828 HISTORICAL GEOLOGY. 



erates formed out of various older stratified rocks, some identified as Car- 

 boniferous by their fossils. The occurrence of eruptive debris in the Laramie 

 beds of other regions has been regarded as a probable sign of Denver age. 

 The jDlants include species not found for the most part in the Lower 

 Laramie. The Denver group has afforded Horned Dinosaurs (Ceratopsids) 

 and other kinds, showing their Mesozoic relations. Ordinary Mammals are 

 absent, and all other evidence of a Tertiary fauna. 



To the Upper Laramie are referred, by Cross, — on the ground of the 

 plants (studied by Knowlton) as well as the eruptive conglomerates and 

 unconformity at base chiefly by erosion, — beds in the Middle Park, and at 

 other localities, from Greeley, Col., to the Raton Mountains in New 

 Mexico ; and beds about Livingston, in Central Montana, called by W. H. 

 Weed the Livingston beds ( U. S. G. S. Bulletin, No. 105, 1893). The latter, 

 as described, have a thickness of 7000 feet, and rest over 1000 feet of Laramie 

 beds, but were deposited, like the Denver, after a time of extensive erosion, 

 and therefore the conformability is not perfect. The group, however, 

 according to Weed, has a brackish-water, oystei'-bearing layer, which is well 

 packed with oyster shells, Laramie-like, at a height of 200 feet above its 

 base, that is, above the plane of extensive erosion. 



In southern Wyoming, along Bitter Creek, in the vicinity of the Union 

 Pacific Railway, near Hallville, Black Butte, Point of Rocks, Rock Spring, 

 and elsewhere, the Laramie contains a number of coal-beds. South of Black 

 Butte there are nine or more distinct coal-beds ; and between two of them 

 were obtained remains of a Horned Dinosaur (Agathaumas of Cope). 



Beds in eastern Wyoming, called by Marsh the " Ceratops beds," are 

 referred, with a query, by Cross to the Upper Laramie, because of the 

 presence of Ceratopsids in both ; but to the Lower, by Marsh. They rest on 

 400 feet of sandstone conformably, and the sandstone directly on Fox Hills 

 beds, and contain no eruptive debris. Besides Horned Dinosaurs of several 

 species, the beds have afforded remains of other Dinosaurs related to the 

 Iguanodon and Megalosaurs, and of Marsupial and Oviparous Mammals. 

 Above the stratum containing the fossils there is a bed of coal, the Shawnee 

 coal-bed, 10 inches thick. 



"Judith River" beds in northern Montana, first described by Hayden 

 and Meek, afford Dinosaurs of the same genera, according to Marsh, as the 

 Ceratops beds, besides many others, including Plesiosaurids ; and also re- 

 mains of Sharks, Chimseroids, Ganoids, and, as other evidence of brackish- 

 water conditions, shells of Ostrea, Anomia, Gorhicula, Corhula, and Gonioh- 

 asis. 



The Fort Union beds, near the border of North Dakota and Montana, have 

 been referred to the Upper Laramie and also to the Tertiary. They are of 

 doubtful relations. 



The most eastern ''Lignitic" beds referred to the Laramie are those of 

 South Dakota, near Moreau River, west of the Missouri, in 101° W., where 

 remains of two Plesiosaurids have been found, Plesiosaiirus occiduus, and 



