Desert Erosion
Aeolian erosion – from the Greek God of wind Aeolus
- Wind erodes arid and semi-arid surfaces and transports particles
- It does this in three ways:
- Deflation: The carrying and removal of loose material by wind
- Abrasion: When wind-blown sand abrades rock surfaces
- Attrition: Loose materials collide with each other and become smaller
Deflation
- Wind removes fine sediments and lowers the desert floor
- This leaves coarser gravels, forming slag-type deposits of duricrust from the exposed bedrock
- This hardened desert floor, known as desert pavement, limits any future deflation and forms the features of a 'reg' desert
- Strong wind eddies can further hollow out the desert surface to form deflation hollows (blowouts)
- These deflation hollows are usually small but can extend several square kilometres
Image showing the formation stages of a desert pavement through deflation
Image showing how deflation hollows form
Abrasion
- Wind laden with sand carves and sculpts rock (sandblasting), usually within a metre of the desert floor
- The strength, duration and direction of the wind will dictate the rate and intensity of the abrasion
- The geology of the rock also factors into the rate of abrasion, with sandstone and limestone being the easiest to erode
Image showing how wind abrades rock in the desert
Attrition
- Attrition in deserts occurs during transportation and small pebbles are picked up by the wind
- These pebbles are too heavy to be carried far and attrition occurs within 0.5m of the desert floor
- As they move, the pebbles collide with each other and bits of rock are broken
- These smaller pieces are then picked up by the wind and moved further along the desert floor colliding into each other and becoming smaller and smaller
- Eventually, these particles become part of the abrasion process
Image showing how desert attrition occurs