Continental Drift.

3. A series of large waves that result from an underwater earthquake.
5. Spreading: A theory that the middle of the ocean is spreading apart, forming new oceanic crust.
7. Tectonics: The theory that the surface of the Earth is divided into a series of plates that continually moving.
8. Lithosphere; the outer layer of the Earth
13. Plate: A rigid layer of the Earth's crust that is believed to drift slowly.
14. The transfer of thermal energy by the movement of molecules in air or liquid from one place to another.
18. Ridge: A series of underwater mountains that form as a result of tectonic plates moving apart and allowing magma to rise.
19. To be reduced from a solid state to a liquid state.
20. The degree of hotness or coldness of a body or place.
21. Boundary: The boundary between two tectonic plates that are moving apart.
23. Mass: A large continuous piece of land.
25. The layer of molten rock located beneath the Earth's crust.
26. Rock that in its molten form issues from volcanos.

1. Relating to ocean depths from 2000 to 5000 meters.
2. A fracture in rock where tectonic plates have moved.
4. Trench: A deep ditch under the ocean along a tectonic plate boundary
5. The movement of one tectonic plate under another tectonic plate.
6. Plates: A large layer of solid rock that covers part of the Earth's surface.
9. Boundary: The boundary between two tectonic plates that are sliding past each other.
10. Someone who is specialised in the history of the Earth recorded in rocks.
11. Crash into each other with violent impact.
12. The regions of the Earth where living organisms exist.
15. Shelf: Underwater cliffs between the beach and ocean
16. Current: The current or flow of air or liquid that results from the transfer of thermal energy through convection
17. The centre of the Earth
22. Valley: A deep valley that forms as a result of tectonic plates moving apart on land.
24. Floor: The bottom of a sea or ocean
25. Semi-liquid rock found beneath the Earth's surface.