Sub-stage· The columns of time

Meghalayan

2,251 BCE → Today

The Meghalayan is the third and current age of the Holocene, opened 4,200 years ago by a two-century drought that coincided with the collapse of several early states.

Third and last age of the Holocene, currently in course, opened by the 4.2 ka event, a two-century drought episode contemporaneous with the collapse of several of the earliest state organisations.

What the evidence shows

A stalagmite from Mawmluh cave, in the state of Meghalaya, in north-eastern India, carries the chemical discontinuity that defines the base of this age, corresponding to an abrupt drying that occurred about 4,200 years ago. The same episode is recorded in archives from Mesopotamia to China, and it is contemporaneous with the collapse of the Akkadian empire, the end of the Egyptian Old Kingdom and disturbances in the Indus valley. Founding a stratigraphic limit on an event principally documented by human history is unusual and was contested from the moment of ratification.

Bounds and conventions

The age was ratified in 2018 and is subject to criticism. The procedure illuminates those criticisms: a working group of specialists proposes a section and a precise point and decides by vote, the competent subcommission votes in turn, then the International Commission on Stratigraphy, the International Union of Geological Sciences finally proceeding to ratification, that is, three successive votes by qualified majority followed by a ratification. A stratigraphic limit is therefore established by a deliberative procedure. The objections bore on the one hand on the less assured than apparent global synchrony of the drought, on the other on the holding of the vote while a competing proposal, the Anthropocene, was still under examination.

GSSP in a speleothem from Mawmluh cave, Meghalaya, 4,250 years b2k.