"CERATOPS beds" OF WYOMING AND MONTANA 25 1 



Doctor Leidy also described among Doctor Hayden's collections from 

 the lowest beds of the Upper Missouri Lignites near Moreau and 

 Grand rivers, Nebraska, very probably belonging to the horizon of 

 the Judith River group," some vertebrate remains which have been 

 considered Cretaceous types by Cope. 



Hayden's last general statement on the Laramie problem in the 

 introduction to Lesquereux's "Tertiary Flora "^^ indicates similar 

 views, as the following quotations will show: 



The physical conditions under which the sediments of the upper strata 

 of the Fox Hills group were deposited indicated a gradual change, 

 from deep, quiet marine seas to shallow waters, which became at 

 length brackish and finally entirely fresh waters, during which the 

 purely marine invertebrate fauna perished, a brackish and purely 



fresh- water fauna taking its place As we proceed 



southward and westward from the Missouri River, the brackish beds 

 increase in thickness until along the fortieth parallel they become three 

 thousand feet or more, indicating, so far as can be determined, no 

 break in the sequence from the Fox Hills group to the purely fresh- 

 water strata of the Wasatch group The facts as we 



understand them at the present time would seem to warrant this 

 general division, viz: a marine series. Cretaceous; gradually passing up 

 into a brackish- water series, Laramie; gradually passing up into a 

 purely fresh-water series, Wasatch. It is also probable that the brack- 

 ish-water beds on the upper Missouri must be correlated with the 

 Laramie, and that the Wasatch group as now defined and the Fort 

 Union group are identical as a whole, or in part at least. The plants 

 which are recorded in this volume began their existence at the base of 

 the Laramie group and continued through the entire series, brackish 

 and fresh-water. 



Localities on Yellowstone River in Eastern Montana. — Near Glen- 

 dive the erosion of a low anticline has exposed the Pierre shale and 

 overlying rocks in which Barnum Brown records the presence of 

 Triceratops and Trachodont dinosaurs. Leonard has published'^ a 

 detailed section and a list of invertebrates collected in the upper part 

 of the Pierre shale which here has elements of both Pierre and Fox 

 Hills faunas. The sandstones immediately above the Pierre have 

 yielded no marine fossils and apparently belong to the "Ceratops 



"The Judith River formation was then supposed to overlie the Fox Hills. 

 "U. S. Geol. Surv. Terr., Vol. VII, 1878, pp. III-VII. 

 "Bull. U. S. Geol. Survey, No, 316, pp, 195-198. 



