Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown...
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Transcript of Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown...
![Page 1: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/1.jpg)
Weathering, Erosion, and Soils
![Page 2: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/2.jpg)
What is weathering?
• Weathering is the physical or chemical breakdown of rock into smaller pieces
• Two types of weathering:– Mechanical– Chemical
![Page 3: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/3.jpg)
Mechanical Weathering
• Physical breakdown of rock into smaller pieces
• Only SIZE changes, not composition• Examples…
– Frost wedging:water freezes, expands,breaks rock apart
![Page 4: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/4.jpg)
Mechanical Weathering
• Physical breakdown of rock into smaller pieces
• Only SIZE changes, not composition• Examples…
– Exfoliation: removal of pressure causes it to expand and crack; layer wearsaway
![Page 5: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/5.jpg)
Mechanical Weathering
• Physical breakdown of rock into smaller pieces
• Only SIZE changes, not composition• Examples…
– Root wedging: plant roots actlike ice to split rock
![Page 6: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/6.jpg)
Chemical Weathering• Chemical reactions break the
minerals/rocks into different materials
• Composition changes• Examples…
– Oxidation: mineral reacts with oxygen and break off (e.g., iron turns to rust)
![Page 7: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/7.jpg)
Chemical Weathering
• Chemical reactions break the minerals/rocks into different materials
• Composition changes• Examples…
– Hydrolysis: chemicals in rock react with water,causing some minerals to break away
![Page 8: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/8.jpg)
Chemical Weathering
• Chemical reactions break the minerals/rocks into different materials
• Composition changes• Examples…
– Carbonation: CO2 and water make carbonic acid that washes away some minerals (especially limestone)
![Page 9: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/9.jpg)
Chemical Weathering
• Chemical reactions break the minerals/rocks into different materials
• Composition changes• Examples…
– Acids (in living things or due to pollution) can crack rock
![Page 10: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/10.jpg)
What is Erosion?
• Erosion is the movement of weathered materials from one location to another (often downhill)
• Caused by:– Wind– Gravity– Running water– Glaciers– Plants, animals, people
![Page 11: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/11.jpg)
Weathering vs. erosion
• Weathering breaks down rocks, which ultimately makes soil
• Erosion carries it away!
![Page 12: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/12.jpg)
Wind erosion
![Page 13: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/13.jpg)
Gravity erosion
![Page 14: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/14.jpg)
Running water erosion
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Glacial erosion
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Plant, animal, human erosion
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What is soil?
• Soil is a mixture of weathered rock, organic matter (living/decaying), air, and water
• Made from…– Materials weathered from bedrock
(underlying “parent” rock),– Materials deposited from erosion– Organic matter made by the actions of
living things
![Page 18: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/18.jpg)
Soil types
• Type of soil mainly depends on the parent material (bedrock)– Example: quartz-rick rocks produce sandy
soil– Example: iron-rich rocks produce red soil
• Also depends on climate (temperature and rainfall)– Determines amount of organic matter
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Soil textures
• Particle size– Sand– Silt– Clay
• If particles are too small, soil can’t hold much air and water
• If particles are too large, water runs right through!
![Page 20: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/20.jpg)
Soil fertility
• How well a soil can support plant growth
• Factors include minerals/nutrients, organisms living in soil, precipitation, topography, acidity
![Page 21: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/21.jpg)
Soil profiles
• Soil profiles are the vertical sequence of layers– The layers are called
horizons
• Soils in different areas produce different profiles
• Climate affects the horizons
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Soil erosion
• Soil erosion is the movement of soil from one place to another– Caused by wind,
water, glaciers, animals/plants, human activity
• Weathering creates soil, erosion destroys it!
![Page 23: Weathering, Erosion, and Soils. What is weathering? Weathering is the physical or chemical breakdown of rock into smaller pieces Two types of weathering:](https://reader033.fdocuments.net/reader033/viewer/2022061612/56649eaa5503460f94baefb3/html5/thumbnails/23.jpg)
Human causes of soil erosion
• Development for housing/buildings
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Human causes of soil erosion
• Development for housing/buildings• Deforestation• Farming• Widespread and devastating problem
around the world– “Desertification”– Dust Bowl of the 1930s
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Dust Bowl, 1930s
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Destitute Pea Pickers in California. Mother of Seven Children. by Dorothea Lange
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How can we prevent it?
• Plant trees and groundcover
• Improve farming practices– Contour plowing– Strip cropping– Terracing– Crop rotation– Cover cropping
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Your summary
• 2-3 sentences summarizing these notes