How do you think this formed? What are the main agents of erosion in deserts? Wind Water Contrary to what we might believe, water is actually thought.

Desert Erosion and Landform Development

How do you think this formed?

What are the main agents of erosion in deserts?WindWater

Contrary to what we might believe, water is actually thought to be the most significant agent of erosion at work in desert environments

WeatheringWhat 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?

Insolation Weathering

Insolation weatheringAlso 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.

Salt CrystallisationMost efficient underground, where there is

more moistureSalt crystallisation is where rocks are broken

down by salt crystals growing in the cracksSalts in the soil and rock are dissolved and

penetrate porous rocks eg sandstoneAs they recrystallise they exert pressure and

force the rocks to break apart

Sand BlastingEntrained 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)

Solution weatheringA form of chemical weathering, where

rainwater dissolves soluble particles in the rock.

Relic FeaturesMany desert features are actually relic

features from times when there was much more water present in the environment.

What is badland topography?

See p 292 PG

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?

Desert LandformsWeathering and erosion combine to form

some significant desert landforms.Water and wind both play an important role

in their formation

Water and landform development in arid environmentsMake notes from p292-294 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)

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

Wind and landform development in arid environments.Make notes from p295-296 onAeolian actionErgsDeflation & deflation hollowsSaltationSand sheetsBarchansParabolic dunesLongitudinal or seif duneslunettes

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