| A | B |
|---|
| asthenosphere | Zone of partially melted rock in upper mantle |
| convergent boundary | Plates collide along it |
| core | innermost layer of Earth |
| crust | outermost layer of Earth |
| divergent boundary | plates move away from each other along it |
| earthquake | sudden movement of rocks in Earth's crust |
| epicenter | int on Earth's surface directly above focus |
| focus | point in Earth's crust where an earthquake starts |
| lithosphere | layer that includes crust and upper mantle |
| mantle | layer directly above the core |
| mid-ocean ridge | chain of mountains through the oceans |
| P wave | pus-pull or back-and-forth wave caused by earthquakes |
| plate tectonics | theory of plate movements |
| Richter scale | scale that measures amount of earthquake energy |
| rift | forms where two plates move apart |
| S wave | up-and-down, slower wave in Earth's crust |
| sea-floor spreading | proces that forms new sea floor along rift |
| surface wave | earthquate wave that makes the ground rol and sway |
| transform fault boundary | plates grind past each other along it |
| volcano | mountain that forms around an opening in Earth's crust |
