Plate Tectonics

4. the theory that the crust is divided into large pieces, or plates that slowly move on top of the mantle
5. an underwater mountain system formed by tectonic plates; largest single volcanic feature on the earth
7. the uppermost part of the mantle and the crust
12. huge piece of crust that moves slowly on the upper, ductile (soft and bendy) part of the mantle
16. a depression on Earth’s surface in which an ocean lies
17. a place where 2 tectonic plates move away from each other
18. a place where 2 tectonic plates come together and collide
19. A dark colored, extrusive igneous rock usually associated with oceanic crust
20. the thin, solid, outer most layer of the earth
21. molten material below the surface of the earth

1. up to 80 km thick, generally makes up landmasses and is usually considered to be made of granite
2. molten material that has made it to the surface of the earth
3. the mineralized remains of organisms, showing how long dead organisms lived and how their bodies were constructed
6. the part of the mantle that is almost liquid, where convection currents occur
8. solid layer of earth between the crust and the core; made of dense silicates
9. the theory that continents were once connected but have since drifted apart
10. a phenomenon by which magma from earth’s mantle comes up to the mid-ocean ridge and creates new oceanic crust
11. the process in which a denser tectonic plate is pushed downward beneath a less dense plate when plates converge
13. A light colored, intrusive igneous rock usually found on continental crust
14. 5-10 km thick, generally on the bottom of the ocean floor and is usually considered to be basalt
15. deep and narrow depression in the sea floor where the subducted plate moves into the asthenosphere