1916] Bmvalda: Miocene Mammalian Faunas from Tehachapi Pass 85 



vertically 2500 to 3000 feet with respect to the adjacent Mojave Desert 

 area. This zone of displacement fractured the strata containing the 

 middle Miocene mammalian remains, so that if there were no other 

 basis for determining the date of the great displacement which gave 

 the southern Sierra Nevada its present orographic features, the lower 

 limit in time would be defined by the upper Miocene age of the younger 

 of the two faunas. This would indicate that the faulting occurred in 

 late Miocene or post-Miocene time. This fact is of interest when it is 

 recalled that some geologists have set earlier dates for the faulting by 

 which the northern Sierra Nevada attained its present elevation above 

 the Great Basin. 



Transmitted April 9, 1915. 



