The Earth in Motion

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The Earth in Motion

• Created by Mrs. Glenn

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• Our lithosphere is made up of many large plates
  Oceanic and Continental
• The plates are moving several cm/yr.
• As the plates move, the continents also move or
  drift, over Earths surface.
• German Scientist, Alfred Wegener , realized that
  over millions of years, the continents moved
  together as a super continent called Pangaea and
  then separated again.

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Continued

• Millions of years later, Pangaea slowly broke
  apart.
• The continents then moved into their present day
  location.
• This is known as the idea of continental drift.

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Plate Tectonics

• The Earths plates are in constant slow motion.
  This explains how Earths plates form and move.
  It also explains how plates interact, producing
  volcanoes, mountain ranges, earthquakes, and
  features on the ocean floor.

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Earthquake

• Earthquakes are a reminder that the Earths crust
  can move.
• An earthquake is the shaking and trembling that
  results from the movement of rock beneath Earths
  surface.

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• The movement of Earths plates creates powerful
  forces that squeeze or pull the rock in the
  crust.
• These forces cause a stress on the rock.
• Shearing, tension, and compression work over time
  to change the shape and volume of rock.

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Stress

• Shearing Stress that pushes a mass of rock in
  two opposite directions.
• Tension Pulls on the crust, stretching rock so
  that it becomes thinner in the middle.
• Compression Squeezes rock until it folds or
  breaks.

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• When enough stress builds up on a rock, the rock
  breaks, creating a fault.
• A fault is a break in the crust where slabs of
  crust slip past each other.
• Faults usually occur along plate boundaries,
  where the forces of plate motion compress, pull,
  or shear so much that the crust breaks.

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• Strike Slip Fault the rocks on either side of
  the fault slip past each other sideways with
  little up or down motion.

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• Normal Fault the fault is at an angle, so one
  block of rock lies above the fault, while the
  other block lies below the fault.
• Hanging wall above the fault
• Foot wall below the fault

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• Reverse Fault Compression forces produce
  reverse faults. This has the same structure as a
  normal fault, but the blocks move in the opposite
  direction.

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Uplift

• The forces of plate movement can build up Earths
  surface. Over millions of years, fault movement
  can cause uplift, changing a flat plain into a
  towering mountain range or plateau.

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Volcanoes

• During a volcanic eruption, the gases dissolved
  in magma rush out, carrying the magma with them.
  Once magma reaches the surface and becomes lava,
  the gases bubble out.

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Stages of a Volcano

• An active, or live, volcano is one that is
  erupting or has shown signs that it may erupt in
  the near future.
• A dormant, or sleeping, volcano is like a
  sleeping bear. It will erupt one day.
• An extinct, or dead, volcano is unlikely to erupt
  again.

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Volcano Hazards

• During a quiet eruption, lava flows pour from
  vents, setting fire to and then burning
  everything in their path. During an explosive
  eruption, a volcano can belch out hot, burning
  clouds of volcanic gas, ash, cinders, and bombs.

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Burnin Ring of Fire

• The Ring of Fire is a zone of frequent
  earthquakes and volcanic eruptions that circles
  the basin of the Pacific Ocean. It is shaped like
  a horseshoe and it is 40,000 km long. It is
  associated with a continuous series of oceanic
  trenches, island arcs, and volcanic mountain
  ranges and/or plate movements.

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