220 



University of California Publications. 



| Geology 



GENERAL CORRELATION OF VIRGIN VALLEY AND 

 THOUSAND CREEK BEDS ON THE BASIS OF 

 PHYSICAL AND FAUNAE RELATIONSHIPS 

 TO OTHER FORMATIONS OF THE 

 PACIFIC COAST REGION 



Such reference to correlation of the formations of northern 

 Nevada as has appeared in this discussion up to the present 

 time has been based upon either stratigraphic or faunal evidence 

 considered alone. It seems important to consider the relation 

 of these formations to each other, and to other members of the 

 Tertiary system in the Pacific Coast region in the light of the 

 combined evidence from these fields of investigation, in order to 

 see the fragments of the palaeontologic record placed as nearly 

 as possible in their true relative positions. In farther discussion 

 it is desirable to use all of the available means of comparison 

 checked against each other, in the hope that thus combined they 

 may intimately accomplish more than has been possible with any 

 one group alone. 



Relation of Virgin Valley and Thousand Creek Beds to each 

 other. — In the discussion of the geologic relations of the Thou- 

 sand Creek Beds, in Part I of this paper 7 the writer has indicated 

 the difficulties in the way of determining the exact geologic rela- 

 tions of the Virgin Valley and Thousand Creek formations to 

 each other without farther study of this region. An investiga- 

 tion of the territory to the north and east wonld probably furnish 

 the information necessary to make clear the doubtful factors in 

 the physical history. 



The palaeontologic relations of the two formations seem 

 pretty clearly defined. While the writer has constantly held in 

 mind the possibility that a mixture of Miocene and Pleistocene 

 species might result in a determination of the age of the Thous- 

 and Creek Beds as Pliocene, the evidence before us does not 

 seem to indicate that this is the case. A Miocene fauna such as 

 that of Virgin Valley does not seem to be represented in the 



i Merviain, J. C, Univ. Calif. Publ. Bull. Dept. Geol., vol. 6, pp. 45-50, , 

 1910. 



