KAWSOH MOUNTAINS. 767 



Ancylus undulatus. 

 Melania sculptilis. 

 Melania subsculpt'Ms. 

 Splimrum rugosum. 

 Sphcerum f IdaJioense. 



They are all of decidedly fresh-water types, and have been referred 

 by Professor Meek to the Miocene or later formations, but on structural 

 grounds, tlie reasons of which will be found in Volume I of this series, they 

 are regarded with but little hesitation as belonging to the Miocene age. 



Mr. B. E. Brewster, who has analyzed this limestone from Fossil Hill, 

 reports the following composition : 



Insoluble residue - - 7.385 



Alumina - - 0.802 



Iron 0.684 



Lime - - - 48.525 



Magnesia 2.464 



Carbonic acid 40.838 



Phosphoric acid 0.161 



100.859 



The underlying marls, grits, and sands pass into each other by almost 

 imperceptible gradations, and are all characterized by light colors and fria- 

 ble textures. 



Throughout the beds of infusorial silica, there is a general tendency to 

 fine stratification, especially where rendered impure by argillaceous mate- 

 rial, the purer and whiter beds usually underlying a series of yellow, more 

 or less earthy ones near the contact of the overlying grits. The perfectly 

 white bed has the color, texture, compactness, and general appearance of 

 chalk. It is quite sofr, cutting easily with the knife. It cleaves strongly 

 to the tongue, and to the touch has the slight roughness of chalk, soiling 

 the fingers. A number of specimens from different localit'es gave off no 

 effervescence when treated with acid, although the overlying sand and grits 

 and underlying tufas usually indicated the presence of some soluble carbon- 



