EVSC 2800 Study Guide - Final Guide: Himalayas, Seafloor Spreading, Orogeny
12 May 2016
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Geology exam two study guide: new crust. As lava spills out into the cold ocean water it forms pillow basalts, magma that cools before reaching the surface forms sheeted dikes: ophiolite suites provide evidence of plate tectonics being active at the time. Harry hess first coined the term seafloor spreading and acknowledged that if earth"s crust was expanding along oceanic ridges, it must be shrinking elsewhere. He investigated ocean basins with emphasis on island arc systems where ocean crust subducts under ocean crust. A convergent boundary with its destruction of ocean crust became another element in the evolving theory of plate tectonics. A puzzle fit of continents bordering the present day atlantic ocean aligned matching rock types across continental boundaries. In addition, occurrences of fossils also suggested past proximity of the continents. Glacial deposits and ice-movement directions across the southern continents also suggest past juxtaposition. These observations caused speculation about the past arrangement of the continents.
