13.07.2015 Views

Time, Cratons, and Voyageurs NP

Time, Cratons, and Voyageurs NP

Time, Cratons, and Voyageurs NP

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• Twoaspectsoftime:Geologic<strong>Time</strong>– Relativetime(oldervs.younger),arrangementintoasequence.Geologically,mostlybasedonsedimentaryrocks.– Absolutetime(quantitative),specificationofduration.Geologically,mostlybasedonigneousrocks.• Thegeologictimescalewasfirstdevelopedusingtheprinciplesofstratigraphy<strong>and</strong>faunalsuccession,thetwobasesofrelativedating.Absolutedatingbecamepossiblewiththelaterunderst<strong>and</strong>ingofspontaneousradioactivedecay.

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