Geology from a Motor Car 367 



from Red Hill at the mouth of Jawbone Canyon through Red- 

 rock Canyon, through which the highway leaves Fremont Val- 

 ley and the Mojave Desert, is picturesque and fascinating. 



Redrock Canyon, as also Last Chance Gulch and Goler 

 Gulch farther east, have their heads on the northwest side of 

 the main range of the El Paso Mountains, and cut through the 

 range in a southeasterly direction, and drain large areas on the 

 side of the mountains farthest from the main valley. They are 

 "antecedent" streams. Their courses were established before 

 the mountains were uplifted across their paths. To the east of 

 the highway about three miles, on Last Chance Gulch, are inter- 

 esting relics of an ancient forest, the remains of a "grove" of 

 petrified trees. 



The Southern Pacific Railroad runs eastward, swinging 

 around the El Paso Mountains. The highway leaves the allu- 

 vial Fremont Valley of the Mojave Desert through Redrock 

 Canyon to the alluvium covered plain of Indian Wells Valley. 

 The northeast end of the El Paso Mountains is composed of 

 granitic rocks. Farther southwest these rocks are overlain by 

 beds of Tertiary sedimentary and volcanic rocks. In Redrock 

 Canyon, both north and south of Ricardo, rather wide and flat 

 basins have been eroded in the comparatively soft and friable 

 sedimentary rocks. However, upon entering the more resis- 

 tant plutonic (volcanic) and metamorphic rocks, which Red- 

 rock, Last Chance and Goler canyons cut through, the canyons 

 both deepen and steepen very perceptibly, the walls becoming 

 in places almost vertical. Their beds become narrow until in 

 some places they are scarcely wide enough for a wagon to pass 

 between the rock walls. To the north the highway passes upon 

 the alluvium-mantled plain which lies north of the El Paso 

 Range. 



Little Lake, 171 miles (El. 3,175 feet) ; Haiwee Reservoirs, 

 187 miles (El. 3,764 feet) ; Olancha, 196 miles (El. 3,649 feet) ; 

 Lone Pine (Mount Whitney station), 217 miles (El. 3,728 

 feet). 



