University of Phoenix Material

Effects of the Motions of Tectonic Plates Worksheet

From Visualizing Earth Science, by Merali, Z., and Skinner, B. J, 2009, Hoboken, NJ: Wiley. Copyright 2009 by Wiley. Adapted with permission.

Part 1

This diagram was similar to one Alfred Wegener drew to show the distribution of continents 300 million years ago. His theory of continental drift was met with skepticism in the scientific community.

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1. Describe three forms of evidence Wegener used to support his ideas of continental drift. Wegener used landorms, climate, and fossils to support his theory of continental drift. He said that when it came to landforms all the continents seemed to fit like a “jigsaw puzzle”. Even went as as far to say the mountain ranges seemed to line up as well. Wegener said that the same fossils and rock from one continent would end up on a different continent. For instance a fossil found in Africa would also be found in South America. When it came to climate, Wegener said that some fossils did not match the climate. For instance, there a glacier scratches in South Africa.

2. Years later, the continental drift theory reemerged as plate tectonic theory, with two additional pieces of evidence.

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Refer to the images above. Discuss in detail the two pieces of additional evidence that supported Wegener’s theory, now known as the theory of plate tectonics. The first image shows the ages of the banded rocks on the mid-atlantic range. By looking at the image you can see the the middle (yellow streak) is the youngest while the rock on the outer edges are the oldest showing that the seafloor has ben spreading over time. The second image shows surface motion and how all the points on the same plate are mostly moving in the same direction