116 Cincinnati Society of Natural History. 
He estimated the thickness of this Pliocene lake strata, which he 
called the Niobrara Pliocene exposed in Wyoming, at from 1,200 to 
1,500 feet. : 
The beds are found lying unconformably upon the older uplifted 
strata, and’ overlapping the area of the Miocene basin. South of the 
Union Pacific Railroad, they occur abutting against Mesozoic forma- 
tions; just north of Granite Canon, they lie next the Archaean mass ; 
and a short distance beyond, at the mouth of Crow Creek canon, are 
found essentially horizontal against nearly vertical Paleozoic lime- 
stones. From Crow creek, northward, they may be seen resting direct- 
ly upon every formation, from the Archean to the Fox Hills Group. 
The strata consists of marls, clays, coarse and fine sandstones, con- 
glomerates, with some nearly pure limestones. Fine, marly sand- 
stones are the predominant beds. | 
Overlying the Pliocene lake deposits on Sybille creek and its tribu- 
taries, and in the region of Chugwater and Pebble creeks, there occur 
beds of coarse and fine conglomerate, having a thickness of 300 or 400 
feet. These beds have been called the Wyoming Conglomerate. 
In North Park, Pliocene beds lie unconformably upon the older 
rocks, resting in places against every formation from Archzean to the 
top of the Cretaceous, and are seen in undisturbed condition resting 
against the basalts. They extend over the entire Park basin, giving 
it the level, prairie-like aspect, which it presents from all the higher | 
elevations. 
He referred the Tertiary beds in the eroded basins and valleys worn 
out in the rhyolité in the Toyabe range of the Nevada basin, and 
noticable on Silver and Boone creeks to the Truckee Miocene. 
S. F. Emmons found the same formation in the valley of Reese 
river, near Ravenswood Peak, along the foot hills, both to the east 
and west of the Soldier’s Spring Valley basin, in the low depression of 
Indian valley, and in the re-entering bay north of Black Canon, with 
a thickness of over 700 feet. : 
The Truckee Miocene is so named from Truckee range, Nevada, 
which extends in a north and south line for 72 miles, and consists, for 
the greater part of the distance, of a single narrow ridge, barely more 
than 5 miles from base to base, but widening considerably at the 
southern end, where it is made up of broad fields of Tertiary eruptive 
rocks, 
Alfred R. C. Selwyn said* that between Blackwater and Stewart’s 
* Geo. Sur. of Canada. 
ee 
