successive glaciations may wipe out evidence of their predecessors. Ice cores from continental ice accumulations also provide a complete record, but do not go as far back in time as marine data. Pollen data from lakes and bogs as well as loess profiles provided important land-based correlation data. The names system has mostly been phased out by professionals. It is now more common for researchers to refer to the periods by their marine isotopic stage number. For example, there are five Pleistocene glacial/interglacial cycles recorded in marine sediments during the last half million years, but only three classic glacials were originally recognized on land during that period (Mindel, Riss and Würm). Land-based evidence works acceptably well back as far as MIS 6, but it has been difficult to coordinate stages using just land-based evidence before that. Hence, the "names" system is incomplete and the land-based identifications of ice ages previous to that are somewhat conjectural. Nonetheless, land based data is essentially useful in discussing landforms, and correlating the known marine isotopic stage with them. Historical nomenclature in the Alps Biber (2.6–1.8 Ma, Gelasian) Biber-Danube interglacial (not in use) Danube (1.8–1.0 Ma, Calabrian) Danube-Gunz interglacial (not in use) Günz (1.0–0.4 Ma, MIS 21 – MIS 11 ?) Günz-Haslach interglacial (not in use) Haslach (seldom used) Haslach-Mindel interglacial (not in use) Mindel (MIS 12?, MIS 10) Mindel-Riss interglacial (MIS 9) Riss (MIS 8-6) Riss-Würm interglacial (MIS 5e) Würm (MIS 5d-2) Historical nomenclature in Great Britain and Ireland Bramertonian Stage Baventian Stage/Pre-Pastonian Pastonian Stage Beestonian stage Cromerian Stage (MIS 21-13 ?) Anglian Stage (MIS 12, perhaps also MIS 10 ?) Hoxnian Stage (MIS 11, perhaps also MIS 9 ?) Wolstonian Stage (MIS 8–6, perhaps also MIS 10–9 ?) Ipswichian interglacial (MIS 5e) Devensian glaciation (MIS 5d-2) Flandrian interglacial (MIS 1) Historical nomenclature in Northern Europe Pre-Tiglian Tiglian interglacial Eburonian Waalian interglacial Menapian glacial stage Bavelian Cromerian complex (MIS 21-13 ?) Elster glaciation (MIS 10, perhaps also MIS 12 ?) Holstein interglacial (MIS 9 ?) Saale glaciation (ended with MIS 6) Eem interglacial (MIS 5e) Weichsel glaciation (MIS 5d-2) Historical nomenclature in North America Nebraskan glaciation (replaced by Pre-Illinoian in modern scientific literature) Aftonian interglacial (replaced by Pre-Illinoian in modern scientific literature) Kansan glaciation (replaced by Pre-Illinoian in modern scientific literature) Yarmouthian (stage) (replaced by Pre-Illinoian in modern scientific literature) Illinoian stage (MIS 6) Sangamonian (MIS 5e, sometimes also 5d-5a) Wisconsin glaciation (MIS 4-2,