WEATHERING AND EROSION

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WEATHERING AND EROSION
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Processes that change the surface of the Earth

• Mechanical or Physical Weathering
• Chemical Weathering
• Erosion
• Tectonic Activity (volcanoes, earthquakes.etc.)

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COMMON NATURAL FORCES OF CHANGE

• Wind
• Water
• Plants
• Animals (including humans)

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MECHANICAL WEATHERING

• Rocks and other materials break apart via
  physical means - similar to physical changes in
  chemistry
• Chemical makeup stays the same
• wind, burrowing animals, plants, ice

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CHEMICAL WEATHERING

• Chemical reactions on the surface breakdown or
  dissolve the minerals in the rock or other
  material - similar to chemical changes in
  chemistry
• The chemical makeup changes
• acid rain, oxidation (rusting), plant acids,
  lichen, carbonic acid (caverns)

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EROSION

• Process by which weathered materials are carried
  away
• water, wind, ice, gravity, humans
• water is the MOST significant force of erosion

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RIVERS

• Begin as rills gtgt gullies gtgt streams gtgt rivers
• Deposit sediment as they lose energy - slow down
• Form deltas when they reach seas, oceans, gulfs,
  lakes

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Rivers cont.

• Create V shaped valleys
• Colorado River carved out the Grand Canyon over
  millions of years
• As they age the meanders increase and oxbow lakes
  may appear

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Rivers cont.

• Important to human activity
• Develops rich fertile soils
• Can be very destructive
• Provide recreation and challenges

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MASS WASTING OR MOVEMENT

• Gravity is the force behind mass movement
• Landslides, mudslides, slump, creep
• Water, lack of vegetation, steep slopes can
  create conditions that are ripe for mass movement

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WIND

• Causes abrasion - sand and small particles polish
  and smooth jagged edges
• Reshapes the landscape - sand dunes
• Can be very destructive - reach speeds over 100mph

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GLACIERS

• Create U shaped valleys - Yosemite National
  Park
• Sharp mountain peaks called Horns, Glacier Lakes
  (Minnesota, Great lakes)
• Move HUGE masses
• Studied to learn about current and past climate
  changes

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DAMS Pros and Cons

• Displace people
• destroy habitat
• interrupt fish migration
• endanger wildlife
• change flow of sediments and rivers

• Prevent flooding
• generate energy
• create lakes, reservoirs

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Human Activities

• Land Developing - housing, industry, farming
• Mining of Resources
• Damming of Rivers

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Weathering and Erosion are processes that
continue on a non stop basis.