972 REPORT OF NATIONAL MUSEUM, 1895. 



points by xong sweeps or reentering- curves, with outlying islands and 

 l)rqjecting- points partly inclosing oval, valley-like basins, is at once 

 suggestive of a partially submerged series of mountain chains. 



"The peninsula is divided by Gabb ^ into three geographical provinces : 

 A southern, extending from Cape St. Lucas to beyond La Paz, char- 

 acterized by irregular granite mountain chains up to 5,000 feet in 

 height, and with deep valleys containing considerable fertile arable 

 land; an intermediate desert region, characterized by table-lauds and 

 flat-topped ridges, with a considerable extent of interior valleys, and 

 with isolated mountain tops and ranges projecting above the general 

 mesa level, which rarely reach an elevation of more than 3,000 to 4,000 

 feet. This region has no running water and springs are very scarce; a 

 high northern portion from 5,000 to 10,000 feet above sea level forming 

 a southern continuation of the mountain region of southern California, 

 which has a number of running streams and large valleys susceptible 

 of cultivation, while the higher portions contain considerable extents 

 of pine forests. 



"The limits of these three provinces are not sharply defined, but may 

 be taken at about I'OO miles in longitudinal extent for the northern, 450 

 miles for the intermediate desert region, and 100 miles for the southern." 



"While from a first glance at existing maps it might appear that the 

 depressions of the Mohave and Colorado deserts and of the Gulf of 

 California were the normal southern extensions of the great depression 

 of the San Juan and Sacramento valleys, and that the Peninsula range 

 was therefore the normal southern continuation of the coast range, 

 there is some reason to be found in its topographical form, and still 

 more, as will be seen later, in its geological structure, for the assumption 

 that the peninsula more properly represents the southern extension of 

 the Sierra Nevada uplift. On this assumption the connection between 

 the two would be aflbrded by the various en echelon ranges known as 

 San Jacinto Mountains, San Bernardino Mountains, etc., lying to the 

 northward, while the southern extension of the Coast range proj^er, cut 

 off' by the reentering angle of the coast between Santa Barbara and 

 Los Angeles, would be represented by the chain of islands, Santa 

 Cataliua, San Clemente, etc., generally known as the Channel Islands, 

 lying off' the coast between Los Angeles and San Diego. 



"To the south of San Diego the mountains come down to the sea and 

 the mesa disappears, being only represented by an occasional patch of 

 later beds which have escaped erosion, as at Sausal and Todos Santos, 

 GO miles south of the boundary. At Cape Colnett, in latitude 31°, a 

 strip of mesa forms the immediate coast and widens southward toward 

 San Quentin, in latitude 30° 30', which is assumed to be about the limit 

 of the northern or mountainous province. From San Quentin south- 



'See article on Lower California. J. Ross Browne's Mineral Resources of the 

 United States, 1868, pp. 630-639. 



