chronostratigraphic time scale

The chronostratigraphic time scale is a system used in geology to organize Earth's history based on rock strata and the fossils they contain. It divides time into named units like eons, eras, periods, and epochs. Initially, relative ages were determined by the position of rock layers (superposition) and the types of fossils found within them, a principle known as faunal succession.123

With advancements like radiometric dating, which measures the decay of radioactive atoms, these relative ages have been numerically quantified. This allows scientists to assign specific numerical ages to boundaries within the chronostratigraphic scale, providing a more precise calendar for Earth's history. This scale is crucial for understanding the sequence of geologic events and the evolution of life.4215