LOWER CALIFORNIA 



115 



Lower California and Northern Sonora. Lower 

 California is the southern spur of the coast-range 

 and possibly of the Sierra Nevada, while the plain 

 of Sonora continues the Colorado desert to the 

 south. 



In point of aridity, the northern portion of the 



Fig. 33. Dry Cereus scrub on steep slopes of a gorge, — 

 Mexico. 



peninsula and of the Sonoran coastal shelf compete 

 with the Mohave- Gila region ; it is another land of 

 thirst. The Pacific coast, barren and torrid, shelters 

 a few strips of scattered chaparral in the troughs of 

 the valleys, and occasionally tolerates short fringes of 

 mangrove-bushes on the tidal marshes ; everywhere the 



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