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fossils and unconfor
Term | Definition |
---|---|
Absolute Age | The exact age of a rock or fossils |
Angular unconformity | When there is movement of the earth that turns the rock layers at an angle. |
Anticline | An upward fold of rock |
Crosscutting | Intrusive magma or lava is always younger than the existing rock. |
Elastic limit | the amount of heat and pressure rock can withstand before breaking. |
Extrusion | Lava that hardens on the surface |
Folding | When heat and pressure bends a rock |
Fossils | The preserved remains or traces of an organism |
index fossils | Useful fossils that help determine the age of other fossils or rock layers. They must 1) have lived and died in a relatively short period of time and 2) They need to be widely distributed. |
Intrusion | Magma cooled and hardened into a mass of igneous rock. |
Lava | Flow from the mantle that is on top of the crust |
Law of Inclusion | When rock layers have bits of the rock layer below it, it must be younger than the one below it. |
Magma | Flow from the mantle that is inside the crust |
Relative Dating | Determining the relative age of rock layers or order of past geologic events |
Relative Age | The approximate age of a rock layer or fossil |
Syncline | A downward fold of rock |
Strata | Rock layers |
The Law of Superposition | In an undisturbed horizontal sequence of rocks, the oldest rock layers will be on the bottom. |
Unconformity | represent gaps in the geologic record; periods of time that are not represented by any rocks. |