Plate Tectonics

2. Who made the hypothesis of continents plowed across the ocean floors?
4. the ocean floor plunging into deep under water canyons called
6. the hypothesis that the continents slowly moved across Earth's surface.
8. What often occur along the transform boundaries?
10. the ocean floor is renewed every
12. is a place where two plates slip past each other, moving in opposite directions
13. adds new material to the ocean floor.
16. where two plates move apart, or diverge
17. a deep valley
20. a fernlike plant that lived 250 million years ago.
21. the process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle is called

1. an undersea mountain chain where new ocean floor is produced.
3. in a process taking tens of millions of years, part of the sinks back into the mantle at deep ocean trenches
5. where two plates come together, or converge is called a
7. breaks in the earths crust where rocks have slipped past each other to form along these boundaries
9. is a well tested concept that explains a wide range of observations
11. pieces of the earths lithosphere are in a slow, constant motion, driven by convection currents in the mantle.
14. The continents drifting together to form the supercontinent
15. the lithosphere broken into separate sections is called
18. Any Trace of an ancient organism that has been preserved in rock.
19. a device that bounces sound waves off underwater objects and then records the echoes of these soundwaves.