288 GUIDEBOOK OF THE WESTERN UNITED STATES 
Just west of Dixieland sea level is reached on an up slope of the 
desert which continues westward to the foot of the mountains. 
Three miles west of Dixieland the beach of old Lake Cahuilla is 
crossed at about 40 feet above sea level. This lake occupied the 
Salton Basin sufficiently long to develop well-marked strand features. 
(See p. 253.) At Plaster City is a mill making plaster of paris from 
gypsum mined from large deposits in Fish Creek Mountain, 26 miles 
northwest, and brought by a branch railroad. The deposit is inter- 
bedded in strata of Tertiary age, and near by is a considerable body 
of the mineral celestite (strontium sulphate), also included in the 
sedimentary succession. 
Halfway to Coyote Wells a low ridge is crossed showing tilted clay 
and sand of Tertiary age, truncated and capped by a thin mantle 
of sand and gravel. This ridge crosses the valley and rises into 
Coyote Mountain, which is conspicuous to the north. This mountain 
and Fish Creek Mountain, just beyond, consist mainly of a core of 
anite and marble and other metamorphic rocks, closely folded and 
encircled by Tertiary and later strata. The marble, which may be 
of Paleozoic age, is penetrated and metamorphosed by the granite. 
. Itis mostly of blue-gray color and has been quarried to a small extent 
at the east end of Coyote Mountain. Some portions contain con- 
Ss. 
Vall 
Ally 
oO ao Mile 
. e oa ) Ke i 
Figure 70.—Section across aera Mountain, Calif., near Alverson and Garnett Can- 
yons. _ aie Mendenhall. > Limestone (Paleozoic) Pda — a a bid 
5 
siderable graphite in the form of carbon known as plumbago or black 
lead. A section through Coyote Mountain is shown in Figure 70. 
Lying on the metamorphic and intrusive rocks is a series of volcanic 
tuffs, agglomerates, and dark lavas which carry interbedded sand- 
stones in Fish Creek Mountain. Upon these lie marine beds with 
corals and oyster reefs, containing many fossils. In Alverson Canyon 
on the south side of Coyote Mountain, red vesicular lava is overlain 
by green and lavender sandstones and conglomerate containing much 
| volcanic matter, in all from 100 to 200 feet thick. Next above are 
tawny sandstones and a thick succession of soft greenish-yellow shale 
co O clay which forms conspicuous badlands in the slopes between 
SS Carrizo Mountain and Fish Creek. Mountain. High-level terrace 
leposits lie across the planed-off edges of the shale. The Tertiary 
Sect their — hae on described by Mendenhall, Kew, 
