Timeline of glaciation

There have been four major periods of glaciation in the Earth's past. The second, and possibly most severe, is estimated to have occurred from 850 Ma to 635 Ma (million years ago, in the late Proterozoic Age) and it has been suggested that it produced a "Snowball Earth" in which the earth iced over completely. It has been suggested also that the end of this cold period was responsible for the subsequent Cambrian Explosion, a time of rapid diversification of multicelled life during the Cambrian era. However, this theory is still controversial. [van Andel, Tjeerd H. (1994) "New Views on an Old Planet: A History of Global Change" 2nd ed. Cambridge University Press, Cambridge, UK, ISBN 0521447550] [ [http://www.gsajournals.org/perlserv/?request=get-pdf&doi=10.1130%2FG23400A.1 Rieu, Ruben "et al." (2007) "Climatic cycles during a Neoproterozoic “snowball” glacial epoch" "Geology" 35(4): pp. 299–302] ]

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 seen more or less extensive glaciation on 40,000 and later, 100,000 year cycles. We are currently in an interglacial period, as the last glacial period ended about 10,000 years ago.

Major glacial periods in earth's history

**Table data is based on Gibbard Figure 22.1.

Ice core evidence of recent glaciation

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 (10,000 to 30,000 years) about as warm as the present alternated with much longer (70,000 to 90,000 years) glacials substantially colder than present. The new EPICA Antarctic ice core has revealed that between 400,000 and 780,000 years ago, interglacials occupied a considerably larger proportion of each glacial/interglacial cycle, but were not as warm as subsequent interglacials.

References

External Links

*Aber, J.S., 2006, [http://academic.emporia.edu/aberjame/ice/lec17/lec17.htm "Regional Glaciation of Kansas and Nebraska."] Emporia State University, Emporia, Kansas.
*anonymous, 2000, [http://www.emporia.edu/earthsci/gage/pre-wisc/pre-wisc.htm "Pre-Wisconsin Glaciation of Central North America."] Work Group on Geospatial Analysis of Glaciated Environments (GAGE), INQUA Commission on Glaciation, Emporia State University, Emporia, Kansas.
*anonymous, 2007, [http://www.quaternary.stratigraphy.org.uk/correlation/chart.html "Global correlation tables for the Quaternary."] Subcommission on Quaternary Stratigraphy, Department of Geography, University of Cambridge, Cambridge, England
*Gibbard, P.L., S. Boreham, K.M. Cohen and A. Moscariello, 2007, [http://www.quaternary.stratigraphy.org.uk/correlation/POSTERSTRAT_v2007b_small.jpg"Global chronostratigraphical correlation table for the last 2.7 million years v. 2007b."] , jpg version 844 KB. Subcommission on Quaternary Stratigraphy, Department of Geography, University of Cambridge, Cambridge, England
*Hambrey, M.J., and W.B. Harland, eds., 1981. [http://www.aber.ac.uk/~glawww/epgr.htm "Earth's pre-Pleistocene glacial record. "] Cambridge University Press, 1004 + xv pp. (book downloadable as series of PDF files)
*Silva, P.G. C. Zazo, T. Bardají, J. Baena, J. Lario y A. Rosas, 2007, [http://tierra.rediris.es/aequa/publicaciones_archivos/Tabla%20Cronoestigrafica.pdf "Tabla Cronoestratigráfica del Cuaternario aequa."] , PDF version 1.4 MB. asociación española para el estudio del cuaternario (aequa), Departamento de Geología, Universidad de Alcalá Madrid, Spain. (Corelation chart of European Quaternary and cultural stages and fossils)

See also

*Geologic timescale
*Glacial history of Minnesota
*Ice age
*Glacial period
*Last glacial period
*Varanger glaciation
*Brunhes-Matuyama reversal occurred about 780,000 years ago