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Weathering and Erosion
Physical weathering
• Physical or mechanical weathering breaks rock into smaller pieces without altering their chemical composition.
• Ex) wind, water (ice), plants (roots)
• Frost wedging-when water seeps into cracks or joints in rock
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Chemical weathering
• Process by which metallic elements reacts with oxygen (oxidation reaction) therefore causing a change in property
• Oxidation of minerals can cause the mineral to decompose and form new minerals
• Ex) oxidation reaction, Carbon dioxide, water
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Water and chemical weathering
• Minerals react chemically with water
• Leaching-when minerals are transported to lower layers of rock
• Oxidation when water carries dissolved oxygen that reacts with the minerals
(forms iron oxide, rust red)
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Acid precipitation
• Precipitation pH = 5.7 slightly acidic (carbonic acid)
• When fossil fuels are burned, sulfur dioxide and nitrogen oxides are released and may react with water in clouds to form nitric acid, nitrous acid, and sulfuric acid
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Erosion
• A process in which the matereials of the Earth’s surface are loosened, dissolved, or worn away and transported from one place to another by a natural agent, such as wind, water, ice, or gravity
• Preventing ErosionWeathering can not be stopped, but erosion can.
• The following are common ways to prevent erosion.
• Plant vegetation
• Spread Mulch
• Build Retaining WallsBuild
• Terraces
Deposition
• The process by which material is laid down
• There is a direct relationship between the velocity of the water and the size and amount of sediment it can carry.
• Fast moving water-carries a lot of sediment
• Wider water ways flow more slowly
Other Features that shape Earth
• Oceans –waves erode coastline
• Glaciers- erode mountains
• Wind-dust storms (desert) erode landforms