Climate stage· The columns of time
MIS 10
350 ka → 337 ka
The frieze opens in the middle of a glacial stage, and that is the first thing it shows: this history begins in a cold world, not a temperate one.
What the evidence shows
Marine isotope stages are numbered from the present backwards, odd for warm and even for cold, and they are read from the oxygen locked in the shells of tiny organisms living on the deep sea floor. When ice sheets grow, they hold back the lighter isotope, and the ocean left behind becomes measurably heavier. The LR04 stack, which averages 57 such records from around the world, turns that chemistry into a curve, and it is the curve that divides the last three million years into stages. MIS 10 is one of the colder ones.
Bounds and conventions
The band is truncated at the left edge of the window: the stage actually begins around 374,000 years ago, well before this timeline starts. Stage boundaries are inflection points on a smoothed curve, not events, and different authors place them a few millennia apart.
A glacial stage, cut off at the edge of the window: it begins around 374 ka.