| A | B |
|---|
| Uniformitarianism | theory that the Earth is changed by the same small forces that have changed it in the past |
| Catastrophism | theory that the Earth is changed by major events |
| Paleontology | the study of fossils |
| Relative Dating | comparing the age of two items |
| Absolute Dating | finding the exact age |
| Radiometric Dating | estimating the age based on the amounts of certain chemicals |
| unconformity | a disturbance in the rock layers |
| Geologic column | a theoretical section of the Earth's crust where all the layers intact |
| superposition | term describing a group of rock layers in order |
| petrifaction | process of an organism turning to stone |
| mold | a rock impression of an organism |
| cast | a rock copy of an organism |
| fossil | a petrified organism |
| trace fossil | a rock with evidence of an organism, i.e. nests, egg shells |
| extinction | when an organism no longer exists |
