GEOG 1113 Study Guide - Midterm Guide: San Andreas Fault, Igneous Rock, Continental Drift
Document Summary
Alfred wegner; theory stated that crust is moved by vast forces within the planet. Theory of plate tectonics= 14 large plates in earth"s lithosphere move and interact forming plate boundaries. Theory challenged scientific theories that were already established at the time; lacked explanation for the cause of continental drift; wegner believed continental drift was the result of centrifugal force and tidal attraction; scientists found the argument weak. Divergent: plates moves apart; lithosphere thickens away from ridge axis; mid-ocean ridges are here also known as linear mountain ranges. Convergent: plates move together; subduction= plate consumption process; volcanic arcs (chains of volcanoes on overriding plate) are found here. Transform: plates move sideways; material is neither created nor destroyed; characterized by earthquakes and absence of volcanism; example of continental transform= the san. Lithosphere: fragmented into 20 tectonic plates; crust 250 km; oceanic crust 30 g/cm^3; crust and upper mantle; rigid and brittle.
