Search results
Results from the WOW.Com Content Network
A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation .
Desert landscapes can contain a wide variety of geological features, such as oases, rock outcrops, dunes, and mountains. [5] Dunes are structures formed by wind moving sediments into mounds. Desert dunes are generally classified based on their orientation relative to wind directly.
Desertification is a gradual process of increased soil aridity.Desertification has been defined in the text of the United Nations Convention to Combat Desertification (UNCCD) as "land degradation in arid, semi-arid and dry sub-humid regions resulting from various factors, including climatic variations and human activities."
The rock mantle in desert pavements protects the underlying material from further deflation. Areas of desert pavement form the regs or stony deserts of the Sahara. These are further divided into rocky areas called hamadas and areas of small rocks and gravel called serirs. [7] Desert pavement is extremely common in desert environments. [15]
Desert pavement evolution. Desert pavement surfaces are often coated with desert varnish, a dark brown, sometimes shiny coating that contains clay minerals. In the US a famous example can be found on Newspaper Rock in southeastern Utah. Desert varnish is a thin coating (patina) of clays, iron, and manganese on the surface of sun-baked boulders.
Deserts and xeric (Ancient Greek ξηρός xērós 'dry') shrublands form the largest terrestrial biome, covering 19% of Earth's land surface area. [2] Ecoregions in this habitat type vary greatly in the amount of annual rainfall they receive, usually less than 250 millimetres (10 in) annually except in the margins.
By nature, ergs are very active. Smaller dunes form and migrate along the flanks of the larger dunes and sand ridges. Occasional precipitation fills basins formed by the dunes; as the water evaporates, salt deposits are left behind. Individual dunes in ergs typically have widths, lengths, or both dimensions greater than 500 m (1,600 ft). [2]
The Atacama Desert (Spanish: Desierto de Atacama) is a desert plateau located on the Pacific coast of South America, in the north of Chile.Stretching over a 1,600-kilometre-long (1,000-mile) strip of land west of the Andes Mountains, it covers an area of 105,000 km 2 (41,000 sq mi), [2] which increases to 128,000 km 2 (49,000 sq mi) if the barren lower slopes of the Andes are included.