50 Adventures in Scenery 



The Santa Ana is an interesting stream. Its "behavior" is 

 determined by natural conditions. It conforms to the laws 

 that govern all streams. It is crooked for the same reasons that 

 control in all streams. It corrades or cuts down its channel 

 where its gradient is steep and the current swift enough to carry 

 away all the sand and gravel and debris. It aggrades, or builds 

 up, a floodplain when its current is slackened, and it meanders 

 over a plain with lesser fall. Thus it is a meandering and com- 

 paratively sluggish stream over the plain of the San Bernardino 

 Valley and the coastal plain, but hurries with rapid current 

 down the slopes of the San Bernardino Mountains, and across 

 the axis of the Santa Ana Range. Man's behavior combined 

 with the river's behavior under the conditions that prevail gives 

 the river an unique record. A tremendous stream in its upper 

 reaches, it delivers but little water to the sea. As has been indi- 

 cated, water from the river is used repeatedly in its downward 

 course. Its own current is used higher up to generate power 

 to recall the water which has already furnished power, into irri- 

 gation canals for the use of crops. Due to the "lay of the land" 

 and the porous character of the soil it is possible for man to 

 make repeated use of the water. However, by the river's own 

 behavior most of the water is disposed of before it reaches the 

 sea. But little reaches the sea. The granitic rocks of the 

 mountains break up into a porous gravelly soil, and the water, 

 descending from the highlands, is taken up and becomes ground 

 water of the slopes and plain. The river, a raging torrent in its 

 upper courses during the winter or rainy season, becomes a dry 

 gravelly pavement in its lower courses during the dry summer 

 season, and tributary valleys in which torrents rage in winter 

 become dry "arroyos" in summer. 



Remarkable Group of Rivers Descend 

 Western Sierra Slope 



Probably nowhere in the world is there a more remarkable 

 group of rivers than those which flow down the western slope 



