Pleistocene Marsupials
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The Pleistocene ( , often referred to as the ''
Ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gree ...
'') is the geological
epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...
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 that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...
s. Before a change was finally confirmed in 2009 by the
International Union of Geological Sciences The International Union of Geological Sciences (IUGS) is an international non-governmental organization devoted to international cooperation in the field of geology. About The IUGS was founded in 1961 and is a Scientific Union member of the Inte ...
, the cutoff of the Pleistocene and the preceding
Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Before Present Before Present (BP) years, or "years before present", is a time scale used mainly in archaeology, geology and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Becaus ...
(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 (), also called the Old Stone Age (from Greek: παλαιός ''palaios'', "old" and λίθος ''lithos'', "stone"), is a period in human prehistory that is distinguished by the original development of stone too ...
age used in
archaeology Archaeology or archeology is the scientific study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, sites, and cultural landscap ...
. The name is a combination of
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
grc, label=none, πλεῖστος, pleīstos, most and grc, label=none, καινός, kainós (
latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
ized as ), '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 and the Pacific Ocean, linking North and South America. It contains the country ...
, 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, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, s ...
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'' are grouped into the broad category of archaic humans in the period that precedes and is contemporary to the emergence of the earliest early modern humans (''Homo sapiens'') around 300 ka. Omo-Kibish I (Omo I) f ...
of the genus ''
Homo ''Homo'' () is the genus that emerged in the (otherwise extinct) genus ''Australopithecus'' that encompasses the extant species ''Homo sapiens'' ( modern humans), plus several extinct species classified as either ancestral to or closely relate ...
'' originated in Africa and spread throughout
Afro-Eurasia Afro-Eurasia (also Afroeurasia, Eurafrasia or the Old World) is a landmass comprising the continents of Africa, Asia, and Europe. The terms are compound words of the names of its constituent parts. Its mainland is the largest and most populou ...
. The end of the Early Pleistocene is marked by the
Mid-Pleistocene Transition The Mid-Pleistocene Transition (MPT), also known as the Mid-Pleistocene Revolution (MPR), is a fundamental change in the behaviour of glacial cycles during the Quaternary glaciations. The transition happened approximately 1.25–0.7 milli ...
, with the cyclicity of glacial cycles changing from 41,000-year cycles to asymmetric 100,000-year cycles, making the climate variation more extreme. The
Late Pleistocene The Late Pleistocene is an unofficial Age (geology), age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a Stratigraphy, stratigraphic perspective. It is intended to be the fourth division of ...
witnessed the spread of
modern humans Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, an ...
outside of Africa as well as the extinction of all other human species. Humans also spread to the Australian continent and
the Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North America, North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. ...
for the first time, co-incident with the extinction of most large bodied animals in these regions. The aridification and cooling trends of the preceding
Neogene The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period Mya. ...
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 Beringia is defined today as the land and maritime area bounded on the west by the Lena River in Russia; on the east by the Mackenzie River in Canada; on the north by 72 degrees north latitude in the Chukchi Sea; and on the south by the tip ...
and the covering of most of northern North America by the
Laurentide Ice Sheet The Laurentide Ice Sheet was a massive sheet of ice that covered millions of square miles, including most of Canada and a large portion of the Northern United States, multiple times during the Quaternary glacial epochs, from 2.58 million years a ...
.


Etymology

Charles Lyell Sir Charles Lyell, 1st Baronet, (14 November 1797 – 22 February 1875) was a Scottish geologist who demonstrated the power of known natural causes in explaining the earth's history. He is best known as the author of ''Principles of Geolo ...
introduced the term "Pleistocene" in 1839 to describe strata in
Sicily (man) it, Siciliana (woman) , population_note = , population_blank1_title = , population_blank1 = , demographics_type1 = Ethnicity , demographics1_footnotes = , demographi ...
that had at least 70% of their molluscan fauna still living today. This distinguished it from the older
Pliocene Epoch The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
πλεῖστος (''pleīstos'', "most") and καινός (''kainós'' (
latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
ized as ''cænus''), "new"); this contrasts with the immediately preceding
Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...
("wholly new" or "entirely new", from ὅλος (''hólos'', "whole") and ''kainós'')
epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...
, which extends to the present time.


Dating

The Pleistocene has been dated from 2.580 million (±0.005) to 11,650 years BP with the end date expressed in
radiocarbon year Radiocarbon dating measurements produce ages in "radiocarbon years", which must be converted to calendar ages by a process called calibration. Calibration is needed because the atmospheric / ratio, which is a key element in calculating radiocarbo ...
s as 10,000
carbon-14 Carbon-14, C-14, or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Its presence in organic materials is the basis of the radiocarbon dating method pioneered by Willard Libby and coll ...
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 that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...
, up to and including the
Younger Dryas The Younger Dryas (c. 12,900 to 11,700 years BP) was a return to glacial conditions which temporarily reversed the gradual climatic warming after the Last Glacial Maximum (LGM, c. 27,000 to 20,000 years BP). The Younger Dryas was the last stage ...
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 Epoch The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...
. Although it is considered an epoch, the Holocene is not significantly different from previous interglacial intervals within the Pleistocene. In the ICS timescale, the Pleistocene is divided into four
stages Stage or stages may refer to: Acting * Stage (theatre), a space for the performance of theatrical productions * Theatre, a branch of the performing arts, often referred to as "the stage" * ''The Stage'', a weekly British theatre newspaper * S ...
or
ages Ages may refer to: *Advanced glycation end-products, known as AGEs *Ages, Kentucky, census-designated place, United States * ''Ages'' (album) by German electronic musician Edgar Froese *The geologic time scale, a system of chronological measuremen ...
, the
Gelasian The Gelasian is an age (geology), age in the international geologic timescale or a stage (stratigraphy), stage in chronostratigraphy, being the earliest or lowest subdivision of the Quaternary Period/System and Pleistocene Epoch/Series. It spans ...
, Calabrian,
Chibanian The Chibanian, widely known by its previous designation of Middle Pleistocene, is an Age (geology), age in the international geologic timescale or a Stage (stratigraphy), stage in chronostratigraphy, being a division of the Pleistocene Epoch withi ...
(previously the unofficial "Middle Pleistocene"), and
Upper Pleistocene The Late Pleistocene is an unofficial age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a stratigraphic perspective. It is intended to be the fourth division of the Pleistocene Epoch within ...
(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 devoted to international cooperation in the field of geology. About The IUGS was founded in 1961 and is a Scientific Union member of the Inte ...
(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 The Gelasian is an age (geology), age in the international geologic timescale or a stage (stratigraphy), stage in chronostratigraphy, being the earliest or lowest subdivision of the Quaternary Period/System and Pleistocene Epoch/Series. It spans ...
as the base of the Pleistocene, namely the base of the Monte San Nicola
GSSP A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. The effort to define GSSPs is conducted b ...
. The start date has now been rounded down to 2.580 million years BP. The IUGS has yet to approve a
type section A stratotype or type section in geology is the physical location or outcrop of a particular reference exposure of a stratigraphic sequence or stratigraphic boundary. If the stratigraphic unit is layered, it is called a stratotype, whereas the stan ...
,
Global Boundary Stratotype Section and Point A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. The effort to define GSSPs is conducted b ...
(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 magnetostratigraphically as the base of the Matuyama (C2r)
chronozone A chronozone or chron is a unit in chronostratigraphy, defined by events such as geomagnetic reversals (magnetozones), or based on the presence of specific fossils (biozone or biochronozone). According to the International Commission on Stratig ...
, isotopic stage 103. Above this point there are notable extinctions of the calcareous
nanofossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...
s: ''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 The Plio-Pleistocene is an informally described geological pseudo-period, which begins about 5 million years ago (Mya) and, drawing forward, combines the time ranges of the formally defined Pliocene and Pleistocene epochs—marking from about 5&nbs ...
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 The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...
, 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 stage Marine isotope stages (MIS), marine oxygen-isotope stages, or oxygen isotope stages (OIS), are alternating warm and cool periods in the Earth's paleoclimate, deduced from oxygen isotope data reflecting changes in temperature derived from data ...
s (MIS) derived from Oxygen isotopes are often used for giving approximate dates.


Deposits

Pleistocene non-marine
sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...
s are found primarily in fluvial deposits, lakebeds, slope and
loess Loess (, ; from german: Löss ) is a clastic, predominantly silt-sized sediment that is formed by the accumulation of wind-blown dust. Ten percent of Earth's land area is covered by loess or similar deposits. Loess is a periglacial or aeolian ...
deposits as well as in the large amounts of material moved about by glaciers. Less common are
cave A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can refer to smaller openings such as sea ...
deposits,
travertine Travertine ( ) is a form of terrestrial limestone deposited around mineral springs, especially hot springs. It often has a fibrous or concentric appearance and exists in white, tan, cream-colored, and even rusty varieties. It is formed by a pro ...
s 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 kilometres of the modern shoreline. In a few geologically active areas such as the
Southern California Southern California (commonly shortened to SoCal) is a geographic and Cultural area, cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most po ...
coast, Pleistocene marine deposits may be found at elevations of several hundred metres.


Paleogeography and climate

The modern
continent A continent is any of several large landmasses. Generally identified by convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continents. Ordered from largest in area to smallest, these seven ...
s were essentially at their present positions during the Pleistocene, the 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 A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...
as dry land. According to
Mark Lynas Mark Lynas (born 1973) is a British author and journalist whose work is focused on environmentalism and climate change. He is a contributor to ''New Statesman'', ''The Ecologist'', ''Granta ''and ''Geographical ''magazines, and ''The Guardian'' ...
(through collected data), the Pleistocene's overall climate could be characterised as a continuous
El Niño El Niño (; ; ) is the warm phase of the El Niño–Southern Oscillation (ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (approximately between the International Date L ...
with
trade winds The trade winds or easterlies are the permanent east-to-west prevailing winds that flow in the Earth's equatorial region. The trade winds blow mainly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisph ...
in the south
Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
weakening or heading east, warm air rising near
Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...
, warm water spreading from the west Pacific and the
Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...
to the east Pacific, and other El Niño markers.


Glacial features

Pleistocene climate was marked by repeated glacial cycles in which
continental glacier In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are in Antarctica and Greenland; during the Last Glacial Period at Las ...
s pushed to the 40th
parallel Parallel is a geometric term of location which may refer to: Computing * Parallel algorithm * Parallel computing * Parallel metaheuristic * Parallel (software), a UNIX utility for running programs in parallel * Parallel Sysplex, a cluster of IBM ...
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 Permafrost is ground that continuously remains below 0 °C (32 °F) for two or more years, located on land or under the ocean. Most common in the Northern Hemisphere, around 15% of the Northern Hemisphere or 11% of the global surface ...
stretched southward from the edge of the glacial sheet, a few hundred kilometres in
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
, and several hundred in
Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...
. 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 coastline Submergent coastlines or drowned coastlines are stretches along the coast that have been inundated by the sea by a relative rise in sea levels from either isostacy or eustacy. Submergent coastline are the opposite of emergent coastlines, which ...
s were common, mitigated by isostatic or other emergent motion of some regions. The effects of glaciation were global.
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...
was ice-bound throughout the Pleistocene as well as the preceding Pliocene. The
Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...
were covered in the south by the
Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...
n ice cap. There were glaciers in
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
and
Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...
. The current decaying glaciers of
Mount Kenya Mount Kenya (Kikuyu: ''Kĩrĩnyaga'', Kamba, ''Ki Nyaa'') is the highest mountain in Kenya and the second-highest in Africa, after Kilimanjaro. The highest peaks of the mountain are Batian (), Nelion () and Point Lenana (). Mount Kenya is locat ...
,
Mount Kilimanjaro Mount Kilimanjaro () is a dormant volcano in Tanzania. It has three volcanic cones: Kibo, Mawenzi, and Shira. It is the highest mountain in Africa and the highest free-standing mountain above sea level in the world: above sea level and ab ...
, and the
Ruwenzori Range The Ruwenzori, also spelled Rwenzori and Rwenjura, are a range of mountains in eastern equatorial Africa, located on the border between Uganda and the Democratic Republic of the Congo. The highest peak of the Ruwenzori reaches , and the range' ...
in east and central Africa were larger. Glaciers existed in the mountains of
Ethiopia Ethiopia, , om, Itiyoophiyaa, so, Itoobiya, ti, ኢትዮጵያ, Ítiyop'iya, aa, Itiyoppiya officially the Federal Democratic Republic of Ethiopia, is a landlocked country in the Horn of Africa. It shares borders with Eritrea to the ...
and to the west in the
Atlas mountains The Atlas Mountains are a mountain range in the Maghreb in North Africa. It separates the Sahara Desert from the Mediterranean Sea and the Atlantic Ocean; the name "Atlantic" is derived from the mountain range. It stretches around through Moroc ...
. 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 Laurentide Ice Sheet was a massive sheet of ice that covered millions of square miles, including most of Canada and a large portion of the Northern United States, multiple times during the Quaternary glacial epochs, from 2.58 million years a ...
. The
Fenno-Scandian ice sheet The Weichselian glaciation was the last glacial period and its associated glaciation in northern parts of Europe. In the Alpine region it corresponds to the Würm glaciation. It was characterized by a large ice sheet (the Fenno-Scandian ice sheet) ...
rested on
northern Europe The northern region of Europe has several definitions. A restrictive definition may describe Northern Europe as being roughly north of the southern coast of the Baltic Sea, which is about 54th parallel north, 54°N, or may be based on other g ...
, including much of Great Britain; the
Alpine ice sheet Alpine may refer to any mountainous region. It may also refer to: Places Europe * Alps, a European mountain range ** Alpine states, which overlap with the European range Australia * Alpine, New South Wales, a Northern Village * Alpine National Pa ...
on the
Alps The Alps () ; german: Alpen ; it, Alpi ; rm, Alps ; sl, Alpe . are the highest and most extensive mountain range system that lies entirely in Europe, stretching approximately across seven Alpine countries (from west to east): France, Sw ...
. Scattered domes stretched across
Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part of ...
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 Lake Agassiz was a large glacial lake in central North America. Fed by glacial meltwater at the end of the last glacial period, its area was larger than all of the modern Great Lakes combined. First postulated in 1823 by William H. Keating, it ...
. Over a hundred basins, now dry or nearly so, were overflowing in the North American west.
Lake Bonneville Lake Bonneville was the largest Late Pleistocene paleolake in the Great Basin of western North America. It was a pluvial lake that formed in response to an increase in precipitation and a decrease in evaporation as a result of cooler temperature ...
, for example, stood where
Great Salt Lake The Great Salt Lake is the largest saltwater lake in the Western Hemisphere and the eighth-largest terminal lake in the world. It lies in the northern part of the U.S. state of Utah and has a substantial impact upon the local climate, particula ...
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 Braided is a musical group consisting of Casey LeBlanc, Ashley Leitão, and Amber Fleury, who all competed on the third season of '' Canadian Idol'' in 2005. They are the third music group to come from an Idol show in the world, after Young Div ...
. 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 The East Antarctic Ice Sheet (EAIS) is one of two large ice sheets in Antarctica, and the largest on the entire planet. The EAIS lies between 45° west and 168° east longitudinally. The EAIS holds enough ice to raise global sea levels by and ...
thinned by at least 500 meters, and that thinning since the
Last Glacial Maximum The Last Glacial Maximum (LGM), also referred to as the Late Glacial Maximum, was the most recent time during the Last Glacial Period that ice sheets were at their greatest extent. Ice sheets covered much of Northern North America, Northern Eur ...
is less than 50 meters and probably started after ca 14 ka.


Major events

During the 2.5 million years of the Pleistocene, numerous cold phases called
glacials A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate bet ...
(
Quaternary ice age The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million year ...
), or significant advances of continental ice sheets, in Europe and North America, occurred at intervals of approximately 40,000 to 100,000 years. The long glacial periods were separated by more temperate and shorter
interglacial An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene in ...
s which lasted about 10,000–15,000 years. The last cold episode of the last glacial period ended about 10,000 years ago. 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 favour of numeric data because many of the correlations were found to be either inexact or incorrect and more than four major glacials have been recognised 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.


Palaeocycles

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 The Mid-Pleistocene Transition (MPT), also known as the Mid-Pleistocene Revolution (MPR), is a fundamental change in the behaviour of glacial cycles during the Quaternary glaciations. The transition happened approximately 1.25–0.7 milli ...
, 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
obliquity In astronomy, axial tilt, also known as obliquity, is the angle between an object's rotational axis and its orbital axis, which is the line perpendicular to its orbital plane; equivalently, it is the angle between its equatorial plane and orbit ...
since the Mid-Pleistocene Transition, which caused stronger summers in the
Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...
.


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 Milankovitch cycles describe the collective effects of changes in the Earth's movements on its climate over thousands of years. The term was coined and named after Serbian geophysicist and astronomer Milutin Milanković. In the 1920s, he hypot ...
. 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 analysis, variations in the ratio of to (two
isotopes Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...
of
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
) by
mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different elementar ...
(measured by a
mass spectrometer Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a ''mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used ...
) present in the
calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...
of oceanic
core sample A core sample is a cylindrical section of (usually) a naturally-occurring substance. Most core samples are obtained by drilling with special drills into the substance, such as sediment or rock, with a hollow steel tube, called a core drill. The h ...
s 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 Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular Ectoplasm (cell biology), ectoplasm for catching food and ot ...
) 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 In electronics, acoustics, and related fields, the waveform of a signal is the shape of its graph as a function of time, independent of its time and magnitude scales and of any displacement in time.David Crecraft, David Gorham, ''Electronic ...
with
overtones An overtone is any resonant frequency above the fundamental frequency of a sound. (An overtone may or may not be a harmonic) In other words, overtones are all pitches higher than the lowest pitch within an individual sound; the fundamental i ...
. One half of a period is a
Marine isotopic stage Marine isotope stages (MIS), marine oxygen-isotope stages, or oxygen isotope stages (OIS), are alternating warm and cool periods in the Earth's paleoclimate, deduced from oxygen isotope data reflecting changes in temperature derived from data f ...
(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 Ma BP in the Early Pleistocene
Gelasian The Gelasian is an age (geology), age in the international geologic timescale or a stage (stratigraphy), stage in chronostratigraphy, being the earliest or lowest subdivision of the Quaternary Period/System and Pleistocene Epoch/Series. It spans ...
. 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.


Fauna

Both marine and continental faunas were essentially modern but with many more large land mammals such as
Mammoth A mammoth is any species of the extinct elephantid genus ''Mammuthus'', one of the many genera that make up the order of trunked mammals called proboscideans. The various species of mammoth were commonly equipped with long, curved tusks and, ...
s,
Mastodon A mastodon ( 'breast' + 'tooth') is any proboscidean belonging to the extinct genus ''Mammut'' (family Mammutidae). Mastodons inhabited North and Central America during the late Miocene or late Pliocene up to their extinction at the end of th ...
s, ''
Diprotodon ''Diprotodon'' (Ancient Greek: "two protruding front teeth") is an extinct genus of marsupial from the Pleistocene of Australia, containing one species, ''D. optatum''. The earliest finds date to 1.77 million to 780,000 years ago, but most speci ...
'', ''
Smilodon ''Smilodon'' is a genus of the extinct machairodont subfamily of the felids. It is one of the most famous prehistoric mammals and the best known saber-toothed cat. Although commonly known as the saber-toothed tiger, it was not closely related ...
'',
tiger The tiger (''Panthera tigris'') is the largest living cat species and a member of the genus '' Panthera''. It is most recognisable for its dark vertical stripes on orange fur with a white underside. An apex predator, it primarily preys on u ...
,
lion The lion (''Panthera leo'') is a large Felidae, cat of the genus ''Panthera'' native to Africa and India. It has a muscular, broad-chested body; short, rounded head; round ears; and a hairy tuft at the end of its tail. It is sexually dimorphi ...
,
Aurochs The aurochs (''Bos primigenius'') ( or ) is an extinct cattle species, considered to be the wild ancestor of modern domestic cattle. With a shoulder height of up to in bulls and in cows, it was one of the largest herbivores in the Holocen ...
, short-faced
bears Bears are carnivoran mammals of the family Ursidae. They are classified as caniforms, or doglike carnivorans. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats throughout the North ...
,
giant sloth Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. The term is used to refer to all extinct sloths because of the large size of the earliest forms discovered, compared to existing tree sloths. The Caribbea ...
s, ''
Gigantopithecus ''Gigantopithecus'' ( ; ) is an extinct genus of ape from roughly 2 million to 350,000 years ago during the Early Pleistocene, Early to Middle Pleistocene of southern China, represented by one species, ''Gigantopithecus blacki''. Potential identi ...
'' and others. Isolated landmasses such as
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
,
Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...
,
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
and islands in the Pacific saw the evolution of large birds and even reptiles such as the
Elephant bird Elephant birds are members of the extinct ratite family Aepyornithidae, made up of flightless birds that once lived on the island of Madagascar. They are thought to have become extinct around 1000-1200 CE, probably as a result of human activity. ...
,
moa Moa are extinct giant flightless birds native to New Zealand. The term has also come to be used for chicken in many Polynesian cultures and is found in the names of many chicken recipes, such as Kale moa and Moa Samoa. Moa or MOA may also refe ...
,
Haast's eagle Haast's eagle (''Hieraaetus moorei'') is an extinct species of eagle that once lived in the South Island of New Zealand, commonly accepted to be the pouakai of Māori legend.Quinkana ''Quinkana'' is an extinct genus of mekosuchine crocodylians that lived in Australia from about 28 million to about 10,000 years ago. Most attributed specimens have been found in Queensland. It is speculated to have been one of the top predators ...
'', ''
Megalania Megalania (''Varanus priscus'') is an extinct species of giant monitor lizard, part of the megafaunal assemblage that inhabited Australia during the Pleistocene. It is the largest terrestrial lizard known to have existed, reaching an estimated ...
'' and ''
Meiolania ''Meiolania'' ("small roamer") is an extinct genus of meiolaniid stem-turtle native to Australasia from the Middle Miocene to Late Pleistocene and possibly Holocene. It is best known from fossils found on Lord Howe Island, though fossils are know ...
''. 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 major extinction event of large
mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
s (
megafauna In terrestrial zoology, the megafauna (from Greek μέγας ''megas'' "large" and New Latin ''fauna'' "animal life") comprises the large or giant animals of an area, habitat, or geological period, extinct and/or extant. The most common threshold ...
), which included
mammoth A mammoth is any species of the extinct elephantid genus ''Mammuthus'', one of the many genera that make up the order of trunked mammals called proboscideans. The various species of mammoth were commonly equipped with long, curved tusks and, ...
s,
mastodon A mastodon ( 'breast' + 'tooth') is any proboscidean belonging to the extinct genus ''Mammut'' (family Mammutidae). Mastodons inhabited North and Central America during the late Miocene or late Pliocene up to their extinction at the end of th ...
s,
saber-toothed cats Sabretooth or sabertooth may refer to: Animals * Saber-toothed cat, several prehistoric felines ** ''Smilodon'', a prehistoric genus of felidae * Sabertooth fish, a deep-sea fish found in the tropics ** Sabre-toothed blenny, ''Aspidontus taenia ...
, ''
glyptodon ''Glyptodon'' (from Greek for 'grooved or carved tooth': γλυπτός 'sculptured' and ὀδοντ-, ὀδούς 'tooth') is a genus of glyptodont (an extinct group of large, herbivorous armadillos) that lived from the Pleistocene, around 2.5 ...
s'', the
woolly rhinoceros The woolly rhinoceros (''Coelodonta antiquitatis'') is an extinct species of rhinoceros that was common throughout Europe and Asia during the Pleistocene epoch and survived until the end of the last glacial period. The woolly rhinoceros was a me ...
, various
giraffid The Giraffidae are a family of ruminant artiodactyl mammals that share a common ancestor with deer and bovids. This family, once a diverse group spread throughout Eurasia and Africa, presently comprises only two extant genera, the giraffe (one or ...
s, such as the
Sivatherium ''Sivatherium'' ("Shiva's beast", from Shiva and ''therium'', Latinized form of Ancient Greek θηρίον -'' thēríon'') is an extinct genus of giraffids that ranged throughout Africa to the Indian subcontinent. The species ''Sivatherium giga ...
;
ground sloth Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. The term is used to refer to all extinct sloths because of the large size of the earliest forms discovered, compared to existing tree sloths. The Caribbe ...
s,
Irish elk The Irish elk (''Megaloceros giganteus''), also called the giant deer or Irish deer, is an extinct species of deer in the genus ''Megaloceros'' and is one of the largest deer that ever lived. Its range extended across Eurasia during the Pleisto ...
,
cave bear The cave bear (''Ursus spelaeus'') is a prehistoric species of bear that lived in Europe and Asia during the Pleistocene and became extinct about 24,000 years ago during the Last Glacial Maximum. Both the word "cave" and the scientific name ' ...
s,
Gomphothere Gomphotheres are any members of the diverse, extinct taxonomic family Gomphotheriidae. Gomphotheres were elephant-like proboscideans, but do not belong to the family Elephantidae. They were widespread across Afro-Eurasia and North America during ...
s,
dire wolves The dire wolf (''Aenocyon dirus'' ) is an extinct canine. It is one of the most famous prehistoric carnivores in North America, along with its extinct competitor ''Smilodon''. The dire wolf lived in the Americas and eastern Asia during the L ...
, and short-faced bears, began late in the Pleistocene and continued into the Holocene.
Neanderthal Neanderthals (, also ''Homo neanderthalensis'' and erroneously ''Homo sapiens neanderthalensis''), also written as Neandertals, are an extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ago. While th ...
s also became extinct during this period. At the end of the last ice age, cold-blooded animals, smaller mammals like
wood mice The wood mouse (''Apodemus sylvaticus'') is a murid rodent native to Europe and northwestern Africa. It is closely related to the yellow-necked mouse (''Apodemus flavicollis'') but differs in that it has no band of yellow fur around the neck, h ...
, migratory birds, and swifter animals like
whitetail deer The white-tailed deer (''Odocoileus virginianus''), also known as the whitetail or Virginia deer, is a medium-sized deer native to North America, Central America, and South America as far south as Peru and Bolivia. It has also been introduced t ...
had replaced the megafauna and migrated north. Late Pleistocene
bighorn sheep The bighorn sheep (''Ovis canadensis'') is a species of sheep native to North America. It is named for its large horns. A pair of horns might weigh up to ; the sheep typically weigh up to . Recent genetic testing indicates three distinct subspec ...
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 North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
where native
horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million y ...
s and
camel A camel (from: la, camelus and grc-gre, κάμηλος (''kamēlos'') from Hebrew or Phoenician: גָמָל ''gāmāl''.) is an even-toed ungulate in the genus ''Camelus'' that bears distinctive fatty deposits known as "humps" on its back. C ...
s were wiped out. *
Asian land mammal ages The Asian land mammal ages, acronym ALMA, establish a geologic timescale for prehistoric Asian fauna beginning 58.7 Mya during the Paleogene and continuing through to the Miocene ( Aquitanian) (23.03 Ma). These periods are referred to as ages, sta ...
(ALMA) include Zhoukoudianian, Nihewanian, and Yushean. *
European land mammal ages The European Land Mammal Mega Zones (abbreviation: ELMMZ, more commonly known as European land mammal ages or ELMA) are zones in rock layers that have a specific assemblage of fossils (biozones) based on occurrences of fossil assemblages of Europe ...
(ELMA) include the
Villafranchian Villafranchian age ( ) is a period of geologic time (3.5–1.0 Ma) spanning the Late Pliocene and Early Pleistocene used more specifically with European Land Mammal Ages. Named by Italian geologist Lorenzo Pareto for a sequence of terrestrial s ...
, Galerian, and
Aurelian Aurelian ( la, Lucius Domitius Aurelianus; 9 September 214 October 275) was a Roman emperor, who reigned during the Crisis of the Third Century, from 270 to 275. As emperor, he won an unprecedented series of military victories which reunited t ...
*
North American land mammal ages The North American land mammal ages (NALMA) establishes a geologic timescale for North American fauna beginning during the Late Cretaceous and continuing through to the present. These periods are referred to as ages or intervals (or stages when ref ...
(NALMA) include
Blancan The Blancan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 4,750,000 to 1,806,000 years Before Present, BP, a period of .
(4.75–1.8),
Irvingtonian The Irvingtonian North American Land Mammal Age on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), spanning from 1.9 million – 250,000 years BP. ...
(1.8–0.24) and
Rancholabrean The Rancholabrean North American Land Mammal Age on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from less than 240,000 years to 11,000 years BP, a p ...
(0.24–0.01) in millions of years. The Blancan extends significantly back into the Pliocene. *
South American land mammal ages The South American land mammal ages (SALMA) establish a geologic timescale for prehistoric South American fauna beginning 64.5 Ma during the Paleocene and continuing through to the Late Pleistocene (0.011 Ma). These periods are referred to as age ...
(SALMA) include
Uquian The Uquian age is a period of geologic time (3.0–1.5 Ma) within the Pliocene and Pleistocene epochs of the Neogene used more specifically with South American Land Mammal Ages. It follows the Montehermosan and precedes the Ensenadan The Ensenad ...
(2.5–1.5),
Ensenadan The Ensenadan age is a period of geologic time (1.2–0.8 Ma) within the Early Pleistocene epoch of the Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the ...
(1.5–0.3) and
Lujanian The Lujanian age is a South American land mammal age within the Pleistocene and Holocene epochs of the Neogene, from 0.8–0.011 Ma or 800–11 tya. It follows the Ensenadan. The age is usually divided into the middle Pleistocene Bonaerian stag ...
(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
Russian Russian(s) refers to anything related to Russia, including: *Russians (, ''russkiye''), an ethnic group of the East Slavic peoples, primarily living in Russia and neighboring countries *Rossiyane (), Russian language term for all citizens and peo ...
scientists in collaboration with
Princeton University Princeton University is a private university, private research university in Princeton, New Jersey. Founded in 1746 in Elizabeth, New Jersey, Elizabeth as the College of New Jersey, Princeton is the List of Colonial Colleges, fourth-oldest ins ...
announced that they had brought two female
nematodes The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-parasitic nematodes also known as eelworms. They are a diverse animal phylum inhabiting a broa ...
frozen in
permafrost Permafrost is ground that continuously remains below 0 °C (32 °F) for two or more years, located on land or under the ocean. Most common in the Northern Hemisphere, around 15% of the Northern Hemisphere or 11% of the global surface ...
, 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 Spain is a country located in southwestern Europe occupying most (about 82 percent) of the Iberian Peninsula. It also includes a small exclave inside France called Llívia, as well as the Balearic Islands in the Mediterranean, the Canary Isla ...
, including
woolly mammoth The woolly mammoth (''Mammuthus primigenius'') is an extinct species of mammoth that lived during the Pleistocene until its extinction in the Holocene epoch. It was one of the last in a line of mammoth species, beginning with '' Mammuthus subp ...
, cave lions eating a
reindeer Reindeer (in North American English, known as caribou if wild and ''reindeer'' if domesticated) are deer in the genus ''Rangifer''. For the last few decades, reindeer were assigned to one species, ''Rangifer tarandus'', with about 10 subspe ...
,
horses The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...
, and
woolly rhinoceros The woolly rhinoceros (''Coelodonta antiquitatis'') is an extinct species of rhinoceros that was common throughout Europe and Asia during the Pleistocene epoch and survived until the end of the last glacial period. The woolly rhinoceros was a me ...
File:Pleistocene SA.jpg, Pleistocene of
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
, including ''
Megatherium ''Megatherium'' ( ; from Greek () 'great' + () 'beast') is an extinct genus of ground sloths endemic to South America that lived from the Early Pliocene through the end of the Pleistocene. It is best known for the elephant-sized type species ' ...
'' and two ''
Glyptodon ''Glyptodon'' (from Greek for 'grooved or carved tooth': γλυπτός 'sculptured' and ὀδοντ-, ὀδούς 'tooth') is a genus of glyptodont (an extinct group of large, herbivorous armadillos) that lived from the Pleistocene, around 2.5 ...
''


Humans

The
evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
of
anatomically modern humans Early modern human (EMH) or anatomically modern human (AMH) are terms used to distinguish ''Homo sapiens'' (the only extant Hominina species) that are anatomically consistent with the range of phenotypes seen in contemporary humans from extin ...
took place during the Pleistocene. In the beginning of the Pleistocene ''
Paranthropus ''Paranthropus'' is a genus of extinct hominin which contains two widely accepted species: ''Paranthropus robustus, P. robustus'' and ''P. boisei''. However, the validity of ''Paranthropus'' is contested, and it is sometimes considered to be sy ...
'' species were still present, as well as early human ancestors, but during the lower Palaeolithic they disappeared, and the only
hominin The Hominini form a taxonomic tribe of the subfamily Homininae ("hominines"). Hominini includes the extant genera ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos) and in standard usage excludes the genus ''Gorilla'' (gorillas). The t ...
species found in fossilic records is ''
Homo erectus ''Homo erectus'' (; meaning "upright man") is an extinct species of archaic human from the Pleistocene, with its earliest occurrence about 2 million years ago. Several human species, such as '' H. heidelbergensis'' and '' H. antecessor' ...
'' for much of the Pleistocene.
Acheulean Acheulean (; also Acheulian and Mode II), from the French ''acheuléen'' after the type site of Saint-Acheul, is an archaeological industry of stone tool manufacture characterized by the distinctive oval and pear-shaped "hand axes" associated ...
lithics Lithic may refer to: *Relating to stone tools **Lithic analysis, the analysis of stone tools and other chipped stone artifacts **Lithic core, the part of a stone which has had flakes removed from it **Lithic flake, the portion of a rock removed to ...
appear along with ''Homo erectus'', some 1.8 million years ago, replacing the more primitive
Oldowan The Oldowan (or Mode I) was a widespread stone tool archaeological industry (style) in prehistory. These early tools were simple, usually made with one or a few flakes chipped off with another stone. Oldowan tools were used during the Lower ...
industry used by ''
A. garhi ''Australopithecus garhi'' is a species of australopithecine from the Bouri Formation in the Afar Region of Ethiopia 2.6–2.5 million years ago (mya) during the Early Pleistocene. The first remains were described in 1999 based on several skele ...
'' and by the earliest species of ''Homo''. The
Middle Paleolithic The Middle Paleolithic (or Middle Palaeolithic) is the second subdivision of the Paleolithic or Old Stone Age as it is understood in Europe, Africa and Asia. The term Middle Stone Age is used as an equivalent or a synonym for the Middle Paleoli ...
saw more varied speciation within ''Homo'', including the appearance of ''
Homo sapiens Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
'' about 300,000 years ago. According to mitochondrial timing techniques,
modern humans Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, an ...
migrated from Africa after the
Riss glaciation The Riss glaciation, Riss Glaciation, Riss ice age, Riss Ice Age, Riss glacial or Riss Glacial (german: Riß-Kaltzeit, ', ' or (obsolete) ') is the second youngest glaciation of the Pleistocene epoch in the traditional, quadripartite glacial classi ...
in the Middle Palaeolithic during the
Eemian Stage The Eemian (also called the last interglacial, Sangamonian Stage, Ipswichian, Mikulin, Kaydaky, penultimate,NOAA - Penultimate Interglacial Period http://www.ncdc.noaa.gov/global-warming/penultimate-interglacial-period Valdivia or Riss-Würm) wa ...
, spreading all over the ice-free world during the late Pleistocene. A 2005 study posits that humans in this migration interbred with
archaic human A number of varieties of ''Homo'' are grouped into the broad category of archaic humans in the period that precedes and is contemporary to the emergence of the earliest early modern humans (''Homo sapiens'') around 300 ka. Omo-Kibish I (Omo I) f ...
forms already outside of Africa by the late Pleistocene, incorporating archaic human genetic material into the modern human gene pool.


See also

*
Climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
* Pleistocene megafauna * Pleistocene Park * Timeline of glaciation


Explanatory notes


References

* Ogg, Jim (June 2004)
"Overview of Global Boundary Stratotype Sections and Points (GSSP's)"
International Commission on Stratigraphy. Retrieved 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, 1830s neologisms Articles which contain graphical timelines Geological epochs Quaternary geochronology