sabkhah, (Arabic), saline flat or salt-crusted depression, commonly found along the coasts of North Africa and Saudi Arabia. Sabkhahs are generally bordered by sand dunes and have soft, poorly cemented but impermeable floors, due to periodic flooding and evaporation. Concentration of seawater and capillary discharge of groundwater result in deposits of gypsum, calcite, and aragonite. Most sabkhahs are thought to have once been small sea inlets and are akin to basins in which evaporites formed in the geological past.