Pleistocene — LLMpedia

Pleistocene
Scotese, Christopher R.; Wright, Nicky M. · CC BY 4.0 · source
Name	Pleistocene
Time start	2.58 Ma
Time end	0.0117 Ma
Preceding	Pliocene
Following	Holocene
Notable events	Quaternary glaciation, Last Glacial Maximum, Megafaunal extinction

Contents

Pleistocene

The Pleistocene was an epoch of the Neogene–Quaternary boundary characterized by cyclic glaciation events, marked changes in sea level, and major turnovers in terrestrial and marine biota. It witnessed the spread of archaic and modern Homo taxa, major dispersals across Eurasia, Africa, and the Americas, and profound impacts on iconic taxa such as Mammuthus, Smilodon, and Glyptodon. Key research institutions and projects including the Smithsonian Institution, the Natural History Museum, London, and the Max Planck Institute for Evolutionary Anthropology have driven synthesis across paleontology, stratigraphy, and archaeology.

Definition and Chronology

The epoch traditionally begins at the Pliocene–Pleistocene boundary (circa 2.58 million years ago) and ends at the start of the Holocene (circa 11.7 thousand years ago), framed within the Quaternary Period and the Cenozoic Era. Global chronostratigraphy relies on standards ratified by the International Commission on Stratigraphy and tied to marine isotope stages recorded in cores from the North Atlantic Ocean, Pacific Ocean, and Southern Ocean. Stratigraphic markers include shifts in benthic foraminifera assemblages identified by teams at the Lamont–Doherty Earth Observatory and the British Geological Survey. Correlation of terrestrial records employs tephrochronology from volcanic complexes such as Mount Vesuvius, Krakatoa, and Yellowstone Caldera and magnetostratigraphy first developed following work at the Geological Society of London.

Pleistocene geology exhibits cyclic deposition of tills, loess, and fluvial terraces documented in field studies by the United States Geological Survey and the Geological Survey of Canada. Orbital forcing described by Milutin Milanković explains pacing of glacial–interglacial cycles that are recorded in the marine isotope chronology refined by researchers at the National Oceanography Centre and the Ocean Drilling Program. Ice–albedo feedbacks affected regional climates from Greenland to Siberia and influenced vegetation zones first mapped by botanists associated with the Royal Botanic Gardens, Kew and the Missouri Botanical Garden. Pleistocene sea-level lowstands exposed continental shelves such as the Sunda Shelf and Beringia, facilitating faunal and hominin exchanges investigated by teams at the University of Cambridge and the University of Alaska Fairbanks.

Major Pleistocene glaciations produced continental ice sheets including the Laurentide Ice Sheet, Fennoscandian Ice Sheet, and the Cordilleran Ice Sheet, whose dynamics have been reconstructed using cosmogenic dating advanced at the Swiss Federal Institute of Technology Zurich and the University of Colorado Boulder. Episodes such as the Last Glacial Maximum and the Younger Dryas event are central to debates on abrupt climate change studied by researchers at the Woods Hole Oceanographic Institution and the Alfred Wegener Institute. Ice-margin fluctuations left geomorphic features like moraines at Lake Agassiz, drumlins in Ireland, and patterned ground across Antarctica and Greenland, catalogued by teams from the Scott Polar Research Institute and the British Antarctic Survey.

Pleistocene ecosystems ranged from steppe–tundra to temperate forests, hosting megafauna such as Mammuthus primigenius (woolly mammoth), Panthera leo spelaea (cave lion), Ursus spelaeus (cave bear), Gomphothere species, and giant ground sloths like Megatherium. Paleoecological reconstructions use pollen records from lake cores analyzed at the Max Planck Institute for Chemistry and macrofossil assemblages curated by the American Museum of Natural History and the Muséum national d'Histoire naturelle. Extinction patterns at the end of the epoch—affecting genera such as Equus, Camelops, and Stegodon—have been attributed variously to climatic shifts, human hunting as argued by proponents linked to the Clovis culture and critics associated with the Overkill hypothesis, and disease vectors studied by teams at the Royal Society and the National Academy of Sciences.

Hominin evolution during the Pleistocene includes speciation and dispersal of taxa such as Homo habilis, Homo erectus, Homo heidelbergensis, Homo neanderthalensis, and Homo sapiens, with key fossil sites at Olduvai Gorge, Dmanisi, Sima de los Huesos, Atapuerca, Denisova Cave, and Jebel Irhoud. Lithic industries from the Acheulean to the Upper Paleolithic are preserved at sites excavated by teams from the Institute of Archaeology, University College London and the Max Planck Institute for the Science of Human History. Genetic evidence from ancient DNA studies at the University of Copenhagen and the Wellcome Sanger Institute has clarified admixture events among Neanderthal and Denisovan lineages and modern humans during dispersals across Eurasia and into the Americas during episodes linked to Beringia migration corridors.

Regional records vary: European stratigraphy emphasizes sequences in the Loire Valley, Somme Valley, and the British Isles compiled by the Quaternary Research Association; North American records include the Great Lakes basin, Columbia River loess deposits, and Mojave Desert paleolakes studied by the Geological Society of America; African Pleistocene research focuses on the East African Rift, Olduvai Gorge, and the Wonderwerk Cave with contributions from the National Museums of Kenya and the South African Museum. In Asia, Pleistocene archives in Zagros Mountains, Himalaya, Sunda Shelf, and Yellow River terraces inform models developed at the Chinese Academy of Sciences and the Indian Council of Historical Research. Australasian records from Lake Eyre, Kakadu, and the Tasmanian sites have been advanced by the Australian National University and the Museum Victoria.

Category:Epochs