Download - Natural arch
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Natural arch
• Typically formed by a combination of wind and water
• Narrow ridges are formed and the softer substrata is weathered first, forming a bridge/arch overhead
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Ventifact
• Created by wind erosion• Wind carries fine particles that work like a
sand blaster (i.e. sand, silt, clay, and ice particles)
• The windward face of the rock is flattened and smoothed
• Usually pebble to cobble sized
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• A type of ventifact that has three ridges• Multiple faces have been formed by either
a changing prevailing wind or movement of the actual rock being weathered
Dreikanter
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Desert pavement
• Formed in arid environments when wind carries finer, more lightweight particles such as sand away
• Large particles are left behind and protect from further erosion
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Loess
• Yellowish, fine grained silt and clay sized particles
• Formed by glaciers• Carried and deposited by wind
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leeward leewardwindward
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Sand Dunes
• Piles of sand• Deposited by wind• Leeward side (slipface) has a steeper
slope• Windward side is more gradual
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Barchan Dune
• Crescent shaped dunes• Concave side is the leeward side• Formed from a unidirectional wind
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Transverse dunes
• A dune that elongates perpendicular to the prevailing wind
• Caused by a combination of wind directions
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Parabolic dunes
• Crescent shaped dunes• Concave side is the windward side• Found in coastal deserts• Arms of the crescent lag behind because
they are held in place by vegetation
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Ergs
• Huge dune fields• Notice the source of sand from the photos
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Ripple marks
• Miniature dunes within a dune (not more than 2 inches tall)
• Formed by wind• May form from cross winds and appear to
be traveling in a different direction than the large dune
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Deflation
• Low spots carved out by wind erosion• High elevations are left due to vegetative
stabilization
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Pedestal rock
• Base of a rock is weathered and eroded more quickly due to sand blasting
• Sand grains can only be picked up a couple of feet