Bonus

3. An oxide of silicon with the chemical formula SiO2
7. A mixture of molten or semi-molten rock
8. The molten rock expelled by a volcano during an eruption
9. A tube of metal, plastic, or other material used to convey water, gas, oil, or other fluid substances
11. Boundary A linear feature that exists between two tectonic plates that are moving away from each other
12. The reduction in volume causing an increase in pressure
13. No longer in existence
14. A rupture in the crust of a planetary-mass object
18. A response to pressure
19. Valley A linear-shaped lowland between several highlands

1. Temporarily inactive
2. Where two plates meet
3. Break off or cause to break off, owing to a structural strain
4. Arc A curved chain of volcanic islands located at a tectonic plate margin
5. The sideways and downward movement of the edge of a plate of the earth's crust into the mantle beneath another plate.
6. A supercontinent that existed during the late Paleozoic and early Mesozoic eras
10. Earth's crust and upper mantle are made out of these
15. A roughly circular depression in the ground
16. Any preserved remains, impression, or trace of any once-living thing from a past geological age
17. An opening that allows air, gas, or liquid to pass out of or into a confined space