Plate Tectonics

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Plate Tectonics California
Use this lecture in conjunction with the science
textbook, Focus on California Earth Science
published by Scott Foresman
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Plate Tectonics California

• California lies on the boundaries of three plates
  (p. 236)
• The Pacific plate on the west
• The North American plate on the east
• The Juan de Fuca plate in the northwest
• Over millions of years, the movements of these
  plates produce four major geologic features in
  California faults, volcanoes, mountain ranges,
  and basins.

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California Faults

• Faults are cracks in the Earths crust that are
  often found at plate boundaries.
• The San Andreas Fault is a major fault running
  nearly the entire length of the state.
• This fault is a sliding boundary.
• The Pacific plate is moving northwest and the
  North American plate is moving west.
• As the plates push and pull, many smaller faults
  are also formed.

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California Volcanoes

• Volcanoes form at colliding plate boundaries.
• The Juan de Fuca plate is colliding with the
  North American plate in the Pacific Ocean near
  northern California.
• This creates a subduction zone, where one plate
  slides under the other and magma is formed.
• Mount Shasta and Lassen Peak are volcanoes formed
  by the subduction process.

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California Mountain Ranges

• Plate motion provides the force that pushes up
  Californias mountains.
• The Sierra Nevada, Coast Ranges, Peninsular
  Ranges, and Transverse Ranges were all formed by
  plate movement.
• The Transverse Ranges formed as a block of crust
  was rotated and squeezed upward.

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California Basins

• Plate movement sometimes causes the crust to warp
  downward into a basin, which is a broad,
  bowl-shaped valley.
• The Central Valley of California is a huge basin
  with the Sierra Nevadas on the east and the Coast
  Ranges on the west. As these mountains rose, the
  crust of the valley was pushed downward.
• There are also many smaller basins in California.

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Test Yourself!

• What are the four major geologic features formed
  by plate movement?
• What is the major fault in California called?
• How do volcanoes form at plate boundaries?
• What causes mountains and basins in California?
• Name a California volcano, mountain range, and
  basin.