Quaternary
The Quaternary (/kwəˈtɜːrnəri, ˈkwɒtərnɛri/ kwə-TUR-nə-ree, KWOT-ər-nerr-ee) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ago to the present. As of 2023, the Quaternary Period is divided into two epochs: the Pleistocene (2.58 million years ago to 11.7 thousand years ago) and the Holocene (11.7 thousand years ago to today); a third epoch, the Anthropocene, has recently been proposed, but it is not officially recognised by the ICS.
| Quaternary | |||||||||
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A map of the world as it appeared during the Pleistocene epoch, c. 1 Ma | |||||||||
| Chronology | |||||||||
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| Etymology | |||||||||
| Name formality | Formal | ||||||||
| Usage information | |||||||||
| Celestial body | Earth | ||||||||
| Regional usage | Global (ICS) | ||||||||
| Time scale(s) used | ICS Time Scale | ||||||||
| Definition | |||||||||
| Chronological unit | Period | ||||||||
| Stratigraphic unit | System | ||||||||
| Time span formality | Formal | ||||||||
| Lower boundary definition |
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| Lower boundary GSSP | Monte San Nicola Section, Gela, Sicily, Italy 37.1469°N 14.2035°E | ||||||||
| Lower GSSP ratified | 2009 (as base of Quaternary and Pleistocene) | ||||||||
| Upper boundary definition | Present day | ||||||||
| Upper boundary GSSP | N/A | ||||||||
| Upper GSSP ratified | N/A | ||||||||
| Atmospheric and climatic data | |||||||||
| Mean atmospheric O2 content | c. 20.8 vol % (104 % of modern) | ||||||||
| Mean atmospheric CO2 content | c. 250 ppm (1 times pre-industrial) | ||||||||
| Mean surface temperature | c. 14 °C (0 °C above modern) | ||||||||
The Quaternary Period is typically defined by the cyclic growth and decay of continental ice sheets related to the Milankovitch cycles and the associated climate and environmental changes that they caused.