Geologic time scale

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The geologic time scale (GTS) is a system of chronological dating that classifies geological strata (stratigraphy) in time. Geologic time scale_sentence_0

It is used by geologists, paleontologists, and other Earth scientists to describe the timing and relationships of events in geologic history. Geologic time scale_sentence_1

The time scale was developed through the study of physical rock layers and relationships as well as the times when different organisms appeared, evolved and became extinct through the study of fossilized remains and imprints. Geologic time scale_sentence_2

The table of geologic time spans, presented here, agrees with the nomenclature, dates and standard color codes set forth by the International Commission on Stratigraphy (ICS). Geologic time scale_sentence_3

Terminology Geologic time scale_section_0

The primary and largest catalogued divisions of time are periods called eons. Geologic time scale_sentence_4

The first eon was the Hadean, when the Earth and moon were predicted to be formed, lasting over 600 million years until the Archean, which is when the Earth had cooled enough for continents and the earliest known life to emerge. Geologic time scale_sentence_5

After about 2.5 billion years, oxygen generated by photosynthesizing single-celled organisms began to appear in the atmosphere marking the beginning of the Proterozoic. Geologic time scale_sentence_6

Finally, the Phanerozoic eon encompasses 541 million years of diverse abundance of multicellular life starting with the appearance of hard animal shells in the fossil record and continuing to the present. Geologic time scale_sentence_7

Eons are divided into eras, which are in turn divided into periods, epochs and ages. Geologic time scale_sentence_8

The first three eons (i.e. every eon but the Phanerozoic) can be referred to collectively as the Precambrian supereon. Geologic time scale_sentence_9

This is in reference to the significance of the Cambrian Explosion, a massive diversification of multi-cellular life forms that took place in the Cambrian period at the start of the Phanerozoic. Geologic time scale_sentence_10

The following four timelines show the geologic time scale. Geologic time scale_sentence_11

The first shows the entire time from the formation of the Earth to the present, but this gives little space for the most recent eon. Geologic time scale_sentence_12

Therefore, the second timeline shows an expanded view of the most recent eon. Geologic time scale_sentence_13

In a similar way, the most recent era is expanded in the third timeline, and the most recent period is expanded in the fourth timeline. Geologic time scale_sentence_14

Corresponding to eons, eras, periods, epochs and ages, the terms "eonothem", "erathem", "system", "series", "stage" are used to refer to the layers of rock that belong to these stretches of geologic time in Earth's history. Geologic time scale_sentence_15

Geologists qualify these units as "early", "mid", and "late" when referring to time, and "lower", "middle", and "upper" when referring to the corresponding rocks. Geologic time scale_sentence_16

For example, the Lower Jurassic Series in chronostratigraphy corresponds to the Early Jurassic Epoch in geochronology. Geologic time scale_sentence_17

The adjectives are capitalized when the subdivision is formally recognized, and lower case when not; thus "early Miocene" but "Early Jurassic." Geologic time scale_sentence_18

Principles Geologic time scale_section_1

Evidence from radiometric dating indicates that Earth is about 4.54 billion years old. Geologic time scale_sentence_19

The geology or deep time of Earth's past has been organized into various units according to events which are thought to have taken place. Geologic time scale_sentence_20

Different spans of time on the GTS are usually marked by corresponding changes in the composition of strata which indicate major geological or paleontological events, such as mass extinctions. Geologic time scale_sentence_21

For example, the boundary between the Cretaceous period and the Paleogene period is defined by the Cretaceous–Paleogene extinction event, which marked the demise of the non-avian dinosaurs and many other groups of life. Geologic time scale_sentence_22

Older time spans, which predate the reliable fossil record (before the Proterozoic eon), are defined by their absolute age. Geologic time scale_sentence_23

Geologic units from the same time but different parts of the world often are not similar and contain different fossils, so the same time-span was historically given different names in different locales. Geologic time scale_sentence_24

For example, in North America, the Lower Cambrian is called the Waucoban series that is then subdivided into zones based on succession of trilobites. Geologic time scale_sentence_25

In East Asia and Siberia, the same unit is split into Alexian, Atdabanian, and Botomian stages. Geologic time scale_sentence_26

A key aspect of the work of the International Commission on Stratigraphy is to reconcile this conflicting terminology and define universal horizons that can be used around the world. Geologic time scale_sentence_27

Some other 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. Geologic time scale_sentence_28

Dominantly fluid planets, such as the gas giants, do not preserve their history in a comparable manner. Geologic time scale_sentence_29

Apart from the Late Heavy Bombardment, events on other planets probably had little direct influence on the Earth, and events on Earth had correspondingly little effect on those planets. Geologic time scale_sentence_30

Construction of a time scale that links the planets is, therefore, of only limited relevance to the Earth's time scale, except in a Solar System context. Geologic time scale_sentence_31

The existence, timing, and terrestrial effects of the Late Heavy Bombardment are still a matter of debate. Geologic time scale_sentence_32

History and nomenclature of the time scale Geologic time scale_section_2

Main articles: History of geology and History of paleontology Geologic time scale_sentence_33

Early history Geologic time scale_section_3

In Ancient Greece, Aristotle (384–322 BCE) observed that fossils of seashells in rocks resembled those found on beaches – he inferred that the fossils in rocks were formed by organisms, and he reasoned that the positions of land and sea had changed over long periods of time. Geologic time scale_sentence_34

Leonardo da Vinci (1452–1519) concurred with Aristotle's interpretation that fossils represented the remains of ancient life. Geologic time scale_sentence_35

The 11th-century Persian polymath Avicenna (Ibn Sina, died 1037) and the 13th-century Dominican bishop Albertus Magnus (died 1280) extended Aristotle's explanation into a theory of a petrifying fluid. Geologic time scale_sentence_36

Avicenna also first proposed one of the principles underlying geologic time scales, the law of superposition of strata, while discussing the origins of mountains in The Book of Healing (1027). Geologic time scale_sentence_37

The Chinese naturalist Shen Kuo (1031–1095) also recognized the concept of "deep time". Geologic time scale_sentence_38

Establishment of primary principles Geologic time scale_section_4

In the late 17th century Nicholas Steno (1638–1686) pronounced the principles underlying geologic (geological) time scales. Geologic time scale_sentence_39

Steno argued that rock layers (or strata) were laid down in succession, and that each represents a "slice" of time. Geologic time scale_sentence_40

He also formulated the law of superposition, which states that any given stratum is probably older than those above it and younger than those below it. Geologic time scale_sentence_41

While Steno's principles were simple, applying them proved challenging. Geologic time scale_sentence_42

Steno's ideas also lead to other important concepts geologists use today, such as relative dating. Geologic time scale_sentence_43

Over the course of the 18th century geologists realized that: Geologic time scale_sentence_44

Geologic time scale_ordered_list_0

  1. Sequences of strata often become eroded, distorted, tilted, or even inverted after depositionGeologic time scale_item_0_0
  2. Strata laid down at the same time in different areas could have entirely different appearancesGeologic time scale_item_0_1
  3. The strata of any given area represented only part of Earth's long historyGeologic time scale_item_0_2

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. Geologic time scale_sentence_45

A major shift in thinking came when James Hutton presented his Theory of the Earth; or, an Investigation of the Laws Observable in the Composition, Dissolution, and Restoration of Land Upon the Globe before the Royal Society of Edinburgh in March and April 1785. Geologic time scale_sentence_46

John McPhee asserts that "as things appear from the perspective of the 20th century, James Hutton in those readings became the founder of modern geology". Geologic time scale_sentence_47

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 then consolidated the sediment into stone, and uplifted it into new lands. Geologic time scale_sentence_48

This theory, known as "Plutonism", stood in contrast to the "Neptunist" flood-oriented theory. Geologic time scale_sentence_49

Formulation of geologic time scale Geologic time scale_section_5

The first serious attempts to formulate a geologic time scale that could be applied anywhere on Earth were made in the late 18th century. Geologic time scale_sentence_50

The most influential of those early attempts (championed by Werner, among others) divided the rocks of Earth's crust into four types: Primary, Secondary, Tertiary, and Quaternary. Geologic time scale_sentence_51

Each type of rock, according to the theory, formed during a specific period in Earth history. Geologic time scale_sentence_52

It was thus possible to speak of a "Tertiary Period" as well as of "Tertiary Rocks." Geologic time scale_sentence_53

Indeed, "Tertiary" (now Paleogene and Neogene) remained in use as the name of a geological period well into the 20th century and "Quaternary" remains in formal use as the name of the current period. Geologic time scale_sentence_54

The identification of strata by the fossils they contained, 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. Geologic time scale_sentence_55

It also enabled them to correlate strata across national (or even continental) boundaries. Geologic time scale_sentence_56

If two strata (however distant in space or different in composition) contained the same fossils, chances were good that they had been laid down at the same time. Geologic time scale_sentence_57

Detailed studies between 1820 and 1850 of the strata and fossils of Europe produced the sequence of geologic periods still used today. Geologic time scale_sentence_58

Naming of geologic periods, eras and epochs Geologic time scale_section_6

Early work on developing the geologic time scale was dominated by British geologists, and the names of the geologic periods reflect that dominance. Geologic time scale_sentence_59

The "Cambrian", (the classical name for Wales) and the "Ordovician" and "Silurian", named after ancient Welsh tribes, were periods defined using stratigraphic sequences from Wales. Geologic time scale_sentence_60

The "Devonian" was named for the English county of Devon, and the name "Carboniferous" was an adaptation of "the Coal Measures", the old British geologists' term for the same set of strata. Geologic time scale_sentence_61

The "Permian" was named after the region of Perm in Russia, because it was defined using strata in that region by Scottish geologist Roderick Murchison. Geologic time scale_sentence_62

However, some periods were defined by geologists from other countries. Geologic time scale_sentence_63

The "Triassic" was named in 1834 by a German geologist Friedrich Von Alberti from the three distinct layers (Latin trias meaning triad) – red beds, capped by chalk, followed by black shales – that are found throughout Germany and Northwest Europe, called the ‘Trias’. Geologic time scale_sentence_64

The "Jurassic" was named by a French geologist Alexandre Brongniart for the extensive marine limestone exposures of the Jura Mountains. Geologic time scale_sentence_65

The "Cretaceous" (from Latin creta meaning ‘chalk’) as a separate period was first defined by Belgian geologist Jean d'Omalius d'Halloy in 1822, using strata in the Paris basin and named for the extensive beds of chalk (calcium carbonate deposited by the shells of marine invertebrates) found in Western Europe. Geologic time scale_sentence_66

British geologists were also responsible for the grouping of periods into eras and the subdivision of the Tertiary and Quaternary periods into epochs. Geologic time scale_sentence_67

In 1841 John Phillips published the first global geologic time scale based on the types of fossils found in each era. Geologic time scale_sentence_68

Phillips' scale helped standardize the use of terms like Paleozoic ("old life") which he extended to cover a larger period than it had in previous usage, and Mesozoic ("middle life") which he invented. Geologic time scale_sentence_69

Dating of time scales Geologic time scale_section_7

Main article: Chronological dating Geologic time scale_sentence_70

When William Smith and Sir Charles Lyell first recognized that rock strata represented successive time periods, time scales could be estimated only very imprecisely since estimates of rates of change were uncertain. Geologic time scale_sentence_71

While creationists had been proposing dates of around six or seven thousand 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. Geologic time scale_sentence_72

Geologists and paleontologists constructed the geologic table 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. Geologic time scale_sentence_73

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 Earth were the subject of considerable debate. Geologic time scale_sentence_74

The first geologic time scale that included absolute dates was published in 1913 by the British geologist Arthur Holmes. Geologic time scale_sentence_75

He greatly furthered the newly created discipline of geochronology and published the world-renowned book The Age of the Earth in which he estimated Earth's age to be at least 1.6 billion years. Geologic time scale_sentence_76

In 1977, the Global Commission on Stratigraphy (now the International Commission on Stratigraphy) began to define global references known as GSSP (Global Boundary Stratotype Sections and Points) for geologic periods and faunal stages. Geologic time scale_sentence_77

The commission's work is described in the 2012 geologic time scale of Gradstein et al. Geologic time scale_sentence_78

A UML model for how the timescale is structured, relating it to the GSSP, is also available. Geologic time scale_sentence_79

The Anthropocene Geologic time scale_section_8

Popular culture and a growing number of scientists use the term "Anthropocene" informally to label the current epoch in which we are living. Geologic time scale_sentence_80

The term was coined by Paul Crutzen and Eugene Stoermer in 2000 to describe the current time in which humans have had an enormous impact on the environment. Geologic time scale_sentence_81

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. Geologic time scale_sentence_82

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. Geologic time scale_sentence_83

Others say that humans have not even started to leave their biggest impact on Earth, and therefore the Anthropocene has not even started yet. Geologic time scale_sentence_84

The ICS has not officially approved the term as of September 2015. Geologic time scale_sentence_85

The Anthropocene Working Group met in Oslo in April 2016 to consolidate evidence supporting the argument for the Anthropocene as a true geologic epoch. Geologic time scale_sentence_86

Evidence was evaluated and the group voted to recommend "Anthropocene" as the new geological age in August 2016. Geologic time scale_sentence_87

Should the International Commission 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 as part of the geologic time scale. Geologic time scale_sentence_88

Table of geologic time Geologic time scale_section_9

The following table summarizes the major events and characteristics of the periods of time making up the geologic time scale. Geologic time scale_sentence_89

This table is arranged with the most recent geologic periods at the top, and the oldest at the bottom. Geologic time scale_sentence_90

The height of each table entry does not correspond to the duration of each subdivision of time. Geologic time scale_sentence_91

The content of the table is based on the current official geologic time scale of the International Commission on Stratigraphy (ICS), with the epoch names altered to the early/late format from lower/upper as recommended by the ICS when dealing with chronostratigraphy. Geologic time scale_sentence_92

The ICS now provides an online, interactive, version of this chart too, , 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 Management and Application of Geoscience Information GeoSciML project as a service and at a SPARQL end-point. Geologic time scale_sentence_93

Please note that this is not to scale, and even though the Phanerozoic eon looks longer than the rest, it merely spans 500 million years, whilst the previous three eons (or the Precambrian supereon) collectively span over 3.5 billion years. Geologic time scale_sentence_94

This discrepancy is caused by the lack of action in the first three eons (or supereon) compared to ours (the Phanerozoic). Geologic time scale_sentence_95

Geologic time scale_table_general_0

SupereonGeologic time scale_header_cell_0_0_0 EonGeologic time scale_header_cell_0_0_1 EraGeologic time scale_header_cell_0_0_2 PeriodGeologic time scale_header_cell_0_0_3 EpochGeologic time scale_header_cell_0_0_4 AgeGeologic time scale_header_cell_0_0_5 Major eventsGeologic time scale_header_cell_0_0_6 Start, million years agoGeologic time scale_header_cell_0_0_7
n/aGeologic time scale_cell_0_1_0 PhanerozoicGeologic time scale_cell_0_1_1 CenozoicGeologic time scale_cell_0_1_2 QuaternaryGeologic time scale_cell_0_1_3 HoloceneGeologic time scale_cell_0_1_4 MeghalayanGeologic time scale_cell_0_1_5 4.2 kiloyear event, Little Ice Age, increasing industrial CO2.Geologic time scale_cell_0_1_6 0.0042Geologic time scale_cell_0_1_7
NorthgrippianGeologic time scale_cell_0_2_0 8.2 kiloyear event, Holocene climatic optimum. Bronze Age.Geologic time scale_cell_0_2_1 0.0082Geologic time scale_cell_0_2_2
GreenlandianGeologic time scale_cell_0_3_0 Current interglacial begins. Sea level flooding of Doggerland and Sundaland. Sahara desert forms. Neolithic agriculture.Geologic time scale_cell_0_3_1 0.0117Geologic time scale_cell_0_3_2
PleistoceneGeologic time scale_cell_0_4_0 Late ('Tarantian')Geologic time scale_cell_0_4_1 Eemian interglacial, Last glacial period, ending with Younger Dryas. Toba eruption. Megafauna extinction.Geologic time scale_cell_0_4_2 0.129Geologic time scale_cell_0_4_3
ChibanianGeologic time scale_cell_0_5_0 High amplitude 100 ka glacial cycles. Rise of Homo sapiens.Geologic time scale_cell_0_5_1 0.774Geologic time scale_cell_0_5_2
CalabrianGeologic time scale_cell_0_6_0 Further cooling of the climate. Spread of Homo erectus.Geologic time scale_cell_0_6_1 1.8Geologic time scale_cell_0_6_2
GelasianGeologic time scale_cell_0_7_0 Start of Quaternary glaciations. Rise of the Pleistocene megafauna and Homo habilis.Geologic time scale_cell_0_7_1 2.58Geologic time scale_cell_0_7_2
NeogeneGeologic time scale_cell_0_8_0 PlioceneGeologic time scale_cell_0_8_1 PiacenzianGeologic time scale_cell_0_8_2 Greenland ice sheet develops. Australopithecus common in East Africa.Geologic time scale_cell_0_8_3 3.6Geologic time scale_cell_0_8_4
ZancleanGeologic time scale_cell_0_9_0 Zanclean flooding of the Mediterranean Basin. Cooling climate. Ardipithecus in Africa.Geologic time scale_cell_0_9_1 5.333Geologic time scale_cell_0_9_2
MioceneGeologic time scale_cell_0_10_0 MessinianGeologic time scale_cell_0_10_1 Messinian Event with hypersaline lakes in empty Mediterranean Basin. Moderate Icehouse climate, punctuated by ice ages and re-establishment of East Antarctic Ice Sheet; Gradual separation of human and chimpanzee ancestors. Sahelanthropus tchadensis in Africa.Geologic time scale_cell_0_10_2 7.246Geologic time scale_cell_0_10_3
TortonianGeologic time scale_cell_0_11_0 11.63Geologic time scale_cell_0_11_1
SerravallianGeologic time scale_cell_0_12_0 Warmer during middle Miocene climate optimum. Extinctions in middle Miocene disruption.Geologic time scale_cell_0_12_1 13.82Geologic time scale_cell_0_12_2
LanghianGeologic time scale_cell_0_13_0 15.97Geologic time scale_cell_0_13_1
BurdigalianGeologic time scale_cell_0_14_0 Orogeny in Northern Hemisphere. Start of Kaikoura Orogeny forming Southern Alps in New Zealand. Widespread forests slowly draw in massive amounts of CO2, gradually lowering the level of atmospheric CO2 from 650 ppmv down to around 100 ppmv during the Miocene. Modern mammal and bird families become recognizable. Horses and mastodons diverse. Grasses become ubiquitous. Ancestor of apes, including humans.Geologic time scale_cell_0_14_1 20.44Geologic time scale_cell_0_14_2
AquitanianGeologic time scale_cell_0_15_0 23.03Geologic time scale_cell_0_15_1
PaleogeneGeologic time scale_cell_0_16_0 OligoceneGeologic time scale_cell_0_16_1 ChattianGeologic time scale_cell_0_16_2 Grande Coupure extinction. Start of widespread Antarctic glaciation. Rapid evolution and diversification of fauna, especially mammals. Major evolution and dispersal of modern types of flowering plantsGeologic time scale_cell_0_16_3 28.1Geologic time scale_cell_0_16_4
RupelianGeologic time scale_cell_0_17_0 33.9Geologic time scale_cell_0_17_1
EoceneGeologic time scale_cell_0_18_0 PriabonianGeologic time scale_cell_0_18_1 Moderate, cooling climate. Archaic mammals (e.g. Creodonts, "Condylarths", Uintatheres, etc.) flourish and continue to develop during the epoch. Appearance of several "modern" mammal families. Primitive whales diversify. Reglaciation of Antarctica and formation of its ice cap; End of Laramide and Sevier Orogenies of the Rocky Mountains in North America. Orogeny of the Alps in Europe begins. Hellenic Orogeny begins in Greece and Aegean Sea.Geologic time scale_cell_0_18_2 37.8Geologic time scale_cell_0_18_3
BartonianGeologic time scale_cell_0_19_0 41.2Geologic time scale_cell_0_19_1
LutetianGeologic time scale_cell_0_20_0 47.8Geologic time scale_cell_0_20_1
YpresianGeologic time scale_cell_0_21_0 Two transient events of global warming (PETM and ETM-2) and warming climate until the Eocene Climatic Optimum. The Azolla event decreased CO2 levels from 3500 ppm to 650 ppm, setting the stage for a long period of cooling. Indian Subcontinent collides with Asia and starts Himalayan Orogeny.Geologic time scale_cell_0_21_1 56Geologic time scale_cell_0_21_2
PaleoceneGeologic time scale_cell_0_22_0 ThanetianGeologic time scale_cell_0_22_1 Starts with Chicxulub impact and the K-Pg extinction event. Climate tropical. Modern plants appear; Mammals diversify into a number of lineages following the extinction of the non-avian dinosaurs. First large mammals (up to bear or small hippo size). Alpine orogeny in Europe and Asia begins.Geologic time scale_cell_0_22_2 59.2Geologic time scale_cell_0_22_3
SelandianGeologic time scale_cell_0_23_0 61.6Geologic time scale_cell_0_23_1
DanianGeologic time scale_cell_0_24_0 66Geologic time scale_cell_0_24_1
MesozoicGeologic time scale_cell_0_25_0 CretaceousGeologic time scale_cell_0_25_1 LateGeologic time scale_cell_0_25_2 MaastrichtianGeologic time scale_cell_0_25_3 Flowering plants proliferate, along with new types of insects. More modern teleost fish begin to appear. Ammonoidea, belemnites, rudist bivalves, echinoids and sponges all common. Many new types of dinosaurs (e.g. Tyrannosaurs, Titanosaurs, Hadrosaurs, and Ceratopsids) evolve on land, as do Eusuchia (modern crocodilians); and mosasaurs and modern sharks appear in the sea. Birds toothed and toothless coexist with pterosaurs. Monotremes, marsupials and placental mammals appear. Break up of Gondwana. Beginning of Laramide and Sevier Orogenies of the Rocky Mountains. atmospheric CO2 close to present-day levels.Geologic time scale_cell_0_25_4 72.1 ± 0.2Geologic time scale_cell_0_25_5
CampanianGeologic time scale_cell_0_26_0 83.6 ± 0.2Geologic time scale_cell_0_26_1
SantonianGeologic time scale_cell_0_27_0 86.3 ± 0.5Geologic time scale_cell_0_27_1
ConiacianGeologic time scale_cell_0_28_0 89.8 ± 0.3Geologic time scale_cell_0_28_1
TuronianGeologic time scale_cell_0_29_0 93.9Geologic time scale_cell_0_29_1
CenomanianGeologic time scale_cell_0_30_0 100.5Geologic time scale_cell_0_30_1
EarlyGeologic time scale_cell_0_31_0 AlbianGeologic time scale_cell_0_31_1 ~113Geologic time scale_cell_0_31_2
AptianGeologic time scale_cell_0_32_0 ~125Geologic time scale_cell_0_32_1
BarremianGeologic time scale_cell_0_33_0 ~129.4Geologic time scale_cell_0_33_1
HauterivianGeologic time scale_cell_0_34_0 ~132.9Geologic time scale_cell_0_34_1
ValanginianGeologic time scale_cell_0_35_0 ~139.8Geologic time scale_cell_0_35_1
BerriasianGeologic time scale_cell_0_36_0 ~145Geologic time scale_cell_0_36_1
JurassicGeologic time scale_cell_0_37_0 LateGeologic time scale_cell_0_37_1 TithonianGeologic time scale_cell_0_37_2 Gymnosperms (especially conifers, Bennettitales and cycads) and ferns common. Many types of dinosaurs, such as sauropods, carnosaurs, and stegosaurs. Mammals common but small. First birds and lizards. Ichthyosaurs and plesiosaurs diverse. Bivalves, Ammonites and belemnites abundant. Sea urchins very common, along with crinoids, starfish, sponges, and terebratulid and rhynchonellid brachiopods. Breakup of Pangaea into Gondwana and Laurasia. Nevadan orogeny in North America. Rangitata and Cimmerian orogenies taper off. Atmospheric CO2 levels 3–4 times the present day levels (1200–1500 ppmv, compared to today's 400 ppmv).Geologic time scale_cell_0_37_3 152.1 ± 0.9Geologic time scale_cell_0_37_4
KimmeridgianGeologic time scale_cell_0_38_0 157.3 ± 1.0Geologic time scale_cell_0_38_1
OxfordianGeologic time scale_cell_0_39_0 163.5 ± 1.0Geologic time scale_cell_0_39_1
MiddleGeologic time scale_cell_0_40_0 CallovianGeologic time scale_cell_0_40_1 166.1 ± 1.2Geologic time scale_cell_0_40_2
BathonianGeologic time scale_cell_0_41_0 168.3 ± 1.3Geologic time scale_cell_0_41_1
BajocianGeologic time scale_cell_0_42_0 170.3 ± 1.4Geologic time scale_cell_0_42_1
AalenianGeologic time scale_cell_0_43_0 174.1 ± 1.0Geologic time scale_cell_0_43_1
EarlyGeologic time scale_cell_0_44_0 ToarcianGeologic time scale_cell_0_44_1 182.7 ± 0.7Geologic time scale_cell_0_44_2
PliensbachianGeologic time scale_cell_0_45_0 190.8 ± 1.0Geologic time scale_cell_0_45_1
SinemurianGeologic time scale_cell_0_46_0 199.3 ± 0.3Geologic time scale_cell_0_46_1
HettangianGeologic time scale_cell_0_47_0 201.3 ± 0.2Geologic time scale_cell_0_47_1
TriassicGeologic time scale_cell_0_48_0 LateGeologic time scale_cell_0_48_1 RhaetianGeologic time scale_cell_0_48_2 Archosaurs dominant on land as dinosaurs and in the air as pterosaurs. Ichthyosaurs and nothosaurs dominate large marine fauna. Cynodonts become smaller and more mammal-like, while first mammals and crocodilia appear. Dicroidiumflora common on land. Many large aquatic temnospondyl amphibians. Ceratitic ammonoids extremely common. Modern corals and teleost fish appear, as do many modern insect clades. Andean Orogeny 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)Geologic time scale_cell_0_48_3 ~208.5Geologic time scale_cell_0_48_4
NorianGeologic time scale_cell_0_49_0 ~227Geologic time scale_cell_0_49_1
CarnianGeologic time scale_cell_0_50_0 ~237Geologic time scale_cell_0_50_1
MiddleGeologic time scale_cell_0_51_0 LadinianGeologic time scale_cell_0_51_1 ~242Geologic time scale_cell_0_51_2
AnisianGeologic time scale_cell_0_52_0 247.2Geologic time scale_cell_0_52_1
EarlyGeologic time scale_cell_0_53_0 OlenekianGeologic time scale_cell_0_53_1 251.2Geologic time scale_cell_0_53_2
InduanGeologic time scale_cell_0_54_0 251.902 ± 0.06Geologic time scale_cell_0_54_1
PaleozoicGeologic time scale_cell_0_55_0 PermianGeologic time scale_cell_0_55_1 LopingianGeologic time scale_cell_0_55_2 ChanghsingianGeologic time scale_cell_0_55_3 Landmasses unite into supercontinent Pangaea, creating the Appalachians. End of Permo-Carboniferous glaciation. Synapsids including (pelycosaurs and therapsids) become plentiful, while parareptiles and temnospondyl amphibians remain common. In the mid-Permian, coal-age flora are replaced by cone-bearing gymnosperms (the first true seed plants) and by the first true mosses. Beetles and flies evolve. Marine life flourishes in warm shallow reefs; productid and spiriferid brachiopods, bivalves, forams, and ammonoids all abundant. Permian-Triassic extinction event occurs 251 Ma: 95% of life on Earth becomes extinct, including all trilobites, graptolites, and blastoids. 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.Geologic time scale_cell_0_55_4 254.14 ± 0.07Geologic time scale_cell_0_55_5
WuchiapingianGeologic time scale_cell_0_56_0 259.1 ± 0.4Geologic time scale_cell_0_56_1
GuadalupianGeologic time scale_cell_0_57_0 CapitanianGeologic time scale_cell_0_57_1 265.1 ± 0.4Geologic time scale_cell_0_57_2
WordianGeologic time scale_cell_0_58_0 268.8 ± 0.5Geologic time scale_cell_0_58_1
RoadianGeologic time scale_cell_0_59_0 272.95 ± 0.5Geologic time scale_cell_0_59_1
CisuralianGeologic time scale_cell_0_60_0 KungurianGeologic time scale_cell_0_60_1 283.5 ± 0.6Geologic time scale_cell_0_60_2
ArtinskianGeologic time scale_cell_0_61_0 290.1 ± 0.26Geologic time scale_cell_0_61_1
SakmarianGeologic time scale_cell_0_62_0 295 ± 0.18Geologic time scale_cell_0_62_1
AsselianGeologic time scale_cell_0_63_0 298.9 ± 0.15Geologic time scale_cell_0_63_1
Carbon- iferousGeologic time scale_cell_0_64_0 PennsylvanianGeologic time scale_cell_0_64_1 GzhelianGeologic time scale_cell_0_64_2 Winged insects radiate suddenly; some (esp. Protodonata and Palaeodictyoptera) are quite large. Amphibians common and diverse. First reptiles and coal forests (scale trees, ferns, club trees, giant horsetails, Cordaites, etc.). Highest-ever atmospheric oxygen levels. Goniatites, brachiopods, bryozoa, bivalves, and corals plentiful in the seas and oceans. Testate forams proliferate. Uralian orogeny in Europe and Asia. Variscan orogeny occurs towards middle and late Mississippian Periods.Geologic time scale_cell_0_64_3 303.7 ± 0.1Geologic time scale_cell_0_64_4
KasimovianGeologic time scale_cell_0_65_0 307 ± 0.1Geologic time scale_cell_0_65_1
MoscovianGeologic time scale_cell_0_66_0 315.2 ± 0.2Geologic time scale_cell_0_66_1
BashkirianGeologic time scale_cell_0_67_0 323.2 ± 0.4Geologic time scale_cell_0_67_1
MississippianGeologic time scale_cell_0_68_0 SerpukhovianGeologic time scale_cell_0_68_1 Large primitive trees, first land vertebrates, and amphibious sea-scorpions live amid coal-forming coastal swamps. Lobe-finned rhizodonts are dominant big fresh-water predators. In the oceans, early sharks are common and quite diverse; echinoderms (especially crinoids and blastoids) abundant. Corals, bryozoa, goniatites and brachiopods (Productida, Spiriferida, etc.) very common, but trilobites and nautiloids decline. Glaciation in East Gondwana. Tuhua Orogeny in New Zealand tapers off.Geologic time scale_cell_0_68_2 330.9 ± 0.2Geologic time scale_cell_0_68_3
ViséanGeologic time scale_cell_0_69_0 346.7 ± 0.4Geologic time scale_cell_0_69_1
TournaisianGeologic time scale_cell_0_70_0 358.9 ± 0.4Geologic time scale_cell_0_70_1
DevonianGeologic time scale_cell_0_71_0 LateGeologic time scale_cell_0_71_1 FamennianGeologic time scale_cell_0_71_2 First clubmosses, horsetails and ferns appear, as do the first seed-bearing plants (progymnosperms), first trees (the progymnosperm Archaeopteris), and first (wingless) insects. Strophomenid and atrypid brachiopods, rugose and tabulate corals, and crinoids are all abundant in the oceans. Goniatite ammonoids are plentiful, while squid-like coleoids arise. Trilobites and armoured agnaths decline, while jawed fishes (placoderms, lobe-finned and ray-finned fish, and early sharks) rule the seas. First tetrapods still aquatic. "Old Red Continent" of Euramerica. Beginning of Acadian Orogeny for Anti-Atlas Mountains of North Africa, and Appalachian Mountains of North America, also the Antler, Variscan, and Tuhua Orogeny in New Zealand.Geologic time scale_cell_0_71_3 372.2 ± 1.6Geologic time scale_cell_0_71_4
FrasnianGeologic time scale_cell_0_72_0 382.7 ± 1.6Geologic time scale_cell_0_72_1
MiddleGeologic time scale_cell_0_73_0 GivetianGeologic time scale_cell_0_73_1 387.7 ± 0.8Geologic time scale_cell_0_73_2
EifelianGeologic time scale_cell_0_74_0 393.3 ± 1.2Geologic time scale_cell_0_74_1
EarlyGeologic time scale_cell_0_75_0 EmsianGeologic time scale_cell_0_75_1 407.6 ± 2.6Geologic time scale_cell_0_75_2
PragianGeologic time scale_cell_0_76_0 410.8 ± 2.8Geologic time scale_cell_0_76_1
LochkovianGeologic time scale_cell_0_77_0 419.2 ± 3.2Geologic time scale_cell_0_77_1
SilurianGeologic time scale_cell_0_78_0 PridoliGeologic time scale_cell_0_78_1 First vascular plants (the rhyniophytes and their relatives), first millipedes and arthropleurids on land. First jawed fishes, as well as many armoured jawless fish, populate the seas. Sea-scorpions reach large size. Tabulate and rugose corals, brachiopods (Pentamerida, Rhynchonellida, etc.), and crinoids all abundant. Trilobites and mollusks diverse; graptolites not as varied. Beginning of Caledonian Orogeny for hills in England, Ireland, Wales, Scotland, and the Scandinavian Mountains. Also continued into Devonian period as the Acadian Orogeny, above. Taconic Orogeny tapers off. Lachlan Orogeny on Australian continent tapers off.Geologic time scale_cell_0_78_3 423 ± 2.3Geologic time scale_cell_0_78_4
LudlowGeologic time scale_cell_0_79_0 LudfordianGeologic time scale_cell_0_79_1 425.6 ± 0.9Geologic time scale_cell_0_79_2
GorstianGeologic time scale_cell_0_80_0 427.4 ± 0.5Geologic time scale_cell_0_80_1
WenlockGeologic time scale_cell_0_81_0 HomerianGeologic time scale_cell_0_81_1 430.5 ± 0.7Geologic time scale_cell_0_81_2
SheinwoodianGeologic time scale_cell_0_82_0 433.4 ± 0.8Geologic time scale_cell_0_82_1
LlandoveryGeologic time scale_cell_0_83_0 TelychianGeologic time scale_cell_0_83_1 438.5 ± 1.1Geologic time scale_cell_0_83_2
AeronianGeologic time scale_cell_0_84_0 440.8 ± 1.2Geologic time scale_cell_0_84_1
RhuddanianGeologic time scale_cell_0_85_0 443.8 ± 1.5Geologic time scale_cell_0_85_1
OrdovicianGeologic time scale_cell_0_86_0 LateGeologic time scale_cell_0_86_1 HirnantianGeologic time scale_cell_0_86_2 Invertebrates diversify into many new types (e.g., long straight-shelled cephalopods). Early corals, articulate brachiopods (Orthida, Strophomenida, etc.), bivalves, nautiloids, trilobites, ostracods, bryozoa, many types of echinoderms (crinoids, cystoids, starfish, etc.), branched graptolites, and other taxa all common. Conodonts (early planktonic vertebrates) appear. First green plants and fungi on land. Ice age at end of period.Geologic time scale_cell_0_86_3 445.2 ± 1.4Geologic time scale_cell_0_86_4
KatianGeologic time scale_cell_0_87_0 453 ± 0.7Geologic time scale_cell_0_87_1
SandbianGeologic time scale_cell_0_88_0 458.4 ± 0.9Geologic time scale_cell_0_88_1
MiddleGeologic time scale_cell_0_89_0 DarriwilianGeologic time scale_cell_0_89_1 467.3 ± 1.1Geologic time scale_cell_0_89_2
DapingianGeologic time scale_cell_0_90_0 470 ± 1.4Geologic time scale_cell_0_90_1
EarlyGeologic time scale_cell_0_91_0 Floian

(formerly Arenig)Geologic time scale_cell_0_91_1

477.7 ± 1.4Geologic time scale_cell_0_91_2
TremadocianGeologic time scale_cell_0_92_0 485.4 ± 1.9Geologic time scale_cell_0_92_1
CambrianGeologic time scale_cell_0_93_0 FurongianGeologic time scale_cell_0_93_1 Stage 10Geologic time scale_cell_0_93_2 Major diversification of life in the Cambrian Explosion. Numerous fossils; most modern animal phyla appear. First chordates appear, along with a number of extinct, problematic phyla. Reef-building Archaeocyatha abundant; then vanish. Trilobites, priapulid worms, sponges, inarticulate brachiopods (unhinged lampshells), and numerous other animals. Anomalocarids are giant predators, while many Ediacaran fauna die out. Prokaryotes, protists (e.g., forams), fungi and algae continue to present day. Gondwana emerges. 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. Atmospheric CO2 content roughly 15 times present-day (Holocene) levels (6000 ppmv compared to today's 400 ppmv)Geologic time scale_cell_0_93_3 ~489.5Geologic time scale_cell_0_93_4
JiangshanianGeologic time scale_cell_0_94_0 ~494Geologic time scale_cell_0_94_1
PaibianGeologic time scale_cell_0_95_0 ~497Geologic time scale_cell_0_95_1
MiaolingianGeologic time scale_cell_0_96_0 GuzhangianGeologic time scale_cell_0_96_1 ~500.5Geologic time scale_cell_0_96_2
DrumianGeologic time scale_cell_0_97_0 ~504.5Geologic time scale_cell_0_97_1
WuliuanGeologic time scale_cell_0_98_0 ~509Geologic time scale_cell_0_98_1
Series 2Geologic time scale_cell_0_99_0 Stage 4Geologic time scale_cell_0_99_1 ~514Geologic time scale_cell_0_99_2
Stage 3Geologic time scale_cell_0_100_0 ~521Geologic time scale_cell_0_100_1
TerreneuvianGeologic time scale_cell_0_101_0 Stage 2Geologic time scale_cell_0_101_1 ~529Geologic time scale_cell_0_101_2
FortunianGeologic time scale_cell_0_102_0 ~541 ± 1.0Geologic time scale_cell_0_102_1
PrecambrianGeologic time scale_cell_0_103_0 ProterozoicGeologic time scale_cell_0_103_1 NeoproterozoicGeologic time scale_cell_0_103_2 EdiacaranGeologic time scale_cell_0_103_3 Good fossils of the first multi-celled animals. Ediacaran biota flourish worldwide in seas. Simple trace fossils of possible worm-like Trichophycus, etc. First sponges and trilobitomorphs. Enigmatic forms include many soft-jellied creatures shaped like bags, disks, or quilts (like Dickinsonia). Taconic Orogeny in North America. Aravalli Range orogeny in Indian Subcontinent. Beginning of Petermann Orogeny on Australian continent. Beardmore Orogeny in Antarctica, 633–620 Ma.Geologic time scale_cell_0_103_4 ~635Geologic time scale_cell_0_103_7
CryogenianGeologic time scale_cell_0_104_0 Possible "Snowball Earth" period. Fossils still rare. Rodinia landmass begins to break up. Late Ruker / Nimrod Orogeny in Antarctica tapers off.Geologic time scale_cell_0_104_1 ~720Geologic time scale_cell_0_104_4
TonianGeologic time scale_cell_0_105_0 Rodinia supercontinent persists. Sveconorwegian orogeny ends. Trace fossils of simple multi-celled eukaryotes. First radiation of dinoflagellate-like acritarchs. Grenville Orogeny tapers off in North America. Pan-African orogeny in Africa. 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.Geologic time scale_cell_0_105_1 1000Geologic time scale_cell_0_105_4
MesoproterozoicGeologic time scale_cell_0_106_0 StenianGeologic time scale_cell_0_106_1 Narrow highly metamorphic belts due to orogeny as Rodinia forms. Sveconorwegian orogeny starts. Late Ruker / Nimrod Orogeny in Antarctica possibly begins. Musgrave Orogeny (c. 1,080 Ma), Musgrave Block, Central Australia.Geologic time scale_cell_0_106_2 1200Geologic time scale_cell_0_106_5
EctasianGeologic time scale_cell_0_107_0 Platform covers continue to expand. Green algae colonies in the seas. Grenville Orogeny in North America.Geologic time scale_cell_0_107_1 1400Geologic time scale_cell_0_107_4
CalymmianGeologic time scale_cell_0_108_0 Platform covers expand. Barramundi Orogeny, McArthur Basin, Northern Australia, and Isan Orogeny, c.1,600 Ma, Mount Isa Block, QueenslandGeologic time scale_cell_0_108_1 1600Geologic time scale_cell_0_108_4
PaleoproterozoicGeologic time scale_cell_0_109_0 StatherianGeologic time scale_cell_0_109_1 First complex single-celled life: protists with nuclei, Francevillian biota. Columbia is the primordial 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.Geologic time scale_cell_0_109_2 1800Geologic time scale_cell_0_109_5
OrosirianGeologic time scale_cell_0_110_0 The atmosphere becomes oxygenic. Vredefort and Sudbury Basin asteroid impacts. Much orogeny. Penokean and Trans-Hudsonian Orogenies in North America. Early Ruker Orogeny in Antarctica, 2,000–1,700 Ma. Glenburgh Orogeny, Glenburgh Terrane, Australian continent c. 2,005–1,920 Ma. Kimban Orogeny, Gawler craton in Australian continent begins.Geologic time scale_cell_0_110_1 2050Geologic time scale_cell_0_110_4
RhyacianGeologic time scale_cell_0_111_0 Bushveld Igneous Complex forms. Huronian glaciation.Geologic time scale_cell_0_111_1 2300Geologic time scale_cell_0_111_4
SiderianGeologic time scale_cell_0_112_0 Oxygen catastrophe: banded iron formations forms. Sleaford Orogeny on Australian continent, Gawler Craton 2,440–2,420 Ma.Geologic time scale_cell_0_112_1 2500Geologic time scale_cell_0_112_4
ArcheanGeologic time scale_cell_0_113_0 NeoarcheanGeologic time scale_cell_0_113_1 Stabilization of most modern cratons; possible mantle overturn event. Insell Orogeny, 2,650 ± 150 Ma. Abitibi greenstone belt in present-day Ontario and Quebec begins to form, stabilizes by 2,600 Ma.Geologic time scale_cell_0_113_2 2800Geologic time scale_cell_0_113_6
MesoarcheanGeologic time scale_cell_0_114_0 First stromatolites (probably colonial cyanobacteria). Oldest macrofossils. Humboldt Orogeny in Antarctica. Blake River Megacaldera Complex begins to form in present-day Ontario and Quebec, ends by roughly 2,696 Ma.Geologic time scale_cell_0_114_1 3200Geologic time scale_cell_0_114_5
PaleoarcheanGeologic time scale_cell_0_115_0 First known oxygen-producing bacteria. Oldest definitive microfossils. Oldest cratons on Earth (such as the Canadian Shield and the Pilbara Craton) may have formed during this period. Rayner Orogeny in Antarctica.Geologic time scale_cell_0_115_1 3600Geologic time scale_cell_0_115_5
EoarcheanGeologic time scale_cell_0_116_0 Simple single-celled life (probably bacteria and archaea). Oldest probable microfossils. The first life forms and self-replicating RNA molecules evolve around 4,000 Ma, after the Late Heavy Bombardment ends on Earth. Napier Orogeny in Antarctica, 4,000 ± 200 Ma.Geologic time scale_cell_0_116_1 ~4000Geologic time scale_cell_0_116_5
HadeanGeologic time scale_cell_0_117_0 Early Imbrian (Neohadean) (unofficial)Geologic time scale_cell_0_117_1 Indirect photosynthetic evidence (e.g., kerogen) of primordial life. This era overlaps the beginning of the Late Heavy Bombardment of the Inner Solar System, produced possibly by the planetary migration of Neptune into the Kuiper belt as a result of orbital resonances between Jupiter and Saturn. Oldest known rock (4,031 to 3,580 Ma).Geologic time scale_cell_0_117_2 4130Geologic time scale_cell_0_117_6
Nectarian (Mesohadean) (unofficial)Geologic time scale_cell_0_118_0 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 form by big impact events. Earliest evidence for life based on unusually high amounts of light isotopes of carbon, a common sign of life.Geologic time scale_cell_0_118_1 4280Geologic time scale_cell_0_118_5
Basin Groups (Paleohadean) (unofficial)Geologic time scale_cell_0_119_0 End of the Early Bombardment Phase. Oldest known mineral (Zircon, 4,404 ± 8 Ma). Asteroids and comets bring water to Earth.Geologic time scale_cell_0_119_1 4533Geologic time scale_cell_0_119_5
Cryptic (Eohadean) (unofficial)Geologic time scale_cell_0_120_0 Formation of Moon (4,533 to 4,527 Ma), probably from giant impact, since the end of this era. Formation of Earth (4,570 to 4,567.17 Ma), Early Bombardment Phase begins. Formation of Sun (4,680 to 4,630 Ma) .Geologic time scale_cell_0_120_1 4600Geologic time scale_cell_0_120_5

Proposed Precambrian timeline Geologic time scale_section_10

The ICS's Geologic Time Scale 2012 book which includes the new approved time scale also displays a proposal to substantially revise the Precambrian time scale to reflect important events such as the formation of the Earth or the Great Oxidation Event, among others, while at the same time maintaining most of the previous chronostratigraphic nomenclature for the pertinent time span. Geologic time scale_sentence_96

(See also Period (geology)#Structure.) Geologic time scale_sentence_97

Geologic time scale_unordered_list_1

  • Hadean Eon – 4600–4031 MaGeologic time scale_item_1_3
    • Chaotian Era – 4600–4404 Ma – the name alluding both to the mythological Chaos and the chaotic phase of planet formationGeologic time scale_item_1_4
    • Jack Hillsian or Zirconian Era – 4404–4031 Ma – both names allude to the Jack Hills Greenstone Belt which provided the oldest mineral grains on Earth, zirconsGeologic time scale_item_1_5
  • Archean Eon – 4031–2420 MaGeologic time scale_item_1_6
    • Paleoarchean Era – 4031–3490 MaGeologic time scale_item_1_7
    • Mesoarchean Era – 3490–2780 MaGeologic time scale_item_1_10
      • Vaalbaran Period – 3490–3020 Ma – based on the names of the Kapvaal (Southern Africa) and Pilbara (Western Australia) cratonsGeologic time scale_item_1_11
      • Pongolan Period – 3020–2780 Ma – named after the Pongola SupergroupGeologic time scale_item_1_12
    • Neoarchean Era – 2780–2420 MaGeologic time scale_item_1_13
      • Methanian Period – 2780–2630 Ma – named for the inferred predominance of methanotrophic prokaryotesGeologic time scale_item_1_14
      • Siderian Period – 2630–2420 Ma – named for the voluminous banded iron formations formed within its durationGeologic time scale_item_1_15
  • Proterozoic Eon – 2420–541 MaGeologic time scale_item_1_16
    • Paleoproterozoic Era – 2420–1780 MaGeologic time scale_item_1_17
      • Oxygenian Period – 2420–2250 Ma – named for displaying the first evidence for a global oxidizing atmosphereGeologic time scale_item_1_18
      • Jatulian or Eukaryian Period – 2250–2060 Ma – names are respectively for the Lomagundi–Jatuli δC isotopic excursion event spanning its duration, and for the (proposed) first fossil appearance of eukaryotesGeologic time scale_item_1_19
      • Columbian Period – 2060–1780 Ma – named after the supercontinent ColumbiaGeologic time scale_item_1_20
    • Mesoproterozoic Era – 1780–850 MaGeologic time scale_item_1_21
      • Rodinian Period – 1780–850 Ma – named after the supercontinent Rodinia, stable environmentGeologic time scale_item_1_22
    • Neoproterozoic Era – 850–541 MaGeologic time scale_item_1_23
      • Cryogenian Period – 850–630 Ma – named for the occurrence of several glaciationsGeologic time scale_item_1_24
      • Ediacaran Period – 630–541 MaGeologic time scale_item_1_25

Shown to scale: Geologic time scale_sentence_98

Compare with the current official timeline, not shown to scale: Geologic time scale_sentence_99

See also Geologic time scale_section_11

Credits to the contents of this page go to the authors of the corresponding Wikipedia page: time scale.