chapter 19 and chapter 21

chapter 19 and chapter 21 - Grotzinger Jordan Press Siever...

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
Understanding Earth Chapter 19: WINDS AND DESERTS Grotzinger • Jordan • Press • Siever
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Where deserts are located (also remember the polar regions)
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Wind as a fluid • Like water, air flow is described by streamlines affected by velocity, channel depth, and viscosity. • Air has low density and viscosity compared to water – producing turbulent flow • Turbulent air flow is effective in suspending fine-grained sediments, which act as erosion agents when impacting larger material • Deserts are strongly influenced by wind processes because water is minimal or absent, and vegetation sparse
Background image of page 4
Wind as a transport agent • Wind transports particles in the same way water does – The vertical and horizontal currents in turbulent flow lift and carry grains for a distance that depends on particle size • As with water, there is suspended load and bed load, and saltation is an important process. – The low viscosity of air allows the saltating grains to “jump” higher, and when they fall, they strike harder. – Ripples and dunes form – A strong wind can move significant quantities of sand….
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Material carried by wind Wind transports dry loose material -wet sand will not be lifted. Most windblown sand is locally derived and travels only a short distance (exceptions include the Sahara, with transport >1000 km). Windblown dust however can be transported over very long distances, and volcanic dust remains suspended for years, affecting global weather. Typical materials include quartz, feldspar, clay, and carbonates Frosted appearance of wind-blown grains due both to abrasion and chemical dissolution in presence of dew
Background image of page 6
Sands rounded and sorted by wind
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Transported sand is an effective sandblasting agent that removes particles from rock by impact erosion The pebbles that have been faceted by sandblasting are called ventifacts . Sand erosion
Background image of page 8
Image of page 9
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 57

chapter 19 and chapter 21 - Grotzinger Jordan Press Siever...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online