Then, by assessing the isotope concentrations of rubidium and strontium, scientists can back-calculate to determine when the rock was formed.
The three isotopes mentioned can be used for dating rock formations and meteorites; the method typically works best on igneous rocks. The data from radioisotope analysis tends to be somewhat scattered.
Among the best-known techniques are radiocarbon dating, potassium-argon dating and uranium-lead dating.
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.
But, as the NC State study suggests, that final figure might not be taking other variables into account.
For one, the atoms of different elements will diffuse through a material at different rates due to a process known as differential mass diffusion.
By evaluating the concentrations of all of these isotopes in a rock sample, scientists can determine what its original make-up of strontium and rubidium were.
By calculating the ratios of rubidium-87 to strontium-86, and strontium-86 to strontium-87, a graph called an isochron is created, which scientists can then use to determine the age of a sample.
The process works best on igneous rocks, and has been used to study Earthly and lunar formations for decades.
However, problems remain in the interpretation of the measured Pb isotopic ratios to transform them into ages.
Among them is the presence of non-radiogenic Pb of unknown composition, often referred to as common or initial Pb.