| A | B |
|---|
| crust | the outermost, thinnest layer |
| mantle | largest layer, contains convection currents |
| inner core | composed of solid nickel and iron, densest layer |
| outer core | composed of liquid nickel and iron, only liquid layer |
| Continental Drift | the hypothesis that the continents moved apart from a single large supercontinent called Pangaea |
| convergent boundary | plates move toward each other, causes mountain ranges |
| divergent boundary | plates move apart from each other |
| transform fault boundary | plates slide past each other |
| subduction | a denser plate sinks below a less dense plate |
