28 BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



Crossing the Colorado Desert, IGl kilometers, or 100 miles, in width, 

 the mountains of the Coast Range are reached and miles of desert 

 countiy lower than the ocean are crossed on the way between 

 Monuments Nos. 220 and 224. Lieutenant Gaillard observes: 



Salton and New rivers (temporary channels of the Colorado Desert) present 

 the anomalous condition of two streams parallel to one another and to the axis 

 of lowest depression in their vicinity, the first being about 18 and the second 

 about 8 miles east of this axis, as measured along the Boundary ; the corre- 

 sponding elevations of the surface at each point being +26,' — 7,' and — 16,' 

 respectively, referred to mean sea level, the last marking the lowest point along 

 the entire boundary line. 



Salton and New rivers terniinate in Salton Sea, wdiich, according 

 to Lieutenant Gaillard, " is about 250 or 275 feet below mean sea 

 level." After crossing the north spur of Signal Mountain, a promi- 

 nent peak on the desert south of Laguna Station, "• for about 10 miles 

 the line passes over a bare, rocky, water-washed mesa, about 300 feet 

 above sea level, from which, by a succession of three or four terraces, 

 indescribably bare, jagged, rough, and precipitous, the line in a 

 distance of about 11 miles attains the summit of the Coast Range at 

 an elevation of about 4,500 feet." (Gaillard.) After this abrupt 

 rise from a point below sea level to the crest of the Coast Range, the 

 line slopes quite regularly to the ocean. The east slope of the Coast 

 Range Mountains is abrupt or precipitous throughout Lower Cali- 

 fornia. 



Waters. — The only rivers worthy of the name on the Mexican 

 border of the United States are the Rio Grande and Colorado, both of 

 which are variable and subject to great seasonal fluctuations in the 

 volume of their waters. The Rio Grande usually becomes dry at 

 El Paso after the high rise of May and June, and is frequently low 

 during the winter. The Colorado is likewise subject to annual over- 

 flows from April to June, sometimes breaking through its right 

 (west) bank and spreading out over the Salton region of the Colo- 

 rado Desert, where the only lakes of any magnitude occur. Tliese 

 lakes of course eventually dry up by evaporation; but, for a time, the 

 region becomes green and vegetation luxuriates in the rich surface 

 deposit from the water. Cattle have lately been driven in, and the 

 owners endeavor to make a breach in the Colorado River bank at each 

 annual overflow, and if they succeed the region again becomes 

 flooded through the channels of New and Salton rivers, which causes 

 a fresh crop of forage plants to spring into life. 



Of the lesser streams, ahvays dignified by the title of rivers in the 

 Southwest, the Mimbres crosses the line, flowing south into the Pa- 

 lomas Lakes, toward Lake Guzman in Chihuahua, crossing the Bound- 

 ary at Monument No. 19, about 113 kilometers or 70 miles west of 

 El Paso. Lakes Guzman and Palomas are considerable sheets of 



