18 THE SALTON SEA. 



fore find that a great deal of the observed difference of level in the shore-line has been due 

 to this same wave-action, inasmuch as there is a general discrepancy of about 15 feet 

 between the two sides of the Sink, the northeastern, the more exposed one, being higher 

 than the southwestern one, which has been sheltered under the lee of the mountains. 

 The shore-line has been regular and unbroken along the northeast side of the former lake, 

 but upon the southwestern one it has come against the mountain walls in several places, 

 and has in general been much more irregular and diversified, the Superstition and other 

 mountain masses having thrust forward as bold promontories. One small group of islets 

 has existed about midway along the northeastern side of the lake, and about 6 miles off- 

 shore when the water was at its highest level. This is the small hill-ridge to the northeast 

 of Durmid Station on the main line of the Southern Pacific Railroad. It still bears unmis- 

 takable signs of having been subjected to the heavy assaults of surf for some considerable 

 period. 



THE DRAINAGE FROM THE COLORADO AND DELTA. 



The main natural drainage lines from the Colorado to the Salton Basin, before the 

 changes brought about by recent engineering operations, have been the Alamo and New 

 River channels. The Alamo was the most direct, but its connection with the Colorado 

 was in general rather obscure and liable to obstruction and obliteration by vegetation and 

 the deposition of silt. The flow of water was intermittent and irregular and only occurred 

 in seasons of extremely high water. The New River flow did not come directly from the 

 Colorado, but partly from the Alamo by way of the Garza and other sloughs, and partly 

 as overflow from the shallow catchment basin of Volcano Lake. This lake was itself 

 filled, in seasons of normal high water, through the channels of the Paredones, the Pes- 

 cadero, and other less clearly defined waterways. Normally the whole efflux from the 

 lake went directly into the Hardy, and so into tidewater, but in seasons of exceptionally 

 high water it would be forced also to right and left — into New River on the one hand and 

 into the lower Pescadero on the other, and so into the lower Hardy and the Gulf. The 

 influence of the tides is noticeable in the Hardy as far as the point of the Cocopah Mountains 

 and has at times been instrumental in forcing a part of this Hardy and Paredones flood- 

 water into the Pattie Basin. 



The Hardy, with its associated sloughs, backwaters, and lagoons, has always occupied 

 the position of relief channel for the flooded and surcharged Delta in times of high water, 

 filling thus a somewhat analogous position to that of the Bahr el Zaraf in the economy of 

 the Upper Nile.' 



Since 1901 the flow of water in the Delta has been greatly changed, as will be detailed 

 later, owing to the various engineering operations carried out by or on behalf of the irri- 

 gation companies and settlers in the Imperial Valley. 



THE WHITEWATER DRAINAGE. 



The Whitewater receives its water through various small tributaries from the south 

 and east slopes of the San Bernardino Mountains. It is an intermittent surface stream, but 

 imdoubtedlyhas a large underflow, as is evidenced by the copious flow from the artesian bores 

 in the Coachella Valley. (Plate 15.) The total length of this stream is not much over 60 

 miles, but its mean gradient is very steep and its occasional floods very violent. (Plate 8a.) 



THE CARRIZO-SAN FELIPE DRAINAGE. 



The combined drainage area of Carrizo and San Felipe Creeks is about 900 square 

 miles, situated in the piedmont district before alluded to, to the west of the Salton Sink. 

 San Felipe Creek rises almost immediately under the escarpment of the main, or coastal, 



' The Physiography of the Nile and its Baain, p. 122, by Capt. H. G. Lyons, Cairo, 1906. 



