1914] Buwalda: Tertiary Mammal Beds in West-Central Nevada 343 



of fresh water and possibly Miocene in age. . . . The beds of the Esmeralda 

 formation are inclined at most points, dipping usually from 10° to 40°. No 

 absolutely continuous section of the entire series was obtained, but the total 

 thickness may be several thousand feet. 



The base of the series as seen near the coal mines is composed of sandstone 

 chiefly, with some shale, aggregating perhaps 2000 feet. In this terrane occur 

 the coal, the dicotyledonous leaves and most of the fossil shells. 



Above the sandstones is a considerable thickness of buff shales containing 

 at a few points very abundant fossil fish. . . . The top of the series is made up 

 of lacustral marls and white shales, containing fish bones, and at some points 

 these beds are capped by rhyolitic and basaltic lavas and tuffs. There are also 

 some layers of rhyolitic and andesitic tuffs lower down in the formation, and 

 these volcanic layers frequently contain silicified wood. Faulting has displaced 

 the beds at many points, and it is therefore difficult to estimate the entire 

 thickness of the formation. . . . The dicotyledonous leaves from near the coal 

 horizon are being examined by Professor F. H. Knowlton, who makes the fol- 

 lowing provisional statement regarding them: " . . . T, therefore, do not 

 hesitate to say that the plants seem to indicate a middle Tertiary age." 



In the Cedar Mountain region the lacustral members of the 

 Esmeralda formation consist principally of sandstones, shales, calca- 

 reous shales, and cemented tuffs. In lesser amount are conglomerates, 

 limestones, and cherts. The land-laid members are believed to include 

 fang'lomerates. conglomerates, sandstones, and pumiceous tuffs. The 

 formation is predominantly white or light gray in color ; some of the 

 pumiceous beds are red or yellow. 



Distribution. — Esmeralda beds occupy most of both Stewart and 

 southern lone valleys (pi. 34). The areas of these beds in the two 

 valleys are continuous through the depression between the north end 

 of Cedar Mountain and the south end of the Paradise Range. 



From lone Valley the writer has traced the beds southward, through 

 a number of exposures along the east side of Cedar Motmtain. to the 

 Monte Cristo Range, and through this range to the northern end of 

 the Silver Peak Range, Mr. Turner's type locality for the Esmeralda 

 formation. The Esmeralda beds extend northward into northern lone 

 Valley or beyond and into or through Gabbs Valley. 



An area of the beds, containing mammalian remains, occurs at 

 Battle's Well, at the summit of the pass between the northern Pilot 

 Mountains and Table Mountain. This area is probably continuous 

 with the Stewart Valley area on the east. Small patches of similar 

 white beds occur to the west of the pass along the south face of the 

 Gabbs Valley Range, practically to the edge of Soda Springs Valley, 

 toward which they clip. They probably indicate that the Esmeralda 

 beds underlie, protected from erosion, the later detrital deposits floor- 



