Plate Tectonics

4. The layer more dense the the continental crust
7. When two plates move away from each other
10. When two plates collide head on with each other
12. The layer with the least density
13. The shape most volcanoes come in
14. Molten rock the erupts from volcanoes
16. The rigid outer part of the earth, consisting of the crust and upper mantle
18. Molten rock that is beneath the earths surface
19. Cooled lava
21. A vent in the earths surface where magma and gases erupt

1. When two plates slide past each other
2. The layer of the earth under the crust
3. Heat transfer in a gas/liquid by the rotation of currents from one region to another
5. Portion of motion of a tectonic plate that can be accounted for by its subduction
6. Happens when the force of two plates sliding past each other releases
8. A type of excavation or depression in the ground
9. An elevated region with a central valley on an ocean floor
11. Force proposed for plate motion in plate tectonics
15. Where most volcanoes and earthquakes happen
17. The downward movement of the edge of a plate of the earth's crust into the mantle
20. Usually caused by transform boundaries