EARTHSC 1G03 Lecture Notes - Lecture 4: Oceanic Crust, Plate Tectonics, Continental Crust
4 Oct 2016
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The theory of plate tectonics states that earth is divided into rigid plates which are in constant motion. Plates: regions encircled by seismic (earthquake) belts are thin, rigid slabs of crust. * asthenosphere: solid, but flows like a liquid: continents are not ships sailing" across oceanic crust, but cargo on a gigantic conveyor belt of oceanic crust. wegener, 1915. There are 3 principal types of plate boundaries: divergent boundaries two plates are moving away from one another and crust is created, volcanoes active at site of divergence; magma cools to form new crust, earthquakes common. Mors such as the red sea and gulf of. California both will continue to widen if things continue as they are: convergent boundaries two plates are colliding with one another and crust is recycled , three types, ocean to ocean. Cooler ocean plate* subducts beneath island arcs (surrounded by oceanic crust) creating a deep sea trench.
