Deep sea core samples have identified approximately 10 marine isotope stages (at least MIS 21 to MIS 11) during Gunz. Thus, there have probably been about 5 glacial cycles of varying intensity during Gunz. During Gunz the 41 000 year glacial cycle of previous stages (Biber and Danube) had been replaced by a dominance of a 100,000-year cycle (Mid-Pleistocene Transition). The most intense glacials of Gunz (MIS 16 and MIS 12) reached similar extents to those of the more recent Riss and Wurm glacials. These have not been easy to identify in the geological record of the Alps, but MIS 16 has been identified with the Don Glaciation of Eastern Europe. The strong glacial MIS 12 has been problematic, and has sometimes been identified with the Mindel glaciation, which would imply an end to Gunz already after MIS 13 (480 000 years ago).