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Rocks and Weathering

Rocks and Weathering. Which mountain range is older?. The Sierras are rocky and steep, higher than the Appalachians. The Appalachians are more rounded and gently sloping, and are covered with soil and plants. Which mountain range is older?.

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Rocks and Weathering

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  1. Rocks and Weathering

  2. Which mountain range is older? The Sierras are rocky and steep, higher than the Appalachians. The Appalachians are more rounded and gently sloping, and are covered with soil and plants.

  3. Which mountain range is older? The Sierras formed within the last 10 to 20 million years ago. The Appalachians formed more than 250 million years ago.

  4. Q: How can you tell that the Sierra Nevadas formed much more recently than the Appalachians?

  5. How is Earth's surface shaped? 1. Weathering- the process that breaks down rock and other substances at Earth's surface. 2. Erosion- the transportation of sediment by wind, water, ice, or gravity. weathering vs. erosion video

  6. Q: What is the difference between weathering and erosion?

  7. The principle of uniformitarianism -an assumption that the same processes that operate today operated in the past.

  8. Two Types of Weathering Mechanical- When rock is physically broken into smaller pieces. Keep the same chemical composition. Chemical- The process that breaks down rock through chemical changes.

  9. Is this the cause of mechanical or chemical weathering? Plant growth

  10. Is this the cause of mechanical or chemical weathering? oxidation

  11. Is this the cause of mechanical or chemical weathering? weak acid from plant roots or lichens

  12. Is this the cause of mechanical or chemical weathering? freezing and thawing

  13. Ice wedging 1st - water seeps into cracks of rocks 2nd- water freezes 3rd - water expands when it freezes and breaks rock

  14. Is this the cause of mechanical or chemical weathering? pressure release

  15. The causes of mechanical weathering • freezing and thawing • release of pressure • plant growth • actions of animals • abrasion

  16. The causes of chemical weathering • water dissolves minerals • oxygen combines with iron in the presence of water forms rust (oxidation) • carbon dioxide dissolves in water to form carbonic acid • living organisms- root tips and lichens can form weak acid • acid rain is formed when pollutants combine with water vapor

  17. What determines how fast weathering occurs? • surface area • type of rock • climate

  18. Increasing the surface area of rock increases the rate of a chemical reaction

  19. Q. Which type of stone weathers faster? granite marble - dissolves in acid, and is more permeable

  20. Climate Weathering is faster in hot and wet climate.

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