Term
| Difference between geochronologic units and chronostratigraphic units |
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Definition
geochronologic:describe units of time (period)
chronostratigraphic: a stratigraphic method that interprets geologic history by determining age and time sequences within the rock units by examining the rock |
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Term
| What criteria creates the best index fossils? |
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Definition
relatively short temporal range, abundantly found worldwide, distinct morphology, rapid evolution
ammonite
graptolites |
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Term
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Definition
| uses radiogenic isotopes to date rocks. these isotopes break down at constant rates from parent to daughter. by measuring the amount of both, we can use the ratio to determine the number of half lives and the date of the rock |
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Term
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Definition
| sea level rises relative to land. rocks take a fining upward sequence. sand -> shale-> limestone |
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Term
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Definition
| sea level falls relative to land. rocks take a coarsening upward sequence limestone -> shale -> sand |
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Term
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Definition
| range of time in which a species or genus existed |
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Term
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Definition
| biozones recognized by the overlapping of several taxa ranges |
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Term
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Definition
1 correlate rocks
2 study past climate
3 study past environmental changes |
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Term
| absolute time vs relative time |
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Definition
absolute: assigning numerical ages
relative: putting events in chronological order |
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Term
| cross cutting relationship |
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Definition
| the rock doing the 'cutting' is younger than the strata it is cutting through but older than the rocks on top of it. |
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