Geologic time rock dating

The geologic record in stratigraphy, paleontology and other natural sciences refers to the entirety of the layers of rock strata — deposits laid down by volcanism or by deposition of sediment derived from weathering detritus (clays, sands etc.) including all its fossil content and the information it yields about the history of the Earth: its past climate, geography, geology and the evolution of life on its surface.

Also, petroleum geologists are mainly interested in rocks from the Mesozoic and Paleozoic Eras.As time passes, the "parent" radioactive elements change at a regular rate into non-radioactive "daughter" elements.Thus, the older a rock is, the larger the number of daughter elements and the smaller the number of parent elements are found in the rock.A common "parent-daughter" combination that geologists use is radioactive uranium and non-radioactive lead.As shown in the diagram above, uranium is trapped in a newly formed rock.This is because almost all of the oil and gas found so far is contained within these rocks.


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