DEPRESSIONS BELOW THE SEA-LEVEL. 105 



lations of sand and mud brought down by the Colorado as Mr. Blake sup- 

 posed, the region above the former mouth of that river became a closed 

 basin of salt-water, which afterwards gradually became brackish, and then 

 almost fresh, as shown by the character of the shells found at various points 

 around its margin. Finally', the entire body of water disappeared by evapo- 

 ration, and the region is now an arid desert, surrounded by detrital accu- 

 mulations which slope down, in the form of " washes," from the sides of the 

 enclosing mountains, and which for a distance of about forty miles, meas- 

 ured parallel with the trend of the valley, is depressed below the sea-level to 

 the amount of a hundred feet or more. This deepest portion, however, is 

 not that nearest the Colorado River, but is rather the upper end of the val- 

 ley, the line of the railroad survey sinking to the ocean level not far from 

 Indian Well, then continuing below that level for about forty miles, and 

 finally rising above it again some sixty miles before reaching Fort Yuma.* 

 In view of the facts developed by the recent railroad survey in reference to 

 the position of the depressed area in this desert region, it would appear that 

 the access of the Gulf must have been cut off by an actual rise of the land, 

 and not by the accumulation of debris brought down by the Colorado. 



All that part of California which lies west of the Colorado and north of 

 the San Bernardino Range, as far as the eastern base of the Sierra Nevada, 

 embracing an area of over 30,000 square miles, is but little better than a 

 desert. It is traversed by broken ranges of mountains enclosing valleys, 

 in whose lowest portions are the visible remains of former lakes, now con- 

 verted into alkali-fiats, which become mud-flats during exceptionally wet 

 winters. The only one of these valleys known to be depressed below the 

 sea-level is that forming the sink of the Armagosa River, and which is known 

 as Death Valley, where there is an area of probably forty miles or more in 

 leno-th and ten or twelve in width which is from a hundred to two hundred 

 feet below the level of the sea. As for as known to the writer, this depres- 

 sion and the one previously mentioned, of the Coahuila Valley and its con- 

 tinuation, are the only areas in North America sunk below the sea-level, and 

 not filled with water, for the deepest of the depressions in the Great Basin 

 proper are several thousand feet in elevation at tlieir lowest points. 



* The iilaii so often broached in California of iiumdating this depressed aiea by letting in the waters of the 

 Gulf, and thus redeeming from sterility this portion of the State of California, is one of which the absurdity would 

 become apparent to any one who would take the pains to make himself acquainted with the climatological pecu- 

 liarities of the region in question. It is quite on a par with the project of converting the Sahara into an inland 

 sea by digging a canal so as to give access to the waters of the Mediterranean. 



