playa

A playa; also known as an alkali flat, sabkha, or salt flat; is a dry lakebed, generally the shore of, or a remnant of, an endorheic lake. Such flats consist of fine-grained sediments infused with alkali salts. Their surface is generally very dry, hard and smooth in the summer months, but wet and very soft in the winter months. Playas are small, round depressions in the surface of the ground. A playa lake is formed when rain fills this hole with water, creating a small lake. Playas can also form when the water table intersects the surface and water seeps into them.
_Wikipedia