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Geologic Time
| Term | Definition |
|---|---|
| Law of superposition | undisturbed layers get younger as you go up |
| principle of original horizontality | all beds originally deposited in water form close to horizontally |
| principle of cross-cutting relationship | when a fault cuts through rock, the rock is younger |
| inclusions | pieces of one rock unit contained within another |
| conformable | strata sequence that is undisturbed |
| unconformities | gaps in geologic time that indicate erosion, deformation |
| disconformities | large gap in geologic time due to processes of erosion |
| angular unconformities | younger strata overlie an erosion surface on tilted or folded rock |
| nonconformities | igneous or metamorphic magma chamber intrudes, then erosion erodes |
| petrification | turn to stone (LOOKS LIKE WOOD) |
| replacement | cell membrane are removed and replaced with mineral matter |
| mold | reflects the shape and surface marking |
| cast | a mold that is filled in with mineral matter and solidified |
| carbonization | carbon film left behind after organism decay (PLANT) |
| impression | carbonization process, carbon lost and replica of surface |
| amber | resin from trees, insects are preserved (WHOLE ORGANISM) |
| tracks | animal footprints in sediment later solidified |
| coprolites | fossil poo and stomach contents that were preserved |
| gastroliths | polished stomach stones |
| burrows | tubes in sediment, wood, or rock made by an animal |
| rock and fossil correlation | matching of rock layers from one location at the same time to another location |
| principle of fossil succession | older rock contain fossils that are increasingly different from modern species |
| fossil assemblage | several different species found together in a specific rock unit |
| index fossil | well defend morphological characteristics (short-lived species and widespread distribution |
| radiometric dating | calculating the absolute ages of rock and minerals that contain radioactive isotoped |
| alpha emission | atomic #= -2 mass # -4 |
| beta emission | atomic #= +1 mass # unchanged |
| electron capture | atomic # = -1 mass #= unchanged |
| half-life | time required for half of the nuclei in a sample to decay |
| radiocarbon dating | date recent events (carbon -14) |
| half life of carbon014 | 5730 yrs |
| half life of uranium-238 | 4.5billion years |
| numerical dating | actual number of yrs |
| how do geologists numerically date rocks | radioactive decay |
| relative dating | events in their proper sequence |
| biggest era | paleozoic |
| present era | cenozoic |
| present eon | phanerozoic |
| present epoch | holocene |
| present period | quaterary |
| what eon means visible life | phanerozoic |
| uniformitarianism | the physical chemical and biological laws that operate today have also operated in the geologic past (long history of earth) |
| catastrophism | earth's landscape has been developed by worldwide disasters (over a short span)(catastrophism does not require assumptions of long timelines) |
Created by:
miabegic2
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