brahminica and T. californica, 418. Trilobites, in Lower Cambrian of Bristol Mountain, 6. Troctolite of Cuyamaca region, de- . scription of, 198. Index Trophon daviesi, description, 155; compared with T. ponderosum and T. earisaensis, 156. gracilis. clarki, description of, 156; compared with Trophon graci- lis, 156; figures of, opp. 170. True, F. W., cited, 31, 60, 61, 62; quoted, 71. Turner, H. W., cited, 374. Turner, W., cited, 79, 89. Ugolini, R., cited, 77. Van Beneden, P. J., cited, 28, 48, 50, 52, 538, 54, 59, 60, 70, 71, 72, 121. Van Dusen Cafion gold, 409. Van Kampen, P. N., cited, 95. Vaqueros formation, canine tooth found in, near Stage Station, California, 35. Vaughan, Francis Edward, 319. Vaughan, T. W., cited, 376. Vein contents at Cobalt, 267; figure showing relation of content to dip of veins, 267. Vein genesis at Cobalt, current theories of, 279 ff.; by diffusion, 295; diffusion in, 288. Vein structures at Cobalt, 268. Venus brioniana, description, 151; compared with V. conradiana Anderson, 151; figure of, opp. 168. Vogt, J. H., cited, 230, 231, 232, 233. Volean Mountain, California, 178. Volutoderma magna, description of, 432; compared with V. gabbi (White), 432; figure of, opp. 460. santana, description, 432; figure of, opp. 458 Wagner, G., cited, 10. Walcott, C. D., cited, 7, 361. Wall rock, assimilation of, 200. Wall rocks, effect of intrusion on, in Cuyamaca region, 208. Wanneria? Cadizensis, 6. Weaver, C. E., cited, 134. Weinschenk, E., cited, 236. Whitman, Alfred R., 253. Whitehead, W. L., cited, 267, 299. Whitewater River, California, catch- ment area at, 341; structure east of, 396. Wild Rose Cafion, mineralization in. 409, Williston, 8S. W., cited, 10, 98. Wilson, E. A., cited, 89, 91. Wortman, J. L., cited, 94. Wyman, J., cited, 74. Young, Pease and Strand, cited, 241 Zalophus, 107. Zimmerman, K. G. H., cited, 49. ERRATA Page 207, footnote 18. For A. §. Ellis read A. J. Ellis. Page 214, figure 2. For 1 inch=30 feet read 1 inch = 50 feet. Page 215, line 7 from bottom. For 11B read 11. Page 217, line 15. For fig. 18 read pl. 10, fig. 3. Page 240, line 29. For Plate 4 read Plate 12. Page 241, lines 16 and 17. For plate 13, figures 3 and 4.... read plate 13, figure 3 and plate 14, figure 1 of the present report, together with two photographs of Sudbury ores (plate 13, figure 2, and plate ja tigune 2) 2. = Page 366, line 25. For Terrace Quartzite read Arrastre Quartzite. Page 387, line 1. For plate 24a read plate 22a. Sie, 1G 12. . Fauna of the Fernando of Los Angeles, by Clarence L. Moody . Notes on the Marine Triassic Reptile Fauna of Spitzbergen, by Carl Wiman ............ . New Mammalian Faunas from Miocene Sediments near Tehachapi Pass in the UNIVERSITY OF CALIFORNIA PUBLICATIONS— (Continued) A Study of the Skull and Dentition of Bison antiquus Leidy, with Special Reference to Material from the Pacific Coast, by Asa C. Chandler ..............-...2-.--:-se--ceeeeeeseeeeee Faunal Studies in the Cretaceous of the Santa Ana Mountains of Southern scat SeeLNVa Uby eMail Meno ye ae at Ol Se ssccacscckerean ec ecccatucntersepcotstasgeosseccoartiasSvocasctpesanedavaeepoteteea . Tertiary Vertebrate Fauna from the Cedar Mountain Region of Western Nawal: fony? iG lain Chesil ernie sar beer See Be ee Seer A aan i 2 SERS ee cee Seen eee eee hore . Fauna from the Lower Pliocene at Jacalitos Creek and Waltham Cation, Fresno County. California, my-doneen.O: INOm aM x28 tote ccacc-snceoccoceccnonnadhosatetaetaansuenacetepeseeiten . The Pliocene of Middle and Northern California, by Bruce Martin ...........0.222.-.:0--- . Mesozoic and Cenozoic Mactrinae of the Pacific Coast of North America, by Earl BT CMO ee Eel CLL LG aoa Ao Sh ra cadet cae ven tah sa stce weds stavegsb cad gpcienapalpiabsadocouessdeteasixgentete soe Meaeenne . The Stratigraphy and Fauna of the Tejon Eocene of California, by Roy E. Dickerson 1.60 . Relationship of Equus to Pliohippus Suggested by Characters of a New Species .from the Pliocene of California, by John Co Merriam 22... ce ne oe eer ae VOLUME 10 . The Correlation of the Pre-Cambrian Rocks of the Region of the Great Lakes, by Andrew C. Lawson pss rier MUG e ae Ne ee OY os Sa 8 sk SA ae ee eee . A New Mustelid from the Thousand Creek Pliocene of Nevada, by Emerson M. | Bui SALT SUPNRITON Cina Sei A SIRE re Re A oo ee eR eR NR aR KOMEN CIA . The Occurrence of Ore on the Limestone Side of Garnet Zones, by Joseph B. TOV SS Op a BPN 2 SE ee ea eM OE a Sopthernvsierra Nevada, by JohneP.. Buwalda. -.2.cictc..-..-o----0e-cestonenton-cudeontocerazeonens . An American Pliocene Bear, by John C. Merriam, Chester Stock, and Clarence L. “LGD LG etcetera Ia mecha AER ESS al i a a Re ee A RCP . Mammalian Remains from the Chanae Formation of the Tejon Hills, California, by John C. Merriam. . Mammalian Remains from a Late Tertiary. Formation at Ironside, Oregon, by John C. Merriam. Nee Saati OPI GMEMCOMCIe Ace mie tree ek ae ee ay a A 8 ae ae . Recent Studies on the Skull and Dentition of Nothrotherium from Rancho La Brea, op CUNO SUCH SHOVE SM AMS Gai ee aOR, NUE DR RIS MARI el . Further Observations on the Skull Structure of Mylodont Sloths from Rancho La Homer aro Dyas OH ESLODS LOC an tee ee cs tcakee eS cet aac yetadyctapect tocuce steaetttuneesennecanacaiace cancer eae . Systematic Position of Several American Tertiary Lagomorphs, by Lee Raymond DOG) FEE ASR eater neice Bee BE ee ee ee OnE Sd OMEN me SE Ee eee aL aM AOR WA . New Fossil Corals from the Pacific Coast, by Jorgen O. Nomlangd ...........----c-seeceee--00" . The Etchegoin Pliocene of Middle California, by Jorgen O. Nomland ._._..WWW..22..-.0.-- . Age of Strata Referred to the Ellensburg Formation in the White Bluffs of the Columbia River, by John C. Merriam and John P. Buwalda .....2.22..21--.-..2c:ecseeeeseeseee= . Structure of the Pes in Mylodon harlani, by Chester Stock -......2222....2:.-:cescseceesseeceeeeeeee , An Extinct Toad from Rancho La Brea, by Charles Lewis Camp .........-.----s-s------1see0 . Fauna of the Santa Margarita Beds in the North Coalinga Region of California, by TCE MONO TMPAT Chex... sc ARe, tN Les ae aes ee ne . Minerals Associated with the Crystalline Limestone at Crestmore, Riverside County, Comtormmay by. arthur Os Mallets. 28 as fe es a ee ee ee . The Geology and Ore Deposits of the Leona Rhyolite, by Clifton W. Clark ...............-.- . The Breecias of the Mariposa Formation in the Vicinity of Colfax, California, by REP UDOTIC OMT gO OC Vrrana tetera aco ea casas tata acess ae cbc eek cee wa castes, Mea owe tg ck . Relationships of Pliocene Mammalian Faunas from the Pacific Coast and Great Basin Enoviuces. of North America, by, John; C., Merriam... 0c. .cth tt. . Anticlines near Sunshine, Park County, Wyoming, by C. L. Moody and N, L. Talia- TESTS fe Sue Bc ee ce Reece cop es metas te ne Sl Islet ry OE ae Oe RMS se . The Pleistocene Fauna of Hawver Cave, by Chester Stock .........-1--c-::-csssccesseesscseeeneetenee . Evidence of Mammalian Palaeontology Relating to the Age of Lake Lahontan, by Pye aw olen on es eee Se dees CAR to, ok Na RC pie rae . New Mammalia from the Idaho Formation, by John C, Merriam. - Note on the Systematic Position of the Wolves of the Canis Dirus Group, by John C. Merriam. . New Puma-like Cat from Rancho La Brea, by John C. Merriam, DOP pam we syA ATS) 1) ONO \CONCL! onc shseccocuncha Peete 120) odobecuonancvchusnsaeddasetibeulsascslsbyoecsssitass ar 99 Rebound Theory, by Andrew C, Lawson .......-..-s-sovs--nsss-ssecsssnecnssnerntenssnnceennsrsanneenennenenes s VOLUME 13 = 1. Lower and Middle Cambrian Formations of the Mohave Desert, by Clifton W. Clark ee 2. Notes on Peccary Remains from Rancho La Brea, by John C. Merriam and Chester ~ re _ 10. . The Franciscan Sandstone: by E. F. Davis Bhi ec eS SS ibe , A Cestraciont Spine from the Middle Triassic of Nevada, by Pirie Davee =a . Tertiary Mammalian Faunas of the Mohave Desert, by John C. Merriam ....... . Geology of a Part of the Santa Ynez River District, Santa Barbara Coun aA . Cretaceous and Cenozoic Hchinoidea of the Pacific Coast, by W. S. W. Kew....... . An Outline of Progress in Palaeontological Research on the Pacifie Woast, by iene . Early Tertiary Vertebrate Fauna from the Southern Coast Ranges of Caleone . Extinct Vertebrate Faunas from the Badlands of Bautista Creek and San Timoteo . A Mounted Skeleton of Mylodon harlani, by Chester Stock ......-2.--.--.-seoscessseoseensrenee= . The Mobility of the Coast Ranges of California. An Exploitation of the Elastie i . Note on an Hipparion Tooth from the Siestan Deposits of the Baas Hills, Cali- . Geology of the Cuyamaca Region of California, with eel reference to the origin a . Genesis of the Ores of the Cobalt District, Ontario, Canada, by Alfred R. Whitman. 80 . A Marsupial from the John Day Oligocene of Logan Butte, Hastern Oregon, by . Geology of San Bernardino Mountains North of San Gorgonio Pass, by Francis = “VOLUME 11 The San Lorenzo Series of Middle California. A Stratigraphic and P Study of the San Lorenzo Oligocene Series of the General Region Diablo, ‘California, by Brucesiuh Clark eo eee eee eee The Radiolarian Cherts of the Franciscan Group, by H. F. Davis Seeceepeepes VOLUME 12 California, by William 'S.\ W.. Ko@W: s,..cccsce-soscpescesnsese- ne Seve ce arene eee ee | FR Es wi 22 lr . ctcogtecden crnnac cn by Chester Stock -.,-.2.2-ascopcenenccscasnnsecoccancencnetegeacssdpeencased te eee eR ee md Cafion, Southern California, by Childs Prick 20-2 ---cscs:cccc-cnteesso =e ees Stock. forina, by Chester Stock. “ANOS: 2 and Bin ONO COVER \.nsc-2ca----secesencccccentece eee cee sono feceseencese as ee : of the nickeliferous pyrrhotite, by F. S. Hudson ........--...2-----2:-----c--ecasennesnanesnennsenoree a a4 Chester Stock and Eustace:L. Purlong =......2.250 ore eee =i Bidward) Varig, occ apes ee ee New Species from the Cretaceous of the Santa Ana Mountains, California, by: K. iia Pare lear ones cece ee aan See cae sabe acc ene Sa ee ANOS wae oh Pei ai ee : . | ay oi. + - ww ae ; ih hy) heh i ae . ‘ iT raat ee 4 4 bey Blea » ‘i ce i a 1 7 ‘ yee ia, f a pen uy tae ane} ua 7 ‘ay: ; Pia Lue mal q oh i ff iy I i ne ary, on tea i er ha: Y) Ak MaSakiacmun release Ta Lebar Ee iy he pene shar. Tare | ya anand DoT ORTH S AR ypc e. A abet 2 Va iia aa. Le m8, ae | f BY Hy ae Ne ass Me nahh’ > bill pi etevererwe tan f THY Pan Xe NH aang nb toy Le Ak ey a2 “eo af’ 2 AL En = ae , a ‘ LT be Ra ‘s | 2 o : > . q “Ah NS ~une® ASR Wg cReERe oe mS aL. peaBA, a Pace e ybAr.~, atts’ Ar, Man hen S aa, lee Labeda! oh Mme AANS) Cl Sea, A Pra. say ] TA TLY A p40) Bain Bom MALE One MIAARRS GEES i treat-a ste.) anni bhe. ta he rn» nr “. 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