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Relative Dating
Geologic Time Part 1
Term | Definition |
---|---|
Uniformitarianism | The idea that forces working on our planet today worked on or planet in the past in the same manner |
Relative Dating | Determination of the age of a rock or event in relation to the ages of other rocks or events |
Principle Of Superposition | Basis for relative dating and the idea that the bottom layer is the oldest and each over lying layer gets younger |
Original Horizontality | Idea that sedimentary and igneous rocks are deposited in parallel layers to Earth's surface |
Extrusions | Molten rock flows onto the surface |
Intrusions | Molten rock squeezes into preexisting rock layers (Younger then the rocks that they crosscut, Exception to the principle of superposition) |
Contact Metamorphism | Temperature induced change of preexisting rocks along an intrusive |
Faults | A crack in the bedrock where movement has occured |
Folds | When thrusting rock layers cause preexisting rock layers to overturn |
Correlation | The process of showing that rocks or geologic events from different places are the same or similar age |
Correlating Rocks | Similarities in rock, rock sequence, mineral composition, color, and fossils |
Fossils | Remains or evidence of former living things (Examples: bones, shells, footprints, and organic compounds [DNA]) |
Index Fossils | Fossil used to define and identify geologic periods (good index fossil is an organism that existed over a large geographic area and that have existed over a short period of time) |
Geologic Time Markers | Deposits spread over large areas that represent a specific date (Examples: volcanic ash deposits and meteorites impacts) |