AMARGOSA DESERT. 159 
important group of sand dunes, 3 miles south of Rose's Well, is shown 
on the map. The Amargosa mine at Rhyolite lias been sunk 330 feet 
in Recent gravel, and in some portions of the valley the Recent allu- 
vial deposits are probably 500 or more feet deep. Inliers of Tertiary 
and Paleozoic rocks are, however, common. Many hills and ridges of 
Paleozoic limestone protrude from the gravel in the southeast corner 
of the area. The line of Paleozoic inliers northwest of the sand dunes 
is probably the crest of a ridge formerly connected with the Amar- 
gosa Range, but now separated from it by a mantle of detrital 
material. 
The springs at Ash Meadows have already been described (p. 20). 
Water has been obtained at the following depths in three wells in the 
valley: Rose's Well, 208 feet; Miller Well No. 1, 183 feet; Miller 
Well No. 2, 70 feet. The water in all cases is good, although that of 
Rose's Well has a slight saline taste. The log of Miller Well No. 1, as 
reported by Mr. W. F. Miller, is as f ollow T s : 
Log of Miller Well No. 1, Amargosa Desert. 
Feet. 
Gravel 2 
"Cement," indurated gravels To 
Gravel 4-0 
" Cement " 10-12 
Sand 0-7 
" Cement " IS 
Gravel (water stratum) 11 
Playa and alluvial slope deposits of the older alluvium outcrop in a 
number of places in the Amargosa Desert, and these beds probably 
underlie at no great distance the south end of the valley. The hills 
in the desert 8 miles south of Bullfrog are composed of angular and 
subangular bowlders and sand derived from the surrounding hills. 
and among other rocks basalt occurs. The material closely resembles 
that of the present alluvial slopes. It has been eroded into hills, and 
its bowlders are somewhat weathered. It is without doubt an alluvial 
slope contemporaneous with the playa deposits next described. South 
of Rose's Well exposures of ancient playa deposits are common, and 
the northern border of the old playa appears to have been north of 
this well. At the southern border of the area surveyed this playa 
was probably 20 miles wide. The deposits now occur as low, white 
domes and dissected mesas, which are particularly abundant south- 
east and east of Miller Well No. 2. Six miles west of the Big Dune 
the deposits consist of fine-grained clay, in which are embedded many 
grotesque lime-carbonate concretions. Bedding planes are rare, but 
appear to be horizontal. The small deposit 1 mile north of Rose's 
Well is similar except that a few small, well-rounded pebbles occur 
in the clay and that a 1-foot layer of white porous limestone is inter- 
