Meghalayan

In the geologic time scale, the Meghalayan is the latest 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] Its Global Boundary Stratotype Section and Point (GSSP) is a Krem Mawmluh Cave formation in Meghalaya, northeast India.[6] 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.[7] The global auxiliary stratotype is an ice core from Mount Logan in Canada.[8]

Not to be confused with Meghalaya.

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	'Upper'	0.0117	0.129
		Chibanian or 'Middle'	0.129	0.774
		Calabrian	0.774	1.80
		Gelasian	1.80	2.58
Neogene	Pliocene	Piacenzian	2.58	3.60
Notes and references[1][2] Subdivision of the Quaternary Period according to the ICS, as of May 2019.[1] For the Holocene, dates are relative to the year 2000 (e.g. Greenlandian began 11,700 years before 2000). For the beginning 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.[1] 'Tarantian' is an informal, unofficial name proposed for a stage/age to replace the equally informal, unofficial 'Upper Pleistocene' subseries/subepoch. 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.

The Meghalayan begins 4,200 years BP, i.e., before 1950 (c. 2250 BC or 7750 HE),[9] leaving open room for the possible creation of the Anthropocene from 1950 forward.[10][11] 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.[9] "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.[11]

The age was officially ratified by the International Commission on Stratigraphy in July 2018 along with the Greenlandian and the Northgrippian.[6]

See also

• Geologic time scale
• 4.2 kiloyear event

References

1. Cohen, K. M.; Finney, S. C.; Gibbard, P. L.; Fan, J.-X. (January 2020). "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. Retrieved 23 February 2020.
2. Mike Walker; et al. (December 2018). "Formal ratification of the subdivision of the Holocene Series/Epoch (Quaternary System/Period)" (PDF). Episodes. Subcommission on Quaternary Stratigraphy (SQS). 41 (4): 213–223. doi:10.18814/epiiugs/2018/018016. Retrieved 11 November 2019. 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).
3. Cohen, Kim Mikkel, David A. T. Harper, Philip Leonard Gibbard, and Junxuan Fan. "The ICS International Chronostratigraphic Chart". International Commission on Stratigraphy. Archived from the original on 5 February 2020. Retrieved 15 July 2018.
4. "Scientists call our era the Meghalayan Age. Here's what the world was like when it began".
5. "'Meghalayan Age': Latest phase in Earth's history named after Indian state, began 4,200 years ago".
6. 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.
7. "'Meghalayan Age' makes the state a part of geologic history". Hindustan Times. 18 July 2018. Retrieved 26 July 2018.
8. Formal subdivision of the Holocene Series/Epoch
9. Jonathan Amos (18 July 2018). "Welcome to the Meghalayan Age - a new phase in history". BBC. Retrieved 19 July 2018.
10. International Commission on Stratigraphy. "Collapse of civilizations worldwide defines youngest unit of the Geologic Time Scale". News and Meetings. Retrieved 15 July 2018.
11. 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.

External links

• Chronostratigraphy benchmarks