salt pan

The Salar de Uyuni, in Bolivia, the world's largest salt pan. Natural salt flats or salt pans are flat, open expanses of ground covered with salt and other minerals, usually shining white under the sun. They are found in deserts and are natural formations (unlike salt evaporation ponds, which are artificial).

A salt flat forms by evaporation of a water pool, such as a lake or pond. This happens in climates where the rate of water evaporation exceeds the rate of precipitation — that is, in a desert. If the water cannot drain into the ground, it remains on the surface until it evaporates, leaving behind minerals precipitated from the salt ions dissolved in the water. Over thousands of years, the minerals (usually salts) accumulate on the surface. These minerals reflect the sun's rays and often appear as white areas.