ransome.] The Great Valley. 373 



» 



fornia lies, as is well known, between the two dominant mountain 

 chains of the state, — the Sierra Nevada on the east and the Coast 

 Ranges on the west. It lias a length of about 400 miles, with an 

 approximate average width of 50 miles, thus giving an area of 20,- 

 000 square miles, which is greater than the united area of the states 

 of Vermont and New Hampshire. It forms a long and relatively 

 narrow alluvial plain, in which the eye can rarely detect any 

 departure from a monotonous level surface. The general trend of 

 the valley is northwest and southeast, or parallel with all the main 

 physiographic features of that portion of the state lying north of 

 the 35th parallel of latitude. On any map of California, upon 

 which the alluvial valleys of the more important streams are in- 

 dicated by a separate color,* this general parallelism of mountain 

 ranges, valleys, and coast-line is a very striking characteristic, and 

 one to which there will be frequent occasion to refer. 



As regards the natural features of drainage, the Great Valley is 

 divided into three divisions of approximately equal lengths. The 

 northern division, commonly known as the Sacramento Valley, 

 drains southward through the Sacramento River, the middle divi- 

 sion drains northward through the San Joaquin River, while the 

 southern division has no regular drainage to the sea, the superfluous 

 rainfall, and the water derived from the melting snows of the Sierra, 

 being gathered into shallow lakes surrounded by broad, tule-covered 

 swamps, and there evaporated. The largest of these is Tulare Lake, 

 lying somewhat to the north and west of the middle of this southern 

 portion. Although having no outlet, this lake is separated from 

 the drainage system of the San Joaquin River by a gentle swell of 

 alluvium, so slight, that in seasons of unusual freshets a transient 

 connection is effected between the lake and the San Joaquin River 

 on the north. The exact nature of this connection is rather obscure. 

 According to Fremont, f the water from the lake flows northward 

 into the San Joaquin River. Blake,! on the other hand, records 



*For example, the preliminary geological map issued by the California 

 State Mining Bureau in 1891. 



t Geographical Memoir upon Upper California, Washington, 1848. 



% Pacific R. R. Reports, Vol. V, p. 192. On page 144, however, Blake 

 records a reported flow in the other direction, thus agreeing with Fremont. 



