EAS100 Lecture Notes - Lecture 10: Radiometric Dating, Unconformity, Deep Time
28 Sep 2018
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Eas 100 lecture 10 sedimentary and metamorphic rock. We can determine relative age by using stratigraphic principles and cross-cutting relationships. This is the simple principle that a geologic feature must be older than any other feature that cuts through it. Ex: if we see igneous rock cutting through another rock, we know the igneous rock came after, since the first rock had to pre-exist. Cross-cutting also works with fault lines, in that it must be younger than the rocks that it offsets. The only way we can determine exact ages of rocks are is by using radiometric dating/isotopic dating. ***it"s important to note, that radiometric dating can only be used on igneous and metamorphic rock! Igneous rock must cool to form at the exact same time, and because metamorphic rock must undergo a change, we can find the date of metamorphosis.
