Plate Tectonic Recap and Review

Convergent Boundary Possibilities Ocean crust meets continental crust Ocean crust meets ocean crust continental crust meets continental crust Ocean crust is MORE dense and is forced UNDER the continental crust = SUBDUCTION SUBDUCTED crust is partially melted in the upper mantle – the new less dense magma makes its way UP through the rock layers SUBDUCTION ZONE creates a TRENCH on the ocean floor – the magma that rises creates a volcano on the continent. The line of volcanoes is a mountain chain (Andes) Older = colder; colder = MORE dense = sinks SUBDUCTION SUBDUCTED crust is partially melted in the upper mantle – the new less dense magma makes its way UP through the rock layer of the ocean floor SUBDUCTION ZONE creates a TRENCH on the ocean floor – the magma that rises creates a volcano in the ocean. The string of volcanoes is called an island arc (Japan) NO SUBDUCTION – Neither is significantly more dense than the other! If they can’t go down, they must go UP! The upward motion forms mountains – Himalaya

Transform Transform means? To slide past without much up or downward motion.

Because mid-ocean ridges do not diverge at the same speed all along the ridge, transform boundaries can be found intersecting the ridge. Mid-ocean ridge (divergent zone) Transform boundary

REVISIT Divergence To pull apart Most obvious areas of divergence are: Mid-ocean ridges – home of sea-floor spreading! Iceland is also a product of divergence (sits on the MAR)

Iceland’s Rift

Did you find the crack in DjiboutiDid you find the crack in Djibouti? Click to see more online!

Read this articleRead this article. List the SIMILARITIES to what is happening in Africa to the things that happen at a mid-ocean ridge. We are witnessing the way continents are pulled apart. This is DIVERGENCE on a continent.

Plate Tectonic Theory – Lithospheric “Bumper Cars” Crust Boundary Type Result? Example? (Name it and locate it on map.) oceanic divergence oceanic convergence oceanic transform continental divergence continental convergence continental transform oceaniccontinentalconvergence Mid-ocean ridge Mid-Atlantic Ridge Transform Fault Kangaroo Fracture Zone Island arc & a trench Japan & the South Sandwich trench You finish the rest!