Geologic Guide for the Northern Part of the Peninsular Range Province, Southern California

Abstract

This geologic guide deals with parts of Los Angeles, San Bernardino, Riverside, and San Diego Counties, in southern California, and in effect is a sampling of the geology and mineral deposits in the northern part of the Peninsular Range province. The main route of travel, essentially an elongate loop (fig. 1), begins in downtown Los Angeles, extends eastward to Pomona, and from there extends southeastward to Lake Henshaw via Corona and the Elsinore-Temecula Valley. The return part of the loop trends in a general northerly direction to the San Jacinto Mountains and San Gorgonio Pass, and thence westward to Los Angeles. The entire route is approximately 320 miles long, involves travel over good roads, and can be traversed without undue haste in 2 days. Several points of special interest can be reached by means of short side trips, about 87 miles in aggregate length, that are included in the guide. An additional trip, 82 miles long, has the form of an auxiliary loop through the Escondido-Ramona area, in San Diego County. Both the main tour and the side trips provide excellent opportunities for observation and study of fault phenomena, geomorphic features, and a wide variety of rock types and mineral deposits. Encountered along the main route of travel are the Elsinore and San Jacinto fault zones, the Pala and Rincon pegmatite districts, and the contact metamorphic deposits at Crestmore.