Radioactive dating example problems
Other creationists have focused on instances in which radiometric dating seems to yield incorrect results.In most instances, these efforts are flawed because the authors have misunderstood or misrepresented the data they attempt to analyze (for example, Woodmorappe 1979; Morris HM 1985; Morris JD 1994).Only rarely does a creationist actually find an incorrect radiometric result (Austin 1996; Rugg and Austin 1998) that has not already been revealed and discussed in the scientific literature.The creationist approach of focusing on examples where radiometric dating yields incorrect results is a curious one for two reasons.Not only that, they have to show the flaws in those dating studies that provide independent corroborative evidence that radiometric methods work.This is a tall order and the creationists have made no progress so far.It will probably fail, but what would a reasonable person conclude from that? All they indicate is that the methods are not infallible.Those of us who have developed and used dating techniques to solve scientific problems are well aware that the systems are not perfect; we ourselves have provided numerous examples of instances in which the techniques fail.
The Manson Meteorite Impact and the Pierre Shale In the Cretaceous Period, a large meteorite struck the earth at a location near the present town of Manson, Iowa.The heat of the impact melted some of the feldspar crystals in the granitic rocks of the impact zone, thereby resetting their internal radiometric clocks.These melted crystals, and therefore the impact, have been dated by the 40Ar/39Ar method at 74.1 Ma (million years; Izett and others 1998), but that is not the whole story by a long shot.The Pierre Shale, which is divided into identifiable sedimentary beds called members, also contains abundant fossils of numerous species of ammonites, ancestors of the chambered nautilus.
The fossils, when combined with geologic mapping, allow the various exposed sections of the Pierre Shale to be pieced together in their proper relative positions to form a complete composite section (Figure 1).
The Pierre Shale also contains volcanic ash that was erupted from volcanoes and then fell into the sea, where it was preserved as thin beds.