mhmoudkhlifa
مشرف وجيومتميز
العمر : 19
سجّل في : 01 ماي 2007
عدد المساهمات : 681
university : HELWAN
 |  موضوع: Sand Dunes - Land-Locked  2007-10-11, 1:35 am | |
| Sand Dunes - Land-Locked
Sand dunes form wherever environmental conditions provide sand, steady wind and a location for the sand to collect. This may occur in both coastal and terrestrial settings.
Land-Locked Dunes
Sand starts as bedrock, which is broken down into blocks, a size at which water is able to transport them downstream. Eventually these large blocks may be jostled around enough to be broken into sand-sized grains. Sand and other sediment usually ends up deposited along the sides of streams, in lakes, or in the ocean, but what happens when it doesn't? An ephemeral, or seasonal stream, during its dry periods, is exposed to wind. Occassionally a lake will dry up, with its sediment left without the protection of water. These two sources feed land-locked dune fields.
There are many examples of terrestrial dune fields within the National Park Service system. Listed below are Parks containing land-locked dunes. Click here to learn more about dune formation and coastal systems.
Terrestrial Dunes
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