Plate Tectonics

2. most layer of earths surface
5. layer of earths surface, composed mostly of silicon, oxygen, magnesium, and iron
7. ridges/where new ocean crust is formed
9. sea trenches/where ocean crust is destroyed
10. magma forced upward mantle at mid-ocean ridges produce seafloor
12. boundary/place where two plates move together
13. tectonics/theory that states that earths crust and upper mantle are broken into sections, which move around on a special layer of the mantle
14. large landmass hypothesized to have broken apart about 200 million years ago into continents
15. layer of earths surface made up of the crust and a part of the upper mantle
16. people to consider the moving of landmasses
17. rate that south america is moving away from Africa
19. current/cycle of heating, rising, cooling, and sinking

1. valley/long, narrow depression
2. drift/hypothesis that the continents have moved slowly to their current locations
3. wegner/his hypothesis was the continental drift
4. the earth/pangaea means
6. layer of earth's surface below the lithosphere
8. boundary/boundary between two plates that are moving apart
11. boundary/plate boundary that occurs when two plates slide past one another
13. of earths crust and upper mantle
18. Hess/proved Alferd Wegners hypothesis