Plate Tectonics

3. tectonics is a scientific theory that explains how major landforms are created as a result of Earth's subterranean movements
4. the border between two plates
7. where two plates slide past one another
8. when one plate sinks under another
9. the rigid outer part of the earth, consisting of the crust and upper mantle

1. when two tectonic plates move away from each other
2. when two plates come together
5. long, narrow depressions on the seafloor that form at the boundary of tectonic plates where one plate is pushed, or subducts, beneath another
6. cracks in the earth's crust along which there is movement