WALCOTT.l WYOMING. 213 



Wind River Mountains is about 200 feet. All the beds bear evidence 

 of deposition in shallow seas or upon beaches or sand flats. * 



Under the head of Quebec group, Prof. Conistock describes some 

 calciferous layers and doloraitic limestones that are conformably super- 

 jacent to the saudstone. In them he found a species of Theca ?, a tri- 

 lobite of the genus Dikelocephalus and Orthis tritonial Fragments of 

 other fossils too imperfectly preserved for identification were found. 2 



If the identifications by Prof. Comstock of the species found in the 

 limestone are correct, that portion of the limestone containing them 

 must be referred to the Upper Cambrian zone. On the map accom- 

 panying the report the "Potsdam" formation is represented along the 

 entire eastern margin of the Wind River Mountains and along the west- 

 ern central portion of the range. A narrow belt of it surrounds Creek 

 Mountain in the northeast of the Snake Indian Reservation, and the 

 Wyoming Mountains to the northwest of the Wind River Range. 



The southern portion of the Sweetwater district in the Wind River 

 Range was visited by Dr. F. M. Endlich in 1877. He found a Lingula, 

 probably Lingula prima, and estimated the thickness of the entire series 

 as varying between 180 and 320 feet. 3 He refers to the Calciferous 

 group a thin series of sharply bedded strata composed of blue lime- 

 stones and blue and yellow dolomite and locally of oolitic dolomite, 

 altogether having a thickness of about 250 feet. 4 These strata are cor- 

 related with those containing Dikelocephalus, etc., discovered by Prof. 

 Comstock in 1874. 



The Teton Mountain district was studied by Prof. Orestes St. John 

 in 1877, and in his report he refers to the work of Prof. Bradley in 1872. 

 Very little is added to the information given by Prof. Bradley of the 

 lower quartzite series, but an important advance is made in the classifi- 

 cation of the rocks of the district by the division of Prof. Bradley's 

 Quebec group into the Upper and Lower Quebec limestone. The Lower 

 Quebec limestone, carrying Conocoryphe aud Dikelocephalus, is de- 

 scribed in detail and separated from the upper limestone carrying 

 Raphistoma, etc. 5 



The line of separation of these two limestones is the line between the 

 Cambrian and Silurian (Ordovician) Systems, and reference will be made 

 to it under the description of the Cambrian rocks of Wyoming. 



Prof. St. John also studied the Buffalo Fork Mountain, east of the 

 Teton Range, and found there the same succession of beds as in the 

 Teton section. Numerous fossils were collected from the limestone over- 

 lying the quartzite. 6 



1 Geological report. Report upon the reconnaissance of northwestern "Wyoming, mado in the sum- 

 mer of 1873, by William A. Jones. 1874, pp. 107, 108. 



2 Op. cit., p. 110. 



3 Report on the geology of the Sweetwater district. U. S. G-eol. Surv. of the Terr., 11th Ann. Rep,, 

 1879, p. 71. 



4 Op. cit, p. 72. 



6 R port of the geological field-work of the Teton Division. U. S. Geol. Surv. of the Terr,, 11th Ann. 

 Rep., 1879, pp. 48 1-483. 

 6 Op. cit., p. 469. 



