Sand Forms in the Coachella Valley, Southern California

The Coachella Valley, in Southern California, is a northern section of the Salton Basin which is partially covered by alluvial deposits and, in a few localities, is mantled by sand deposits. The sand deposits cover a considerable area, but they form relatively unimpressive landform features, being transitory elements subject to natural obliteration or cultural extinction. The sources of sand lie in the alluvial materials deposited in the northern end of the valley. These deposits are subject to northwest winds, including air movements flowing through San Gorgonio Pass. The prevailing winds sift out the finer materials and move them southward, creating several kinds of sand forms in the course of transport. Knob dunes, elongated low mounds formed in the lee of desert shrubs, are the most frequent form, ranging up to six feet high and thirty-five feet long. Knob dunes may occur in large dune fields. Wave dunes, barchan-like in form, are the largest of the sand forms, ranging up to thirty feet in height and a hundred feet long. Mesquite-hill dunes are small forms which collect around patches of mesquite, forming dune fields of changing shape and form as the plant group increases or dies out. Other sand forms, such as sand drifts, sand undulations, and sand veneers exhibit few distinctive or finite forms but are different systems of covering country rock with thin to thick accumulations of transient sand. These formless sand covers occur in particular localities having special conditions of air flow, in which air movements seem to lack the strength capable of creating distinctive sand forms. Some sand undulations occur in localities lacking distinctive plant covers capable of initiating particular sand forms. Particularly sand veneers may be found marginal to fields of knob and mesquite-hill dunes. Although the present conditions of sand transport are affected by cultural interference, there is a sequential aspect to the development of sand forms, in which the sand veneer thickens into a field of knob dunes, may become a moving field of undulating form, ending in the barchanlike form in terminal downwind locations. Mesquite-hill dune fields may be relatively permanent forms. Sand drifts and sand veneers often appear to be localized accumulations which periodically are dissected by storm drainage, providing redistribution of sands to other locations, from which air flow then transports the finer sands and creates the knob dune fields

Aeolian processes · Alluvial fan · Alluvium · Archaeology · Geography · Geomorphology · Landform · Sand dune stabilization · Structural basin · Aeolian processes and effects · Botany, Ecology, and Taxonomy Studies · Geological formations and processes · Geology · Paleontology

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