Meghalayan

Subdivisions of the Quaternary System
System/
Period		 Series/
Epoch		 Stage/
Age		 Age (Ma)
Quaternary Holocene Meghalayan 0 0.0042
Northgrippian 0.0042 0.0082
Greenlandian 0.0082 0.0117
Pleistocene 'Tarantian' 0.0117 0.126
'Chibanian' 0.126 0.781
Calabrian 0.781 1.80
Gelasian 1.80 2.58
Neogene Pliocene Piacenzian older
Subdivision of the Quaternary period according to the ICS, as of 2018.[1]

For the Holocene, dates are relative to the year 2000 (e.g. Greenlandian began 11,700 years before 2000). For the begin of the Northgrippian a date of 8,236 years before 2000 has been set [2]. The Meghalayan has been set to begin 4,250 years before 2000, apparently from a calibrated radio-carbon date of 4,200 years BP i.e. before 1950.[3]

'Chibanian' and 'Tarantian' are informal, unofficial names proposed to replace the also informal, unofficial 'Middle Pleistocene' and 'Upper Pleistocene' subseries/subepochs respectively.

In Europe and North America, the Holocene is subdivided into Preboreal, Boreal, Atlantic, Subboreal, and Subatlantic stages of the Blytt–Sernander time scale. There are many regional subdivisions for the Upper or Late Pleistocene; usually these represent locally recognized cold (glacial) and warm (interglacial) periods. The last glacial period ends with the cold Younger Dryas substage.

In the geologic time scale, the Meghalayan is the latest age or uppermost stage of the Quaternary.[4] It is also the upper, or latest, of three subdivisions of the Holocene epoch or series.[5][6] Its Global Boundary Stratotype Section and Point (GSSP) is a Mawmluh cave formation in Meghalaya, northeast India.[7] Mawmluh cave is one of the longest and deepest caves in India, and conditions here were suitable for preserving chemical signs of the transition in ages.[8] The global auxiliary stratotype is an ice core from Mount Logan in Canada.[9]

The Meghalayan begins 4,200 years BP, i.e., before 1950 (c. 2250 BCE),[10] leaving open room for the possible creation of the Anthropocene from 1950 forward.[11][12] The age began with a 200-year drought which impacted human civilizations in Egypt, Greece, Syria, Canaan, Mesopotamia, the Indus Valley and the Yangtze River Valley.[10] "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.[12]

The age was officially ratified by the International Commission on Stratigraphy in July 2018 along with the Greenlandian and the Northgrippian.[7]

See also

References

  1. ↑ Cohen, K.M.; Finney, S.C.; Gibbard, P.L.; Fan, J.-X. "International Chronostratigraphic Chart". International Commission on Stratigraphy. Retrieved July 10, 2018.
  2. ↑ "IUGS ratifies Holocene". Retrieved 18 August 2018.
  3. ↑ "announcement ICS chart v2018/07". Retrieved 9 August 2018.
  4. ↑ Cohen, Kim Mikkel, David A. T. Harper, Philip Leonard Gibbard, and Junxuan Fan. "The ICS International Chronostratigraphic Chart". International Commission on Stratigraphy. Retrieved 15 July 2018.
  5. ↑ "Scientists call our era the Meghalayan Age. Here's what the world was like when it began".
  6. ↑ "'Meghalayan Age': Latest phase in Earth's history named after Indian state, began 4,200 years ago".
  7. 1 2 International Commission on Stratigraphy. "ICS chart containing the Quaternary and Cambrian GSSPs and new stages (v 2018/07) is now released!". Retrieved 15 July 2018.
  8. ↑ "'Meghalayan Age' makes the state a part of geologic history". https://www.hindustantimes.com/. 2018-07-18. Retrieved 2018-07-26. External link in |work= (help)
  9. ↑ Formal subdivision of the Holocene Series/Epoch
  10. 1 2 Jonathan Amos (July 18, 2018). "Welcome to the Meghalayan Age - a new phase in history". BBC. Retrieved July 19, 2018.
  11. ↑ International Commission on Stratigraphy. "Collapse of civilizations worldwide defines youngest unit of the Geologic Time Scale". News and Meetings. Retrieved 15 July 2018.
  12. 1 2 Michael Irving (July 19, 2018). "Time for the Meghalayan: A new geological age has officially been declared". Retrieved July 19, 2018.
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