3. Formation of the Modern Ocean Basins

Expedition Menu

1. Introduction

2. Theory

3. Formation

4. Evidence

5. Earth's Interior

6. Heat Engine

7. Mid-ocean Ridge

8. On the Ridge

9. Seafloor Spreading

10. Magnetic Field

11. Magnetic History

12. Magnetic Patterns

13. The Plates

14. More on Plates

From the animation at the left, we can see that the modern ocean basins formed as a result of the breakup of Pangea and subsequent drift of the continents. This was the one place where Wegener was wrong -- he believed that the crust forming the continents plowed through the crust below the oceans, much like a boat plowing through water.......even in the first half of the 20th century, scientists knew was not possible -- since the rocks under the seafloor are much stronger than the rocks that compose the continents (i.e. it would be like pushing a marshmallow through a block of wood). 

As we will see, as the continents drift apart, new crust is formed beneath the sea to fill the growing space and to fill the void. 

However, Wegener, and others before him, did recognize that there was an inescapable match between the coastlines across ocean basins - and by cutting a map into pieces - they could fit the continents back into single feature.

Created By:
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Don Reed
Dept. of Geology
San Jose State University
©Copyright 2008
Last Updated on 
Sept. 22, 2008

Using the map above, the shorelines of which of the following pairs of continents can be easily seen to match up across an ocean:
a)
Australia and South America
b) North America and Asia
c)
South America and Africa
d) 
Eurasian and Antarctica