Across
- 3. A mixture of copper and tin; used to make stronger tools.
- 4. floor spreading The process by which molten material adds new crust
- 5. ocean ridge An undersea chain of mountains that is part of a long
- 7. The process by which crust sinks back into the mantle at a
- 10. the echoes.
- 11. A device that reflects sound waves off underwater objects and
- 13. of underwater mountains.
Down
- 1. A person who specializes in writing and serves as a record keeper.
- 2. plate boundary.
- 4. A sharpened reed used to press markings into clay tablets.
- 6. A picture or drawing that represents a word or idea.
- 8. Earth’s bodies of water.
- 9. A type of writing made up of wedge-shaped markings.
- 12. A deep undersea valley where crust sinks towards the mantle.