Across
- 1. the chemistry of the earth's crust
- 2. evidence
- 6. the earliest eon in the history of the Earth from the first accretion of planetary material (around 4,600 million years ago) until the date of the oldest known rocks (about 3,800 million years ago); no evidence of life
- 7. the phenomena associated with volcanic activity
- 12. relating to or occurring or living in or frequenting the open ocean
- 14. movement of the edge of one tectonic plate under another
- 15. a salt or ester derived from silicic acid
- 16. molten rock in the earth's crust
- 17. the longest unit of geological time
- 18. relating to ocean depths from 2000 to 5000 meters
- 19. subject to or caused by an earthquake or earth vibration
Down
- 1. a geologist who uses physical principles to study the properties of the earth
- 3. relating to the earliest known rocks formed during the Precambrian Eon
- 4. the branch of geology studying the folding and faulting of the earth's crust
- 5. the regions of the Earth where living organisms exist
- 8. use again after processing
- 9. a grey tetravalent metallic element that resembles zirconium chemically and is found in zirconium minerals; used in filaments for its ready emission of electrons
- 10. a specialist in the history of the Earth recorded in rocks
- 11. the process of covering the earth with glaciers or masses of ice
- 13. relating to or characteristic of the crust of the earth or moon
- 20. atom with same atomic number, different number of neutrons