| A | B |
|---|
| asthenosphere | zone of the earth's mantle that lies beneath the lithosphere |
| convergent boundary | place where two plates moving from different directions meet head-on |
| continental drift | the idea that continents move |
| convection | movement of a fluid because of density differences |
| convection current | circular pattern of hear in mantle; responsible for movement of the plates |
| density | ratio between the mass and the volume of a substance, found by dividing an object's mass by its volume |
| divergent boundary | place where two plates of lithosphere are moving apart and new lithosphere is formed |
| lithosphere | solid outer layer of Earth including both crust and upper mantle |
| magma | melted rock beneath's earth's surface |
| mid-ocean ridge | long chain of underwater mountains |
| Pangaea | name of the supercontinent thought to have split into the landmasses |
| plate | large moving section of lithosphere that contains continents and seafloor |
| plate techtonics | theory that crust is broken up into solid plates that move on top of the putty like asthenoshere |
| rift | deep valley which runs down the middle of a mid-ocean ridge |
| seafloor spreading | theory that seafloor crust forms at mid-ocean ridges and then spteads in opposite directions |
| subduction | pushing of the edge of one plate below the edge of another |
| transform boundary | place where two plates meet and slide past each other (sliding boundary) |
