40 COXTIUBUTIOXS TO CEXEKAL GEOLOGY, 1913. 



KM) miloslieyond (^apo Beaufort, ami iIkto is .some iciisoii lor tlie holicf that it is i-oiiliniious to tliat point. Tlicsoiitliprn 

 l>()iiii<liiry of tJic formation extends in a southeasterly direction from the coast for alxnit V2 miles, wlien it turns to the 

 soulh. Heyond this the inland extension of the forinaliou luis not. l)een determined. * » » 



No contact helween the Corwin lorraatioti and the CarUoniferous [later determined to be in part Triassic] rocks 

 described occurs witliiu the limits of the area under investigation, though an unconformity is evident from certain 

 beds of conglomerate contiiining pebbles derived froii; tlie Carboniferous. Lilliologically the formation consists of 

 ratlicr thinly liedded shales, siindstunes. conglomerates, and coal beds. Fossil plants occur in tlie shales wherever 

 they have l)een closely examined. * * » The formation throughout presents very little \ariation in lithologic 

 charucter beyond the fact that in some portions of the section tlie shales are more carbonaceous, while in others they 

 are more calcareous. Throughout the section there is nearly the same proportion of sandy beds. 



As already indicated, the Corwin formation reaches the enormotis thiclaiess of over 15,1)00 

 feet and contains forty to fifty coal heds whicli range in thickness from 1 or 2 to over 30 feet, 

 ten beincj over 4 feet tliick and siiitahk^ for miiiiiio-, tlie wliole aggregatuia: at least 150 feet. 



PLANT COLLECTIONS. 



The plant material dhtaitied i'roiu the Corwin forniation is comprised in iiinetoen collections, 

 from as maiw localities, distributed along the coast from Corwm Bluff to Cape Beaufort, a 

 distiiuce of about 140 mUes and apparently representing beds at ilifi'erent horizons throughout 

 the formation. So far as the data at hand indicate, there is little or no variation m the flora 

 tlirough the whole thiclotess of the formation. AVlten the prelmiinary exammation of this mate- 

 rial was made, an<l without knowmg the relative stratigraphic position of any of the collections, 

 a tentative attem])t was made to fix the position in the section of a few of the lots. This attempt, 

 however, was a failure, for certaui collections which it seemed jirobablc belonged near the base 

 were in reality well distributed tlu-ough the section and, for the present at least, the flora must 

 be considered as a unit. As Collier has well said, "It is reasonable to expect some changes in 

 the flora from the base to the top of a formation of such great thickness, but in this case the 

 variation, if it exists, will probably be detected only by the palcobotanist after a critical per- 

 sonal examination of the section." 



As Collier's collection was not the first to be made in the Cape Lisburne region, a brief 

 review of previous collections and the age determinations given to them may be of uiterest. 



Ap[)arently the first to obtaiit material from the Corwin formation was A. Collie, who 

 accompanied Capt. F. W. Beechey on his celebrated voyage to the .Vrctic. He first noted the 

 presence of coal beds at Cape Beaufort and speaks of "carbonized impressions of reeds, both 

 fluted and plain, generally flat," which were taken by William Buckland,' who reported on the 

 material, as mdicating Carboniferous. As already noted. Collier found only Jurassic at Caj^e 

 Beaufort. 



Nearly 50 years jiassed before anything further was known from Cape Ijisburne. From 

 1S84 to about 1SS7 Henry D. Woolfe, while in the employ of the Pacific Steam Whaling Co., 

 made annual visits to the region and sent to the United States National iluseuni a considerable 

 collection of fossil plants. This material was studied by Lesquereux,^ who enumerated the 

 following forms: 



Irites alaskana n. sp. 

 PecopterLs denticulata Heer. 

 Pinus? starat.scliini Heer. 

 Podozamites latijiennis Ileer. 

 Zamites alaskana n. sp. 



Aspidiuin oerstcdi Ileer. 

 Asplenium dick.'^mianum Heer. 

 .\spleiiinm foersteri Deb. and Ett. 

 Haiera i>alniata Heer. 

 Chondrites (iliciformis n. sp. 



Lesquereux concluded th.nt the age of the l)eds w;is probably Neocomian. 



In 1800 II. D. Dumars made a .small collection of jilants from the Corwin coal mine, wliicli 

 came ultimately to the United States National Museum. This collection, together with ail <>f 

 the Woolfe material, was elaliorated by W. M. Fontaine for Lester F. Ward's nionograiih 

 "Status of the Me.sozoic floras of the United States." ^ Fontaine revised and changeil many 



' Zoology of Captain Beccliey's voyage, Geology, p. 173, London, 1839. 

 « r. S. Nat. Mils. I'roo., vol. 10, p. 36, 1887; vol. 11, pp. 31-.3.'i, 1S.S8. 

 ' V. 8. Oeol. Survey Mon. JS, pp. 153-175, I'Is. XXXIX-XLV, 1905. 



