Quaternary glaciation, also known as the Pleistocene glaciation, the current ice age or simply the ice age, refers to the period from 2.58 Ma (million years ago) to present, in which permanent ice sheets were established in Antarctica and perhaps Greenland, and fluctuating ice sheets have occurred elsewhere (for example, the Laurentide ice sheet). The major effects of the ice age were erosion and deposition of material over large parts of the continents, modification of river systems, creation of millions of lakes, changes in sea level, development of pluvial lakes far from the ice margins, isostatic adjustment of the crust, and abnormal winds. It affected oceans, flooding, and biological communities. The ice sheets themselves, by raising the albedo, effected a major feedback on climate cooling.

During the Quaternary Period, the total volume of land ice, sea level, and global temperature has fluctuated initially on 41,000- and more recently on 100,000-year time scales, as evidenced most clearly by ice cores for the past 800,000 years and marine sediment cores for the earlier period. Over the past 740,000 years there have been eight glacial cycles. The entire Quaternary Period, starting 2.58 Ma, is referred to as an ice age because at least one permanent large ice sheet — Antarctica — has existed continuously. There is uncertainty over how much of Greenland was covered by ice during the previous and earlier interglacials. During the colder episodes — referred to as glacial periods — large ice sheets also existed in Europe, North America, and Siberia. The shorter and warmer intervals between glacials are referred to as interglacials.

An ice age, or more precisely, a glacial age, is a period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers. Within a long-term ice age, individual pulses of cold climate are termed "glacial periods" (or alternatively "glacials" or "glaciations" or colloquially as "ice age"), and intermittent warm periods are called "interglacials". Glaciologically, ice age implies the presence of extensive ice sheets in the northern and southern hemispheres. By this definition, we are still in the ice age that began at the start of the Pleistocene epoch, because the Greenland and Antarctic ice sheets still exist.

More colloquially, "the Ice Age" refers to the most recent glacial period that peaked approximately 20,000 years ago, in which extensive ice sheets lay over large parts of the North American and Eurasian continents. This article will use the term ice age in the former, glaciological, sense: glacials for colder periods during ice ages and interglacials for the warmer periods.

Graham Hancock (born 2 August 1950 in Edinburgh, Scotland) is a British writer and journalist. Hancock specialises in unconventional theories involving ancient civilizations, stone monuments or megaliths, altered states of consciousness, ancient myths and astronomical/astrological data from the past. One of the main themes running through many of his books is the possible global connection with a "mother culture" from which he believes all ancient historical civilizations sprang.

Born in Edinburgh, Scotland, Hancock's formative years were spent in India, where his father worked as a surgeon. Having returned to the UK, he graduated from Durham University in 1973, receiving a First Class Honours degree in Sociology.

As a journalist, Hancock worked for many British papers, such as The Times, The Sunday Times, The Independent, and The Guardian. He was co-editor of New Internationalist magazine from 1976–1979 and East Africa correspondent of The Economist from 1981-1983.