SEDIMENTARY ROCKS 



193 



SalmontroTit limestone as originally defined does not include all the De- 

 vonian limestones along the boundary line, and thus the name is not suffi- 

 ciently comprehensive to apply to the beds here described. 



This entire Devono-Cambrian limestone-dolomite group corresponds 

 lithologically very closely with the Paleozoic limestone section described 

 by Prindle^^ as occurring in the Fairbanks Quadrangle, Alaska; in fact, 

 the entire geologic section described in this bulletin resembles in many 

 ways the section along the 141st meridian. The faunas from this Devono- 

 Cambrian group along the 141st meridian appear to correspond some- 

 what closely to those of the Port Clarence limestone/^ according to Dr. 

 E. M. Kindle, who has examined the fossils from both of these regions. 

 The Port Clarence limestones are typically developed in the western part 

 of Seward Peninsula, Alaska, and the faunas of this formation represent 

 the nearest geographic approach of American fossil faunas to those of 

 Asia. 



The fossils obtained from this limestone-dolomite series along the 

 boundary are of particular interest on account of the Cambrian remains 

 as well as the graptolites which they include. Cambrian fossils were 

 found in several localities along the boundary, but had not previously 

 been reported from Yukon Territory, and have been found in only one 

 locality in Alaska, which is situated in Seward Peninsula, over 700 miles 

 to the west.^^ The nearest Canadian locality in which Cambrian fossils 

 are known to have been discovered is on Gravel Eiver, in the !N"orthwest 

 territories, over 400 miles to the southeast.^^ Graptolites are believed to 

 have been previously found in only two localities in Alaska, namely, in the 

 Mount McKinley region^^ and on Porcupine Eiver,^* and had been discov- 

 ered in places in Yukon in only one locality. ^^ 



The Cambrian fossils collected by the writer along the Yukon- Alaska 

 boundary have all been examined by Mr. L. D. Burling, of the Canadian 



2» B. M. Prindle : A geologic reconnaissance of the Fairbanks Quadrangle, Alaska. 

 U. S. Geological Survey, Bull. 525, 1913, pp. 39-47. 



2" A. J. Collier : A reconnaissance of the northwestern portion of Seward Peninsula, 

 Alaska. IJ. S. Geological Survey, Prof. Paper No. 2, 1902, pp. 18-21. 



E. M. Kindle : The faunal succession in the Port Clarence limestone, Alaska. Amer. 

 Jour. Sci., vol. xxxii, Nov., 1911, pp. 335-349. 



31 E. M. Kindle : Ibid., pp. 340-343. 



32 Joseph Keele : A reconnaissance across the Mackenzie Mountains on the Pelly, Ross, 

 and Gravel rivers, Yukon and Northwest territories. Geol. Surv., Canada, No. 1097, 

 1910, pp. 36, 37. 



33 Alfred H, Brooks : The Mount McKinley region, Alaska, with descriptions of the 

 igneous rocks and of the Bonnifleld and Kautishna districts, by L. M. Prindle. U. S. 

 Geological Survey, Prof. Paper No. 70, 1911, pp. 72-73. 



3* E. M. Kindle : Geologic reconnaissance of the Porcupine Valley, Alaska. Bull. Geol. 

 Soc. Am., vol. 19, 1908, pp. 325-326. 

 ss Joseph Keele : Op. cit., p. 35. 



XIII — Bull. Geol. Soc. Am., Vol. 25, 1913 



