In geography, an oasis (plural: oases or
oasi) or cienega (Southwestern United States) is an isolated area of vegetation in a desert, typically surrounding a spring or similar
water source. Oases also provide habitat for animals and even humans if the
area is big enough. The location of oases has been of critical importance for
trade and transportation routes in desert areas. Caravans must travel via oases
so that supplies of water and food can be replenished. Thus, political or
military control of an oasis has in many cases meant control of trade on a
particular route. For example, the oases of Awjila, Ghadames and Kufra, situated in modern-day Libya, have at various times been vital to both
North-South and East-West trade
in the Sahara.
Oases are
formed from underground rivers or aquifers such as an artesian aquifer, where water can reach the surface naturally by pressure or
by man made wells. Occasional brief thunderstorms provide subterranean water to
sustain natural oases, such as the Tuat. Substrata of impermeable rock and stone can trap
water and retain it in pockets; or on long faulting subsurface ridges or
volcanic dikes water can collect and percolate to the surface. Any incidence of
water is then used by migrating birds who also pass seeds with their droppings
which will grow at the water's edge forming an oasis.
An oasis in the Negev Desert of Israelcreated by trees planted by the Jewish National Fund.
The Huacachina oasis in Ica, Peru
Source:Wiki/Oasis
