THE FLORA OF THE PINE BELT OF THE SAN ANTONIO 

 MOUNTAINS OF SOUTHERN CALIFORNIA 



I. M. JOHNSTON 

 Pomona College, Claremont, California 



(To be continued) 



The San Gabriel Mountains are a well denned division of the 

 southern extension of the Sierra Nevada Range. With the excep- 

 tion of the extreme eastern portion, they lie wholly within the 

 boundaries of Los Angeles County, Californa, and stretch their 

 sixty miles of length as a barrier between the Mojave Desert to 

 their north, and the cooler coastal plain to their south. 



These mountains are composed of granitic rock and are ex- 

 tremety rugged. The sharp peaks, narrow ridges, talus slides 

 and deep labyrinthine cafion are the most conspicuous features 

 of the San Gabriel Mountains. Their cafion are evenly graded 

 and in most cases have fair sized streams. Occasionally one 

 finds small hillside marshes, but the lakes and large cienegas, 

 which are important features in the neighboring San Bernardino 

 and San Jacinto Mountains, are conspicuously lacking. There 

 are a few rich moist slopes, but due, perhaps, to the porous char- 

 acter of the soil, the majority of the ridges are very dry, even on 

 their north slopes. 



The sky line for the most of its length averages about 7000 feet 

 altitude, but at the eastern end, on the Los Angeles-San Ber- 

 nardino county line, it reaches a maximum altitude of 10,080 feet 

 on the summit of Mt. San Antonio (or Old Baldy) . This eastern 

 section, a very natural subdivision of the San Gabriel Moun- 

 tains, has been called the San Antonio Mountains. They can 

 best be limited as that portion of the San Gabriel Mountains 

 which lies east of the bed of the East Fork of San Gabriel River. 



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