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Look down the valley to the southwest and
you'll see the white, mirage-like surface of Soda Dry Lake. Playa lakes are
among the flattest landforms in the world. They form under arid conditions
when water drains into basins with no outlet to the sea and quickly
evaporates. Soda Lake lies at the terminus of the Mojave River. In wet
years, the playa contains standing water. In drier times, water may lie very
near the surface of the playa. Capillary action draws the water upward where
it evaporates, leaving a white, puffy crust of evaporate minerals such as
sodium carbonate and sodium bicarbonate.
During wetter climates, the playa lake basins
of the Basin-and-Range province were filled with perennial lakes. At least
twice, from 18,000 to 16,000 years ago and from 13,700 to 11,400 years ago,
a long-lived lake, Lake Mojave, filled Soda and Silver Lake playas. Lake
Mojave dried out by 8,700 years ago, becoming the playa we see today.
Soda Lake gets its name from the soda deposits
found on its surface. Soda, in actuality, is a combination of various
salts/ions (I.e. sodium, calcium, potassium, chloride, and carbonate) that
are beneficial to humans. About 100 years ago, people began various attempts
at extracting the salts from the lake bed. A fresh water spring, located at
ZZYZX mineral springs, was used as the water source for these various
undertakings.
Playas
A playa is a dry, vegetation-free, flat area at the lowest part of an
undrained desert basin. It is a location where ephemeral lakes form during
wet periods, and is underlain by stratified clay, silt, and sand, and
commonly, soluble salts. Playas occur in intermountain basins throughout the
arid southwestern United States. Although playas may appear as featureless
plains, they are rich in features and characteristics that can reveal
information about climates, past and present. Many playas in the Mojave
region were the location of lakes and marshes during the last glacial
period. These perennial water bodies completely dried up about 8,000 years
ago. Today they flood only after seasonal storms provide flashflood waters,
or in some cases, springs discharge large quantities of groundwater onto the
playa.
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| Winter storm precipitation results in increased water
discharge onto Soda Lake from one of several springs near Zzyzx, CA
(photo by Dave Bedford, February, 2001). |
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