Jump to content

Quaternary

From Wikipedia, the free encyclopedia
For other uses, seeQuaternary (disambiguation).

Quaternary
2.58 – 0Ma
↓
A map of the world as it appeared during the Pleistocene epoch, c. 1 Ma[citation needed]
Chronology
Etymology
Name formalityFormal
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitPeriod
Stratigraphic unitSystem
Time span formalityFormal
Lower boundary definition
Lower boundary GSSPMonte San Nicola Section,Gela,Sicily,Italy
37°08′49″N14°12′13″E/ 37.1469°N 14.2035°E/37.1469; 14.2035
Lower GSSP ratified2009 (as base of Quaternary and Pleistocene)[3]
Upper boundary definitionPresent day
Upper boundary GSSPN/A
Upper GSSP ratifiedN/A
Atmospheric and climatic data
Mean atmosphericO2contentc. 20.8 vol %
(100 % of modern)
Mean atmosphericCO2contentc. 250ppm
(0.9 times pre-industrial)
Mean surface temperaturec. 14 °C
(0.5 °C above pre-industrial)

TheQuaternary(/kwəˈtɜːrnəri,ˈkwɒtərnɛri/kwə-TUR-nə-ree,KWOT-ər-nerr-ee) is the current and most recent of the threeperiodsof theCenozoicErain thegeologic time scaleof theInternational Commission on Stratigraphy(ICS).[4]It follows theNeogenePeriod and spans from 2.58 million years ago to the present.[5]As of 2023, the Quaternary Period is divided into two epochs: thePleistocene(2.58 million years ago to 11.7 thousand years ago) and theHolocene(11.7 thousand years ago to today); a third epoch, theAnthropocene,has recently been proposed, but it is not officially recognised by the ICS.

The Quaternary Period is typically defined by the cyclic growth and decay of continentalice sheetsrelated to theMilankovitch cyclesand the associated climate and environmental changes that they caused.[6][7]

Research history[edit]

See also:Quaternary science

In 1759Giovanni Arduinoproposed that the geological strata of northernItalycould be divided into four successive formations or "orders" (Italian:quattro ordini).[8]The term "quaternary" was introduced byJules Desnoyersin 1829 for sediments ofFrance'sSeineBasin that clearly seemed to be younger thanTertiaryPeriodrocks.[9][10][11]

The Quaternary Period follows theNeogenePeriod and extends to the present. The Quaternary covers the time span ofglaciationsclassified as thePleistocene,and includes the present interglacial time-period, theHolocene.

This places the start of the Quaternary at the onset ofNorthern Hemisphereglaciation approximately 2.6 million years ago (mya). Prior to 2009, the Pleistocene was defined to be from 1.805 million years ago to the present, so the current definition of the Pleistocene includes a portion of what was, prior to 2009, defined as thePliocene.

Quaternary stratigraphers usually worked with regional subdivisions. From the 1970s, theInternational Commission on Stratigraphy(ICS) tried to make a single geologic time scale based onGSSP's, which could be used internationally. The Quaternary subdivisions were defined based onbiostratigraphyinstead ofpaleoclimate.

This led to the problem that the proposed base of the Pleistocene was at 1.805 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 theInternational Union for Quaternary Research(INQUA).

In 2009, it was decided to make the Quaternary the youngest period of theCenozoicEra with its base at 2.588 mya and including theGelasianStage, which was formerly considered part of the Neogene Period and Pliocene Epoch.[12]This was later revised to 2.58 mya.[5][13]

TheAnthropocenehas been proposed as a third epoch as a mark of the anthropogenic impact on the global environment starting with theIndustrial Revolution,or about 200 years ago.[14]The Anthropocene is not officially designated by the ICS, but a working group has been working on a proposal for the creation of an epoch or sub-period.[15]

Geology[edit]

Further information:Quaternary geology

The 2.58 million years of the Quaternary represents the time during which recognisable humans existed.[16]Over this geologically short time period there has been relatively little change in the distribution of the continents due toplate 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 Strait ofBosphorusandSkagerrakduring glacial epochs, which respectively turned theBlack SeaandBaltic Seainto fresh water lakes, followed by their flooding (and return to salt water) by rising sea level;[17]the periodic filling of theEnglish Channel,forming a land bridge between Britain and the European mainland; the periodic closing of theBering Strait,formingthe land bridge between Asia and North America;and the periodic flash flooding ofScablandsof the American Northwest by glacial water.[18]

The current extent ofHudson Bay,theGreat Lakesand other major lakes of North America are a consequence of theCanadian Shield's readjustment since the last ice age; different shorelines have existed over the course of Quaternary time.[19]

Climate[edit]

Further information:Quaternary glaciationandLast Glacial Period

Theclimatewas one of periodic glaciations with continental glaciers moving as far from the poles as 40 degreeslatitude.Glaciation took place repeatedly during the QuaternaryIce age– 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.

Artist's impression of Earth during theLast Glacial Maximum

In 1821, aSwissengineer,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, theMilankovitch cyclesofMilutin Milankovitchare based on the premise that variations in incomingsolar radiationare 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[edit]

Further information:Late Pleistocene extinctions

There was a majorextinctionof large mammals globally during theLate PleistoceneEpoch.[20]Many forms such assabre-toothed cats,mammoths,mastodons,glyptodonts,etc., became extinct worldwide. Others, includinghorses,camelsandAmerican cheetahsbecame extinct inNorth America.[21][22]

TheGreat Lakesformed 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. Modernhumansevolved about 315,000 years ago. During the Quaternary Period, mammals, flowering plants, and insects dominated the land.[citation needed]

See also[edit]

References[edit]

  1. ^Cohen, K. M.; Finney, S. C.; Gibbard, P. L.; Fan, J.-X. (January 2020)."International Chronostratigraphic Chart"(PDF).International Commission on Stratigraphy.Retrieved23 February2020.
  2. ^Mike Walker; et al. (December 2018)."Formal ratification of the subdivision of the Holocene Series/Epoch (Quaternary System/Period)"(PDF).Episodes.41(4). Subcommission on Quaternary Stratigraphy (SQS): 213–223.doi:10.18814/epiiugs/2018/018016.Retrieved11 November2019.
  3. ^Gibbard, Philip; Head, Martin (September 2010)."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"(PDF).Episodes.33(3): 152–158.doi:10.18814/epiiugs/2010/v33i3/002.Retrieved8 December2020.
  4. ^Cohen, K.M.; Finney, S.C.; Gibbard, P.L.; Fan, J.-X."International Chronostratigraphic Chart 2013"(PDF).stratigraphy.org.ICS.Retrieved15 June2014.
  5. ^ab"Stratigraphic Chart 2022"(PDF).International Stratigraphic Commission. February 2022.Retrieved4 June2022.
  6. ^Denton, G.H.; Anderson, R.F.; Toggweiler, J.R.; Edwards, R.L.; Schaefer, J.M.; Putnam, A.E. (2010). "The Last Glacial Termination".Science.328(5986): 1652–1656.Bibcode:2010Sci...328.1652D.CiteSeerX10.1.1.1018.5454.doi:10.1126/science.1184119.PMID20576882.S2CID27485445.
  7. ^Lowe, J.J.; Walker, M.J.C. (1997).Reconstructing Quaternary Environments.Routledge.ISBN978-0582101661.
  8. ^See:
    • Arduino, Giovanni (1760). "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" [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].Nuova Raccolta d'Opuscoli Scientifici e Filologici [New collection of scientific and philogical pamphlets](in Italian).6:133 (cxxxiii)–180(clxxx).Available at: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:Ell, Theodore (2012). "Two letters of Signor Giovanni Arduino, concerning his natural observations: first full English translation. Part 2".Earth Sciences History.31(2): 168–192.Bibcode:2012ESHis..31..168E.doi:10.17704/eshi.31.2.c2q4076006wn7751.
  9. ^Desnoyers, J. (1829)."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"[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].Annales des Sciences Naturelles(in French).16:171–214, 402–491.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.)
  10. ^"Late Quaternary Fluvial and Coastal Sequences Chapter 1: Introduction"(PDF).Retrieved26 March2017.
  11. ^Wiz Science™ (28 September 2015),Quaternary - Video Learning,archived fromthe originalon 7 April 2017,retrieved26 March2017
  12. ^"See the 2009 version of the ICS geologic time scale".
  13. ^"International Chronostratigraphic Chart ChangeLog for 2012-2022".International Chronostratigraphic Chart.International Commission on Stratigraphy.February 2022.Retrieved4 June2022.
  14. ^Zalasiewicz, J.; Williams, M.; Haywood, A.; Ellis, M. (2011)."The Anthropocene: a new epoch of geological time?"(PDF).Philosophical Transactions of the Royal Society A.369(1938): 835–841.Bibcode:2011RSPTA.369..835Z.doi:10.1098/rsta.2010.0339.PMID21282149.S2CID2624037.
  15. ^"Working Group on the 'Anthropocene'".Subcomission on Quaternary Stratigraphy.Retrieved16 June2014.
  16. ^Ghosh, Pallab(4 March 2015)."'First human' discovered in Ethiopia ".BBC News.London.Retrieved19 April2015.
  17. ^Ryan, William B.F.; Pitman, Walter C.; Major, Candace O.; Shimkus, Kazimieras; Moskalenko, Vladamir; Jones, Glenn A.; Dimitrov, Petko; Gorür, Naci; Sakinç, Mehmet; Yüce, Hüseyin (April 1997)."An abrupt drowning of the Black Sea shelf".Marine Geology.138(1–2): 119–126.Bibcode:1997MGeol.138..119R.doi:10.1016/s0025-3227(97)00007-8.S2CID129316719.
  18. ^Balbas, A.M., Barth, A.M., Clark, P.U., Clark, J., Caffee, M., O'Connor, J., Baker, V.R., Konrad, K. and Bjornstad, B., 2017.10Be dating of late Pleistocene megafloods and Cordilleran Ice Sheet retreat in the northwestern United States.Geology,45(7), pp. 583-586.
  19. ^Dyke, Arthur S. (2004). "An outline of North American deglaciation with emphasis on central and northern Canada".Developments in Quaternary Sciences.2:373–424.doi:10.1016/S1571-0866(04)80209-4.ISBN9780444515926.
  20. ^Barnosky, Anthony D.; Koch, Paul L.; Feranec, Robert S.; Wing, Scott L.; Shabel, Alan B. (October 2004)."Assessing the Causes of Late Pleistocene Extinctions on the Continents".Science.306(5693): 70–75.Bibcode:2004Sci...306...70B.doi:10.1126/science.1101476.ISSN0036-8075.PMID15459379.
  21. ^Haynes."Stanford Camelops"(PDF).Archived fromthe original(PDF)on 9 March 2014.
  22. ^"Extinct American Cheetah Fact Sheet".library.sandiegozoo.org.Archived fromthe originalon 4 March 2016.Retrieved10 December2015.

External links[edit]

Wikisource has original works on the topic:Cenozoic#Quaternary
Retrieved from "https://en.wikipedia.org/w/index.php?title=Quaternary&oldid=1229040778"