232 GEOLOGY OF THE DENYEK BASEST. 



becomes manifestly of interest to analyze critically the grounds upon 

 which the strata of Converse County containing the Ceratops fauna have 

 been referred to the Laramie, and to compare them with the Ceratops- 

 bearing formations of the Denver Basin, whose stratigraphic relations to 

 the Laramie have been described. 



While Professor Marsh has himself given no details of locality in 

 describing species, there appeared in 1893 an article on "The Ceratops beds 

 of Converse County, Wyo.," by J. B. Hatcher, 1 prepared and published 

 with Professor Marsh's approval. The article gives many valuable data 

 concerning the character and position of the strata in question and specially 

 states the reasons for believing them to he true Laramie. 



Converse County lies on the eastern border of Wyoming, as shown in 

 tig. 24 of this volume. The beds are best exposed on the eastern and south- 

 ern borders of a synclinal basin. Near the southeastern limit the ( Jeratops 

 beds dip to the northwest at angles varying from 16° to 29° and rest with 

 apparent conformity on Fox Hills strata, identified by their marine inverte- 

 brate fauna. To the northwest the Ceratops beds become nearly hori- 

 zontal and pass understrata of more recent age, referred to. below. It is 

 important to notice that according to Mr. Hatcher, "the eastern shore of 

 ; the fresh waters, in which the Ceratops beds were deposited, was nearly that 

 of the present border of these beds. The eastern limit of the fresh waters 

 was confined to the western slope of the Black Hills and that chain of 

 minor uplifts connecting them with the Laramie Range to the southwest." 

 If this be true it is plain that the Ceratops "horizon" has not been traced 

 so continuously along the eastern base of the mountains as might be 

 supposed from the statement of Professor Marsh, above quoted. 



The Ceratops beds of Converse County are 3,000 feet in thickness. 

 At the base is a nonfossiliferous, fine-grained, white or yellowish-brown 

 sandstone member, 4(H) feet in thickness. The lower division of 150 feet 

 is well stratified; the upper 250 feet massive in texture. Above this sand- 

 stone comes a complex of sandstones, shales, clays, marls, limestones, and 

 thin, impure lignite beds. It would appear that this sandstone corresponds 

 in general lithological character to the basal sandstone of the Laramie as 



v ' 1 Am.Jour.Sci.,3d series, V..1. XLV. 1893, p. 135. 



