Geography Chapter 2.4 external forces


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Geography Chapter 2.4 external forces

  1. 1.  Wind, heat, cold, glaciers, rivers, and floods alter the surface of the earth. The results of weathering and erosion change the way humans interact with the environment.
  2. 2.  Weathering is the physical and chemical processes that change the characteristics of rock on or near the earth’s surface Can change landscapes over time and create soil for plant life - Occurs slowly over MANY years, even centuries
  3. 3.  The image shows weathering of sandstone and shale. The steep cliffs are made up of weathering resistant sandstone, while the slope at the base of the cliff is composed of rock units containing a larger abundance of shale.
  4. 4.  The surface pattern on this pedestal rock is honeycomb weathering, caused by salt crystallization. This example is at Yehliu, Taiwan.
  5. 5. • A maze of hoodoos in Bryce Canyon NationalPark in southern Utah in the early morning. Thisphoto was taken on a sunny day in May 2002.
  6. 6.  Weathering creates smaller and smaller pieces of rock called sediment.  -Sediment can be identified as fine particles of rock such as mud, sand, silt, etc.
  7. 7.  Processes that break rock into smaller pieces  - Does not change the composition of the rock – ONLY ITS SIZE!  - Many factors can contribute to mechanical weathering including; water, ice, wind, plants, animals and even humans!
  8. 8.  Occurs when rock is actually changed into a new substance due to the interactions of the elements in the air, water or minerals.  - Climates that are warm and moist will produce more chemical weathering than cool dry areas.
  9. 9. Sea caves form fromcarbonation, a type ofchemical weathering.
  10. 10.  Occurs when weathered material is moved by the action of wind, water, ice, or gravity.  Ex. Water carrying topsoil from a hill into a river will cause the river to narrow.
  11. 11.  1) when water flows in a stream or river, picks up loose material and moves it downstream
  12. 12.  2) abrasion, grinding away of rock by transported particles
  13. 13.  3) water dissolves chemical elements in the rock (changes composition of rock)
  14. 14.  When a river enters an ocean, the sediment is deposited in a fan-like landform
  15. 15. Mississippi River Delta
  16. 16.  Waves on a coastline may also change the land Waves can reduce or increase beaches Sediment from waves may build up sand bars or islands
  17. 17. Double troubleDana Goegelman looks over thedamage and erosion to the beachbeside her parents hotel inIndiatlantic, on Tuesday, Sept. 28,2004. The Casablanca Inn wasdamaged by Hurricane Francesand then later lost much of itsbeach and walkway to erosionwhen Hurricane Jeanne poundedthe Florida coast on Sunday. (AP/Dave Martin / September 28,2004)
  18. 18.  loess (LOH•uhs)  windblown silt and clay sediment that produce very fertile soil  silt – fine sand carried by moving water
  19. 19. A typical loess exposure insouthern Illinois
  20. 20.  The Mississippi River Valley in the U.S. and grasslands of Argentina have extensive amounts of loess.
  21. 21.  May produce new landforms (sand dunes) Similar to water erosion, the wind transports and deposits sediments in other locations
  22. 22.  glaciers  large, long-lasting mass of ice  move because of gravity  form in mountainous areas  form in heavy snowfall regions
  23. 23.  the changing of landforms by slowly moving glaciers  Erosion occurs when glaciers move
  24. 24.  When glaciers move, they carry rocks with them Rocks left behind by a glacier may form a hill or ridge called a moraine
  25. 25.  Who you callin’ a moraine!?
  26. 26. Different kinds of moraines on and near Gornergletscher, Valais,Switzerland: 1 - lateral moraines, 2 - middle moraines, 3 - terminalmoraine (this moraine was deposited during the Little Ice age by thesmall cirque glacier of which two remnants remain, above and aboveleft of the letter "3".
  27. 27.  hyoo-muhs the organic material in soil
  28. 28. humus
  29. 29.  1) parent material 2) relief 3) organisms 4) climate 5) time
  30. 30.  The variety of soils – and the climates in which they’re found – determine what can grow there.