Plate Tectonics

4. Reptile fossil that has been found in places now separated by oceans.
5. A fernlike plant that lived 250 million years ago.
6. The way scientists mapped mid-ocean ridges in the mid-1900s.
9. A deep valley that forms where two plates move apart.
10. The process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary.
12. A plate boundary where two plates move away from each other.
13. A plate boundary where to plates move toward each other.
14. A section of the lithosphere that slowly moves over the asthenosphere, carrying pieces of continental and oceanic crust.
16. A break in Earth's crust along which rocks move.
17. Any trace of an ancient organism that has been preserved in rock.
18. German scientist who became curious about why some continents look as though they could fit together.
19. The theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle.

1. A book published by Alfred Wegener.
2. Mid-Ocean ridges that are continually adding new material to the ocean floor.
3. A plate boundary where two plates move past each other in opposite directions.
7. A supercontinent or single landmass.
8. Mountain ranges that run along the middle of some ocean floors.
11. A deep valley along the ocean floor beneath which oceanic crust slowly sinks toward the mantle.
13. The theory that the continents slowly drifted over Earth's surface.
15. Another reptile fossil that has been found in places now separated by oceans.