GEOLOGY 1 Chapter Notes - Chapter 4: Continental Collision, Volcanism, Asthenosphere
Document Summary
Ocean floor 250 million years, furthest back recording date. Rigid lithosphere is broken into plates that move relative to one another over. Movement is driven by motion within the mantle. Explains global pattern of: earthquakes, volcanoes, etc (get from pres) Heavy, dense stuff drawn towards interior/towards core. Core (most dense) fe-ni and liquid, mantle (denser) ultramafic solid and mostly. These designations are compositional and physical rigid but ductile, crust (least dense) felsic and mafic, rigid. Divergent: plates move away from each other. If we have this must be compensated by convergence, vice versa. Oceanic divergence mid ocean ridge, seafloor spreading. Seafloor spreading at mid ocean ridge: asthenosphere coming up to the surface (hot), crack in the lithosphere opening up and the stuff comes up melting (basically lava) and cools forming a new ocean crust. There is a ridge because the asthenosphere coming up is hot and forming ocean crust (hotter things are less dense)
