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University of California Publications in Geology [Vol. 7 



California and Nevada Railroad. This whole depression, to the 

 very foot of the El Paso Range, is mantled with debris derived 

 from the Sierra Nevada. The northward slope of the El Paso 

 Range is longer and less precipitous than the southward slope, 

 which rapidly falls off to the south into the depression occupied 

 by Kane "dry lake." The southern base of the mountain ridge 

 forms a remarkably even and straight line (pi. 8, fig. 1). Above 

 this base-line the summit peaks rise to altitudes of less than one 

 thousand feet on the west and to more than three thousand 

 feet on the east. The western portion of the mountain mass is 

 separated into two subsidiary ridges by the deeply-incised 

 tributaries of Red Rock Canon and Last Chance Gulch. 



The mountain ridge is cut transverse to its longer axis by 

 three deep and narrow canons, named in order from west to east, 

 Red Rock Canon, Last Chance Gulch, and Goler Gulch. These 

 canons head in the north flank, cross the range, and drain into 

 the Kane depression to its south. There are springs in the beds 

 of these canons which furnish a surface flow for a few hundred 

 yards in places where the bedrock is close to the surface of the 

 stream bed, but in none of them is there a permanent stream 

 with powers of continuous erosion. 



The upper tributaries of the canons, situated in the compara- 

 tively slightly indurated sedimentary beds of the north flank, 

 follow in general the strike of the strata (pi. 8. fig. 2, and 10, 

 fig. 1) parallel to the longer axis of the range, and have excavated 

 rather wide and flat basins both north and south of Ricardo 

 post-office (pi. 9, fig. 1 and fig. 2) in Red Rock Canon. But upon 

 entering the more resistant plutonic and metamorphic rocks, 

 which the canons cut through in directions nearly at right angles 

 to their former courses, the canons both deepen and steepen very 

 perceptibly (pi. 9, fig. 2), becoming in places almost vertical, 

 while their beds narrow until in some places they are scarcely 

 wide enough for a wagon to pass between the rock walls. The 

 precipitous walls and the narrow bed are especially character- 

 istic of Last Chance Gulch. That gulch, too, has an extremely 

 tortuous course where it cuts through the granite. It heads in 

 tributaries on the southern and southeastern slopes of Black 

 Mountain and then extends for several miles in a westerly direc- 



