Chapter 6 Questions
The Active Earth: Plate Tectonics
1). a. Briefly describe Alfred Wegener's theory of continental drift.
b. What evidence supported his ideas?
2. Briefly describe the sea-floor spreading hypothesis and the evidence used to develop the hypothesis
(make sure to mention how the mid-oceanic ridge system, magnetometers, mud thickness and fossils
played in role in this hypothesis).
3. The continental drift and seafloor spreading hypothesis' provide the basis for the larger theory of plate
tectonics. Questions: a. How does Wegener's theory differ from the modern theory of plate tectonics?
b. Why is a unifying theory, such as plate tectonics theory, desirable in any field of science?
4. The Earth is a layered planet, the major layers being the crust, mantle and the core. This was not known
during Wegener's time, and is necessary to understand the theory of plate tectonics. Seismic waves
generated during earthquakes help geologists map the interior of the Earth. Questions: a. Describe the
physical properties of the crust, mantle and core. (hint, there is a table in your book that will help answer
this).
b. What is the lithosphere and asthenosphere (i.e., describe and explain the important differences between
the lithosphere and the asthenosphere).
