Postulates

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Contents
Postulates
  • Plate Postulate
    • A mosaic of rigid geologic plates covers the Earth’s surface, forming the Lithosphere.
  • Movement Postulate
    • The plates move horizontally relative to each other on top of a thick layer of molten rock, the Asthenosphere.
  • Boundary Postulate
    • Contiguous plates converge, diverge, or slide past one another.
Plate Postulate

A mosaic of rigid geologic plates covers the Earth’s surface, forming the Lithosphere.


Countries in Gray, Plate in Color, Source

View Interactive NASA Animation of Plate Boundaries on a Rotating Globe

Movement Postulate

The plates move horizontally relative to each other on top of a thick layer of molten rock, the Asthenosphere.

  • Lithosphere
    • Where the plates live
    • Rigid rocky outer layer of Earth
    • Consists of the crust and the solid outermost layer of the upper mantle.
    • 30-60 miles deep
  • Asthenosphere
    • What makes the plates move
    • Layer of molten rock lying beneath the lithosphere
    • Convection currents within the asthenosphere affect the lithosphere
    • Extends from 60 miles below the Earth’s surface to about 450 miles.

Boundary Postulate

Contiguous plates converge, diverge, or slide past one another.

Where the Plates Meet
  • Convergent Boundaries
    • A. Oceanic subducts under Continental
    • B. Oceanic subducts under Oceanic
    • Continental subducts under Continental
  • Divergent Boundary
  • Transform Boundary
Convergent Boundaries
Divergent Boundary
Transform Boundary