Geochronology is the scientific study of the age of the Earth, and the temporal sequence of events related to the formation of the planet and the history of life on Earth. The word is derived from Geo meaning Earth, and chronology, which is the study of time, or a record of events in the order of their occurrence (timeline). It is from this field of study that fossils and artifacts are dated based on the perceived age of the geological layers in which they are located. Geologists determine the age of rocks, fossils, and sediments using a variety of methods including relative and absolute dating.
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