EESA06H3 Lecture Notes - Lecture 4: Lava Lake, Volcanic Glass, Shield Volcano
Document Summary
Lecture 4- east african rift: how oceans are born . The cyclical opening and closing of ocean basins caused by movement of the earth"s plates. The wilson cycle begins with a rising plume of magma and the thinning of the overlying crust. As the crust continues to thin due to extensional tectonic forces, an ocean basin forms and sediments accumulate along its margins. Subsequently subduction is initiated on one of the ocean basin"s margins and the ocean basin closes up. When the crust begins to thin again, another cycle begins. The wilson cycle is named after the canadian geophysicist j. tuzo wilson (1908-1993). One land/continent then there is continental rifting. Pangea, also spelled pangaea, in early geologic time, a supercontinent that incorporated almost all of earth"s landmasses and covered nearly one-third of earth"s surface. Pangea was fully assembled by the early permian period, some 270 million years ago.
