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14 Cards in this Set
- Front
- Back
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The four principle eras of the geologic time scale (from the earliest to the most recent)
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1. Precambrian
2. Paleozoic 3. Mesozoic 4. Cenzoic |
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Precambrian Life Characteristics
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Spans from the formation of the earth to the evolution of macroscopic hard shelled animals
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Paleozoic Life Characteristics
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Spans from the appearance of soft shelled animals to the start of the age of the reptiles and modern plants
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Paleozoic Land Characteristics
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Started shortly after the breakup of a supercontinent at the end of an ice age, ended as the continents formed Pangea
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Mesozoic Life Characteristics
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The age of the reptiles
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Mesozoic Land Characteristics
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Continents shifted from their current state through continental drift, allowing speciation and other evolutionary developments to take place
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Cenozoic Life Characteristics
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Began with the demise of the last non-avian dinosaurs, and is currently ongoing
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Cenozoic Land Characteristics
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The continents moved into their current positions
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Disconformity
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The contact representing missing rock strata separates beds that are parallel to one another
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Angular Unconformity
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A contact in which younger strata overlie an erosion surface on tilted or folded layered bedrock
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Nonconformity
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A contact in which an erosion surface on plutonic or metamorphic rock has been covered by younger sedimentary or volcanic rock
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Requirements for Radiometric Dating
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1) Igneous or metamorphic rock
2) Decay rate of isotope 3) Accurate measurement of % parent within the mineral |
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Steps for Radiometric Dating
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1) Determine the ratio of parent isotopes to daughter isotopes
2) Using the ratio, determine the number of half lives elapsed 3) For the Parent-Daughter pair, find the time for each half life 4) Multiple the number of half lives elapsed by the time for each half life |
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Rules of Geologic Time
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1) Superposition - newest on top
2) Cross cutting relations - faults, folds, or intrusions are younger than the rocks, faults, folds, or intrusions they cut 3) Inclusions - are older than their host rocks |
