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Chapter 8 Part 1

Chapter 8 Part 1

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Chapter 8 Part 1

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  1. Chapter 8Part 1 Weathering, Soils and Mass Movement GRB Pages 62 - 71

  2. Weathering and Erosion • Weathering - Def. - the break down of rocks that have been exposed to the atmosphere. • Once the rocks are broken down, the pieces are transported from one place to another. This process is callederosion. • Erosion is caused by wind, moving water (streams, waves, ocean currents), ice (glaciers), and by gravity. • VIF - Most erosion that takes place on Earth is caused by moving water

  3. Chemical weathering – rocks break down as their minerals change in composition (they become different substances). Mechanical weathering– rocks are broken down into smaller pieces without changing their composition (what they’re made of). AKA - physical weathering 2 Types of Weathering

  4. Types of Mechanical Weathering - #1 • Ice wedging/frost action • water enters small cracks in the rock. • When it freezes, it expands and forces the crack to open more. • The process repeats over again until the rock breaks apart.

  5. Mt. Brewster – looks solid, right?

  6. Close up shows jagged rocks from FROST wedging!

  7. Eventually, the rock splits from repeated frost action!

  8. Types of Mechanical Weathering - #2 • Abrasion • It is the physical wearing down of rocks as they rub or bounce against each other. This process is most common in windy areas, under glaciers, or in stream channels. • It can also happen during rock slides

  9. Types of Mechanical Weathering - #3 • Wetting and drying • breaks up rocks that are made from clay. • When they are wet they expand, and they shrink as they dry. • As this repeats over and over, the clay becomes weak and cracks (think of all the projects you have made out of clay…they all crack and fall apart)!

  10. Types of Mechanical Weathering - #4 • Exfoliation • soil and rock is removed (glaciers or uplifting), exposing rock found deep underground. • This releases the pressure causing the surface of the rock to expand and eventually crack.

  11. Types of Mechanical Weathering - #5 • Plant Roots • The roots of trees often wedge in between cracks in rocks and force apart rocks even further!