1. Desert Erosion and Landform Development

2. How do you think this formed?

3. What are the main agents of erosion in deserts?
Wind
Water
Contrary to what we might believe, water is actually thought to be the most significant agent of erosion at work in desert environments

4. Weathering
What is the difference between chemical and physical weathering? Write a definition for each.
Which is most important in a desert? (see p 290 PG)
Why is weathering in deserts so slow?

5. Insolation Weathering

6. Insolation weathering
Also known as exfoliation or onion skin weathering. Why?
Large diurnal temp range (alternate heating & cooling)
Occurs when there is a sudden temperature change (eg cool rainfall)
In deserts rock temperatures of up to 80 degrees have been recorded. Rocks may be 20 degrees hotter than the surrounding air.

7. Salt Crystallisation
Most efficient underground, where there is more moisture
Salt crystallisation is where rocks are broken down by salt crystals growing in the cracks
Salts in the soil and rock are dissolved and penetrate porous rocks eg sandstone
As they recrystallise they exert pressure and force the rocks to break apart

8. Sand Blasting
Entrained particles (those picked up by the wind) are carried by the wind, and act like sandpaper on the bottom of rocks where most sand particles are carried. (abrasion)
Helps to form mushroom rocks (but chemical weathering is important too)

9. Solution weathering
A form of chemical weathering, where rainwater dissolves soluble particles in the rock.

10. Relic Features
Many desert features are actually relic features from times when there was much more water present in the environment.

15. What is badland topography?
See p 292 PG

17. What is the impact of the slow rate of weathering in arid environments on the development of landforms?
What is the difference between weathering and erosion?
How does the rate of weathering affect desert erosion?

18. Desert Landforms
Weathering and erosion combine to form some significant desert landforms.
Water and wind both play an important role in their formation

19. Water and landform development in arid environments
Make notes from p on:
The role of water
Rainsplash
Exotic rivers
Internal drainage
Playas
Evaporites
Wadis/arroyos/dry creeks
Alluvial fan
Piedmont
Bajada
Box canyon
Anabranches
Reticulate drainage
Inselbergs (see p 192 landform systems)

20. Why is water more effective than wind at shaping landforms in arid environments?

21. Wind and landform development in arid environments.
Make notes from p on
Aeolian action
Ergs
Deflation & deflation hollows
Saltation
Sand sheets
Barchans
Parabolic dunes
Longitudinal or seif dunes
lunettes

22. Pics from