252 C.W. TOM LIN SON 



meager fauna of the quartzite at Geneva. 1 There is no representa- 

 tive of these quartzites in the section described by Hintze 2 in Salt 

 Lake County, Utah, 75 miles south of Blacksmith Fork. 



The absence of the Swan Peak quartzite from the Blacksmith 

 Fork section is especially notable in view of the fact that it occurs 

 with a thickness of several hundred feet less than 20 miles to the 

 northeast, in the Randolph area, and also less than 20 miles away 

 in the opposite direction, near Geneva. 



The "Ogden quartzite" in the Uinta Range. — In the south slope 

 of the Uinta Range a quartzite attaining a maximum thickness 

 of about 1,100 feet lies between the Mississippian system and the 

 barren Lodore shales (Cambrian ?) . Weeks 3 correlated this forma- 

 tion with that which is called in this paper the Swan Peak quartzite, 

 in the region east of Cache Valley, Utah; and he applied to both 

 formations the same name, "Ogden quartzite." As no fossils have 

 been found in the "Ogden quartzite" in the Uinta Range, the 

 correlation rests on an insecure basis. 



No representative of this quartzite was noted on the north 

 flank of the Uinta Range. 



The sandstone at the base of the Bighorn formation. — The Trenton 

 dolomites in Wyoming for the most part lie directly on the flat- 

 pebble conglomerate series, but locally they are accompanied by a 

 thin basal sandstone carrying a late Black River or early Trenton 

 fauna, including fish remains. 4 This sandstone is correlated with 

 the fish-bearing Harding sandstone of Colorado, 5 which likewise 

 is overlain by dolomites of Trenton age. It is probable, as has 

 usually been considered, that this sandstone member represents an 

 introductory stage of the Trenton submergence rather than that 

 it is a deposit of an earlier submergence, separated by an epoch 

 of erosion from the Trenton proper, as is the case with the Swan 

 Peak and Eureka quartzites. The faunal lists from the Swan 



1 Black welder, loc. tit. uls. 2 Op. tit. 



3 F. B. Weeks, "Stratigraphy and Structure of the Uinta Range," Bull. Geol. Soc^ 

 Amer., XVIII (1907), 436-37, 44 1 - 



4 N. H. Darton, op. tit. (1905), p. 551 ; and Bald Mountain-Dayton Folio, Wyom- 

 ing, Geol. Atlas U.S., Folio No. 141 (1906), p. 4. 



5 N. H. Darton, op. tit. (1905), p. 552; and Folio 141, p. 4. 



