Wind and Aeolian Landforms

What is the Coriolis Effect?

The development of wind due to atmospheric circulation caused by differential solar radiation and the Earth’s rotation

Factors controlling wind blown particles

• Wind strength

• Particle size

• Surface Material

How far do the different particle sizes travel?

• Clay sizes - Remain suspended as dust

• Silt Sizes - Transported long distances by suspension, eventually settles out

• Sand Sizes - Transported short distances by saltation

• Gravel Sizes - Not transported

Sediments should be _____ and _____ loose to be easily eroded by wind

Sediments should be dry and loose to be easily eroded by wind

Different types of Aeolian landforms

• Dunes (sand)

• Loess (silt)

Factors controlling dune formation

• Climate

• Location

• Sand supply

Where is sand eroded?

Windward slope

Where is sand deposited?

Lee slope (slip face)

What is this image an example of?

Cross bedding

Different types of dunes

• Parabolic

• Longitudinal

• Barchan

• Transverse

What are the factors controlling dune types?

• Wind

• Sand supply

• Vegetation

Describe a parabolic dune

• Horns point upwind

• Moderate winds; consistent direction

• Moderate supply of sand

• Presence of vegetation; stabilizes horns

Describe a longitudinal dune

• Long ridge of sand running parallel to wind direction

• limited supply of sand

• Little to no vegetation

• Persistent cross winds

Describe a barchan dune

• Horns point downwind

• Limited supply of sand

• Absence of vegetation

• Persistent winds; consistent direction

Describe a transverse dune

• Ridge of sand running perpendicular to wind direction

• Abundant supply of sand

• Absence of vegetation

• Moderate to persistent winds; relatively consistent direction

What is a loess?

Wind blown blanket deposit of silt (and dust)

How is silt eroded and transported?

By suspension

How thick are loess’?

Typically, 30 to 100 metres thick

What is sandblasting?

Bombardment of sand grains eroded by the wind

How can we identify sandblasting on a rock?

Identified by frosted grains

Term used for sandblasted rock?

Ventifact

What is a blowout?

Strong winds erode sand, due to disturbed vegetation, resulting in a hollow.

• potential reactivation of stabilized dune

What is deflation?

Strong winds erode and remove sand and silt resulting in a gravel covered surface

Different types of deflation

• Deflation plateau

• Deflation pavements