Chapter 2

Forces of Change

Earth's Structure

  • For hundreds of millions of years the earth's surface has been in slow but constant movement.
  • Some things change the earth such as, wind and water but these changes occur on the earth's surface.
  • Here are some other things that cause the earth to change just on the interior of the earth, volcanic eruptions and earthquakes.
  • The earth is divided into 4 layers
  • These layers are, (from outer most layer to inner most layer) Crust, Mantle, Outer Core, Inner Core.

Earth's Structure (part 2)

  • Continental Drift is the theory that all the plates of the earth were all connected but they slowly drifted apart.
  • The plates move so slowly that they only move about 4 inches a year.
  • When the plates spread apart magma is pushed up from the earths surface.
  • When two plates bump together and one plate goes under the other is called a subduction zone.
  • Scientist use the term Plate Tectonics to refer to the plates activities
  • Scientist have not yet discovered what causes plate tectonics.

Internal Forces Of Change

  • Mountains are formed by converging plates.
  • A subduction zone is where two plates collide and one plate goes under the other.
  • Earthquakes and Faulting happen when two plate slide against each other this is know as Transforming

External Forces of Change

  • There are many things that change the earth but wind and water are the main ones.
  • Here the specific names of these types of changes, Weathering, Wind Erosion, Glacial Erosion and Water Erosion.
  • These are all different ways to change the earths surface.
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