by neufer » Sun Nov 25, 2012 4:07 pm
http://en.wikipedia.org/wiki/Oasis wrote:
<<In geography, an oasis (plural: oases) or cienega (Southwestern United States) is an isolated area of vegetation in a desert, typically surrounding a spring or similar water source. The word oasis comes into English via Latin: oasis from Ancient Greek: ὄασις óasis, which in turn is a direct borrowing from Demotic Egyptian. The word for oasis in the later attested Coptic language (the descendant of Demotic Egyptian) is wahe or ouahe which means a 'dwelling place'. 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.
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. People who live in an oasis must manage land and water use carefully; fields must be irrigated to grow plants like dates, figs, olives, and apricots. The most important plant in an oasis is the date palm, which forms the upper layer. These palm trees provide shade for smaller trees like peach trees, which form the middle layer. By growing plants in different layers, the farmers make best use of the soil and water. Many vegetables are also grown and some cereals, such as
wheat, barley and millet, are grown where there is more moisture.>>
[quote=" http://en.wikipedia.org/wiki/Oasis"]
[float=right][img3="[b][color=#0000FF][size=150]_Oasis_ by Jeffrey K. Bedrick[/size][/color][/b]"]http://iasos.com/oasis/Oasis-smaller.jpg[/img3][/float]
<<In geography, an oasis (plural: oases) or cienega (Southwestern United States) is an isolated area of vegetation in a desert, typically surrounding a spring or similar water source. The word oasis comes into English via Latin: oasis from Ancient Greek: ὄασις óasis, which in turn is a direct borrowing from Demotic Egyptian. The word for oasis in the later attested Coptic language (the descendant of Demotic Egyptian) is wahe or ouahe which means a 'dwelling place'. 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.
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. People who live in an oasis must manage land and water use carefully; fields must be irrigated to grow plants like dates, figs, olives, and apricots. The most important plant in an oasis is the date palm, which forms the upper layer. These palm trees provide shade for smaller trees like peach trees, which form the middle layer. By growing plants in different layers, the farmers make best use of the soil and water. Many vegetables are also grown and some cereals, such as [url=http://asterisk.apod.com/viewtopic.php?f=9&t=15349&p=188168&hilit=wheat#p188168]wheat[/url], barley and millet, are grown where there is more moisture.>>[/quote]