IUGS ratifies Holocene subdivision

On June 14, 2018, the Executive Committee of the International Union of Geological Sciences (IUGS) ratified the subdivision of the Holocene Series/Epoch as follows:

Lower/Early Holocene Subseries/Subepoch = Greenlandian Stage/Age with a base dated at 11,700 years b2k (before 2000 AD).  GSSP = NGRIP2 Greenland ice core.

Middle Holocene Subseries/Subepoch = Northgrippian Stage/Age with a base dated at 8236 years b2k. GSSP = NGRIP1 Greenland ice core.

Upper/Late Holocene Subseries/Subepoch = Meghalayan Stage/Age with a base dated at 4250 years b2k.  GSSP = a speleothem (specifically a stalagmite) from Mawmluh Cave, Meghalaya, northeast India.

Full details are published in Walker et al. (2018 online) in the IUGS journal Episodes, available here.

The above subdivision has no bearing on the Anthropocene, which remains an undefined unit under active investigation by the SQS Anthropocene Working Group.

ACKNOWLEDGEMENTS: These definitions originate with an initiative by Phil Gibbard (then Chair of SQS) in 2010 to establish a joint SQS/INQUA Working Group to examine the case for formal subdivision of the Holocene. Mike Walker led this Working Group and fronted the ensuing proposal (see also the discussion paper by M.J.C. Walker et al., 2012, Journal of Quaternary Science, 27: 649–659). The proposal was recommended  by the SQS voting membership in 2016 and approved by the ICS in 2018. It was ratified by the IUGS Executive Committee on 14 June 2018. The IUGS ratification letter is here. A letter from Allan Ashworth, President of INQUA, thanking INQUA for its support, is here.  David Harper, Chair of ICS, Phil Gibbard, Secretary General of ICS, and Stan Finney, Secretary General of the IUGS, all provided invaluable support during the long process of approval and ratification.