THE GREAT SIERRA NEVADA FAULT SCARP. 609 

 THE GREAT SIERRA NEVADA FAULT SCARP. 



By HAROLD W. FAIRBANKS, Ph. D. 



ri^HAT portion of California lying east of the crest of the Sierra 

 -L Nevada Mountains has had a remarkable geological history. 

 There are many phenomena to be witnessed in that region which 

 possess much interest aside from their purely scientific aspect, and 

 deserve to be better known than they are at present. The enormous 

 scale on which faulting has taken place, resulting in the precipitous 

 eastern wall of the Sierra Nevadas, and the variety and extent of 

 the comparatively recent volcanic outbursts along the lines of frac- 

 ture, bring the magnitude of geological processes vividly before our 

 eyes. There are probably no better examples of topographic fea- 

 tures due to the elevation and depression of great blocks of the 

 earth's crust, through the formation of faults, to be found in any 

 other portion of the world. From a scenic standpoint, also, the 

 region is unique. The lofty, jagged crest of the Sierras rises over 

 fourteen thousand feet, culminating in Mount Whitney, the highest 

 peak in the United States south of Alaska, while in marked contrast 

 to the ice and snow of these mountain heights are the hot and 

 scorching wastes of Death Valley, which lies but a short distance to 

 the east, depressed over three hundred feet below the level of the 

 sea. Snow-clad mountain and desert sand, mighty earth blocks, vol- 

 canic craters, lava flows, and alkaline lakes — where can be found 

 greater attractions for the student of Nature? 



The Sierra Nevada Mountains, having a length of over three 

 hundred miles and a width of seventy-five miles, consist essentially 

 throughout much of their extent of one great block of the earth's 

 crust, having been elevated along a north-and-south line through a 

 series of movements which have been frequently repeated during a 

 long period of geological time. The block as a whole was not ele- 

 vated, but tilted from the east, so that on that side there is an abrupt 

 wall many thousands of feet in height, while on the west the slope is 

 long and gradual. Owing to this fact it is only when seen from 

 some point at its eastern base that the magnitude of this range of 

 mountains is appreciated. Although the valleys at the eastern foot 

 of the mountains vary from three thousand to six thousand feet in 

 altitude, the wall of rock forming the scarp rises so abruptly and 

 with such colossal proportions that it is absolutely overpowering in 

 its grandeur. To the east and running parallel with the Sierra 

 Nevadas are other giant ranges formed in much the same manner, 

 being only slightly lower but separated from each other by desert 

 valleys. 



VOL. LIT. — 44 



