The good dates are confirmed using at least two different methods, ideally involving multiple independent labs for each method to cross-check results.
Sometimes only one method is possible, reducing the confidence researchers have in the results. “They’re based on ‘it’s that old because I say so,’ a popular approach by some of my older colleagues,” says Shea, laughing, “though I find I like it myself as I get more gray hair.” Kidding aside, dating a find is crucial for understanding its significance and relation to other fossils or artifacts.
Methods of dating rocks Absolute dating involves determining a rock’s actual age as a number of years, whereas relative dating methods provide an estimate of the age of a rock by comparing it to rocks of a known age The Geological Time Scale has been created by combining both absolute and relative dating methods.
The scholar most associated with the rules of stratigraphy (or law of superposition) is probably the geologist Charles Lyell.As minerals crystallise in igneous and metamorphic rocks they trap certain isotopes in their crystal structure that begin to decay radioactively as soon as the mineral forms.These radioactive isotopes are parent isotopes, which decay slowly to daughter isotopes, changing the rock’s isotopic character.Archaeological scientists have two primary ways of telling the age of artefacts and the sites from which they came: relative dating and absolute dating.Relative dating in archaeology presumes the age of an artefact in relation and by comparison, to other objects found in its vicinity.Methods fall into one of two categories: relative or absolute.