35° 



WALTER C. MENDENHALL 



exist, at least one district anticline with a northeast-southwest axis 

 having been observed half a mile south of the well. 



No attempt was made to measure the thickness of these beds, but 

 the buff clays in the middle Carrizo Valley must aggregate i,ooo feet 

 or more, and the beds with a distinctly reddish tone, which are more 

 prominent above Carrizo Station and southeast of Carrizo Mountain, 

 overlie them. The oil well at Yuma starts in sandy strata which 

 appear to be stratigraphically higher than the reddish clays, and at 



Fig. 8. — Old water-line marking the shore of Lake Cahuilla west of Coachella. 



the time of our work in January, 1904, had penetrated over 700 feet 

 of alternating sandstone, shale, gypsum, and shell beds.' The thick- 

 ness of the basal conglomerate on either side of Carrizo Mountain 

 is about 200 feet, as indicated in the generahzed sections of Garnet 

 Canyon (Fig. 10). 



Superficial deposits. — ^The shale bluffs along Carrizo Creek, 50 to 

 100 feet high, are capped in many cases by a deposit of river cobbles 

 three to ten feet in thickness. These cobbles are distributed over 

 practically all of the lower shale hills within the valley whose tops 

 are broad enough to retain the alluvium. Dissection has been so 



I This well was afterward deepened to about 1,200 feet, but the full record is 

 not available. 



