In Arid Climates
Alluvial fans are often found in desert areas subject to periodic flash floods from nearby thunderstorms in local hills. The typical watercourse in an arid climate has a large, funnel-shaped basin at the top, leading to a narrow defile, which opens out into an alluvial fan at the bottom. Multiple braided streams are usually present and active during water flows.
Phreatophytes are plants that are often concentrated at the base of alluvial fans. They have long tap roots 30 to 50 feet (9.1 to 15 m) to reach water that has seeped through the fan and hit an impermeable layer, sometimes collecting in springs and seeps. These stands of shrubs cling to the soil at their bases and often form islands of habitat for many animals as the wind blows the sand around the bushes away.
Alluvial fans are also found on Mars, descending from some crater rims over their flatter floors. Observations of fans in Gale crater made by satellites from orbit have now been confirmed by the discovery of fluvial sediments by the Curiosity rover.
Read more about this topic: Alluvial Fan
Famous quotes containing the words arid and/or climates:
“Language is like soil. However rich, it is subject to erosion, and its fertility is constantly threatened by uses that exhaust its vitality. It needs constant re-invigoration if it is not to become arid and sterile.”
—Elizabeth Drew (1887–1965)
“All climates agree with brave Chanticleer. He is more indigenous even than the natives. His health is ever good, his lungs are sound, his spirits never flag.”
—Henry David Thoreau (1817–1862)