[ep-uhk or, especially Brit., ee-pok]
epoch, unit of geologic time that is a subdivision of a period. The Pleistocene and Holocene epochs, for example, are divisions of the Quaternary period. Epoch is also used to describe a short length of geologic time during a special occurrence, such as the glacial epoch. See geology; Geologic Timescale (table).

Unit of geologic time during which a rock series is deposited. It is a subdivision of a geologic period. Additional distinctions can be made by adding relative time terms, such as early, middle, and late. The use of the term is usually restricted to divisions of the Tertiary and Quaternary periods.

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In periodization, epoch can refer to:

Proper noun


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