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Socrative Student  Please go to your app store and download Socrative Student.

 Enter Classroom: ◦ AXQCI0O0

Wind Erosion

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Essential Questions

1.  What are the different sediment types? 2.  How does wind erode silt? How does

wind erode sand? 3.  Describe how waves form. 4.  Explain why understanding wind erosion

important?

Erosion

 Mechanical weathering breaks rocks apart, erosion moves the broken pieces.

 Water  Wind  Ice

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Sediment types

  Sand = larger   Silt= small

 Clay=small…very small

 Dust (silt and clay)= medium

Wind erosion

  Sand is mostly transported by…   Saltation ◦ Moves sediment by a series of jumps and

bounces

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Wind erosion

  Silt is mostly transported by ◦ Deflation: winds blow sediment into air *dust

storms

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Which Climates produce the most deflation? desert is a barren area of land where little precipitation occurs and consequently living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground.

Farmers

 Deflation: ◦ The loss of silt and sand

is a problem because it blows away the best soil for crops. ◦ Causes depressions

where natural plant cover has been removed

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Sand dune formation

  a dune is a hill of sand built by either wind or water flow.

  Formation 1.  Wind blows sand 2.  Wind is slowed by some type of barrier 3.  Accumulation of sand can now occur 4.  More sand is added buries original barrier * Limited by angle of repose 30- 40 degrees

Loess deposits  predominantly silt-sized sediment, which

is formed by the accumulation of wind-blown dust.

  Formation 1.  Wind carries dust and silt 2.  Silt is deposited in thin layers 3.  Thick layers form from this accumulation *Loess often stands in either steep or vertical faces. loess will often stand in banks for many years without slumping. (unlike sand dunes!)

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Wave erosion

Wave formation

usually result from the wind blowing over a vast enough stretch of fluid surface. •  wind or some force causes up and

down motion of water

•  Transfers energy

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Breakers

  Some waves undergo a phenomenon called "breaking". A breaking wave is one whose base can no longer support its top, causing it to collapse.

◦ Wave hits the bottom of the shore or sand bar ◦ Collides with another

wave

Wave size 3 Factors affect wind wave size: 1.  Wind speed: wind must be moving faster

than the wave crest for energy transfer

2.  Wind duration: how long the wind blows

3.  Fetch

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Fetch

 The uninterrupted distance of open water over which the wind blows without significant change in direction.

Partner time

Michigan

Erie

Huron

Superior

Ontario

Wes

terl

ies

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Long shore current

 Waves go at an angle to shoreline

◦ Water moves along shore

◦ Carries sediment with it

Shoreline erosion features

A

B

C

D

E

F

G

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Mass movements  Also known as mass wasting, is the

process by which soil, sand, and rock move downslope largely under the force of gravity.

Triggers ◦  Saturation of water(heavy rain fall) ◦  Spring melts ◦  Earthquakes/tectonics ◦ Wind ◦ Humans

Mass movements   Rockfall/slide: ◦  Sudden movement of rocks, normally in mountain

regions

  Landslide: ◦  Sudden movement of masses of loose rock and

soil, down hill/slope.

 Mudflow: ◦  It is a rapid movement of a large mass of mud

formed from loose dirt and water.

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Mass movements  Lahar: ◦ Volcanic mud flow from ash

  Slump: ◦  Slow moving block of soil moves

Down hill

 Creep: ◦ Very slow movement and very effective of all

mass movements

Mass movements

  Solifluction: ◦  slow downslope movement of water-

saturated sediment due to recurrent freezing and thawing of the ground, affected by gravity.