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Mod. D Unit 1 Less 1
Mod D Unit 1 Lesson 1 The Fossil Record
| Term | Definition |
|---|---|
| Fossil | the remains or traces of once-living organisms. |
| Sedimentary Rock | types of rock that are formed by the deposition and subsequent cementation of that material at the Earth's surface and within bodies of water. |
| Law of Superposition | states that in a sequence of undisturbed sedimentary rocks, the oldest layers are at the bottom and the youngest ones are at the top. |
| Geologic Columns | an ordered arrangement of rock layers that is based on the relative ages of the rocks, with the oldest rocks at the bottom of the column. |
| Index Fossil | a widely distributed fossil, of narrow range in time, regarded as characteristic of a given geological formation, used especially in determining the age of related formations. |
| Radiometric Dating | the method of finding the absolute age of rock based on comparing the amounts of unstable, radioactive particles to stable particles in a sample. |
| Geologic Timescale | divides Earth’s history into intervals of time defined by major events or changes on Earth. |
| Fossil Record | the collection of all known fossils and their placement in order from earliest to most recent. |
| Extinction | when all members of a species die out. |