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Weathering and Erosion

Weathering and Erosion. Weathering. Alteration of rock materials during exposure to air, moisture, and organic matter. Responsible for limited changes in the Earth’s surface Soften bedrock Two Types of Weathering Chemical Weathering Physical Weathering. Physical Weathering.

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Weathering and Erosion

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  1. Weathering and Erosion

  2. Weathering • Alteration of rock materials during exposure to air, moisture, and organic matter. • Responsible for limited changes in the Earth’s surface • Soften bedrock • Two Types of Weathering • Chemical Weathering • Physical Weathering

  3. Physical Weathering • Disintegration or breaking of rock materials into smaller fragments or pieces • Rocks reduced to smaller particles over thousands or millions of years • Disintegration- material is broken down into small fragments or pieces • Chemical components of the rock remain unchanged • 6 Important Factors that expose unexposed surfaces to weathering • Frost wedging • Plants • Animals • Temperature • Exfoliation • Gravity

  4. Weathering and Water • Water is the greatest visible factor in weathering • Liquid • frozen • Frost Wedging- water seeps into cracks in rocks and goes through a freezing a thawing cycle creating large openings and cracks in rocks

  5. Weathering and Plants and Animals • Plants can also cause wedging • As plants grow roots are forced into cracks in the ground to obtain food and water • As the roots grow they cause more cracking and breaking of rocks exposing more surface to weathering • Animals move materials exposing more surface

  6. Weathering and Temperature • Temperature changes during the day and night contribute to physical weathering • Most common in very dry areas where there are large changes in temperature from day to night • Temperature Changes causes rocks to crack

  7. Exfoliation • Exfoliation occurs most rapidly in moist areas • Outer layer weathers and pulls away from the underlying surface exposing new surface to weathering

  8. Gravity • When a rock is loosened the rock will fall due to gravity • If a rock falls from a cliff it is said to be transported or moved by gravity • When it falls it will most likely break into pieces exposing new surfaces to weathering

  9. PHYSICALWEATHERING EXPOSES NEW SURFACES TO WEATHERING !!

  10. Chemical Weathering • Decomposition of rock materials due to chemical reaction of compounds in the rock with the chemicals in the environment • Chemicals react with the minerals of the rock to convert them to a new chemical compound • Decomposition- the material being chemically weathered is being chemically destroyed or changed to a different chemical compound

  11. Chemical Weathering • 2 Main forces of Chemical Weathering • Temperature • Moisture • Warmth and high moisture favor chemical reactions • Not all rocks are composed of the same chemical materials so chemical weathering affects rocks differently

  12. Erosion • A composite of all processes by which rock and soil materials are loosened or dissolved and moved from place to place • Responsible for the formation of rivers, valleys, canyons, etc. • Disintegrate rock and transport it great distances

  13. Erosion • Wind and Water are both capable or moving large amounts of materials over long distances • Obstacles on a slope will affect the erosion of soil from the slope • Rocks • vegetation: trees, grasses, and other plants

  14. Weathering and Erosion • Weathering starts disintegration of the rock • Erosion acts to carry the material away

  15. Soil • Mixture of different components • Organic Component • Remains of dead animals • Dead plants • Extremely important providing nutrients for other plants to grow • Inorganic Component • Rocks • Both weathering and erosion contribute to forming and depositing soil

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