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Changing the earth’s relief

Changing the earth’s relief. Evolution of the landscape. Changing the earth’s relief: mountain formation. Relief = shape of the earth surface Formation of mountains = Orogenesis  through convergent tectonic plate movements  mountain: - steep slopes

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Changing the earth’s relief

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  1. Changing the earth’s relief Evolution of the landscape

  2. Changing the earth’s relief: mountain formation • Relief = shape of the earth surface • Formation of mountains = Orogenesis  through convergent tectonic plate movements  mountain: - steep slopes - at least 600m high • Mountains in the making: • Himalaya, Rocky mountains, Alps

  3. ? Why are they different? Laurentians Rocky Mountains

  4. Montreal streets : After the winter: worn down

  5. ? Why are they different? Laurentians Rocky Mountains ! Laurentians a lot older  have been worn down

  6. Weathering • Gradual destruction of rock on the earth surface. • http://www.youtube.com/watch?v=z2nwiba0N0Y

  7. Mechanical weathering The power of water: Rock is fragmented, but not changed in its composition

  8. Mechanical weathering • Fragmentation of rock through: - Variations in temperature and pressure - water example: freeze thaw cycle of water - wind • Composition of rock does not change

  9. Chemical weathering Minerals in rock are dissolved and changed.

  10. Chemical Weathering • Dissolvingandchangingmineralsin rocks Composition of rock changes. • Through: - washing out of certain minerals  enhanced through acid rain

  11. Biological Weathering Living organisms destroy rock.

  12. Biological weathering • Plant roots can break rocks • Living organisms release acids  changes and weakens the rock

  13. Practice: what kind of weathering? 2 1 2. Chemical 1. Mechanical 3 3. Mechanical + Chemical

  14. Water erosion

  15. Glacial erosion

  16. Wind erosion

  17. Erosion of soil • Soil Erosion rates on farmed land between 17 and 40 tons per ha and year • average natural soil production only 1 ton per ha and year !!!

  18. Journey’s end: Deposition

  19. The three stages of Erosion Erosion 1.) Weathering 2.) Transport: water, wind, ice 3.) Deposition: in lake, stream, ocean

  20. Changing the earth’s relief: Erosion • Erosion is the gradual wearing away (destruction and /or removal) of land surface material, for example rock or soil. • Three step process: • Weathering of rock (destruction of rock) • Transportation of soil and rock debris (through water, wind, glaciers). • Deposition of material at another location

  21. View from the mountain:

  22. Montréal

  23. Montréal

  24. Effects of erosion • Hole on Sherbrooke May 2012 • Caused by hole in water collecting pipe • What happened?

  25. homework • Worksheet to be collected next class

  26. Categories of Weathering / Erosion • Mechanical Weathering • Composition of rock does not change • Through: - Variations in temperature and pressure  example: freeze thaw cycle of water - Wind and water • Chemical Weathering • Composition of rock changes • Through: - washing out of certain minerals  enhanced through acid rain • Biological Weathering • Living organisms release acids  change + weaken the rock • Plant roots can break rocks.

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