Chapter 4 Section 3 – The Theory of Plate Tectonics 1) Two types of crust on earth: Continental and Oceanic 2) The 3 types of plate boundaries, the motion of the plates at each, what they create and an example: (not a very good picture but this is in your comp book) 3) What is the force strong enough to move the plates? convection/convection currents 4) How and where does this happen? Convection is the entire cycle of heating, rising, cooling, and sinking that creates a current and is able to move the tectonic plates. It takes place in the mantle in the asthenosphere. 5) What is a subduction zone and where do subduction zones occur? Subduction is when two plate collide at a convergent boundary and one sinks under the other and melts back into the mantle. This happens because of density differences in the earth’s crust. The denser plate will sink. 6) When 2 continental plates collide with no subduction what does it create? Mountains 7) When 1 continental and 1 oceanic plate collides and one subducts what does it create? Volcanic Mountains 8) Review the characteristics of the Lithosphere and Asthenosphere. Lithosphere = Made up of the earth’s crust and upper mantle and this layer is all solid. Asthenosphere = Part of the mantle, plastic like (semi-liquid), tectonic plates float on this layer.