What Appears to Be One Criterion That Scientists Use When Defining the Timing of Geologic Periods?

Organisation that relates geological strata to fourth dimension

This clock representation shows some of the major units of geological time and definitive events of Earth history. The Hadean eon represents the fourth dimension before the fossil record of life on Earth; its upper boundary is at present regarded every bit four.0 Ga (billion years ago).^[one] Other subdivisions reflect the development of life; the Archean and Proterozoic are both eons, the Palaeozoic, Mesozoic and Cenozoic are eras of the Phanerozoic eon. The 3 one thousand thousand year Quaternary flow, the time of recognizable humans, is too small to be visible at this scale.

The geologic time scale (GTS) is a organization of chronological dating that classifies geological strata (stratigraphy) in time. It is used past geologists, paleontologists, and other Earth scientists to depict the timing and relationships of events in geologic history. The time scale was adult through the study and observation of layers of rock and relationships likewise equally the times when dissimilar organisms appeared, evolved and became extinct through the study of fossilized remains and imprints. The table of geologic time spans, presented hither, agrees with the nomenclature, dates and standard color codes ready forth past the International Committee on Stratigraphy (ICS).

Terminology [edit]

The largest catalogued divisions of time are intervals called eons. The showtime eon was the Hadean, starting with the formation of the Earth and lasting about 540 million years until the Archean eon, which is when the Globe had cooled enough for continents and the primeval known life to sally. Later on almost 2.5 billion years, oxygen generated past photosynthesizing unmarried-celled organisms began to appear in the atmosphere, mark the get-go of the Proterozoic. Finally, the Phanerozoic eon encompasses 541 million years of diverse abundance of multicellular life, starting with the appearance of hard beast shells in the fossil record and continuing to the present. The first three eons (i.e. every eon but the Phanerozoic) tin be referred to collectively every bit the Precambrian supereon. This is because of the significance of the Cambrian explosion, a massive diversification of multicellular life forms that took place in the Cambrian period at the beginning of the Phanerozoic. Eons are divided into eras, which are in turn divided into periods, epochs and ages.^{[two] [3]} A polarity chron or just "chron" tin be used as a subdivision of an age, though this is not included in the ICS system.

Eon	Era	Period	Extent, millions of years ago	Duration (millions of years)
Phanerozoic	Cenozoic	Quaternary (Pleistocene/Holocene)	ii.588 to 0	2.588+
		Neogene (Miocene/Pliocene)	23.03 to 2.588	20.4
		Paleogene (Paleocene/Eocene/Oligocene)	66.0 to 23.03	42.9
	Mesozoic	Cretaceous	145.0 to 66.0	79
		Jurassic	201.3 to 145.0	56.three
		Triassic	251.902 to 201.3	50.6
	Paleozoic	Permian	298.9 to 251.902	46.9
		Carboniferous (Mississippian/Pennsylvanian)	358.nine to 298.ix	60
		Devonian	419.2 to 358.9	60.3
		Silurian	443.iv to 419.two	24.2
		Ordovician	485.4 to 443.iv	42
		Cambrian	538.eight to 485.four	53.iv
Proterozoic	Neoproterozoic	Ediacaran	635.0 to 538.eight	96.2
		Cryogenian	720 to 635	85
		Tonian	ane,000 to 720	280
	Mesoproterozoic	Stenian	1,200 to 1,000	200
		Ectasian	i,400 to 1,200	200
		Calymmian	1,600 to 1,400	200
	Paleoproterozoic	Statherian	1,800 to ane,600	200
		Orosirian	two,050 to one,800	250
		Rhyacian	ii,300 to 2,050	250
		Siderian	two,500 to ii,300	200
Archean	Neoarchean	Not officially divided into periods	2,800 to 2,500	300
	Mesoarchean		3,200 to 2,800	400
	Paleoarchean		iii,600 to 3,200	400
	Eoarchean		4,000 to 3,600	400
Hadean	Not officially divided into eras	Not officially divided into periods	From formation of Earth to 4,000	540

Units in geochronology and stratigraphy^[4]

Segments of rock (strata) in chronostratigraphy	Fourth dimension spans in geochronology	Notes to geochronological units
Eonothem	Eon	4 total, one-half a billion years or more
Erathem	Era	10 defined, several hundred million years
System	Period	22 defined, tens to ~one hundred million years
Series	Epoch	34 defined, tens of millions of years
Stage	Age	99 divers, millions of years
Chronozone	Chron	subdivision of an historic period, non used by the ICS timescale

Visual timelines including ages

The following 5 timelines show the geologic fourth dimension scale. The beginning shows the unabridged time from the formation of the Earth to the nowadays, but this gives piddling space for the about contempo eon. Therefore, the second timeline shows an expanded view of the most recent eon. In a like way, the nigh recent era is expanded in the third timeline, the most recent period is expanded in the fourth timeline, and the most recent epoch is expanded in the fifth timeline. Millions of Years (1st, 2nd, third, and 4th) Thousands of years (5th)

Corresponding to eons, eras, periods, epochs and ages, the terms "eonothem", "erathem", "organisation", "serial", "stage" are used to refer to the layers of rock that belong to these stretches of geologic time in World's history.

Geologists qualify these units as "early", "mid", and "late" when referring to time, and "lower", "middle", and "upper" when referring to the corresponding rocks. For case, the Lower Jurassic Series in chronostratigraphy corresponds to the Early Jurassic Epoch in geochronology.^[one] The adjectives are capitalized when the subdivision is formally recognized, and lower case when not; thus "early Miocene" simply "Early on Jurassic."

Era definitions [edit]

The Phanerozoic Eon is divided into 3 eras: the Paleozoic, Mesozoic, and Cenozoic (pregnant "old life", "middle life" and "recent life") that represent the major stages in the macroscopic fossil record. These eras are separated by catastrophic extinction boundaries: the P-T boundary between the Paleozoic and the Mesozoic, and the G-Pg boundary between the Mesozoic and the Cenozoic.^[5] At that place is testify that the P-T boundary was acquired by the eruption of the Siberian Traps, and the Grand-Pg boundary was acquired past the meteorite impact that created the Chicxulub crater.^[6]

The Hadean, Archean and Proterozoic eons were as a whole formerly chosen the Precambrian. This covered the four billion years of Earth history prior to the appearance of hard-shelled animals. More recently, the Archean has been divided into four eras and the Proterozoic has been divided into iii eras.

Period definitions [edit]

The twelve currently recognised periods of the present eon – the Phanerozoic – are defined by the International Commission on Stratigraphy (ICS) by reference to the stratigraphy at particular locations effectually the globe.^[7] In 2004 the Ediacaran Menstruation of the latest Precambrian was divers in similar fashion, and was the starting time such newly designated period in 130 years.^[viii]

A outcome of this approach to the Phanerozoic periods is that the ages of their beginnings and ends tin change from time to fourth dimension equally the absolute age of the chosen rock sequences, which define them, is more precisely adamant.^[ix]

The set of rocks (sedimentary, igneous or metamorphic) formed during a catamenia belong to a chronostratigraphic unit of measurement chosen a system.^[10] For example, the "Jurassic System" of rocks was formed during the "Jurassic Period" (between 201 and 145 million years ago).^[10]

Principles [edit]

Evidence from radiometric dating indicates that Earth is about 4.54 billion years old.^{[11] [12]} The geology or deep fourth dimension of Earth's past has been organized into various units according to events that are thought to accept taken place. Different spans of time on the GTS are ordinarily marked by corresponding changes in the limerick of strata which indicate major geological or paleontological events, such as mass extinctions. For example, the boundary between the Cretaceous flow and the Paleogene period is defined by the Cretaceous–Paleogene extinction event, which marked the demise of the non-avian dinosaurs as well as many other groups of life. Older fourth dimension spans, which predate the reliable fossil record (before the Proterozoic eon), are defined by their accented age.

Geologic units from the aforementioned time merely different parts of the earth oftentimes are non like and incorporate dissimilar fossils, and so the same time-bridge was historically given dissimilar names in unlike locales. For example, in North America, the Lower Cambrian is called the Waucoban series that is then subdivided into zones based on the succession of trilobites. In East asia and Siberia, the same unit is carve up into Alexian, Atdabanian, and Botomian stages. A central aspect of the work of the International Commission on Stratigraphy is to reconcile this conflicting terminology and define universal horizons that can exist used around the world.^[13]

Another planets and moons in the Solar System have sufficiently rigid structures to have preserved records of their own histories, for example, Venus, Mars and the Earth's Moon. Dominantly fluid planets, such equally the gas giants, practice not comparably preserve their history. Autonomously from the Late Heavy Bombardment, events on other planets probably had little direct influence on the Earth, and events on World had correspondingly niggling effect on those planets. Structure of a time calibration that links the planets is, therefore, of only limited relevance to the Earth's time scale, except in a Solar System context. The existence, timing, and terrestrial effects of the Tardily Heavy Bombardment are still a thing of debate.^[a]

History and nomenclature of the time scale [edit]

Graphical representation of Earth's history as a spiral

Early on history [edit]

In Ancient Greece, Aristotle (384–322 BCE) observed that fossils of seashells in rocks resembled those institute on beaches – he inferred that the fossils in rocks were formed by organisms, and he reasoned that the positions of land and sea had inverse over long periods of time. Leonardo da Vinci (1452–1519) concurred with Aristotle's interpretation that fossils represented the remains of ancient life.^[14]

The 11th-century Persian polymath Avicenna (Ibn Sina, died 1037) and the 13th-century Dominican bishop Albertus Magnus (died 1280) extended Aristotle'south explanation into a theory of a petrifying fluid.^[xv] Avicenna also starting time proposed ane of the principles underlying geologic fourth dimension scales, the law of superposition of strata, while discussing the origins of mountains in The Volume of Healing (1027).^[16] The Chinese naturalist Shen Kuo (1031–1095) as well recognized the concept of "deep time".^[17]

Establishment of primary principles [edit]

In the late 17th century Nicholas Steno (1638–1686) pronounced the principles underlying geologic (geological) time scales. Steno argued that rock layers (or strata) were laid down in succession and that each represents a "slice" of time. He besides formulated the constabulary of superposition, which states that any given stratum is probably older than those to a higher place information technology and younger than those below it. While Steno'south principles were simple, applying them proved challenging. Steno's ideas also lead to other important concepts geologists use today, such every bit relative dating. Over the course of the 18th-century geologists realized that:

1. Sequences of strata ofttimes become eroded, distorted, tilted, or even inverted after deposition
2. Strata laid down at the same time in different areas could take entirely unlike appearances
3. The strata of any given area represented only part of Earth's long history

The Neptunist theories popular at this time (expounded by Abraham Werner (1749–1817) in the late 18th century) proposed that all rocks had precipitated out of a single enormous flood. A major shift in thinking came when James Hutton presented his Theory of the Earth; or, an Investigation of the Laws Appreciable in the Limerick, Dissolution, and Restoration of Land Upon the Globe ^[xviii] earlier the Royal Society of Edinburgh in March and April 1785. John McPhee asserts that "as things announced from the perspective of the 20th century, James Hutton in those readings became the founder of modernistic geology".^{[xix] : 95–100} Hutton proposed that the interior of Earth was hot and that this heat was the engine which drove the creation of new rock: land was eroded by air and water and deposited as layers in the sea; heat and so consolidated the sediment into stone and uplifted it into new lands. This theory, known as "Plutonism", stood in contrast to the "Neptunist" flood-oriented theory.

Formulation of geologic time scale [edit]

The first serious attempts to codify a geologic time calibration that could exist applied anywhere on Earth were made in the late 18th century. The most influential of those early attempts (championed by Werner, among others) divided the rocks of Earth's crust into iv types: Primary, Secondary, Tertiary, and Quaternary. Each type of stone, co-ordinate to the theory, formed during a specific catamenia in Earth history. It was thus possible to speak of a "3rd Catamenia" besides as of "Third Rocks." Indeed, "Third" (now Paleogene and Neogene) remained in utilise every bit the name of a geological menstruum well into the 20th century and "Fourth" remains in formal employ as the name of the current period.

The identification of strata by the fossils they independent, pioneered by William Smith, Georges Cuvier, Jean d'Omalius d'Halloy, and Alexandre Brongniart in the early 19th century, enabled geologists to divide Earth history more precisely. It too enabled them to correlate strata across national (or fifty-fifty continental) boundaries. If two strata (all the same afar in space or different in composition) independent the aforementioned fossils, chances were good that they had been laid down at the same time. Detailed studies betwixt 1820 and 1850 of the strata and fossils of Europe produced the sequence of geologic periods still used today.

Naming of geologic periods, eras and epochs [edit]

Early work on developing the geologic fourth dimension scale was dominated by British geologists, and the names of the geologic periods reflect that dominance. The "Cambrian", (the classical name for Wales) and the "Ordovician" and "Silurian", named later aboriginal Welsh tribes, were periods divers using stratigraphic sequences from Wales.^{[19] : 113–114} The "Devonian" was named for the English county of Devon, and the proper noun "Carboniferous" was an adaptation of "the Coal Measures", the onetime British geologists' term for the same set of strata. The "Permian" was named after the region of Perm in Russia, considering it was defined using strata in that region by Scottish geologist Roderick Murchison. Nonetheless, some periods were divers by geologists from other countries. The "Triassic" was named in 1834 by a German geologist Friedrich Von Alberti from the three distinct layers (Latin trias significant triad) – blood-red beds, capped by chalk, followed past black shales – that are institute throughout Germany and Northwest Europe, called the 'Trias'. The "Jurassic" was named past a French geologist Alexandre Brongniart for the all-encompassing marine limestone exposures of the Jura Mountains. The "Cretaceous" (from Latin creta meaning 'chalk') equally a separate period was beginning divers by Belgian geologist Jean d'Omalius d'Halloy in 1822, using strata in the Paris basin^[xx] and named for the extensive beds of chalk (calcium carbonate deposited by the shells of marine invertebrates) found in Western Europe.

British geologists were too responsible for the grouping of periods into eras and the subdivision of the Tertiary and Fourth periods into epochs. In 1841 John Phillips published the showtime global geologic time scale based on the types of fossils found in each era. Phillips' scale helped standardize the use of terms like Paleozoic ("sometime life"), which he extended to cover a larger period than it had in previous usage, and Mesozoic ("middle life"), which he invented.^[21]

Dating of fourth dimension scales [edit]

When William Smith and Sir Charles Lyell first recognized that stone strata represented successive time periods, time scales could be estimated only very imprecisely since estimates of rates of change were uncertain. While creationists had been proposing dates of around six or seven thou years for the age of Earth based on the Bible, early geologists were suggesting millions of years for geologic periods, and some were even suggesting a virtually infinite age for Earth.^{[ citation needed ]} Geologists and paleontologists constructed the geologic tabular array based on the relative positions of different strata and fossils, and estimated the time scales based on studying rates of various kinds of weathering, erosion, sedimentation, and lithification. Until the discovery of radioactivity in 1896 and the development of its geological applications through radiometric dating during the first half of the 20th century, the ages of various rock strata and the age of World were the subject of considerable debate.

The first geologic time scale that included absolute dates was published in 1913 past the British geologist Arthur Holmes.^[22] He profoundly furthered the newly created discipline of geochronology and published the world-renowned volume The Age of the Earth in which he estimated World's historic period to exist at least 1.6 billion years.^[23]

In a steady endeavour ongoing since 1974, the International Committee on Stratigraphy has been working to correlate the world's local stratigraphic record into one uniform planet-wide benchmarked arrangement.^[24]

In 1977, the Global Committee on Stratigraphy (now the International Committee on Stratigraphy) began to define global references known as GSSP (Global Boundary Stratotype Sections and Points) for geologic periods and faunal stages. The committee's work is described in the 2012 geologic time scale of Gradstein et al.^[ix] A UML model for how the timescale is structured, relating it to the GSSP, is also available.^[25]

Correlation issues [edit]

American geologists have long considered the Mississippian and Pennsylvanian to be periods in their ain correct though the ICS now recognises them both as "subperiods" of the Carboniferous Period recognised past European geologists.^[26] Cases like this in China, Russia and even New Zealand with other geological eras has slowed the uniform organization of the stratigraphic record.^[27]

The Anthropocene [edit]

Popular culture and a growing number of scientists employ the term "Anthropocene" informally to label the current epoch in which nosotros are living.^[28] The term was coined past Paul Crutzen and Eugene Stoermer in 2000 to depict the current time in which humans accept had an enormous touch on on the environs. It has evolved to describe an "epoch" starting some time in the past and on the whole defined by anthropogenic carbon emissions and production and consumption of plastic goods that are left in the ground.^[29]

Critics of this term say that the term should not be used because it is difficult, if not nearly impossible, to define a specific time when humans started influencing the rock strata – defining the start of an epoch.^[thirty]

The ICS has not officially approved the term as of September 2015^[update].^[31] The Anthropocene Working Group met in Oslo in April 2016 to consolidate prove supporting the argument for the Anthropocene as a truthful geologic epoch.^[31] Evidence was evaluated and the group voted to recommend "Anthropocene" as the new geological age in August 2016.^[32] Should the International Committee on Stratigraphy approve the recommendation, the proposal to adopt the term will have to be ratified by the International Union of Geological Sciences before its formal adoption every bit part of the geologic time scale.^[33]

Notable period changes [edit]

• Changes in recent years have included the abandonment of the sometime 3rd Period in favour of the Paleogene and succeeding Neogene periods. This remains controversial.^[34]
• The abandonment of the 4th flow was as well considered but it has been retained for continuity reasons.^[35]
• Even earlier in the history of the science, the Tertiary was considered to be an "era" and its subdivisions (Paleocene, Eocene, Oligocene, Miocene and Pliocene) were themselves referred to equally "periods"^[36] merely they now enjoy the status of "epochs" inside the more than recently delineated Paleogene and Neogene periods.^[7]

Table of geologic fourth dimension [edit]

The following table summarizes the major events and characteristics of the periods of fourth dimension making upwardly the geologic fourth dimension calibration. This tabular array is arranged with the most recent geologic periods at the elevation, and the oldest at the lesser. The elevation of each table entry does non correspond to the duration of each subdivision of time.

The content of the tabular array is based on the official geologic time scale of the International Commission on Stratigraphy (ICS).^[one] The electric current version is provided by the ICS online.^[37] The ICS provides an online interactive version of this nautical chart, ics-chart, based on a service delivering a machine-readable Resource Description Framework/Web Ontology Language representation of the timescale, which is available through the Commission for the Direction and Awarding of Geoscience Data GeoSciML projection equally a service^[38] and at a SPARQL end-indicate.^{[39] [40]}

The chronostratrigraphic epoch/subepoch names are altered to the early/tardily format from lower/upper of the equivalent geochronologic series/subseries every bit is recommended by the ICS.^[2] Subseries/subepochs for the Neogene accept been ratified as of 13 Oct 2021.^[41]

This table is not to calibration, and even though the Phanerozoic eon looks longer than the remainder, it merely spans 500 million years, whilst the previous iii eons (or the Precambrian supereon) collectively span over iii.v billion years. This bias toward the most contempo eon is due to the relative lack of information near events that occurred during the first iii eons (or supereon) compared to the current eon (the Phanerozoic).^{[42] [43]}

The proposed Anthropocene epoch is not included.

Supereon	Eon	Era	Period[b]	Epoch	Age[c]	Major events	Beginning, one thousand thousand years ago[c]
n/a[d]	Phanerozoic	Cenozoic[e]	4th	Holocene	Meghalayan	4.2-kiloyear event, Austronesian expansion, increasing industrial CO2.	0.0042*
					Northgrippian	8.2-kiloyear upshot, Holocene climatic optimum. Sea level flooding of Doggerland and Sundaland. Sahara becomes a desert. End of Stone Historic period and get-go of recorded history. Humans finally expand into the Arctic Archipelago and Greenland.	0.0082*
					Greenlandian	Climate stabilizes. Electric current interglacial and Holocene extinction begins. Agriculture begins. Humans spread beyond the moisture Sahara and Arabia, the Farthermost Due north, and the Americas (mainland and the Caribbean).	0.0117*
				Pleistocene	Tardily ('Tarantian')	Eemian interglacial, last glacial menstruation, ending with Younger Dryas. Toba eruption. Pleistocene megafauna (including the last terror birds) extinction. Humans expand into Near Oceania and the Americas.	0.129
					Chibanian	Mid-Pleistocene Transition occurs, high aamplitude 100 ka glacial cycles. Rise of Homo sapiens.	0.774*
					Calabrian	Further cooling of the climate. Giant terror birds go extinct. Spread of Homo erectus across Afro-Eurasia.	one.eight*
					Gelasian	Start of Fourth glaciations and unstable climate.[46] Ascent of the Pleistocene megafauna and Human being habilis.	two.58*
			Neogene	Pliocene	Piacenzian	Greenland ice canvass develops[47] every bit the cold slowly intensifies towards the Pleistocene. Atmospheric O2 and CO2 content reaches present twenty-four hours levels while landmasses also attain their current locations (e.g. the Isthmus of Panama joins the North and Due south Americas, while allowing a faunal interchange). The last non-marsupial metatherians get extinct. Australopithecus common in E Africa; Stone Age begins.[48]	3.6*
					Zanclean	Zanclean flooding of the Mediterranean Bowl. Cooling climate continues from the Miocene. First equines and elephantines. Ardipithecus in Africa.[48]	5.333*
				Miocene	Messinian	Messinian Event with hypersaline lakes in empty Mediterranean Basin. Moderate icehouse climate, punctuated past ice ages and re-establishment of East Antarctic Water ice Canvas. Choristoderes, the final not-crocodilian crocodylomorphs and creodonts become extinct. After separating from gorilla ancestors, chimpanzee and human ancestors gradually separate; Sahelanthropus and Orrorin in Africa.	vii.246*
					Tortonian		xi.63*
					Serravallian	Eye Miocene climate optimum temporarily provides a warm climate.[49] Extinctions in eye Miocene disruption, decreasing shark multifariousness. Offset hippos. Ancestor of great apes.	13.82*
					Langhian		15.97
					Burdigalian	Orogeny in Northern Hemisphere. Starting time of Kaikoura Orogeny forming Southern Alps in New Zealand. Widespread forests slowly draw in massive amounts of COii, gradually lowering the level of atmospheric COtwo from 650 ppmv down to around 100 ppmv during the Miocene.[l] [f] Modernistic bird and mammal families become recognizable. The last of the primitive whales go extinct. Grasses go ubiquitous. Ancestor of apes, including humans.[51] Afro-Arabia collides with Eurasia, fully forming the Alpide Belt and closing the Tethys Sea, while allowing a faunal interchange. At the same time, Afro-Arabia splits into Africa and West Asia.	20.44
					Aquitanian		23.03*
			Paleogene	Oligocene	Chattian	Grande Coupure extinction. Start of widespread Antarctic glaciation.[52] Rapid development and diversification of fauna, especially mammals (e.g. first macropods and seals). Major evolution and dispersal of modern types of flowering plants. Cimolestans, miacoids and condylarths become extinct. First neocetes (modern, fully aquatic whales) appear.	28.1
					Rupelian		33.9*
				Eocene	Priabonian	Moderate, cooling climate. Archaic mammals (e.grand. creodonts, miacoids, "condylarths" etc.) flourish and continue to develop during the epoch. Appearance of several "modern" mammal families. Archaic whales and sea cows diversify subsequently returning to water. Birds continue to diversify. Start kelp, diprotodonts, bears and simians. The multituberculates and leptictidans go extinct past the finish of the epoch. Reglaciation of Antarctica and formation of its ice cap; Terminate of Laramide and Sevier Orogenies of the Rocky Mountains in Northward America. Hellenic Orogeny begins in Greece and Aegean Sea.	37.8*
					Bartonian		41.2
					Lutetian		47.8*
					Ypresian	Two transient events of global warming (PETM and ETM-2) and warming climate until the Eocene Climatic Optimum. The Azolla effect decreased COii levels from 3500 ppm to 650 ppm, setting the stage for a long flow of cooling.[l] [f] Greater Bharat collides with Eurasia and starts Himalayan Orogeny (allowing a biotic interchange) while Eurasia completely separates from North America, creating the North Atlantic Ocean. Maritime Southeast Asia diverges from the residual of Eurasia. First passerines, ruminants, pangolins, bats and truthful primates.	56*
				Paleocene	Thanetian	Starts with Chicxulub impact and the K-Pg extinction event, wiping out all not-avian dinosaurs and pterosaurs, most marine reptiles, many other vertebrates (e.grand. many Laurasian metatherians), most cephalopods (only Nautilidae and Coleoidea survived) and many other invertebrates. Climate tropical. Mammals and birds (avians) diversify rapidly into a number of lineages following the extinction event (while the marine revolution stops). Multituberculates and the outset rodents widespread. Offset large birds (due east.g. ratites and terror birds) and mammals (upwardly to conduct or modest hippo size). Alpine orogeny in Europe and Asia begins. Beginning proboscideans and plesiadapiformes (stalk primates) announced. Some marsupials drift to Commonwealth of australia.	59.ii*
					Selandian		61.six*
					Danian		66*
		Mesozoic	Cretaceous	Tardily	Maastrichtian	Flowering plants proliferate (after developing many features since the Carboniferous), along with new types of insects, while other seed plants (gymnosperms and seed ferns) decline. More modern teleost fish begin to announced. Ammonoids, belemnites, rudist bivalves, sea urchins and sponges all common. Many new types of dinosaurs (eastward.g. tyrannosaurs, titanosaurs, hadrosaurs, and ceratopsids) evolve on land, while crocodilians appear in water and probably crusade the last temnospondyls to die out; and mosasaurs and modernistic types of sharks appear in the body of water. The revolution started by marine reptiles and sharks reaches its top, though ichthyosaurs vanish few million years after being heavily reduced at the Bonarelli Event. Toothed and toothless avian birds coexist with pterosaurs. Modern monotremes, metatherian (including marsupials, who migrate to South America) and eutherian (including placentals, leptictidans and cimolestans) mammals appear while the last non-mammalian cynodonts die out. Outset terrestrial crabs. Many snails become terrestrial. Farther breakup of Gondwana creates Due south America, Afro-Arabia, Antarctica, Oceania, Republic of madagascar, Greater India, and the South Atlantic, Indian and Antarctic Oceans and the islands of the Indian (and some of the Atlantic) Ocean. Beginning of Laramide and Sevier Orogenies of the Rocky Mountains. Atmospheric oxygen and carbon dioxide levels similar to present day. Acritarchs disappear. Climate initially warm, only afterward information technology cools.	72.1 ± 0.2*
					Campanian		83.6 ± 0.2
					Santonian		86.three ± 0.5*
					Coniacian		89.viii ± 0.3
					Turonian		93.9*
					Cenomanian		100.5*
				Early	Albian		~113*
					Aptian		~125
					Barremian		~129.four
					Hauterivian		~132.ix*
					Valanginian		~139.8
					Berriasian		~145
			Jurassic	Belatedly	Tithonian	Climate becomes humid again. Gymnosperms (especially conifers, cycads and cycadeoids) and ferns mutual. Dinosaurs, including sauropods, carnosaurs, stegosaurs and coelurosaurs, get the dominant land vertebrates. Mammals diversify into shuotheriids, australosphenidans, eutriconodonts, multituberculates, symmetrodonts, dryolestids and boreosphenidans but mostly remain minor. First birds, lizards, snakes and turtles. Commencement chocolate-brown algae, rays, shrimps, crabs and lobsters. Parvipelvian ichthyosaurs and plesiosaurs various. Rhynchocephalians throughout the world. Bivalves, ammonoids and belemnites abundant. Sea urchins very mutual, along with crinoids, starfish, sponges, and terebratulid and rhynchonellid brachiopods. Breakup of Pangaea into Laurasia and Gondwana, with the latter also breaking into two principal parts; the Pacific and Chill Oceans grade. Tethys Ocean forms. Nevadan orogeny in Due north America. Rangitata and Cimmerian orogenies taper off. Atmospheric CO2 levels 3–iv times the present day levels (1200–1500 ppmv, compared to today'due south 400 ppmv[50] [f]). Crocodylomorphs (final pseudosuchians) seek out an aquatic lifestyle. Mesozoic marine revolution continues from late Triassic. Tentaculitans disappear.	152.ane ± 0.9
					Kimmeridgian		157.3 ± ane.0*
					Oxfordian		163.5 ± 1.0
				Middle	Callovian		166.i ± 1.2
					Bathonian		168.three ± 1.three*
					Bajocian		170.3 ± 1.4*
					Aalenian		174.1 ± 1.0*
				Early	Toarcian		182.seven ± 0.7*
					Pliensbachian		190.8 ± 1.0*
					Sinemurian		199.iii ± 0.3*
					Hettangian		201.three ± 0.2*
			Triassic	Late	Rhaetian	Archosaurs dominant on land as pseudosuchians and in the air as pterosaurs. Dinosaurs besides arise from bipedal archosaurs. Ichthyosaurs and nothosaurs (a group of sauropterygians) boss large marine brute. Cynodonts become smaller and nocturnal, somewhen becoming the first true mammals, while other remaining synapsids die out. Rhynchosaurs (archosaur relatives) also common. Seed ferns called Dicroidium remained common in Gondwana, before being replaced by advanced gymnosperms. Many large aquatic temnospondyl amphibians. Ceratitidan ammonoids extremely common. Modern corals and teleost fish appear, equally do many modernistic insect orders and suborders. Showtime starfish. Andean Orogeny in Due south America. Cimmerian Orogeny in Asia. Rangitata Orogeny begins in New Zealand. Hunter-Bowen Orogeny in Northern Commonwealth of australia, Queensland and New South Wales ends, (c. 260–225 Ma). Carnian pluvial effect occurs around 234-232 Ma, assuasive the outset dinosaurs and lepidosaurs (including rhynchocephalians) to radiate. Triassic-Jurassic extinction event occurs 201 Ma, wiping out all conodonts and the final parareptiles, many marine reptiles (east.g. all sauropterygians except plesiosaurs and all ichthyosaurs except parvipelvians), all crocopodans except crocodylomorphs, pterosaurs, and dinosaurs, and many ammonoids (including the whole Ceratitida), bivalves, brachiopods, corals and sponges. Beginning diatoms.[53]	~208.5
					Norian		~227
					Carnian		~237*
				Middle	Ladinian		~242*
					Anisian		247.two
				Early	Olenekian		251.2
					Induan		251.902 ± 0.024*
		Paleozoic	Permian	Lopingian	Changhsingian	Landmasses unite into supercontinent Pangaea, creating the Urals, Ouachitas and Appalachians, amongst other mount ranges (the superocean Panthalassa or Proto-Pacific also forms). Stop of Permo-Carboniferous glaciation. Hot and dry out climate. A possible drop in oxygen levels. Synapsids (pelycosaurs and therapsids) become widespread and dominant, while parareptiles and temnospondyl amphibians remain common, with the latter probably giving rise to modern amphibians in this menstruation. In the mid-Permian, lycophytes are heavily replaced by ferns and seed plants. Beetles and flies evolve. The very large arthropods and not-tetrapod tetrapodomorphs go extinct. Marine life flourishes in warm shallow reefs; productid and spiriferid brachiopods, bivalves, forams, ammonoids (including goniatites), and orthoceridans all abundant. Crown reptiles ascend from earlier diapsids, and separate into the ancestors of lepidosaurs, kuehneosaurids, choristoderes, archosaurs, testudinatans, ichthyosaurs, thalattosaurs, and sauropterygians. Cynodonts evolve from larger therapsids. Olson's Extinction (273 Ma), End-Capitanian extinction (260 Ma), and Permian-Triassic extinction event (252 Ma) occur one subsequently another: more than 80% of life on Earth becomes extinct in the lattermost, including most retarian plankton, corals (Tabulata and Rugosa dice out fully), brachiopods, bryozoans, gastropods, ammonoids (the goniatites die off fully), insects, parareptiles, synapsids, amphibians, and crinoids (simply articulates survived), and all eurypterids, trilobites, graptolites, hyoliths, edrioasteroid crinozoans, blastoids and acanthodians. Ouachita and Innuitian orogenies in North America. Uralian orogeny in Europe/Asia tapers off. Altaid orogeny in Asia. Hunter-Bowen Orogeny on Australian continent begins (c. 260–225 Ma), forming the MacDonnell Ranges.	254.xiv ± 0.07*
					Wuchiapingian		259.i ± 0.21*
				Guadalupian	Capitanian		265.i ± 0.sixteen*
					Wordian		268.viii ± 0.4*
					Roadian		272.95 ± 0.14*
				Cisuralian	Kungurian		283.five ± 0.6
					Artinskian		290.1 ± 0.26*
					Sakmarian		295 ± 0.17*
					Asselian		298.9 ± 0.15*
			Carbon- iferous[k]	Pennsylvanian	Gzhelian	Winged insects radiate suddenly; some (esp. Protodonata and Palaeodictyoptera) of them too some millipedes and scorpions become very big. First coal forests (calibration copse, ferns, society trees, behemothic horsetails, Cordaites, etc.). Higher atmospheric oxygen levels. Water ice Historic period continues to the Early Permian. Goniatites, brachiopods, bryozoa, bivalves, and corals plentiful in the seas and oceans. First woodlice. Testate forams proliferate. Euramerica collides with Gondwana and Siberia-Kazakhstania, the latter of which forms Laurasia and the Uralian orogeny. Variscan orogeny continues (these collisions created orogenies, and ultimately Pangaea). Amphibians (eastward.g. temnospondyls) spread in Euramerica, with some becoming the first amniotes. Carboniferous Rainforest Plummet occurs, initiating a dry climate which favors amniotes over amphibians. Amniotes diversify speedily into synapsids, parareptiles, cotylosaurs, protorothyridids and diapsids. Rhizodonts remained common earlier they died out by the finish of the period. Get-go sharks.	303.7 ± 0.i
Kasimovian	307 ± 0.1
Moscovian	315.two ± 0.2
Bashkirian	323.2 ± 0.four*
Mississippian	Serpukhovian			Large lycopodian archaic trees flourish and amphibious eurypterids live among coal-forming coastal swamps, radiating significantly one last time. Showtime gymnosperms. First holometabolous, paraneopteran, polyneopteran, odonatopteran and ephemeropteran insects and first barnacles. Commencement five-digited tetrapods (amphibians) and land snails. In the oceans, bony and cartilaginous fishes are dominant and diverse; echinoderms (especially crinoids and blastoids) arable. Corals, bryozoans, orthoceridans, goniatites and brachiopods (Productida, Spiriferida, etc.) recover and become very common over again, simply trilobites and nautiloids decline. Glaciation in East Gondwana continues from Late Devonian. Tuhua Orogeny in New Zealand tapers off. Some lobe finned fish chosen rhizodonts become abundant and dominant in freshwaters. Siberia collides with a different small continent, Kazakhstania.	330.ix ± 0.2
	Viséan				346.seven ± 0.iv*
	Tournaisian				358.ix ± 0.four*
Devonian	Late		Famennian	First lycopods, ferns, seed plants (seed ferns, from earlier progymnosperms), first copse (the progymnosperm Archaeopteris), and start winged insects (palaeoptera and neoptera). Strophomenid and atrypid brachiopods, rugose and tabulate corals, and crinoids are all abundant in the oceans. First fully coiled cephalopods (Ammonoidea and Nautilida, independently) with the onetime grouping very arable (especially goniatites). Trilobites and ostracoderms decline, while jawed fishes (placoderms, lobe-finned and ray-finned bony fish, and acanthodians and early cartilaginous fish) proliferate. Some lobe finned fish transform into digited fishapods, slowly becoming amphibious. The last non-trilobite artiopods dice off. Beginning decapods (like prawns) and isopods. Pressure from jawed fishes crusade eurypterids to decline and some cephalopods to lose their shells while anomalocarids vanish. "Quondam Red Continent" of Euramerica persists after forming in the Caledonian orogeny. Showtime of Acadian Orogeny for Anti-Atlas Mountains of North Africa, and Appalachian Mountains of North America, also the Antler, Variscan, and Tuhua orogenies in New Zealand. A series of extinction events, including the massive Kellwasser and Hangenberg ones, wipe out many acritarchs, corals, sponges, molluscs, trilobites, eurypterids, graptolites, brachiopods, crinozoans (e.k. all cystoids), and fish, including all placoderms and ostracoderms.	372.2 ± 1.vi*
			Frasnian		382.7 ± 1.half-dozen*
	Middle		Givetian		387.seven ± 0.8*
			Eifelian		393.3 ± 1.2*
	Early		Emsian		407.six ± 2.6*
			Pragian		410.viii ± 2.8*
			Lochkovian		419.2 ± three.2*
Silurian	Pridoli		Ozone layer thickens. Outset vascular plants and fully terrestrialized arthropods: myriapods, hexapods (including insects), and arachnids. Eurypterids diversify rapidly, condign widespread and dominant. Cephalopods keep to flourish. True jawed fishes, forth with ostracoderms, besides roam the seas. Tabulate and rugose corals, brachiopods (Pentamerida, Rhynchonellida, etc.), cystoids and crinoids all arable. Trilobites and molluscs various; graptolites non as varied. Three pocket-size extinction events. Some echinoderms go extinct. Beginning of Caledonian Orogeny (collision betwixt Laurentia, Baltica and one of the formerly pocket-size Gondwanan terranes) for hills in England, Ireland, Wales, Scotland, and the Scandinavian Mountains. Also continued into Devonian menses as the Acadian Orogeny, above (thus Euramerica forms). Taconic Orogeny tapers off. Icehouse menstruation ends late in this menstruum after starting in Late Ordovician. Lachlan Orogeny on Australian continent tapers off.	423 ± 2.3*
	Ludlow	Ludfordian		425.half-dozen ± 0.9*
		Gorstian		427.4 ± 0.five*
	Wenlock	Homerian		430.five ± 0.7*
		Sheinwoodian		433.4 ± 0.8*
	Llandovery	Telychian		438.5 ± 1.1*
		Aeronian		440.8 ± 1.2*
		Rhuddanian		443.8 ± i.5*
Ordovician	Belatedly	Hirnantian	The Great Ordovician Biodiversification Event occurs every bit plankton increase in number: invertebrates diversify into many new types (especially brachiopods and molluscs; e.chiliad. long straight-shelled cephalopods like the long lasting and diverse Orthocerida). Early corals, articulate brachiopods (Orthida, Strophomenida, etc.), bivalves, cephalopods (nautiloids), trilobites, ostracods, bryozoans, many types of echinoderms (blastoids, cystoids, crinoids, sea urchins, sea cucumbers, and star-like forms, etc.), branched graptolites, and other taxa all common. Acritarchs still persist and mutual. Cephalopods become dominant and common, with some trending toward a coiled beat out. Anomalocarids decline. Mysterious tentaculitans appear. Offset eurypterids and ostracoderm fish appear, the latter probably giving rise to the jawed fish at the end of the period. First uncontroversial terrestrial fungi and fully terrestrialized plants. Water ice historic period at the end of this menses, as well as a series of mass extinction events, killing off some cephalopods and many brachiopods, bryozoans, echinoderms, graptolites, trilobites, bivalves, corals and conodonts.	445.2 ± 1.4*
		Katian		453 ± 0.seven*
		Sandbian		458.4 ± 0.ix*
	Center	Darriwilian		467.3 ± 1.ane*
		Dapingian		470 ± 1.four*
	Early	Floian (formerly Arenig)		477.7 ± one.four*
		Tremadocian		485.4 ± 1.nine*
Cambrian	Furongian	Stage x	Major diversification of (fossils mainly show bilaterian) life in the Cambrian Explosion as oxygen levels increase. Numerous fossils; nearly modern beast phyla (including arthropods, molluscs, annelids, echinoderms, hemichordates and chordates) appear. Reef-edifice archaeocyathan sponges initially abundant, so vanish. Stromatolites replace them, but quickly fall prey to the Agronomic revolution, when some animals started burrowing through the microbial mats (affecting some other animals as well). Get-go artiopods (including trilobites), priapulid worms, inarticulate brachiopods (unhinged lampshells), hyoliths, bryozoans, graptolites, pentaradial echinoderms (e.g. blastozoans, crinozoans and eleutherozoans), and numerous other animals. Anomalocarids are dominant and giant predators, while many Ediacaran animate being dice out. Crustaceans and molluscs diversify rapidly. Prokaryotes, protists (e.thou., forams), algae and fungi continue to present twenty-four hours. Outset vertebrates from earlier chordates. Petermann Orogeny on the Australian continent tapers off (550–535 Ma). Ross Orogeny in Antarctica. Delamerian Orogeny (c. 514–490 Ma) and Lachlan Orogeny (c. 540–440 Ma) on Australian continent. Some small terranes divide off from Gondwana. Atmospheric CO2 content roughly 15 times present-day (Holocene) levels (6000 ppmv compared to today's 400 ppmv)[50] [f] Arthropods and streptophyta get-go colonizing state. 3 extinction events occur 517, 502 & 488 Ma, the first and concluding of which wipe out many of the anomalocarids, artiopods, hyoliths, brachiopods, molluscs, and conodonts (early jawless vertebrates).	~489.5
		Jiangshanian		~494*
		Paibian		~497*
	Miaolingian	Guzhangian		~500.5*
		Drumian		~504.5*
		Wuliuan		~509
	Serial two	Stage four		~514
		Stage 3		~521
	Terreneuvian	Phase 2		~529
		Fortunian		~541 ± 1.0*
Precambrian[h]	Proterozoic[i]	Neoproterozoic[i]	Ediacaran	Adept fossils of primitive animals. Ediacaran biota flourish worldwide in seas, possibly appearing after an explosion, perchance caused past a big-calibration oxidation event.[54] First vendozoans (unknown analogousness among animals), cnidarians and bilaterians. Enigmatic vendozoans include many soft-jellied creatures shaped like bags, disks, or quilts (like Dickinsonia). Simple trace fossils of possible worm-like Trichophycus, etc.Taconic Orogeny in North America. Aravalli Range orogeny in Indian subcontinent. Starting time of Pan-African Orogeny, leading to the formation of the short-lived Ediacaran supercontinent Pannotia, which by the cease of the period breaks upwards into Laurentia, Baltica, Siberia and Gondwana. Petermann Orogeny forms on Australian continent. Beardmore Orogeny in Antarctica, 633–620 Ma. Ozone layer forms. An increase in oceanic mineral levels.			~635*
			Cryogenian	Possible "Snowball Earth" period. Fossils still rare. Rodinia landmass begins to break upwards. Late Ruker / Nimrod Orogeny in Antarctica tapers off. First uncontroversial animal fossils. Beginning hypothetical terrestrial fungi[55] and streptophyta.[56]			~720[j]
			Tonian	Rodinia supercontinent persists. Sveconorwegian orogeny ends. Grenville Orogeny tapers off in Due north America. Lake Ruker / Nimrod Orogeny in Antarctica, 1,000 ± 150 Ma. Edmundian Orogeny (c. 920 – 850 Ma), Gascoyne Complex, Western Australia. Deposition of Adelaide Superbasin and Centralian Superbasin begins on Australian continent. Starting time hypothetical animals (from holozoans) and terrestrial algal mats. Many endosymbiotic events concerning scarlet and light-green algae occur, transferring plastids to ochrophyta (east.1000. diatoms, brown algae), dinoflagellates, cryptophyta, haptophyta, and euglenids (the events may have begun in the Mesoproterozoic)[57] while the beginning retarians (e.g. forams) also appear: eukaryotes diversify rapidly, including algal, eukaryovoric and biomineralized forms. Trace fossils of simple multi-celled eukaryotes.			1000[j]
		Mesoproterozoic[i]	Stenian	Narrow highly metamorphic belts due to orogeny as Rodinia forms, surrounded by the Pan-African Bounding main. Sveconorwegian orogeny starts. Late Ruker / Nimrod Orogeny in Antarctica perhaps begins. Musgrave Orogeny (c. ane,080 Ma), Musgrave Block, Central Australia. Stromatolites decline as algae proliferate.			1200[j]
			Ectasian	Platform covers continue to aggrandize. Algal colonies in the seas. Grenville Orogeny in North America. Columbia breaks upward.			1400[j]
			Calymmian	Platform covers expand. Barramundi Orogeny, McArthur Basin, Northern Australia, and Isan Orogeny, c. one,600 Ma, Mount Isa Block, Queensland. Get-go archaeplastidans (the first eukaryotes with plastids from cyanobacteria; eastward.g. red and greenish algae) and opisthokonts (giving rise to the first fungi and holozoans). Acritarchs (remains of marine algae possibly) start appearing in the fossil record.			1600[j]
		Paleoproterozoic[i]	Statherian	First uncontroversial eukaryotes: protists with nuclei and endomembrane organisation. Columbia forms as the second undisputed earliest supercontinent. Kimban Orogeny in Australian continent ends. Yapungku Orogeny on Yilgarn craton, in Western Australia. Mangaroon Orogeny, 1,680–ane,620 Ma, on the Gascoyne Complex in Western Australia. Kararan Orogeny (1,650 Ma), Gawler Craton, Southward Australia. Oxygen levels drop once again.			1800[j]
			Orosirian	The atmosphere becomes much more oxygenic while more cyanobacterial stromatolites announced. Vredefort and Sudbury Bowl asteroid impacts. Much orogeny. Penokean and Trans-Hudsonian Orogenies in North America. Early on Ruker Orogeny in Antarctica, 2,000–1,700 Ma. Glenburgh Orogeny, Glenburgh Terrane, Australian continent c. 2,005–one,920 Ma. Kimban Orogeny, Gawler craton in Australian continent begins.			2050[j]
			Rhyacian	Bushveld Igneous Complex forms. Huronian glaciation. Starting time hypothetical eukaryotes. Multicellular Francevillian biota. Kenorland disassembles.			2300[j]
			Siderian	Great Oxidation Event (due to cyanobacteria) increases oxygen. Sleaford Orogeny on Australian continent, Gawler Craton ii,440–2,420 Ma.			2500[j]
	Archean[i]	Neoarchean[i]	Stabilization of most modern cratons; possible pall overturn event. Insell Orogeny, ii,650 ± 150 Ma. Abitibi greenstone chugalug in nowadays-day Ontario and Quebec begins to class, stabilizes past two,600 Ma. First uncontroversial supercontinent, Kenorland, and first terrestrial prokaryotes.				2800[j]
		Mesoarchean[i]	First stromatolites (probably colonial phototrophic bacteria, like blue-green alga). Oldest macrofossils. Humboldt Orogeny in Antarctica. Blake River Megacaldera Circuitous begins to form in nowadays-day Ontario and Quebec, ends past roughly two,696 Ma.				3200[j]
		Paleoarchean[i]	Prokaryotic archaea (e.g. methanogens) and bacteria (e.g. blue-green alga) diversify quickly, along with early viruses. Showtime known phototrophic leaner. Oldest definitive microfossils. First microbial mats. Oldest cratons on Globe (such as the Canadian Shield and the Pilbara Craton) may accept formed during this flow.[g] Rayner Orogeny in Antarctica.				3600[j]
		Eoarchean[i]	Starting time uncontroversial living organisms: at first protocells with RNA-based genes around 4000 Ma, after which true cells (prokaryotes) evolve along with proteins and Dna-based genes around 3800 Ma. The terminate of the Tardily Heavy Bombardment. Napier Orogeny in Antarctica, 4,000 ± 200 Ma.				~4000
	Hadean[i] [l]	Early Imbrian (Neohadean) (unofficial)[i] [grand]	This era overlaps the showtime of the Late Heavy Bombardment of the Inner Solar Arrangement, produced peradventure by the planetary migration of Neptune into the Kuiper belt every bit a event of orbital resonances between Jupiter and Saturn. Oldest known stone (iv,031 to 3,580 Ma).[59]				4130[60]
		Nectarian (Mesohadean) (unofficial)[i] [k]	Possible first appearance of plate tectonics. This unit gets its name from the lunar geologic timescale when the Nectaris Basin and other greater lunar basins course by big impact events. Commencement hypothetical life forms.				4280[60]
		Basin Groups (Paleohadean) (unofficial)[i] [m]	End of the Early Bombardment Phase. Oldest known mineral (Zircon, 4,404 ± 8 Ma).[61] Asteroids and comets bring h2o to Globe, forming the first oceans.[62]				4533[threescore]
		Ambiguous (Eohadean) (unofficial)[i] [m]	Formation of Moon (4,533 to iv,527 Ma), probably from behemothic impact, since the end of this era. Formation of World (4,570 to iv,567.17 Ma), Early Bombardment Stage begins. Germination of Sun (4,680 to four,630 Ma).				4600

Proposed Precambrian timeline [edit]

The ICS's Geologic Time Scale 2012 book which includes the new approved fourth dimension scale too displays a proposal to essentially revise the Precambrian fourth dimension scale to reflect important events such as the formation of the Earth or the Not bad Oxidation Event, among others, while at the same time maintaining near of the previous chronostratigraphic nomenclature for the pertinent time span.^[63] (Meet also Menstruum (geology)#Structure.)

• Hadean Eon – 4567–4030 Ma
  • Chaotian Era – 4567–4404 Ma – the name alluding both to the mythological Chaos and the chaotic phase of planet formation^{[63] [60] [64]}
  • Jack Hillsian or Zirconian Era – 4404–4030 Ma – both names allude to the Jack Hills Greenstone Belt which provided the oldest mineral grains on Earth, zircons^{[63] [threescore]}
• Archean Eon – 4030–2420 Ma
  • Paleoarchean Era – 4030–3490 Ma
    • Acastan Period – 4030–3810 Ma – named after the Acasta Gneiss^{[63] [60]}
    • Isuan Catamenia – 3810–3490 Ma – named after the Isua Greenstone Belt^[63]
  • Mesoarchean Era – 3490–2780 Ma
    • Vaalbaran Period – 3490–3020 Ma – based on the names of the Kapvaal (Southern Africa) and Pilbara (Western Australia) cratons^[63]
    • Pongolan Flow – 3020–2780 Ma – named later the Pongola Supergroup^[63]
  • Neoarchean Era – 2780–2420 Ma
    • Methanian Period – 2780–2630 Ma – named for the inferred predominance of methanotrophic prokaryotes^[63]
    • Siderian Period – 2630–2420 Ma – named for the voluminous banded iron formations formed inside its elapsing^[63]
• Proterozoic Eon – 2420–541 Ma
  • Paleoproterozoic Era – 2420–1780 Ma
    • Oxygenian Period – 2420–2250 Ma – named for displaying the start testify for a global oxidizing atmosphere^[63]
    • Jatulian or Eukaryian Period – 2250–2060 Ma – names are respectively for the Lomagundi–Jatuli δ¹³C isotopic circuit event spanning its duration, and for the (proposed)^{[65] [66]} first fossil advent of eukaryotes^[63]
    • Columbian Period – 2060–1780 Ma – named afterward the supercontinent Columbia^[63]
  • Mesoproterozoic Era – 1780–850 Ma
    • Rodinian Period – 1780–850 Ma – named after the supercontinent Rodinia, stable environment^[63]
  • Neoproterozoic Era – 850–541 Ma
    • Cryogenian Period – 850–630 Ma – named for the occurrence of several glaciations^[63]
    • Ediacaran Period – 630–541 Ma

Shown to scale:

Compare with the current official timeline, shown to scale:

See too [edit]

• Historic period of the World
• Bubnoff unit
• Catholic calendar
• Deep time
• Evolutionary history of life
• Geological history of Earth
• Geology of Mars/areology
• Geon
• Graphical timeline of the universe
• History of the Earth
• History of geology
• History of paleontology
• List of fossil sites
• List of geochronologic names
• Logarithmic timeline
• Lunar geologic timescale
• Martian geologic timescale
• Natural history
• New Zealand geologic time scale
• Prehistoric life
• Timeline of the Big Bang
• Timeline of evolution
• Timeline of the geologic history of the United States
• Timeline of human development
• Timeline of natural history
• Timeline of paleontology

Notes [edit]

1. ^ Not enough is known about extra-solar planets for worthwhile speculation.
2. ^ Paleontologists often refer to faunal stages rather than geologic (geological) periods. The phase nomenclature is quite complex. For a time-ordered list of faunal stages, see.^[44]
3. ^ ^{a b} Dates are slightly uncertain with differences of a few percentage betwixt various sources being common. This is largely due to uncertainties in radiometric dating and the problem that deposits suitable for radiometric dating seldom occur exactly at the places in the geologic column where they would be most useful. The dates and errors quoted above are according to the International Commission on Stratigraphy v2022/02 time scale except the Hadean eon. Where errors are non quoted, errors are less than the precision of the age given.

   * indicates boundaries where a Global Boundary Stratotype Section and Bespeak has been internationally agreed upon.

4. ^ References to the "Post-Cambrian Supereon" are not universally accustomed, and therefore must exist considered unofficial.
5. ^ Historically, the Cenozoic has been divided up into the Quaternary and Third sub-eras, as well as the Neogene and Paleogene periods. The 2009 version of the ICS time chart^[45] recognizes a slightly extended 4th as well every bit the Paleogene and a truncated Neogene, the Third having been demoted to breezy status.
6. ^ ^{a b c d} For more information on this, see Atmosphere of Earth#Evolution of Globe's atmosphere, Carbon dioxide in the Earth's atmosphere, and climate change. Specific graphs of reconstructed CO₂ levels over the by ~550, 65, and 5 meg years can be seen at File:Phanerozoic Carbon Dioxide.png, File:65 Myr Climate Change.png, File:Five Myr Climate change.png, respectively.
7. ^ In N America, the Carboniferous is subdivided into Mississippian and Pennsylvanian Periods.
8. ^ The Precambrian is likewise known every bit Cryptozoic.
9. ^ ^{a b c d e f m h i j chiliad l thou northward} The Proterozoic, Archean and Hadean are often collectively referred to as the Precambrian or, sometimes, the Cryptozoic.
10. ^ ^{a b c d due east f grand h i j k l} Divers by accented historic period (Global Standard Stratigraphic Historic period).
11. ^ The historic period of the oldest measurable craton, or continental crust, is dated to 3,600–iii,800 Ma.
12. ^ Though commonly used, the Hadean is not a formal eon^[58] and no lower leap for the Archean and Eoarchean have been agreed upon. The Hadean has also sometimes been chosen the Priscoan or the Azoic. Sometimes, the Hadean can be found to be subdivided according to the lunar geologic timescale. These eras include the Cryptic and Bowl Groups (which are subdivisions of the Pre-Nectarian era), Nectarian, and Early Imbrian units.
13. ^ ^{a b c d} These unit names were taken from the lunar geologic timescale and refer to geologic events that did not occur on Earth. Their apply for Globe geology is unofficial. Note that their start times do not dovetail perfectly with the later on, terrestrially defined boundaries.

References [edit]

1. ^ ^{a b c} Cohen, K.M.; Finney, S.C.; Gibbard, P.L.; Fan, J.-X. (1 September 2013). "The ICS International Chronostratigraphic Chart". Episodes (updated ed.). 36 (3): 199–204. doi:ten.18814/epiiugs/2013/v36i3/002. ISSN 0705-3797.
2. ^ ^{a b} "Chapter 9. Chronostratigraphic units". Stratigraphic guide. International Commission on Stratigraphy. Archived from the original on 28 December 2012. Retrieved ii Baronial 2018.
3. ^ A lexicon of geology and earth sciences. Michael Allaby (4th ed.). Oxford: Oxford University Press. 2013. ISBN978-0-nineteen-174433-four. OCLC 860061071. {{cite book}}: CS1 maint: others (link)
4. ^ Cohen, G.Chiliad.; Finney, S.; Gibbard, P.L. (2015), International Chronostratigraphic Chart (PDF), International Commission on Stratigraphy .
5. ^ Erwin D.H. (1994). "The Permo–Triassic Extinction" (PDF). Nature. 367 (6460): 231–236. Bibcode:1994Natur.367..231E. doi:10.1038/367231a0. S2CID 4328753. Archived from the original (PDF) on viii February 2018. Retrieved 4 September 2021.
6. ^ "The KT extinction". ucmp.berkeley.edu . Retrieved 8 Feb 2022.
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Further reading [edit]

• Aubry, Marie-Pierre; Van Couvering, John A.; Christie-Blick, Nicholas; Landing, Ed; Pratt, Brian R.; Owen, Donald E.; Ferrusquia-Villafranca, Ismael (2009). "Terminology of geological fourth dimension: Establishment of a customs standard". Stratigraphy. 6 (2): 100–105. doi:10.7916/D8DR35JQ.
• Gradstein, F. M.; Ogg, J. One thousand. (2004). "A Geologic Fourth dimension scale 2004 – Why, How and Where Next!" (PDF). Lethaia. 37 (2): 175–181. doi:10.1080/00241160410006483. Archived from the original (PDF) on 17 April 2018. Retrieved 30 Nov 2018.
• Gradstein, Felix M.; Ogg, James Chiliad.; Smith, Alan 1000. (2004). A Geologic Time Scale 2004. Cambridge, United kingdom of great britain and northern ireland: Cambridge University Press. ISBN978-0-521-78142-8 . Retrieved 18 Nov 2011.
• Gradstein, Felix Thousand.; Ogg, James G.; Smith, Alan G.; Bleeker, Wouter; Laurens, Lucas, J. (June 2004). "A new Geologic Fourth dimension Scale, with special reference to Precambrian and Neogene". Episodes. 27 (ii): 83–100. doi:10.18814/epiiugs/2004/v27i2/002.
• Ialenti, Vincent (28 September 2014). "Embracing 'Deep Fourth dimension' Thinking". NPR. NPR Cosmos & Civilisation.
• Ialenti, Vincent (21 September 2014). "Pondering 'Deep Time' Could Inspire New Ways To View Climate Change". NPR. NPR Creation & Civilization.
• Knoll, Andrew H.; Walter, Malcolm R.; Narbonne, Guy Thousand.; Christie-Blick, Nicholas (30 July 2004). "A New Period for the Geologic Time Scale" (PDF). Science. 305 (5684): 621–622. doi:10.1126/scientific discipline.1098803. PMID 15286353. S2CID 32763298. Retrieved 18 November 2011.
• Levin, Harold L. (2010). "Fourth dimension and Geology". The Globe Through Fourth dimension. Hoboken, New Jersey: John Wiley & Sons. ISBN978-0-470-38774-0 . Retrieved 18 November 2011.
• Montenari, Michael (2016). Stratigraphy and Timescales (1st ed.). Amsterdam: Bookish Press (Elsevier). ISBN978-0-12-811549-7.

External links [edit]

• International Chronostratigraphic Chart (interactive)
• International Chronostratigraphic Chart (v 2020/03)
• Global Purlieus Stratotype Section and Points
• NASA: Geologic Time
• GSA: Geologic Time Calibration
• British Geological Survey: Geological Timechart
• GeoWhen Database
• National Museum of Natural History – Geologic Time
• SeeGrid: Geological Time Systems Archived 23 July 2008 at the Wayback Machine Information model for the geologic time scale
• Exploring Time from Planck Fourth dimension to the lifespan of the universe
• Episodes, Gradstein, Felix G. et al. (2004) A new Geologic Time Scale, with special reference to Precambrian and Neogene, Episodes, Vol. 27, no. 2 June 2004 (pdf)
• Lane, Alfred C, and Marble, John Putman 1937. Report of the Committee on the measurement of geologic fourth dimension
• Lessons for Children on Geologic Fourth dimension
• Deep Time – A History of the Globe : Interactive Infographic
• Geology Fizz: Geologic Time Scale

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