II. DESERT SOILS
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areas of gypsum sand dunes, such as those found near White Sands, New
Mexico, the Great Salt Lake Desert, Utah, along the Pecos River, Texas,
and as crusts in the Tunisia and other deserts. Deposition in confined
desert valleys or playas may follow a definite order of solubility pattern.
For example, in salt pans, chlorides are in the center of the pan or at
the places on the surface where the ground water evaporates, sulfates surround the chloride accumulations and carbonates surround the sulfates and
underlie them.
Gypsum, like any other salt, moves upward in solution by capillary action from gypsiferous deposits through unconsolidated materials and soils,
evaporates, and accumulates as crystals on the soil surface. Gypsum may
characteristically precipitate in root channels giving the soil the whiteveined appearance seen in Fig. 12. Wind action drifts the gypsum sand
crystals formed into dunes and the process continues, producing more crystals and more drifting gypsum sand. Marine sources of sand gypsum have
been ruled out.
With certain slight changes in climate, gypsum may become covered
with wind-deposited soil particles, forming a layer of loess. Soils formed
Fig. 12. Veinings of gypsum, deposited in soil root and worm channels. Commonly
found under irrigated conditions where gypsum is a common salt constituent of
the virgin soil.
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areas of gypsum sand dunes, such as those found near White Sands, New
Mexico, the Great Salt Lake Desert, Utah, along the Pecos River, Texas,
and as crusts in the Tunisia and other deserts. Deposition in confined
desert valleys or playas may follow a definite order of solubility pattern.
For example, in salt pans, chlorides are in the center of the pan or at
the places on the surface where the ground water evaporates, sulfates surround the chloride accumulations and carbonates surround the sulfates and
underlie them.
Gypsum, like any other salt, moves upward in solution by capillary action from gypsiferous deposits through unconsolidated materials and soils,
evaporates, and accumulates as crystals on the soil surface. Gypsum may
characteristically precipitate in root channels giving the soil the whiteveined appearance seen in Fig. 12. Wind action drifts the gypsum sand
crystals formed into dunes and the process continues, producing more crystals and more drifting gypsum sand. Marine sources of sand gypsum have
been ruled out.
With certain slight changes in climate, gypsum may become covered
with wind-deposited soil particles, forming a layer of loess. Soils formed
Fig. 12. Veinings of gypsum, deposited in soil root and worm channels. Commonly
found under irrigated conditions where gypsum is a common salt constituent of
the virgin soil.