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Plate Boundaries Lithospheric Plates are pushed and pulled around by the underlying convection cells in the upper mantle (Asthenosphere). What is a plate boundary and what happens at plate boundaries? ARABIAN PLATE INDIAN PLATE SCOTIA PLATE What is a plate boundary and what happens at plate boundaries? 3 types of plate boundaries • Convergent • Divergent • Transform Convergent Boundaries Convergent plate boundaries are locations where lithospheric plates are moving towards one another. Divergent Boundaries Divergent plate boundaries are locations where plates are moving away from one another. • This occurs above rising convection currents. • As plates move apart new material is erupted to fill the gap Transform Boundaries Plates slide past each other laterally. 2 types of crust • Oceanic • Continental Ocean-Ocean (O-O) Divergent Convergent MOR Trenches Volcanoes Volcanoes EQ EQ Trenches Ocean-Continental (O-C) xxxxx Volcanoes EQ Transform EQ RARE Volcanoes EQ Rift Valley Continental- Volcanoes Mountains Continental (C-C) EQ EQ EQ Convergent Boundary Types There are 3 types: - Ocean – Ocean - Ocean – Continental - Continental – Continental (O-O) (O-C) (C-C) O-O Convergent Boundary • When two oceanic plates collide, one runs over the other which causes it to sink into the mantle forming a subduction zone. • The subducting plate is bent downward to form a very deep depression in the ocean floor called a trench. • The worlds deepest parts of the ocean are found along trenches. O-C Convergent Boundary • Oceanic plate subducts underneath the continental plate • Oceanic lithosphere heats and dehydrates as it subsides • The melt rises forming volcanoes C-C Convergent Boundary • Continental plates collide with other continental plates and pushes up tall mountains Divergent Boundary Types There are 2 types: - Ocean – Ocean - Continental – Continental (O-O) (C-C) O-O Divergent Boundary Can you locate where the plates are diverging? Where they are coming apart, a mid-ocean ridge forms. Courtesy of www.ngdc.noaa.gov C-C Divergent Boundary Iceland has a divergent plate boundary running through its middle called a rift valley C-C Divergent Boundary Iceland has a divergent plate boundary running through its middle. Transform Boundaries There are 2 types: - Ocean – Ocean - Continental – Continental (O-O) (C-C) O-O Transform Boundary Most transform faults are found in the ocean basin and connect offsets in the mid-ocean ridges. C-C Transform Boundary San Andres is an example of a Transform Fault Line Plate Tectonics • http://www.age-of-thesage.org/tectonic_plates/boundaries_bounda ry_types.html • http://en.docsity.com/news/education2/plate-boundaries-geologic-structuresexplained-animated-gifs • http://geology.com/nsta/transform-plateboundaries.shtml