Plio-Pleistocene
ThePlio-Pleistoceneis an informally described geological pseudo-period, which begins about 5 million years ago (Mya) and, drawing forward, combines the time ranges of the formally definedPlioceneandPleistoceneepochs—marking from about 5 Mya to about 12 kya. Nominally, theHoloceneepoch—the last 12 thousand years—would be excluded, but most Earth scientists would probably treat the current times as incorporated into the term "Plio-Pleistocene";[1]see below.
In the contexts ofarchaeology,paleontology,andpaleoanthropology,the Plio-Pleistocene is a very useful period to which scientists may assign the long and continuous run inEast Africaof datable sedimentary layers and their contents (e.g. theBouri Formation). These contents collectively present a focused view of the continuous evolution of the region's largevertebrates,especially the evolution of some African apes (hominids) to the earliesthominins;and then the development of the early humans and their toolmaking cultures. This shorter pseudo-period—fromafter5 Mya to about 1.5 Mya—straddles the boundary between the Pliocene and the Pleistocene. Thereafter the Plio-Pleistocene formations in East Africa contain, and disclose, the genusHomodeveloping into archaicHomo sapiens,then toanatomically modern humans.
The term is also useful inclimatologyandEarth sciencesbecause the greater Plio-Pleistocene period covers the gradual but prolonged long-term cooling of the Earth's atmosphere from the generally warmer temperatures of the lateOligocene/ earlyNeogenetimes to and continuing through theLate Pleistocene—and indeed continuing through current times, if the present interglacial warming is considered as merely superimposed on the longer trend of cooling.[2]Beginning about 3 Mya, the late Pliocene saw the start of glaciation in the Northern Hemisphere,[3]and many authors may informally use the term "Plio-Pleistocene" as a synonym for the period during which the Northern Hemisphere has been glaciated.
See also
[edit]- Australopithecine,straddle the Plio-Pleistocene
References
[edit]- ^Anderson, R.S.;Molnar, P.;Kessler, M.A. (2006). "Features of glacial valley profiles simply explained".Journal of Geophysical Research.111(F1).Bibcode:2006JGRF..111.1004A.doi:10.1029/2005JF000344.ISSN0148-0227.WikidataQ59665231.
- ^Lisiecki, L.E.;Raymo, M.E.(18 January 2005). "A Pliocene-Pleistocene stack of 57 globally distributed benthic δ18O records".Paleoceanography.20(1).Bibcode:2005PalOc..20.1003L.doi:10.1029/2004PA001071.ISSN0883-8305.WikidataQ54015301.(erratum)
- ^G. Bartoli;M. Sarnthein;M. Weinelt; H. Erlenkeuser; D. Garbe-Schönberg; D.W. Lea (August 2005). "Final closure of Panama and the onset of northern hemisphere glaciation".Earth and Planetary Science Letters.237(1–2): 33–44.Bibcode:2005E&PSL.237...33B.doi:10.1016/J.EPSL.2005.06.020.ISSN0012-821X.WikidataQ56058938.