Climate stage· The columns of time

MIS 10

350 ka → 337 ka

Marine isotope stage 10 is the glacial stage, from 350,000 to 337,000 years ago, during which this timeline opens.

Marine isotope stage 10, a glacial stage during which the chronological window of this timeline opens. The initial period of the history of the species therefore falls within a cold and not a temperate climatic regime.

What the evidence shows

Marine isotope stages are numbered from the present backwards, odd numbers corresponding to warm periods and even numbers to cold ones. They are established from the isotopic composition of oxygen in the calcareous shells of benthic foraminifera, microscopic organisms living on the ocean floor. The principle is that of fractionation by evaporation: a water molecule formed with the light isotope of oxygen evaporates slightly more readily than one formed with the heavy isotope, so that vapour, then snow and continental ice, are enriched in it, while the ocean that supplied them is correspondingly depleted. The isotopic measurement of a shell is therefore equivalent to a measurement of global ice volume. The LR04 stack, an average of 57 records distributed around the globe, converts these measurements into a continuous curve that divides the last three million years into stages. MIS 10 is among the coldest.

Bounds and conventions

The band is truncated at the left edge of the window, the stage beginning about 374,000 years ago, before this timeline starts. Stage boundaries are inflection points on a smoothed curve and not dated events; they vary by a few millennia between authors.

Glacial stage, truncated at the edge of the window: it begins around 374 ka.