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Science test#5
| Question | Answer |
|---|---|
| Relative Age | Age of a rock compaired to other rock layers. |
| Fossile | Zny trace, or imprint or remains of a liveing thing preserved in Earth's crust. |
| Half- life | The time it takes for half of the mass of a radioactive element to decay into another element |
| Absolute Age | Age of a rock by compairing the original element amount of decay products present |
| Era | Long streaches of time to mesure Earht's geogolical history |
| Peroid | One of the primary divisions of a geogolical era. |
| Original Horizontiality | Sedimentary rock forms in horizontial layers. |
| Superposition | In a serious of rock layers, the bottom layer is the oldest and the top is the youngest. |
| Geologic comomn | Listings of earth's rock layers from oldest to youngest |
| Cast | Organisms covered by sediment soonn after death, soft parts decay and hard parts (bones, teeth) last long enough to be preserved. |
| Imprint | Buried or squeezed between layers and fluids removed. |
| Petrifited | Buried organisms trapped in sediment. |
| Index fossile | Live for a short peroid of time widespread over earth and evove rapidly. |
| Trilobites | Sea animals. |
| Precambrian | Began 4.6 billion years ago earths formation earliest life formed in sea multi- cellur, marine organisms few fossils |
| Paleozic | 600 Million years ago life abundunt sea and land insects amphibans trilobites fish reptiles farests. |
| Mesozic | 245 Million years ago dinosaurs mammles birds flowering plants pangea began to break apart climats milder |
| Cenozoic | 65 Million years ago mammles dominate humans appear about 2 million years ago. |
| Peroid | Part of era associated with major changes in earth's crust. |
| Geogoligical timescale | major events and life forms on earth during each era. |