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Chapter 8

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A process that wears away surface materials and moves them from one location to another Causes of erosion: a. Gravity b. Water c. Wind d. Glaciers

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Deposition- the dropping of sediments that have been eroded or weathered away This is the final step in the erosion process.

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Mass movement when gravity alone moves materials down slope Four types: a. Slump b. Creep c. Rockslides d. Mudflows

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Mass movement that happens when loose materials or rock layers slip down a slope

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Gets name from way sediments inch down a hill Look for slopes where trees, poles or fences lean downhill The entire hill moves downward slowly (like an inch per year)

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Large blocks of rock break loose from steep slope, start falling, crash into more rocks, knock them loose, etc. Often occur in winter because of freezing & thawing in cracks causing fractures

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Thick mix of sediments and water flowing down a slope

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creep clip creep clip Rockslide in Tennessee Rockslide in Tennessee Mudslide in Italy Mudslide in Italy

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Runoff Stream and River Ocean Shoreline Groundwater

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Water that doesnt soak into the ground or evaporate; it flows across the Earths surface Can create rills, gullies, or sheets Rills GullySheet

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Results of water erosion: Combined

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Water flows along a channel Water picks up light sediments and moves them Large, heavy things just roll along the bottom of the channel Heavy things scrape and bump against bottom and sides of channel Stream continues to cut a deeper and wider channel

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Alluvial fan: shaped like a triangle Delta: sediments not deposited until river enters ocean, gulf, or lake Alluvial fan Delta

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Waves move sediments back and forth, eroding and re-depositing sediment Beaches are a result of sand being deposited Waves can also erode rocky cliffs to make caves

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Water that soaks into the ground and fills holes in rocks below the surface Can create wells, springs, and geysers

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Water mixes with carbon dioxide to form a weak acid Limestone is easily dissolved by acid, so as acidic groundwater moves through cracks, the cracks are enlarged until a cave is formed

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Air movement picks up loose materials and transports them Deflation: wind removes small particles such as clay, silt, and sand, leaving behind coarse materials Abrasion: when windblown sediments strike and erode rocks Wind erosion usually happens in deserts, beaches, and plowed fields

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A mound of sand drifted by the wind Windward side has a gentle slope Leeward side has a steeper slope

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Windbreaks: People plant vegetation to reduce wind erosion and trap snow moisture Grasses make good root systems on steep slopes and on the coastline

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Moving mass of ice and snow is a glacier Snow piles up, compressing the ice on bottom Ice partially melts & becomes putty-like Whole mass begins to slide on putty layer and moves downhill

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Plucking: ice cracks rocks, pieces are lifted up by the glacier Grooves: rocks scrape the dirt under the glacier leaving long parallel grooves Striations: smaller scrapes than grooves Cirque: bowl-shaped hole left by glacier Arete: ridge formed when two glaciers erode mountain from different directions Horn: sharp peak left by multiple glaciers eroding mountain

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Till: mix of sediment left at glacier base Moraine: ridge of sediment left in front of the glacier when it stops pushing forward Outwash: sediment deposited by melted water from the glacier Kettle: lake left behind by the glacier

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