| A | B |
|---|
| plate boundary | fault |
| crust | outer layer of the Earth |
| mantle | thickest layer of the Earth |
| outer core | liquid center of the Earth |
| inner core | solid iron center of the Earth |
| 12 | number of major plates |
| Plate Tectonics theory | crust is broken into 12 plates that constantly move |
| continental drift theory | the continents have moved and continue to move today |
| Pangaea | supercontinent |
| convergent boundary | plates come together |
| divergent boundary | plates pull apart |
| transform boundary | plates slide past each other |
| magma | melted rock below the surface |
| lava | melted rock above the surface |
| cinder cone | volcano with steep sides; explodes ash and cinders |
| shield volcano | large, gently sloped volcano that has quiet eruptions |
| composite cone | large, steep sided volcano that can have both quiet and violent eruptions |
| earthquake | ground shakes violently due to plate movement |
| focus | place where an earthquake starts |
| epicenter | point on Earth's surface directly above where an earthquake starts |
| Richter scale | used to measure the strength of an earthquake |
| Ring of Fire | area around the Pacific Ocean where most volcanoes and earthquakes occur |
| the age of the Earth | 4.6 billion years |
| Precambrian Era | longest and oldest geologic time period |
| Cenozoic Era | current and shortest geologic time period |
