Plate Tectonics - The Dynamic Earth

You may wish to print a copy of the lecture outline on Plate Tectonics(minus the illustrations) and you have two options:

• Microsoft Word if you use that Word Processor or
• A Netscape Document that you can print (use the Left Arrow key to return to this page).
• Or, you may view the Plate Tectonics power point presentation shown in class.

Chapter Objectives

After reading Chapter Nineteen, you should be able to:
1. Explain the idea of continental drift, compare it with the modern plate tectonics and list the evidence supporting this theory.
2. Illustrate how Earth's magnetic field affects rocks on the Earth's surface, and explain how this relates to continental drift.
3. Define seafloor spreading, and describe how reversals in the Earth's magnetic field appear on the seafloor.
4. Illustrate the types of plate boundaries and their features.
5. Cite recent evidence that supports the theory of plate tectonics.
6. Describe the possible mechanisms driving plate tectonics.

Introduction

When I was an undergraduate in 1961, our Geology Club organized a debate in which faculty teams would discuss the "pros and cons" of the theory of Continental Drift. Not one of the 10 faculty wanted to be on the "pro" side so they formed their teams by drawing straws. Today, the opposite would be true in our department. The world map above used radar altimetry to reflect the underlying topography of the oceans and continents. Note that many of the plate boundaries are clearly defined. I would hope that everyone who takes this course leaves with a better understanding of the Earth and how it works. The lead resource is a good thing to read at this time.

Class Notes

Internet Resources

1. Review - Plate Interactions

2. Plate Tectonics - the Cause of Earthquakes In the early 1960s, the emergence of the theory of plate tectonics started a revolution in the earth sciences. Since then, scientists have verified and refined this theory, and now have a much better understanding of how our planet has been shaped by plate-tectonic processes. We now know that, directly or indirectly, plate tectonics influences nearly all geologic processes, past and present. Indeed, the notion that the entire Earth's surface is continually shifting has profoundly changed the way we view our world."

3. Plate Tectonics from the United States Geological Survey

   "Convergent Boundaries ... "Hot Spots" ... Plates ... Plate Tectonics ... "Ring of Fire"... Sea-Floor Spreading ... Spreading Ridges ... Subduction Zones ... Submarine Volcanoes ... "

A Virtual Field Trip to Mount Saint Helens

The Cascade mountain range in the Pacific northwest is a geologically active area. The Juan de Fuca plate is moving to the east and is being subducted beneath the North American plate which is moving the west. Review the before and after aspects of the most recent eruption of Mount Saint Helens