Quaternary Explained

Quaternary
Color:Quaternary
Time Start:2.58
Time End:0
Caption Map:A map of the world as it appeared during the Pleistocene epoch, c. 1 Ma
Timeline:Quaternary
Name Formality:Formal
Celestial Body:earth
Usage:Global (ICS)
Timescales Used:ICS Time Scale
Chrono Unit:Period
Strat Unit:System
Timespan Formality:Formal
Lower Boundary Def:
Lower Gssp Location:Monte San Nicola Section, Gela, Sicily, Italy
Lower Gssp Accept Date:2009 (as base of Quaternary and Pleistocene)[1]
Upper Boundary Def:Present day
Upper Gssp Location:N/A
Upper Gssp Accept Date:N/A
O2:20.8
Co2:250
Temp:14

The Quaternary 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).[2] It follows the Neogene Period and spans from 2.58 million years ago to the present.[3] 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 proposed third epoch, the Anthropocene, was rejected in 2024 by IUGS, the governing body of the ICS.

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.[4] [5]

Research history

See also: Quaternary science. In 1759 Giovanni Arduino proposed that the geological strata of northern Italy could be divided into four successive formations or "orders" (Italian: quattro ordini).[6] 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 rocks.[7] [8]

The Quaternary Period follows the Neogene Period and extends to the present. The Quaternary covers the time span of 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 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 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 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 mya and including the Gelasian Stage, which was formerly considered part of the Neogene Period and Pliocene Epoch.[9] This was later revised to 2.58 mya.[10]

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.[11] The Anthropocene was rejected as a geological epoch in 2024 by the International Union of Geological Sciences (IUGS), the governing body of the ICS.[12]

Geology

The 2.58 million years of the Quaternary represents the time during which recognisable humans existed.[13] 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 Strait 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;[14] 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 the land bridge between Asia and North America; and the periodic flash flooding of Scablands of the American Northwest by glacial water.[15]

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.[16]

Climate

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 – 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.In 1821, a 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

There was a major extinction of large mammals globally during the Late Pleistocene Epoch.[17] Many forms such as sabre-toothed cats, mammoths, mastodons, glyptodonts, etc., became extinct worldwide. Others, including horses, camels and American cheetahs became extinct in North America.[18] [19]

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.

See also

External links

Notes and References

  1. Gibbard . Philip . Head . Martin . 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 . Episodes . September 2010 . 33 . 3 . 152–158 . 10.18814/epiiugs/2010/v33i3/002 . 8 December 2020.
  2. Web site: Cohen . K.M. . Finney . S.C. . Gibbard . P.L. . Fan . J.-X. . International Chronostratigraphic Chart 2013 . stratigraphy.org . ICS . 15 June 2014 . ICS2013.
  3. Web site: Stratigraphic Chart 2022 . International Stratigraphic Commission . February 2022 . 4 June 2022.
  4. Denton . G.H. . Anderson . R.F. . Toggweiler . J.R. . Edwards . R.L. . Schaefer . J.M. . Putnam . A.E. . The Last Glacial Termination . Science . 2010 . 328 . 5986 . 1652–1656 . 10.1126/science.1184119 . 20576882 . 2010Sci...328.1652D . Denton2010. 10.1.1.1018.5454 . 27485445 .
  5. Book: Lowe . J.J. . Walker . M.J.C. . Reconstructing Quaternary Environments . 1997 . Routledge . 978-0582101661.
  6. See:
    • Arduino . Giovanni . 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 . Nuova Raccolta d'Opuscoli Scientifici e Filologici [New collection of scientific and philogical pamphlets] . 1760 . 6 . 133 (cxxxiii)–180(clxxx) . 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 . it. 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 . Two letters of Signor Giovanni Arduino, concerning his natural observations: first full English translation. Part 2. . Earth Sciences History . 2012 . 31 . 2 . 168–192. 10.17704/eshi.31.2.c2q4076006wn7751 . 2012ESHis..31..168E .
  7. Desnoyers . J. . 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 . Annales des Sciences Naturelles . 1829 . 16 . 171–214, 402–491 . 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 . fr. 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.)
  8. Web site: Late Quaternary Fluvial and Coastal Sequences Chapter 1: Introduction. 26 March 2017.
  9. Web site: See the 2009 version of the ICS geologic time scale.
  10. Web site: International Chronostratigraphic Chart ChangeLog for 2012-2022 . International Chronostratigraphic Chart . . February 2022 . 4 June 2022.
  11. Zalasiewicz . J. . Williams . M. . Haywood . A. . Ellis . M. . The Anthropocene: a new epoch of geological time? . Philosophical Transactions of the Royal Society A . 2011 . 369 . 1938 . 835–841 . 10.1098/rsta.2010.0339 . Zalasiewicz2011 . 21282149. 2011RSPTA.369..835Z . 2624037 . free .
  12. The Anthropocene: IUGS-ICS Statement. March 20, 2024/https://www.iugs.org/_files/ugd/f1fc07_ebe2e2b94c35491c8efe570cd2c5a1bf.pdf
  13. News: Ghosh . Pallab . Pallab Ghosh . 4 March 2015 . 'First human' discovered in Ethiopia . BBC News . London . 19 April 2015.
  14. 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 . An abrupt drowning of the Black Sea shelf . Marine Geology . April 1997 . 138 . 1–2 . 119–126 . 10.1016/s0025-3227(97)00007-8. 1997MGeol.138..119R . 129316719 . free .
  15. 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.
  16. Dyke . Arthur S. . An outline of North American deglaciation with emphasis on central and northern Canada . Developments in Quaternary Sciences . 2004 . 2 . 373–424 . 10.1016/S1571-0866(04)80209-4. 9780444515926 .
  17. 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 . en . 306 . 5693 . 70–75 . 10.1126/science.1101476 . 15459379 . 2004Sci...306...70B . 0036-8075.
  18. Web site: Haynes . Stanford Camelops . dead . https://web.archive.org/web/20140309104319/http://www.unr.edu/cla/anthro/people/faculty/haynes/download%20Haynes+StanfordCamelops.pdf . 9 March 2014.
  19. Web site: Extinct American Cheetah Fact Sheet . dead . https://web.archive.org/web/20160304023142/http://library.sandiegozoo.org/factsheets/_extinct/cheetah1_american/cheetah1_american.html . 4 March 2016 . 10 December 2015 . library.sandiegozoo.org.

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