Learner Express: Modules for Teaching and Learning
In the 1950s, scientists using sonar mapping discovered that the Earth's ocean floors are not flat, but marked by a surprising array of undersea volcanoes, mountain ranges, and trenches. Geologist Keith Klepeis of the University of Vermont discusses how these features are the signature evidence of the movement of more than a dozen rigid plates that cover the Earth's surface, including both the continents and the sea floor. Earthquakes can result from the sudden release of tension that builds up at plate margins as plates move past or over each other. Earthquakes are, therefore, indicators of plate motion. Run Time: 00:04:23
D. Structures of the Earth: Crustal plates constantly move in response to the movements of the mantle.
Continental Drift
What Seismic Waves Tell Us