| A | B |
|---|
| Cinder cone | Small volcano with steep sides and explosive eruptions made of ash and rock |
| Composite volcano | Tall volcano; formed from quiet lava flows that alternate with eruptions of rock and ash |
| Continental drift | Theory that the major landmasses of the Earth move |
| Convection current | Circular motion of a gas or liquid as it heats |
| Core | Dense center of the Earth made of solid and melted metals |
| Crust | Outer layer of the Earth |
| Folding | Bending of rock layers that are squeezed together |
| Mantle | Layer of the Earth that surrounds the core |
| Normal Fault | Break in the crust in which the overhanging block of rock has slid down |
| Pangaea | Single landmass from which Alfred Wegener thought the continents separated millions of years ago |
| Plate | Large section of the Earth's crust that moves |
| Plate tectonics | Theory that the Earth's surface is made of large sections of crust that move |
| Reverse fault | Break in the crust in which the overhanging block of rock has been raised |
| Sea-floor spreading | theory that the ocean floor spreads apart as new crust is formed at mid-ocean ridges |
| Shield-volcano | Low broad volcano with a wide crater; formed from thin layers of lava |
| Strike-slip fault | Break in the crust in which the blocks of rock move horizontally past each other |
| Vent | Round opening through which magma reaches the surface of the Earth |
| Volcano | Mountain that develops where magma pushes up through the Earth's surface |
| Aa | Cool, slow moving lava that is rough and jagged |
| Pahoehoe | Lava with a smooth ropelike surface |
| Ash | Smallest pieces of pyroclastic material |
| Lapilli | Medium sized pyroclastic material |
| Bombs | Largest pieces of pyroclastic material |
