GSC 101 Lecture Notes - Lecture 3: Continental Crust, Continental Drift, Divergent Boundary
Document Summary
Crust and mantle vs. lithosphere and asthenosphere= the lithosphere contains the crust and the rigid upper mantle. The asthenosphere is the plastic part of the mantle where the lithosphere moves. Earth s bimodal surface= earth is about 50/50 above and underwater. Oceanic vs. continental crust= continental is much thicker than oceanic. Continents look like they should fit together= continental drift aka pangea. Opposition to continental drift= there was no mechanism for how the continents should have moved, basalt is too stiff for continents to move through. Midoceanic ridges and convection= something ws pushing up from the earths crust in the oceans, the hot magma heating up caused convection which made the ridge. Testing the plate tectonics hypothesis: fossil evidence and paleomagnetism. Gps evidence for plate tectonics= earthquakes and volcanoes occur more frequently at plate boundaries. Passive boundaries= between the oceanic and continental crust inside tectonic plates. Divergent boundaries (when plates move away from each other)