GEOL 1001 Chapter : Geology Review Chapter 2
Document Summary
The lithosphere, earth"s strong rigid outer shell of rock is broken into about a dozen plates, which slide past, converging with, or separate from each other as they move over the weaker, ductile asthenosphere. The theory of plate tectonics describes the movement of plates and the forces acting on them. The basic ideas of plate tectonics were put together as a unified theory of geology about 50 years ago. The scientific synthesis that led to the theory of plate tectonics, however, really began much earlier in the twentieth century, with the recognition of evidence for continental drift. The concept of continental drift, large scale movements of continents, has been around for a long time. Identical types of rocks and fossils have been found on different continents, leaning towards the concept that there used to be a supercontinent called pangaea. Geologic evidence was not enough to make skeptics believe the theory of continental drift.
