| A | B |
|---|
| CRUST | hard, thin outside layer of Earth |
| MANTLE | thickest layer, composed of melted rock |
| OUTER CORE | liquid iron and other material layer that surrounds the solid inner core |
| INNER CORE | intermost layer of the earth, made of solid iron |
| LITHOSPHERE | crust and upper part of mantle |
| CONTINENTAL DRIFT | theory that at one time all the continents formed one large continent and slowly drifted apart |
| SEA FLOOR SPREADING | new crust being formed in the ocean pushing aside old crust |
| GEOLOGIST | a scientist who studies the Earth |
| ALFRED WEGENER | geologist who came up with theory of Continental Drift |
| SCIENTIFIC THEORY | well tested concept that explains observations |
| PLATE TECHTONICS | theory that Earth is divided into plates that float on the mantle |
| PLATE BOUNDARIES | areas where two plates meet |
