To determine a sequence of events in history, relative dating methods can be utilized. To define stratigraphic correlations, stable isotopes use changes in isotopic ratios of a particular element. This works on the belief that proportions of certain isotopes in biogenic materials change over time in relation to changing geological and paleoenvironmental conditions. Still, the main signal is frequently masked by diagenetic alteration which may also alter the isotopic ratios. Separating primary and secondary parts of measured isotopic ratios can be a debated topic on its own. Although many elements have been used in isotopic stratigraphy, isotopes of oxygen, carbon and strontium are largely widespread. Actlabs can determine isotopic ratios in a variety of sample media including: rock, core, soils, and water samples.