26 . CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



Mount Diablo Range. Some of these faults may be mentioned 

 in this connection, but will be dealt with later. One of these 

 may be called the Antelope Valley fault and is imperfectly de- 

 scribed by Arnold and Johnson as traversing the northern 

 border of the Antelope Valley. 



Another is the Bitter water fault which crosses the northern 

 end of the Temblor Range, extending in a northeast to south- 

 west direction. 



A third is that described by the same authors as the Temblor 

 fault, cutting obliquely across the range from east to west near 

 the Temblor ranch house. Other minor faults may be noticed 

 from an inspection of the map, but not all of them are well 

 shown in detail on the published maps. 



The San Andreas fault, although it traverses the eastern 

 border of the San Juan district, has had little or no effect 

 upon developing any of the structures to be seen therein, or 

 to be seen in any part of the neighboring region. It clearly 

 is of recent origin and its importance belongs almost entirely 

 to the present epoch and to the human settlement of the coun- 

 try. The amount of horizontal displacement along its course 

 is hardly noticeable. 



Orogenic Blocks. — The breaking up of the Mount Diablo 

 Range into separate blocks, and the divisions recognized by 

 Whitney, have already been referred to. The following sketch 



Figure i. — Diagram showing the en echelon arrangement of the different 

 parts of the Mount DiaMo Range. 



to illustrate the general facts was made use of in an earlier 

 discussion^ of the stratigraphy of the southern Coast Ranges 



Bull. No. 406, U. S. Geological Survey, p. 100, et seq. 

 ^ Unpublished manuscript 1903. See Abstract, 

 Bull. Geol. Soc. Am., Vol. IS, pp. 581-582. 



