ABSTRACT
Evaporite deposits form in seas, lagoons, and internally drained lakes, where more water leaves the basin by evaporation than enters as rainfall, surface, and subsurface flow. Evaporite rocks are inorganic in origin and form by chemical precipitation in a concentrated solution. The most common evaporite rocks include gypsum, anhydrite, and halite, although other rarer salts can be significant locally in karst. Carbonates such as calcite and dolomite can also be of evaporitic origin; however, the term “evaporite karst” is normally employed to denote karst in the above-mentioned more soluble salts, most commonly in gypsum and halite. Under normal conditions, the solubility of gypsum is up to three orders of magnitude greater than that of calcite, but the solubility of salt is roughly 140 times greater than the solubility of gypsum. Where they are in contact with undersaturated water, evaporite rocks may dissolve at very high rates (see Dissolution: Evaporite Rocks).
