Horizon Plate Tectonics

2. The layer of rock that forms the outer surface of the Earth.
3. A weak spot in the Earth's crust where magma has come through the surface.
9. Molten rock that is found under the surface of the Earth.
10. The idea that the continents move slowly across the Earth's surface.
12. Vibrations that travel through Earth.
14. Fossils of this fern-like plant were found on five different continents and help support the theory of continental drift.
17. How geologists refer to a volcano that seems to be asleep.
19. The process that glues together particles of sediment.
20. When a portion of more-dense (usually oceanic) crust sinks under a less-dense portion of the Earth's crust.
21. The process that breaks rock down into sediment using the forces of wind, water and gravity.

1. The type of heat transfer that occurs in the Earth's mantle.
2. The transfer of heat between two objects that are touching.
4. A place where two tectonic plates slide past each other sideways.
5. A place where two tectonic plates come together and sometimes form a mountain range.
6. The name of the supercontinent thought to exist about 250 million years ago.
7. A place where two tectonic plates move away from each other.
8. The type of rock that makes up most of the oceanic crust.
11. The last name of the scientist who came of with the theory of continental drift.
13. The shaking that results from a sudden shift in a transform boundary.
15. The island nation in the north Atlantic where a rift valley can be observed.
16. The layer of the Earth's mantle on which the lithosphere floats.
18. The amount of mass in a specified amount of a substance.