The Holocene ( /ˈhɒləˌsiːn, ˈhoʊ-/) 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.
The Holocene has seen the growth and impacts of the human species worldwide, including all its written history, development of major civilizations, and overall significant transition toward 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.
|Subdivisions of the Quaternary System|
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 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.
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.
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.
Post-glacial rebound in the Scandinavia region resulted in the formation of the Baltic Sea. 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.
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.
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.
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 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 Anthropocene is a proposed epoch dating from the commencement of significant human impact on the Earth's geology and ecosystems, including, but not limited to, anthropogenic climate change.As of August 2016, neither the International Commission on Stratigraphy nor the International Union of Geological Sciences (IUGS) has yet officially approved the term as a recognized subdivision of geological time, although the Anthropocene Working Group (AWG) of the Subcommission on Quaternary Stratigraphy (SQS) of the International Commission on Stratigraphy (ICS), voted to proceed towards a formal golden spike (GSSP) proposal to define the Anthropocene epoch in the Geologic Time Scale and presented the recommendation to the International Geological Congress on 29 August 2016.Various start dates for the Anthropocene have been proposed, ranging from the beginning of the Agricultural Revolution 12,000–15,000 years ago, to as recent as the Trinity test in 1945. As of February 2018, the ratification process continues and thus a date remains to be decided definitively, but the latter date has been more favoured than others.
The most recent period of the Anthropocene has been referred to by several authors as the Great Acceleration during which the socioeconomic and earth system trends are increasing dramatically, especially after the Second World War. For instance, the Geological Society termed the year 1945 as The Great Acceleration.Apodiformes
Traditionally, the bird order Apodiformes contained three living families: the swifts (Apodidae), the treeswifts (Hemiprocnidae), and the hummingbirds (Trochilidae). In the Sibley-Ahlquist taxonomy, this order is raised to a superorder Apodimorphae in which hummingbirds are separated as a new order, Trochiliformes. With nearly 450 species identified to date, they are the most diverse order of birds after the passerines.Bond event
Bond events are North Atlantic ice rafting events that are tentatively linked to climate fluctuations in the Holocene. Eight such events have been identified. Bond events were previously believed to exhibit a quasi c. 1,500-year cycle, but the primary period of variability is now put at c. 1,000 years.Gerard C. Bond of the Lamont–Doherty Earth Observatory at Columbia University was the lead author of the 1997 paper that postulated the theory of 1470-year climate cycles in the Late Pleistocene and Holocene, mainly based on petrologic tracers of drift ice in the North Atlantic. However, more recent work has shown that these tracers provide little support for 1,500-year intervals of climate change, and the reported c. 1,500 ± 500-year period was a statistical artifact. Furthermore, following publication of the Greenland Ice Core Chronology 2005 (GICC05) for the North GRIP ice core, it became clear that Dansgaard–Oeschger events also show no such pattern. The North Atlantic ice-rafting events happen to correlate with episodes of lowered lake levels in the Mid-Atlantic region, USA, the weakest events of the Asian monsoon for at least the past 9,000 years, and also correlate with most aridification events in the Middle East for the past 55,000 years (both Heinrich and Bond events).For reasons that are unclear, the only Holocene Bond event that has a clear temperature signal in the Greenland ice cores is the 8.2 kiloyear event.Cascade point
A Cascade point is a projectile point associated with the Cascade phase, an ancient culture of Native Americans that settled in the Pacific Northwest that existed from 9000 or 10000 BC until about 5500 BC.
The Cascade (Bipointed) point is typically narrow, lanceolate leaf shaped, with either a pointed or rounded base. There are also two other variants, one with a shallow concave base and the other with a sharply contracting basal margin..Cascade points are generally regarded as poor temporal markers because they are found in early, middle, and even late Holocene contexts. It is unclear whether this broad timespan is a function of prolonged use of the point form, later groups recycling discarded artifacts, or a combination of both. The spatial and temporal distribution of foliate points in the northern Great Basin and present new data derived from work at a stratified rockshelter in Oregon's Warner Valley have been reviewed. There, we have uncovered foliate projectile points that meet the original definition and more recent refinements of the Cascade point type associated with a late early Holocene and middle Holocene occupation. We present technological and source provenance data for the points and the associated lithic assemblage and reconstruct how prehistoric foragers used the rockshelter.A projectile found lodged in the hip of Kennewick Man was leaf-shaped, long, broad and had serrated edges.Epoch (geology)
In geochronology, an epoch is a subdivision of the geologic timescale that is longer than an age but shorter than a period. The current epoch is the Holocene Epoch of the Quaternary Period. Rock layers deposited during an epoch are called a series. Series are subdivisions of the stratigraphic column that, like epochs, are subdivisions of the geologic timescale. Like other geochronological divisions, epochs are normally separated by significant changes in the rock layers to which they correspond.
Epochs are most commonly used for the younger Cenozoic Era, where a greater collection of fossils has been found and paleontologists have more detailed knowledge of the events that occurred during those times. They are less commonly referred to for the other eras and eons, since less fossil evidence exists that allows us to form a clearer view of those time periods.Haleakalā
Haleakalā (; Hawaiian: [ˈhɐlɛˈjɐkəˈlaː]), or the East Maui Volcano, is a massive shield volcano that forms more than 75% of the Hawaiian Island of Maui. The western 25% of the island is formed by another volcano, Mauna Kahalawai, also referred to as the West Maui Mountains.
The tallest peak of Haleakalā ("house of the sun"), at 10,023 feet (3,055 m), is Puʻu ʻUlaʻula (Red Hill). From the summit one looks down into a massive depression some 11.25 km (7 mi) across, 3.2 km (2 mi) wide, and nearly 800 m (2,600 ft) deep. The surrounding walls are steep and the interior mostly barren-looking with a scattering of volcanic cones.Holocene calendar
The Holocene calendar, also known as the Holocene Era or Human Era (HE), is a year numbering system that adds exactly 10,000 years to the currently dominant (AD/BC or CE/BCE) numbering scheme, placing its first year near the beginning of the Holocene geological epoch and the Neolithic Revolution, when humans transitioned from a hunter-gatherer lifestyle to agriculture and fixed settlements. The year 2019 in the Holocene calendar is 12019 HE. The HE scheme was first proposed by Cesare Emiliani in 1993 (11993 HE).Holocene climatic optimum
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.
This warm period was followed by a gradual decline until about two millennia ago.
For other temperature fluctuations, see temperature record.
For other past climate fluctuation, see paleoclimatology.
For the pollen zone and Blytt-Sernander period, associated with the climate optimum, see Atlantic (period).Holocene extinction
The Holocene extinction, otherwise referred to as the Sixth extinction or Anthropocene extinction, is a current event, and is one of the most significant extinction events in the history of the Earth. This ongoing extinction of species coincides with the present Holocene epoch (approx. 11,700 years), and is a result of human activity. This large number of extinctions spans numerous families of plants and animals, including mammals, birds, amphibians, reptiles and arthropods. With widespread degradation of highly biodiverse habitats such as coral reefs and rainforests, as well as other areas, the vast majority of these extinctions are thought to be undocumented, as no one is even aware of the existence of the species before they go extinct, or no one has yet discovered their extinction. The current rate of extinction of species is estimated at 100 to 1,000 times higher than natural background rates.The Holocene extinction includes the disappearance of large land animals known as megafauna, starting at the end of the last Ice Age. Megafauna outside of the African continent, which did not evolve alongside humans, proved highly sensitive to the introduction of new predation, and many died out shortly after early humans began spreading and hunting across the Earth (additionally, many African species have also gone extinct in the Holocene). These extinctions, occurring near the Pleistocene–Holocene boundary, are sometimes referred to as the Quaternary extinction event.
The most popular theory is that human overhunting of species added to existing stress conditions as the extinction coincides with human emergence. Although there is debate regarding how much human predation affected their decline, certain population declines have been directly correlated with human activity, such as the extinction events of New Zealand and Hawaii. Aside from humans, climate change may have been a driving factor in the megafaunal extinctions, especially at the end of the Pleistocene.
Ecologically, humanity has been noted as an unprecedented "global superpredator" that consistently preys on the adults of other apex predators, and has worldwide effects on food webs. There have been extinctions of species on every land mass and in every ocean: there are many famous examples within Africa, Asia, Europe, Australia, North and South America, and on smaller islands. Overall, the Holocene extinction can be linked to the human impact on the environment. The Holocene extinction continues into the 21st century, with meat consumption, overfishing, ocean acidification and the decline in amphibian populations being a few broader examples of an almost universal, cosmopolitan decline in biodiversity. Human overpopulation (and continued population growth) along with profligate consumption are considered to be the primary drivers of this rapid decline.Last Glacial Period
The Last Glacial Period (LGP) occurred from the end of the Eemian interglacial 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 (Eocene–Oligocene extinction event). The term Late Cenozoic Ice Age is used to include this early phase.During this last glacial period there were alternating episodes of glacier advance and retreat. Within the last glacial period the Last Glacial Maximum was approximately 22,000 years ago. While the general pattern of global cooling and glacier advance was similar, local differences in the development of glacier advance and retreat make it difficult to compare the details from continent to continent (see picture of ice core data below for differences). Approximately 13,000 years ago, the Late Glacial Maximum began. The end of the Younger Dryas about 11,700 years ago marked the beginning of the Holocene geological epoch, which includes the Holocene glacial retreat.
From the point of view of human archaeology, the last glacial period falls in the Paleolithic and early Mesolithic periods. When the glaciation event started, Homo sapiens were confined to lower latitudes and used tools comparable to those used by Neanderthals in western and central Eurasia and by Homo erectus in Asia. Near the end of the event, Homo sapiens migrated into Eurasia and Australia. Archaeological and genetic data suggest that the source populations of Paleolithic humans survived the last glacial period in sparsely wooded areas and dispersed through areas of high primary productivity while avoiding dense forest cover.Late Pleistocene
The Late Pleistocene is a geochronological age of the Pleistocene Epoch and is associated with Upper Pleistocene (or Tarantian) stage rocks. The beginning of the stage is defined by the base of the Eemian interglacial phase before the final glacial episode of the Pleistocene 126,000 ± 5,000 years ago. Its end is defined at the end of the Younger Dryas, some 11,700 years ago. The age represents the end of the Pleistocene epoch and is followed by the Holocene epoch.
Much of the Late Pleistocene age was dominated by glaciations, such as the Wisconsin glaciation in North America and the Weichselian glaciation and Würm glaciation in Eurasia). Many megafauna became extinct during this age, a trend that continued into the Holocene. The Late Pleistocene contains the Upper Paleolithic stage of human development, including the out-of-Africa migration and dispersal of anatomically modern humans and the extinction of the last remaining archaic human species.List of volcanoes in Canada
A list of volcanoes in Canada.List of volcanoes in Russia
This is a list of active and extinct volcanoes in Russia.Mammoth
A mammoth is any species of the extinct 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, in northern species, a covering of long hair. They lived from the Pliocene epoch (from around 5 million years ago) into the Holocene at about 4,000 years ago, and various species existed in Africa, Europe, Asia, and North America. They were members of the family Elephantidae, which also contains the two genera of modern elephants and their ancestors.
The oldest representative of Mammuthus, the South African mammoth (M. subplanifrons), appeared around 5 million years ago during the early Pliocene in what is now southern and eastern Africa. Descendant species of these mammoths moved north and continued to propagate into numerous subsequent species, eventually covering most of Eurasia before extending into the Americas at least 600,000 years ago. The last species to emerge, the woolly mammoth (M. primigenius), developed about 400,000 years ago in East Asia, with some surviving on Russia's Wrangel Island in the Arctic Ocean until as recently as roughly 3,700 to 4,000 years ago, still extant during the construction of the Great Pyramid of ancient Egypt.Mount Damavand
Mount Damavand (Persian: دماوند [dæmɒːvænd] (listen)), a potentially active volcano, is a stratovolcano which is the highest peak in Iran and the highest volcano in Asia; the Kunlun Volcanic Group in Tibet is higher than Damāvand, but are not considered to be volcanic mountains.
Damāvand has a special place in Persian mythology and folklore. It is in the middle of the Alborz range, adjacent to Varārū, Sesang, Gol-e Zard, and Mīānrūd. It is near the southern coast of the Caspian Sea, in Amol County, Mazandaran Province, 66 kilometres (41 miles) northeast of the city of Tehran.Mount Damāvand is the 12th most prominent peak in the world, and the second most prominent in Asia after Mount Everest. It is the highest volcanic mountain in Asia, and part of the Volcanic Seven Summits mountaineering challenge.Neontology
Neontology is a part of biology that, in contrast to paleontology, deals with living (or, more generally, recent) organisms. It is the study of extant taxa (singular: extant taxon): taxa (such as species, genera and families) with members still alive, as opposed to (all) being extinct. For example:
The moose (Alces alces) is an extant species, and the dodo is an extinct species.
In the group of molluscs known as the cephalopods, as of 1987 there were approximately 600 extant species and 7,500 extinct species.A taxon can be classified as extinct if it is broadly agreed or certified that no members of the group are still alive. Conversely, an extinct taxon can be reclassified as extant if there are new discoveries of extant species ("Lazarus species"), or if previously-known extant species are reclassified as members of the taxon.
Most biologists, zoologists, and botanists are in practice neontologists, and the term neontologist is used largely by paleontologists referring to non-paleontologists. Stephen Jay Gould said of neontology:
All professions maintain their parochialisms, and I trust that nonpaleontological readers will forgive our major manifestation. We are paleontologists, so we need a name to contrast ourselves with all you folks who study modern organisms in human or ecological time. You therefore become neontologists. We do recognize the unbalanced and parochial nature of this dichotomous division.
Neontological evolutionary biology has a temporal perspective between 100 to 1000 years. Neontology's fundamental basis relies on models of natural selection as well as speciation. Neontology's methods, when compared to evolutionary paleontology, has a greater emphasis on experiments. There are more frequent discontinuities present in paleontology than in neontology, because paleontology involves extinct taxa. Neontology has organisms actually present and available to sample and perform research on. Neontology's research method uses cladistics to examine morphologies and genetics. Neontology data has more emphasis on genetic data and the population structure than paleontology does.Quaternary
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 (2.588 million years ago to 11.7 thousand years ago) and the Holocene (11.7 thousand years ago to today). The informal term "Late Quaternary" refers to the past 0.5–1.0 million years.The Quaternary Period is typically defined by the cyclic growth and decay of continental ice sheets associated with Milankovitch cycles and the associated climate and environmental changes that occurred.Twin Cone
Twin Cone is a cinder cone in northern British Columbia, Canada. It is thought to have last erupted in the Holocene period.Zaniolepis
Zaniolepis is a genus of scorpaeniform fish native to the eastern Pacific Ocean. Z. frenata is known to have been a source of food to the Native American inhabitants of San Nicolas Island off the coast of southern California, United States during the Middle Holocene.