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Across 2. transfer of heat through the movement of a fluid material. 3. chain of volcanic island formed along an ocean trench. 6. undersea mountain range with a steep narrow valley along the center. 9. thin outer shell of the earth consisting of the crust and the rigid upper mantle. 11. border formed by the direct collision of two lithosphere plate. 15. system of undersea mountain ranges that wind around the earth. 16. single landmass thought to have been the orgin of all continents. 17. theory that the lithosphere a make up of plates that float on the asthenosphere. 18. giant ocean surrounding pangaea.

Down 1. hypothesis stating that the continent once formed a single landmass broke up and drifted to their present location. 4. zone of mantle beneath the lithosphere that consists of slowly moving rocks. 5. movement of the ocean floor away from either side of a mid ocean ridge. 7. boundary formed by two lithospheric plates that are moving apart. 8. movement in a fluid caused by uneven heating. 10. material that makes up landmasses. 12. material that makes up the ocean floor. 13. deep valley in the ocean floor that form along a subduction zone. 14. steep narrow valley formed as lithosphere plates separation.