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The geologic time scale or geological time scale ( GTS) is a representation of time based on the geologic record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating stratum to time) and geochronology (a scientific branch of geology that aims to determine the age of rocks). It is used primarily by Earth science (including , paleontology, geophysics, geochemistry, and paleoclimatology) to describe the timing and relationships of events in geologic history. The time scale has been developed through the study of rock layers and the observation of their relationships and identifying features such as lithology, paleomagnetism properties, and . The definition of standardised international units of geological time is the responsibility of the International Commission on Stratigraphy (ICS), a constituent body of the International Union of Geological Sciences (IUGS), whose primary objective is to precisely define global chronostratigraphic units of the International Chronostratigraphic Chart (ICC) that are used to define divisions of geological time. The chronostratigraphic divisions are in turn used to define geochronologic units.
Historically, regional geologic time scales were used due to the litho- and biostratigraphic differences around the world in time equivalent rocks. The ICS has long worked to reconcile conflicting terminology by standardising globally significant and identifiable stratigraphic horizons that can be used to define the lower boundaries of chronostratigraphic units. Defining chronostratigraphic units in such a manner allows for the use of global, standardised nomenclature. The International Chronostratigraphic Chart represents this ongoing effort.
Several key principles are used to determine the relative relationships of rocks and thus their chronostratigraphic position.
The law of superposition that states that in undeformed stratigraphic sequences the oldest strata will lie at the bottom of the sequence, while newer material stacks upon the surface. In practice, this means a younger rock will lie on top of an older rock unless there is evidence to suggest otherwise.
The principle of original horizontality that states layers of sediments will originally be deposited horizontally under the action of gravity. However, it is now known that not all sedimentary layers are deposited purely horizontally, but this principle is still a useful concept.
The principle of lateral continuity that states layers of sediments extend laterally in all directions until either thinning out or being cut off by a different rock layer, i.e. they are laterally continuous. Layers do not extend indefinitely; their limits are controlled by the amount and type of sediment in a sedimentary basin, and the geometry of that basin.
The principle of cross-cutting relationships that states a rock that cuts across another rock must be younger than the rock it cuts across.
The law of included fragments that states small fragments of one type of rock that are embedded in a second type of rock must have formed first, and were included when the second rock was forming.
The relationships of unconformity which are geologic features representing a gap in the geologic record. Unconformities are formed during periods of erosion or non-deposition, indicating non-continuous sediment deposition. Observing the type and relationships of unconformities in strata allows geologist to understand the relative timing of the strata.
The principle of faunal succession (where applicable) that states rock strata contain distinctive sets of fossils that succeed each other vertically in a specific and reliable order. This allows for a correlation of strata even when the horizon between them is not continuous.
| +Formal, hierarchical units of the geologic time scale (largest to smallest) !Chronostratigraphic unit (strata) !Geochronologic unit (time) !Time span | ||
| Eonothem | Eon | Several hundred million years to two billion years |
| Erathem | Era | Tens to hundreds of millions of years |
| System | Period | Millions of years to tens of millions of years |
| Series | Epoch | Hundreds of thousands of years to tens of millions of years |
| Subseries | Subepoch | Thousands of years to millions of years |
| Stage | Age | Thousands of years to millions of years |
The subdivisions and are used as the geochronologic equivalents of the chronostratigraphic and , e.g., Early Triassic Period (geochronologic unit) is used in place of Lower Triassic System (chronostratigraphic unit).
Rocks representing a given chronostratigraphic unit are that chronostratigraphic unit, and the time they were laid down in is the geochronologic unit, e.g., the rocks that represent the Silurian System the Silurian System and they were deposited the Silurian Period. This definition means the numeric age of a geochronologic unit can be changed (and is more often subject to change) when refined by geochronometry while the equivalent chronostratigraphic unit (the revision of which is less frequent) remains unchanged. For example, in early 2022, the boundary between the Ediacaran and Cambrian periods (geochronologic units) was revised from 541 Ma to 538.8 Ma but the rock definition of the boundary (GSSP) at the base of the Cambrian, and thus the boundary between the Ediacaran and Cambrian systems (chronostratigraphic units) has not been changed; rather, the absolute age has merely been refined.
is the element of [[stratigraphy]] that deals with the relation between rock bodies and the relative measurement of geological time. It is the process where distinct strata between defined stratigraphic horizons are assigned to represent a relative interval of geologic time.
A is a body of rock, layered or unlayered, that is defined between specified stratigraphic horizons which represent specified intervals of geologic time. They include all rocks representative of a specific interval of geologic time, and only this time span. Eonothem, erathem, system, series, subseries, stage, and substage are the hierarchical chronostratigraphic units.
A is a subdivision of geologic time. It is a numeric representation of an intangible property (time). These units are arranged in a hierarchy: eon, era, period, epoch, subepoch, age, and subage.
is the scientific branch of geology that aims to determine the age of rocks, fossils, and sediments either through absolute (e.g., radiometric dating) or relative means (e.g., stratigraphic position, [[paleomagnetism]], stable isotope ratios). is the field of geochronology that numerically quantifies geologic time.
A (GSSP) is an internationally agreed-upon reference point on a stratigraphic section that defines the lower boundaries of stages on the geologic time scale. (Recently this has been used to define the base of a system)
A (GSSA) is a numeric-only, chronologic reference point used to define the base of geochronologic units prior to the Cryogenian. These points are arbitrarily defined. They are used where GSSPs have not yet been established. Research is ongoing to define GSSPs for the base of all units that are currently defined by GSSAs.
The standard international units of the geologic time scale are published by the International Commission on Stratigraphy on the International Chronostratigraphic Chart; however, regional terms are still in use in some areas. The numeric values on the International Chronostratigrahpic Chart are represented by the unit Megaannum (megaannum, for 'million '). For example, Ma, the lower boundary of the Jurassic Period, is defined as 201,400,000 years old with an uncertainty of 200,000 years. Other Si prefix units commonly used by geologists are Gigaannum (gigaannum, billion years), and Kiloannums (kiloannum, thousand years), with the latter often represented in calibrated units (Before Present).
Informally, the time before the Cambrian is often referred to as the Precambrian or pre-Cambrian (Supereon).
| +Time span and etymology of geologic eonothem/eon names !Name !Time span !Duration (million years) !Etymology of name | |||
| Phanerozoic | From Greek φανερός ( phanerós) 'visible' or 'abundant' and ζωή ( zoē) 'life'. | ||
| Proterozoic | From Greek πρότερος ( próteros) 'former' or 'earlier' and ζωή ( zoē) 'life'. | ||
| Archean | From Greek ἀρχή ( archē) 'beginning, origin'. | ||
| Hadean | From Hades, , the god of the underworld (hell, the inferno) in Greek mythology. |
| +Time span and etymology of geologic erathem/era names !Name !Time span !Duration (million years) !Etymology of name | |||
| Cenozoic | From Greek καινός ( kainós) 'new' and ζωή ( zōḗ) 'life'. | ||
| Mesozoic | From Greek μέσο ( méso) 'middle' and ζωή ( zōḗ) 'life'. | ||
| Paleozoic | From Greek παλιός ( palaiós) 'old' and ζωή ( zōḗ) 'life'. | ||
| Neoproterozoic | From Greek νέος ( néos) 'new' or 'young', πρότερος ( próteros) 'former' or 'earlier', and ζωή ( zōḗ) 'life'. | ||
| Mesoproterozoic | From Greek μέσο ( méso) 'middle', πρότερος ( próteros) 'former' or 'earlier', and ζωή ( zōḗ) 'life'. | ||
| Paleoproterozoic | From Greek παλιός ( palaiós) 'old', πρότερος ( próteros) 'former' or 'earlier', and ζωή ( zōḗ) 'life'. | ||
| Neoarchean | From Greek νέος ( néos) 'new' or 'young' and ἀρχαῖος ( arkhaîos) 'ancient'. | ||
| Mesoarchean | From Greek μέσο ( méso) 'middle' and ἀρχαῖος ( arkhaîos) 'ancient'. | ||
| Paleoarchean | From Greek παλιός ( palaiós) 'old' and ἀρχαῖος ( arkhaîos) 'ancient'. | ||
| Eoarchean | From Greek ἠώς ( ēōs) 'dawn' and ἀρχαῖος ( arkhaîos) 'ancient'. |
| +Time span and etymology of geologic series/epoch names !Name !Time span !Duration (million years) !Etymology of name | |||
| Holocene | From Greek ὅλος ( hólos) 'whole' and καινός ( kainós) 'new' | ||
| Pleistocene | Coined in the early 1830s from Greek πλεῖστος ( pleîstos) 'most' and καινός ( kainós) 'new' | ||
| Pliocene | Coined in the early 1830s from Greek πλείων ( pleíōn) 'more' and καινός ( kainós) 'new' | ||
| Miocene | Coined in the early 1830s from Greek μείων ( meíōn) 'less' and καινός ( kainós) 'new' | ||
| Oligocene | Coined in the 1850s from Greek ὀλίγος ( olígos) 'few' and καινός ( kainós) 'new' | ||
| Eocene | Coined in the early 1830s from Greek ἠώς ( ēōs) 'dawn' and καινός ( kainós) 'new', referring to the dawn of modern life during this epoch | ||
| Paleocene | Coined by Wilhelm Philippe Schimper in 1874 as a portmanteau of paleo- + Eocene, but on the surface from Greek παλαιός ( palaios) 'old' and καινός ( kainós) 'new' | ||
| Upper Cretaceous | See Cretaceous | ||
| Lower Cretaceous | |||
| Upper Jurassic | See Jurassic | ||
| Middle Jurassic | |||
| Lower Jurassic | |||
| Upper Triassic | See Triassic | ||
| Middle Triassic | |||
| Lower Triassic | |||
| Lopingian | Named for Leping, China, an anglicization of Mandarin 乐平 ( lèpíng) 'peaceful music' | ||
| Guadalupian | Named for the Guadalupe Mountains of the American Southwest, ultimately from Arabic وَادِي ٱل ( wādī al) 'valley of the' and Latin lupus 'wolf' via Spanish | ||
| Cisuralian | From Latin cis- (before) + Russian Урал ( Ural), referring to the western slopes of the Ural Mountains | ||
| Upper Pennsylvanian | Named for the US state of Pennsylvania, from William Penn + Latin silvanus (forest) + -ia by analogy to Transylvania | ||
| Middle Pennsylvanian | |||
| Lower Pennsylvanian | |||
| Upper Mississippian | Named for the Mississippi River, from Ojibwe ᒥᐦᓯᓰᐱ ( misi-ziibi) 'great river' | ||
| Middle Mississippian | |||
| Lower Mississippian | |||
| Upper Devonian | See Devonian | ||
| Middle Devonian | |||
| Lower Devonian | |||
| Pridoli Epoch | Named for the Homolka a Přídolí nature reserve near Prague, Czechia | ||
| Ludlow Epoch | Named after Ludlow, England | ||
| Wenlock Epoch | Named for the Wenlock Edge in Shropshire, England | ||
| Llandovery Epoch | Named after Llandovery, Wales | ||
| Upper Ordovician | See Ordovician | ||
| Middle Ordovician | |||
| Lower Ordovician | |||
| Furongian | From Mandarin 芙蓉 ( fúróng) 'lotus', referring to the state symbol of Hunan | ||
| Miaolingian | Named for the mountains of Guizhou, Mandarin for 'sprouting peaks' | ||
| Cambrian Series 2 (informal) | See Cambrian | ||
| Terreneuvian | Named for Terre-Neuve, a French calque of Newfoundland |
These views of da Vinci remained unpublished, and thus lacked influence at the time; however, questions of fossils and their significance were pursued and, while views against Genesis were not readily accepted and dissent from Religion doctrine was in some places unwise, scholars such as Girolamo Fracastoro shared da Vinci's views, and found the attribution of fossils to the 'Deluge' absurd. Although many theories surrounding philosophy and concepts of rocks were developed in earlier years, "the first serious attempts to formulate a geological time scale that could be applied anywhere on Earth were made in the late 18th century." Later, in the 19th century, academics further developed theories on stratification. William Smith, often referred to as the "Father of Geology" developed theories through observations rather than drawing from the scholars that came before him. Smith's work was primarily based on his detailed study of rock layers and fossils during his time and he created "the first map to depict so many rock formations over such a large area”. After studying rock layers and the fossils they contained, Smith concluded that each layer of rock contained distinct material that could be used to identify and correlate rock layers across different regions of the world. Smith developed the concept of faunal succession or the idea that fossils can serve as a marker for the age of the strata they are found in and published his ideas in his 1816 book, "Strata identified by organized fossils."
Respectively, these are the principles of superposition, original horizontality, lateral continuity, and cross-cutting relationships. From this Steno reasoned that strata were laid down in succession and inferred relative time (in Steno's belief, time from Creation myth). While Steno's principles were simple and attracted much attention, applying them proved challenging. These basic principles, albeit with improved and more nuanced interpretations, still form the foundational principles of determining the correlation of strata relative to geologic time.
- When any given stratum was being formed, all the matter resting on it was fluid and, therefore, when the lowest stratum was being formed, none of the upper strata existed.
- ... strata which are either perpendicular to the horizon or inclined to it were at one time parallel to the horizon.
- When any given stratum was being formed, it was either encompassed at its edges by another solid substance or it covered the whole globe of the earth. Hence, it follows that wherever bared edges of strata are seen, either a continuation of the same strata must be looked for or another solid substance must be found that kept the material of the strata from being dispersed.
- If a body or discontinuity cuts across a stratum, it must have formed after that stratum.
Over the course of the 18th-century geologists realised that:
During the early 19th century William Smith, Georges Cuvier, Jean d'Omalius d'Halloy, and Alexandre Brongniart pioneered the systematic division of rocks by stratigraphy and fossil assemblages. These geologists began to use the local names given to rock units in a wider sense, correlating strata across national and continental boundaries based on their similarity to each other. Many of the names below erathem/era rank in use on the modern ICC/GTS were determined during the early to mid-19th century.
The discovery of radioactive decay by Henri Becquerel, Marie Curie, and Pierre Curie laid the ground work for radiometric dating, but the knowledge and tools required for accurate determination of radiometric ages would not be in place until the mid-1950s. Early attempts at determining ages of uranium minerals and rocks by Ernest Rutherford, Bertram Boltwood, Robert Strutt, and Arthur Holmes, would culminate in what are considered the first international geological time scales by Holmes in 1911 and 1913. The discovery of in 1913 by Frederick Soddy, and the developments in mass spectrometry pioneered by Francis William Aston, Arthur Jeffrey Dempster, and Alfred O. C. Nier during the early to mid-20th century would finally allow for the accurate determination of radiometric ages, with Holmes publishing several revisions to his geological time-scale with his final version in 1960.
Following on from Holmes, several A Geological Time Scale books were published in 1982, 1989, 2004, 2008, 2012, 2016, and 2020. However, since 2013, the ICS has taken responsibility for producing and distributing the ICC citing the commercial nature, independent creation, and lack of oversight by the ICS on the prior published GTS versions (GTS books prior to 2013) although these versions were published in close association with the ICS. Subsequent Geologic Time Scale books (2016 and 2020) are commercial publications with no oversight from the ICS, and do not entirely conform to the chart produced by the ICS. The ICS produced GTS charts are versioned (year/month) beginning at v2013/01. At least one new version is published each year incorporating any changes ratified by the ICS since the prior version.
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id:hadean value:rgb(0.717,0,0.494)
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id:white value:white
Period = from:-4600 till:-538.8
TimeAxis = orientation:horizontal
ScaleMajor = unit:year increment:500 start:-4500
ScaleMinor = unit:year increment:100 start:-4500
PlotData =
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bar:Eonothem/Eon
from: -2450 till: -538.8 text:Proterozoic color:proterozoic
from: -4000 till: -2450 text:Archean color:archean
from: start till: -4000 text:Hadean color:hadean
bar:Erathem/Era
from: -1000 till: -538.8 text:Neoproterozoic color:neoproterozoic
from: -1800 till: -1000 text:Mesoproterozoic color:mesoproterozoic
from: -2450 till: -1800 text:Paleoproterozoic color:paleoproterozoic
from: -3000 till: -2450 text:Neoarchean color:neoarchean
from: -3300 till: -3000 text:Mesoarchean color:mesoarchean
from: -4000 till: -3300 text:Paleoarchean color:paleoarchean
from: start till: -4000 color:white
bar:System/Period fontsize:7
from: -635 till: -538.8 text:Ed. color:ediacaran
from: -720 till: -635 text:Cr. color:cryogenian
from: -800 till: -720 text:Tonian color:tonian
from: -1000 till: -800 text:?kleisian color:kleisian
from: -1200 till: -1000 text:Stenian color:stenian
from: -1400 till: -1200 text:Ectasian color:ectasian
from: -1600 till: -1400 text:Calymmian color:calymmian
from: -1800 till: -1600 text:Statherian color:statherian
from: -2050 till: -1800 text:Orosirian color:orosirian
from: -2300 till: -2050 text:Rhyacian color:rhyacian
from: -2450 till: -2300 text:?Skourian color:skourian
from: -2700 till: -2450 text:Siderian color:neoarchean
from: -3000 till: -2700 text:?Kratian color:neoarchean
from: start till: -3000 color:white
ICC pre-Cambrian timeline (v2024/12, current ), shown to scale:
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id:tonian value:rgb(0.996,0.75,0.305)
id:mesoproterozoic value:rgb(0.996,0.705,0.384)
id:stenian value:rgb(0.996,0.85,0.604)
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id:rhyacian value:rgb(0.968,0.357,0.537)
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id:archean value:rgb(0.996,0.157,0.498)
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id:mesoarchean value:rgb(0.968,0.408,0.662)
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Period = from:-4567 till:-538.8
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bar:Eonothem/Eon
from: -2500 till: -538.8 text:Proterozoic color:proterozoic
from: -4031 till: -2500 text:Archean color:archean
from: start till: -4031 text:Hadean color:hadean
bar:Erathem/Era
from: -1000 till: -538.8 text:Neoproterozoic color:neoproterozoic
from: -1600 till: -1000 text:Mesoproterozoic color:mesoproterozoic
from: -2500 till: -1600 text:Paleoproterozoic color:paleoproterozoic
from: -2800 till: -2500 text:Neoarchean color:neoarchean
from: -3200 till: -2800 text:Mesoarchean color:mesoarchean
from: -3600 till: -3200 text:Paleoarchean color:paleoarchean
from: -4031 till: -3600 text:Eoarchean color:eoarchean
from: start till: -4031 color:white
bar:Sytem/Period fontsize:7
from: -635 till: -538.8 text:Ed. color:ediacaran
from: -720 till: -635 text:Cr. color:cryogenian
from: -1000 till: -720 text:Tonian color:tonian
from: -1200 till: -1000 text:Stenian color:stenian
from: -1400 till: -1200 text:Ectasian color:ectasian
from: -1600 till: -1400 text:Calymmian color:calymmian
from: -1800 till: -1600 text:Statherian color:statherian
from: -2050 till: -1800 text:Orosirian color:orosirian
from: -2300 till: -2050 text:Rhyacian color:rhyacian
from: -2500 till: -2300 text:Siderian color:siderian
from: start till: -2500 color:white
Proposed pre-Cambrian timeline (GTS2012), shown to scale:
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id:ediacaran value:rgb(0.996,0.85,0.415)
id:cryogenian value:rgb(0.996,0.8,0.36)
id:tonian value:rgb(0.996,0.75,0.305)
id:mesoproterozoic value:rgb(0.996,0.705,0.384)
id:rodinian value:rgb(0.996,0.75,0.478)
id:paleoproterozoic value:rgb(0.968,0.263,0.44)
id:columbian value:rgb(0.968,0.459,0.655)
id:eukaryian value:rgb(0.968,0.408,0.596)
id:oxygenian value:rgb(0.968,0.357,0.537)
id:archean value:rgb(0.996,0.157,0.498)
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id:siderian value:rgb(0.976,0.7,0.85)
id:methanian value:rgb(0.976,0.65,0.8)
id:mesoarchean value:rgb(0.968,0.408,0.662)
id:pongolan value:rgb(0.968,0.5,0.75)
id:vaalbaran value:rgb(0.968,0.45,0.7)
id:paleoarchean value:rgb(0.96,0.266,0.624)
id:isuan value:rgb(0.96,0.35,0.65)
id:acastan value:rgb(0.96,0.3,0.6)
id:hadean value:rgb(0.717,0,0.494)
id:zirconian value:rgb(0.902,0.114,0.549)
id:chaotian value:rgb(0.8,0.05,0.5)
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Period = from:-4567.3 till:-538.8
TimeAxis = orientation:horizontal
ScaleMajor = unit:year increment:500 start:-4500
ScaleMinor = unit:year increment:100 start:-4500
PlotData =
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bar:Eonothem/Eon
from: -2420 till: -541 text:Proterozoic color:proterozoic
from: -4030 till: -2420 text:Archean color:archean
from: -4567 till: -4030 text:Hadean color:hadean
from: start till: -4567 color:white
bar:Erathem/Era
from: -850 till: -541 text:Neoproterozoic color:neoproterozoic
from: -1780 till: -850 text:Mesoproterozoic color:mesoproterozoic
from: -2420 till: -1780 text:Paleoproterozoic color:paleoproterozoic
from: -2780 till: -2420 text:Neoarchean color:neoarchean
from: -3490 till: -2780 text:Mesoarchean color:mesoarchean
from: -4030 till: -3490 text:Paleoarchean color:paleoarchean
from: -4404 till: -4030 text:Zirconian color:zirconian
from: -4567 till: -4404 text:Chaotian color:chaotian
from: start till: -4567 color:white
bar:System/Period fontsize:7
from: -630 till: -541 text:Ediacaran color:ediacaran
from: -850 till: -630 text:Cryogenian color:cryogenian
from: -1780 till: -850 text:Rodinian color:rodinian
from: -2060 till: -1780 text:Columbian color:columbian
from: -2250 till: -2060 text:Eukaryian color:eukaryian
from: -2420 till: -2250 text:Oxygenian color:oxygenian
from: -2630 till: -2420 text:Siderian color:siderian
from: -2780 till: -2630 text:Methanian color:methanian
from: -3020 till: -2780 text:Pongolan color:pongolan
from: -3490 till: -3020 text:Vaalbaran color:vaalbaran
from: -3810 till: -3490 text:Isuan color:isuan
from: -4030 till: -3810 text:Acastan color:acastan
from: start till: -4030 color:white
ICC pre-Cambrian timeline (v2024/12, current ), shown to scale:
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id:neoproterozoic value:rgb(0.996,0.701,0.258)
id:ediacaran value:rgb(0.996,0.85,0.415)
id:cryogenian value:rgb(0.996,0.8,0.36)
id:tonian value:rgb(0.996,0.75,0.305)
id:mesoproterozoic value:rgb(0.996,0.705,0.384)
id:stenian value:rgb(0.996,0.85,0.604)
id:ectasian value:rgb(0.996,0.8,0.541)
id:calymmian value:rgb(0.996,0.75,0.478)
id:paleoproterozoic value:rgb(0.968,0.263,0.44)
id:statherian value:rgb(0.968,0.459,0.655)
id:orosirian value:rgb(0.968,0.408,0.596)
id:rhyacian value:rgb(0.968,0.357,0.537)
id:siderian value:rgb(0.968,0.306,0.478)
id:archean value:rgb(0.996,0.157,0.498)
id:neoarchean value:rgb(0.976,0.608,0.757)
id:mesoarchean value:rgb(0.968,0.408,0.662)
id:paleoarchean value:rgb(0.96,0.266,0.624)
id:eoarchean value:rgb(0.902,0.114,0.549)
id:hadean value:rgb(0.717,0,0.494)
id:black value:black
id:white value:white
Period = from:-4567.3 till:-538.8
TimeAxis = orientation:horizontal
ScaleMajor = unit:year increment:500 start:-4500
ScaleMinor = unit:year increment:100 start:-4500
PlotData =
align:center textcolor:black fontsize:8 mark:(line,black) width:25 shift:(0,-5)
bar:Eonothem/Eon
from: -2500 till: -538.8 text:Proterozoic color:proterozoic
from: -4031 till: -2500 text:Archean color:archean
from: start till: -4031 text:Hadean color:hadean
bar:Erathem/Era
from: -1000 till: -538.8 text:Neoproterozoic color:neoproterozoic
from: -1600 till: -1000 text:Mesoproterozoic color:mesoproterozoic
from: -2500 till: -1600 text:Paleoproterozoic color:paleoproterozoic
from: -2800 till: -2500 text:Neoarchean color:neoarchean
from: -3200 till: -2800 text:Mesoarchean color:mesoarchean
from: -3600 till: -3200 text:Paleoarchean color:paleoarchean
from: -4031 till: -3600 text:Eoarchean color:eoarchean
from: start till: -4031 color:white
bar:System/Period fontsize:7
from: -635 till: -538.8 text:Ediacaran color:ediacaran
from: -720 till: -635 text:Cryogenian color:cryogenian
from: -1000 till: -720 text:Tonian color:tonian
from: -1200 till: -1000 text:Stenian color:stenian
from: -1400 till: -1200 text:Ectasian color:ectasian
from: -1600 till: -1400 text:Calymmian color:calymmian
from: -1800 till: -1600 text:Statherian color:statherian
from: -2050 till: -1800 text:Orosirian color:orosirian
from: -2300 till: -2050 text:Rhyacian color:rhyacian
from: -2500 till: -2300 text:Siderian color:siderian
from: start till: -2500 color:white
While some regional terms are still in use, the table of geologic time conforms to the nomenclature, ages, and colour codes set forth by the International Commission on Stratigraphy in the official International Chronostratigraphic Chart. The International Commission on Stratigraphy also provide an online interactive version of this chart. The interactive version is based on a service delivering a machine-readable Resource Description Framework/Web Ontology Language representation of the time scale, which is available through the Commission for the Management and Application of Geoscience Information GeoSciML project as a service and at a SPARQL end-point.
| Phanerozoic | Cenozoic | Quaternary | Holocene | Meghalayan | 4.2-kiloyear event, Austronesian expansion, increasing industrial CO2. | * |
| Northgrippian | 8.2-kiloyear event, Holocene climatic optimum. Sea level flooding of Doggerland and Sundaland. Sahara becomes a desert. End of Stone Age and start of recorded history. Humans finally expand into the Arctic Archipelago and Greenland. | * | ||||
| Greenlandian | Climate stabilises. Current interglacial and Holocene extinction begins. Agriculture begins. Humans spread across the wet Sahara and Arabia, the Extreme North, and the Americas (mainland and the Caribbean). | * | ||||
| Pleistocene | Late Pleistocene ('Tarantian') | Eemian interglacial, last glacial period, ending with Younger Dryas. Toba eruption. Pleistocene megafauna (including the last terror birds) extinction. Humans expand into Near Oceania and the Americas. | ||||
| Chibanian | Mid-Pleistocene Transition occurs, high amplitude 100 ka glacial period. Rise of Homo sapiens. | * | ||||
| Calabrian | Further cooling of the climate. Giant terror birds go extinct. Spread of Homo erectus across Afro-Eurasia. | * | ||||
| Gelasian | Start of Quaternary glaciations and unstable climate. Rise of the Pleistocene megafauna and Homo habilis. | * | ||||
| Neogene | Pliocene | Piacenzian | Greenland ice sheet develops as the cold slowly intensifies towards the Pleistocene. Atmospheric and content reaches present-day levels while landmasses also reach their current locations (e.g. the Isthmus of Panama joins the North America and , while allowing a faunal interchange). The last non-marsupial metatherians go extinct. Australopithecus common in East Africa; Stone Age begins. | * | ||
| Zanclean | of the Mediterranean Basin. Cooling climate continues from the Miocene. First equines and Elephantimorpha. Ardipithecus in Africa. | * | ||||
| Miocene | Messinian | Messinian Event with hypersaline lakes in empty Mediterranean Basin. Sahara desert formation begins. Moderate icehouse climate, punctuated by and re-establishment of East Antarctic Ice Sheet. Choristodera, the last non-crocodilian Sebecosuchia and Creodonta go extinct. After separating from gorilla ancestors, chimpanzee and human ancestors gradually separate; Sahelanthropus and Orrorin in Africa. | * | |||
| Tortonian | * | |||||
| Serravallian | Middle Miocene climate optimum temporarily provides a warm climate. Extinctions in middle Miocene disruption, decreasing shark diversity. First . Ancestor of Hominidae. | * | ||||
| Langhian | * | |||||
| Burdigalian | Orogeny in Northern Hemisphere. Start of Kaikoura Orogeny forming Southern Alps in New Zealand. Widespread forests slowly Photosynthesis massive amounts of , gradually lowering the level of atmospheric from 650 ppmv down to around 100 ppmv during the Miocene. Modern bird and mammal families become recognizable. The last of the primitive whales go extinct. Poaceae become ubiquitous. Ancestor of , including humans. Afro-Arabia collides with Eurasia, fully forming the Alpide Belt and closing the Tethys Ocean, while allowing a faunal interchange. At the same time, Afro-Arabia splits into Africa and Arabian Plate. | |||||
| Aquitanian age | * | |||||
| Paleogene | Oligocene | Chattian | Grande Coupure extinction. Start of widespread Antarctic glaciation. Rapid evolution and diversification of fauna, especially (e.g. first Macropodiformes and Pinnipedia). Major evolution and dispersal of modern types of . , miacoids and condylarths go extinct. First Cetacea (modern, fully aquatic whales) appear. | * | ||
| Rupelian | * | |||||
| Eocene | Priabonian | Moderate, cooling climate. Archaic (e.g. , Miacoidea, "" etc.) flourish and continue to develop during the epoch. Appearance of several "modern" mammal families. Archaeoceti and Sirenia diversify after returning to water. continue to diversify. First kelp, Diprotodontia, and . The multituberculates and leptictidans go extinct by the end of the epoch. Reglaciation of Antarctica and formation of its ice cap; End of Laramide Orogeny and Sevier orogeny of the Rocky Mountains in North America. Hellenic orogeny begins in Greece and Aegean Sea. | * | |||
| Bartonian | ||||||
| Lutetian | * | |||||
| Ypresian | Two transient events of global warming (PETM and ETM-2) and warming climate until the Eocene Climatic Optimum. The Azolla event decreased levels from 3500 ppm to 650 ppm, setting the stage for a long period of cooling. Greater India 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 rest of Eurasia. First , , , and true . | * | ||||
| Paleocene | Thanetian | Starts with Chicxulub impact and the K–Pg extinction event, wiping out all non-avian dinosaurs and pterosaurs, most marine reptiles, many other vertebrates (e.g. many Laurasian metatherians), most cephalopods (only Nautilidae and Coleoidea survived) and many other invertebrates. Climate tropical. and (avians) diversify rapidly into a number of lineages following the extinction event (while the marine revolution stops). Multituberculates and the first widespread. First large birds (e.g. ratites and terror birds) and mammals (up to bear or small hippo size). Alpine orogeny in Europe and Asia begins. First and plesiadapiformes (stem primates) appear. Australidelphia migrate to Australia. | * | |||
| Selandian | * | |||||
| Danian | * | |||||
| Mesozoic | Cretaceous | Late Cretaceous | Maastrichtian | proliferate (after developing many features since the Carboniferous), along with new types of , while other seed plants (gymnosperms and seed ferns) decline. More modern teleost fish begin to appear. , Belemnoidea, rudist , and all common. Many new types of (e.g. Tyrannosauridae, Titanosauridae, Hadrosauridae, and Ceratopsidae) evolve on land, while appear in water and probably cause the last temnospondyls to die out; and and modern types of sharks appear in the sea. The revolution started by marine reptiles and sharks reaches its peak, though ichthyosaurs vanish a few million years after being heavily reduced at the Bonarelli Event. Toothed and Neornithes coexist with pterosaurs. Modern , (including , who migrate to South America) and (including , and ) mammals appear while the last non-mammalian cynodonts die out. First . Many snails become terrestrial. Further breakup of Gondwana creates South America, AfricaWest Asia, Antarctica, Oceania, Madagascar, Greater India, and the South Atlantic, Indian Ocean and and the islands of the Indian (and some of the Atlantic) Ocean. Beginning of Laramide Orogeny and Sevier Orogeny of the Rocky Mountains. Atmospheric oxygen and carbon dioxide levels similar to present day. disappear. Climate initially warm, but later it cools. | * | |
| Campanian | * | |||||
| Santonian | * | |||||
| Coniacian | * | |||||
| Turonian | * | |||||
| Cenomanian | * | |||||
| Early Cretaceous | Albian | ~ * | ||||
| Aptian | ~ | |||||
| Barremian | ~ * | |||||
| Hauterivian | ~ * | |||||
| Valanginian | ~ * | |||||
| Berriasian | ~ | |||||
| Jurassic | Late Jurassic | Tithonian | Climate becomes humid again. (especially , and ) and common. , including , , and , become the dominant land vertebrates. Mammals diversify into Shuotheriidae, , , , , and but mostly remain small. First Avialae, Squamata and . First brown algae, Batoidea, , and . ichthyosaurs and diverse. Rhynchocephalians throughout the world. , and Belemnoidea abundant. very common, along with , starfish, Porifera, and Terebratulida and Rhynchonellida . Breakup of Pangaea into Laurasia and Gondwana, with the latter also breaking into two main parts; the Pacific and form. Tethys Ocean forms. Nevadan orogeny in North America. Rangitata and Cimmerian orogenies taper off. Atmospheric levels 3–4 times the present-day levels (1200–1500 ppmv, compared to today's 400 ppmv). (last pseudosuchians) seek out an aquatic lifestyle. Mesozoic marine revolution continues from late Triassic. disappear. | |||
| Kimmeridgian | * | |||||
| Oxfordian stage | ||||||
| Middle Jurassic | Callovian | |||||
| Bathonian | * | |||||
| Bajocian | * | |||||
| Aalenian | * | |||||
| Early Jurassic | Toarcian | * | ||||
| Pliensbachian | * | |||||
| Sinemurian | * | |||||
| Hettangian | * | |||||
| Triassic | Late Triassic | Rhaetian | dominant on land as and in the air as . also arise from bipedal archosaurs. Ichthyosauria and (a group of sauropterygians) dominate large marine fauna. become smaller and nocturnal, eventually becoming the first true mammals, while other remaining synapsids die out. (archosaur relatives) also common. Seed ferns called Dicroidium remained common in Gondwana, before being replaced by advanced gymnosperms. Many large aquatic Temnospondyli amphibians. ammonoids extremely common. Scleractinia and teleost fish appear, as do many modern insect orders and suborders. First starfish. Andes Mountains in South America. Cimmerian Orogeny in Asia. Rangitata Orogeny begins in New Zealand. Hunter-Bowen Orogeny in Northern Australia, Queensland and New South Wales ends, (c. 260–225 Ma). Carnian pluvial event occurs around 234–232 Ma, allowing the first dinosaurs and lepidosaurs (including ) to radiate. Triassic–Jurassic extinction event occurs 201 Ma, wiping out all conodonts and the Procolophonidae, many marine reptiles (e.g. all sauropterygians except plesiosaurs and all ichthyosaurs except ), all except crocodylomorphs, pterosaurs, and dinosaurs, and many ammonoids (including the whole Ceratitida), bivalves, brachiopods, corals and sponges. First diatoms. | ~ | ||
| Norian | ~ | |||||
| Carnian | ~ * | |||||
| Middle Triassic | Ladinian | ~ * | ||||
| Anisian | ||||||
| Early Triassic | Olenekian | |||||
| Induan | * | |||||
| Paleozoic | Permian | Lopingian | Changhsingian | unite into supercontinent Pangaea, creating the Urals, Ouachitas and Appalachians, among other mountain ranges (the superocean Panthalassa or Proto-Pacific also forms). End of Permo-Carboniferous glaciation. Hot and dry climate. A possible drop in oxygen levels. Synapsida ( and ) become widespread and dominant, while and Temnospondyli remain common, with the latter probably giving rise to Lissamphibia in this period. In the mid-Permian, lycophytes are heavily replaced by ferns and seed plants. Beetles and Fly evolve. The very large arthropods and non-tetrapod tetrapodomorphs go extinct. Marine life flourishes in warm shallow reefs; Productida and Spiriferida brachiopods, bivalves, , ammonoids (including goniatites), and all abundant. Sauria arise from earlier diapsids, and split into the ancestors of lepidosaurs, Kuehneosauridae, Choristodera, Crocopoda, , ichthyosaurs, thalattosaurs, and . Cynodonts evolve from larger therapsids. Olson's Extinction (273 Ma), End-Capitanian extinction (260 Ma), and Permian–Triassic extinction event (252 Ma) occur one after another: more than 80% of life on Earth becomes extinct in the lattermost, including most plankton, corals (Tabulata and Rugosa die out fully), brachiopods, bryozoans, gastropods, ammonoids (the goniatites die off fully), insects, parareptiles, synapsids, amphibians, and crinoids (only articulates survived), and all , , , hyoliths, Edrioasteroidea, and acanthodians. Ouachita Orogeny and Innuitian orogenies in North America. Uralian orogeny in Europe/Asia tapers off. Altai Mountains orogeny in Asia. Hunter-Bowen Orogeny on Australian continent begins (c. 260–225 Ma), forming the New England Fold Belt. | * | |
| Wuchiapingian | * | |||||
| Guadalupian | Capitanian | * | ||||
| Wordian | * | |||||
| Roadian | * | |||||
| Cisuralian | Kungurian | |||||
| Artinskian | * | |||||
| Sakmarian | * | |||||
| Asselian | * | |||||
| Carboniferous | Pennsylvanian | Gzhelian | Pterygota radiate suddenly; some (esp. Protodonata and Palaeodictyoptera) of them as well as some and become very large. First coal forests (Lepidodendron, ferns, Sigillaria, Calamites, Cordaites, etc.). Higher atmospheric oxygen levels. Ice Age continues to the Early Permian. , brachiopods, bryozoa, bivalves, and corals plentiful in the seas and oceans. First woodlice. Testate 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). (e.g. temnospondyls) spread in Euramerica, with some becoming the first . Carboniferous Rainforest Collapse occurs, initiating a dry climate which favors amniotes over amphibians. Amniotes diversify rapidly into synapsids, parareptiles, Captorhinidae, protorothyridids and diapsids. remained common before they died out by the end of the period. First sharks. | |||
| Kasimovian | ||||||
| Moscovian | ||||||
| Bashkirian | * | |||||
| Mississippian | Serpukhovian | Large Lycopodiophyta flourish and amphibious live amid coal-forming coastal Brackish water, radiating significantly one last time. First gymnosperms. First Holometabola, , , and insects and first barnacles. First five-digited tetrapods (amphibians) and land snails. In the oceans, Bony fish and Chondrichthyes are dominant and diverse; (especially and ) abundant. , , , and brachiopods (Productida, Spiriferida, etc.) recover and become very common again, but Trilobita and decline. Glaciation in East Gondwana continues from Late Devonian. Tuhua Orogeny in New Zealand tapers off. Some lobe finned fish called rhizodonts become abundant and dominant in freshwaters. Siberia collides with a different small continent, Kazakhstania. | ||||
| Viséan | * | |||||
| Tournaisian | * | |||||
| Devonian | Late Devonian | Famennian | First Lycopodiopsida, ferns, seed plants (seed ferns, from earlier ), first trees (the progymnosperm Archaeopteris), and first Pterygota (palaeoptera and neoptera). Strophomenida and Atrypa , Rugosa and Tabulata corals, and are all abundant in the oceans. First fully coiled cephalopods (Ammonoidea and Nautilida, independently) with the former group very abundant (especially ). Trilobites and ostracoderms decline, while jawed fishes (Placodermi, Sarcopterygii and Actinopterygii Osteichthyes, and acanthodians and early Chondrichthyes) proliferate. Some Tetrapodomorpha transform into digited Stegocephalia, slowly becoming amphibious. The last non-trilobite artiopods die off. First decapods (like prawns) and isopods. Pressure from jawed fishes cause eurypterids to decline and Coleoidea to lose their shells while anomalocarids vanish. "Old Red Continent" of Euramerica persists after forming in the Caledonian orogeny. Beginning of Acadian Orogeny for Atlas Mountains of North Africa, and Appalachian Mountains of North America, also the Antler Orogeny, Variscan Orogeny, and Tuhua orogenies in New Zealand. A series of extinction events, including the massive Kellwasser event and Hangenberg event ones, wipe out many acritarchs, corals, sponges, molluscs, trilobites, eurypterids, graptolites, brachiopods, crinozoans (e.g. all cystoids), and fish, including all placoderms and ostracoderms. | * | ||
| Frasnian | * | |||||
| Middle Devonian | Givetian | * | ||||
| Eifelian | * | |||||
| Early Devonian | Emsian | * | ||||
| Pragian | * | |||||
| Lochkovian | * | |||||
| Silurian | Pridoli epoch | Ozone layer thickens. First and fully terrestrialised arthropods: myriapods, Hexapoda (including insects), and arachnids. diversify rapidly, becoming widespread and dominant. Cephalopods continue to flourish. True , along with , also roam the seas. Tabulate coral and Rugosa corals, ( Pentamerida, Rhynchonellida, etc.), cystoids and all abundant. and diverse; not as varied. Three minor extinction events. Some echinoderms go extinct. Beginning of Caledonian Orogeny (collision between Laurentia, Baltica and one of the formerly small Gondwanan terranes) for hills in England, Ireland, Wales, Scotland, and the Scandinavian Mountains. Also continued into Devonian period as the Acadian Orogeny, above (thus Euramerica forms). Taconic Orogeny tapers off. Icehouse period ends late in this period after starting in Late Ordovician. Lachlan Orogeny on Australian continent tapers off. | * | |||
| Ludlow epoch | Ludfordian | * | ||||
| Gorstian | * | |||||
| Wenlock epoch | Homerian | * | ||||
| Sheinwoodian | * | |||||
| Llandovery epoch | Telychian | * | ||||
| Aeronian | * | |||||
| Rhuddanian | * | |||||
| Ordovician | Late Ordovician | Hirnantian | The Great Ordovician Biodiversification Event occurs as plankton increase in number: diversify into many new types (especially brachiopods and molluscs; e.g. long Orthoconic cephalopods like the long lasting and diverse Orthocerida). Early , articulate ( Orthida, Strophomenida, etc.), bivalves, (nautiloids), , , , many types of echinoderms (blastoids, cystoids, crinoids, sea urchins, sea cucumbers, and Asterozoa, etc.), branched , and other taxa all common. still persist and common. Cephalopods become dominant and common, with some trending toward a coiled shell. Anomalocarids decline. Mysterious appear. First 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 terrestrialised Embryophyte. Ice age at the end of this period, as well as a series of mass extinction events, killing off some cephalopods and many brachiopods, bryozoans, echinoderms, graptolites, trilobites, bivalves, corals and conodonts. | * | ||
| Katian | * | |||||
| Sandbian | * | |||||
| Middle | Darriwilian | * | ||||
| Dapingian | * | |||||
| Early Ordovician | Floian (formerly Arenig) | * | ||||
| Tremadocian | * | |||||
| Cambrian | Furongian | Stage 10 | Major diversification of (fossils mainly show bilaterian) life in the Cambrian Explosion as oxygen levels increase. Numerous fossils; most modern animal phylum (including arthropods, Mollusca, , , and ) appear. Reef-building sponges initially abundant, then 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). First artiopods (including ), priapulid worms, inarticulate (unhinged lampshells), hyoliths, , , pentaradial echinoderms (e.g. , and ), and numerous other animals. are dominant and giant predators, while many Ediacaran fauna die out. and molluscs diversify rapidly. , (e.g., ), algae and fungi continue to present day. First from earlier chordates. Petermann Orogeny on the Australian continent tapers off (550–535 Ma). Ross Orogeny in Antarctica. Delamerian Orogeny (c. 514–490 Ma) on Australian continent. Some small terranes split off from Gondwana. Atmospheric content roughly 15 times present-day (Holocene) levels (6000 ppm compared to today's 400 ppm) and Embryophyte start colonising land. 3 extinction events occur 517, 502 and 488 Ma, the first and last of which wipe out many of the anomalocarids, artiopods, hyoliths, brachiopods, molluscs, and conodonts (early jawless vertebrates). | ~ | ||
| Jiangshanian | ~ * | |||||
| Paibian | ~ * | |||||
| Miaolingian | Guzhangian | ~ * | ||||
| Drumian | ~ * | |||||
| Wuliuan | ~ | |||||
| Series 2 | Stage 4 | ~ | ||||
| Stage 3 | ~ | |||||
| Terreneuvian | Stage 2 | ~ | ||||
| Fortunian | * | |||||
| Proterozoic | Neoproterozoic | Ediacaran | Good of primitive . Ediacaran biota flourish worldwide in seas, possibly appearing after an Avalon explosion, possibly caused by a large-scale oxidation event. First (unknown affinity among animals), and . Enigmatic vendozoans include many soft-jellied creatures shaped like bags, disks, or quilts (like Dickinsonia). Simple of possible worm-like Trichophycus, etc. Taconic Orogeny in North America. Aravalli Range orogeny in Indian subcontinent. Beginning of Pan-African Orogeny, leading to the formation of the short-lived Ediacaran supercontinent Pannotia, which by the end of the period breaks up 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. | ~ * | ||
| Cryogenian | Possible "Snowball Earth" period. still rare. Late Ruker / Nimrod Orogeny in Antarctica tapers off. First uncontroversial Sponge fossils. First hypothetical Amastigomycota and streptophyta. | ~ | ||||
| Tonian | Final assembly of Rodinia supercontinent occurs in early Tonian, with breakup beginning c. 800 Ma. Sveconorwegian orogeny ends. Grenville Orogeny tapers off in 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. First hypothetical animals (from holozoans) and terrestrial algal mats. Many endosymbiotic events concerning red and green algae occur, transferring plastids to ochrophyta (e.g. diatoms, brown algae), , cryptophyta, haptophyta, and (the events may have begun in the Mesoproterozoic) while the first (e.g. forams) also appear: eukaryotes diversify rapidly, including algal, eukaryovoric and biomineralised forms. of simple Multicellular eukaryotes. Neoproterozoic oxygenation event (NOE), 850–540 Ma. | |||||
| Mesoproterozoic | Stenian | Narrow highly Metamorphic rock belts due to orogeny as Rodinia forms, surrounded by the Pan-African Ocean. Sveconorwegian orogeny starts. Late Ruker / Nimrod Orogeny in Antarctica possibly begins. Musgrave Orogeny (c. 1,080–), Musgrave Block, Central Australia. decline as algae proliferate. | ||||
| Ectasian | continue to expand. colonies in the seas. Grenville Orogeny in North America. Columbia breaks up. | |||||
| Calymmian | expand. Barramundi Orogeny, McArthur Basin, Northern Australia, and Isan Orogeny, 1,600 Ma, Mount Isa Block, Queensland. First (the first eukaryotes with plastids from cyanobacteria; e.g. Red algae and green algae) and opisthokonts (giving rise to the first fungi and ). (remains of marine algae possibly) start appearing in the fossil record. | |||||
| Paleoproterozoic | Statherian | First uncontroversial eukaryotes: with nuclei and endomembrane system. Columbia forms as the second undisputed earliest supercontinent. Kimban Orogeny in Australian continent ends. Yapungku Orogeny on Yilgarn craton, in Western Australia. Mangaroon Orogeny, 1,680–1,620 Ma, on the Gascoyne Complex in Western Australia. Kararan Orogeny (1,650 Ma), Gawler craton, South Australia. Oxygen levels drop again. | ||||
| Orosirian | The atmosphere becomes much more while more cyanobacterial stromatolites appear. Vredefort and Sudbury Basin asteroid impacts. Much orogeny. Penokean orogeny and Trans-Hudsonian Orogenies in North America. Early Ruker Orogeny in Antarctica, 2,000–1,700 Ma. Glenburgh Orogeny, Gascoyne Complex, Australian continent 2,005–1,920 Ma. Kimban Orogeny, Gawler craton in Australian continent begins. | |||||
| Rhyacian | Bushveld Igneous Complex forms. Huronian glaciation. First hypothetical . Multicellular Francevillian biota. Kenorland disassembles. | |||||
| Siderian | Great Oxidation Event (due to cyanobacteria) increases oxygen. Sleaford Orogeny on Australian continent, Gawler craton 2,440–2,420 Ma. | |||||
| Archean | Neoarchean | Stabilization of most modern ; possible mantle overturn event. Insell Orogeny, 2,650 ± 150 Ma. Abitibi greenstone belt in present-day Ontario and Quebec begins to form, stabilises by 2,600 Ma. First uncontroversial supercontinent, Kenorland, and first terrestrial prokaryotes. | ||||
| Mesoarchean | (probably colonial phototrophic bacteria, like cyanobacteria). Oldest . Humboldt Orogeny in Antarctica. Blake River Megacaldera Complex begins to form in present-day Ontario and Quebec, ends by roughly 2,696 Ma. | |||||
| Paleoarchean | Prokaryotic archaea (e.g. methanogens) and bacteria (e.g. cyanobacteria) diversify rapidly, along with early viruses. First known bacteria. Oldest definitive microfossils. First microbial mats, stromatolites and MISS. Oldest on Earth (such as the Canadian Shield and the Pilbara craton) may have formed during this period. Rayner Orogeny in Antarctica. | |||||
| Eoarchean | First uncontroversial Life: at first with RNA world around 4000 Ma, after which true cells () evolve along with proteins and DNA-based genes around 3800 Ma. The end of the Late Heavy Bombardment. Napier Mountains Orogeny in Antarctica, 4,000 ± 200 Ma. | |||||
| Hadean | Formation of protolith of the oldest known rock (Acasta Gneiss) c. 4,031 to 3,580 Ma. Possible first appearance of . First hypothetical Abiogenesis. End of the Early Bombardment Phase. Oldest known mineral (Zircon, 4,404 ± 8 Ma). Asteroids and comets bring water to Earth, forming the first oceans. Formation of Moon (4,510 Ma), probably from a giant impact. Formation of Earth (4,543 to 4,540 Ma) | |||||
A second time scale based on mineral alteration observed by the OMEGA spectrometer on board the Mars Express. Using this method, three periods were defined, the Phyllocian (~4,500–4,000 Ma), Theiikian (~4,000–3,500 Ma), and Siderikian (~3,500 Ma to present).
Period = from:-4500 till:0
TimeAxis = orientation:horizontal
ScaleMajor = unit:year increment:500 start:-4500
ScaleMinor = unit:year increment:100 start:-4500
Colors =
PlotData=
id:sidericol value:rgb(1,0.4,0.3)
id:theiicol value:rgb(1,0.2,0.5)
id:phyllocol value:rgb(0.7,0.4,1)
align:center textcolor:black fontsize:8 mark:(line,black) width:25 shift:(0,-5)
text:Siderikan from:-3500 till:0 color:sidericol
text:Theiikian from:-4000 till:-3500 color:theiicol
text:Phyllocian from:start till:-4000 color:phyllocol
target="_blank" rel="nofollow"> GSA: Geologic Time Scale (archived 20 January 2019)
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