Sedimentary rocks can be dated using radioactive carbon, but because carbon decays relatively quickly, this only works for rocks younger than about 50 thousand years. Here, the symbol k is the radioactive decay constant, which has units of inverse time e. Alternatively, if several different minerals can be dated from the same sample and are assumed to be formed by the same event and were in equilibrium with the reservoir when they formed, they should form an isochron. The GPTS is divided into periods of normal polarity and reversed polarity. Once one reversal has been related to the GPTS, the numerical age of the entire sequence can be determined.
The principles of stratigraphy help us understand the relative age of rock layers.
20.6: The Kinetics of Radioactive Decay and Radiometric Dating
More questions. A record of the multiple episodes of reversals of the Earth's magnetic polarity that can be used to help determine the age of rocks half-life: Yahoo Answers. Geologists commonly use radiometric dating methods, based on the natural radioactive decay of certain elements such as potassium and carbon, as reliable clocks to date ancient events. This transformation may be accomplished in a number of different ways, including alpha decay emission of alpha particles and beta decay electron emission, positron emission, or electron capture. For instance, carbon has a half-life of 5, years.