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Mod. D Unit 1 Less 1
Mod D Unit 1 Lesson 1 The Fossil Record
Term | Definition |
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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. |