The Valley of the South 265 



with water, was called by the early Spanish settlers a "cienaga," 

 a name which has persisted to our time. 



The Santa Ana an "Antecedent" River 



The Santa Ana River originates far in the San Bernardino 

 Mountains. It is a torrential stream even in its upper reaches 

 during the seasons of heavy precipitation, and it has cut a deep 

 canyon in hard rocks. The stream makes a tremendous fall to 

 the plain of the San Bernardino Basin where its waters spread 

 over a broad alluvial fan or apron. This is the Upper Santa 

 Ana Wash, a rough expanse of boulders, gravel, sand and silt 

 over which flood waters surge with great force. In a similar 

 manner the waters of Lytle Creek, El Cajon Canyon, Mill 

 Creek, and San Timoteo Canyon enter upon the Basin plain 

 over alluvial fans or washes, and join with the waters of the 

 Santa Ana above the Bunker Hill Dike. Below the "dike" and 

 before the river enters the great canyon that has been cut 

 through the north end of the Santa Ana Mountains it is joined 

 by the waters of Temescal Canyon from the south, and Chino 

 Creek and numerous smaller streams from the north. Below 

 the dike the river winds among granitic hills near Riverside, 

 and 2 5 miles below enters the Narrows at Rinc,on, where begins 

 the canyon through which the river flows for 15 miles, when 

 it debouches upon the Downey Plain before crossing the Santa 

 Ana Coastal Plain to the ocean. 



Below the Bunker Hill Dike the waters during much of the 

 year sink into the porous gravels and the river's bed becomes a 

 dry streak of gravel and sand. In flood seasons it is a wild and 

 destructive raging torrent. In times past it has meandered over 

 a wide terrane. Terrace benches and eroded channels on the 

 plain of the Cucamonga Valley give evidence that the river was 

 there during a time of earlier meandering. The middle basin 

 is interrupted by protrusions of granite bed-rock. The granite 

 floor extends along the southern part of the basin from Colton 

 to Corona. Since Fernando time, when the older alluvial de- 



