Pleistocene

Pleistocene
2.58 – 0.0117 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
The world during the Last Glacial Period, 115,000–11,700 years Before Present (note: glaciers not shown, sea level and coastlines fluctuated throughout the period)
Chronology
−2.6 — – −2.4 — – −2.2 — – −2 — – −1.8 — – −1.6 — – −1.4 — – −1.2 — – −1 — – −0.8 — – −0.6 — – −0.4 — – −0.2 — – 0 — Cenozoic N Quaternary Pliocene Pleistocene   Gelasian Calabrian Chibanian "Late"             ← Holocene Subdivision of the Quaternary according to the ICS, as of 2021.[1][2] Vertical axis scale: millions of years ago.
Etymology
Name formality	Formal
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Definition
Chronological unit	Epoch
Stratigraphic unit	Series
Time span formality	Formal
Lower boundary definition	Base of magnetic polarity chronozone C2r (Matuyama). Extinction of the haptophytes Discoaster pentaradiatus and Discoaster surculus
Lower boundary GSSP	Monte San Nicola Section, Gela, Sicily, Italy 37°08′49″N 14°12′13″E / 37.1469°N 14.2035°E / 37.1469; 14.2035
Lower GSSP ratified	2009 (as base of Quaternary and Pleistocene)[3]
Upper boundary definition	End of the Younger Dryas stadial
Upper boundary GSSP	NGRIP2 ice core, Greenland 75°06′00″N 42°19′12″W / 75.1000°N 42.3200°W / 75.1000; -42.3200
Upper GSSP ratified	2008 (as base of Holocene)[4]

The Pleistocene (/ˈplaɪstəˌsiːn, -stoʊ-/ PLY-stə-seen, -⁠stoh-;^[5][6] referred to colloquially as the Ice Age) is the geological epoch that lasted from c. 2.58 million to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in 2009 by the International Union of Geological Sciences, the cutoff of the Pleistocene and the preceding Pliocene was regarded as being 1.806 million years Before Present (BP). Publications from earlier years may use either definition of the period. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the Paleolithic age used in archaeology. The name is a combination of Ancient Greek πλεῖστος (pleîstos) 'most' and καινός (kainós; Latinized as cænus) 'new'.

At the end of the preceding Pliocene, the previously isolated North and South American continents were joined by the Isthmus of Panama, causing a faunal interchange between the two regions and changing ocean circulation patterns, with the onset of glaciation in the Northern Hemisphere occurring around 2.7 million years ago. During the Early Pleistocene (2.58–0.8 Ma), archaic humans of the genus Homo originated in Africa and spread throughout Afro-Eurasia. The end of the Early Pleistocene is marked by the Mid-Pleistocene Transition, with the cyclicity of glacial cycles changing from 41,000-year cycles to asymmetric 100,000-year cycles, making the climate variation more extreme. The Late Pleistocene witnessed the spread of modern humans outside of Africa as well as the extinction of all other human species. Humans also spread to the Australian continent and the Americas for the first time, co-incident with the extinction of most large-bodied animals in these regions.

The aridification and cooling trends of the preceding Neogene were continued in the Pleistocene. The climate was strongly variable depending on the glacial cycle, with the sea levels being up to 120 metres (390 ft) lower than present at peak glaciation, allowing the connection of Asia and North America via Beringia and the covering of most of northern North America by the Laurentide Ice Sheet.