There have been five known ice ages in the Earths history, with the Earth experiencing the Quaternary Ice Age during the present time. Within ice ages, there exist periods of more severe conditions and more temperate referred to as glacial periods and interglacial periods. Based on climate proxies, paleoclimatologists study the different climate states originating from glaciation, however, this hypothesis is still controversial, though is growing in popularity among researchers as evidence in its favor has mounted. A minor series of glaciations occurred from 460 Ma to 430 Ma, there were extensive glaciations from 350 to 250 Ma. The current ice age, called the Quaternary glaciation, has more or less extensive glaciation on 40,000. Originally, the glacial and interglacial periods of the Quaternary Ice Age were named after characteristic geological features, and it is now more common for researchers to refer to the periods by their marine isotopic stage number. The marine record preserves all the past glaciations, the evidence is less complete because successive glaciations may wipe out evidence of their predecessors. Ice cores from continental ice accumulations also provide a complete record, pollen data from lakes and bogs as well as loess profiles provided important land-based correlation data. The names system has not been filled out since the technical discussion moved to using marine isotopic stage numbers. Land-based evidence works acceptably well back as far as MIS6, 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 useful in discussing landforms. The last glacial and interglacial periods of the Quaternary are named, from most recent to most distant, dates shown are in thousand years before present. Older periods of the Quaternary **Table data is based on Gibbard Figure 22.1, Ice cores are used to obtain a high resolution record of recent glaciation. It confirms the chronology of the marine isotopic stages, Ice core data shows that the last 400,000 years have consisted of short interglacials about as warm as the present alternated with much longer glacials substantially colder than present. Regional Glaciation of Kansas and Nebraska, work Group on Geospatial Analysis of Glaciated Environments. Pre-Wisconsin Glaciation of Central North America, Emporia KA, INQUA Commission on Glaciation, Emporia State University. Archived from the original on May 13,2008, global correlation tables for the Quaternary. Cambridge UK, Department of Geography, University of Cambridge, Gibbard, P. L. Boreham, S. Cohen, K. M
Showing the major glaciations (Ice Ages) in the context of Earth's entire existence.
500 million year record shows current and previous two major glacial periods