| A | B |
|---|
| core | The central portion of the earth, believed to be composed mainly of iron & nickel in a molten state. |
| mantle | The portion of the earth, between the crust and core. |
| crust | The outer layer of the earth, about 22 miles deep under the continents and 6 miles deep under the oceans. |
| sedimentary rock | Rock that has been formed through the deposition & solidification of sediment. These are often deposited in layers, and frequently contain fossils. |
| igneous rock | Rock formed by the solidification of molten magma. |
| metamorphic rock | Rock that was once one form of rock but has changed to another under the influence of heat and/or pressure. |
| weathering | Various mechanical and chemical processes that cause exposed rock to decompose. |
| stalactite | A deposit, usually of calcium carbonate, shaped like an icicle, hanging from the roof of a cave. |
| stalagmite | A deposit, usually of calcium carbonate, resembling an inverted stalactite, formed on the floor of a cave. |
| geology | The science that deals with the dynamics and physical history of the earth. |
