INTERNAL FORCES SHAPING THE EARTH

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INTERNAL FORCES SHAPING THE EARTH
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Plate Tectonics

• Internal forces that shape the Earths surface
  begin beneath the lithosphere.
• Tectonic Plates enormous moving pieces of the
  earths lithosphere.
• Geographers study the movement of the plates to
  understand how the earth is continually being
  reshaped.

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Plate Movement

• Tectonic Plates move in one of four ways
• 1. Spreading or moving apart
• 2. Subduction or diving under another plate
• 3. Collision or crashing into one another
• 4. Sliding past each other

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• When tectonic plates come into contact, changes
  on the earths surface occur.
• Boundaries mark plate movement.
• 1. Divergent Boundary plates move apart,
  spreading horizontally
• 2. Convergent Boundary plates collide, causing
  either one plate to dive under the other or the
  edges of both plates crumple.
• 3. Transform Boundary plates slide past one
  another

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Folds Faults

• When two plates meet, they cause folding and
  cracking of the rock.
• This transformation of the crust by folding or
  cracking occurs very slowly. Only a few
  centimeters or inches in a year!
• Fault a fracture in the earths crust.
• Plates move past each other at the fault line.

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Earthquakes

• Seismograph special device that can detect
  earthquakes. Measures the size of the waves
  created by an earthquake.

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• Focus the location in earth where an earthquake
  begins.
• Epicenter point directly above the focus on the
  earths surface.

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• Earthquakes result in the squeezing, stretching,
  shearing motions of the earths crust that
  damage land and structures.

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• Richter Scale determines the strength of an
  earthquake by using the information collected by
  a seismograph. The scale has no absolute upper
  limit.

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• Tsunami giant wave. Can sometimes be caused by
  an earthquake. Travels from the epicenter of the
  quake at speed up to 450 mph and can be 50 to 100
  ft or taller.

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Volcanoes

• Volcano an opening in earths surface or crust
  that allows hot magma, gases, ash escape from
  below the surface.

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• Ring of Fire zone around the rim of the Pacific
  Ocean location of the majority of active
  volcanoes. Eight major tectonic plates meet in
  this zone.

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• Hot springs geysers are indicators of high
  temperatures in the earths crust.
• Hot springs occur when ground water circulates
  near a magma chamber.