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ENV3110 Dryland Environments GY3091 Californian Drylands GY3102 Geomorphology of Desert Environments PowerPoint PPT Presentation


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ENV3110 Dryland Environments GY3091 Californian Drylands GY3102 Geomorphology of Desert Environments. Aeolian Geomorphology. Why are aeolian processes so important in drylands?. Windier? More sediment? Greater sediment availability?. Deflation and Abrasion.

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ENV3110 Dryland Environments GY3091 Californian Drylands GY3102 Geomorphology of Desert Environments

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Env 3110 aeolian geomorphology

ENV3110Dryland EnvironmentsGY3091Californian DrylandsGY3102Geomorphology of Desert Environments

Aeolian Geomorphology

ENV 3110 ~ Aeolian Geomorphology


Why are aeolian processes so important in drylands

Why are aeolian processes so important in drylands?

  • Windier?

  • More sediment?

  • Greater sediment availability?

ENV 3110 ~ Aeolian Geomorphology


Deflation and abrasion

Deflation and Abrasion

  • Deflation: the removal by the wind of loose clastic particles

  • Abrasion: erosion by the wind of cohesive materials as a consequence of bombardment by wind-tranported particles

ENV 3110 ~ Aeolian Geomorphology


Landforms of wind erosion

Landforms of wind erosion

  • Ventifact

  • Yardang

  • Pan

  • Stone pavement

ENV 3110 ~ Aeolian Geomorphology


What are these

What are these?

ENV 3110 ~ Aeolian Geomorphology


Yardang

Yardang

  • A mound composed of generally cohesive sediment whose surface has been abraded (and perhaps deflated) by the wind into an aerodynamic shape

ENV 3110 ~ Aeolian Geomorphology


What is this

What is this?

ENV 3110 ~ Aeolian Geomorphology


Stone pavement

Stone pavement

  • A pebbly covering of a finer soil, which may be formed partly in some circumstances by deflation of finer material

ENV 3110 ~ Aeolian Geomorphology


Stone pavement1

Stone Pavement

ENV 3110 ~ Aeolian Geomorphology


Env 3110 aeolian geomorphology

ENV 3110 ~ Aeolian Geomorphology


Classification of dunes

Classification of dunes

ENV 3110 ~ Aeolian Geomorphology


Fundamental desert sand dune types

Fundamental Desert Sand Dune Types

Dune type Wind Regime Mode of Transport

Transverse

Linear

Star

Unimodal

Bimodal

Complex

Migrating

Extending

Sedentary

ENV 3110 ~ Aeolian Geomorphology


Complete the diagram wasson hyde 1983

Complete the diagram ... (Wasson & Hyde 1983)

ENV 3110 ~ Aeolian Geomorphology


Dust storms and dust haze

Dust storms and dust haze

ENV 3110 ~ Aeolian Geomorphology


Env 3110 aeolian geomorphology

ENV 3110 ~ Aeolian Geomorphology


Why so little work on dust until the 1980s

Why so little work on dust until the 1980s?

  • Erosion of dust often leaves little clear evidence of occurrence.

  • Deposition of dust does not produce distinctive landforms. Often it leaves only thin, widespread mantles.

ENV 3110 ~ Aeolian Geomorphology


Loess

Loess

“A terrestrial windblown silt” (Pye, 1987, p.199)

  • commonly 50-75% quartz;

  • commonly buff colour, but also grey, red, brown, yellow;

ENV 3110 ~ Aeolian Geomorphology


Loess1

Loess

  • typically modal size around 20-40 μm (sand content >20% termed “sandy loess”)

  • Syn- and post-depositional reworking is common;

  • angular and sub-angular grains.

ENV 3110 ~ Aeolian Geomorphology


Smalley krinsley 1978 p 63

Smalley & Krinsley (1978, p. 63)

  • “Glacial grinding is the only natural process which efficiently converts sand-sized quartz particles totally into a silt-sized product.”

ENV 3110 ~ Aeolian Geomorphology


Chinese loess

Chinese loess

ENV 3110 ~ Aeolian Geomorphology


Mapping loess occurrence

Mapping loess occurrence

1984

ENV 3110 ~ Aeolian Geomorphology


Mapping loess occurrence1

Mapping loess occurrence

1988

ENV 3110 ~ Aeolian Geomorphology


Peridesert loess matmata plateau tunisia

Peridesert loess: Matmata Plateau, Tunisia

ENV 3110 ~ Aeolian Geomorphology


Env 3110 aeolian geomorphology

ENV 3110 ~ Aeolian Geomorphology


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