338 WALTER C. MEN DEN HALL 



Imperial was accomplished and the party disbanded. About ten 

 days in all had been spent in the field. 



Early Land Ofiice maps, upon which neither roads nor relief are 

 shown, were at that time the only official maps available, although 

 since then, because of the rapid settlement of the Imperial Valley 

 and the interest created in the region by the partial filling of the 

 Salton Sink, the Geological Survey has issued a Reconnaissance Map 

 which contains some details in the settled parts of the district but 

 is very general in the vicinity of Carrizo and Black mountains, because 

 these masses lie to the west of the area actually surveyed. 



In 1900 and 1901 a number of oil companies were organized to 

 prospect along the west side of the desert, between the base of the 

 Santa Rosa Mountains and the Mexican line, and a number of 

 engineers entered the district in the employ of these companies. 

 Mr. I. A. Hubon and Mr. C. S. Alverson, of San Diego, were among 

 these, and they collected data which, when assembled in a sketch 

 niap at Dr. Bowers' request, served to guide us in our field-work. 

 From all these sources and from some sketches made by the writer 

 the accompanying generalized map (Fig. i) has been prepared. It 

 does not pretend to topographic accuracy but indicates merely 

 general geographic relations and general topographic facts without 

 detail. 



GEOGRAPHY 



Black and Carrizo mountains, known also as Fish Creek and 

 Coyote mountains, are eastern outliers of the Peninsula Range that 

 separates the depression occupied in part by the Gulf of California 

 from the Pacific Ocean. They are in southeastern Cahfornia near 

 the western edge of the Colorado Desert, and from fifteen to thirty 

 miles north of the international boundary. East of them the Colorado 

 Desert, much of it below sea-level, extends to the Colorado River, 

 while to the west low ridges extend to the base of the main Peninsula 

 Range. 



The two masses are separated by the valley of Carrizo Creek. 

 This stream rises in Mexico, flows north for several miles, through 

 a high valley in the Peninsular Mountains, then descends to the 

 Desert level through a precipitous canyon. Nearly all of that part 

 of its channel that lies within the desert is dry except during rare 



