Although the name “Quaternary” has long been used by geologists to describe the period of time known as the Ice Ages, it was only in 2009 that the Quaternary Period was finally ratified as a formal subdivision of geological time by the International Union of Geological Sciences (IUGS).
The Quaternary Period, comprising the Pleistocene and Holocene Epochs, is marked by the waxing and waning of large continental ice sheets in the Northern Hemisphere during the last 2.6 million years. At the height of the most recent glacial period, about 20,000 years ago, large ice sheets covered Canada and northern USA, Scandinavia and northern Europe (including most of Britain) and Siberia - the Greenland Ice Sheet is the last remaining remnant of these once extensive Northern Hemisphere ice sheets. Small mountain glaciers also existed in the highest parts of Kosciuszko National Park and over large areas of central and western Tasmania, and with world sea levels up to 150 m lower than present, it would have been possible to walk across Bass Strait, Bering Strait and across the English Channel. Some 50 such glaciations, and subsequent interglaciations (such as the present, or Holocene interglaciation) occurred during the Quaternary, the period of time which also saw the rise and spread of the human species. During the last glaciation, iconic animal species, such as woolly mammoths, roamed across vast areas of the northern continents (Fig 1).
Ratification of the Quaternary came after intense lobbying by the International Union for Quaternary Research (INQUA), particularly over the last 5 years, and prolonged negotiations between INQUA and the IUGS commission that is responsible for managing the geological timescale, the International Commission for Stratigraphy (ICS) – see Pillans & Naish (2004), Aubry et al. (2005), Pillans (2007) and Ogg & Pillans (2008).
A paper describing the formal ratification of the Quaternary is about to be published (Gibbard et al. in press).
Aubry, M.P., Berggren, W.A., van Couvering, J., McGowran, B., Pillans, B., Hilgen, F., (2005) Quaternary: status, rank, definition, survival. Episodes, 28, 118-120.
Gibbard, P., Head, M.J., Walker, M., Alloway, B., Beu, A.G., Coltorti, M., Hall, V.M., Liu, J., Knudsen, K.-L., Van Kolfschoten, T., Litt, T., Marks, L., McManus, J., Partridge, T.C., Piotrowski, J.A., Pillans, B., Rousseau, D.-D., Suc, J.-P., Tesakov, A.S., Turner, C., Zazo, C., (in press) Formal ratification of the Quaternary System/Period and the Pleistocene Series/Epoch with a base at 2.588 Ma. Journal of Quaternary Science.
Ogg, J.G., Pillans, B., (2008) Establishing Quaternary as a formal international Period/System. Episodes, 31, 230-233.
Pillans, B., (2007) Defining the Quaternary: Where do we go from here? Stratigraphy, 4, 145-149.