Deserts
Deserts where vegetation cover is exceedingly sparse correspond to the 'hyperarid' regions of the earth, where rainfall is exceedingly rare and infrequent.
Desert landscapes have certain distinctive features. Deserts are often composed of sand and rocky surfaces. Sand dunes called ergs and stony surfaces called hamada surfaces compose a minority of desert surfaces. Exposures of rocky terrain are typical, and reflect minimal soil development and sparseness of vegetation.
Sand covers only about 20 percent of Earth's deserts. Most of the sand is in sand sheets and sand seas—vast regions of undulating dunes resembling ocean waves "frozen" in an instant of time. In general, there are six forms of deserts.
Deserts have a reputation for supporting very little life, but in reality deserts often have high biodiversity, including animals that remain hidden during daylight hours to control body temperature or to limit moisture needs.
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Deserts