438 University of California Publications. [Geology 



deposit. The age of the beds is not known but it is probable 

 that they are early Tertiary. The second formation of stratified 

 rocks is well exposed in the vicinity of Sullivan's station and 

 thence up "White Rock Creek. It is probably stratigraphically 

 above the sandstone and conglomerate formation of Cache Creek 

 but this was not certainly determined. The formation is almost 

 wholly made up of regularly stratified volcanic tuffs and agglom- 

 erates, well cemented, but there are with these near Sullivan's 

 station some beds of greenish gray sandstone which may be com- 

 posed only in part of volcanic ash. These stratified tuffs and 

 agglomerates lie in a well marked syncline, the axis of which 

 pitches to the northeast. The formation lies chiefly in the coun- 

 try between White Rock Creek and Cache Creek, but the nose 

 of the syncline above referred to crosses "White Rock Creek, 

 toward the west, and in this direction one passes in a few hun- 

 dred yards from the tuffs to the underlying rocks of the Bed- 

 rock Complex. The dip of the strata on the southern limb of 

 the syncline, near Sullivan's, is from 25° to 30°. 



The most interesting feature of these superjacent formations 

 is their degree of deformation, and the evidence that they thus 

 afford that orogenic movements have occurred in the southern 

 end of the Sierra Nevada which seem not to have affected the 

 same series in the middle and northern part of the range. That 

 is to say, while the superjacent series in middle and northern 

 California have been profoundly faulted by the movements 

 which gave rise to the Sierra Nevada tilted block, there appears 

 to have been no folding of such rocks ; while here on the north 

 side of the east end of Tehaehapi Valley the evidence of flexure 

 is marked. 



Outlets of Tehaehapi Valley. — Perhaps the most remarkable 

 feature of Tehaehapi V alley is the fact that it has two outlets. 

 Both of these are incisive stream gorges cut in the granite rocks 

 of the Bed-rock Complex. One drains the western portion of the 

 valley to the Great Valley and is occupied by Tehaehapi Creek 

 which leaves the valley at its northwest corner. The other drains 

 the eastern part of the valley to Mohave Desert. The Tehaehapi 

 Creek gorge has a higher grade than that leading out to Mohave, 

 carries more water and is more sharply cut. The canon draining 



