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Earth and its Resources

Earth and its Resources. Forces that Shape the Earth Chapter 5, lesson 4. What Is Weathering?. Weathering : the breaking down of rock into smaller pieces by natural process Ice Moving Water Vegetation. Two types of Weathering. 1. PHYSICAL Breaking down of rock by physical movements

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Earth and its Resources

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  1. Earth and its Resources Forces that Shape the Earth Chapter 5, lesson 4

  2. What Is Weathering? • Weathering: the breaking down of rock into smaller pieces by natural process • Ice • Moving Water • Vegetation

  3. Two types of Weathering 1. PHYSICAL • Breaking down of rock by physical movements • Water • Plants • Animals • Frost wedges into cracks and expands • Moving water carries pieces of rock • Plants root under rocks and grow • Animals burrow and bring pieces underground

  4. Two types of Weathering(cont.) 2. CHEMICAL • Breaking down of rock by changes in its chemical composition • Oxygen VS iron • Acids • Rocks contain iron which reacts with oxygen in the air • Oxygen and iron make rust, which makes the rock less strong than it was before • Carbonic acid, or acid rain, can wear away at natural limestone

  5. Erosion and Deposition • Erosion is the picking up and removing of rock pieces • Deposition is the dropping off of particles in another location • Wind contributes to erosion • Carries small particles in the wind • Shapes sand dunes • Water contributes to erosion • Freezing and thawing changes landscape • Melting snow affects soft rocks

  6. Erosion and Deposition (cont.) • Flowing water is a major cause of erosion • When the river slows down, some of the particles are deposited as sediment, or loose pieces of rock • This can cause the river to meander, or curve

  7. How can moving water change the land? • Gravity and glaciers are other agents that cause erosion • Glaciers form when more snow falls than it can melt • When ice sheets are about 100 meters thick, it begins to fall downhill • When it falls, it takes loose pieces of land with it • This mixture of land pulled loose by glaciers is called till • These deposits take the form of a ridge or mound, called a moraine

  8. How is soil formed? • Weathering results in loose rock pieces which become a part of soil • Soil: a mixture of weathered rock, air, water, living things, and humus • Humus: material made of decayed plant and animal remains • Bacteria, fungi, worms, and insects all contribute to the formation • When plants or animals die, their remains enrich the soil and develop layers called soil horizons

  9. Why is soil important? • Minerals in soil cannot be replaced, it must be conserved • Soil can be ruined by….. • Growing too many plants Or the same plants many years in a row • Dumping waste in soil • Paving over land • Building dams

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