The Sierra Nevada Range 



169 



and around its curving southern part. The Sierra block was 

 uplifted and tilted toward the southwest, and the block adjoin- 

 ing it on the east sank relatively. The relative movement is 

 shown in the idealized drawing (fig. 53). The magnitude of 

 the displacement, called the "throw," may be inferred from the 

 great height of the eastern escarpment. This in the vicinity 

 of Owens Lake reaches a maximum of not less than 8,000 feet. 

 The great dislocation at the eastern base of the Sierra 

 Nevada should not be regarded as an isolated case. Most of the 

 mountain ranges that traverse the Great Basin are bounded by 

 somewhat similar faults or fractures. The Sierra Nevada is but 



OWE.NS 

 VALLEY 



After F. E. Matthes, U. S. Geol. Survey 



FIG. 53. Generalized diagram of tilted Sierra block. The great fault 

 fractures that separate the Sierra block from the Owens Valley block on the 

 east are shown by a single line, and the relative directions in which the two 

 blocks have sheared past each other are indicated by arrows. 



one, the westernmost, of a vast number of more or less closely 

 related block ranges. The Sierra Nevada is, however, far and 

 away the longest and highest of them all. It is one of the great- 

 est block ranges in the world. 



The reader may naturally wonder what is the cause of so 

 profound a phenomenon as the uplifting of a great mountain 

 range. The cause is not known. What has happened we 

 know. The effects are seen in the rocks. Deep-seated forces 

 of tremendous power from the depths of the earth's interior 

 apparently found expression in the upheaval of large segments 

 of the earth's crust, and molten rock in immense volume was 



