View source for Quaternary

{{Short description|Third and current period of the Cenozoic Era, from 2.58 million years ago to the present}}
{{Other uses}}
{{EngvarB|date=March 2023}}
{{Use dmy dates|date=March 2023}}
{{Infobox geologic timespan
| name                         = Quaternary
| color                        = Quaternary
| top_bar                      =
| time_start                   = 2.58
| time_start_uncertainty       = 
| time_end                     = 0
| image_map                    = Mollweide.jpg
| caption_map                  = A map of Earth as it appears during the current Quaternary period, Holocene epoch
| image_outcrop                =
| caption_outcrop              =
| image_art                    =
| caption_art                  =
<!--Chronology-->  
| timeline                     = Quaternary
<!--Etymology-->
| name_formality               = Formal
| name_accept_date             =
| alternate_spellings          =
| synonym1                     =
| synonym1_coined              =
| synonym2                     =
| synonym2_coined              =
| synonym3                     =
| synonym3_coined              =
| nicknames                    =
| former_names                 =
| proposed_names               =
<!--Usage Information--> 
| celestial_body               = earth
| usage                        = Global ([[International Commission on Stratigraphy|ICS]])
| timescales_used              = ICS Time Scale
| formerly_used_by             =
| not_used_by                  =
<!--Definition-->
| chrono_unit                  = Period
| strat_unit                   = System
| proposed_by                  =
| timespan_formality           = Formal
| lower_boundary_def           = 
* Base of magnetic polarity chronozone C2r (Matuyama)
* Extinction of the [[Haptophyte]]s ''[[Discoaster|Discoaster pentaradiatus]]'' and ''[[Discoaster|Discoaster surculus]]''
| lower_gssp_location          = Monte San Nicola Section, [[Gela]], [[Sicily]], [[Italy]]
| lower_gssp_coords            = {{Coord|37.1469|N|14.2035|E|display=inline}}
| lower_gssp_accept_date       = 2009 (as base of Quaternary and Pleistocene)<ref>{{cite journal |last1=Gibbard |first1=Philip |last2=Head |first2=Martin |title=The newly-ratified definition of the Quaternary System/Period and redefinition of the Pleistocene Series/Epoch, and comparison of proposals advanced prior to formal ratification |journal=Episodes |date=September 2010 |volume=33 |issue=3 |pages=152–158 |doi=10.18814/epiiugs/2010/v33i3/002 |doi-access=free |url=https://stratigraphy.org/gssps/files/quaternary-pleistocene.pdf |access-date=8 December 2020}}</ref>
| upper_boundary_def           = Present day
| upper_gssp_location          = N/A
| upper_gssp_accept_date       = N/A
<!--Atmospheric and Climatic Data-->
| o2                           = 20.8 
| co2                          = 250 
| temp                         = 14 
| sea_level                    =
}}

The '''Quaternary''' ({{IPAc-en|k|w|ə|ˈ|t|ɜr|n|ər|i}} {{respell|kwə|TUR|nər|ee}}, {{IPAc-en|USalso|ˈ|k|w|ɒ|t|ər|n|ɛr|i}} {{respell|KWOT|ər|nerr|ee}}) is the current and most recent of the three [[period (geology)|periods]] of the [[Cenozoic]] [[era (geology)|Era]] in the [[geologic time scale]] of the [[International Commission on Stratigraphy]] (ICS), as well as the current and most recent of the twelve periods of the [[Phanerozoic]] eon.<ref name="ICS2013">{{cite web |last1=Cohen |first1=K. M. |last2=Finney |first2=S. C. |last3=Gibbard |first3=P. L. |last4=Fan |first4=J.-X. |title=International Chronostratigraphic Chart 2013 |url=http://www.stratigraphy.org/icschart/chronostratchart2013-01.pdf |website=stratigraphy.org |publisher=ICS |access-date=15 June 2014 |ref=ICS2013}}</ref> It follows the [[Neogene]] Period and spans from 2.6&nbsp;million years ago to the present.<ref name="ICS StratChart 2022-02">{{cite web |title=Stratigraphic Chart 2022 |url=https://stratigraphy.org/ICSchart/ChronostratChart2022-02.pdf |publisher=International Stratigraphic Commission | date=February 2022  |access-date=4 June 2022}}</ref> The Quaternary Period is divided into two epochs: the [[Pleistocene]] (2.6&nbsp;million years ago to 12 thousand years ago) and the [[Holocene]] (12 thousand years ago to today); a proposed third epoch, the [[Anthropocene]], was rejected in 2024 by [[IUGS]], the governing body of the ICS.

The Quaternary is typically defined by the [[Quaternary glaciation]], the cyclic growth and decay of continental [[ice sheet]]s related to the [[Milankovitch cycles]] and the associated climate and environmental changes that they caused.<ref name="Denton2010">{{cite journal |last1=Denton |first1=G. H. |last2=Anderson |first2=R. F. |last3=Toggweiler |first3=J. R. |last4=Edwards |first4=R. L. |last5=Schaefer |first5=J. M. |last6=Putnam |first6=A. E. |title=The Last Glacial Termination |journal=Science |year=2010 |volume=328 |issue=5986 |pages=1652–1656 |doi=10.1126/science.1184119 |pmid=20576882 |bibcode=2010Sci...328.1652D |ref=Denton2010|citeseerx=10.1.1.1018.5454 |s2cid=27485445 }}</ref><ref>{{cite book |last1=Lowe |first1=J. J. |last2=Walker |first2=M. J. C. |title=Reconstructing Quaternary Environments |date=1997 |publisher=Routledge |isbn=978-0582101661}}</ref>

==Research history==
{{See also|Quaternary science}}
In 1759 [[Giovanni Arduino (geologist)|Giovanni Arduino]] proposed that the geological strata of northern [[Italy (geographical region)|Italy]] could be divided into four successive formations or "orders" ({{langx|it|quattro ordini}}).<ref>See:
* {{cite journal |last1=Arduino |first1=Giovanni |title=Lettera Segonda di Giovanni Arduino … sopra varie sue osservazioni fatte in diverse parti del territorio di Vicenza, ed altrove, apparenenti alla Teoria terrestre, ed alla Mineralogia |journal=Nuova Raccolta d'Opuscoli Scientifici e Filologici [New collection of scientific and philogical pamphlets] |year=1760 |volume=6 |pages=133 (cxxxiii)–180(clxxx) |trans-title=Second letter of Giovani Arduino … on his various observations made in different parts of the territory of Vincenza, and elsewhere, concerning the theory of the earth and mineralogy |language=it}}  Available at: [https://bibdig.museogalileo.it/Teca/Viewer;jsessionid=3160EE486323866602B9590459D7111B?an=323812_6 Museo Galileo (Florence (Firenze), Italy)]  From p. 158 (clviii):  ''"Per quanto ho potuto sinora osservavare, la serie di questi strati, che compongono la corteccia visibile della terra, mi pare distinta in quattro ordini generali, e successivi, senza considerarvi il mare."'' (As far as I have been able to observe, the series of these layers that compose the visible crust of the earth seems to me distinct in four general orders, and successive, not considering the sea.)
* English translation:  {{cite journal |last1=Ell |first1=Theodore |title=Two letters of Signor Giovanni Arduino, concerning his natural observations: first full English translation. Part 2. |journal=Earth Sciences History |year=2012 |volume=31 |issue=2 |pages=168–192|doi=10.17704/eshi.31.2.c2q4076006wn7751 |bibcode=2012ESHis..31..168E }}</ref> The term "quaternary" was introduced by [[Jules Desnoyers]] in 1829 for sediments of [[France]]'s [[Seine]] Basin that clearly seemed to be younger than [[Tertiary (period)|Tertiary]] [[Period (geology)|Period]] [[rock (geology)|rocks]].<ref>{{cite journal |last1=Desnoyers |first1=J. |title=Observations sur un ensemble de dépôts marins plus récents que les terrains tertiaires du bassin de la Seine, et constituant une formation géologique distincte; précédées d'un aperçu de la nonsimultanéité des bassins tertiares |journal=Annales des Sciences Naturelles |year=1829 |volume=16 |pages=171–214, 402–491 |url=https://www.biodiversitylibrary.org/item/29350#page/177/mode/1up |trans-title=Observations on a set of marine deposits [that are] more recent than the tertiary terrains of the Seine basin and [that] constitute a distinct geological formation; preceded by an outline of the non-simultaneity of tertiary basins |language=fr}} [https://www.biodiversitylibrary.org/item/29350#page/199/mode/1up From p. 193:]  ''"Ce que je désirerais … dont il faut également les distinguer."'' (What I would desire to prove above all is that the series of tertiary deposits continued – and even began in the more recent basins – for a long time, perhaps after that of the Seine had been completely filled, and that these later formations – ''Quaternary'' (1), so to say – should not retain the name of alluvial deposits any more than the true and ancient tertiary deposits, from which they must also be distinguished.)  However, on the very same page, Desnoyers abandoned the use of the term "quaternary" because the distinction between quaternary and tertiary deposits wasn't clear.  From p. 193:  ''"La crainte de voir mal comprise … que ceux du bassin de la Seine."'' (The fear of seeing my opinion in this regard be misunderstood or exaggerated, has made me abandon the word "quaternary", which at first I had wanted to apply to all deposits more recent than those of the Seine basin.)</ref><ref>{{Cite web|url=http://shodhganga.inflibnet.ac.in/bitstream/10603/77123/8/08_chapter%201.pdf|title=Late Quaternary Fluvial and Coastal Sequences Chapter 1: Introduction|access-date=26 March 2017}}</ref><ref>{{Citation|last=Wiz Science™|title=Quaternary - Video Learning |date=28 September 2015|url=https://www.youtube.com/watch?v=Io7vhansU1o| archive-url=https://web.archive.org/web/20170407105401/https://www.youtube.com/watch?v=Io7vhansU1o| archive-date=7 April 2017 | url-status=dead|access-date=26 March 2017}}</ref>

The Quaternary Period follows the [[Neogene]] Period and extends to the present. The Quaternary covers the time span of [[glacier|glaciations]] classified as the [[Pleistocene]], and includes the present interglacial time-period, the [[Holocene]].

This places the start of the Quaternary at the onset of [[Northern Hemisphere]] glaciation approximately 2.6&nbsp;million years ago ([[wikt:mya|mya]]). Prior to 2009, the Pleistocene was defined to be from 1.805&nbsp;million years ago to the present, so the current definition of the Pleistocene includes a portion of what was, prior to 2009, defined as the [[Pliocene]].

Quaternary stratigraphers usually worked with regional subdivisions. From the 1970s, the [[International Commission on Stratigraphy]] (ICS) tried to make a single geologic time scale based on [[GSSP]]'s, which could be used internationally. The Quaternary subdivisions were defined based on [[biostratigraphy]] instead of [[paleoclimate]].

This led to the problem that the proposed base of the Pleistocene was at 1.805&nbsp;million years ago, long after the start of the major glaciations of the northern hemisphere. The ICS then proposed to abolish use of the name Quaternary altogether, which appeared unacceptable to the [[International Union for Quaternary Research]] (INQUA).

In 2009, it was decided to make the Quaternary the youngest period of the [[Cenozoic]] Era with its base at 2.588&nbsp;mya and including the [[Gelasian]] Stage, which was formerly considered part of the Neogene Period and Pliocene Epoch.<ref name="ICS2009">{{cite web| url = http://www.quaternary.stratigraphy.org.uk/correlation/GSAchron09.jpg| title = See the 2009 version of the ICS geologic time scale}}</ref> This was later revised to 2.58&nbsp;mya.<ref name="ICS StratChart 2022-02" /><ref name="ICS StratChart Revisions">{{cite web | url=https://stratigraphy.org/ICSchart/ChangeLog2012-2022.txt | title=International Chronostratigraphic Chart ChangeLog for 2012-2022 | work=International Chronostratigraphic Chart | publisher=[[International Commission on Stratigraphy]] | date=February 2022 | accessdate=4 June 2022}}</ref>  

The [[Anthropocene]] was proposed as a third epoch as a mark of the anthropogenic impact on the global environment starting with the [[Industrial Revolution]], or about 200 years ago.<ref name="Zalasiewicz2011">{{cite journal |last1=Zalasiewicz |first1=J. |last2=Williams |first2=M. |last3=Haywood |first3=A. |last4=Ellis |first4=M. |title=The Anthropocene: a new epoch of geological time? |journal=Philosophical Transactions of the Royal Society A |year=2011 |volume=369 |issue=1938 |pages=835–841 |doi=10.1098/rsta.2010.0339 |ref=Zalasiewicz2011 |pmid=21282149|bibcode=2011RSPTA.369..835Z |s2cid=2624037 |url=http://nora.nerc.ac.uk/id/eprint/14867/1/Anthropocene_overview.pdf |doi-access=free }}</ref> The Anthropocene was rejected as a geological epoch in 2024 by the [[International Union of Geological Sciences]] (IUGS), the governing body of the ICS.<ref name="IUGS2024">The Anthropocene: IUGS-ICS Statement. March 20, 2024/https://www.iugs.org/_files/ugd/f1fc07_ebe2e2b94c35491c8efe570cd2c5a1bf.pdf</ref>

==Geology==
{{further|Quaternary geology}}	
The 2.58&nbsp;million years of the Quaternary represents the time during which recognisable humans existed.<ref name="autogenerated1">{{cite news |last=Ghosh |first=Pallab |author-link=Pallab Ghosh |date=4 March 2015 |title='First human' discovered in Ethiopia |url=https://www.bbc.com/news/science-environment-31718336 |work=BBC News |location=London |access-date=19 April 2015}}</ref> Over this geologically short time period there has been relatively little change in the distribution of the continents due to [[plate tectonics]].

The Quaternary geological record is preserved in greater detail than that for earlier periods.

The major geographical changes during this time period included the emergence of the straits of [[Bosphorus]] and [[Skagerrak]] during glacial epochs, which respectively turned the [[Black Sea]] and [[Baltic Sea]] into fresh water lakes, followed by their flooding (and return to salt water) by rising sea level;<ref>{{cite journal |last1=Ryan |first1=William B.F. |last2=Pitman |first2=Walter C. |last3=Major |first3=Candace O. |last4=Shimkus |first4=Kazimieras |last5=Moskalenko |first5=Vladamir |last6=Jones |first6=Glenn A. |last7=Dimitrov |first7=Petko |last8=Gorür |first8=Naci |last9=Sakinç |first9=Mehmet |last10=Yüce |first10=Hüseyin |title=An abrupt drowning of the Black Sea shelf |journal=Marine Geology |date=April 1997 |volume=138 |issue=1–2 |pages=119–126 |doi=10.1016/s0025-3227(97)00007-8|bibcode=1997MGeol.138..119R |s2cid=129316719 |doi-access=free }}</ref> the periodic filling of the [[English Channel]], forming a land bridge between Britain and the European mainland; the periodic closing of the [[Bering Strait]], forming [[Beringia|the land bridge between Asia and North America]]; and the periodic flash flooding of [[Scablands]] of the American Northwest by glacial water.<ref name="Balbas2017a">Balbas, A.M., Barth, A.M., Clark, P.U., Clark, J., Caffee, M., O'Connor, J., Baker, V.R., Konrad, K. and Bjornstad, B., 2017. [https://pubs.geoscienceworld.org/gsa/geology/article-abstract/45/7/583/207857/10be-dating-of-late-pleistocene-megafloods-and ''10Be dating of late Pleistocene megafloods and Cordilleran Ice Sheet retreat in the northwestern United States.''] ''Geology'', 45(7), pp. 583-586.</ref>

The current extent of [[Hudson Bay]], the [[Great Lakes]] and other major lakes of North America are a consequence of the [[Canadian Shield]]'s readjustment since the last ice age; different shorelines have existed over the course of Quaternary time.<ref>{{cite journal |last1=Dyke |first1=Arthur S. |title=An outline of North American deglaciation with emphasis on central and northern Canada |journal=Developments in Quaternary Sciences |year=2004 |volume=2 |pages=373–424 |doi=10.1016/S1571-0866(04)80209-4|isbn=9780444515926 }}</ref>

==Climate==
{{Further|Quaternary glaciation|Last Glacial Period}}

The [[climate]] was one of periodic glaciations with continental glaciers moving as far from the poles as 40 degrees [[latitude]]. Glaciation took place repeatedly during the Quaternary [[Ice age]]&nbsp;– a term coined by Schimper in 1839 that began with the start of the Quaternary about 2.58 Mya and continues to the present day.[[File:IceAgeEarth.jpg|thumb|Artist's impression of Earth during the [[Last Glacial Maximum]]]]
In 1821, a [[Switzerland|Swiss]] engineer, [[Ignaz Venetz]], presented an article in which he suggested the presence of traces of the passage of a glacier at a considerable distance from the Alps. This idea was initially disputed by another Swiss scientist, [[Louis Agassiz]], but when he undertook to disprove it, he ended up affirming his colleague's hypothesis. A year later, Agassiz raised the hypothesis of a great glacial period that would have had long-reaching general effects. This idea gained him international fame and led to the establishment of the Glacial Theory.

In time, thanks to the refinement of geology, it has been demonstrated that there were several periods of glacial advance and retreat and that past temperatures on Earth were very different from today.
In particular, the [[Milankovitch cycles]] of [[Milutin Milankovitch]] are based on the premise that variations in incoming [[solar radiation]] are a fundamental factor controlling Earth's climate.

During this time, substantial glaciers advanced and retreated over much of North America and Europe, parts of South America and Asia, and all of Antarctica.

== Flora and fauna ==
{{Expand section|date=March 2023}}
{{Further|Late Pleistocene extinctions}}
There was a major [[extinction]] of large mammals globally during the [[Late Pleistocene]] Epoch.<ref>{{Cite journal |last1=Barnosky |first1=Anthony D. |last2=Koch |first2=Paul L. |last3=Feranec |first3=Robert S. |last4=Wing |first4=Scott L. |last5=Shabel |first5=Alan B. |date=October 2004 |title=Assessing the Causes of Late Pleistocene Extinctions on the Continents |url=https://www.science.org/doi/10.1126/science.1101476 |journal=Science |language=en |volume=306 |issue=5693 |pages=70–75 |doi=10.1126/science.1101476 |pmid=15459379 |bibcode=2004Sci...306...70B |issn=0036-8075|url-access=subscription }}</ref> Many forms such as [[sabre-toothed cat]]s, [[mammoth]]s, [[mastodon]]s, [[glyptodon]]ts, etc., became extinct worldwide. Others, including [[horse]]s, [[Camelops|camels]] and [[American cheetah]]s became extinct in [[North America]].<ref>{{Cite web |last=Haynes |title=Stanford Camelops |url=http://www.unr.edu/cla/anthro/people/faculty/haynes/download%20Haynes+StanfordCamelops.pdf |url-status=dead |archive-url=https://web.archive.org/web/20140309104319/http://www.unr.edu/cla/anthro/people/faculty/haynes/download%20Haynes+StanfordCamelops.pdf |archive-date=9 March 2014}}</ref><ref>{{Cite web |title=Extinct American Cheetah Fact Sheet |url=http://library.sandiegozoo.org/factsheets/_extinct/cheetah1_american/cheetah1_american.html |url-status=dead |archive-url=https://web.archive.org/web/20160304023142/http://library.sandiegozoo.org/factsheets/_extinct/cheetah1_american/cheetah1_american.html |archive-date=4 March 2016 |access-date=10 December 2015 |website=library.sandiegozoo.org}}</ref>

The [[Great Lakes]] formed and giant mammals thrived in parts of North America and Eurasia not covered in ice. These mammals became extinct when the glacial period ended about 11,700 years ago. Modern [[humans]] evolved about 315,000 years ago. During the Quaternary Period, mammals, flowering plants, and insects dominated the land.{{Citation needed|date=September 2009}}

==See also==
* [[List of Quaternary volcanic eruptions]]

==References==
{{reflist}}

==External links==
{{Wikisource portal|Cenozoic#Quaternary}}
*[http://quaternary.stratigraphy.org/ Subcommission on Quaternary Stratigraphy]
*[http://quaternary.stratigraphy.org/charts/ Stratigraphical charts for the Quaternary]
*[http://quaternary.stratigraphy.org/charts/version-history/ Version history of the global Quaternary chronostratigraphical charts (from 2004b)]
* Silva, P.G. C. Zazo, T. Bardají, J. Baena, J. Lario, A. Rosas, J. Van der Made. 2009, "[https://web.archive.org/web/20120626140850/http://tierra.rediris.es/aequa/doc/tabla_aequav2_2009.pdf Tabla Cronoestratigrafíca del Cuaternario en la Península Ibérica - V.2]". [Versión PDF, 3.6 [[Megabyte|Mb]]]. Asociación Española para el Estudio del Cuaternario (AEQUA), Departamento de Geología, [[Universidad de Salamanca]], Spain. (Correlation chart of European Quaternary and cultural stages and fossils)
* [http://ice.tsu.ru/index.php?view=category&catid=27&option=com_joomgallery&Itemid=40 Welcome to the XVIII INQUA-Congress, Bern, 2011] {{Webarchive|url=https://web.archive.org/web/20120321083821/http://ice.tsu.ru/index.php?view=category&catid=27&option=com_joomgallery&Itemid=40 |date=21 March 2012 }}
* [https://ghkclass.com/ghkC.html?quaternary Quaternary (chronostratigraphy scale)] {{Webarchive|url=https://web.archive.org/web/20200427131947/https://ghkclass.com/ghkC.html?quaternary |date=27 April 2020 }}
* {{commons category-inline|Quaternary}}

{{Quaternary Footer}}
{{Geological history|p|c}}
{{Physical geography topics}}



[[Category:Quaternary| ]]
[[Category:Geological periods]]
[[Category:Physical geography]]
[[Category:Physical oceanography]]