Chapter 21, Problem 42A

Summary Introduction

To write:

How plate tectonics explains why similar organisms can be associated on distanct continents.

Introduction:

The plate tectonics theory states that the crust of the earth is broken into rigid plates which move slowly over the surface of the earth. The plates form the outer layer of Earth- the lithosphere. The tectonic plates are a part of the lithosphere that travels gradually through the asthenosphere, bearing fragments of continental and oceanic crust.

Explanation of Solution

The study of rock strata on different places showed the presence of similar kind of fossils no matter where the rocks were found. Scientists inferred that all strata of the same age contained similar kind of fossils. Thus, fossil evidences such as rocks made of similar substances found on distant continents support the theory of plate tectonics. It shows that the earth's crust was once a whole. Identical fossil found on different continents suggests that the continents were once joined before breaking apart.

Conclusion

The presence of similar fossils on identical rock strata supports the theory of plate tectonics and explains why similar organisms can be associated on distant continents.