David d'Avray

Glossary of technical terms

Quaternary A period beginning 2.6 million years ago that includes the Pleistocene and Holocene epochs. The beginning of the Quaternary saw global cooling, glaciation of both poles and the appearance of the genus Homo. Pleistocene Beginning about 2.6 million years ago, the Pleistocene was a time marked by the periodic growth and decline of high-latitude ice sheets and glaciers. Late Pleistocene The late Pleistocene is made up of the last complete glacial–interglacial cycle, beginning about 126 ka with the onset of the last interglacial. LGM The last glacial maximum (26.5–19 ka). Formally defined as the latest period when global glaciers reached their maximum extent. The LGM was the driest of all glacials: forests shrank, deserts and ice sheets expanded, and sea levels fell to their lowest recorded levels, 135 m below modern sea level. Holocene The Holocene began at 11.7 ka with the resumption of rapid global warming after the last glacial episode. Although this was a comparatively stable period, it was not uniform and can be divided into three distinct phases: the early Holocene (11.7–8.0 ka), when vegetation and geomorphic systems were still adjusting to rapid postglacial changes in temperature, sea levels and rainfall; the mid-Holocene (8.0–4.0 ka); and the late Holocene (from 4.0 ka), which saw the onset of a drier, more variable climate dominated by the El Niño-Southern Oscillation (ENSO).