352 University of California Publications in Geology [Vol. 13 



schistosity. Pegmatites and other granitic rocks have cut the whole, 

 resulting in a complex mass similar to those described above. 



Small areas of schist are found included in the granites east of 

 Big Morongo and Rattlesnake canons and also outcropping with the 

 granite in the desert to the north. The largest of the latter is on the 

 southeast side of the hill three miles west of Old Woman Springs and 

 another forms the small hills four miles northeast of Rock Corral. 

 Smaller masses are found in the hills west of Means Wells. 



Summary. — A great mass of schists extends northward from the 

 San Gorgonio Pass to Big Morongo Creek and Santa Ana Canon. 

 Because of their great complexity as compared to sediments of ancient 

 date found farther north and because of their association with granites 

 bearing evidence of pre-Cambrian age these rocks might be considered 

 pre-Cambrian. Similar complex structures, however, have been found 

 in certain portions of the old sediments, and this raises a doubt as to 

 the age of the great schist mass. It may all be of the same age as the 

 quartzites, schists, and limestone in the Bear Valley region, or it may 

 all be much older. Again, certain portions may be of the same age 

 and other portions older. 



The Older Sediments 



The old sediments north and northwest of Cienaga Seca Creek 

 embrace, in ascending order, the Arrastre quartzite, the Furnace lime- 

 stone, and the Saragossa quartzite. The floor on which the Arrastre 

 quartzite was laid down has been destroyed by intrusions of granite. 

 Northeast of Horsethief Flat the quartzite is conformably overlain 

 by the Furnace limestone, the whole series dipping 35° to the south- 

 west. Conformably above the limestone lies the Saragossa quartzite, 

 as is clearly shown in a section along the road a mile northeast of 

 Doble, where both are found dipping 20° to the southwest. 



The structure of the region is so involved that the mere position 

 of the limestone and quartzites in space can hardly be considered as 

 proof of their age relationships; i.e., so far as structure is concerned 

 the section as given may be upside down and the apparent order of 

 succession due to an overturn. However, cross-bedding in the Sara- 

 gossa quartzite shows conclusively that the sequence is as stated above, 

 as will be described farther on. 



Arrastre quartzite. — The Arrastre quartzites are the oldest sedi- 

 ments positively identified as such in the region. The general nature 

 of these rocks is best seen in a section northeast of Horsethief Flat, 



