1902.1 HATCHER — OLIGOCENE AND MIOCENE DEPOSITS. 117 



300 feet of very light-colored, fine-grained, not very hard, 

 but firm and massive sandstones. On account of their 

 usually barren nature they have been neglected by collectors, 

 and very little is known concerning their fauna beyond the 

 fact that toward the top they contain Promerycochoerus. 

 They decrease in thickness very rapidly to the eastward and 

 increase to the westward. 

 2. The Harrison Beds. — These are well shown in the bluffs of 

 all the small streams that head near the summit of Pine 

 Ridge, in the vicinity of Harrison, Nebraska. They are 

 also known to cover a considerable area to the east, west and 

 south of that village, extending well into the State of 

 Wyoming. They are composed of about 200 feet of fine- 

 grained, rather incoherent sandstones, permeated by great 

 numbers of siliceous tubes arranged vertically rather than 

 horizontally. They are further characterized by the presence, 

 often in the greatest abundance, of those peculiar and inter- 

 esting, but as yet not well understood, fossils known as 

 Dsemonelix, and by a considerable variety of fossil mammals 

 belonging to characteristic Miocene genera. They imme- 

 diately and conformably overlie the Monroe Creek beds and 

 pass insensibly into them. Above these come : 

 The Nebraska Beds, of Scott. — These consist of a series of buff- 

 colored sandstones of varying degrees of hardness and un- 

 known thickness, with occasional lasers of siliceous (not 

 calcareous) grits, which protrude as hard, indurated or shelv- 

 ing masses from the underlying and overlying softer materials. 

 These beds are rich in vertebrate fossils, such genera as 

 Cosoryx, Protolabis, Cyclopidius and Merycochoerus pre- 

 dominating. They are represented at various localities along 

 the Niobrara River, south of Harrison, Nebraska, where 

 they are of unknown thickness and immediately overlie the 

 Harrison beds. Toward the south they pass beneath the 

 Ogalalla formation. 

 According to the above classification all the Miocene deposits of 

 this region are referred to the Loup Fork, notwithstanding their 

 great thickness and, in certain localities at least, their apparent con- 

 formity with the underlying Oligocene deposits, and without regard 

 for the fact that throughout the lowermost 500 to 1500 feet of these 

 sediments there is as yet practically no paleontological evidence as 



