Plate Tectonics

3. Measurement of angular distance on the Earth east or west of the prime meridian
4. Melted rock beneath Earth's surface
5. plate boundaries Where two tectonic plates move away from each other
7. currents Movement within hot fluids, when the heat source is on the bottom, such as in a boiling pot of soup on the stove
9. Opening in Earth's crust where melted rock reaches Earth's surface
10. ("all land") the single huge supercontinent that existed 245 million years ago, when all of Earth's continents were joined together
11. scale Numerical description of the size of seismic waves produced by an earthquake
12. The rigid, brittle layer made up of the crust and the uppermost part of the mantle. It is broken up into pieces called tectonic plates
17. plates Large pieces of the lithosphere that slowly move on top of the asthenosphere
18. Imaginary east-west line that circles Earth halfway between geographic poles

1. The process by which one tectonic plate sinks below another, returning to the mantle, where the rock is re-melted
2. wave Vibration produced by an earthquake
6. convection Convection currents in the mantle that occur because hot rock in the lower part of the mantle is less dense and rises, and cooler rock in the upper part of the mantle cools, becomes more dense, and sinks
7. drift The theory that all of Earth's continents were once joined together into a single large landmass, and then moved apart, forming the continents we see today
8. plate boundaries Where two tectonic plates move toward each other
12. Measurement of angular distance on the Earth north or south of the equator
13. plate boundary Where two tectonic plates slip past each other, moving in opposite direction
14. Instrument that measures and records seismic waves
15. Point on Earth's surface directly above an earthquakes focus
16. The true location of an earthquake and source of seismic waves