412 White and Cope—The Green River Group. 
these buttes are composed are approximately horizontal, and 
ley, the strata of the Laramie Group were traced out into the 
country upon either side, and up into the higher lands, includ- 
thickness of coarse sandstone strata, the lower half being more 
i This sandstone 
presents a precipitous front at almost all sides of the irregularly 
Resting directly and conformably upon this sandstone 1S 
mass of light gray fissile caleareous shales which, to one familiar 
with the aspect of the typical shales of the Green River Group, 
at once suggests their identity. These shales are plainly a rem 
