| Desert |
| Deserts have negligible rainfall. Their dry soils are eroded rock, containing very little organic matter. In some areas, bare rock is exposed, in others, great thicknesses of sand have accumulated - the "sand seas" or ergs of the Sahara and Arabia. Hot deserts occur in the tropics. Cold deserts have arisen in temperate latitudes due to their distance from the sea, for instance, the Takla Makan and Gobi and the deserts of the northwest USA. Natural vegetation in desert areas is concentrated along the banks of large rivers, around isolated springs (oases), and where higher ground induces rainfall.
Erg Chech, Algeria
Mhamid, Morocco |
