Stadials and interstadials are phases dividing the Quaternary period, i.e., the last 2.6 million years. Stadials are colder periods and interstadials are warmer. Each phase has a Marine Isotope Stage (MIS) number, working backwards from the present, with stadial having even numbers and interstadials odd numbers. Thus the current Holocene is MIS1 and the Last glacial period is MIS2. Stages are divided into warmer and colder intervals. MIS 5e (the Eemian), the hottest of the last million years, was the oldest interstadial of MIS5, with MIS3 and MIS1 being interstadials and MIS2 and MIS4 being colder stadials. In glacials a and c are stadials and b and d are warmer interstadials. Thus MIS 6a, 6c and 6e are stadials and 6b and 6d are interstadials.
Generally, stadials endure for a thousand years or less, interstadials for less than ten thousand years, interglacials for more than ten thousand and glacials for about one hundred thousand. The Bølling Oscillation and the Allerød Oscillation, where they are not clearly distinguished in the stratigraphy, are taken together to form the Bølling/Allerød interstadial, and dated from about 14,700 to 12,700 years before the present.
Greenland ice cores show 24 interstadials during the one hundred thousand years of the Wisconsin glaciation. Referred to as the Dansgaard-Oeschger events, they have been extensively studied, and in their northern European contexts are sometimes named after towns, such as the Brorup, the Odderade, the Oerel, the Glinde, the Hengelo, the Denekamp, etc.