Desert lakes always contain water, but lose huge amounts of their water through evaporation. These lakes are very salty because salts do not evaporate, and this causes very few organisms to survive. Springs form when the land surfaces come in contact with the underground water supply. This creates wet areas called oases , and these occur when underground rock is just below the surface. Any water in the sand collects, and creates small patches of ground-vegetation , or creates a farm for a small population.
Dunes are landforms on the desert that are shaped by the winds.
Transverse dunes are formed by a steady gentle breeze, and look like ripples of sand on a beach. Stronger winds create barchans , whose edges always point downward. Seif dunes are formed from winds that come from one direction and intersect crosswinds. These dunes are high and extend hundreds of miles. Star dunes are produced by variable winds and form in the shape of stars.