356 The American Geologist. •'"°«' I'-^^s 
THE PEGMATYTE VEINS OF PALA, SAN DIEGO COUNTY.* 
B.v G. A. Waring, Stanford University, California. 
PT.ATES XXII— XXVI. 
Concerning the region with which this paper deals, 
Fairbanks^ has said : "The structure of San Diego county- 
is comparatively simple. Three main divisions might be 
made : the desert region on the east, the Peninsular range 
of crystalline rocks in the middle, and the nearly level mesa 
on the west. The higher mountains are formed wholly of 
ancient crvstalline schists and massive rocks." 
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^'^- _ , ^ % '-^/ /Riverside 
fscondio/o 
5an OiegoCounfy 
£lCajon 
• Dehesa 
F/i^ / SKefch mapof wesfcrn San DifgoCouoi"^ 
It is with this middle divison, or rather the part of it 
lying between Temecula canyon and the Palomares moun- 
tains, that we have to deal. The Palomares mountains are 
composed of mica schists but the lower lying hills and 
mountains of the region are of granite and dioryte, and 
according to the writer's observation the structure is that 
* The writer is indebted to Dr. J. P. Smith, of Stanford University, 
for advice in the preparation of this article. 
t H. W. Fairbanks— Geology of San Diego County; also portions of 
Orange and Bernardino Counties. Elevettih Annual Report of California 
State- Mineralogist, p. 76. 
