Using the graph, determine the number of half-lives elapsed for each sample. The discordia is often interpreted by extrapolating both ends to intersect the Concordia. By allowing the establishment of geological timescales, it provides a significant source of information about the ages of fossils and the deduced rates of evolutionary change. Since the mineral troilite contains no U, all of the Pb present in the troilite is the Pb originally present, and none of it has been produced by U decay. Vetter; Donald W. If this happens, then the date obtained will be older than the date at which the magma erupted. Of the origin of radiometric parent substances for the stable outcome of radioactive-parent:
Discordant dates will not fall on the Concordia curve.
After one half-life will decay occurs, and daughter product; be calculated. In the century since then the techniques have been greatly improved and expanded. Brent Radiometric Dating and the Geological Time Scale: Rubidium—strontium dating. A relatively short-range dating technique is based on the decay of uranium into thorium, a substance with a half-life of about 80, years.