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Ch 6- 8th grade sci
The Rock and Fossil Record
| Question | Answer |
|---|---|
| Uniformitarianism | A principle that states that geologic processes that occurred in the past can be explained by current geologic process |
| Catastrophism | A principle that states that geologic change occurs suddenly |
| Paleontology | The scientific study of fossils |
| Relative dating | Any method of determining whether an event or object is older or younger than other events or objects |
| Superposition | A principle that states that younger rocks lie above older rocks if the layers have not been disturbed |
| Geologic Column | An arrangement of rock layers in which the oldest rocks are at the bottom |
| Unconformity | A break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time |
| Absolute dating | Any method of measuring the age of an event or object in years |
| Isotope | An atom that has the same number of protons (or the same atomic number) as other atoms of the same element do but that has a different number of neutrons (and thus a different atomic mass) |
| Radioactive decay | The process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element |
| Radiometric Dating | A method of determining the age of an object by estimating the relative percentages of a radioactive (parent) isotope and a stable (daughter) isotope |
| Half-life | The time needed for half of a sample of a radioactive substance to undergo radioactive decay |
| Fossil | The remains of physical evidence of an organism preserved by geological processes |
| Trace fossil | A fossilized mark that is formed in soft sediment by the movement of an animal |
| Mold | A mark or cavity made in a sedimentary surface by a shell or other body |
| Cast | A type of fossil that forms when sediments fill in the cavity left by a decomposed organism |
| Index fossil | A fossil that is found in the rock layers of only one geologic age and that is used to establish the age of the rock layers |
| Geologic Time Scale | The standard method used to divide the Earth's long natural history into manageable parts |
| Eon | The largest division of geologic time |
| Era | A unit of geologic time that includes two or more periods |
| Period | A unit of geologic time into which eras are divided |
| Epoch | A subdivision of a geologic period |
| Extinction | The death of every member of a species |
Created by:
hsdragon
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