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University of California Publications. [Geology 



The largest of these valleys is Tehaehapi, and, as it forms the 

 pass over the mountains for the railways connecting the Great 

 Valley with Southern California, it was the first to attract the 

 attention of the writer. An attempt to get familiar with its 

 features led to the discovery, however, that it was but one of a 

 system of similar valleys which characterize the region. In the 

 country to the west of Tehaehapi lie Brites Valley, Cummings 

 Valley, and Bear Valley. It is the purpose of this paper to give 

 a brief descriptive account of these valleys, to indicate something 

 of their geological history and in so doing suggest at least a 

 partial explanation of their rather unique features. 



TEHACHAPI VALLEY. 



General Features. — Tehaehapi Valley is situated on the sum- 

 mit of that portion of the Sierra Nevada which lies between the 

 southern end of the Great Valley and the Mohave Desert. Its 

 extent from east to west is about 12 miles. Its breadth in its 

 middle part, at the town of Tehaehapi, is about 4^ miles. At 

 its west end it is 6 miles wide and at its extreme east end it 

 narrows to about half a mile. It has thus in ground plan the 

 form of a right angled triangle, the right angle being at the 

 southwest corner of the valley. Its area is about 36 square 

 miles. 



The boundaries of the valley are for the most part bold 

 mountain slopes, which rise to crests at no great distance from 

 the valley. The area of the hydrographic basin in which the val- 

 ley lies is about 130 square miles. From this statement it will 

 be apparent that the streams which flow into the valley from 

 the surrounding mountains are small. The annual rainfall is 

 10| inches. 



Streams. — Of these streams the two largest are on the north 

 side of the valley toward its east end, and are known as Cache 

 Creek and White Kock Creek. Both of these enter Tehaehapi 

 Valley through trumpet-shaped side valleys, which in their stage 

 of geomorphic advancement and in their degree of alluviation 

 are seemingly homologous to, and harmonious with, the main 

 valley to which they are tributary. These tributary valleys are 

 of the nature of embayments in the mountains on the south, and, 



