High Quality Content by WIKIPEDIA articles! The geologic time scale is a system of chronological measurement that relates stratigraphy to time, and is used by geologists, paleontologists, and other earth scientists to describe the timing and relationships between events that have occurred throughout Earth`s history. The table of geologic time spans presented here agrees with the dates and nomenclature set forth by the International Commission on Stratigraphy, and uses the standard color codes of the United States Geological Survey.