| A | B |
|---|
| asthenosphere | plasticlike layer of Earth's surface below the lithosphere |
| convection current | cycle of heating, rising, cooling and sinking |
| plate tectonics | theory that states that Earth's crust and upper mantle are broken into sections, which move around on a special layer of the mantle |
| subduction zone | area where an oceanic plate goes down into the mantle |
| transform boundary | plate boundary that occurs when two plates slide past one another |
| convergent boundary | place where two plates move together |
| lithosphere | rigid layer of Earth's surface made up of the crust and part of the mantle |
| magnetometer | sensing device that detects magnetic fields, helping to confirm seafloor spreading |
| Pangaea | one large landmass hypothesized to have broken apart about 200 million years ago into continents |
| continental drift | hypothesis that the continents have moved slowly to their current locations |
| divergent boundary | boundary between two plates that are moving apart |
| plates | section of Earth's crust and upper mantle |
| mantle | largest layer of Earth's surface, composed mostly of silicon, oxygen, magnesium, and iron |
| crust | outermost layer of Earth's surface |
