A time when there are ice sheets on the continents, within which there may be interglacial periods of milder climate. Ice ages last for some tens of millions of years, separated by intervals of c.150 million years. See Sutcliffe et al. (2000) Geol. 28, 11 on glaciation and Earth's orbit; Easterbrook (1963) GSA Bull. 75, 12 on Pleistocene glacial events and sea-level change; Gore et al. (2001) Geol. 29 on East Antarctica (ice free at the last glacial maximum), Bond et al. (1997) Science 278 on the Little Ice Age; and Barry (2006) PPG30, 3 on glacier retreat since then. A. Goudie (2000) is strong on the stratigraphic information from ocean and ice cores, and the causes of climate change.
Subjects: Earth Sciences and Geography.