SEDIMENTARY FEATURES PRODUCED BY EFFLORESCENT SALT CRUSTS, SALINE VALLEY AND DEATH VALLEY, CALIFORNIA

Efflorescent sail crusts composed primarily of halite dominate the saline mudflats of Saline Valley and Death Valley California These crusts form by the complete evaporation of saline groundwaler allhe sediment air interface Efflorescent crusts also form where halite dust is inlroduced by wind then dissolved by rain and reprecipitated as the rainwater is evaporated Wind blown silland clay adhere 10 Ihin hydroscopic water films coating crystals in the efflorescenl crusts and coarser sediment is trapped in surface depressions The sedimenl is left as a lag deposit when the halite dissolves at the base of the crust in Ihe undersalUrated waters below the surface Efflorescenl crust deposits slowly aggrade producing irregular sand and silt lenses in poorly sorted porous mud The sand and sill lenses have distinclive cuspate contacts ragged edges and irregular layering and grain size distributions Efflorescenl crusls growing on sandy sediment dislort Ihe upper surface into polygonal bowl shapes or deform ripples into hump shaped lenses Deposition during flooding over an efflorescent crust commonly produces local areas of solution collapse which are filled with the sediment as it accumulates The Iatler resemble load casts but do nol have associated flame structures Efflorescent crust fabrics similar to those in Saline Valley and Death Valley are documented in the lacustrine Blomidon Formation Fundy basin Nova Scotia Canada and Bigoudine Formation Argana basin Morocco Efflorescent crusts composed of less soluble minerals such as gypsum or borates may leave humpy layers of broken crystals and plates Powdery efflorescence of minerals such as thenardile or thermonatrile generally only disturbs the internal layering of sandy deposits Puffy ground in dry mudflats formed by powdery efflorescence growth in mud cracks produces a distinclive granular fabric