define tetonic activity
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Answer:
he theory of continental drift was first proposed by Alfred Wegener in 1915. It had long been noted that continental coastlines appeared to fit together like giant puzzle pieces, most notably the west coast of Africa and the east coast of South America. Wegener hypothesized that a supercontinent, named Pangaea, existed 200 million years ago; this supercontinent subsequently broke apart in to several continental pieces. Since Wegener's hypothesis, substantial fossil and geological evidence has been compiled to validate continental drift theory.
Lithosphere and Asthenosphere
Continental drift is explained through the activity of tectonic plates. According to plate tectonics theory, the Earth's lithosphere, which is composed of the crust and a portion of the upper mantle, is broken into plates that float independently on top of the more liquid asthenosphere. There are eight major plates and many minor plates, which move relative to each other at plate boundaries. Plate boundaries are defined as convergent or colliding, divergent, or transform.
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