1902.] HATCHER — OLIGOCENE AND MIOCENE DEPOSITS. 123 



present region of the Black Hills and was tributary to a much 

 larger river coming from the southwest. These sandstone lenses 

 appear to converge and unite as one proceeds toward White River, 

 like the tributaries of recent streams. I am at a loss to understand 

 how these greatly elongated sandstone lenses, confined laterally to 

 at most only a few hundred yards in breadth, and necessitating the 

 presence of strong currents, could have been deposited in the bot- 

 tom of a great lake. For they appear not only to extend quite 

 across the entire region which this lake has been supposed to have 

 occupied, but these or very similar sandstones are found at inter- 

 vals throughout the entire vertical and lateral extent of the beds, 

 although as one recedes eastward from the western border they 

 become less frequent and of finer grain. Such difficulties as those 

 just mentioned, together with others to be referred to later, long 

 ago demonstrated to the present writer the untenable nature of 

 the lake theory as to the origin of these deposits. 



If these beds had their origin in a great lake it may very natu- 

 rally be asked. Where are the remains of the aquatic fauna which a 

 lake of such dimensions may very reasonably be supposed to have 

 contained ? The reply has been made, and will be forthcoming 

 from advocates of the lake theory, that the waters of this great lake 

 were of such a saline or alkaline nature that it was incapable of 

 supporting life. Hence the absence of the remains of aquatic 

 animals. But I shall show presently that such bodies of water as 

 did exist in this region during the deposition of these beds were 

 not only not of such a nature, but that they were eminently fitted 

 for the support of aquatic life and did in fact support such life, both 

 plant and animal, in great abundance. 



Again, if a lake deposit, how did the remains of terrestrial mam- 

 mals and reptiles receive their present distribution throughout these 

 beds? It has been maintained by advocates of the lake theory 

 that the fine-grained, banded clays were deposited in the deep and 

 quiet waters of the lake and the sandstone and conglomerate lenses 

 along the shores and about the mouths of tributary streams, while 

 the preservation and distribution of the remains of terrestrial mam- 

 mals and reptiles was accomplished by the drifting about in the 

 lake of dead carcasses brought down by the tributary streams. Such 

 a theory requires conditions which are not only quite unreasonable 

 but unparalleled elsewhere, both in the deposits of the lakes and 

 seas of the present day and those of past geological epochs. Fur- 



