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Erosion and Deposition

Erosion and Deposition. Agents, Forces, and Results. What Caused This?. http://commons.wikimedia.org/wiki/File:Water_erosion_below_Hay_Bluff_-_geograph.org.uk_-_1074175.jpg. http://commons.wikimedia.org/wiki/File:Wind_erosion_Seminole_Canyon.JPG.

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Erosion and Deposition

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  1. Erosionand Deposition Agents, Forces, and Results

  2. What Caused This? http://commons.wikimedia.org/wiki/File:Water_erosion_below_Hay_Bluff_-_geograph.org.uk_-_1074175.jpg http://commons.wikimedia.org/wiki/File:Wind_erosion_Seminole_Canyon.JPG http://commons.wikimedia.org/wiki/File:Baventian_Clay_Beds_-_geograph.org.uk_-_1776748.jpg

  3. Erosion–moving of rock material from one place to a new location • Three processes must take place: • detachment of particles • lifting them • transporting them • Agents of erosion: • flowing water • moving ice • waves • gravity • wind • Sand consists of small pieces of rock that have been: • weathered from a parent rock • eroded • deposited somewhere else What is Erosion?

  4. Wind–responsible for wearing away rocks and creating great deserts like the Sahara Desert and Gobi • Most effective in moving loose material • Main effects: • Wind causes small particles to be lifted and moved away. • Suspended particles may impact on solid objects causing erosion by abrasion (rubbing). • Occurs in areas where there is not enough rainfall to support vegetation What Is Wind Erosion? http://commons.wikimedia.org/wiki/File:Wind_Erosion_Features_in_Wadi_Al-Hitan.jpg

  5. Water–most influential force in erosion • Moves materials • Transports large objects with fast moving streams • Wears away rocks: • rivers • lakes • oceans What Is Water Erosion? http://commons.wikimedia.org/wiki/File:Water_erosion_below_Scarsoch_Bheag_-_geograph.org.uk_-_1367808.jpg

  6. Waves–relentless pounding • Erodes: • softer/weaker rock first • harder/more resistant left behind • Can take over 100 years to erode a rock to sand • Energy of waves and chemical content of the water erodes the rock off the coastline. What Is Wave Erosion? http://commons.wikimedia.org/wiki/File:Wave_Erosion,_Downpatrick_Head_-_geograph.org.uk_-_369272.jpg

  7. Mass movement–downward movement of rock and sediments, mainly due to the force of gravity • Streams and glaciers • move material from higher  to lower  elevation • Occurs continuously on all slopes • slow moving and sudden movement until equilibrium is reached What Is Gravitational Erosion? http://commons.wikimedia.org/wiki/File:Purbeck_,_Old_Harry_-_geograph.org.uk_-_1711962.jpg

  8. Ice–moves and carries rocks, grinding the rocks beneath the glacier • Plucking occurs when water enters cracks under the glacier. • freezing • breaking off pieces of rock that are then carried by the glacier • Abrade (abrasion) • cuts into the rock under the glacier • smoothing • polishing the rock surface What Is Glacial Erosion? http://commons.wikimedia.org/wiki/File:U-shaped_valley_at_the_head_of_Leh_valley,_Ladakh_(2).JPG

  9. Deposition– laying down of sediment that has been transported by a medium such as wind, water, or ice • Process of erosion stops: • when the moving particles fall out of the transporting medium and settle on a surface • Speed of the medium slows or the resistance of the particles increases, the balance changes and causes deposition • Speed can be reduced by large rocks, hills, vegetation, etc. What is Deposition?

  10. Wind speed can be related to variations in heating and cooling. • Transportation of particles in wind: • Fine particles in suspension hundreds of km from its original source in the desert • Heavier material may be blown along the ground. • Material is deposited when the wind changes direction or loses its strength. Deposition - Wind http://commons.wikimedia.org/wiki/File:Desert_Chihuahuan_Big_Bend.JPG

  11. Running water enters a large, fairly still body of water and its speed decreases. • SPEED • As the speed of the water decreases, the water's ability to carry sediment also decreases. • Deposited in streams, rivers, and oceans: • Running water deposits sediments where the slowing water can no longer move them. • Largest particles are deposited near the shore. • Increasingly smaller particles settle out farther from the shore where the water is calmer. Deposition - Water http://commons.wikimedia.org/wiki/File:Enchanted_Rock,_stream.jpg

  12. Glacial flows of ice–become slower when the ice begins melting – Deposits left by glaciers: • The deposits of these rivers look similar to normal river deposits and are called outwashes. • Moraines are large chunks of broken rock left at the base and sides of the glacier as it melts and recedes. • Finer material is carried in the rivers that form when the glacial ice melts. Deposition - Ice http://commons.wikimedia.org/wiki/File:Cavell_Glacier_with_Crevices_and_Annual_Rings.jpg

  13. WEATHERING– Think of weather wearing rock down. • EROSION– Think of a road and traveling. • DEPOSITION – Think of depositing money into a bank. What’s the Difference?

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