TMT^I 1 * 





THE INFUSOEIAL DEPOSITS: m NEVADA. 



227 



Hills, and striking their northern base nearly as far west as Warm Spring 

 Valley ; also near the site of Sam's Station, northwest of Mirage Station, and 

 on the banks of Little Truckee River, between Pyramid and Winnemucca 

 lakes ; also west of Reno Station, on the Central Pacific Railroad, near the 

 boundary of California. The deposits of Warm Spring Valley are obscure, 

 and show no very great thickness of beds. That near Hunter's Station, west 

 of Reno, is an extensive exposure on the right of the railway-cut in approach- 

 ing California, and consists of several hundred feet (certainly as many as 300) 

 of pure-white, pale-bulf, and canary-yellow beds of remarkably pure infusorial 

 earth." # 



The locality on the northeast point of the Kawsoh Mountains was found 

 by Ehrenberg to be very prolific in microscopic forms. The total thickness 

 of the series of grits, fresh-water limestones, and infusorial silica exposed at 

 the northern end of the Kawsoh Mountains is, according to Messrs. Emmons 

 & Hague, about 450 feet. Above this is a heavy deposit of basalt, and under 

 it one of palagonite tufa of over 250 feet in thickness. The infusorial beds 

 are said to have a development of 200 feett 



Another interesting locality is that on Little Truckee River, a few miles 

 above its mouth, also very rich in microscopic organisms, forty-six distinct 

 species of diatoms having been observed in the examination of twenty-five 

 different slides; of these, Ehrenberg classed twenty-eight as Polygastera and 

 eighteen as Pliytolttharia. The thickness of the infusorial mass at this local- 

 ity could not be made out on account of the absence of sufficient exposures. 



The plateaux of the Des Chutes basin, in Oregon, first visited by Fremont, 

 and afterwards by Newberry, are covered by a smooth sheet of basalt, under 

 which is a great thickness of volcanic conglomerate, tufas, and marls, with 



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more or less of infusorial material intercalated. These tufaceous strata are, as 

 Dr. Newberry remarks, cut by the Des Chutes and its tributaries to the depth 

 of more than a thousand feet, without exposing the floor on which they rest. 

 There is no reason to suppose, however, that — as 



lias been often stated 



there is a thickness of 1,200 feet of infusorial rock here. The tufas do indeed 

 exhibit that amount of development, and with horizontal, undisturbed strati- 

 fication. Dr. Newberry, however, does not say that the whole mass is infuso- 

 rial, but that some of the finer varieties are. It would appear highly probable 



* Report of Fortieth Parallel Survey, Vol. I. p. 419. 



t Ehrenberg got, from the information sent him with the specimens, by the Fortieth Parallel Survey, 

 the impression that the thickness of the infusorial strata was a thousand feet. 



