66 



JOHN A. REID 



side, facing Coso Valley, is free from these late volcanics. From 

 Darwin, elevation 4,746 feet, on traveling westward, there comes 

 first a long alluvial slope of about five miles, with small granite knobs 

 and low hills rising slightly above the surface. Fig. 3 gives a view 

 south of Darwin, showing a long eastern spur of the Coso Mountains 

 which extends sufficiently far to show the effects of the faulting along 

 the Coso Valley line. The contrast between the low granite hills 

 and the fault topography of the Darwin Range is very evident. 



Fig. 2. — View of Coso Range looking south from Keeler. Shows east-west profile 

 of range and east fault scarp. The low basalt ridge connecting the Coso and Inyo 

 ranges is seen at left. 



From the upper edge of the alluvial apron, an elevation of 5,200 feet, 

 the granite rises gradually westward for 2 miles to the foot of the 

 fault scarp shown in Fig. 2, at an elevation of approximately 5,500 

 feet. Above this base the range rises about 1,900 feet. The fault 

 scarp itself is less than 1,000 feet, though originally it may have 

 been much more. From the east fault the east-west profile of the 

 range is well shown in Fig. 2, with the gradual merging of the dome 

 into the western valley. The north-south profile, see Fig. 4, is 

 similar, with Coso Peak as the center and highest point. The present 



