GEOL107 Lecture Notes - Lecture 17: Abyssal Plain, Convergent Boundary, Continental Shelf
30 Oct 2018
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Document Summary
Where new ocean crust created - plates moving apart create gap at surface, magma from mantle rises to fill gap, magma is cooled (crystallizes) forming new oceanic crust. About 70% of all earth"s volcanic activity occurs here. Crust moving away from mid-ocean ridge is cooling and sinking (ocean depth increasing), faulted (mostly normal faults), crust is slowly being covered by oceanic sediments. Crust continuing to move away from mid-ocean ridge is cooling and sinking (ocean depth increasing), crust completely covered by oceanic sediments, smooth (little relief), flattest portions of ocean floor. Occur at convergent plate boundaries where oceanic lithosphere is being subducted, long, linear. Underwater volcanoes occur individually or as chains. Erosion by waves when seamount was near/at ocean surface. Transition between deep ocean floor and land. Extends from shoreline to water depths of 100-300 meters. Can be exposed as land during glacial time periods. Extends from continental shelf to water depths approaching 3000 m.
