| Holocene Epoch|
0.0117–0 million years ago
|Subdivisions of the Quaternary System|
|Part of a series on|
| Human History |
|↑ Prehistory ( Pleistocene epoch )|
|Preceded by the Pleistocene|
| Holocene |
Holocene temperature variations
*Relative to year 2000 (b2k).†Relative to year 1950 (BP/Before "Present").
The Holocene ( /, -, -, -/ HOL-ə-seen, HOL-oh-, HOH-lə-, HOH-loh-) 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 together form the Quaternary period. The Holocene has been identified with the current warm period, known as MIS 1. It is considered by some to be an interglacial period within the Pleistocene Epoch, called the Flandrian interglacial.
The Holocene corresponds with rapid proliferation, growth and impacts of the human species worldwide, including all of its written history, technological revolutions, development of major civilizations, and overall significant transition towards urban living in the present. Human impacts on modern-era Earth and its ecosystems may be considered of global significance for future evolution of living species, including approximately synchronous lithospheric evidence, or more recently hydrospheric and atmospheric evidence of human impacts. In July 2018, the International Union of Geological Sciences split the Holocene epoch into three distinct subsections, Greenlandian (11,700 years ago to 8,326 years ago), Northgrippian (8,326 years ago to 4,200 years ago) and Meghalayan (4,200 years ago to the present), as proposed by International Commission on Stratigraphy.The boundary stratotype of Meghalayan is a speleothem in Mawmluh cave in India, and the global auxiliary stratotype is an ice core from Mount Logan in Canada.
The word is formed from two Ancient Greek words. Holos (ὅλος) is the Greek word for "whole." "Cene" comes from the Greek word kainos (καινός), meaning "new." The concept is that this epoch is "entirely new." The suffix '-cene' is used for all the seven epochs of the Cenozoic Era.
It is accepted by the International Commission on Stratigraphy that the Holocene started approximately 11,650 cal years BP.The Subcommission on Quaternary Stratigraphy quotes Gibbard and van Kolfschoten in Gradstein Ogg and Smith in stating the term 'Recent' as an alternative to Holocene is invalid and should not be used and also observe that the term Flandrian, derived from marine transgression sediments on the Flanders coast of Belgium has been used as a synonym for Holocene by authors who consider the last 10,000 years should have the same stage-status as previous interglacial events and thus be included in the Pleistocene. The International Commission on Stratigraphy, however, considers the Holocene an epoch following the Pleistocene and specifically the last glacial period. Local names for the last glacial period include the Wisconsinan in North America, the Weichselian in Europe, the Devensian in Britain, the Llanquihue in Chile and the Otiran in New Zealand.
The Holocene can be subdivided into five time intervals, or chronozones, based on climatic fluctuations:
The Blytt–Sernander classification of climatic periods initially defined by plant remains in peat mosses, is currently being explored. Geologists working in different regions are studying sea levels, peat bogs and ice core samples by a variety of methods, with a view toward further verifying and refining the Blytt–Sernander sequence. They find a general correspondence across Eurasia and North America, though the method was once thought to be of no interest. The scheme was defined for Northern Europe, but the climate changes were claimed to occur more widely. The periods of the scheme include a few of the final pre-Holocene oscillations of the last glacial period and then classify climates of more recent prehistory.[ citation needed ]
Paleontologists have not defined any faunal stages for the Holocene. If subdivision is necessary, periods of human technological development, such as the Mesolithic, Neolithic, and Bronze Age, are usually used. However, the time periods referenced by these terms vary with the emergence of those technologies in different parts of the world.[ citation needed ]
Climatically, the Holocene may be divided evenly into the Hypsithermal and Neoglacial periods; the boundary coincides with the start of the Bronze Age in Europe. According to some scholars, a third division, the Anthropocene, has now begun.The International Commission on Stratigraphy Subcommission on Quaternary Stratigraphy's working group on the 'Anthropocene' (a term coined by Paul Crutzen and Eugene Stoermer in 2000) note this term is used to denote the present time interval in which many geologically significant conditions and processes have been profoundly altered by human activities. The 'Anthropocene' is not a formally defined geological unit.
Continental motions due to plate tectonics are less than a kilometre over a span of only 10,000 years. However, ice melt caused world sea levels to rise about 35 m (115 ft) in the early part of the Holocene. In addition, many areas above about 40 degrees north latitude had been depressed by the weight of the Pleistocene glaciers and rose as much as 180 m (590 ft) due to post-glacial rebound over the late Pleistocene and Holocene, and are still rising today.
The sea level rise and temporary land depression allowed temporary marine incursions into areas that are now far from the sea. Holocene marine fossils are known, for example, from Vermont and Michigan. Other than higher-latitude temporary marine incursions associated with glacial depression, Holocene fossils are found primarily in lakebed, floodplain, and cave deposits. Holocene marine deposits along low-latitude coastlines are rare because the rise in sea levels during the period exceeds any likely tectonic uplift of non-glacial origin.[ citation needed ]
Post-glacial rebound in the Scandinavia region resulted in the formation of the Baltic Sea. Earthquakes are a leading cause of sediment deformation, leading to the creation and destruction of bodies of water.The region continues to rise, still causing weak earthquakes across Northern Europe. The equivalent event in North America was the rebound of Hudson Bay, as it shrank from its larger, immediate post-glacial Tyrrell Sea phase, to near its present boundaries.
Climate has been fairly stable over the Holocene. Ice core records show that before the Holocene there was global warming after the end of the last ice age and cooling periods, but climate changes became more regional at the start of the Younger Dryas. During the transition from the last glacial to the Holocene, the Huelmo–Mascardi Cold Reversal in the Southern Hemisphere began before the Younger Dryas, and the maximum warmth flowed south to north from 11,000 to 7,000 years ago. It appears that this was influenced by the residual glacial ice remaining in the Northern Hemisphere until the later date.[ citation needed ]
The Holocene climatic optimum (HCO) was a period of warming in which the global climate became warmer. However, the warming was probably not uniform across the world. This period of warmth ended about 5,500 years ago with the descent into the Neoglacial and concomitant Neopluvial. At that time, the climate was not unlike today's, but there was a slightly warmer period from the 10th–14th centuries known as the Medieval Warm Period. This was followed by the Little Ice Age, from the 13th or 14th century to the mid-19th century.
Compared to glacial conditions, habitable zones have expanded northwards, reaching their northernmost point during the HCO. Greater moisture in the polar regions has caused the disappearance of steppe-tundra.[ citation needed ]
The temporal and spatial extent of Holocene climate change is an area of considerable uncertainty, with radiative forcing recently proposed to be the origin of cycles identified in the North Atlantic region. Climate cyclicity through the Holocene (Bond events) has been observed in or near marine settings and is strongly controlled by glacial input to the North Atlantic.Periodicities of ≈2500, ≈1500, and ≈1000 years are generally observed in the North Atlantic. At the same time spectral analyses of the continental record, which is remote from oceanic influence, reveal persistent periodicities of 1,000 and 500 years that may correspond to solar activity variations during the Holocene epoch. A 1,500-year cycle corresponding to the North Atlantic oceanic circulation may have had widespread global distribution in the Late Holocene.
Animal and plant life have not evolved much during the relatively short Holocene, but there have been major shifts in the distributions of plants and animals. A number of large animals including mammoths and mastodons, saber-toothed cats like Smilodon and Homotherium , and giant sloths disappeared in the late Pleistocene and early Holocene—especially in North America, where animals that survived elsewhere (including horses and camels) became extinct. This extinction of American megafauna has been explained as caused by the arrival of the ancestors of Amerindians; though most scientists assert that climatic change also contributed. In addition, a controversial bolide impact over North America has been hypothesized to have triggered the Younger Dryas.
Throughout the world, ecosystems in cooler climates that were previously regional have been isolated in higher altitude ecological "islands".
The 8.2 ka event , an abrupt cold spell recorded as a negative excursion in the δ18O record lasting 400 years, is the most prominent climatic event occurring in the Holocene epoch, and may have marked a resurgence of ice cover. It has been suggested that this event was caused by the final drainage of Lake Agassiz, which had been confined by the glaciers, disrupting the thermohaline circulation of the Atlantic. Subsequent research, however, suggested that the discharge was probably superimposed upon a longer episode of cooler climate lasting up to 600 years and observed that the extent of the area affected was unclear.
This section contains close paraphrasing of a non-free copyrighted source, http://boletinsgm.igeolcu.unam.mx/bsgm/vols/epoca04/7001/%284%29Franco.pdf ( ). (May 2018) (Learn how and when to remove this template message)
The beginning of the Holocene corresponds with the beginning of the Mesolithic age in most of Europe, but in regions such as the Middle East and Anatolia with a very early neolithisation, Epipaleolithic is preferred in place of Mesolithic. Cultures in this period include Hamburgian, Federmesser, and the Natufian culture, during which the oldest inhabited places still existing on Earth were first settled, such as Tell es-Sultan (Jericho) in the Middle East.There is also evolving archeological evidence of proto-religion at locations such as Göbekli Tepe, as long ago as the 9th millennium BCE.
Both are followed by the aceramic Neolithic (Pre-Pottery Neolithic A and Pre-Pottery Neolithic B) and the pottery Neolithic. The Late Holocene brought advancements such as the bow and arrow and saw new methods of warfare in North America. Spear throwers and their large points were replaced by the bow and arrow with its small narrow points beginning in Oregon and Washington. Villages built on defensive bluffs indicate increased warfare, leading to food gathering in communal groups for protection rather than individual hunting.In Mesoamerica, transformations of natural environments have been a common feature at least since the mid-Holocene, mostly through the exploitation of wild plants and the establishment of crops.
The Pleistocene is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the world's most recent period of repeated glaciations. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the Paleolithic age used in archaeology.
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 2.588 ± 0.005 million years ago to the present. The Quaternary Period is divided into two epochs: the Pleistocene and the Holocene. The informal term "Late Quaternary" refers to the past 0.5–1.0 million years.
The Younger Dryas was a return to glacial conditions after the Late Glacial Interstadial, which temporarily reversed the gradual climatic warming after the Last Glacial Maximum (LGM) started receding around 20,000 BP. It is named after an indicator genus, the alpine-tundra wildflower Dryas octopetala, as its leaves are occasionally abundant in late glacial, often minerogenic-rich sediments, such as the lake sediments of Scandinavia.
The Last Glacial Period (LGP) occurred from the end of the Eemian to the end of the Younger Dryas, encompassing the period c. 115,000 – c. 11,700 years ago. This most recent glacial period is part of a larger pattern of glacial and interglacial periods known as the Quaternary glaciation extending from c. 2,588,000 years ago to present. The definition of the Quaternary as beginning 2.58 Ma is based on the formation of the Arctic ice cap. The Antarctic ice sheet began to form earlier, at about 34 Ma, in the mid-Cenozoic. The term Late Cenozoic Ice Age is used to include this early phase.
There have been five or six major ice ages in the history of Earth over the past 3 billion years. The Late Cenozoic Ice Age began 34 million years ago, its latest phase being the Quaternary glaciation, in progress since 2.58 million years ago.
A glacial period is an interval of time within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate between glacial periods. The last glacial period ended about 15,000 years ago. The Holocene epoch is the current interglacial. A time with no glaciers on Earth is considered a greenhouse climate state.
The Anglian Stage is the name used in the British Isles for a middle Pleistocene glaciation. It precedes the Hoxnian Stage and follows the Cromerian Stage in the British Isles. The Anglian Stage is correlated to Marine Isotope Stage 12, which started about 478,000 years ago and ended about 424,000 years ago.
The Hoxnian Stage is a middle Pleistocene stage of the geological history of the British Isles. It precedes the Wolstonian Stage and follows the Anglian Stage. It is equivalent to Marine Isotope Stage 11. Marine Isotope Stage 11 started 424,000 years ago and ended 374,000 years ago. The Hoxnian divided into sub-stages Ho I to Ho IV.
The Holocene Climate Optimum (HCO) was a warm period during roughly the interval 9,000 to 5,000 years BP, with a thermal maximum around 8000 years BP. It has also been known by many other names, such as Altithermal, Climatic Optimum, Holocene Megathermal, Holocene Optimum, Holocene Thermal Maximum, Hypsithermal, and Mid-Holocene Warm Period.
The Illinoian Stage is the name used by Quaternary geologists in North America to designate the period c.191,000 to c.130,000 years ago, during the middle Pleistocene, when sediments comprising the Illinoian Glacial Lobe were deposited. It precedes the Sangamonian Stage and follows the Pre-Illinoian Stage in North America. The Illinoian Stage is defined as the period of geologic time during which the glacial tills and outwash, which comprise the bulk of the Glasford Formation, accumulated to create the Illinoian Glacial Lobe. It occurs at about the same time as the penultimate glacial period.
During the Last Glacial Maximum, the mammoth steppe was the Earth’s most extensive biome. It spanned from Spain eastwards across Eurasia to Canada and from the arctic islands southwards to China. It had a cold, dry climate; the vegetation was dominated by palatable high-productivity grasses, herbs and willow shrubs, and the animal biomass was dominated by bison and horses. This ecosystem covered wide areas of the northern part of the globe, thrived for approximately 100,000 years without major changes, and then suddenly became all but extinct about 12,000 years ago.
The Chibanian is an age in the international geologic timescale or a stage in chronostratigraphy, being the second division of the Pleistocene Epoch within the ongoing Quaternary Period. Before the Chibanian name was officially ratified in January 2020, the time interval and its rocks were known as the Middle Pleistocene. It is currently estimated to span the time between 0.770 Ma and 0.126 Ma, also expressed as 770–126 ka. It includes the transition in palaeoanthropology from the Lower to the Middle Palaeolithic over 300 ka.
The Late Pleistocene is an unofficial sub-epoch in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a stratigraphic perspective. It is intended to be the third division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently estimated to span the time between c. 129,000 and c. 11,700 years ago. The Late Pleistocene equates to the proposed Tarantian Age of the geologic time scale, preceded by the officially ratified Chibanian and succeeded by the officially ratified Greenlandian. The estimated beginning of the Tarantian is the start of the Eemian interglacial period. It is held to end with the termination of the Younger Dryas, some 11,700 years ago when the Holocene Epoch began.
The Oldest Dryas is a biostratigraphic subdivision layer corresponding to an abrupt cooling event, or stadial, which occurred during the last glacial retreat. The time period to which the layer corresponds varies between regions, but it is generally dated as starting at 18.5-17 ka BP and ending 15-14 ka BP. As with the Younger and Older Dryas events, the stratigraphic layer is marked by abundance of the pollen and other remains of Dryas octopetala, an indicator species that colonizes arctic-alpine regions. In the Alps, the Oldest Dryas corresponds to the Gschnitz stadial of the Würm glaciation. The term was originally defined specifically for terrestrial records in the region of Scandinavia, but has come to be used both for ice core stratigraphy in areas across the world and to refer to the time period itself and its associated temporary reversal of the glacial retreat.
The Quaternary glaciation, also known as the Pleistocene glaciation, is an alternating series of glacial and interglacial periods during the Quaternary period that began 2.58 Ma, and is ongoing. Although geologists describe the entire time period as an "ice age", in popular culture the term "ice age" is usually associated with just the most recent glacial period during the Pleistocene. Since the planet Earth still has ice sheets, geologists consider the Quaternary glaciation to be ongoing, with the Earth now experiencing an interglacial period.
The 4.2-kiloyear BP aridification event was one of the most severe climatic events of the Holocene epoch. It defines the beginning of the current Meghalayan age in the Holocene epoch. Starting in about 2200 BC, it probably lasted the entire 22nd century BC. It has been hypothesised to have caused the collapse of the Old Kingdom in Egypt as well as the Akkadian Empire in Mesopotamia, and the Liangzhu culture in the lower Yangtze River area. The drought may also have initiated the collapse of the Indus Valley Civilisation, with some of its population moving southeastward to follow the movement of their desired habitat, as well as the migration of Indo-European-speaking people into India.
In climatology, the 8.2-kiloyear event was a sudden decrease in global temperatures that occurred approximately 8,200 years before the present, or c. 6,200 BC, and which lasted for the next two to four centuries. It defines the start of the Northgrippian age in the Holocene epoch. Milder than the Younger Dryas cold spell before it but more severe than the Little Ice Age after it, the 8.2-kiloyear cooling was a significant exception to general trends of the Holocene climatic optimum. During the event, atmospheric methane concentration decreased by 80 ppb, an emission reduction of 15%, by cooling and drying at a hemispheric scale.
The Subboreal is a climatic period, immediately before the present one, of the Holocene. It lasted from 3710 to 450 BCE.
The Carbajal Valley is a valley in the Fuegian Andes of southern Tierra del Fuego Province, Argentina. The Carbajal valley is approximately 20 kilometres (12 mi) long, running west to east, between the Alvear mountain range to the north and the Vinciguerra range to the south. Andes peak heights in the region are generally less than 1,250 metres (4,100 ft) above sea level.
The early Holocene sea level rise (EHSLR) was a significant jump in sea level by about 60 m during the early Holocene, between about 12,000 and 7,000 years ago, spanning the Eurasian Mesolithic. The rapid rise in sea level and associated climate change, notably the 8.2 ka cooling event , and the loss of coastal land favoured by early farmers, may have contributed to the spread of the Neolithic to Europe.
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