Sub-stage· The columns of time

Greenlandian

11.7 ka → 6,237 BCE

The Greenlandian is the first age of the Holocene, from its base 11,700 years ago to the 8.2 ka cooling event.

First age of the Holocene, running from the base of the epoch to the 8.2 ka event. Agriculture spreads within it and the first permanent villages are established.

What the evidence shows

Its upper limit is the 8.2 ka event: an abrupt cooling and drying recorded throughout the northern hemisphere, attributed most probably to the sudden drainage of the glacial lakes Agassiz and Ojibway into the North Atlantic. This limit is one of the two reference points ratified in 2018, the lower limit being that of the Holocene itself. Both are defined in ice and not in rock, which is unusual for a geological age and carries a particular consequence: a stratigraphic limit is ordinarily fixed in rock, whose duration exceeds that of the period it defines, whereas an ice core flows, deforms at the base of the ice sheet and will eventually melt. These two reference points are therefore perishable and their preservation in cold storage forms part of their definition.

Bounds and conventions

The subdivision is ratified and official, but recent enough for its usefulness to be debated by some geologists. The debate bears on the relevance of dividing a single epoch into three ages and not on the reality of the events that fix its limits.

GSSP NGRIP2, 11,700 years b2k.