PLATE TECTONICS

The lithosphere is divided into huge slabs called plates which ride on the surface of the asthenosphere.

Heat from the core and mesosphere warms the bottom layer of the asthenosphere which creates convection cells due to the rising of the less dense, warmer magma.  This magma cools at the upper reaches of the asthenosphere, moves laterally and begins to sink as it cools thus dragging the lithospheric plates. In the two-tier model, there are also larger, slower convection cells in the mesosphere.  The lithospheric plates can then diverge, converge or shear relative to each other depending on the direction of motion of the plates.

Each of these plate motions can be used to explain geological phenomenon such as folded mountains, volcanoes, earthquakes and geysers.   Be sure to study the graphic designs distributed in class.

crust, mantle, outer core, inner core, lithosphere, asthenosphere, convection cell, earthquake, seismograph, seismic waves (P-, S-), magnetic stripes, volcano, folded mountains, continental drift, sea floor spreading, plate tectonics model, divergent, convergent, shear, continental rock, oceanic rock

Last updated   January 5, 2006
Any questions: Dr. Baker
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