The Seafloor at Birth
1. Introduction

Expedition Menu

1. Introduction

2. Plate Motion

3. Plate Motions & Boundaries

4. Example 2

5. Review

6. Rates

7. Full Rates

8. South Atlantic

9. Life Cycle of Lithosphere

10. Discussion

Contact Don Reed
Dept. of Geology
San José State University
ęCopyright 1999
Last Updated on June 21, 1999

Continental breakup
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Don's Introduction

Objective: In this expedition students will learn about the horizontal and vertical movements of the major plates of lithosphere that compose the rigid outer shell of the Earth. The movements of plates influence the shapes of seafloor features, the distribution of the major energy resources on the planet, and result in the tragic earthquakes and tsunamis that have caused hundreds of thousands of deaths.

The expedition will end with a required discussion on distinguishing science from pseudoscience, the second required learning outcome for all Area R classes at SJSU.

  • The rigid, strong surface layer of the Earth is composed of the lithosphere (between 80 and 300 kilometers-thick), which includes the crust and the uppermost part of the mantle

  • The lithosphere forms the tectonic plates that ride over top the hot, mobile asthenosphere which moves by convection (mantle convection) due to the great amount of heat released from within the Earth

  • The boundaries between the moving plates include three varieties, depending on the directions of plate motion:

    1. divergent (away from plate boundary),

    2. convergent (towards plate boundary), and

    3. transform, (parallel to plate boundary, but opposite direction on either side)

Plate Motion and Lithosphere

Let's learn the rules of plate motion