4. a plate boundary where two plates

move towards each other

10. the soft layer of the mantle on which the lithosphere floots

11. the layer of rock that forms earths outer surface 14. a trace of an ancient organism that

has been preserved in rock

17. the theory that pieces of earths lithosphere are in constant motion driven by convection currents in the mantle

19. an undersea mountain chain where new ocean floor is produces

20. the name of the single landmass that broke apart 200 million years ago and gave rise to todays continents

Down

1. a ridged layer made up of the uppermost part of the mantle crust 2. rock that floats high on the mantle that makes up the continents

3. The layer of hot solid material between earths crust and core

16. a break or crack in earths lithosphere along which the rocks move 5. a plate boundary where two plates

move away from each other 6. The hypotheses that the continents slowly move across Earth's surface

7. a plate boundary where two plates move past each other in opposite directions

8. a deep valley along the ocean floor beneath which oceanic crust slowly sinks toward the mantle

9. a layer of molten lava and nickel that surrounds the inner core of earth

12, the process by whichoceanic crust sinks beneath a deep ocean trench and back into the mantle at a convergent plate boundary

13. a section of the lithosphere that slowly moves oner the atmosphere carrying pieces of continental and oceanic crust

15. a deep valley that forms where two plates move apart

18. a dense spear of solid iron and nickel at the center of the earth
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