Sub-stage· The columns of time
Meghalayan
2,251 BCE → Today
The age we are living in, opened by a two-century drought that several of the world's first states did not outlast.
What the evidence shows
A stalagmite from Mawmluh Cave, in the north-eastern Indian state of Meghalaya, carries the chemical shift that opens this age: an abrupt drying about 4,200 years ago. The same event appears in records from Mesopotamia to China, and it coincides with the collapse of the Akkadian empire, the end of the Egyptian Old Kingdom and disruption in the Indus valley. Pinning a geological boundary to an event best known from human history is unusual, and it was contested from the start.
Bounds and conventions
Ratified in 2018 and criticised ever since: partly because the drought's global synchrony is less certain than the definition implies, partly because the vote came while a rival proposal, the Anthropocene, was still being examined. The age is agreed; the reasoning behind it is not.
GSSP in a speleothem from Mawmluh Cave, Meghalaya, 4,250 years b2k.