Pleistocene Epoch


The Pleistocene ( , often referred to as the ''Ice Age'') is the geological
epoch In chronology 222px, Joseph Scaliger's ''De emendatione temporum'' (1583) began the modern science of chronology Chronology (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-E ...
that lasted from about 2,580,000 to 11,700 years ago, spanning the earth’s most recent period of repeated
glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age An ice age is a long period of reduction in the temperature of Earth Earth is the third planet from the Sun and the on ...
s. Before a change finally confirmed in 2009 by the
International Union of Geological Sciences The International Union of Geological Sciences (IUGS) is an international non-governmental organization File:Europe in a suitcase - UK.jpg, upright=1.3, alt=A roomful of people, Europe-Georgia Institute head George Melashvili addresses the audi ...
, the cutoff of the Pleistocene and the preceding
Pliocene The Pliocene ( ; also Pleiocene) epoch (geology), Epoch is the epoch in the geologic timescale that extends from 5.333 million to 2.58Before Present Before Present (BP) years is a time scale used mainly in archaeology Archaeology or archeology is the study of human activity through the recovery and analysis of material culture. Archaeology is often considered a branch of socio-cultural ...
(BP). Publications from earlier years may use either definition of the period. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the
Paleolithic The Paleolithic or Palaeolithic or Palæolithic (), also called the Old Stone Age (from Greek wikt:παλαιός, palaios - old, wikt:λίθος, lithos - stone), is a period in prehistory distinguished by the original development of stone too ...
age used in
archaeology Archaeology or archeology is the study of human activity through the recovery and analysis of material culture. Archaeology is often considered a branch of socio-cultural anthropology, but archaeologists also draw from biological, geological ...
. The name is a combination of
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages () ...
πλεῖστος (''pleīstos'', "most") and καινός (''kainós'' (
latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republic, it became the ...

ized as ''cænus''), "new". At the end of the preceding Pliocene, the previously isolated North and South American continents were joined by the
Isthmus of Panama The Isthmus of Panama ( es, Istmo de Panamá), also historically known as the Isthmus of Darien (), is the narrow strip of land that lies between the Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lamè Kara ...
, causing a faunal interchange between the two regions and changing
ocean circulation An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind Wind is the flow of gases on a large scale. On the surface of the Earth, wind consists of the bulk moveme ...
patterns, with the onset of glaciation in the Northern Hemisphere occurring around 2.7 million years ago. During the Early Pleistocene (2.58–0.8 Ma),
archaic humans A number of varieties of ''Homo ''Homo'' () is the genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classifi ...
of the genus ''
Homo ''Homo'' () is the genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, virus ...

'' originated in Africa and spread throughout
Afro-Eurasia Afro-Eurasia (or Afroeurasia, Field, Henry.The University of California African Expedition: I, Egypt, ''American Anthropologist,'' New Series Vol. 50, No. 3, Part 1 (Jul. - Sep., 1948), pp. 479-493. or Eurafrasia), nicknamed the World Island, ...

. The end of the Early Pleistocene is marked by the Mid-Pleistocene Transition, with the cyclicity of glacial cycles changing from 41,000 year cycles to 100,000 year cycles. The Late Pleistocene witnessed the spread of Early modern human, modern humans outside of Africa as well as the extinction of all other human species. Humans also History of Indigenous Australians#Migration to Australia, spread to the Australian continent and Settlement of the Americas, the Americas for the first time, co-incident with Quaternary extinction event, the extinction of most large bodied animals in these regions. The aridification and cooling trends of the preceding Neogene were continued in the Pleistocene. The climate was strongly variable depending on the glacial cycle, with the sea levels being up to 120 metres lower than present at peak glaciation, allowing the connection of Asia and North America via Beringia and the covering of most of northern North America by the Laurentide Ice Sheet, Laurentide ice sheet.


Charles Lyell introduced the term "Pleistocene" in 1839 to describe strata in Sicily that had at least 70% of their molluscan fauna still living today. This distinguished it from the older Pliocene, Pliocene Epoch, which Lyell had originally thought to be the youngest fossil rock layer. He constructed the name "Pleistocene" ("most new" or "newest") from the Greek language, Greek πλεῖστος (''pleīstos'', "most") and καινός (''kainós'' (
latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republic, it became the ...

ized as ''cænus''), "new"); this contrasts with the immediately preceding
Pliocene The Pliocene ( ; also Pleiocene) epoch (geology), Epoch is the epoch in the geologic timescale that extends from 5.333 million to 2.58


The Pleistocene has been dated from 2.580 million (±0.005) to 11,650 years BP with the end date expressed in radiocarbon years as 10,000 carbon-14 years BP. It covers most of the latest period of repeated
glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age An ice age is a long period of reduction in the temperature of Earth Earth is the third planet from the Sun and the on ...
, up to and including the Younger Dryas cold spell. The end of the Younger Dryas has been dated to about 9640 BC (11,654 calendar years BP). The end of the Younger Dryas is the official start of the current Holocene, Holocene Epoch. Although it is considered an epoch, the Holocene is not significantly different from previous interglacial intervals within the Pleistocene. In the International Commission on Stratigraphy, ICS timescale, the Pleistocene is divided into four stage (stratigraphy), stages or age (geology), ages, the Gelasian, Calabrian (stage), Calabrian, Chibanian (previously the unofficial "Middle Pleistocene"), and Late Pleistocene, Upper Pleistocene (unofficially the "Tarantian"). In addition to these international subdivisions, various regional subdivisions are often used. In 2009 the
International Union of Geological Sciences The International Union of Geological Sciences (IUGS) is an international non-governmental organization File:Europe in a suitcase - UK.jpg, upright=1.3, alt=A roomful of people, Europe-Georgia Institute head George Melashvili addresses the audi ...
(IUGS) confirmed a change in time period for the Pleistocene, changing the start date from 1.806 to 2.588 million years BP, and accepted the base of the Gelasian as the base of the Pleistocene, namely the base of the Monte San Nicola Global Boundary Stratotype Section and Point, GSSP. The start date has now been rounded down to 2.580 million years BP. The IUGS has yet to approve a type section, Global Boundary Stratotype Section and Point (GSSP), for the upper Pleistocene/Holocene boundary (''i.e.'' the upper boundary). The proposed section is the ''North Greenland Ice Core Project'' ice core 75° 06' N 42° 18' W. The lower boundary of the Pleistocene Series is formally defined Magnetostratigraphy, magnetostratigraphically as the base of the Matuyama (C2r) chronozone, isotopic stage 103. Above this point there are notable extinctions of the calcareous nanofossils: Discoaster, ''Discoaster pentaradiatus'' and ''Discoaster surculus''.Gradstein, Felix M.; Ogg, James G. and Smith, A. Gilbert (eds.) (2005) ''A Geologic Time Scale 2004'' Cambridge University Press, Cambridge, UK, p. 28, The Pleistocene covers the recent period of repeated glaciations. The name Plio-Pleistocene has, in the past, been used to mean the last ice age. Formerly, the boundary between the two epochs was drawn at the time when the foraminiferal species ''Hyalinea baltica'' first appeared in the marine section at La Castella, Calabria, Italy; however, the revised definition of the Quaternary, by pushing back the start date of the Pleistocene to 2.58 Ma, results in the inclusion of all the recent repeated glaciations within the Pleistocene. Radiocarbon dating is considered to be inaccurate beyond around 50,000 years ago. Marine isotope stages (MIS) derived from Oxygen isotopes are often used for giving approximate dates.


Pleistocene non-marine sediments are found primarily in fluvial deposit (geology), deposits, lakebeds, slope and loess deposits as well as in the large amounts of material moved about by glaciers. Less common are cave deposits, travertines and volcanic deposits (lavas, ashes). Pleistocene marine deposits are found primarily in shallow marine basins mostly (but with important exceptions) in areas within a few tens of kilometers of the modern shoreline. In a few geologically active areas such as the Southern California coast, Pleistocene marine deposits may be found at elevations of several hundred meters.

Paleogeography and climate

The modern continents were essentially at their present positions during the Pleistocene, the tectonic plate, plates upon which they sit probably having moved no more than relative to each other since the beginning of the period. In glacial periods, the sea level would drop by over during peak glaciation, exposing large areas of present continental shelf as dry land. According to Mark Lynas (through collected data), the Pleistocene's overall climate could be characterized as a continuous El Niño with trade winds in the south Pacific ocean, Pacific weakening or heading east, warm air rising near Peru, warm water spreading from the west Pacific and the Indian Ocean to the east Pacific, and other El Niño markers.

Glacial features

Pleistocene climate was marked by repeated glacial cycles in which continental glaciers pushed to the 40th parallel (latitude), parallel in some places. It is estimated that, at maximum glacial extent, 30% of the Earth's surface was covered by ice. In addition, a zone of permafrost stretched southward from the edge of the glacial sheet, a few hundred kilometres in North America, and several hundred in Eurasia. The mean annual temperature at the edge of the ice was ; at the edge of the permafrost, . Each glacial advance tied up huge volumes of water in continental ice sheets thick, resulting in temporary sea-level drops of or more over the entire surface of the Earth. During interglacial times, such as at present, drowned coastlines were common, mitigated by isostatic or other emergent motion of some regions. The effects of glaciation were global. Antarctica was ice-bound throughout the Pleistocene as well as the preceding Pliocene. The Andes were covered in the south by the Patagonian ice cap. There were glaciers in New Zealand and Tasmania. The current decaying glaciers of Mount Kenya, Mount Kilimanjaro, and the Ruwenzori Range in east and central Africa were larger. Glaciers existed in the mountains of Ethiopia and to the west in the Atlas mountains. In the northern hemisphere, many glaciers fused into one. The Cordilleran Ice Sheet covered the North American northwest; the east was covered by the Laurentide. The Fenno-Scandian ice sheet rested on northern Europe, including much of Great Britain; the Alpine ice sheet on the Alps. Scattered domes stretched across Siberia and the Arctic shelf. The northern seas were ice-covered. South of the ice sheets large lakes accumulated because outlets were blocked and the cooler air slowed evaporation. When the Laurentide Ice Sheet retreated, north-central North America was totally covered by Lake Agassiz. Over a hundred basins, now dry or nearly so, were overflowing in the North American west. Lake Bonneville, for example, stood where Great Salt Lake now does. In Eurasia, large lakes developed as a result of the runoff from the glaciers. Rivers were larger, had a more copious flow, and were Braided river, braided. African lakes were fuller, apparently from decreased evaporation. Deserts, on the other hand, were drier and more extensive. Rainfall was lower because of the decreases in oceanic and other evaporation. It has been estimated that during the Pleistocene, the East Antarctic Ice Sheet thinned by at least 500 meters, and that thinning since the Last Glacial Maximum is less than 50 meters and probably started after ca 14 ka.

Major events

Over 11 major glacial events have been identified, as well as many minor glacial events. A major glacial event is a general glacial excursion, termed a "glacial." Glacials are separated by "interglacials". During a glacial, the glacier experiences minor advances and retreats. The minor excursion is a "stadial"; times between stadials are "interstadials". These events are defined differently in different regions of the glacial range, which have their own glacial history depending on latitude, terrain and climate. There is a general correspondence between glacials in different regions. Investigators often interchange the names if the glacial geology of a region is in the process of being defined. However, it is generally incorrect to apply the name of a glacial in one region to another. For most of the 20th century only a few regions had been studied and the names were relatively few. Today the geologists of different nations are taking more of an interest in Pleistocene glaciology. As a consequence, the number of names is expanding rapidly and will continue to expand. Many of the advances and stadials remain unnamed. Also, the terrestrial evidence for some of them has been erased or obscured by larger ones, but evidence remains from the study of cyclical climate changes. The glacials in the following tables show ''historical'' usages, are a simplification of a much more complex cycle of variation in climate and terrain, and are generally no longer used. These names have been abandoned in favor of numeric data because many of the correlations were found to be either inexact or incorrect and more than four major glacials have been recognized since the historical terminology was established. Corresponding to the terms glacial and interglacial, the terms pluvial and interpluvial are in use (Latin: ''pluvia'', rain). A pluvial is a warmer period of increased rainfall; an interpluvial, of decreased rainfall. Formerly a pluvial was thought to correspond to a glacial in regions not iced, and in some cases it does. Rainfall is cyclical also. Pluvials and interpluvials are widespread. There is no systematic correspondence of pluvials to glacials, however. Moreover, regional pluvials do not correspond to each other globally. For example, some have used the term "Riss pluvial" in Egyptian contexts. Any coincidence is an accident of regional factors. Only a few of the names for pluvials in restricted regions have been stratigraphically defined.


The sum of transient factors acting at the Earth's surface is cyclical: climate, ocean currents and other movements, wind currents, temperature, etc. The waveform response comes from the underlying cyclical motions of the planet, which eventually drag all the transients into harmony with them. The repeated glaciations of the Pleistocene were caused by the same factors. The Mid-Pleistocene Transition, approximately one million years ago, saw a change from low-amplitude glacial cycles with a dominant periodicity of 41,000 years to asymmetric high-amplitude cycles dominated by a periodicity of 100,000 years. However, a 2020 study concluded that ice age terminations might have been influenced by Axial tilt, obliquity since the Mid-Pleistocene Transition, which caused stronger summers in the Northern Hemisphere.

Milankovitch cycles

Glaciation in the Pleistocene was a series of glacials and interglacials, stadials and interstadials, mirroring periodic changes in climate. The main factor at work in climate cycling is now believed to be Milankovitch cycles. These are periodic variations in regional and planetary solar radiation reaching the Earth caused by several repeating changes in the Earth's motion. Milankovitch cycles cannot be the sole factor responsible for the variations in climate since they explain neither the long term cooling trend over the Plio-Pleistocene, nor the millennial variations in the Greenland Ice Cores. Milankovitch pacing seems to best explain glaciation events with periodicity of 100,000, 40,000, and 20,000 years. Such a pattern seems to fit the information on climate change found in oxygen isotope cores.

Oxygen isotope ratio cycles

In Oxygen isotope ratio cycle, oxygen isotope ratio analysis, variations in the ratio of to (two isotopes of oxygen) by mass (measured by a mass spectrometer) present in the calcite of oceanic core samples is used as a diagnostic of ancient ocean temperature change and therefore of climate change. Cold oceans are richer in , which is included in the tests of the microorganisms (foraminifera) contributing the calcite. A more recent version of the sampling process makes use of modern glacial ice cores. Although less rich in than sea water, the snow that fell on the glacier year by year nevertheless contained and in a ratio that depended on the mean annual temperature. Temperature and climate change are cyclical when plotted on a graph of temperature versus time. Temperature coordinates are given in the form of a deviation from today's annual mean temperature, taken as zero. This sort of graph is based on another of isotope ratio versus time. Ratios are converted to a percentage difference from the ratio found in standard mean ocean water (SMOW). The graph in either form appears as a waveform with overtones. One half of a period is a Marine isotopic stage (MIS). It indicates a glacial (below zero) or an interglacial (above zero). Overtones are stadials or interstadials. According to this evidence, Earth experienced 102 MIS stages beginning at about 2.588 megaannum, Ma Before Present, BP in the Early Pleistocene Gelasian. Early Pleistocene stages were shallow and frequent. The latest were the most intense and most widely spaced. By convention, stages are numbered from the Holocene, which is MIS1. Glacials receive an even number; interglacials, odd. The first major glacial was MIS2-4 at about 85–11 ka BP. The largest glacials were 2, 6, 12, and 16; the warmest interglacials, 1, 5, 9 and 11. For matching of MIS numbers to named stages, see under the articles for those names.


Both marine and continental faunas were essentially modern but with many more large land mammals such as Mammoths, Mastodons, ''Diprotodon'', ''Smilodon'', tiger, lion, Aurochs, Short-faced bear, short-faced Arctotherium, bears, giant sloths, ''Gigantopithecus'' and others. Isolated landmasses such as Australia, Madagascar, New Zealand and islands in the Pacific saw the evolution of large birds and even reptiles such as the Elephant bird, moa, Haast's eagle, ''Quinkana'', ''Megalania'' and ''Meiolania''. The severe climatic changes during the Ice Age had major impacts on the fauna and flora. With each advance of the ice, large areas of the continents became totally depopulated, and plants and animals retreating southwards in front of the advancing glacier faced tremendous stress. The most severe stress resulted from drastic climatic changes, reduced living space, and curtailed food supply. A Holocene extinction event, major extinction event of large mammals (megafauna), which included mammoths, mastodons, Machairodontinae, saber-toothed cats, ''glyptodons'', the woolly rhinoceros, various giraffids, such as the Sivatherium; ground sloths, Irish elk, cave bears, Gomphotheres, dire wolves, and Arctodus, short-faced bears, began late in the Pleistocene and continued into the Holocene. Neanderthals also became extinct during this period. At the end of the last ice age, Poikilotherm, cold-blooded animals, smaller mammals like wood mouse, wood mice, migratory birds, and swifter animals like whitetail deer had replaced the megafauna and migrated north. Late Pleistocene bighorn sheep were more slender and had longer legs than their descendants today. Scientists believe that the change in predator fauna after the late Pleistocene extinctions resulted in a change of body shape as the species adapted for increased power rather than speed. The extinctions hardly affected Africa but were especially severe in North America where native horses and camels were wiped out. * Asian land mammal ages (ALMA) include Zhoukoudianian, Nihewanian, and Yushean. * European land mammal ages (ELMA) include the Villafranchian, Galerian Mammal Age, Galerian, and Aurelian Mammal Age, Aurelian *North American land mammal ages (NALMA) include Blancan (4.75–1.8), Irvingtonian (1.8–0.24) and Rancholabrean (0.24–0.01) in millions of years. The Blancan extends significantly back into the Pliocene. * South American land mammal ages (SALMA) include Uquian (2.5–1.5), Ensenadan (1.5–0.3) and Lujanian (0.3–0.01) in millions of years. The Uquian previously extended significantly back into the Pliocene, although the new definition places it entirely within the Pleistocene. In July 2018, a team of Russians, Russian scientists in collaboration with Princeton University announced that they had brought two female nematodes frozen in permafrost, from around 42,000 years ago, back to life. The two nematodes, at the time, were the oldest confirmed living animals on the planet. File:Ice age fauna of northern Spain - Mauricio Antón.jpg, Pleistocene of Northern Spain, including woolly mammoth, Panthera leo fossilis, cave lions eating a reindeer, Equus ferus ferus, tarpans, and woolly rhinoceros File:Pleistocene SA.jpg, Pleistocene of South America, including ''Megatherium'' and two ''Glyptodon''


The human evolution, evolution of anatomically modern humans took place during the Pleistocene. In the beginning of the Pleistocene ''Paranthropus'' species were still present, as well as early human ancestors, but during the lower Palaeolithic they disappeared, and the only hominin species found in fossilic records is ''Homo erectus'' for much of the Pleistocene. Acheulean Lithic analysis, lithics appear along with ''Homo erectus'', some 1.8 million years ago, replacing the more primitive Oldowan industry used by ''Australopithecus garhi, A. garhi'' and by the earliest species of ''Homo''. The Middle Paleolithic saw more varied speciation within ''Homo'', including the appearance of ''Homo sapiens'' about 200,000 years ago. According to mitochondrial timing techniques, anatomically modern humans, modern humans migrated from Africa after the Riss glaciation in the Middle Palaeolithic during the Eemian Stage, spreading all over the ice-free world during the late Pleistocene. A 2005 study posits that humans in this migration interbred with archaic human forms already outside of Africa by the late Pleistocene, incorporating archaic human genetic material into the modern human gene pool.

See also

* Climate change * Pleistocene megafauna * Pleistocene Park * Timeline of glaciation

Explanatory notes


* Ogg, Jim (June 2004)
"Overview of Global Boundary Stratotype Sections and Points (GSSP's)"
International Commission on Stratigraphy. Accessed 20 March 2019.

External links

Late Pleistocene environments of the southern high plains
1975, edited by Wendorf and Hester.
Pleistocene Microfossils: 50+ images of Foraminifera

Stepanchuk V.N., Sapozhnykov I.V. Nature and man in the pleistocene of Ukraine. 2010

Human Timeline (Interactive)
– Smithsonian Institution, Smithsonian, National Museum of Natural History (August 2016).
Pleistocene Park: Conservation Project to Restore a Pleistocene Ecology and Protect Permafrost Soils in Northern Siberia
{{Authority control Pleistocene, Articles which contain graphical timelines Geological epochs Quaternary geochronology