76 SOUTHERN CALIFORNIA GEOLOGY 



whose most remote provinces have recently and sud- 

 denly been opened to her by canal, motor roads, rail- 

 ways, steamship lines, and airplanes, tying her still 

 more closely to the border states of the Southwest and 

 to the outer provinces of Mexico, Central America, 

 Panama, the Antilles, the Orient and Hawaii. 



GEOGRAPHIC UNITS OF SOUTHERN 

 CALIFORNIA 



I cannot here give detailed descriptions of the many 

 geographic units of Southern California, each of 

 which could make the subject of a paper in itself, but 

 must limit myself to a broad and sweeping picture 

 of them. In no portion of the world of similar area 

 are there so many geographic identities as here. 

 Instead of the few physiographic units of majes- 

 tic proportions as in Northern California, or the far- 

 reaching units of plains, prairies and forest-belts of the 

 eastern portions of our continent, the units are many, 

 are of great variety and are encountered at short inter- 

 vals. The accompanying sketch is an attempt by the 

 writer to show on a very small scale the names and 

 locations of the units of Southern California. (See 

 Plate 1.) 



THE HIGHLANDS 



There are many kinds of highlands in Southern 

 California which occur either in groups or as individ- 

 uals. These vary in size from relatively small, single 

 ranges of the San Pedro Hill and the Verdugo Range 

 types, to gigantic features like the Peninsula Ranges, 

 which extend a thousand miles from Riverside to 

 Cape San Lucas in Lower California. 



Some of these, the minor highlands, are elongated, 

 folded ranges of sedimentary strata, such as the Ven- 



