Tectonic plates

2. the movement or study of the movement of Earth's crust
4. the branch of geology studying the folding and faulting of the earth's crust
6. a celestial body that revolves around the sun
8. relating to or occurring or living in or frequenting the open ocean
11. movement of the edge of one tectonic plate under another
12. molten rock in the earth's crust
14. relating to ocean depths from 2000 to 5000 meters
16. a property used to characterize materials in reactions that change their identity
19. atom with same atomic number, different number of neutrons

1. the regions of the Earth where living organisms exist
3. of or relating to the earliest known rocks formed during the Precambrian Eon
5. the process of covering the earth with glaciers or masses of ice
7. a large continuous extent of land
9. a rigid layer of the Earth's crust that is believed to drift slowly
10. the phenomena associated with volcanic activity
11. the bottom of a sea or ocean
13. science of the history of the earth as recorded in rocks
15. the chemistry of the earth's crust
17. a grey tetravalent metallic element that resembles zirconium chemically and is found in zirconium minerals; used in filaments for its ready emission of electrons
18. a geologist who uses physical principles to study the properties of the earth