CARBONIFEROUS 301 



physical conditions in these two adjacent provinces must have been very 

 different. It shonld also be noted that the entire Yukon Upper Carbon- 

 iferous includes only a few hundred feet of strata, while the supposed 

 equivalent terrains in the Copper Eiver are over 6,000 feet in thickness. 



East of the area occupied by the Mankomen and in the Tanana and 

 White River basins some limestones carrying Upper Carboniferous fossils 

 have been found. Schrader^^- has divided these into two divisions — a 

 lower, which he called the Suslota formation, and an tapper, which he 

 called the ISTabesna formation. The latter has been traced eastward into 

 the White Eiver basin, where they are conformably overlaid by Triassic 

 argillites.^^^ 



The Canadian geologists Keele and Camsell report a limestone between 

 tlie Stewart and Peele rivers, nearly east of the Nation Eiver localities, 

 wliich, judging from the lithological description given by them, is prob- 

 ably the eastern extension of the upper limestone member of the Yukon 

 Carboniferous section. This horizon is described as a "massive granular 

 limestone containing fossils,"^^* but no collection appears to have been 

 made. Keele refers this limestone to the Upper Paleozoic, and states 

 that "it is a mass of white bedded crystalline limestone forming the 

 greater portion of a mountain group."^^^ 



Carboniferous fossils were first reported from northern British Colum- 

 bia by Dawson^^" in a siliceoiis crystalline limestone series which occurs 

 on Tagish lake. Dawson correlated this limestone with the Cache Creek 

 series, both because of lithologic similarity and because of the presence of 

 Fusulina.^'-^ As in a later report Dawson^* shows that in its typical 

 development the Cache Creek includes 10,000 and possibly 15,000 feet of 

 strata and may embrace some Devonian rocks, it is evident that no de- 

 tailed correlation with the Yukon section can be made. Later investiga- 

 tors in this field have followed Dawson in correlations. Gwillim,"® who 



1" W. C. Mendenhall and F. C. Schrader : The mineral resources of the Wrangell dis- 

 trict. Professional paper no. 1.5, V. S. Geological Survey, pp. 46-47. 



"' Alfred H. Brooks : A reconnaissance from Pyramid harhor to Eagle City. Twenty- 

 first Annual Report, U. S. Geological Survey, part ii, p. 359. 



u' Canadian Geological Survey, vol. 16, part CC, 1906, p. 16. 



"= Ibid., part C, p. 14. 



^0 George M. Dawson : Report on an exploration in the Yulson district. Northwest 

 Territory. Geological Survey of Canada, Annual Report, 1887, part B, pp. 170B-171B. 



"'In a footnote Dawson says (opus cited, p. 171B) : "No critical examination of these 

 fossils has yet been made, but they appear referable to Fusiilina rolusta (Meek), found 

 in California." 



"5 George M. Dawson : Report on the Kamaloop map sheet, British Columbia. Annual 

 Report of the Geological Survey of Canada, new series, vol. vii, 1894, p. 46B. 



"^ .T. C. Gwillim : Report on the Atlin mining district, British Columbia. Annual Re- 

 port of the Geological Survey of Canada, vol. xii, 1899, pp. 15B-20B. 



