Meghalayan

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Meghalayan
0.0042 – 0 Ma
Chronology
Etymology
Name formalityFormal
Name ratified14 June 2018[1][2]
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitAge
Stratigraphic unitStage
Time span formalityFormal
Lower boundary definition4.2 kiloyear event
Lower boundary GSSPMawmluh Cave, Meghalaya, India
25°15′44″N 91°42′54″E / 25.2622°N 91.7150°E / 25.2622; 91.7150
Lower GSSP ratified14 June 2018
Upper boundary definitionN/A
Upper boundary GSSPN/A
Upper GSSP ratifiedN/A

The Meghalayan age is the name given in 2018, by the International Commission on Stratigraphy, to the current age or latest geologic age – or uppermost stage of the Quaternary.[3] It is also the upper, or latest, of three subdivisions of the Holocene epoch or series.[4][5] This way of breaking down time is based only on geology; for example it's unrelated to the three age system of historical periods into which human development is sometimes divided.

The Meghalayan begins 4,200 years BP (c. 2251 BCE or 7750 HE),[6] leaving room for the possible introduction of the Anthropocene.[7][8] Helama & Oinonen (2019) dated the start of the Meghalayan to 2190-1990 BCE.[9] The age began with a 200-year drought that impacted human civilizations in the Eastern Mediterranean, Mesopotamia, the Indus Valley and the Yangtze River Valley.[6] "The fact that the beginning of this age coincides with a cultural shift caused by a global climate event makes it unique," according to Stanley Finney, Secretary General of the International Union of Geological Sciences.[8]

Origins[edit]

This age is named after Meghalaya, northern India, where the stalagmite was found that is used to mark out its years.

The International Commission on Stratigraphy officially ratified this age in June 2018, along with the earlier Greenlandian and Northgrippian ages/stages.[10] Its Global Boundary Stratotype Section and Point (GSSP) is a Krem Mawmluh Cave formation in Meghalaya, a state in Northeast India.[10] Mawmluh cave is one of the longest and deepest caves in India, and conditions there were suitable for preserving chemical signs of the transition in ages.[11] The global auxiliary stratotype is an ice core from Mount Logan in Canada.[12]

IUGS geological heritage site[edit]

In respect of the Mawmluh Cave site being the "GSSP of the youngest unit of the geologic time scale associated with dramatic climate changes with implications on human civilisation" the International Union of Geological Sciences (IUGS) included the GSSP of the Meghalayan Stage in the Mawmluh Cave in its assemblage of 100 "geological heritage sites" around the world in a listing published in October 2022. The organisation defines an IUGS Geological Heritage Site as "a key place with geological elements and/or processes of international scientific relevance, used as a reference, and/or with a substantial contribution to the development of geological sciences through history."[13]

See also[edit]

References[edit]

  1. ^ Walker, Mike; Head, Martin J.; Berkelhammer, Max; Björck, Svante; Cheng, Hai; Cwynar, Les; Fisher, David; Gkinis, Vasilios; Long, Anthony; Lowe, John; Newnham, Rewi; Rasmussen, Sune Olander; Weiss, Harvey (1 December 2018). "Formal ratification of the subdivision of the Holocene Series/ Epoch (Quaternary System/Period): two new Global Boundary Stratotype Sections and Points (GSSPs) and three new stages/subseries" (PDF). Episodes. Subcommission on Quaternary Stratigraphy (SQS). 41 (4): 213–223. doi:10.18814/epiiugs/2018/018016. Retrieved 28 August 2020. This proposal on behalf of the SQS has been approved by the International Commission on Stratigraphy (ICS) and formally ratified by the Executive Committee of the International Union of Geological Sciences (IUGS).
  2. ^ Head, Martin J. (17 May 2019). "Formal subdivision of the Quaternary System/Period: Present status and future directions". Quaternary International. 500: 32–51. Bibcode:2019QuInt.500...32H. doi:10.1016/j.quaint.2019.05.018.
  3. ^ Cohen, K. M.; Finney, S. C.; Gibbard, P. L.; Fan, J-X. (January 2020). "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. Retrieved 8 January 2021.
  4. ^ Radha-Udayakumar, Ganesh (19 July 2018). "Scientists call our era the Meghalayan Age. Here's what the world was like when it began". India Today. New Delhi: Living Media India Limited. Retrieved 3 January 2021.
  5. ^ "'Meghalayan Age': Latest phase in Earth's history named after Indian state, began 4,200 years ago". Scroll.in.
  6. ^ a b Jonathan Amos (18 July 2018). "Welcome to the Meghalayan Age – a new phase in history". BBC. Retrieved 19 July 2018.
  7. ^ International Commission on Stratigraphy. "Collapse of civilizations worldwide defines youngest unit of the Geologic Time Scale". News and Meetings. Retrieved 15 July 2018.
  8. ^ a b Michael Irving (19 July 2018). "Time for the Meghalayan: A new geological age has officially been declared". Archived from the original on 15 July 2018. Retrieved 19 July 2018.
  9. ^ Helama, Samuli; Oinonen, Markku (15 June 2019). "Exact dating of the Meghalayan lower boundary based on high-latitude tree-ring isotope chronology". Quaternary Science Reviews. 214: 178–184. Bibcode:2019QSRv..214..178H. doi:10.1016/j.quascirev.2019.04.013. hdl:10138/330959. ISSN 0277-3791. S2CID 150012152.
  10. ^ a b International Commission on Stratigraphy. "ICS chart containing the Quaternary and Cambrian GSSPs and new stages (v 2018/07) is now released!". Archived from the original on 19 February 2020. Retrieved 15 July 2018.
  11. ^ "'Meghalayan Age' makes the state a part of geologic history". Hindustan Times. 18 July 2018. Retrieved 26 July 2018.
  12. ^ "Formal subdivision of the Holocene Series/Epoch" (PDF).
  13. ^ "The First 100 IUGS Geological Heritage Sites" (PDF). IUGS International Commission on Geoheritage. IUGS. Retrieved 10 November 2022.

External links[edit]