Transcript Wind (aeolian)

Eolian Landforms
Wind
• An agent of erosion
– “eolian” refers to wind
• 2 types of eolian erosion:
– abrasion: sandblasting
• YARDANG
– deflation: blowing away loose particles
• DESERT PAVEMENT
Dust storms and sand storms
• Dust Storm:
– strong winds
– sparsely vegetated
– dust is carried high into air; dark cloud
Dust storms and sand storms
• Sand Storm:
– sand can be carried only 1-2 meters high
– can be heard
– sand moves by SALTATION
DUNE
• Accumulation of sand,
shaped by wind
• Dunes have windward
and leeward slopes
angle of repose
• Angle at which loose material is stable
• 30 – 34 ° for sand
Types of Sand Dunes:
1. Barchan
–
–
–
point downwind
windward slope is gradual
leeward slope is steeper
Types of Sand Dunes:
2. Transverse:
waves of sand
crests are perpendicular to wind
Types of Dunes
3. Barchanoid
ridge of coalesced barchans
Types of Sand Dunes:
4. Parabolic:
point upwind
vegetation anchors arms
large blowout depression in center
Coastal Blowout Dune
– a type of parabolic
– coastal location (Great Lakes)
– point upwind
Hairpin
– type of parabolic
– long and narrow
– point upwind
5. Longitudinal
– parallel to wind direction
6. Star Dunes
– wind from all directions
Loess
• Silt-sized, wind-deposited deposit
• From outwash deposits of Pleistocene
glaciers