Wind transportation: can’t carry as much as water.

• Bed Load (within 1 m of ground surface): saltation, rolling, and sliding
• Suspended load: silts and clays

• Abrasion: sand blasting
• Deflation: wind picks up loose surface sediment
• Lowers ground surface
• concentrates rocks too large to be moved by wind (desert pavement).

• sand dunes

Loess: Wind blown silt and clay from deserts and glacial meltwater streams.

Running water causes most erosion. Why?

• Little vegetation to prevent erosion
• most rainfall occurs in brief, intense rainstorms
• more water during glacial ages

Yucca Mountain: being investigated for storage of high level nuclear waste.
 Little rainfall (<6 in/year)
deep water table (>1800 feet)
impermeable rock (volcanic)
Questions: tectonic activity?

Desert locations:
Many deserts are located at 20° to 30° N and S

Reason: Air circulation
Because of earth's curvature, sun's rays are more direct at equators than the poles.
Convection: hot air rises at equator, sinks at poles.

Earth’s rotation breaks up circulation pattern into cells.

As air rises and cools, water condenses.
As air sinks and warms, water evaporates.
At 20º to 30ºN and S, sinking dry air causes deserts.
Deserts also occur at poles.

Other deserts:
continental interior and leeward of mountains (rainshadow)