Plate Tectonics

6. a mountain or hill, typically conical, having a crater or vent through which lava, rock fragments, hot vapor, and gas are being or have been erupted from the earth's crust.
8. In oceanic-oceanic convergence, the denser plate sinks beneath the _______ _______ plate
10. a stress that squeezes or shortens material.
11. stress a stress that causes material to twist or become distorted.
13. the layer immediately below the lithosphere.
14. the process by which Earth's lithosphere pulls apart to form long, narrow, faulted rift valleys.
15. the hypothesis that today's continents were once one big landmass
16. boundary A tectonic boundary where two plates are moving toward each other.
19. boundary A tectonic boundary where two plates are moving away from each other.

1. convection one process thought by scientists to be a cause of tectonic plate movement.
2. boundary where the two plates slide against each other in a sideways motion.
3. the process by which new sea floor forms
4. the process by which one tectonic plate is pulled beneath another plate.
5. a stress that lengthens a material or pulls a material apart.
7. the outermost physical layer of Earth.
9. the bending, tilting and breaking of rock.
12. ground movements that occur when blocks of rock in Earth move suddenly and release energy.
17. trenches deepest land forms found on the ocean floor.
18. a system of ideas that explain many related observations about the natural world.