vocabulary: tectonic plates

7. boundary/moving away from each other
8. boundary/moving towards each other
9. supercontinent that included all current land masses, believed to have been in existence before the continents broke apart during the Triassic and Jurassic Periods.
11. currents/a current in a fluid that results from convection
12. plates/the two sub-layers of the earth's crust (lithosphere) that move, float, and sometimes fracture and whose interaction causes continental drift, earthquakes, volcanoes, mountains, and oceanic trenches.
13. boundary/slides past each other

1. sideways and downward movement of the edge of a plate of the earth's crust into the mantle beneath another plate
2. crust/thin part of earths crust that unlies the ocean basins
3. valley/a large elongated depression with steep walls formed by the downward displacement of a block of the earth's surface between nearly parallel faults or fault systems.
4. drift/the separation of the continents
5. upper layer of earths mantle
6. long, narrow ditch
10. crust/thick part of the earths crust
14. wegener/discovered the continental drift