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The Holocene is the current geological epoch, beginning approximately 11,700 years ago. It follows 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 Pleistocene is the geological epoch that lasted from c. 2.58 million to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in 2009 by the International Union of Geological Sciences, the cutoff of the Pleistocene and the preceding Pliocene was regarded as being 1.806 million years Before Present (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 age used in archaeology. The name is a combination of Ancient Greek πλεῖστος (pleîstos), meaning "most", and καινός, meaning "new".
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 ago to the present. As of 2023, the Quaternary Period is divided into two epochs: the Pleistocene and the Holocene ; a third epoch, the Anthropocene, has recently been proposed, but it is not officially recognised by the ICS.
The 8th millennium BC spanned the years 8000 BC to 7001 BC. In chronological terms, it is the second full millennium of the current Holocene epoch and is entirely within the Pre-Pottery Neolithic B (PPNB) phase of the Early Neolithic. It is impossible to precisely date events that happened around the time of this millennium and all dates mentioned here are estimates mostly based on geological and anthropological analysis, or by radiometric dating.
The 10th millennium BC spanned the years 10,000 BC to 9001 BC. It marks the beginning of the transition from the Palaeolithic to the Neolithic via the interim Mesolithic and Epipaleolithic periods, which together form the first part of the Holocene epoch that is generally believed to have begun c. 9700 BC and is the current geological epoch. It is impossible to precisely date events that happened around the time of this millennium, and all dates mentioned here are estimates mostly based on geological analysis, anthropological analysis, and radiometric dating.
The International Commission on Stratigraphy (ICS), sometimes unofficially referred to as the "International Stratigraphic Commission", is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigraphical, geological, and geochronological matters on a global scale.
Before Present (BP) years, also known as "time before present" or "years before present (YBP)", 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. Because the "present" time changes, standard practice is to use 1 January 1950 as the commencement date (epoch) of the age scale. The abbreviation "BP" has been interpreted retrospectively as "Before Physics", which refers to the time before nuclear weapons testing artificially altered the proportion of the carbon isotopes in the atmosphere, which scientists must now account for.
The Gelasian is an age in the international geologic timescale or a stage in chronostratigraphy, being the earliest or lowest subdivision of the Quaternary Period/System and Pleistocene Epoch/Series. It spans the time between 2.58 Ma and 1.80 Ma. It follows the Piacenzian Stage and is followed by the Calabrian Stage.
Calabrian is a subdivision of the Pleistocene Epoch of the geologic time scale, defined as 1.8 Ma—774,000 years ago ± 5,000 years, a period of ~1.026 million years.
The Chibanian, widely known as the Middle Pleistocene, is an age in the international geologic timescale or a stage in chronostratigraphy, being a division of the Pleistocene Epoch within the ongoing Quaternary Period. The Chibanian name was officially ratified in January 2020. 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 Paleolithic over 300 ka.
The Late Pleistocene is an unofficial age in the international geologic timescale in chronostratigraphy, also known as the upper Pleistocene from a stratigraphic perspective. It is intended to be the fourth division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently defined as 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 Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya and 83.6 ± 0.7 mya. The Santonian is preceded by the Coniacian and is followed by the Campanian.
In the geologic timescale, the Sakmarian is an age or stage of the Permian period. It is a subdivision of the Cisuralian Epoch or Series. The Sakmarian lasted between 293.52 and 290.1 million years ago (Ma). It was preceded by the Asselian and followed by the Artinskian.
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 numbering scheme, placing its first year near the beginning of the Holocene geological epoch and the Neolithic Revolution, when humans shifted from a hunter-gatherer lifestyle to agriculture and fixed settlements. The current year by the Gregorian calendar, AD 2024, is 12024 HE in the Holocene calendar. The HE scheme was first proposed by Cesare Emiliani in 1993, though similar proposals to start a new calendar at the same date had been put forward decades earlier.
The Holstein interglacial, also called the Mindel-Riss interglacial (Mindel-Riß-Interglazial) in the Alpine region, is the third to last major interglacial before the Holocene, the present warm period. It followed directly after the Elster glaciation and came before the Saale glaciation, during the Middle Pleistocene. The more precise timing is controversial since Holstein is commonly correlated to two different marine isotope stages, MIS 11 and MIS 9. This ambiguity is much related to the correlation problem described in more detail in the article 'Elster glaciation'.
The Preboreal is an informal stage of the Holocene epoch. It is preceded by the Tarantian and succeeded by the Boreal. It lasted from 10,300 to 9,000 BP in radiocarbon years or 8350 BC to 7050 BC in Gregorian calendar years. It is the first stage of the Holocene epoch. The preboreal oscillation was a short cooling episode within the preboreal.
The Early Pleistocene is an unofficial sub-epoch in the international geologic timescale in chronostratigraphy, representing the earliest division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently estimated to span the time between 2.580 ± 0.005 Ma and 0.773 ± 0.005 Ma. The term Early Pleistocene applies to both the Gelasian Age and the Calabrian Age.
The Meghalayan age is the name given in 2018, by the International Commission on Stratigraphy, to the current age or latest geologic age – or uppermost stage of the Quaternary. It is also the upper, or latest, of three subdivisions of the Holocene epoch or series. This way of breaking down time is based only on geology; for example, it is unrelated to the three-age system of historical periods into which human development is sometimes divided.
In the geologic time scale, the Greenlandian is the earliest age or lowest stage of the Holocene Epoch or Series, part of the Quaternary. Beginning in 11,650 BP and ending with the 8.2-kiloyear event, it is the earliest of three sub-divisions of the Holocene. It was officially ratified by the International Commission on Stratigraphy in June 2018 with the later Northgrippian and Meghalayan Ages/Stages. The lower boundary of the Greenlandian Age is the GSSP sample from the North Greenland Ice Core Project in central Greenland. The Greenlandian GSSP has been correlated with the end of Younger Dryas and a "shift in deuterium excess values".
The Anthropocene Working Group (AWG) is an interdisciplinary research group dedicated to the study of the Anthropocene as a geological time unit. It was established in 2009 as part of the Subcommission on Quaternary Stratigraphy (SQS), a constituent body of the International Commission on Stratigraphy (ICS). As of 2021, the research group features 37 members, with the physical geographer Simon Turner as Secretary and the geologist Colin Neil Waters as chair of the group. The late Nobel Prize-winning Paul Crutzen, who popularized the word 'Anthropocene' in 2000, had also been a member of the group until he died on January 28, 2021. The main goal of the AWG is providing scientific evidence robust enough for the Anthropocene to be formally ratified by the International Union of Geological Sciences (IUGS) as an Epoch within the Geologic time scale.
References
- 1 2 3 Walker, Mike; Head, Martin J.; Berkelhammer, Max; Björck, Svante; Cheng, Hai; Cwynar, Les; Fisher, David; Gkinis, Vasilios; Long, Anthony; Lowe, John; Newnham, Rewi; Rasmussen, Sune Olander; Weiss, Harvey (1 December 2018). "Formal ratification of the subdivision of the Holocene Series/ Epoch (Quaternary System/Period): two new Global Boundary Stratotype Sections and Points (GSSPs) and three new stages/subseries" (PDF). Episodes. Subcommission on Quaternary Stratigraphy (SQS). 41 (4): 213–223. doi: 10.18814/epiiugs/2018/018016 . Retrieved 28 August 2020.This proposal on behalf of the SQS has been approved by the International Commission on Stratigraphy (ICS) and formally ratified by the Executive Committee of the International Union of Geological Sciences (IUGS).
- ↑ Head, Martin J. (17 May 2019). "Formal subdivision of the Quaternary System/Period: Present status and future directions". Quaternary International. 500: 32–51. Bibcode:2019QuInt.500...32H. doi:10.1016/j.quaint.2019.05.018. S2CID 182783922.
- ↑ Cohen, K. M.; Finney, S. C.; Gibbard, P. L.; Fan, J-X. (January 2020). "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. Retrieved 8 January 2021.
- 1 2 International Commission on Stratigraphy. "ICS chart containing the Quaternary and Cambrian GSSPs and new stages (v 2018/07) is now released!" . Retrieved 19 July 2018.
- ↑ Radha-Udayakumar, Ganesh (19 July 2018). "Scientists call our era the Meghalayan Age. Here's what the world was like when it began". India Today. New Delhi: Living Media India Limited. Retrieved 3 January 2021.
- ↑ "'Meghalayan Age': Latest phase in Earth's history named after Indian state, began 4,200 years ago". Scroll.in. 19 July 2018.
- ↑ Amos, Jonathan (18 July 2018). "Welcome to the Meghalayan Age – a new phase in history". BBC News. Retrieved 19 July 2018.
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ka = kiloannum (thousands years ago); Ma = megaannum (millions years ago); Ga = gigaannum (billions years ago). See also: Geologic time scale •  Geologyportal •  Worldportal | |||||||||||||
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