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33 Cards in this Set
- Front
- Back
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catastrophism
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the concept that earth was shaped by catastrophic events of short-term nature
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uniformitarianism
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the concept that the processes that have shaped earth in the geologic past are essentially the same as those operating today
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relative dating
principle of fossil succession radiometric dating |
what are the three types of dating?
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relative dating
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rocks placed in their proper sequence or order. only the chronological order of events is determined
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1. principle of original horizontality
2. law of superposition 3. principle of cross-cutting relationships 4. inclusions 5. unconformities |
what are the 5 principles of relative dating?
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original horizontality
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layers of sediments are generally deposited in a horizontal or nearly horizontal position
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superposition
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in any undeformed sequence of sedimentary rocks, each bed is older than the layers above and younger than the layers below
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cross-cutting
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a principle of relative dating. a rock or fault is younger than any rock (or fault) through which it cuts
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inclusions
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a piece of one rock unit contained within another. inclusions are used in relative dating. the rock mass adjacent to the one containing the inclusion must have been there first in order to provide the fragment
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unconformity
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a surface that represents a break in the rock record, caused by erosion or nondeposition
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conformable
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layers of rock that were deposited without interruption
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disconformity
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a type of unconformity in which the beds above and below are parallel
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disconformity
angular unconformity nonconformity |
three different types of unconformities?
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paleontology
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the study of fossils
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fossil
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races or remains of an ancient creature primarily found in sedimentary rocks
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petrification
cast mold carbonization amber trace fossils |
what are the six types of fossilization?
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petrification
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turned into stone
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fossil succession
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fossil organisms that succeed one another in a definite and determinable order, and any time period can be recognized by its fossil content
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index fossils
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a fossil that is associated with a particular span of geologic time
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correlation
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establishing the equivelance of rocks of similar age in different areas
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relative dating
fossil succession radiometric dating |
three things used to correlate rocks?
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radioactivity
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the spontaneous decay of certain unstable atomic nuclei
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half-life
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the time required for one half of the atoms of a radioactive substance to decay (parent isotope, daughter product)
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parent isotope (original isotope before decay)
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unstable radioactive isotope
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daughter product (stable isotope)
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an isotope resulting from radioactive decay
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radiometric dating
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the procedure of calculating the absolute ages of rocks and minerals that contain radioactive isotopes
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radiocarbon dating
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(carbon 14) the radioactive isotope of carbon, which is produced continuously in the atmosphere and is used in dating events from the very recent geologic past (the last few tens of thousands of years)
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geologic time scale
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the division of earth history into blocks of time--eons, eras, periods, and epochs. the time scale was created using relative dating principles
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1. paleozoic
2. mesozoic 3. cenozoic |
phanerozoic eon has 3 eras
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paleozoic
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ancient life
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mesozoic
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middle life
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cenozoic
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recent life
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periods
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a basic unit of the geologic calendar that is a subdivision of an era. periods may be divided into smaller units called epochs
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