THE NEW INLAND SEA = 



By Mr Arthur P. Davis 



Assistant Chief Engineer, U. S. Reclamation Service 



MANY centuries ago the Gulf of 

 California extended to a point 

 about 150 miles northwest- 

 ward from its present head. It also ex- 

 tended up the present valley of the 

 Colorado River at least to Yiuna and 

 probably somewhat above. The Colo- 

 rado River, rising in the Wind River 

 Mountains of Wyoming and the Rocky 

 Mountains of Colorado, carved the rocks 

 along its course and brought the result- 

 ing sands and mud down in its swift 

 current, discharging them into the arm 

 of the gulf near Yuma. As this process 

 went on, without cessation, century after 

 century, the valley was gradually filled, 

 a delta built up, over which the river 

 flowed far out into the gulf. It en- 

 croached progressively upon the shores 

 of the gulf until it built up a delta en- 

 tirely across, joining the foothills of the 

 Cocopah Mountains on the western shore. 

 This cut off the head of the gulf, and the 

 arid climate rapidly evaporated the waters 

 thus separated and left an inland depres- 

 sion, which at its lowest point was nearly 

 300 feet below sea-level, f 



The river continued to bring down its 

 load of sediment and to build its delta 

 higher and force it farther into the gulf. 

 Like all such deltaic streams, the channel 

 on the top of the delta is constantly shift- 

 ing, cutting one bank, building up the 

 other.overflowing both banks, and during 

 high water sometimes entirel}^ abandon- 

 ing an old channel for a new one. In this 

 way the river has from time to time flowed 

 into the Salton Sea for some years or 

 centuries, and anon has shifted to the 

 eastward and discharged again into the 

 gulf. This is the general course the 

 river has followed ever since its dis- 

 covery by the Spaniards in the i6th 



century. At high water the river nor- 

 mally overflows its banks in the valley 

 regions all the way from the Grand Can- 

 yon to the Gulf of California. In un- 

 usually high water, such as occurred in 

 1891, the overflow running into the Sal- 

 ton Sink has been sufficient to materially 

 raise the level of the lake and overflow 

 the tracks of the Southern Pacific Rail- 

 way, which are built along its shores. 



the irrigating company responsible 

 for the break 



The ease of diverting the Colorado 

 River near the international line and con- 

 ducting the water through natural chan- 

 nels to the Colorado Desert for irrigation 

 has been recognized for many years, and 

 various attempts to promote this project 

 have been made from time to time, usu- 

 all}', however, without success, owing to 

 the international complications involved. 



About 1 89 1 Mr C. R. Rockwood, a 

 civil engineer, made plans for the con- 

 struction of a headgate in rock at the 

 foot of Pilot Knob, just north of the 

 Mexican line, and of a canal to carry the 

 water to the so-called Alamo River, an 

 ancient channel of the Colorado which, 

 by lapse of centuries, had been nearly 

 filled with sand and sediment. Efforts 

 to promote this project were for nearly 

 10 years unsuccessful, but finally a small 

 amount of money was raised, which, 

 however, was insufficient for the con- 

 struction of the works as planned. The 

 promoters then concluded simply to cut 

 the dirt banks of the river and lead the 

 water by a small canal into an old chan- 

 nel, whence it flowed into the Imperial 

 Valley without additional construction. 

 A cheap wooden headgate was built in 

 the canal near the river and was for a 



* An address to the National Geographic Society, November 23, 1906. 

 t It is estimated that the amount of silt carried by the Lower Colorado River is sufficient 

 to cover 53 square miles one foot deep with dry alluvial soil each year. 



