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Geological History
Unit 6 vocab
| Term | Definition |
|---|---|
| Fossil | A remain, imprint, or trace of prehistoric life |
| Index Fossil | Remains of once-living things from millions of years ago |
| Permineralized Remains | Fossils filled with minerals from groundwater |
| Molds and Casts | A type of body fossil |
| Original Remains | Still-existing fossils of prehistoric animals |
| Trace Fossils | Fossil consisting of imprint or track of an organism |
| Relative Age | Age of something compared with other things |
| Superposition | Order of sedimentary strata |
| Horizontality | The layers in the soil |
| Absolute Age | Age in years of a rock or other object |
| Half-life | The time taken for half the atoms in an isotope to decay |
| Isotopes | Amounts of the same elements with different numbers of neutrons |
| Radioactive Decay | Process where some isotopes break into smaller isotopes |
| Geological Time | The division in Earth's history |
| Eon | The longest subdivision in geological time |
| Era | Subdivided into periods |
| Period | Characterized by types of life that existed worldwide |
| Epoch | Characterized by differences in life-forms |
| Pangaea | The world when dinosaurs roamed the Earth |
| Trilobite | Organism with 3-lobed exoskeleton |
| Precambrian | Longest part of Earth's history |
| Mesozoic Era | The time of the dinosaurs |
| Cenozoic Era | The time of the first humans |