from Meadow Valley Region, S. Nevada. 251 



atively small portion of the great area in which, later 

 Cenozoic deposits are exposed, appears worthy of record 

 as it not only furnishes palseontologic data for correla- 

 tion studies of the Great Basin Tertiaries, but may also 

 be of service in an interpretation of the geologic history 

 of the Grand Canyon of the Colorado. 



Previous Knowledge. 



We are indebted to the reconnaissance study of Spurr^ 

 for the first account of the geologic features of south- 

 eastern Nevada. The observations which Spurr has 

 recorded concerning beds determined as of Pliocene age 

 in the Meadow Valley region will suffice for purposes of 

 the present paper and need only receive attention. 



The group of deposits so determined includes the sedi- 

 mentary series of Meadow Valley typically exposed in 

 the vicinity of Panaca, Lincoln County, Nevada, and 

 discussed in the text of Spurr ^s report although not 

 indicated on the geological reconnaissance map which 

 accompanies the paper. Beds similar in appearance to 

 those occurring in Meadow Valley, but located some 30 

 miles south of Panaca, are mapped as Pliocene, the sedi- 

 ments extending from this point to the south along the 

 western base of the Mormon Range. They are well 

 exposed in the Meadow Valley Wash. Along the Muddy 

 River east of the Mormon Range and in the valley of the 

 Virgin River the sedimentary strata, approaching closely 

 in general appearance those exposed in the Meadow 

 Valley Wash, are regarded by Spurr as probably of 

 Pliocene age. 



With reference to the accumulation of the Pliocene 

 series, Spurr remarks : 



' ' As observed by the writer in the Meadow Valley Wash, they 

 have the appearance of having been deposited in a lake, although 

 it is possible that they represent the valley accumulation of the 

 Colorado River, at a period when the streams of this system occu- 

 pied wide valleys, in which they worked laterally and deposited 

 the material which they derived from the erosion of the mountains, 

 the carrying power of the streams at that time not being equal to 

 the amount of load received. These sediments occupy the older 

 valleys which were eroded in the Paleozoic limestones and in the 



2 Spurr, J. E., op. cit., 1903. 



