Based on a lack of glacial evidence in Western Europe for the Middle Pleistocene (Ionian) before the Anglian glaciation, the Cromerian was originally thought to be a period without major glaciations. However, there is evidence for ice-rafting of material across the North Sea from this period. Investigations in the 1950s of oxygene isotopes in deep sea core samples revealed five glacial cycles during MIS 22 - MIS 13. The Mid-Pleistocene Transition to the 100,000 year glacial cycle became established during the Cromerian. Four of the glaciations (MIS 22, MIS 20, MIS 18, MIS 14) were moderate, probably involving low-land glaciation in Scandinavia, but not spreading to England and northern Germany. One of the glaciations, Marine Isotope Stage 16 (MIS 16), is globally as strong as the most recent glaciations, MIS 6 (main Saale) and MIS 2 (Weichsel/Devensian). There is plenty of evidence in Russia for a major glaciation during this stage, which is called the Don Glaciation and believed to correspond to MIS 16. It is not clear why western Europe seems so unaffected by this major glacial.Cambridge Quaternary Palaeoenvironments Group: Don Glaciation
