108 Cincinnati Society of Natural History. 
between Green River station and Bryan and in the escarpments on 
either side of Henry’s Fork at many places. The Tower sandstone is 
well shown in the cliffs at Green River station, and in that vicinity and 
below the mouth of Currant creek. The Tower sandstone is laid down 
unconformably on the Lower Green River Group, the unconformity 
being represented by gentle valleys of erosion. 
The Bridger Group consists of Bad Land sandstones (chiefly green 
sands ) limestones, shells, marls, and concretionary and stratified flints. 
Thickness, 2,000 feet. 
It is well exposed in the vicinity of Fort Bridger, at Church Buttes, 
at Haystack mountain and in the Cameo mountains. An outlying 
patch is found north of the Dry mountains between Vermilion creek 
and Snake river. Unconformity with the beds of the Lower Green 
River Group may be seen in the vicinity of Carter station, but uncon- 
formity with the Upper Green River Group has not been observed. 
The two are separated, however, upon lithological grounds, though the 
plane of demarkation is obscure. The moss agates for which the re- 
gion about Fort Bridger has been noted are from irregular beds and 
aggregations of chalcedony in this Group. 
The Brown’s Park Group consists of sandstones, gravels, limestones, 
concretionary and stratified flints. Unconformable with all under- 
lying rocks. Thickness, 1,800 feet. 
It is well represented at Brown’s Park, in northeastern Utah, and in 
northwestern Colorado. About five miles above the confluence of Snake 
river with the Yampa, the beds may be seen resting unconformably 
against Carboniferous strata, and on going north they may be observed 
to rest unconformably with the Bridger Group. 
In Brown’s Park, it lies in a deep basin of erosion, the bottom and 
sides of which are composed of Uinta sandstone. This basin is in the 
very axis of the Uinta uplift. Its sandstones are Bad Land rocks of 
exceedingly fine texture. In some places there are extensive and _ir- 
regular aggregations of chalcedony. 
The Bishop’s Mt. Conglomerate, which is unconformable by plica; 
tion and erosion with underlying rocks. Thickness, 300 feet. It is 
found on the summits of Bishop and Quien Hornet mountains, and up- 
on various tables in the Uinta mountains. On the north side of Con- 
nor basin, at the head of Sheep creek, this conglomerate has a thickness 
of more than 1,000 feet. It is neither a marine nor lacustrine deposit. 
but a subeerial one. 
Prof. Powell says, witnessing on every hand the accumulation of such 
Pian. 
