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[[File:Geologic time scale - spiral - ICS colours (light) - path text.svg|upright=1.35|alt=Geologic time scale proportionally represented as a log-spiral. The image also shows some notable events in Earth's history and the general evolution of life.|thumb|The geologic time scale, proportionally represented as a [[Logarithmic spiral|log-spiral]] with some major events in Earth's history. A [[ | [[File:Geologic time scale - spiral - ICS colours (light) - path text.svg|upright=1.35|alt=Geologic time scale proportionally represented as a log-spiral. The image also shows some notable events in Earth's history and the general evolution of life.|thumb|The geologic time scale, proportionally represented as a [[Logarithmic spiral|log-spiral]] with some major events in Earth's history. A [[megaannum]] (Ma) represents one million (10<sup>6</sup>) years.]] | ||
The '''geologic time scale''' or '''geological time scale''' | The '''geologic time scale''' or '''geological time scale''' describes how geologic time is divided into standardised intervals. It uses the rock record together with the principles of [[chronostratigraphy]] to place rock sequences into their relative age positions, and [[geochronology]] techniques, such as [[radiometric dating]], to precisely date the boundaries between them. It is used primarily by [[Earth science|Earth scientists]] (including [[geologist]]s, [[paleontology|paleontologists]], [[geophysics|geophysicists]], [[geochemistry|geochemists]], and [[paleoclimatology|paleoclimatologists]]) 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|lithologies]], [[paleomagnetism|paleomagnetic]] properties, and [[fossil]]s. 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<ref name="ICS_statutes">{{Cite web |title=Statues & Guidelines |url=https://stratigraphy.org/statutes |access-date=2022-04-05 |website= |publisher=International Commission on Stratigraphy}}</ref> is to precisely define global chronostratigraphic units of the International Chronostratigraphic Chart (ICC){{ref icc}} that are used to define divisions of geological time. The chronostratigraphic divisions are in turn used to define geochronologic units.<ref name="ICS" /> | ||
== Principles == | == Principles == | ||
{{See also|Age of Earth|History of Earth|Geological history of Earth}} | {{See also|Age of Earth|History of Earth|Geological history of Earth}} | ||
The geologic time scale is a way of representing [[deep time]] based on events that have occurred | The geologic time scale is a way of representing [[deep time]] based on events that have occurred throughout [[History of Earth|Earth's history]], a time span of about [[Age of Earth|4.54 ± 0.05 billion years]].<ref name="Dalrymple 2001 AoE">{{cite journal |last=Dalrymple |first=G. Brent |date=2001 |title=The age of the Earth in the twentieth century: a problem (mostly) solved |journal=Special Publications, Geological Society of London |volume=190 |issue=1 |pages=205–221 |bibcode=2001GSLSP.190..205D |doi=10.1144/GSL.SP.2001.190.01.14 }} | ||
</ref> It | </ref> It arranges the rock record in chronological order by observing fundamental changes in stratigraphy that correspond to major geological or paleontological events. It combines the disciplines of chronostratigraphy, which studies the relationships between rock sequences to determine their relative ages,<ref name="ICS_chronostrat">{{Cite web |title=Chapter 9. Chronostratigraphic Units |url=https://stratigraphy.org/guide/chron |access-date=2022-04-02 |website=stratigraphy.org |publisher=International Commission on Stratigraphy}}</ref> and geochronology, the science of dating rocks and other geological materials.<ref name="ICS_definitions">{{Cite web |title=Chapter 3. Definitions and Procedures |url=https://stratigraphy.org/guide/defs |access-date=2022-04-02 |website=stratigraphy.org |publisher=International Commission on Stratigraphy}}</ref> | ||
=== Chronostratigraphy === | |||
Chronostratigraphy is the branch of [[stratigraphy]] that organises all the rocks of the [[Earth's crust]] into groups, known as chronostratigraphic units, based on their relative ages.<ref name="ICS_chronostrat" /> A chronostratigraphic unit includes all rock sequences globally that were deposited during a particular time interval.<ref name=":1" /> | |||
Chronostratigraphy uses several key principles to determine the relative relationships of rocks and thus their chronostratigraphic position in the rock record.<ref name="ICS_chronostratigraphic_units">{{Cite web |title=International Commission on Stratigraphy - Stratigraphic Guide - Chapter 9. Chronostratigraphic Units |url=https://stratigraphy.org/guide/chron |access-date=2024-04-16 |website=stratigraphy.org}}</ref><ref name="Boggs-2011">{{Cite book |last=Boggs |first=Sam |title=Principles of sedimentology and stratigraphy |date=2011 |publisher=Prentice Hall |isbn=978-0-321-74576-7 |edition=5th |location=Boston, Munich}}</ref> | |||
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.<ref name="Steno_1669" /><ref name="Hutton_1795v1" /><ref name="Lyell_1832v1" /><ref name="Boggs-2011" /> In practice, this means a younger rock will lie on top of an older rock unless there is evidence to suggest otherwise. | * 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.<ref name="Steno_1669" /><ref name="Hutton_1795v1" /><ref name="Lyell_1832v1" /><ref name="Boggs-2011" /> 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.<ref name="Steno_1669" /><ref name="Lyell_1832v1" /><ref name="Boggs-2011" /> However, it is now known that not all sedimentary layers are deposited purely horizontally,<ref name="Boggs-2011" /><ref name="Mehta_et_al_1994">{{cite journal |last1=Mehta |first1=A |last2=Barker |first2=G C |title=The dynamics of sand |journal=Reports on Progress in Physics |date=April 1994 |volume=57 |issue=4 |pages=383–416 |doi=10.1088/0034-4885/57/4/002 |bibcode=1994RPPh...57..383M }}</ref> 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.<ref name="Steno_1669" /> 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 ''[[cross-cutting relationships|principle of cross-cutting relationships]]'' that states a rock that cuts across another rock must be younger than the rock it cuts across.<ref name="Steno_1669" /><ref name="Hutton_1795v1" /><ref name="Lyell_1832v1" /><ref name="Boggs-2011" /> | |||
* 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.<ref name="Lyell_1832v1" /><ref name="Boggs-2011" /> | |||
* The ''[[unconformity|relationships of unconformities]]'' 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.<ref name="Boggs-2011" /> 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.<ref name="Smith_1816">{{cite book |last1=Smith |first1=William |title=Strata identified by organized fossils: Containing prints on colored paper of the most characteristic specimens in each stratum |date=1816 |doi=10.5962/bhl.title.106808 |oclc=654668607 }}{{page needed|date=March 2026}}</ref><ref name="Boggs-2011" /> This allows for a correlation of strata even when the horizon between them is not continuous. | |||
=== Geochronology === | |||
Geochronology is the study of geological time. It uses quantitative measurements ([[geochronometry]]), such as radiometric dating, to provide precise ages, and relative methods of dating (e.g. [[paleomagnetism]] and [[stable isotope ratio]]s) to establish a timeframe for events in Earth's history.<ref name="ICS_definitions" /><ref name="ICS_chronostratigraphic_units" /> A geochronologic unit is an interval of time during which a chronostratigraphic unit formed.<ref name=":1" /> For example, all the rocks of the [[Silurian]] System (a chronostratigraphic unit) were deposited during the Silurian Period (a geochronologic unit).<ref name="Nichols_2009">{{Cite book |last=Nichols |first=Gary |title=Sedimentology and stratigraphy |date=2010 |publisher=Wiley-Blackwell |isbn=978-1-4051-3592-4 |edition=2. ed., [Nachdr.] |location=Chichester}}</ref> | |||
The | The age of a geochronologic unit can be refined and changed by improved dating techniques. However, the equivalent chronostratigraphic unit boundary remains unchanged.<ref name="ICS" /><ref name="Nichols_2009" /> For example, in early 2022, the base of the [[Cambrian]] Period (a geochronologic unit) 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.<ref name="ICS" /> | ||
The | === Global Boundary Stratotype Section and Point (GSSP) === | ||
Historically, regional geologic time scales were used<ref name="GTS2012_Precambrian">{{cite book |last1=Van Kranendonk |first1=Martin J. |title=The Geologic Time Scale |chapter=A Chronostratigraphic Division of the Precambrian |date=2012 |pages=299–392 |doi=10.1016/b978-0-444-59425-9.00016-0 |isbn=978-0-444-59425-9 |chapter-url={{GBurl|usoqlA8AVDUC|p=299}} }}</ref> 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 [[horizon (geology)|horizons]] that can be used to define the lower boundaries of chronostratigraphic units.<ref name="ICS_chronostratigraphic_units" /> A [[Global Boundary Stratotype Section and Point]] (GSSP) defines the lower boundary of a stage as being at a precise point in a specific rock succession in a particular geographic location. These reference points are known informally as "golden" spikes.<ref name="Nichols_2009" /> All the beds above the spike belong to one time interval and all those below it to another. This allows beds of a similar age around the world to be correlated with the strata that contain the golden spike. For example, the [[iridium anomaly]] produced by the [[Chicxulub crater|Chicxulub asteroid impact]] marks the lower boundary of the [[Paleogene]] System and thus the boundary between the Cretaceous and Paleogene. Whilst the GSSP is defined at Oued Djerfane in Tunisia, strata containing the iridium anomaly are found worldwide.<ref>{{cite book |last1=Vandenberghe |first1=N. |last2=Hilgen |first2=F.J. |last3=Speijer |first3=R.P. |last4=Ogg |first4=J.G. |last5=Gradstein |first5=F.M. |last6=Hammer |first6=O. |last7=Hollis |first7=C.J. |last8=Hooker |first8=J.J. |title=The Geologic Time Scale |chapter=The Paleogene Period |date=2012 |pages=855–921 |doi=10.1016/B978-0-444-59425-9.00028-7 |isbn=978-0-444-59425-9 }}</ref> | |||
The | The Proterozoic (apart from the Ediacaran), Archean and Hadean are subdivided by absolute ages ([[Global Standard Stratigraphic Age]]s) rather than geological features.<ref name="ICS_chronostratigraphic_units" /> Proposals have been made to better reconcile these divisions with the rock record.<ref name="Shields_2022_pre-Cryogenian">{{Cite journal |last1=Shields |first1=Graham A. |last2=Strachan |first2=Robin A. |last3=Porter |first3=Susannah M. |last4=Halverson |first4=Galen P. |last5=Macdonald |first5=Francis A. |last6=Plumb |first6=Kenneth A. |last7=de Alvarenga |first7=Carlos J. |last8=Banerjee |first8=Dhiraj M. |last9=Bekker |first9=Andrey |last10=Bleeker |first10=Wouter |last11=Brasier |first11=Alexander |date=2022 |title=A template for an improved rock-based subdivision of the pre-Cryogenian timescale |journal=Journal of the Geological Society |volume=179 |issue=1 |pages=jgs2020–222 |doi=10.1144/jgs2020-222 |bibcode=2022JGSoc.179..222S |doi-access=free }}</ref><ref name="GTS2012_Precambrian" /> | ||
== Divisions of geologic time == | == Divisions of geologic time == | ||
{{See also|Stratigraphy|Chronostratigraphy|Biostratigraphy|Magnetostratigraphy|Lithostratigraphy|Geochronology}} | {{See also|Stratigraphy|Chronostratigraphy|Biostratigraphy|Magnetostratigraphy|Lithostratigraphy|Geochronology}} | ||
The geologic time scale is divided into chronostratigraphic units and their corresponding geochronologic units | 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 Chronostratigraphic Chart are represented by the unit [[Megaannum|Ma]] (megaannum, for 'million [[year]]s'). For example, {{Period start|Jurassic}} {{Period start error|Jurassic}} 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|SI prefix]] units commonly used by geologists are [[Gigaannum|Ga]] (gigaannum, billion years), and [[Kiloannums|ka]] (kiloannum, thousand years), with the latter often represented in calibrated units ([[Before Present|before present]]).<ref name="ICS_definitions" /> | ||
The geologic time scale is divided into chronostratigraphic units and their corresponding geochronologic units: | |||
* An '''{{visible anchor|eon}}''' is the largest geochronologic time unit and is equivalent to a chronostratigraphic [[eonothem]].<ref name="dictionary_of_geology_2020">{{Cite book |title=A dictionary of geology and earth sciences |date=2020 |author=Michael Allaby |isbn=978-0-19-187490-1 |edition=Fifth |location=Oxford |oclc=1137380460}}</ref> There are four formally defined eons: the [[Hadean]], [[Archean]], [[Proterozoic]] and [[Phanerozoic]].<ref name=" | * An '''{{visible anchor|eon}}''' is the largest geochronologic time unit and is equivalent to a chronostratigraphic [[eonothem]].<ref name="dictionary_of_geology_2020">{{Cite book |title=A dictionary of geology and earth sciences |date=2020 |author=Michael Allaby |isbn=978-0-19-187490-1 |edition=Fifth |location=Oxford |oclc=1137380460}}{{page needed|date=March 2026}}</ref> There are four formally defined eons: the [[Hadean]], [[Archean]], [[Proterozoic]] and [[Phanerozoic]].<ref name="ICS" /> | ||
* An '''{{visible anchor|era}}''' is the second largest geochronologic time unit and is equivalent to a chronostratigraphic [[erathem]].<ref name="ICS_chronostrat" /><ref name="dictionary_of_geology_2020" /> There are ten defined eras: the [[Eoarchean]], [[Paleoarchean]], [[Mesoarchean]], [[Neoarchean]], [[Paleoproterozoic]], [[Mesoproterozoic]], [[Neoproterozoic]], [[Paleozoic]], [[Mesozoic]] and [[Cenozoic]], with none from the Hadean eon.<ref name=" | * An '''{{visible anchor|era}}''' is the second largest geochronologic time unit and is equivalent to a chronostratigraphic [[erathem]].<ref name="ICS_chronostrat" /><ref name="dictionary_of_geology_2020" /> There are ten defined eras: the [[Eoarchean]], [[Paleoarchean]], [[Mesoarchean]], [[Neoarchean]], [[Paleoproterozoic]], [[Mesoproterozoic]], [[Neoproterozoic]], [[Paleozoic]], [[Mesozoic]] and [[Cenozoic]], with none from the Hadean eon.<ref name="ICS" /> | ||
* A '''{{visible anchor|period}}''' is equivalent to a chronostratigraphic [[system (stratigraphy)|system]].<ref name="ICS_chronostrat" /><ref name="dictionary_of_geology_2020" /> There are 22 defined periods, with the current being the [[Quaternary]] period.<ref name=" | * A '''{{visible anchor|period}}''' is equivalent to a chronostratigraphic [[system (stratigraphy)|system]].<ref name="ICS_chronostrat" /><ref name="dictionary_of_geology_2020" /> There are 22 defined periods, with the current being the [[Quaternary]] period.<ref name="ICS" /> As an exception, two subperiods are used for the [[Carboniferous|Carboniferous Period]].<ref name="ICS_chronostrat" /> | ||
* An '''{{visible anchor|epoch}}''' is the second smallest geochronologic unit. It is equivalent to a chronostratigraphic [[series (stratigraphy)|series]].<ref name="ICS_chronostrat" /><ref name="dictionary_of_geology_2020" /> There are 37 defined epochs and one informal one. The current epoch is the [[Holocene]]. There are also 11 subepochs which are all within the [[Neogene]] and Quaternary.<ref name=" | * An '''{{visible anchor|epoch}}''' is the second smallest geochronologic unit. It is equivalent to a chronostratigraphic [[series (stratigraphy)|series]].<ref name="ICS_chronostrat" /><ref name="dictionary_of_geology_2020" /> There are 37 defined epochs and one informal one. The current epoch is the [[Holocene]]. There are also 11 subepochs which are all within the [[Neogene]] and Quaternary.<ref name="ICS" /> The use of subepochs as formal units in international chronostratigraphy was ratified in 2022.<ref name="Aubry_2022_subseries">{{cite journal |last1=Aubry |first1=Marie-Pierre |last2=Piller |first2=Werner E. |last3=Gibbard |first3=Philip L. |last4=Harper |first4=David A. T. |last5=Finney |first5=Stanley C. |title=Ratification of subseries/subepochs as formal rank/units in international chronostratigraphy |journal=Episodes |date=March 2022 |volume=45 |issue=1 |pages=97–99 |doi=10.18814/epiiugs/2021/021016 |doi-access=free }}</ref> | ||
* An '''{{visible anchor|age}}''' is the smallest hierarchical geochronologic unit. It is equivalent to a chronostratigraphic [[stage (stratigraphy)|stage]].<ref name="ICS_chronostrat" /><ref name="dictionary_of_geology_2020" /> There are 96 formal and five informal ages.<ref name=" | * An '''{{visible anchor|age}}''' is the smallest hierarchical geochronologic unit. It is equivalent to a chronostratigraphic [[stage (stratigraphy)|stage]].<ref name="ICS_chronostrat" /><ref name="dictionary_of_geology_2020" /> There are 96 formal and five informal ages.<ref name="ICS" /> The current age is the [[Meghalayan]]. | ||
* A ''{{visible anchor|chron}}'' is a non-hierarchical formal geochronology unit of unspecified rank and is equivalent to a chronostratigraphic [[chronozone]].<ref name="ICS_chronostrat" /> These correlate with [[Magnetostratigraphy|magnetostratigraphic]], [[Lithostratigraphy|lithostratigraphic]], or [[Biostratigraphy|biostratigraphic]] units as they are based on previously defined stratigraphic units or geologic features. | * A ''{{visible anchor|chron}}'' is a non-hierarchical formal geochronology unit of unspecified rank and is equivalent to a chronostratigraphic [[chronozone]].<ref name="ICS_chronostrat" /> These correlate with [[Magnetostratigraphy|magnetostratigraphic]], [[Lithostratigraphy|lithostratigraphic]], or [[Biostratigraphy|biostratigraphic]] units as they are based on previously defined stratigraphic units or geologic features. | ||
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The subdivisions {{em|Early}} and {{em|Late}} are used as the geochronologic equivalents of the chronostratigraphic {{em|Lower}} and {{em|Upper}}, e.g., Early [[Triassic]] Period (geochronologic unit) is used in place of Lower Triassic System (chronostratigraphic unit) | The subdivisions {{em|Early}} and {{em|Late}} are used as the geochronologic equivalents of the chronostratigraphic {{em|Lower}} and {{em|Upper}}, e.g., Early [[Triassic]] Period (geochronologic unit) is used in place of Lower Triassic System (chronostratigraphic unit).<ref name="ICS_chronostrat" /> | ||
== Naming of geologic time == | == Naming of geologic time == | ||
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Informally, the time before the Cambrian is often referred to as the [[Precambrian]] or pre-Cambrian (Supereon).<ref name="Shields_2022_pre-Cryogenian" />{{efn|Precambrian or pre-Cambrian is an informal geological term for time before the Cambrian period|name=Precam|group=note}} | Informally, the time before the Cambrian is often referred to as the [[Precambrian]] or pre-Cambrian (Supereon).<ref name="Shields_2022_pre-Cryogenian" />{{efn|Precambrian or pre-Cambrian is an informal geological term for time before the Cambrian period|name=Precam|group=note}} | ||
== History of the geologic time scale == | == History of the geologic time scale == | ||
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=== Early history === | === Early history === | ||
The most modern geological time scale was not formulated until 1911<ref name="Holmes_19113">{{ | The most modern geological time scale was not formulated until 1911<ref name="Holmes_19113">{{cite journal |last1=Holmes |first1=Arthur |title=The association of lead with uranium in rock-minerals, and its application to the measurement of geological time |journal=Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character |date=9 June 1911 |volume=85 |issue=578 |pages=248–256 |doi=10.1098/rspa.1911.0036 |bibcode=1911RSPSA..85..248H |doi-access=free }}</ref> by [[Arthur Holmes]] (1890 – 1965), who drew inspiration from [[James Hutton]] (1726–1797), a Scottish Geologist who presented the idea of uniformitarianism or the theory that changes to the Earth's crust resulted from continuous and uniform processes.<ref>{{Cite web |title=James Hutton {{!}} Father of Modern Geology, Scottish Naturalist |url=https://www.britannica.com/biography/James-Hutton |access-date=2024-12-03 |website=Britannica }}</ref> The broader concept of the relation between rocks and time can be traced back to (at least) the [[philosopher]]s of [[Ancient Greece]] from 1200 BC to 600 AD. [[Xenophanes|Xenophanes of Colophon]] (c. 570–487 [[Common era|BCE]]) observed rock beds with fossils of seashells located above the sea-level, viewed them as once living organisms, and used this to imply an unstable relationship in which the sea had at times [[Marine transgression|transgressed]] over the land and at other times had [[Marine regression|regressed]].<ref name="Fischer_20093">{{cite journal |last1=Fischer |first1=Alfred G. |last2=Garrison |first2=Robert E. |title=The role of the Mediterranean region in the development of sedimentary geology: a historical overview |journal=Sedimentology |date=January 2009 |volume=56 |issue=1 |pages=3–41 |doi=10.1111/j.1365-3091.2008.01009.x }}</ref> This view was shared by a few of Xenophanes's scholars and those that followed, including [[Aristotle]] (384–322 BC) who (with additional observations) reasoned that the positions of land and sea had changed over long periods of time. The concept of [[deep time]] was also recognized by [[History of science and technology in China|Chinese naturalist]] [[Shen Kuo]]<ref name="Nathan 19953">{{Cite book |last=Sivin |first=Nathan |title=Science in ancient China: researches and reflections |date=1995 |publisher=Variorum |isbn=0-86078-492-4 |oclc=956775994}}{{page needed|date=March 2026}}</ref> (1031–1095) and [[Islam]]ic [[scientist]]-philosophers, notably the [[Brethren of Purity|Brothers of Purity]], who wrote on the processes of stratification over the passage of time in their [[Encyclopedia of the Brethren of Purity|treatises]].<ref name="Fischer_20093" /> Their work likely inspired that of the 11th-century [[Persians|Persian]] [[polymath]] [[Avicenna]] (Ibn Sînâ, 980–1037) who wrote in ''[[The Book of Healing]]'' (1027) on the concept of stratification and superposition, pre-dating [[Nicolas Steno]] by more than six centuries.<ref name="Fischer_20093" /> Avicenna also recognized fossils as "petrifications of the bodies of plants and animals",<ref name="Adams_19383">{{cite book |last1=Adams |first1=Frank Dawson |title=The Birth and Development of the Geological Sciences |date=1938 |publisher=William & Wilkins Company |oclc=1484995150 }}{{page needed|date=March 2026}}</ref> with the 13th-century [[Dominican Order|Dominican]] [[bishop]] [[Albertus Magnus]] (c. 1200–1280), who drew from [[Aristotle|Aristotle's]] natural philosophy, extending this into a theory of a petrifying fluid.<ref name="Johnson">{{Cite journal |last1=Johnson |first1=Chris |last2=Bentley |first2=Callan |last3=Panchuk |first3=Karla |last4=Affolter |first4=Matt |last5=Layou |first5=Karen |last6=Jaye |first6=Shelley |last7=Kohrs |first7=Russ |last8=Inkenbrandt |first8=Paul |last9=Mosher |first9=Cam |last10=Ricketts |first10=Brian |last11=Estrada |first11=Charlene |title=Geologic Time and Relative Dating |url=https://open.maricopa.edu/fallglg102/part/sedimentary-rocks-and-environments/ |journal=Maricopa Open Digital Press |language=en}}</ref> These works appeared to have little influence on [[scholar]]s in [[Middle Ages|Medieval Europe]] who looked to the [[Bible]] to explain the origins of fossils and sea-level changes, often attributing these to the '[[Genesis flood narrative|Deluge]]', including [[Restoro d'Arezzo|Ristoro d'Arezzo]] in 1282.<ref name="Fischer_20093" /> It was not until the [[Italian Renaissance]] when [[Leonardo da Vinci]] (1452–1519) would reinvigorate the relationships between stratification, relative sea-level change, and time, denouncing attribution of fossils to the 'Deluge':<ref name="McCurdy_19383">{{Cite book |last=McCurdy |first=Edward |title=The notebooks of Leonardo da Vinci |date=1938 |publisher=Reynal & Hitchcock |location=New York |oclc=2233803 }}{{page needed|date=March 2026}}</ref><ref name="Fischer_20093" /> | ||
{{blockquote|text=Of the stupidity and ignorance of those who imagine that these creatures were carried to such places distant from the sea by the Deluge...Why do we find so many fragments and whole shells between the different layers of stone unless they had been upon the shore and had been covered over by earth newly thrown up by the sea which then became petrified? And if the above-mentioned Deluge had carried them to these places from the sea, you would find the shells at the edge of one layer of rock only, not at the edge of many where may be counted the winters of the years during which the sea multiplied the layers of sand and mud brought down by the | {{blockquote|text=Of the stupidity and ignorance of those who imagine that these creatures were carried to such places distant from the sea by the Deluge...Why do we find so many fragments and whole shells between the different layers of stone unless they had been upon the shore and had been covered over by earth newly thrown up by the sea which then became petrified? And if the above-mentioned Deluge had carried them to these places from the sea, you would find the shells at the edge of one layer of rock only, not at the edge of many where may be counted the winters of the years during which the sea multiplied the layers of sand and mud brought down by the neighbouring rivers and spread them over its shores. And if you wish to say that there must have been many deluges in order to produce these layers and the shells among them it would then become necessary for you to affirm that such a deluge took place every year.}} | ||
[[File:Sketch of the Succession pf Strata and their relative Altitudes.jpg|thumb|Sketch of the Succession of Strata and their Relative Altitudes (William Smith)]] | [[File:Sketch of the Succession pf Strata and their relative Altitudes.jpg|thumb|Sketch of the Succession of Strata and their Relative Altitudes (William Smith)]] | ||
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 creation narrative|Genesis]] were not readily accepted and dissent from [[Religion|religious]] 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.<ref name="Fischer_20093" /> 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."<ref name="Johnson" /> Later, in the 19th century, academics further developed theories on stratification. [[William Smith (geologist)|William Smith]], often referred to as the "Father of Geology"<ref name="earthobservatory.nasa.gov-2008" /> 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 | 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 creation narrative|Genesis]] were not readily accepted and dissent from [[Religion|religious]] 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.<ref name="Fischer_20093" /> 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."<ref name="Johnson" /> Later, in the 19th century, academics further developed theories on stratification. [[William Smith (geologist)|William Smith]], often referred to as the "Father of Geology"<ref name="earthobservatory.nasa.gov-2008" /> 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".<ref name="earthobservatory.nasa.gov-2008">{{Cite web |date=2008-05-08 |title=William Smith (1769-1839) |url=https://earthobservatory.nasa.gov/features/WilliamSmith |access-date=2024-12-02 |website=earthobservatory.nasa.gov |language=en}}</ref> After studying rock layers and the fossils they contained, [[William Smith (geologist)|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.<ref name="Smith-1816">{{cite book |last1=Smith |first1=William |title=Strata identified by organized fossils: Containing prints on colored paper of the most characteristic specimens in each stratum |date=1816 |doi=10.5962/bhl.title.106808 }}{{page needed|date=March 2026}}</ref> 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."<ref name="Smith-1816" /> | ||
=== Establishment of primary principles === | === Establishment of primary principles === | ||
Niels Stensen, more commonly known as Nicolas Steno (1638–1686), is credited with establishing four of the guiding principles of stratigraphy.<ref name="Fischer_20093"/> In ''De solido intra solidum naturaliter contento dissertationis prodromus'' Steno states:<ref name="Steno_1669">{{Cite book |last=Steno |first=Nicolaus |url=https://books.google.com/books?id=xz28AAAAIAAJ |title=Nicolai Stenonis de solido intra solidvm natvraliter contento dissertationis prodromvs ad serenissimvm Ferdinandvm II ... |date=1669 |publisher=W. Junk |language=la}}</ref><ref name="Kardel_2018">{{ | Niels Stensen, more commonly known as Nicolas Steno (1638–1686), is credited with establishing four of the guiding principles of stratigraphy.<ref name="Fischer_20093"/> In ''De solido intra solidum naturaliter contento dissertationis prodromus'' Steno states:<ref name="Steno_1669">{{Cite book |last=Steno |first=Nicolaus |url=https://books.google.com/books?id=xz28AAAAIAAJ |title=Nicolai Stenonis de solido intra solidvm natvraliter contento dissertationis prodromvs ad serenissimvm Ferdinandvm II ... |date=1669 |publisher=W. Junk |language=la}}</ref><ref name="Kardel_2018">{{cite book |last1=Kardel |first1=Troels |last2=Maquet |first2=Paul |title=Nicolaus Steno |chapter=2.27 the Prodromus to a Dissertation on a Solid Naturally Contained within a Solid |date=2018 |pages=763–825 |doi=10.1007/978-3-662-55047-2_38 |isbn=978-3-662-55046-5 }}</ref> | ||
<blockquote> | <blockquote> | ||
* 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. | * 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. | ||
| Line 509: | Line 112: | ||
=== Formulation of a modern geologic time scale === | === Formulation of a modern geologic time scale === | ||
The apparent, earliest formal division of the geologic record with respect to time was introduced during the era of Biblical models by [[Thomas Burnet (theologian)|Thomas Burnet]] who applied a two-fold terminology to mountains by identifying "''montes primarii''" for rock formed at the time of the 'Deluge', and younger "''monticulos secundarios"'' formed later from the debris of the "''primarii"''.<ref name="Burnet_1681">{{Cite book |last=Burnet |first=Thomas |title=Telluris Theoria Sacra: orbis nostri originen et mutationes generales, quasi am subiit aut olim subiturus est, complectens. Libri duo priores de Diluvio & Paradiso |publisher=G. Kettiby |year=1681 |location=London |language=la}}</ref><ref name="Fischer_20093"/> [[Anton Moro]] (1687–1784) also used primary and secondary divisions for rock units but his mechanism was volcanic.<ref name="Moro_1740">{{Cite book |last=Moro |first=Anton Lazzaro |url=https://books.google.com/books?id=03RBAAAAYAAJ |title=De'crostacei e degli altri marini corpi che si truovano su'monti |date=1740 |publisher=Appresso Stefano Monti |language=it}}</ref><ref name="Fischer_20093"/> In this early version of the [[Plutonism]] theory, the interior of Earth was seen as hot, and this drove the creation of primary igneous and metamorphic rocks and secondary rocks formed contorted and fossiliferous sediments. These primary and secondary divisions were expanded on by [[Giovanni Targioni Tozzetti]] (1712–1783) and [[Giovanni Arduino (geologist)|Giovanni Arduino]] (1713–1795) to include tertiary and quaternary divisions.<ref name="Fischer_20093"/> These divisions were used to describe both the time during which the rocks were laid down, and the collection of rocks themselves (i.e., it was correct to say Tertiary rocks, and Tertiary Period). Only the Quaternary division is retained in the modern geologic time scale, while the Tertiary division was in use until the early 21st century. The Neptunism and Plutonism theories would compete into the early [[19th century]] with a key driver for resolution of this debate being the work of [[James Hutton]] (1726–1797), in particular his ''[[Theory of the Earth]]'', first presented before the [[Royal Society of Edinburgh]] in 1785.<ref name="Hutton_1788">{{ | The apparent, earliest formal division of the geologic record with respect to time was introduced during the era of Biblical models by [[Thomas Burnet (theologian)|Thomas Burnet]] who applied a two-fold terminology to mountains by identifying "''montes primarii''" for rock formed at the time of the 'Deluge', and younger "''monticulos secundarios"'' formed later from the debris of the "''primarii"''.<ref name="Burnet_1681">{{Cite book |last=Burnet |first=Thomas |title=Telluris Theoria Sacra: orbis nostri originen et mutationes generales, quasi am subiit aut olim subiturus est, complectens. Libri duo priores de Diluvio & Paradiso |publisher=G. Kettiby |year=1681 |location=London |language=la}}</ref><ref name="Fischer_20093"/> [[Anton Moro]] (1687–1784) also used primary and secondary divisions for rock units but his mechanism was volcanic.<ref name="Moro_1740">{{Cite book |last=Moro |first=Anton Lazzaro |url=https://books.google.com/books?id=03RBAAAAYAAJ |title=De'crostacei e degli altri marini corpi che si truovano su'monti |date=1740 |publisher=Appresso Stefano Monti |language=it}}</ref><ref name="Fischer_20093"/> In this early version of the [[Plutonism]] theory, the interior of Earth was seen as hot, and this drove the creation of primary igneous and metamorphic rocks and secondary rocks formed contorted and fossiliferous sediments. These primary and secondary divisions were expanded on by [[Giovanni Targioni Tozzetti]] (1712–1783) and [[Giovanni Arduino (geologist)|Giovanni Arduino]] (1713–1795) to include tertiary and quaternary divisions.<ref name="Fischer_20093"/> These divisions were used to describe both the time during which the rocks were laid down, and the collection of rocks themselves (i.e., it was correct to say Tertiary rocks, and Tertiary Period). Only the Quaternary division is retained in the modern geologic time scale, while the Tertiary division was in use until the early 21st century. The Neptunism and Plutonism theories would compete into the early [[19th century]] with a key driver for resolution of this debate being the work of [[James Hutton]] (1726–1797), in particular his ''[[Theory of the Earth]]'', first presented before the [[Royal Society of Edinburgh]] in 1785.<ref name="Hutton_1788">{{cite journal |last1=Hutton |first1=James |title=X. Theory of the Earth; or an Investigation of the Laws observable in the Composition, Dissolution, and Restoration of Land upon the Globe |journal=Transactions of the Royal Society of Edinburgh |date=1788 |volume=1 |issue=2 |pages=209–304 |doi=10.1017/S0080456800029227 }}</ref><ref name="Hutton_1795v1">{{Cite book |last=Hutton |first=James |url=https://www.gutenberg.org/ebooks/12861 |title=Theory of the Earth |year=1795 |volume=1 |location=Edinburgh}}</ref><ref name="Hutton_1795v2">{{Cite book |last=Hutton |first=James |url=https://www.gutenberg.org/ebooks/14179 |title=Theory of the Earth |year=1795 |volume=2 |location=Edinburgh}}</ref> Hutton's theory would later become known as [[uniformitarianism]], popularised by [[John Playfair]]<ref name="Playfair_1802">{{Cite book |last=Playfair |first=John |url=http://archive.org/details/NHM104643 |title=Illustrations of the Huttonian theory of the earth |date=1802 |publisher=Neill & Co |others=Digitised by London Natural History Museum Library |location=Edinburgh}}</ref> (1748–1819) and later [[Charles Lyell]] (1797–1875) in his ''[[Principles of Geology]]''.<ref name="Lyell_1832v1">{{Cite book |last=Lyell |first=Sir Charles |url=https://books.google.com/books?id=mmIOAAAAQAAJ |title=Principles of Geology: Being an Attempt to Explain the Former Changes of the Earth's Surface, by Reference to Causes Now in Operation |date=1832 |publisher=John Murray |volume=1 |location=London |language=en}}</ref><ref name="Lyell_1832v2">{{Cite book |last=Lyell |first=Sir Charles |url=https://books.google.com/books?id=TlwPAAAAYAAJ |title=Principles of Geology: Being an Attempt to Explain the Former Changes of the Earth's Surface, by Reference to Causes Now in Operation |date=1832 |publisher=John Murray |volume=2 |location=London |language=en}}</ref><ref name="Lyell_1834v3">{{Cite book |last=Lyell |first=Sir Charles |url=https://books.google.com/books?id=UrIJAAAAIAAJ |title=Principles of Geology: Being an Inquiry how for the Former Changes of the Earth's Surface are Referrable to Causes Now in Operation |date=1834 |publisher=John Murray |volume=3 |location=London |language=en}}</ref> Their theories strongly contested the 6,000 year age of the Earth as suggested determined by [[James Ussher]] via Biblical chronology that was accepted at the time by western religion. Instead, using geological evidence, they contested Earth to be much older, cementing the concept of deep time. | ||
During the early 19th century [[William Smith (geologist)|William Smith]], [[Georges Cuvier]], [[Jean Baptiste Julien d'Omalius d'Halloy|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. | During the early 19th century [[William Smith (geologist)|William Smith]], [[Georges Cuvier]], [[Jean Baptiste Julien d'Omalius d'Halloy|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 advent of geochronometry === | === The advent of geochronometry === | ||
[[File:Pierre Lecomte du Noüy - LES AGES DE LA VIE SUR LA TERRE - in L'Homme et sa destinée - 1947.jpg|thumb|One example of an obsolete geological time scale (France, mid-1940s).]] | |||
During the 19th century, the debate regarding Earth's age was renewed, with geologists estimating ages based on [[denudation]] rates and sedimentary thicknesses or ocean chemistry, and physicists determining ages for the cooling of the Earth or the Sun using basic [[thermodynamics]] or orbital physics.<ref name="Dalrymple 2001 AoE" /> These estimations varied from 15,000 million years to 0.075 million years depending on method and author, but the estimations of [[William Thomson, 1st Baron Kelvin|Lord Kelvin]] and [[Clarence King]] were held in high regard at the time due to their pre-eminence in physics and geology. All of these early geochronometric determinations would later prove to be incorrect. | During the 19th century, the debate regarding Earth's age was renewed, with geologists estimating ages based on [[denudation]] rates and sedimentary thicknesses or ocean chemistry, and physicists determining ages for the cooling of the Earth or the Sun using basic [[thermodynamics]] or orbital physics.<ref name="Dalrymple 2001 AoE" /> These estimations varied from 15,000 million years to 0.075 million years depending on method and author, but the estimations of [[William Thomson, 1st Baron Kelvin|Lord Kelvin]] and [[Clarence King]] were held in high regard at the time due to their pre-eminence in physics and geology. All of these early geochronometric determinations would later prove to be incorrect. | ||
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.<ref name="Dalrymple 2001 AoE" /> Early attempts at determining ages of uranium minerals and rocks by [[Ernest Rutherford]], [[Bertram Boltwood]], [[Robert Strutt, 4th Baron Rayleigh|Robert Strutt]], and Arthur Holmes, would culminate in what are considered the first international geological time scales by Holmes in 1911 and 1913.<ref name="Holmes_19113"/><ref name="Holmes 1913">{{Cite book |last=Holmes |first=Arthur |url=http://archive.org/details/ageofearth00holmuoft |title=The age of the earth |date=1913 |publisher=London, Harper |others=Gerstein - University of Toronto}}</ref><ref name="Lewis_2001">{{ | 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.<ref name="Dalrymple 2001 AoE" /> Early attempts at determining ages of uranium minerals and rocks by [[Ernest Rutherford]], [[Bertram Boltwood]], [[Robert Strutt, 4th Baron Rayleigh|Robert Strutt]], and Arthur Holmes, would culminate in what are considered the first international geological time scales by Holmes in 1911 and 1913.<ref name="Holmes_19113"/><ref name="Holmes 1913">{{Cite book |last=Holmes |first=Arthur |url=http://archive.org/details/ageofearth00holmuoft |title=The age of the earth |date=1913 |publisher=London, Harper |others=Gerstein - University of Toronto}}</ref><ref name="Lewis_2001">{{cite journal |last1=Lewis |first1=Cherry L. E. |title=Arthur Holmes' vision of a geological timescale |journal=Geological Society, London, Special Publications |date=January 2001 |volume=190 |issue=1 |pages=121–138 |doi=10.1144/GSL.SP.2001.190.01.10 |bibcode=2001GSLSP.190..121L }}</ref> The discovery of [[isotope]]s in 1913<ref>{{cite journal |last1=Soddy |first1=Frederick |title=Intra-atomic Charge |journal=Nature |date=4 December 1913 |volume=92 |issue=2301 |pages=399–400 |doi=10.1038/092399c0 |bibcode=1913Natur..92..399S }}</ref> 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.<ref name="Dalrymple 2001 AoE" /><ref name="Lewis_2001" /><ref name="Holmes_1960">{{cite journal |last1=Holmes |first1=A. |title=A revised geological time-scale |journal=Transactions of the Edinburgh Geological Society |date=January 1959 |volume=17 |issue=3 |pages=183–216 |doi=10.1144/transed.17.3.183 }}</ref><ref name="GTS1960">{{cite journal |title=A Revised Geological Time-Scale |journal=Nature |date=July 1960 |volume=187 |issue=4731 |pages=27–28 |doi=10.1038/187027d0 |bibcode=1960Natur.187T..27. |doi-access=free }}</ref> | ||
=== Modern international geological time scale === | === Modern international geological time scale === | ||
The establishment of the IUGS in 1961<ref name="Harrison_1978">{{ | The establishment of the IUGS in 1961<ref name="Harrison_1978">{{cite journal |last1=Harrison |first1=James M. |title=The Roots of IUGS |journal=Episodes |date=March 1978 |volume=1 |issue=1 |pages=20–23 |doi=10.18814/epiiugs/1978/v1i1/005 |doi-access=free }}</ref> and acceptance of the Commission on Stratigraphy (applied in 1965)<ref name="ICS_statutes_1986">{{Cite book |author=International Union of Geological Sciences. Commission on Stratigraphy |title=Guidelines and statutes of the International Commission on Stratigraphy (ICS) |date=1986 |publisher=Herausgegeben von der Senckenbergischen Naturforschenden Gesellschaft |others=J. W. Cowie |isbn=3-924500-19-3 |location=Frankfurt a.M. |oclc=14352783}}{{page needed|date=March 2026}}</ref> to become a member commission of IUGS led to the founding of the ICS. One of the primary objectives of the ICS is "the establishment, publication and revision of the ICS International Chronostratigraphic Chart which is the standard, reference global Geological Time Scale to include the ratified Commission decisions".<ref name="ICS_statutes" /> | ||
Following on from Holmes, several ''A Geological Time Scale'' books were published in 1982,<ref name="GTS82">{{Cite book |title=A geologic time scale |date=1982 |publisher=Cambridge University Press |author=W. B. Harland |isbn=0-521-24728-4 |location=Cambridge [England] |oclc=8387993}}</ref> 1989,<ref name="GTS1989">{{Cite book |title=A geologic time scale 1989 |date=1990 |publisher=Cambridge University Press |author=W. B. Harland |isbn=0-521-38361-7 |location=Cambridge |oclc=20930970}}</ref> 2004,<ref name="GTS2004">{{Cite book |title=A geologic time scale 2004 |date=2004 |publisher=Cambridge University Press |author1=F. M. Gradstein |author2=James G. Ogg |author3=A. Gilbert Smith |isbn=0-511-08201-0 |location=Cambridge, UK |oclc=60770922}}</ref> 2008,<ref name="GTS2008">{{ | Following on from Holmes, several ''A Geological Time Scale'' books were published in 1982,<ref name="GTS82">{{Cite book |title=A geologic time scale |date=1982 |publisher=Cambridge University Press |author=W. B. Harland |isbn=0-521-24728-4 |location=Cambridge [England] |oclc=8387993}}</ref> 1989,<ref name="GTS1989">{{Cite book |title=A geologic time scale 1989 |date=1990 |publisher=Cambridge University Press |author=W. B. Harland |isbn=0-521-38361-7 |location=Cambridge |oclc=20930970}}</ref> 2004,<ref name="GTS2004">{{Cite book |title=A geologic time scale 2004 |date=2004 |publisher=Cambridge University Press |author1=F. M. Gradstein |author2=James G. Ogg |author3=A. Gilbert Smith |isbn=0-511-08201-0 |location=Cambridge, UK |oclc=60770922}}</ref> 2008,<ref name="GTS2008">{{cite journal |last1=Gradstein |first1=Felix M. |last2=Ogg |first2=James G. |last3=van Kranendonk |first3=Martin |title=On the Geologic Time Scale 2008 |journal=Newsletters on Stratigraphy |date=23 July 2008 |volume=43 |issue=1 |pages=5–13 |doi=10.1127/0078-0421/2008/0043-0005 |bibcode=2008NewSt..43....5G }}</ref> 2012,<ref name="GTS2012">{{Cite book |title=The geologic time scale 2012. Volume 2 |date=2012 |publisher=Elsevier |author=F. M. Gradstein |isbn=978-0-444-59448-8 |edition=1st |location=Amsterdam |oclc=808340848}}</ref> 2016,<ref name="GTS2016">{{Cite book |last=Ogg |first=James G. |title=A concise geologic time scale 2016 |date=2016 |publisher=Elsevier |others=Gabi Ogg, F. M. Gradstein |isbn=978-0-444-59468-6 |location=Amsterdam, Netherlands |oclc=949988705}}</ref> and 2020.<ref name="GTS2020">{{Cite book |title=Geologic time scale 2020 |date=2020 |author1=F. M. Gradstein |author2=James G. Ogg |author3=Mark D. Schmitz |author4=Gabi Ogg |isbn=978-0-12-824361-9 |location=Amsterdam, Netherlands |oclc=1224105111}}</ref> 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.<ref name="ICS" /> Subsequent ''Geologic Time Scale'' books (2016<ref name="GTS2016" /> and 2020<ref name="GTS2020"/>) 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. | ||
{{Timeline geological timescale}} | {{Timeline geological timescale}} | ||
== | == Table of geologic time == | ||
The following table summarises the major events and characteristics of the divisions making up the geologic time scale of Earth. This table is arranged with the most recent geologic periods at the top, and the oldest at the bottom. The height of each table entry does not correspond to the duration of each subdivision of time. As such, this table is not to scale and does not accurately represent the relative time-spans of each geochronologic unit. While the [[Phanerozoic]] Eon looks longer than the rest, it merely spans ~538.8 Ma (~11.8% of Earth's history), whilst the previous three eons{{Efn|name=Precam|group=note}} collectively span ~4,028.2 Ma (~88.2% of Earth's history). This bias toward the most recent eon is in part due to the relative lack of information about events that occurred during the first three eons compared to the current eon (the Phanerozoic).<ref name="Shields_2022_pre-Cryogenian" /><ref>{{cite web |title=Geological time scale |url=https://www.digitalatlasofancientlife.org/learn/geological-time/geological-time-scale/ |access-date=January 17, 2022 |work=Digital Atlas of Ancient Life |publisher=Paleontological Research Institution}}</ref> The use of subseries/subepochs has been ratified by the ICS.<ref name ="Aubry_2022_subseries"/> | |||
While some regional terms are still in use,<ref name="GTS2012_Precambrian" /> 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.<ref name="ICS_statutes" /><ref name="ICS_IGTS">{{cite web |title=International Commission on Stratigraphy |url=https://stratigraphy.org/ |access-date=5 June 2022 |work=International Geological Time Scale}}</ref> | |||
While some regional terms are still in use,<ref name="GTS2012_Precambrian" /> 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.<ref name="ICS_statutes" /><ref name="ICS_IGTS">{{cite web |title=International Commission on Stratigraphy |url=https://stratigraphy.org/ | | |||
{{sticky header}} | {{sticky header}} | ||
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|- | |- | ||
| rowspan="102" style="background:{{period color|Phanerozoic}}" |[[Phanerozoic]] | | rowspan="102" style="background:{{period color|Phanerozoic}}" |[[Phanerozoic]] | ||
| rowspan="24" style="background:{{period color|Cenozoic}}" |[[Cenozoic]]<br/>{{efn|name=Tertiary|group=note}} | | rowspan="24" style="background:{{period color|Cenozoic}}" |[[Cenozoic]]<br/>{{efn|The Tertiary is a now obsolete geologic system/period spanning from 66 Ma to 2.6 Ma. It has no exact equivalent in the modern ICC, but is approximately equivalent to the merged Palaeogene and Neogene systems/periods.<ref name="Head_etal_2008">{{cite journal |last1=Head |first1=Martin J. |last2=Gibbard |first2=Philip |last3=Salvador |first3=Amos |title=The Quaternary: its character and definition |journal=Episodes |date=June 2008 |volume=31 |issue=2 |pages=234–238 |doi=10.18814/epiiugs/2008/v31i2/009 |bibcode=2008Episo..31..234H |doi-access=free }}</ref><ref name ="Gibbard_etal_2010">{{cite journal |last1=Gibbard |first1=Philip L. |last2=Head |first2=Martin J. |last3=Walker |first3=Michael J. C. |title=Formal ratification of the Quaternary System/Period and the Pleistocene Series/Epoch with a base at 2.58 Ma |journal=Journal of Quaternary Science |date=February 2010 |volume=25 |issue=2 |pages=96–102 |doi=10.1002/jqs.1338 |bibcode=2010JQS....25...96G }}</ref>|name=Tertiary|group=note}} | ||
| rowspan="7" style="background:{{period color|Quaternary}}" |[[Quaternary]] | | rowspan="7" style="background:{{period color|Quaternary}}" |[[Quaternary]] | ||
| rowspan="3" style="background:{{period color|Holocene}}" |[[Holocene]] | | rowspan="3" style="background:{{period color|Holocene}}" |[[Holocene]] | ||
| style="background:#fcf0f2" |[[Meghalayan]] | | style="background:#fcf0f2" |[[Meghalayan]] | ||
|[[4.2-kiloyear event]], [[ | |[[4.2-kiloyear event|4.2 ka cool period]], dry climate leads to decline of agriculture-related civilisations in [[Ancient Egypt|Egypt]], [[Mesopotamia]] and [[History of India|India]].<ref>{{cite journal |last1=Ran |first1=Min |last2=Chen |first2=Liang |title=The 4.2 ka BP climatic event and its cultural responses |journal=Quaternary International |date=June 2019 |volume=521 |pages=158–167 |doi=10.1016/j.quaint.2019.05.030 }}</ref> [[Medieval Warm Period]] (about 900 - 1350 CE) and [[Little Ice Age]] (about 1400 to 1900 CE).<ref name=":2">{{cite journal |last1=Pratap |first1=Shailendra |last2=Markonis |first2=Yannis |title=The response of the hydrological cycle to temperature changes in recent and distant climatic history |journal=Progress in Earth and Planetary Science |date=31 May 2022 |volume=9 |issue=1 |article-number=30 |doi=10.1186/s40645-022-00489-0 |doi-access=free }}</ref> Rapidly warming climate as [[Carbon dioxide|CO<sub>2</sub>]] added to atmosphere from burning [[fossil fuel]]s.<ref name="Scotese et al 2021" /> | ||
| style="background:#fcf0f2" |{{Period start|meghalayan}} {{Period start error|meghalayan}}<sup>*</sup> | | style="background:#fcf0f2" |{{Period start|meghalayan}} {{Period start error|meghalayan}}<sup>*</sup> | ||
|- | |- | ||
| style="background:#fcf0e8" |[[Northgrippian]] | | style="background:#fcf0e8" |[[Northgrippian]] | ||
|[[8.2-kiloyear event]], | |[[8.2-kiloyear event|8.2 ka cool period]],<ref name=":2" /> followed by warming climate with melting ice raising sea levels.<ref name=":1" /> [[Doggerland]] and [[Sundaland]] flooded.<ref>{{cite journal |last1=Cotterill |first1=Carol J. |last2=Phillips |first2=Emrys |last3=James |first3=Leo |last4=Forsberg |first4=Carl Fredrik |last5=Tjelta |first5=Tor Inge |last6=Carter |first6=Gareth |last7=Dove |first7=Dayton |title=The evolution of the Dogger Bank, North Sea: A complex history of terrestrial, glacial and marine environmental change |journal=Quaternary Science Reviews |date=September 2017 |volume=171 |pages=136–153 |doi=10.1016/j.quascirev.2017.07.006 }}</ref><ref>{{cite journal |last1=Solihuddin |first1=Tubagus |title=A Drowning Sunda Shelf Model during Last Glacial Maximum (LGM) and Holocene: A Review |journal=Indonesian Journal on Geoscience |date=31 August 2014 |volume=1 |issue=2 |pages=99–107 |doi=10.17014/ijog.1.2.99-107 }}</ref> | ||
| style="background:#fcf0e8" |{{Period start|northgrippian}} {{Period start error|northgrippian}}<sup>*</sup> | | style="background:#fcf0e8" |{{Period start|northgrippian}} {{Period start error|northgrippian}}<sup>*</sup> | ||
|- | |- | ||
| style="background:#fcf0de" |[[Greenlandian]] | | style="background:#fcf0de" |[[Greenlandian]] | ||
| | |[[Younger Dryas]] and [[Last Glacial Period]] end. Rise of agriculture.<ref name=":1" /> Extinction of [[Late Pleistocene extinctions|Pleistocene megafauna]].<ref name=":8" /> | ||
| style="background:#fcf0de" |{{Period start|greenlandian}} {{Period start error|greenlandian}}<sup>*</sup> | | style="background:#fcf0de" |{{Period start|greenlandian}} {{Period start error|greenlandian}}<sup>*</sup> | ||
|- | |- | ||
| rowspan="4" style="background:{{period color|Pleistocene}}" |[[Pleistocene]] | | rowspan="4" style="background:{{period color|Pleistocene}}" |[[Pleistocene]] | ||
| style="background:{{period color|Upper Pleistocene}}" |[[Late Pleistocene|Upper/Late]] ''('[[Tarantian]]')'' | | style="background:{{period color|Upper Pleistocene}}" |[[Late Pleistocene|Upper/Late]] ''('[[Tarantian]]')'' | ||
|[[Eemian]] [[ | |[[Last Interglacial|Eemian Interglacial Stage]] followed by the Last Glacial Period.<ref name=":2" /> After [[Last Glacial Maximum]] (about 25 – 15 ka) climate begins to warm. Younger Dryas final cold period of ice age. [[Youngest Toba eruption|Toba supervolcano]] eruption. ''[[Human|Homo sapiens]]'' spread across the globe. ''[[Homo floresiensis]]'' live on island of [[Flores]]. ''[[Neanderthal|Homo neanderthalensis]]'' go extinct.<ref name=":8" /> | ||
| style="background:{{period color|upper Pleistocene}}" |{{Period start|Late pleistocene}} {{Period start error|Late pleistocene}} | | style="background:{{period color|upper Pleistocene}}" |{{Period start|Late pleistocene}} {{Period start error|Late pleistocene}} | ||
|- | |- | ||
| style="background:{{period color|Middle Pleistocene}}" |[[Chibanian]] | | style="background:{{period color|Middle Pleistocene}}" |[[Chibanian]] | ||
|[[ | |[[Brunhes–Matuyama reversal|Brunhes–Matuyama geomagnetic reversal event]].<ref name=":11">{{cite book |last1=Ehlers |first1=J. |last2=Gibbard |first2=P.L. |last3=Hughes |first3=P.D. |title=Past Glacial Environments |chapter=Quaternary Glaciations and Chronology |date=2018 |pages=77–101 |doi=10.1016/B978-0-08-100524-8.00003-8 |isbn=978-0-08-100524-8 }}</ref> ''[[Homo heidelbergensis]]'' evolves in Africa and spreads to Europe. ''Homo neanderthalensis'' appear in western [[Eurasia]]. ''Homo sapiens'' evolve in Africa. ''[[Homo erectus]]'' and ''Homo heidelbergensis'' die out.<ref name=":8" /> | ||
| style="background:{{period color|Middle Pleistocene}}" |{{Period start|middle pleistocene}}{{Period start error|middle pleistocene}}<sup>*</sup> | | style="background:{{period color|Middle Pleistocene}}" |{{Period start|middle pleistocene}}{{Period start error|middle pleistocene}}<sup>*</sup> | ||
|- | |- | ||
| style="background:{{period color|Calabrian}}" |[[Early Pleistocene|Calabrian]] | | style="background:{{period color|Calabrian}}" |[[Early Pleistocene|Calabrian]] | ||
| | |[[Mid-Pleistocene Transition|Mid Pleistocene transition]]: [[Glacial period|glacial]]/[[interglacial]] frequency slows to every 100,000 years. Glacial periods now long enough for continental [[ice-sheet]]s beyond polar regions.<ref name="Scotese et al 2021" /><ref name=":11" /> [[Chimpanzee]]s and [[bonobo]]s diverge. ''Homo erectus'' spreads through Eurasia. ''[[Homo habilis]] goes extinct''.<ref name=":8" /> | ||
| style="background:{{period color|Calabrian}}" |{{Period start|calabrian}} {{Period start error|calabrian}}<sup>*</sup> | | style="background:{{period color|Calabrian}}" |{{Period start|calabrian}} {{Period start error|calabrian}}<sup>*</sup> | ||
|- | |- | ||
| style="background:{{period color|Gelasian}}" |[[Gelasian]] | | style="background:{{period color|Gelasian}}" |[[Gelasian]] | ||
|Start of [[Quaternary glaciation]] | |Start of [[Quaternary glaciation|Pleistocene Ice Age]]: 40,000 year cycles of glacials/interglacials with [[ice cap]] growth and retreat, and sea level falls and rises.<ref name="Scotese et al 2021" /> Rise of Pleistocene megafauna. ''Homo habilis'' and ''Homo erectus'' evolve in Africa.<ref name=":8" /> | ||
| style="background:{{period color|Gelasian}}" |{{Period start|gelasian}} {{Period start error|geliasian}}<sup>*</sup> | | style="background:{{period color|Gelasian}}" |{{Period start|gelasian}} {{Period start error|geliasian}}<sup>*</sup> | ||
|- | |- | ||
| Line 886: | Line 181: | ||
| rowspan="2" style="background:{{period color|Pliocene}}" |[[Pliocene]] | | rowspan="2" style="background:{{period color|Pliocene}}" |[[Pliocene]] | ||
| style="background:{{period color|Piacenzian}}" |[[Piacenzian]] | | style="background:{{period color|Piacenzian}}" |[[Piacenzian]] | ||
|[[ | |[[Isthmus of Panama]] land bridge forms between North and South America blocking equatorial ocean currents between Atlantic and Pacific oceans. [[Gulf Stream]] develops as Atlantic waters divert northward.<ref name="Torsvik_Cocks 2017" /><ref name="Scotese et al 2021" /> Global temperatures warm melting polar [[ice cap]]s and sea levels rise flooding [[continental margin]]s. Temperatures drop at 2.7 Ma and the [[Quaternary glaciation|Pleistocene Ice Age]] begins.<ref name="Scotese et al 2021" /> First modern [[big cat]]s and modern [[horse]]s. [[Tortoise]]s and [[Tanager|finch-billed tanagers]] arrive in the [[Galápagos Islands|Galapagos]].<ref name=":8" /> Earliest [[human]]s appear.<ref name=":1" /> | ||
| style="background:{{period color|Piacenzian}}" |{{Period start|piacenzian}} {{Period start error|piacenzian}}<sup>*</sup> | | style="background:{{period color|Piacenzian}}" |{{Period start|piacenzian}} {{Period start error|piacenzian}}<sup>*</sup> | ||
|- | |- | ||
| style="background:{{period color|Zanclean}}" |[[Zanclean]] | | style="background:{{period color|Zanclean}}" |[[Zanclean]] | ||
|[[ | |[[Strait of Gibraltar|Straits of Gibraltar]] form as Atlantic waters flood the [[Mediterranean Sea]] basin ([[Zanclean flood]]).<ref name="Torsvik_Cocks 2017" /> Global climate continues to cool.<ref name="Scotese et al 2021" /> [[Asian elephant]]s appear.<ref name=":8" /> [[Hominini|Hominins]] ''[[Ardipithecus]]'', ''[[Australopithecus]]'' and ''[[Paranthropus]]'' evolve.<ref name=":1" /> | ||
| style="background:{{period color|Zanclean}}" |{{Period start|zanclean}} {{Period start error|zanclean}}<sup>*</sup> | | style="background:{{period color|Zanclean}}" |{{Period start|zanclean}} {{Period start error|zanclean}}<sup>*</sup> | ||
|- | |- | ||
| rowspan="6" style="background:{{period color|Miocene}}" |[[Miocene]] | | rowspan="6" style="background:{{period color|Miocene}}" |[[Miocene]] | ||
| style="background:{{period color|Messinian}}" |[[Messinian]] | | style="background:{{period color|Messinian}}" |[[Messinian]] | ||
| rowspan="2" |[[Messinian | | rowspan="2" |Connection between Mediterranean Sea and Atlantic is blocked, resulting in [[Messinian salinity crisis]] with [[evaporite]]s accumulating across Mediterranean as its waters dry up. Collision of [[Banda Arc]] with Australia and Timor begins.<ref name="Torsvik_Cocks 2017" /> Global climate cools and permanent ice cap forms in Arctic. Sea levels drop as [[ice sheet]]s grow.<ref name="Scotese et al 2021" /> Spread of [[C4 carbon fixation|C4 grasses]] result in extinction of many [[herbivores]].<ref name=":1" /> [[Sea snake]]s evolve. [[Gorilla]]-human-[[chimpanzee]] lineages split, then chimpanzees and humans diverge.<ref name=":8" /> Earliest hominid ''[[Sahelanthropus]]''.<ref name=":1" /> | ||
| style="background:{{period color|Messinian}}" |{{Period start|messinian}} {{Period start error|messinian}}<sup>*</sup> | | style="background:{{period color|Messinian}}" |{{Period start|messinian}} {{Period start error|messinian}}<sup>*</sup> | ||
|- | |- | ||
| Line 902: | Line 197: | ||
|- | |- | ||
| style="background:{{period color|Serravallian}}" |[[Serravallian]] | | style="background:{{period color|Serravallian}}" |[[Serravallian]] | ||
| rowspan="2" | | | rowspan="2" |Australia begins to collide with Southeast Asia, blocking equatorial circulation between western Pacific and Indian Oceans.<ref name="Torsvik_Cocks 2017" /><ref name="Scotese et al 2021" /> Antarctic ice cap shrinks as global temperatures warm ([[Middle Miocene Climatic Optimum|Middle Miocene climatic optimum]]).<ref name="Scotese et al 2021" /> Last [[Creodonta|creodont]]s (early [[Predation|predatory]] mammals) become extinct. ''[[Megalodon]]'' (giant shark) evolves.<ref name=":8" /> | ||
| style="background:{{period color|Serravallian}}" |{{Period start|serravallian}} {{Period start error|serravallian}}<sup>*</sup> | | style="background:{{period color|Serravallian}}" |{{Period start|serravallian}} {{Period start error|serravallian}}<sup>*</sup> | ||
|- | |- | ||
| Line 909: | Line 204: | ||
|- | |- | ||
| style="background:{{period color|Burdigalian}}" |[[Burdigalian]] | | style="background:{{period color|Burdigalian}}" |[[Burdigalian]] | ||
| rowspan="2" |[[ | | rowspan="2" |The [[Tian Shan]] and [[Altai mountains]], Central Asia, form ([[Geology of the Himalayas|Himalayan orogeny]]). [[Columbia River Basalt Group|Columbia River Basalt]] [[large igneous province]] (LIP) eruptions above rising [[Yellowstone hotspot]], North America.<ref name="Torsvik_Cocks 2017" /><ref name=":1" /> Climate continues to cool.<ref name="Scotese et al 2021" /> [[Asteraceae|Compositae]] ([[herbaceous plant]]s) appear and rapidly diversify, triggering [[evolutionary radiation]]s in [[rodent]]s, [[snake]]s (first [[viper]]s appear) and [[songbird]]s.<ref name=":1" /><ref name=":8" /> First [[gibbon]]s and [[orangutan]]s. First modern [[dolphin]]s.<ref name=":8" /> | ||
| style="background:{{period color|Burdigalian}}" |{{Period start|burdigalian}} {{Period start error|burdigalian}} | | style="background:{{period color|Burdigalian}}" |{{Period start|burdigalian}} {{Period start error|burdigalian}} | ||
|- | |- | ||
| Line 918: | Line 213: | ||
| rowspan="2" style="background:{{period color|Oligocene}}" |[[Oligocene]] | | rowspan="2" style="background:{{period color|Oligocene}}" |[[Oligocene]] | ||
| style="background:{{period color|Chattian}}" |[[Chattian]] | | style="background:{{period color|Chattian}}" |[[Chattian]] | ||
| rowspan="2" |[[ | | rowspan="2" |North America and [[Eurasia]] [[Plate tectonics|plate boundary]] established along [[Mid-Atlantic Ridge]].<ref name="Torsvik_Cocks 2017" /> Central American [[volcanic arc]] begins to collide with South America. [[Ethiopia-Yemen Continental Flood Basalts|East African]] LIP eruptions begin as [[Afar triple junction|Afar mantle plume]] rises.<ref name="Torsvik_Cocks 2017" /> [[Late Cenozoic Ice Age]] begins. Rapid growth of the Antarctic ice cap produces major drop in global sea levels.<ref name=":1" /> Grasslands and prairies thrive as climate dries. ''[[Paraceratherium]]'' largest ever land mammal flourishes. First [[Felidae|felids]] (cats), [[Mustelidae|mustelids]] (e.g. [[weasel]]s, [[otter]]s, [[badger]]s), and [[pinniped]]s (seals, [[sea lion]]s and [[walrus]]es). Whales split into [[Toothed whale|toothed]] and [[filter feeder]]s. [[Multituberculata|Multituberculates]] (rat-like early mammals) go extinct.<ref name=":8" /> | ||
| style="background:{{period color|Chattian}}" |{{Period start|chattian}} {{Period start error|chattian}}<sup>*</sup> | | style="background:{{period color|Chattian}}" |{{Period start|chattian}} {{Period start error|chattian}}<sup>*</sup> | ||
|- | |- | ||
| Line 926: | Line 221: | ||
| rowspan="4" style="background:{{period color|Eocene}}" |[[Eocene]] | | rowspan="4" style="background:{{period color|Eocene}}" |[[Eocene]] | ||
| style="background:{{period color|Priabonian}}" |[[Priabonian]] | | style="background:{{period color|Priabonian}}" |[[Priabonian]] | ||
| rowspan="3" |[[ | | rowspan="3" |[[Subduction]] in the Mediterranean leads to [[Tell Atlas|Tell]]-[[Rif]]-[[Baetic System|Betic]], [[Dinaric Alps|Dinarides]], [[Hellenides]] and [[Taurus Mountains|Taurides]] ([[Alpine orogeny|Alpine]]) [[Orogeny|orogenies]]. [[Eurekan orogeny]], Greenland.<ref name="Torsvik_Cocks 2017" /> [[Zagros Mountains|Zagros orogeny]] as Arabia and Eurasia collide.<ref>{{cite journal |last1=Koshnaw |first1=Renas I. |last2=Schlunegger |first2=Fritz |last3=Stockli |first3=Daniel F. |title=Detrital zircon provenance record of the Zagros mountain building from the Neotethys obduction to the Arabia–Eurasia collision, NW Zagros fold–thrust belt, Kurdistan region of Iraq |journal=Solid Earth |date=3 November 2021 |volume=12 |issue=11 |pages=2479–2501 |doi=10.5194/se-12-2479-2021 |doi-access=free }}</ref> [[Laramide orogeny]] ends.<ref name=":1" /> [[Gulf of Aden]] forms between Africa and Asia.<ref>{{cite journal |last1=Boone |first1=Samuel C. |last2=Balestrieri |first2=Maria-Laura |last3=Kohn |first3=Barry |title=Tectono-Thermal Evolution of the Red Sea Rift |journal=Frontiers in Earth Science |date=12 July 2021 |volume=9 |article-number=713448 |doi=10.3389/feart.2021.713448 |doi-access=free }}</ref> Cooling climate with [[Middle Eocene Climatic Optimum|brief warm period]]. End Eocene Australia and South America move away from Antarctica opening [[Drake Passage|Drake]] and [[Tasmanian Passage|Tasmanian]] passages. [[Antarctic Circumpolar Current|Antarctic Circumpolar current]] forms. Rapid drop in global temperatures. Ice sheets on Antarctica.<ref name=":1" /> [[Canidae|Canids]] ([[Wolf|wolves]] and [[fox]]es), [[Catarrhini|Catarrhine primates]] ([[old world monkey]]s and [[ape]]s), and [[Bird of prey|raptors]] evolve. ''[[Basilosaurus]]'' is first fully aquatic whale.<ref name=":8" /> | ||
| style="background:{{period color|Priabonian}}" |{{Period start|priabonian}} {{Period start error|priabonian}}<sup>*</sup> | | style="background:{{period color|Priabonian}}" |{{Period start|priabonian}} {{Period start error|priabonian}}<sup>*</sup> | ||
|- | |- | ||
| Line 936: | Line 231: | ||
|- | |- | ||
| style="background:{{period color|Ypresian}}" |[[Ypresian]] | | style="background:{{period color|Ypresian}}" |[[Ypresian]] | ||
| | |[[Greenland]] separates from Eurasia and [[Eurasian Basin]] opens in Arctic. [[Indian plate|Greater India]] collides with southern Eurasia, beginning [[Geology of the Himalayas|Himalayan orogeny]]. [[North Atlantic Igneous Province|North Atlantic LIP]] eruptions continue.<ref name="Torsvik_Cocks 2017" /> Major reorganisation of [[Plate tectonics|plate]] motions across Pacific region initiates [[Izu–Bonin–Mariana arc|Izu-Bonin-Mariana]] and [[Tonga–Kermadec subduction zone|Tonga-Kermadec]] [[Subduction|subduction zones]].<ref>{{cite journal |last1=Seton |first1=M. |last2=Müller |first2=R.D. |last3=Zahirovic |first3=S. |last4=Gaina |first4=C. |last5=Torsvik |first5=T. |last6=Shephard |first6=G. |last7=Talsma |first7=A. |last8=Gurnis |first8=M. |last9=Turner |first9=M. |last10=Maus |first10=S. |last11=Chandler |first11=M. |title=Global continental and ocean basin reconstructions since 200Ma |journal=Earth-Science Reviews |date=July 2012 |volume=113 |issue=3–4 |pages=212–270 |doi=10.1016/j.earscirev.2012.03.002 }}</ref> [[Greenhouse and icehouse Earth|Greenhouse]] temperatures continue from [[Paleocene-Eocene Thermal Maximum]] (PETM) as climate affected by North Atlantic LIP eruptions, but global cooling begins from about 50 Ma with changing [[paleogeography]] and [[oceanography]] conditions.<ref name="Scotese et al 2021" /> [[Flowering plant|Angiosperms]] (flowering plants) evolve larger fruits. First [[songbird]]s, [[parrot]]s and [[woodpecker]]s. [[Primate]]s divide into [[Strepsirrhini|strepsirrhines]] ([[lemur]]s and [[loris]]es) and [[Haplorhini|haplorhines]] ([[tarsier]]s and [[Simian|anthropoids]]). [[Artiodactyl]]s (even-toed [[ungulate]]s) appear and split into [[Cetruminantia]] ([[ruminant]]s, [[whale]]s and dolphins), [[Suina]] (pigs), and [[Tylopoda]] (camels and relatives). First [[Carnivora]] (meat-eating mammals). [[Mouse|Mice]], [[rat]]s, [[bat]]s and [[tapir]]s appear. ''[[Eohippus]]'' earliest member of horse family. [[Marsupial]]s reach Australia.<ref name=":8" /> | ||
| style="background:{{period color|Ypresian}}" |{{Period start|ypresian}} {{Period start error|ypresian}}<sup>*</sup> | | style="background:{{period color|Ypresian}}" |{{Period start|ypresian}} {{Period start error|ypresian}}<sup>*</sup> | ||
|- | |- | ||
| rowspan="3" style="background:{{period color|Paleocene}}" |[[Paleocene]] | | rowspan="3" style="background:{{period color|Paleocene}}" |[[Paleocene]] | ||
| style="background:{{period color|Thanetian}}" |[[Thanetian]] | | style="background:{{period color|Thanetian}}" |[[Thanetian]] | ||
| rowspan="3" | | | rowspan="3" |Alpine orogeny develops as [[Tethys Ocean|Neotethys]] closes and Africa begins collision with Eurasia.<ref name="Torsvik_Cocks 2017" /> Pyrenean and Laramide orogenies continue.<ref name="Torsvik_Cocks 2017" /><ref name=":1" /> India drifts rapidly northwards. North Atlantic LIP eruptions start as Proto-[[Iceland hotspot|Icelandic mantle plume]] rises.<ref name="Torsvik_Cocks 2017" /> Subduction zones form along margins of [[Caribbean plate]].<ref>{{cite journal |last1=Montes |first1=Camilo |last2=Rodriguez-Corcho |first2=Andres Felipe |last3=Bayona |first3=German |last4=Hoyos |first4=Natalia |last5=Zapata |first5=Sebastian |last6=Cardona |first6=Agustin |title=Continental margin response to multiple arc-continent collisions: The northern Andes-Caribbean margin |journal=Earth-Science Reviews |date=November 2019 |volume=198 |article-number=102903 |doi=10.1016/j.earscirev.2019.102903 }}</ref> [[Beringia|Bering Straits land bridge]] present during low sea level periods.<ref name="Torsvik_Cocks 2017" /> [[Chicxulub crater|Chicxulub impact]] causes "[[impact winter]]", then climate warms with final eruption of the [[Deccan Traps]] before cool, dry conditions re-established. Rapid rise in global temperatures at onset of PETM due to North Atlantic LIP eruptions.<ref name="Torsvik_Cocks 2017" /><ref name="Scotese et al 2021" /> [[Cretaceous–Paleogene extinction event|End-Cretaceous mass extinction]] about 75% of plant and animal species go extinct, including [[Ammonoidea|ammonoids]], [[Rudists|rudist molluscs]], [[Dinosaur|non-avian dinosaurs]], [[plesiosaur]]s, [[mosasaur]]s and [[pterosaur]]s. Mammals evolve quickly filling vacant [[ecological niche]]s, modern groups of birds diversify and angiosperms become dominant form of plant life. First [[earthworm]]s and [[Tortoise|land turtles]]. [[Phorusrhacidae]] (terror birds) and creodonts (early predatory mammals) evolve. [[Perissodactyla|Perissodactyls]] (odd-toed ungulates) appear and diversify. First primates, [[proboscidea]]ns (elephants), [[Xenarthra|Xenartha]] (sloths, anteaters and armadillos) and rodents.<ref name=":8" /> | ||
| style="background:{{period color|Thanetian}}" |{{Period start|thanetian}} {{Period start error|thanetian}}<sup>*</sup> | | style="background:{{period color|Thanetian}}" |{{Period start|thanetian}} {{Period start error|thanetian}}<sup>*</sup> | ||
|- | |- | ||
| Line 954: | Line 249: | ||
| rowspan="6" style="background:{{period color|Late Cretaceous}}" |[[Late Cretaceous|Upper/Late]] | | rowspan="6" style="background:{{period color|Late Cretaceous}}" |[[Late Cretaceous|Upper/Late]] | ||
| style="background:{{period color|Maastrichtian}}" |[[Maastrichtian]] | | style="background:{{period color|Maastrichtian}}" |[[Maastrichtian]] | ||
| rowspan="12" |[[ | | rowspan="12" |[[Pangaea]] continues to fragment. Africa and South America separate as [[seafloor spreading]] established in South Atlantic. India and Australia move away from Antarctica, and India separates from Madagascar. Central Atlantic propagates north. |Pyrenean orogeny begins as [[Iberian Peninsula|Iberia]] rotates relative to Eurasia. Africa moves northwards.<ref name="Torsvik_Cocks 2017" /> [[Sevier orogeny|Sevier]] and Laramide orogenies, western North America.<ref name="Torsvik_Cocks 2017" /><ref name=":1" /> LIP eruptions include: [[Ontong Java Plateau|Ontong Java-Nui]]; [[Kerguelen Plateau|Kerguelen]]; [[High Arctic Large Igneous Province|High Arctic]] and [[Deccan Traps]].<ref name="Torsvik_Cocks 2017" /><ref name="Scotese et al 2021" /> Highest sea levels in the Phanerozoic, shallow seas extend across large areas of the continents.<ref name="Torsvik_Cocks 2017" /> Greenhouse climate global average temperature peaks c. 28 °C in the Cenomanian-Turonian. Tropical plants and dinosaurs on Antarctica and above Arctic Circle. [[Anoxic event|Oceanic anoxic event]]s (OAEs) result in widespread [[Deposition (geology)|deposition]] of [[Organic-rich sedimentary rocks|organic-rich]] black [[shales]].<ref name="Scotese et al 2021" /> [[Calcareous]] [[foraminifera]] and [[coccolithophore]]s flourish forming massive [[chalk]] deposits. [[Teleost]] (bony fish) radiate.<ref name=":1" /> Predators grow large: plesiosaurs and mosasaurs in the sea;<ref name=":1" /> [[Carnosauria|carcharodontosaurs]] and [[Tyrannosauroidea|tyrannosaurs]] on land.<ref name=":8" /> Modern [[lobster]]s, [[crab]]s, [[shrimp]]s and [[crocodile]]s appear. First [[bee]]s, [[termite]]s, [[ant]]s, [[flea]]s, [[Mantidae|mantids]] and [[snake]]s. Angiosperms (flowering plants) proliferate and develop [[Symbiosis|symbiotic relationships]] with insects. First [[grass]]es. Woody angiosperms evolve including [[rose]], [[magnolia]] and [[Acer pseudoplatanus|sycamore]] families. First marsupials and [[monotreme]]s.<ref name=":1" /><ref name=":8" /> End of the Cretaceous is marked by the Chicxulub impact event and the Cretaceous-Paleogene mass extinction.<ref name="Scotese et al 2021" /> | ||
| style="background:{{period color|Maastrichtian}}" |{{Period start|maastrichtian}} {{Period start error|maastrichtian}}<sup>*</sup> | | style="background:{{period color|Maastrichtian}}" |{{Period start|maastrichtian}} {{Period start error|maastrichtian}}<sup>*</sup> | ||
|- | |- | ||
| Line 994: | Line 289: | ||
| rowspan="3" style="background:{{period color|Late Jurassic}}" |[[Late Jurassic|Upper/Late]] | | rowspan="3" style="background:{{period color|Late Jurassic}}" |[[Late Jurassic|Upper/Late]] | ||
| style="background:{{period color|Tithonian}}" |[[Tithonian]] | | style="background:{{period color|Tithonian}}" |[[Tithonian]] | ||
| rowspan="11" | | | rowspan="11" |Seafloor spreading in the [[Atlantic Ocean|Central Atlantic]] between North America and Africa-South America begins break up of Pangaea. Rifting continues in northern Atlantic and Caribbean. Gondwana splits into East and West Gondwana as Somali and Mozambique basins open. [[Pacific plate]] forms in central Panthalassa. [[Cimmerian Orogeny|Cimmerian]] and Indosinian orogenies continue. Start of [[Andean Volcanic Belt|Andean tectonic cycle]], South America.<ref name="Torsvik_Cocks 2017">{{Cite book |last1=Torsvik |first1=Trond H. |title=Earth history and palaeogeography |last2=Cocks |first2=Leonard Robert Morrison |date=2017 |publisher=Cambridge university press |isbn=978-1-107-10532-4 |location=Cambridge}}</ref> [[Nevadan orogeny]], North America.<ref name=":1" /> [[Mongol-Okhotsk Ocean]] closes forming [[Verkhoyansk Range|Verkhoyansk]]-[[Kolyma Mountains|Kolyma]] mountain belt, Siberia. Neotethys narrows. Greenhouse climate with warmer and cooler periods. Arid conditions across equatorial and subtropical regions; coal and [[bauxite]] deposits in wetter temperate belts. Emplacement of [[Karoo-Ferrar]] LIP leads to global warming and the widespread [[Toarcian Oceanic Anoxic Event|Toarcian oceanic anoxic event]].<ref name="Scotese et al 2021">{{cite journal |last1=Scotese |first1=Christopher R. |last2=Song |first2=Haijun |last3=Mills |first3=Benjamin J.W. |last4=van der Meer |first4=Douwe G. |title=Phanerozoic paleotemperatures: The earth's changing climate during the last 540 million years |journal=Earth-Science Reviews |date=April 2021 |volume=215 |article-number=103503 |doi=10.1016/j.earscirev.2021.103503 |bibcode=2021ESRv..21503503S }}</ref> Rise in global sea levels. Change from [[Aragonite sea|aragonite]] to [[calcite sea]]s.<ref name=":1" /> First large reefs. [[Phytoplankton]] and [[dinoflagellate]]s diversify. First [[coccolithophore]]s. [[Ammonoidea|Ammonoids]] and [[Belemnoidea|bellomnoids]] proliferate.<ref name=":1" /> Major radiation of sharks. ''[[Vieraella]]'' earliest true frog. First modern turtles.<ref name=":8" /> [[Cycadeoidea|Cycads]] dominant forest flora.<ref name=":1" /> Also [[fern]]s, [[conifer]]s and [[ginkgo]]s.<ref name="Scotese et al 2021" /> Dinosaurs rise to dominance, mammals remain small.<ref name=":1" /> First [[Ornithischia]] (e.g. [[Stegosauria|stegasaurs]] and [[Ceratopsidae|ceratopsians]]). [[Sauropoda|Sauropods]] evolve into giants, including [[Brachiosauridae|brachiosaurs]], [[Titanosauria|titanosaurs]], and [[Diplodocidae|diplodocids]]. First [[Ceratosauria|ceratosaurs]], [[Megalosauroidea|megalosaurs]], [[Allosauridae|allosaurs]], and [[Coelurosauria|coelurosaurs]] [[Theropoda|therapods]]. Coelurosaurs, many with feathers, include early [[Tyrannosauroidea|tyrannosaurs]] and [[maniraptora]]ns (ancestors of birds). First [[Pterodactyloidea|pterodactyloids]].<ref name=":8" /> | ||
| style="background:{{period color|Tithonian}}" |{{Period start|tithonian}} {{Period start error|tithonian}} | | style="background:{{period color|Tithonian}}" |{{Period start|tithonian}} {{Period start error|tithonian}} | ||
|- | |- | ||
| Line 1,032: | Line 327: | ||
| rowspan="3" style="background:{{period color|Late Triassic}}" |[[Late Triassic|Upper/Late]] | | rowspan="3" style="background:{{period color|Late Triassic}}" |[[Late Triassic|Upper/Late]] | ||
| style="background:{{period color|Rhaetian}}" |[[Rhaetian]] | | style="background:{{period color|Rhaetian}}" |[[Rhaetian]] | ||
| rowspan="7" |[[ | | rowspan="7" |Pangaea forms an arc extending from almost pole to pole. [[Siberian Traps]] eruptions wane, but hot house climate continues.<ref name="Torsvik_Cocks 2017" /> [[Cimmeria (continent)|Cimmerian terranes]] collide with Eurasia: Indosinian orogeny in east; [[Cimmerian Orogeny|Cimmerian orogeny]] in west.<ref name="Torsvik_Cocks 2017" /><ref>{{cite journal |last1=Song |first1=Dongfang |last2=Xiao |first2=Wenjiao |last3=Ao |first3=Songjian |last4=Mao |first4=Qigui |last5=Wan |first5=Bo |last6=Zeng |first6=Hao |title=Contemporaneous closure of the Paleo-Asian Ocean in the Middle-Late Triassic: A synthesis of new evidence and tectonic implications for the final assembly of Pangea |journal=Earth-Science Reviews |date=June 2024 |volume=253 |article-number=104771 |doi=10.1016/j.earscirev.2024.104771 |bibcode=2024ESRv..25304771S }}</ref> [[Sonoma orogeny|Sonoma]] (western Laurussia), and [[Hunter–Bowen orogeny|Hunter-Bowen]] (Australia) orogenies continue.<ref name="Torsvik_Cocks 2017" /><ref name="Rosenbaum 2018" /> Late Triassic, emplacement of the [[Central Atlantic magmatic province]] (CAMP) followed by [[seafloor spreading]] marks start of Pangaea break up.<ref>{{cite journal |last1=Peace |first1=Alexander L. |last2=Phethean |first2=J.J.J. |last3=Franke |first3=D. |last4=Foulger |first4=G.R. |last5=Schiffer |first5=C. |last6=Welford |first6=J.K. |last7=McHone |first7=G. |last8=Rocchi |first8=S. |last9=Schnabel |first9=M. |last10=Doré |first10=A.G. |title=A review of Pangaea dispersal and Large Igneous Provinces – In search of a causative mechanism |journal=Earth-Science Reviews |date=July 2020 |volume=206 |article-number=102902 |doi=10.1016/j.earscirev.2019.102902 |bibcode=2020ESRv..20602902P }}</ref> [[Archosaur]]s divide into [[pseudosuchia]] (crocodiles), and [[Avemetatarsalia|ornithodirans]] (dinosaurs and [[pterosaur]]s). [[Mammaliaformes]] evolve from [[Cynodontia|cynodonts]].<ref name=":8" /> Evidence of [[endotherm]]y (warm-bloodedness) in dinosaurs and mammals.<ref name=":12">{{cite journal |last1=Benton |first1=Michael J. |last2=Wu |first2=Feixiang |title=Triassic Revolution |journal=Frontiers in Earth Science |date=17 June 2022 |volume=10 |article-number=899541 |doi=10.3389/feart.2022.899541 |bibcode=2022FrEaS..10.9541B |doi-access=free }}</ref> First [[teleost]]s (modern ray-finned fish). [[Ichthyosauria|Ichthyosaurs]], and [[sauropterygia]]ns plesiosaurs, [[nothosaur]]s, [[Placodontia|placodonts]]) appear.<ref name=":12" /> First [[scleractinia]]n (hard coral) reefs. First [[wasp]]s and [[Phasmatodea|stick insects]].<ref name=":8" /> Late Triassic eruptions of [[Wrangellia terrane|Wrangellia]] LIP raises temperatures, intensifies Pangaea [[monsoon]]s and increases rainfall ([[Carnian pluvial episode]]).<ref name="Scotese et al 2021" /> [[Bennettitales]], modern [[fern]]s and [[conifer]]s appear. First [[Lepidoptera]] (moths and butterflies). Modern groups of [[phytoplankton]] appear.<ref name=":12" /> Manicouagan [[bolide]] impact reduces global temperatures, before CAMP eruptions increases them and triggers [[Triassic–Jurassic extinction|Triassic-Jurassic mass extinction]].<ref>{{cite book |last1=Ogg |first1=J.G. |last2=Chen |first2=Z.-Q. |last3=Orchard |first3=M.J. |last4=Jiang |first4=H.S. |title=Geologic Time Scale 2020 |chapter=The Triassic Period |date=2020 |pages=903–953 |doi=10.1016/B978-0-12-824360-2.00025-5 |isbn=978-0-12-824360-2 }}</ref><ref name="Scotese et al 2021" /> Major loss of reef ecosystems, reduction in marine genera, [[conodont]]s die out. Major changes in terrestrial flora. Loss of vertebrate genera, including non-mammalian [[Therapsida|therapsids]]. [[Crocodylomorpha|Crocodylomorphs]] only pseudosuchians to survive.<ref name=":8" /><ref name="Scotese et al 2021" /> | ||
| style="background:{{period color|Rhaetian}}" |~{{Period start|rhaetian}} {{Period start error|rhaetian}} | | style="background:{{period color|Rhaetian}}" |~{{Period start|rhaetian}} {{Period start error|rhaetian}} | ||
|- | |- | ||
| Line 1,059: | Line 354: | ||
| rowspan="2" style="background:{{period color|Lopingian}}" |[[Lopingian]] | | rowspan="2" style="background:{{period color|Lopingian}}" |[[Lopingian]] | ||
| style="background:{{period color|Changhsingian}}" |[[Changhsingian]] | | style="background:{{period color|Changhsingian}}" |[[Changhsingian]] | ||
| rowspan="9" | | | rowspan="9" |Pangaea at its maximum extent. [[Uralian orogeny|Ural]] and [[Alleghanian orogeny|Alleghanian]] orogenies continue.<ref name="Torsvik_Cocks 2017" /> Hunter-Bowen orogeny, eastern Australia;<ref name="Rosenbaum 2018">{{cite journal |last1=Rosenbaum |first1=Gideon |title=The Tasmanides: Phanerozoic Tectonic Evolution of Eastern Australia |journal=Annual Review of Earth and Planetary Sciences |date=30 May 2018 |volume=46 |issue=1 |pages=291–325 |doi=10.1146/annurev-earth-082517-010146 |bibcode=2018AREPS..46..291R }}</ref> [[Sonoma orogeny]], western Laurussia. [[Kazakhstania]] and Tarim collide with Siberia. [[Orogenic collapse]] of [[Variscan orogeny]] and early extension along the lines of the future Atlantic, Indian and Southern Oceans. Opening of Neo-Tethys Ocean as Cimmerian terranes rift from northeast Gondwana.<ref name="Torsvik_Cocks 2017" /> [[Late Paleozoic icehouse|Late Paleozoic Ice Age]] wanes and humid, icehouse climate give way to arid, greenhouse conditions.<ref name=":10">{{cite book |last1=Henderson |first1=C.M. |last2=Davydov And |first2=V.I. |last3=Wardlaw |first3=B.R. |last4=Gradstein |first4=F.M. |last5=Hammer |first5=O. |title=The Geologic Time Scale |chapter=The Permian Period |date=2012 |pages=653–679 |doi=10.1016/B978-0-444-59425-9.00024-X |isbn=978-0-444-59425-9 }}</ref> Global average temperatures rise from c. 12° to over 30° at Permo-Triassic boundary.<ref name="Scotese et al 2021" /> Desert dune sands and [[evaporite]]s dominate interior of Pangea.<ref name="Torsvik_Cocks 2017" /><ref name=":10" /> Coal swamps at high latitudes and humid coastal regions.<ref name="Torsvik_Cocks 2017" /><ref name="Scotese et al 2021" /> [[Moss]]es, [[Beetle|Coleoptera]] (beetles) and [[Fly|Diptera]] (two-winged flies) appear. [[Diapsid]]s split into archosaurs (crocodiles and dinosaurs) and [[Lepidosauria|lepidosaurs]] (lizards and snakes). First marine reptiles. Therapsids and cynodonts evolve from [[Synapsida|synapsids]].<ref name=":8" /> [[Capitanian mass extinction event|Guadalupian-Lopingian boundary mass extinction]] linked to eruption of [[Emeishan Traps|Emeishan]] LIP, South China.<ref name=":1" /> At the Permo-Triassic boundary, eruption of the [[Siberian Traps]] LIP releases vast amounts of CO<sub>2</sub> leading to extreme global warming, and the [[Permian–Triassic extinction event|end-Permian mass extinction]]. [[Anoxic waters]] from the deep ocean move up to the shallows,<ref name="Scotese et al 2021" /> eliminating [[trilobite]]s, [[Rugosa|rugose]] and [[Tabulata|tabulate]] corals, and [[placoderm]]s. [[Brachiopod]]s, ammonoids, sharks, [[Osteichthyes|bony fish]], and [[crinoid]]s see major reductions.<ref name=":10" /> On land, forests disappear. [[Palaeodictyopteroidea|Palaeodictyopterida]] and many insect groups go extinct, as do all non-therapsid synapsids and most therapsid genera.<ref name=":10" /><ref name=":1" /><ref name=":8" /> | ||
| style="background:{{period color|Changhsingian}}" |{{Period start|changhsingian}} {{Period start error|changhsingian}}<sup>*</sup> | | style="background:{{period color|Changhsingian}}" |{{Period start|changhsingian}} {{Period start error|changhsingian}}<sup>*</sup> | ||
|- | |- | ||
| Line 1,091: | Line 386: | ||
| rowspan="4" style="background:{{period color|Pennsylvanian}}" |[[Pennsylvanian (geology)|Pennsylvanian]]<br/>{{efn|group=note|name=MissiPenns|This is divided into Lower/Early, Middle, and Upper/Late series/epochs}} | | rowspan="4" style="background:{{period color|Pennsylvanian}}" |[[Pennsylvanian (geology)|Pennsylvanian]]<br/>{{efn|group=note|name=MissiPenns|This is divided into Lower/Early, Middle, and Upper/Late series/epochs}} | ||
| style="background:{{period color|Gzhelian}}" |[[Gzhelian]] | | style="background:{{period color|Gzhelian}}" |[[Gzhelian]] | ||
| rowspan="4" |[[ | | rowspan="4" |Continuation of the Variscan orogeny ([[Ouachita orogeny|Ouachita]] and Alleghanian orogenies) with growth of the [[Central Pangean Mountains]].<ref name="Torsvik_Cocks 2017" /> Ural orogeny continues with continental collision between Kazakhstania and [[Laurasia|Laurussia]].<ref>{{cite journal |last1=Puchkov |first1=Victor N. |title=The evolution of the Uralian orogen |journal=Geological Society, London, Special Publications |date=January 2009 |volume=327 |issue=1 |pages=161–195 |doi=10.1144/SP327.9 |bibcode=2009GSLSP.327..161P }}</ref> Humid, [[Coal forest|coal swamps]] form in [[foreland basin]]s of the Central Pangean Mountains and around [[North China Craton|North]] and [[South China Craton|South China]] cratons.<ref>{{cite journal |last1=Nelsen |first1=Matthew P. |last2=DiMichele |first2=William A. |last3=Peters |first3=Shanan E. |last4=Boyce |first4=C. Kevin |title=Delayed fungal evolution did not cause the Paleozoic peak in coal production |journal=Proceedings of the National Academy of Sciences |date=March 2016 |volume=113 |issue=9 |pages=2442–2447 |doi=10.1073/pnas.1517943113 |doi-access=free |pmc=4780611 |pmid=26787881 |bibcode=2016PNAS..113.2442N }}</ref> As the Late Paleozoic icehouse (LPIA) continues, waxing and waning of ice sheets causes rapid changes in global sea level, flooding these regions and depositing [[Cyclothems|cyclothem]] sequences.<ref>{{cite journal |last1=Fielding |first1=Christopher R. |title=Late Palaeozoic cyclothems – A review of their stratigraphy and sedimentology |journal=Earth-Science Reviews |date=June 2021 |volume=217 |article-number=103612 |doi=10.1016/j.earscirev.2021.103612 |bibcode=2021ESRv..21703612F }}</ref> Atmospheric oxygen levels rise to over 25% before decreasing again.<ref name=":7">{{cite journal |last1=Cannell |first1=Alan |last2=Blamey |first2=Nigel |last3=Brand |first3=Uwe |last4=Escapa |first4=Ignacio |last5=Large |first5=Ross |title=A revised sedimentary pyrite proxy for atmospheric oxygen in the Paleozoic: Evaluation for the Silurian-Devonian-Carboniferous period and the relationship of the results to the observed biosphere record |journal=Earth-Science Reviews |date=August 2022 |volume=231 |article-number=104062 |doi=10.1016/j.earscirev.2022.104062 |bibcode=2022ESRv..23104062C }}</ref> Appearance of [[aragonite]] reef builders, including [[algae]] and [[sponges]].<ref name=":1" /> Freshwater [[Eurypterid]]s (sea scorpions). On land, [[Neoptera]] appear, and [[Miomoptera]] show earliest evidence for complete [[metamorphosis]]. First true terrestrial [[amphibian]]s. [[Amniote]]s appear and split into two groups: [[Sauropsida|sauropsids]] (reptiles) and synapsids (mammals).<ref name=":8">{{Cite book |last=Parker |first=Steve |title=Evolution: the Whole Story |date=2015 |publisher=Thames & Hudson Ltd |isbn=978-0-500-29173-3 |location=London}}</ref> ''[[Lepidodendron]]'' and ''[[Sigillaria]]'' [[Lycopodiopsida|lycopod]] trees dominate coal swamps, with smaller [[Equisetidae|sphenopsids]] (horsetails) and [[Pteridospermatophyta|seed fern]]s between. [[Gymnosperm]]s, including [[conifer]]s and [[cycad]]s grow on drier ground.<ref name=":1" /> LPIA peaks at Carboniferous-Permian boundary. A drop in CO<sub>2</sub> levels and increase in arid conditions<ref name=":9">{{cite journal |last1=Montañez |first1=Isabel Patricia |title=Current synthesis of the penultimate icehouse and its imprint on the Upper Devonian through Permian stratigraphic record |journal=Geological Society, London, Special Publications |date=January 2022 |volume=512 |issue=1 |pages=213–245 |doi=10.1144/SP512-2021-124 |bibcode=2022GSLSP.512..213M }}</ref> leads to change in woodland vegetation ([[Carboniferous rainforest collapse]]).<ref>{{cite journal |last1=Lucas |first1=Spencer G. |last2=DiMichele |first2=William A. |last3=Opluštil |first3=Stanislav |last4=Wang |first4=Xiangdong |title=An introduction to ice ages, climate dynamics and biotic events: the Late Pennsylvanian world |journal=Geological Society, London, Special Publications |date=14 June 2023 |volume=535 |issue=1 |pages=1–15 |doi=10.1144/SP535-2022-334 }}</ref> | ||
| style="background:{{period color|Gzhelian}}" |{{Period start|gzhelian}} {{Period start error|gzhelain}} | | style="background:{{period color|Gzhelian}}" |{{Period start|gzhelian}} {{Period start error|gzhelain}} | ||
|- | |- | ||
| Line 1,097: | Line 392: | ||
| style="background:{{period color|Kasimovian}}" |{{Period start|kasimovian}} {{Period start error|kasimovian}} | | style="background:{{period color|Kasimovian}}" |{{Period start|kasimovian}} {{Period start error|kasimovian}} | ||
|- | |- | ||
| style="background:{{period color|Moscovian}}" |[[Moscovian | | style="background:{{period color|Moscovian}}" |[[Moscovian age|Moscovian]] | ||
| style="background:{{period color|Moscovian}}" |{{Period start|moscovian}} {{Period start error|moscovian}} | | style="background:{{period color|Moscovian}}" |{{Period start|moscovian}} {{Period start error|moscovian}} | ||
|- | |- | ||
| Line 1,105: | Line 400: | ||
| rowspan="3" style="background:{{period color|Mississippian}}" |[[Mississippian (geology)|Mississippian]]<br/>{{efn|group=note|name=MissiPenns}} | | rowspan="3" style="background:{{period color|Mississippian}}" |[[Mississippian (geology)|Mississippian]]<br/>{{efn|group=note|name=MissiPenns}} | ||
| style="background:{{period color|Serpukhovian}}" |[[Serpukhovian]] | | style="background:{{period color|Serpukhovian}}" |[[Serpukhovian]] | ||
| rowspan="3" | | | rowspan="3" |Continents form a near circle around the opening Paleo-Tethys Ocean. Gondwana forms the southern to southwestern margin; Laurussia the west; Siberia, Amuria and Kazakhstania the north; North and South China the northeast; and, Annamia the eastern margin.<ref name="Torsvik_Cocks 2017" /> The [[terrane]]s collide with southeastern Laurussia during the Variscan orogeny. [[Antler orogeny]] continues, and opening of the [[Slide Mountain Ocean]] along western margin of Laurussia.<ref>{{cite journal |last1=Domeier |first1=Mathew |last2=Torsvik |first2=Trond H. |title=Plate tectonics in the late Paleozoic |journal=Geoscience Frontiers |date=May 2014 |volume=5 |issue=3 |pages=303–350 |doi=10.1016/j.gsf.2014.01.002 |bibcode=2014GeoFr...5..303D }}</ref> Closure of [[Ural Ocean]] between Kazakhstania and Laurussia during the Ural orogeny. Development of [[Altai Mountains|Altai]] accretionary complexes along north and eastern margin of the Paleo-Tethys.<ref>{{cite journal |last1=Xu |first1=Yan |last2=Han |first2=Bao-Fu |last3=Liao |first3=Wen |last4=Li |first4=Ang |title=The Serpukhovian–Bashkirian Amalgamation of Laurussia and the Siberian Continent and Implications for Assembly of Pangea |journal=Tectonics |date=March 2022 |volume=41 |issue=3 |article-number=e2022TC007218 |doi=10.1029/2022TC007218 |bibcode=2022Tecto..4107218X }}</ref> Main phase of LPIA begins. Drop in global sea levels, extensive glaciation across Gondwana.<ref name=":9" /> Increasing atmospheric oxygen levels.<ref name=":7" /> Change from [[Calcite sea|calcite]] to aragonite seas.<ref name=":1" /> [[Evolutionary radiation]]s after the Late Devonian extinctions include brachiopods, bivalves, echinoderms, ammonoids, gastropods, sharks and ray-finned bony fish. [[Placoderm]]s and [[graptolite]]s die out. Proetida only group of trilobites.<ref name=":1" /><ref name=":8" /> First freshwater mollusks and sharks.<ref name=":1" /> ''[[Arthropleura]]'' (millipede) largest ever terrestrial arthropod. First flying insects ''Paleodictyopora.'' Fish-like (''[[Pederpes]]'') and semi-aquatic [[tetrapods]] (''[[Eucritta]]'') appear on land.<ref name=":8" /> Seedless vascular plants and seed ferns diversify.<ref name=":1" /> | ||
| style="background:{{period color|Serpukhovian}}" |{{Period start|serpukhovian}} {{Period start error|serpukhovian}} | | style="background:{{period color|Serpukhovian}}" |{{Period start|serpukhovian}} {{Period start error|serpukhovian}} | ||
|- | |- | ||
| Line 1,117: | Line 412: | ||
| rowspan="2" style="background:{{period color|Late Devonian}}" |[[Late Devonian|Upper/Late]] | | rowspan="2" style="background:{{period color|Late Devonian}}" |[[Late Devonian|Upper/Late]] | ||
| style="background:{{period color|Famennian}}" |[[Famennian]] | | style="background:{{period color|Famennian}}" |[[Famennian]] | ||
| rowspan="7" | | | rowspan="7" |Paleo-Tethys continues to open as the Armorican Terrane Assemblage (ATA) drifts north and Annamia-South China moves away from Gondwana.<ref name="Torsvik_Cocks 2017" /><ref>{{cite journal |last1=Golonka |first1=Jan |title=Late Devonian paleogeography in the framework of global plate tectonics |journal=Global and Planetary Change |date=March 2020 |volume=186 |article-number=103129 |doi=10.1016/j.gloplacha.2020.103129 |bibcode=2020GPC...18603129G }}</ref> [[Rheic Ocean]] closes as ATA collides with Laurussia beginning the Variscan orogeny. Other orogenies: Antler, [[Innuitian orogeny|Ellesmerian]], and [[Acadian orogeny|Acadian]] (Laurussia); Achalian (Argentina); [[Lachlan Fold Belt|Tabberabberan/Lachlan]] (Australia); [[Ross orogeny|Ross]] (Antarctica); Kazakh ([[Kazakhstania]]).<ref name="Torsvik_Cocks 2017" /> Period of high sea-levels, greenhouse conditions but decreasing atmospheric CO<sub>2</sub> levels and slowly cooling climate with glaciations towards end.<ref name=":6">{{cite journal |last1=Qie |first1=Wenkun |last2=Algeo |first2=Thomas J. |last3=Luo |first3=Genming |last4=Herrmann |first4=Achim |title=Global events of the Late Paleozoic (Early Devonian to Middle Permian): A review |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |date=October 2019 |volume=531 |article-number=109259 |doi=10.1016/j.palaeo.2019.109259 |bibcode=2019PPP...53109259Q |url=https://repository.lsu.edu/geo_pubs/1113 }}</ref> [[Vascular plant]]s increase in size, develop large root systems and spread to upland areas. First forests, seed plants, and modern soil orders appear ([[alfisol]]s and [[ultisol]]s).<ref name=":6" /> Growth of massive reef systems. Major radiation of [[Gnathostomata|jawed fish]] with appearance of [[Actinopterygii|ray-finned]], [[Sarcopterygii|lobe-finned]], and [[Chondrichthyes|cartilaginous]] fish. Appearance of tetrapods (evolved from lobe-finned fish). Early amphibians move on to land. First ammonoids.<ref name=":1" /> Emplacement of the Viley and Pripyat–Dniepr–Donets large igneous provinces coincide with global marine anoxic events and the [[Late Devonian mass extinction|Kellwasser]] (c. 372 Ma) and [[Hangenberg event|Hangenberg]] (c. 359 Ma) mass extinctions.<ref name=":6" /> Kellwasser extinction: c. 20% of families and c. 50% of genera of marine invertebrates lost. Tabulate coral and [[Stromatoporoidea|stromatoporoid]] reef ecosystems wiped out. Loss of placoderms and many groups of [[Agnatha|jawless fish]]. Hangenberg extinction: loss of c. 16% of marine families and c. 21% of marine genera, including ammonoids, [[ostracod]]s and sharks.<ref name=":6" /><ref>{{cite journal |last1=Ernst |first1=Richard E. |last2=Rodygin |first2=Sergei A. |last3=Grinev |first3=Oleg M. |title=Age correlation of Large Igneous Provinces with Devonian biotic crises |journal=Global and Planetary Change |date=January 2020 |volume=185 |article-number=103097 |doi=10.1016/j.gloplacha.2019.103097 |bibcode=2020GPC...18503097E }}</ref> | ||
| style="background:{{period color|Famennian}}" |{{Period start|famennian}} {{Period start error|famennian}}<sup>*</sup> | | style="background:{{period color|Famennian}}" |{{Period start|famennian}} {{Period start error|famennian}}<sup>*</sup> | ||
|- | |- | ||
| Line 1,142: | Line 438: | ||
| rowspan="8" style="background:{{period color|Silurian}}" |[[Silurian]] | | rowspan="8" style="background:{{period color|Silurian}}" |[[Silurian]] | ||
| colspan="2" style="background:{{period color|Pridoli}}" |[[Pridoli epoch|Pridoli]] | | colspan="2" style="background:{{period color|Pridoli}}" |[[Pridoli epoch|Pridoli]] | ||
| rowspan="8" | | | rowspan="8" |Laurentia and Avalonia-Baltica collide as Iapetus Ocean closes, [[Caledonian orogeny|Caledonian]]-[[Scandian orogeny|Scandian]] orogeny, and formation of [[Laurasia|Laurussia]]. Other orogenies: Salinic (Appalachians); Famatinian (South America) tapers off; [[Lachlan Fold Belt|Lachlan]] (Australia).<ref name="Torsvik_Cocks 2017" /><ref name=":5">{{cite journal |last1=Golonka |first1=Jan |last2=Porębski |first2=Szczepan J. |last3=Waśkowska |first3=Anna |title=Silurian paleogeography in the framework of global plate tectonics |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |date=July 2023 |volume=622 |article-number=111597 |doi=10.1016/j.palaeo.2023.111597 |bibcode=2023PPP...62211597G }}</ref> Series of microcontinents and North China separate opening Paleo-Tethys and closing Paleoasian Ocean.<ref name=":5" /> Rheic Ocean widens between Gondwana and Laurussia. Siberia drifts north of equator.<ref name="Torsvik_Cocks 2017" /> Temperatures increase as Hirnantian glaciation ends. Sea levels rise. Deposition of black shales, North Africa and Arabia, major [[hydrocarbon]] [[source rock]]s.<ref name="Torsvik_Cocks 2017" /> Fluctuating climate with glacial advances results in changing ocean conditions causes extinction events, followed by ecological recoveries.<ref>{{cite journal |last1=Cooper |first1=Roger A. |last2=Sadler |first2=Peter M. |last3=Munnecke |first3=Axel |last4=Crampton |first4=James S. |title=Graptoloid evolutionary rates track Ordovician–Silurian global climate change |journal=Geological Magazine |date=March 2014 |volume=151 |issue=2 |pages=349–364 |doi=10.1017/S0016756813000198 |bibcode=2014GeoM..151..349C }}</ref> Widespread evaporite deposition and hothouse climate by late Silurian.<ref name=":1" /><ref name="Scotese et al 2021" /> After end-Ordovician mass extinction, major radiation of graptolites, bivalves, gastropods, nautiloids, brachiopods, and crinoids. Increase in trilobites, but never fully recover. Corals and stromatoporiods diversify to produce large reefs. Proliferation of eurypterid arthropods. Earliest jawed fish ([[Acanthodii|acanthodians]]). Appearance of [[ostracoderm]]s. Appearance of vascular plants. First land animals including [[Myriapoda|myriapods]]. First freshwater fish.<ref name=":1" /> | ||
| style="background:{{period color|Pridoli}}" |{{Period start|pridoli}} {{Period start error|pridoli}}<sup>*</sup> | | style="background:{{period color|Pridoli}}" |{{Period start|pridoli}} {{Period start error|pridoli}}<sup>*</sup> | ||
|- | |- | ||
| Line 1,172: | Line 468: | ||
| rowspan="3" style="background:{{period color|Late Ordovician}}" |[[Late Ordovician|Upper/Late]] | | rowspan="3" style="background:{{period color|Late Ordovician}}" |[[Late Ordovician|Upper/Late]] | ||
| style="background:{{period color|Hirnantian}}" |[[Hirnantian]] | | style="background:{{period color|Hirnantian}}" |[[Hirnantian]] | ||
| rowspan="7" |Most continents lay in equatorial regions. Gondwana stretched to south pole. Panthalassic Ocean covered northern hemisphere. Avalonia rifted from Gondwana closing Iapetus Ocean in front, opening Rheic Ocean behind. South China close to Gondwana; North China between Siberia and Gondwana. Orogenies: [[Famatinian orogeny|Famatinian]] | | rowspan="7" |Most continents lay in equatorial regions. Gondwana stretched to south pole. Panthalassic Ocean covered northern hemisphere. Avalonia rifted from Gondwana closing Iapetus Ocean in front, opening Rheic Ocean behind. South China close to Gondwana; North China between Siberia and Gondwana. Orogenies: [[Famatinian orogeny|Famatinian]] (South America); Benambran (Australia); [[Taconic orogeny|Taconic]] (Laurentia). Baltica and Siberia drift north.<ref name="Torsvik_Cocks 2017" /> Early greenhouse climate, cooling to icehouse conditions during [[Hirnantian glaciation|Hirnantian Ice Age]]. Increase in atmospheric O<sub>2</sub>.<ref name=":3">{{cite journal |last1=Liu |first1=Mu |last2=Bao |first2=Xiujuan |last3=Harper |first3=David A.T. |last4=Algeo |first4=Thomas |last5=Zhao |first5=Mingyu |last6=Saltzman |first6=Matthew |last7=Zhang |first7=Wang |last8=Chen |first8=Daizhao |last9=Yuan |first9=Shuai |last10=Chen |first10=Yihui |last11=Wei |first11=Mengyu |last12=Zhang |first12=Junpeng |last13=Luan |first13=Xiaocong |last14=Zhang |first14=Yuandong |last15=Yang |first15=Xiangrong |last16=Hu |first16=Yongyun |title=Diversification to extinction: oceanic and climatic context of the Ordovician |journal=Earth-Science Reviews |date=October 2025 |volume=269 |article-number=105194 |doi=10.1016/j.earscirev.2025.105194 |bibcode=2025ESRv..26905194L }}</ref> [[Great Ordovician Biodiversification Event]], major increase in new genera e.g. brachiopods, trilobites, corals, echinoderms, bryozoans, gastropods, bivalves, nautiloids, graptolites, and conodonts. Very high sea levels expand shallow continental seas, increase range of ecological niches.<ref name=":4">{{cite book |last1=Cooper |first1=R.A. |last2=Sadler |first2=P.M. |last3=Hammer |first3=O. |last4=Gradstein |first4=F.M. |title=The Geologic Time Scale |chapter=The Ordovician Period |date=2012 |pages=489–523 |doi=10.1016/B978-0-444-59425-9.00020-2 |isbn=978-0-444-59425-9 }}</ref> Modern marine ecosystems established.<ref name=":3" /> Earliest jawless fish. Tabulate corals and stromatoporoids dominant reef builders. Nautiloids main predators.<ref name=":1" /> Appearance of eurypterids and asteroids. Spread of early land plants.<ref name=":3" /> [[Late Ordovician mass extinction]], loss of ~85 % of marine invertebrate species. Two pulses: first with onset of glaciation affects tropical fauna; second at end of ice age, warming climate impacts cool water species.<ref name=":1" /> Drastic reduction in trilobite, brachiopod, graptolite, echinoderm, conodont, coral, and chitinozoan genera.<ref name=":4" /> | ||
| style="background:{{period color|Hirnantian}}" |{{Period start|hirnantian}} {{Period start error|hirnantian}}<sup>*</sup> | | style="background:{{period color|Hirnantian}}" |{{Period start|hirnantian}} {{Period start error|hirnantian}}<sup>*</sup> | ||
|- | |- | ||
| Line 1,198: | Line 494: | ||
| rowspan="3" style="background:{{period color|Furongian}}" |[[Furongian]] | | rowspan="3" style="background:{{period color|Furongian}}" |[[Furongian]] | ||
| style="background:{{period color|Stage 10}}" |[[Cambrian Stage 10|Stage 10]] | | style="background:{{period color|Stage 10}}" |[[Cambrian Stage 10|Stage 10]] | ||
| rowspan="10" |Gondwana stretched from the south pole to equator, separated from Laurentia and Baltica by the Iapetus Ocean. Siberia lay close to the equator, north of Baltica; North and South China close to equatorial Gondwana. Orogenies: [[Cadomian Orogeny|Cadomian]] | | rowspan="10" |Gondwana stretched from the south pole to equator, separated from Laurentia and Baltica by the Iapetus Ocean. Siberia lay close to the equator, north of Baltica; North and South China close to equatorial Gondwana. Orogenies: [[Cadomian Orogeny|Cadomian]] (N.Africa/southern Europe); [[Kuunga orogeny|Kuunga]] (central Gondwana); [[Famatinian orogeny|Famatinian]] orogeny (South America); [[Adelaide Superbasin|Delamerian]] (Australia).<ref name="Torsvik_Cocks 2017" /> Greenhouse climate. High atmospheric CO<sub>2</sub> levels. Atmospheric oxygen levels rose with increase in photosynthesising organisms.<ref name=":0">{{cite journal |last1=Pruss |first1=Sara B. |last2=Gill |first2=Benjamin C. |title=Life on the Edge: The Cambrian Marine Realm and Oxygenation |journal=Annual Review of Earth and Planetary Sciences |date=23 July 2024 |volume=52 |issue=1 |pages=109–132 |doi=10.1146/annurev-earth-031621-070316 |bibcode=2024AREPS..52..109P }}</ref> Early aragonite seas replaced by mixed aragonite-calcite seas with many animals developing CaCO<sub>3</sub> skeletons.<ref>{{cite journal |last1=Xiong |first1=Yi |last2=Wood |first2=Rachel |last3=Pichevin |first3=Laetitia |title=The record of sea water chemistry evolution during the Ediacaran–Cambrian from early marine cements |journal=The Depositional Record |date=May 2023 |volume=9 |issue=3 |pages=508–525 |doi=10.1002/dep2.211 |bibcode=2023DepRe...9..508X }}</ref> Rapid diversification of animals ([[Cambrian explosion|Cambrian Explosion]]), most modern animal phyla appear, e.g. arthropods; molluscs; annelids; echinoderms; bryozoa; priapulids; brachiopods; hemichordates; and, chordates. Radiations of [[Small shelly fauna|small shelly fossils]].<ref>{{cite book |last1=Peng |first1=S. |last2=Babcock |first2=L.E. |last3=Cooper |first3=R.A. |title=The Geologic Time Scale |chapter=The Cambrian Period |date=2012 |pages=437–488 |doi=10.1016/B978-0-444-59425-9.00019-6 |isbn=978-0-444-59425-9 }}</ref> Giant [[Anomalocarididae|anomalocarids]] (arthropods) dominant predators. Increase in bioturbation and grazing led to decline in [[stromatolite]]s.<ref name=":1">{{Cite book |last1=Stanley |first1=Steven |title=Earth System Science |last2=Luczaj |first2=John |publisher=W.H.Freeman and Company |year=2015 |isbn=978-1-319-15402-8 |edition=4th |location=New York}}</ref> Varying oxygen levels in oceans led to series of extinction events followed by radiations, including: earliest Cambrian loss of the Ediacaran [[acritarch]]s; [[End-Botomian mass extinction|end-Botomian extinction]], linked to the Kalkarindji large igneous province eruptions (c. 514 Ma) with loss of [[Archaeocyatha|archaeocyathids]] (early Cambrian reef builders) and hyoliths; and, end-Cambrian reduction in trilobite diversity.<ref name=":0" /><ref>{{cite journal |last1=Myrow |first1=Paul M. |last2=Goodge |first2=John W. |last3=Brock |first3=Glenn A. |last4=Betts |first4=Marissa J. |last5=Park |first5=Tae-Yoon S. |last6=Hughes |first6=Nigel C. |last7=Gaines |first7=Robert R. |title=Tectonic trigger to the first major extinction of the Phanerozoic: The early Cambrian Sinsk event |journal=Science Advances |date=29 March 2024 |volume=10 |issue=13 |article-number=eadl3452 |doi=10.1126/sciadv.adl3452 |pmc=10980278 |pmid=38552008 |bibcode=2024SciA...10L3452M }}</ref><ref name=":1" /> Many fossil [[lagerstätte]]n, including [[Burgess Shale]] and [[Maotianshan Shales|Chengjiang Formation]], formed by rapid burial in anoxic conditions.<ref name=":0" /> | ||
| style="background:{{period color|Stage 10}}" |~{{Period start|cambrian stage 10}} | | style="background:{{period color|Stage 10}}" |~{{Period start|cambrian stage 10}} | ||
|- | |- | ||
| Line 1,234: | Line 530: | ||
| rowspan="3" style="background:{{period color|Neoproterozoic}}" |[[Neoproterozoic]] | | rowspan="3" style="background:{{period color|Neoproterozoic}}" |[[Neoproterozoic]] | ||
| style="background:{{period color|Ediacaran}}" |[[Ediacaran]] | | style="background:{{period color|Ediacaran}}" |[[Ediacaran]] | ||
| colspan="3" | | | colspan="3" |As [[Rodinia]] breaks up Gondwana begins to assemble with the [[Pan-African orogeny|Pan-African]] (Africa and South America), [[East African Orogeny|East African]] (Africa, India and Arabia) and Kuungan (India, eastern Antarctica and western Australia) orogenies.<ref name="Torsvik_Cocks 2017" /><ref name=":13">{{Cite journal |last=Li |first=Zheng-Xiang |last2=Liu |first2=Yebo |last3=Ernst |first3=Richard |date=2023-03-01 |title=A dynamic 2000—540 Ma Earth history: From cratonic amalgamation to the age of supercontinent cycle |journal=Earth-Science Reviews |volume=238 |article-number=104336 |doi=10.1016/j.earscirev.2023.104336 }}</ref> Rapid rise in [[eukaryote]] diversity and numbers, including early animals. First [[Biomineralization|biomineralising]] animals.<ref name=":14" /> First [[cnidaria]]ns ([[jellyfish]] and [[sea pen]]s).<ref name=":8" /> 580 Ma [[Gaskiers glaciation]], followed by rise in atmospheric oxygen levels.<ref name="GTS2012_Precambrian" /> [[Ediacaran biota]], deep water, soft-bodied organisms.<ref name=":14" /><ref name="GTS2012_Precambrian" /> First [[trace fossil]]s including simple burrows and first evidence of [[Bilateria|bilateral symmetry]].<ref name=":1" /> | ||
| style="background:{{period color|Ediacaran}}" |~{{Period start|ediacaran}} {{Period start error|ediacaran}}<sup>*</sup> | | style="background:{{period color|Ediacaran}}" |~{{Period start|ediacaran}} {{Period start error|ediacaran}}<sup>*</sup> | ||
|- | |- | ||
| style="background:{{period color|Cryogenian}}" |[[Cryogenian]] | | style="background:{{period color|Cryogenian}}" |[[Cryogenian]] | ||
| colspan="3" | | | colspan="3" |Rodinia continues to breakup. 720 Ma eruptions of [[Franklin Large Igneous Province|Franklin]] and Irkutsk LIPs mark rifting of Siberia from Laurentia. Iapetus Ocean begins to open as [[Amazonian Craton|Amazonia]] and Baltica drift from Laurentia (from c. 650 Ma).<ref name=":13" /> [[Sturtian glaciation|Sturtian]] (720–658 Ma) and [[Marinoan glaciation|Marinoan]] (655–635 Ma) [[Snowball Earth]] glaciations.<ref name="GTS2012_Precambrian" /> | ||
| style="background:{{period color|Cryogenian}}" |~{{Period start|cryogenian}} {{Period start error|cryogenian}} | | style="background:{{period color|Cryogenian}}" |~{{Period start|cryogenian}} {{Period start error|cryogenian}} | ||
|- | |- | ||
| style="background:{{period color|Tonian}}" |[[Tonian]] | | style="background:{{period color|Tonian}}" |[[Tonian]] | ||
| colspan="3" | | | colspan="3" |900 Ma Rodinia at its maximum extent. Intracontinental rifting begins c. 850 Ma, associated magmatism becoming widespread from 825 Ma, including the [[Jodhpur Group – Malani Igneous Suite Contact|Malani Igneous Suite]] eruptions, India (c. 775 Ma). Beginning of breakup of Rodinia from c. 750 Ma.<ref name=":13" /> | ||
| style="background:{{period color|Tonian}}" |{{Period start|tonian}} {{Period start error|tonian}}{{efn|name="absolute-age"|Defined by absolute age ([[Global Standard Stratigraphic Age]]).|group=note}} | | style="background:{{period color|Tonian}}" |{{Period start|tonian}} {{Period start error|tonian}}{{efn|name="absolute-age"|Defined by absolute age ([[Global Standard Stratigraphic Age]]).|group=note}} | ||
|- | |- | ||
| rowspan="3" style="background:{{period color|Mesoproterozoic}}" |[[Mesoproterozoic]] | | rowspan="3" style="background:{{period color|Mesoproterozoic}}" |[[Mesoproterozoic]] | ||
| style="background:{{period color|Stenian}}" |[[Stenian]] | | style="background:{{period color|Stenian}}" |[[Stenian]] | ||
| colspan="3" | | | colspan="3" |Collision between Laurentia and [[Amazonian Craton|Amazonia]] results in [[Grenville orogeny]] which, with [[Sveconorwegian orogeny]] in Baltica, mark beginning of assembly of [[Rodinia|Rodinian supercontinent]].<ref>{{Cite journal |last=Slagstad |first=Trond |last2=Roberts |first2=Nick M. W. |last3=Kulakov |first3=Evgeniy |date=2017-04-01 |title=Linking orogenesis across a supercontinent; the Grenvillian and Sveconorwegian margins on Rodinia |journal=Gondwana Research |volume=44 |pages=109–115 |doi=10.1016/j.gr.2016.12.007 }}</ref> Diversification of [[eukaryote]]s as oxygen levels increase. All major modern day [[clade]]s, including [[Archaeplastida]] (e.g. [[Red algae|red]] and [[green algae]]), [[Opisthokont]]a (e.g. [[Fungus|fungi]]) and [[Amoebozoa]] appear. Evidence for life on land.<ref name=":14" /><ref name="GTS2012_Precambrian" /> ''[[Bangiomorpha|Bangiomorpha pubescens]]'' (red algae) earliest known sexually reproducing organism.<ref>{{Cite journal |last=Gibson |first=Timothy M. |last2=Shih |first2=Patrick M. |last3=Cumming |first3=Vivien M. |last4=Fischer |first4=Woodward W. |last5=Crockford |first5=Peter W. |last6=Hodgskiss |first6=Malcolm S.W. |last7=Wörndle |first7=Sarah |last8=Creaser |first8=Robert A. |last9=Rainbird |first9=Robert H. |last10=Skulski |first10=Thomas M. |last11=Halverson |first11=Galen P. |date=2018-02-01 |title=Precise age of Bangiomorpha pubescens dates the origin of eukaryotic photosynthesis |url=http://pubs.geoscienceworld.org/gsa/geology/article/46/2/135/524864/Precise-age-of-Bangiomorpha-pubescens-dates-the |journal=Geology |language=en |volume=46 |issue=2 |pages=135–138 |doi=10.1130/G39829.1 |issn=0091-7613}}</ref> | ||
| style="background:{{period color|Stenian}}" |{{Period start|stenian}} {{Period start error|stenian}}{{efn|name="absolute-age"|group=note}} | | style="background:{{period color|Stenian}}" |{{Period start|stenian}} {{Period start error|stenian}}{{efn|name="absolute-age"|group=note}} | ||
|- | |- | ||
| style="background:{{period color|Ectasian}}" |[[Ectasian]] | | style="background:{{period color|Ectasian}}" |[[Ectasian]] | ||
| colspan="3" |[[ | | colspan="3" |Extensive dyke swarms found across all cratons mark completion of breakup of [[Columbia (supercontinent)|Columbia]] (Nuna) supercontinent.<ref>{{Cite journal |last=Mitchell |first=Ross N. |last2=Zhang |first2=Nan |last3=Salminen |first3=Johanna |last4=Liu |first4=Yebo |last5=Spencer |first5=Christopher J. |last6=Steinberger |first6=Bernhard |last7=Murphy |first7=J. Brendan |last8=Li |first8=Zheng-Xiang |date=2021 |title=The supercontinent cycle |url=https://www.nature.com/articles/s43017-021-00160-0 |journal=Nature Reviews Earth & Environment |language=en |volume=2 |issue=5 |pages=358–374 |doi=10.1038/s43017-021-00160-0 |issn=2662-138X}}</ref> Oceans have oxygen-rich surface layers and [[Euxinia|euxinic]] (no oxygen, high levels of H<sub>2</sub>S) deep waters, leading to widespread formation of giant [[Massive sulfide deposits|massive sulphide deposits]] (SEDEX) on the seafloor.<ref name="GTS2012_Precambrian" /> | ||
| style="background:{{period color|Ectasian}}" |{{Period start|ectasian}} {{Period start error|ectasian}}{{efn|name="absolute-age"|group=note}} | | style="background:{{period color|Ectasian}}" |{{Period start|ectasian}} {{Period start error|ectasian}}{{efn|name="absolute-age"|group=note}} | ||
|- | |- | ||
| style="background:{{period color|Calymmian}}" |[[Calymmian]] | | style="background:{{period color|Calymmian}}" |[[Calymmian]] | ||
| colspan="3" | | | colspan="3" |Columbia continues to fragment with widespread rift-related magmatism.<ref name=":16" /> Stromatolites reach their maximum extent and diversity as [[cyanobacteria]] diversify and flourish.<ref name=":14" /> Primitive seaweeds appear.<ref name="GTS2012_Precambrian" /> | ||
| style="background:{{period color|Calymmian}}" |{{Period start|calymmian}} {{Period start error|calymmian}}{{efn|name="absolute-age"|group=note}} | | style="background:{{period color|Calymmian}}" |{{Period start|calymmian}} {{Period start error|calymmian}}{{efn|name="absolute-age"|group=note}} | ||
|- | |- | ||
| rowspan="4" style="background:{{period color|Paleoproterozoic}}" |[[Paleoproterozoic]] | | rowspan="4" style="background:{{period color|Paleoproterozoic}}" |[[Paleoproterozoic]] | ||
| style="background:{{period color|Statherian}}" |[[Statherian]] | | style="background:{{period color|Statherian}}" |[[Statherian]] | ||
| colspan="3" | | | colspan="3" |Columbian supercontinent continues to grow along its margins by subduction-related magmatism and [[Terrane|terrane accretion]]. Extension and rift zones begin to develop from c. 1.6 Ga. Eukaryotic red algae appear.<ref name=":14" /> [[Vredefort impact structure|Vredefort impact event]] (2.19 Ga).<ref name=":15">{{cite journal |last1=Koeberl |first1=Christian |last2=Schulz |first2=Toni |last3=Huber |first3=Matthew S. |title=Precambrian impact structures and ejecta on earth: A review |journal=Precambrian Research |date=September 2024 |volume=411 |article-number=107511 |doi=10.1016/j.precamres.2024.107511 }}</ref> | ||
| style="background:{{period color|Statherian}}" |{{Period start|statherian}} {{Period start error|statherian}}{{efn|name="absolute-age"|group=note}} | | style="background:{{period color|Statherian}}" |{{Period start|statherian}} {{Period start error|statherian}}{{efn|name="absolute-age"|group=note}} | ||
|- | |- | ||
| style="background:{{period color|Orosirian}}" |[[Orosirian]] | | style="background:{{period color|Orosirian}}" |[[Orosirian]] | ||
| colspan="3" | | | colspan="3" |2.0–1.8 Ga Columbia supercontinent assembles during collisional events including [[Trans-Hudson orogeny]] (North America), [[Limpopo Belt]] (South Africa), [[Capricorn orogeny]] (Australia) and Trans-North China orogeny.<ref name=":16">{{Cite journal |last=Zhao |first=Guochun |last2=Li |first2=Sanzhong |last3=Sun |first3=Min |last4=Wilde |first4=Simon A. |date=2011 |title=Assembly, accretion, and break-up of the Palaeo-Mesoproterozoic Columbia supercontinent: record in the North China Craton revisited |url=https://www.tandfonline.com/doi/full/10.1080/00206814.2010.527631 |journal=International Geology Review |language=en |volume=53 |issue=11-12 |pages=1331–1356 |doi=10.1080/00206814.2010.527631 |issn=0020-6814}}</ref> Drop in atmospheric oxygen as increased volcanism releases carbon dioxide.<ref name="GTS2012_Precambrian" /> ''[[Grypania]]'' represents a possible early eukaryote.<ref name=":14" /> [[Sudbury Basin|Sudbury Impact]] (1.85 Ga).<ref name=":15" /> | ||
| style="background:{{period color|Orosirian}}" |{{Period start|orosirian}} {{Period start error|orosirian}}{{efn|name="absolute-age"|group=note}} | | style="background:{{period color|Orosirian}}" |{{Period start|orosirian}} {{Period start error|orosirian}}{{efn|name="absolute-age"|group=note}} | ||
|- | |- | ||
| style="background:{{period color|Rhyacian}}" |[[Rhyacian]] | | style="background:{{period color|Rhyacian}}" |[[Rhyacian]] | ||
| colspan="3" |[[ | | colspan="3" |Massive rise in atmospheric oxygen leads to expansion of life and increased burial of organic matter ([[Lomagundi-Jatuli Carbon Isotope Excursion|Lomagundi carbon isotope excursion]]) (2.3 to 2.1 Ga).<ref name=":14" /> First [[red beds]] deposited. Eruptions of [[Bushveld Igneous Complex|Bushveld Magmatic Province]] (from 2.25 Ga).<ref name="GTS2012_Precambrian" /> Orogenies in South America and West Africa mark beginning of Columbia supercontinent.<ref name=":16" /> [[Yarrabubba impact structure]] (c. 2.23 Ga).<ref name=":15" /> | ||
| style="background:{{period color|Rhyacian}}" |{{Period start|rhyacian}} {{Period start error|rhyacian}}{{efn|name="absolute-age"|group=note}} | | style="background:{{period color|Rhyacian}}" |{{Period start|rhyacian}} {{Period start error|rhyacian}}{{efn|name="absolute-age"|group=note}} | ||
|- | |- | ||
| style="background:{{period color|Siderian}}" |[[Siderian]] | | style="background:{{period color|Siderian}}" |[[Siderian]] | ||
| colspan="3" |[[ | | colspan="3" |2.5 – 2.42 Ga massive [[banded iron formation]]s (BIFs) precipitated across most continents.<ref name="GTS2012_Precambrian" /> Increasing atmospheric oxygen leads to [[Great Oxidation Event]] (c. 2.4––2.3 Ga) and [[Huronian glaciation]]s as global temperatures drop.<ref name=":14" /><ref name="GTS2012_Precambrian" /> | ||
| style="background:{{period color|Siderian}}" |{{Period start|siderian}} {{Period start error|siderian}}{{efn|name="absolute-age"|group=note}} | | style="background:{{period color|Siderian}}" |{{Period start|siderian}} {{Period start error|siderian}}{{efn|name="absolute-age"|group=note}} | ||
|- | |- | ||
| rowspan="4" style="background:{{period color|Archean}}" |[[Archean]] | | rowspan="4" style="background:{{period color|Archean}}" |[[Archean]] | ||
| style="background:{{period color|Neoarchean}}" |[[Neoarchean]] | | style="background:{{period color|Neoarchean}}" |[[Neoarchean]] | ||
| colspan="4" | | | colspan="4" |Widespread mantle melting and crustal growth followed by formation of supercratons [[Superior Craton|Superia]] (North America, northwest Europe, South Africa and northwest Australia) and [[Sclavia Craton|Sclavia]] (Canada, Zimbabwe, southern India, southwestern Australia, Brazil and North China).<ref name="GTS2012_Precambrian"/><ref>{{Cite journal |last=Liu |first=Jin |last2=Palin |first2=Richard M. |last3=Mitchell |first3=Ross N. |last4=Liu |first4=Zhenghong |last5=Zhang |first5=Jian |last6=Li |first6=Zhongshui |last7=Cheng |first7=Changquan |last8=Zhang |first8=Hongxiang |date=2024-07-24 |title=Archaean multi-stage magmatic underplating drove formation of continental nuclei in the North China Craton |url=https://pmc.ncbi.nlm.nih.gov/articles/PMC11266541/ |journal=Nature Communications |volume=15 |issue=1 |page=6231 |doi=10.1038/s41467-024-50435-5 |issn=2041-1723 |pmc=11266541 |pmid=39043649}}</ref> Major diversification of cyanobacteria with multicellularity, increasing cell size and specialisation.<ref name=":14" /> Proliferation of oxygen-producing life leads to stepwise increase in atmospheric oxygen and deposition of banded iron formation.<ref name=":14" /><ref name="GTS2012_Precambrian"/> | ||
| style="background:{{period color|Neoarchean}}" |{{Period start|neoarchean}} {{Period start error|neoarchean}}{{efn|name="absolute-age"|group=note}} | | style="background:{{period color|Neoarchean}}" |{{Period start|neoarchean}} {{Period start error|neoarchean}}{{efn|name="absolute-age"|group=note}} | ||
|- | |- | ||
| style="background:{{period color|Mesoarchean}}" |[[Mesoarchean]] | | style="background:{{period color|Mesoarchean}}" |[[Mesoarchean]] | ||
| colspan="4" | | | colspan="4" |Possible onset of plate tectonics c. 3 Ga.<ref name="Torsvik_Cocks 2017" /> Cratons with low relief and extensive shallow marine environments. Weathering increased supply of nutrients to seas. Localised free oxygen associated with carbonate platform stromatolites. Evidence for oxygen-producing [[Photoautotroph|photosynthesisers]] (and possible eukaryotes) c. 3.2 Ga, and terrestrial life c. 3 Ga.<ref name=":14" /> Oldest evidence of glaciation c. 2.9 Ga.<ref name="GTS2012_Precambrian"/> | ||
| style="background:{{period color|Mesoarchean}}" |{{Period start|mesoarchean}} {{Period start error|mesoarchean}}{{efn|name="absolute-age"|group=note}} | | style="background:{{period color|Mesoarchean}}" |{{Period start|mesoarchean}} {{Period start error|mesoarchean}}{{efn|name="absolute-age"|group=note}} | ||
|- | |- | ||
| style="background:{{period color|Paleoarchean}}" |[[Paleoarchean]] | | style="background:{{period color|Paleoarchean}}" |[[Paleoarchean]] | ||
| colspan="4" | | | colspan="4" |Growth of cratons by terrane accretion.<ref name="GTS2012_Precambrian"/> Oldest evidence for [[Macroscopic scale|macroscopic life]] preserved as stromatolites (c. 3.4 Ga). Evidence for [[Anaerobic organism|anaerobic]] [[prokaryote]]s in variety of environments including [[Hydrothermal circulation|hydrothermal systems]] and within subsurface sediments. [[Microbial mat]]s and [[biofilm]]s become common in shallow water environments.<ref name=":14" /> | ||
| style="background:{{period color|Paleoarchean}}" |{{Period start|paleoarchean}} {{Period start error|paleoarchean}}{{efn|name="absolute-age"|group=note}} | | style="background:{{period color|Paleoarchean}}" |{{Period start|paleoarchean}} {{Period start error|paleoarchean}}{{efn|name="absolute-age"|group=note}} | ||
|- | |- | ||
| style="background:{{period color|Eoarchean}}" |[[Eoarchean]] | | style="background:{{period color|Eoarchean}}" |[[Eoarchean]] | ||
| colspan="4" | | | colspan="4" |Increasing formation of [[continental crust]].<ref name="GTS2012_Precambrian"/> 3.8 – 3.65 Ga chemical traces of life in earliest known sedimentary rocks ([[Isua Greenstone Belt]]). Anaerobic prokaryotes including [[chemotroph]]s and photosynthesisers appear from c. 3.7 Ga. Early BIFs due to [[anoxygenic photosynthesis]].<ref name=":14" /> | ||
| style="background:{{period color|Eoarchean}}" |{{Period start|eoarchean}} {{Period start error|eoarchean}}{{efn|name="absolute-age"|group=note}} | | style="background:{{period color|Eoarchean}}" |{{Period start|eoarchean}} {{Period start error|eoarchean}}{{efn|name="absolute-age"|group=note}} | ||
|- | |- | ||
| style="background:{{period color|Hadean}}" |[[Hadean]] | | style="background:{{period color|Hadean}}" |[[Hadean]] | ||
| colspan="5" |Formation of [[ | | colspan="5" |Earth consolidates from [[Formation and evolution of the Solar System|solar nebula]] over 10-30 million years. Collision with [[Theia (hypothetical planet)|Theia]] (proto-planet) forms [[Moon]] from debris. [[Internal structure of Earth|Core]] differentiates. [[Magma ocean]] cools, releasing CO<sub>2</sub> and water to give CO<sub>2</sub>-rich atmosphere. Icy [[asteroid]]s also contribute water.<ref name="GTS2012_Precambrian" /> [[Mantle convection]] begins with rapid, shallow [[plate tectonics]] or [[Lid tectonics|stagnant lid tectonics]]. Decline in [[meteorite]] impacts with last ocean-vaporising impact c. 4.3 Ga. Probable emergence of life after this.<ref name=":14">{{cite journal |last1=Westall |first1=Frances |last2=Xiao |first2=Shuhai |title=Precambrian Earth: Co-evolution of life and geodynamics |journal=Precambrian Research |date=November 2024 |volume=414 |article-number=107589 |doi=10.1016/j.precamres.2024.107589 }}</ref> Evidence for oldest [[Earth's crust|crust]] from [[Detrital zircon geochronology|detrital zircon]] c. 4.37 Ga.<ref name="Torsvik_Cocks 2017" /><ref name="GTS2012_Precambrian"/> [[Acasta Gneiss|Acasta gneiss complex]] contains oldest recorded rocks c. 4.03 Ga.<ref name="GTS2012_Precambrian"/> | ||
| style="background:{{period color|Hadean}}" |{{Period start|hadean}} {{Period start error|hadean}}{{efn|name="absolute-age"|group=note}} | | style="background:{{period color|Hadean}}" |{{Period start|hadean}} {{Period start error|hadean}}{{efn|name="absolute-age"|group=note}} | ||
|} | |} | ||
== | == Major proposed revisions to the ICC == | ||
{{Main|Lunar geologic timescale|Martian geologic timescale|Geology of Venus}}Some other [[Planet#Solar System|planets]] and [[Natural satellite|satellites]] in the [[Solar System]] have sufficiently rigid structures to have preserved records of their own histories, for example, [[Geology of Venus|Venus]], [[Geology of Mars|Mars]] and the Earth's [[Moon]]. Dominantly fluid planets, such as the [[giant planet]]s, do not comparably preserve their history. 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. 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. The existence, timing, and terrestrial effects of the Late Heavy Bombardment are still a matter of debate.{{ | === Proposed Anthropocene Series/Epoch === | ||
{{Main|Anthropocene}} | |||
First suggested in 2000,<ref name="Crutzen_2021">{{cite book |last1=Crutzen |first1=Paul J. |last2=Stoermer |first2=Eugene F. |title=Paul J. Crutzen and the Anthropocene: A New Epoch in Earth's History |chapter=The 'Anthropocene' (2000) |series=The Anthropocene: Politik—Economics—Society—Science |date=2021 |volume=1 |pages=19–21 |doi=10.1007/978-3-030-82202-6_2 |isbn=978-3-030-82201-9 }}</ref> the ''Anthropocene'' is a proposed epoch/series for the most recent time in Earth's history. While still informal, it is a widely used term to denote the present geologic time interval, in which many conditions and processes on Earth are profoundly altered by human impact.<ref>{{Cite web |title=Working Group on the 'Anthropocene' {{!}} Subcommission on Quaternary Stratigraphy |url=https://quaternary.stratigraphy.org/working-groups/anthropocene/ |archive-url=https://web.archive.org/web/20220407193255/https://quaternary.stratigraphy.org/working-groups/anthropocene/ |archive-date=2022-04-07 |access-date=2022-04-17 |language=en-US}}</ref> The definition of the Anthropocene as a geologic time period rather than a geologic event remains controversial and difficult.<ref name="Gibbard_2021">{{cite journal |last1=Gibbard |first1=Philip L. |last2=Bauer |first2=Andrew M. |last3=Edgeworth |first3=Matthew |last4=Ruddiman |first4=William F. |last5=Gill |first5=Jacquelyn L. |last6=Merritts |first6=Dorothy J. |last7=Finney |first7=Stanley C. |last8=Edwards |first8=Lucy E. |last9=Walker |first9=Michael J. C. |last10=Maslin |first10=Mark |last11=Ellis |first11=Erle C. |title=A practical solution: the Anthropocene is a geological event, not a formal epoch |journal=Episodes |date=December 2022 |volume=45 |issue=4 |pages=349–357 |doi=10.18814/epiiugs/2021/021029 |bibcode=2021Episo..45..349G |doi-access=free }}</ref><ref name="Head_2021">{{cite journal |last1=Head |first1=Martin J. |last2=Steffen |first2=Will |last3=Fagerlind |first3=David |last4=Waters |first4=Colin N. |last5=Poirier |first5=Clement |last6=Syvitski |first6=Jaia |last7=Zalasiewicz |first7=Jan A. |last8=Barnosky |first8=Anthony D. |last9=Cearreta |first9=Alejandro |last10=Jeandel |first10=Catherine |last11=Leinfelder |first11=Reinhold |last12=McNeill |first12=J.R. |last13=Rose |first13=Neil L. |last14=Summerhayes |first14=Colin |last15=Wagreich |first15=Michael |last16=Zinke |first16=Jens |title=The Great Acceleration is real and provides a quantitative basis for the proposed Anthropocene Series/Epoch |journal=Episodes |date=December 2022 |volume=45 |issue=4 |pages=359–376 |doi=10.18814/epiiugs/2021/021031 |doi-access=free }}</ref><ref name="Zalasiewicz_2021">{{Cite journal |last1=Zalasiewicz |first1=Jan |last2=Waters |first2=Colin N. |last3=Ellis |first3=Erle C. |last4=Head |first4=Martin J. |last5=Vidas |first5=Davor |last6=Steffen |first6=Will |last7=Thomas |first7=Julia Adeney |last8=Horn |first8=Eva |last9=Summerhayes |first9=Colin P. |last10=Leinfelder |first10=Reinhold |last11=McNeill |first11=J. R. |date=2021 |title=The Anthropocene: Comparing Its Meaning in Geology (Chronostratigraphy) with Conceptual Approaches Arising in Other Disciplines |journal=Earth's Future |volume=9 |issue=3 |article-number=e2020EF001896 |doi=10.1029/2020EF001896 |bibcode=2021EaFut...901896Z |doi-access=free }}</ref><ref name="Bauer_2021">{{cite journal |last1=Bauer |first1=Andrew M. |last2=Edgeworth |first2=Matthew |last3=Edwards |first3=Lucy E. |last4=Ellis |first4=Erle C. |last5=Gibbard |first5=Philip |last6=Merritts |first6=Dorothy J. |title=Anthropocene: event or epoch? |journal=Nature |date=16 September 2021 |volume=597 |issue=7876 |page=332 |doi=10.1038/d41586-021-02448-z |pmid=34522014 |bibcode=2021Natur.597..332B }}</ref> | |||
In May 2019 the [[Anthropocene Working Group]] voted in favour of submitting a formal proposal to the ICS for the establishment of the Anthropocene Series/Epoch.<ref name="Subramanian_2019">{{cite journal |last1=Subramanian |first1=Meera |title=Anthropocene now: influential panel votes to recognize Earth's new epoch |journal=Nature |date=21 May 2019 |doi=10.1038/d41586-019-01641-5 |pmid=32433629 }}</ref> The formal proposal was completed and submitted to the Subcommission on Quaternary Stratigraphy in late 2023 for a section in [[Crawford Lake (Halton Region)|Crawford Lake]], [[Ontario]], with heightened Plutonium levels corresponding to 1952 CE.<ref>{{cite web |title=Working Group on the 'Anthropocene' |url=https://quaternary.stratigraphy.org/working-groups/anthropocene |website=Subcommission on Quaternary Stratigraphy |publisher=International Commission on Stratigraphy |access-date=23 October 2025}}</ref> This proposal was rejected as a formal geologic epoch in early 2024, to be left instead as an "invaluable descriptor of human impact on the Earth system"<ref>{{cite web |title=Joint statement by the IUGS and ICS on the vote by the ICS Subcommission on Quaternary Stratigraphy |url=https://stratigraphy.org/news/152 |website=International Commission on Stratigraphy |access-date=23 October 2025}}</ref> | |||
=== Proposals for revisions to pre-Cryogenian timeline === | |||
==== Shields et al. 2021 ==== | |||
The ICS Subcommission for Cryogenian Stratigraphy has outlined a template to improve the pre-Cryogenian geologic time scale based on the rock record to bring it in line with the post-Tonian geologic time scale.<ref name="Shields_2022_pre-Cryogenian" /> This work assessed the geologic history of the currently defined eons and eras of the Precambrian,{{Efn|name=Precam|group=note}} and the proposals in the "Geological Time Scale" books ''2004,''<ref name="GTS2004_Precambrian">{{cite book |last1=Bleeker |first1=W. |title=A Geologic Time Scale 2004 |chapter=Toward a 'natural' Precambrian time scale |date=2005 |pages=141–146 |doi=10.1017/cbo9780511536045.011 |isbn=978-0-521-78673-7 }}</ref> ''2012,''<ref name="GTS2012_Precambrian" /> and ''2020.''<ref name="GTS2020_Precambrian">{{cite book |last1=Strachan |first1=R. |last2=Murphy |first2=J.B. |last3=Darling |first3=J. |last4=Storey |first4=C. |last5=Shields |first5=G. |title=Geologic Time Scale 2020 |chapter=Precambrian (4.56–1 Ga) |date=2020 |pages=481–493 |doi=10.1016/b978-0-12-824360-2.00016-4 |isbn=978-0-12-824360-2 }}</ref> Their recommend revisions<ref name="Shields_2022_pre-Cryogenian" /> of the pre-Cryogenian geologic time scale were as below (changes from the current scale [v2023/09] are italicised). This suggestion was unanimously rejected by the International Subcommission for Precambrian Stratigraphy, based on scientific weaknesses. | |||
* Three divisions of the Archean instead of four by dropping Eoarchean, and revisions to their geochronometric definition, along with the repositioning of the Siderian into the latest Neoarchean, and a potential Kratian division in the Neoarchean. | |||
** Archean (4000–''2450'' Ma) | |||
*** Paleoarchean (4000–''3500'' Ma) | |||
*** Mesoarchean (''3500–3000'' Ma) | |||
*** Neoarchean (''3000–2450'' Ma) | |||
**** ''Kratian'' (no fixed time given, prior to the Siderian) – from Greek κράτος (''krátos'') 'strength'. | |||
**** Siderian (?–''2450'' Ma) – moved from Proterozoic to end of Archean, no start time given, base of Paleoproterozoic defines the end of the Siderian | |||
* Refinement of geochronometric divisions of the Proterozoic, Paleoproterozoic, repositioning of the Statherian into the Mesoproterozoic, new Skourian period/system in the Paleoproterozoic, new Kleisian or Syndian period/system in the Neoproterozoic. | |||
** Paleoproterozoic (''2450–1800'' Ma) | |||
*** ''Skourian'' (''2450''–2300 Ma) – from Greek σκουριά (''skouriá'') 'rust'. | |||
*** Rhyacian (2300–2050 Ma) | |||
*** Orosirian (2050–1800 Ma) | |||
** Mesoproterozoic (''1800''–1000 Ma) | |||
*** ''Statherian'' (1800–1600 Ma) | |||
*** Calymmian (1600–1400 Ma) | |||
*** Ectasian (1400–1200 Ma) | |||
*** Stenian (1200–1000 Ma) | |||
** Neoproterozoic (1000–538.8 Ma){{Efn|Geochronometric date for the Ediacaran has been adjusted to reflect ICC v2023/09 as the formal definition for the base of the Cambrian has not changed.|name=EdiacaranDate|group=note}} | |||
*** ''Kleisian'' or ''Syndian'' (''1000–800'' Ma) – respectively from Greek κλείσιμο (''kleísimo'') 'closure' and σύνδεση (''sýndesi'') 'connection'. | |||
*** Tonian (''800''–720 Ma) | |||
*** Cryogenian (720–635 Ma) | |||
*** Ediacaran (635–538.8 Ma) | |||
Proposed pre-Cambrian timeline (Shield et al. 2021, ICS working group on pre-Cryogenian chronostratigraphy), shown to scale:{{Efn|Kratian time span is not given in the article. It lies within the Neoarchean, and prior to the Siderian. The position shown here is an arbitrary division.|name=kratian|group=note}} | |||
<timeline> | |||
ImageSize = width:1300 height:100 | |||
PlotArea = left:80 right:20 bottom:20 top:5 | |||
AlignBars = justify | |||
Colors = | |||
id:proterozoic value:rgb(0.968,0.207,0.388) | |||
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:kleisian value:rgb(0.996,0.773,0.431) | |||
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:skourian value:rgb(0.949,0.439,0.545) | |||
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: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:hadean value:rgb(0.717,0,0.494) | |||
id:black value:black | |||
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 = | |||
align:center textcolor:black fontsize:8 mark:(line,black) width:25 shift:(0,-5) | |||
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 | |||
</timeline> | |||
ICC pre-Cambrian timeline (v2024/12, current {{As of|2025|01|lc=y}}), shown to scale: | |||
<timeline> | |||
ImageSize = width:1300 height:100 | |||
PlotArea = left:80 right:20 bottom:20 top:5 | |||
AlignBars = justify | |||
Colors = | |||
id:proterozoic value:rgb(0.968,0.207,0.388) | |||
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 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: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 | |||
</timeline> | |||
==== Van Kranendonk et al. 2012 (GTS2012) ==== | |||
The book, ''Geologic Time Scale 2012,'' was the last commercial publication of an international chronostratigraphic chart that was closely associated with the ICS and the Subcommission on Precambrian Stratigraphy.<ref name="ICS" /> It included a proposal to substantially revise the pre-Cryogenian time scale to reflect important events such as the [[Formation and evolution of the Solar System|formation of the Solar System]] and the [[Great Oxidation Event]], among others, while at the same time maintaining most of the previous chronostratigraphic nomenclature for the pertinent time span.<ref name="GTS2012_Precambrian"/> {{As of|2022|April}} these proposed changes have not been accepted by the ICS. The proposed changes (changes from the current scale [v2023/09]) are italicised: | |||
* Hadean Eon (4567''–4030'' Ma) | |||
** [[Chaotian (geology)|''Chaotian'']] Era/Erathem (''4567–4404'' Ma) – the name alluding both to the [[Chaos (cosmogony)|mythological Chaos]] and the chaotic phase of [[planet formation]].<ref name="GTS2012" /><ref name="Goldblatt_2010">{{cite journal |last1=Goldblatt |first1=C. |last2=Zahnle |first2=K. J. |last3=Sleep |first3=N. H. |last4=Nisbet |first4=E. G. |date=2010 |title=The Eons of Chaos and Hades |journal=Solid Earth |volume=1 |issue=1 |pages=1–3 |bibcode=2010SolE....1....1G |doi=10.5194/se-1-1-2010 |doi-access=free}}</ref><ref>{{cite journal |last=Chambers |first=John E. |date=July 2004 |title=Planetary accretion in the inner Solar System |url=http://www.astro.washington.edu/courses/astro321/Chambers_EPSL_04.pdf |archive-url=https://web.archive.org/web/20120419024812/http://www.astro.washington.edu/courses/astro321/Chambers_EPSL_04.pdf |archive-date=2012-04-19 |url-status=live |journal=Earth and Planetary Science Letters |volume=223 |issue=3–4 |pages=241–252 |bibcode=2004E&PSL.223..241C |doi=10.1016/j.epsl.2004.04.031}}</ref> | |||
** ''Jack Hillsian'' or ''Zirconian'' Era/Erathem (''4404–4030'' Ma) – both names allude to the Jack Hills Greenstone Belt which provided the oldest mineral grains on Earth, [[zircon]]s.<ref name="GTS2012" /><ref name="Goldblatt_2010" /> | |||
* Archean Eon/Eonothem (''4030–2420'' Ma) | |||
** Paleoarchean Era/Erathem (''4030–3490'' Ma) | |||
*** ''Acastan'' Period/System (''4030–3810'' Ma) – named after the [[Acasta Gneiss]], one of the oldest preserved pieces of [[continental crust]].<ref name="GTS2012" /><ref name="Goldblatt_2010" /> | |||
*** ''Isuan'' Period/System (''3810–3490'' Ma) – named after the [[Isua Greenstone Belt]].<ref name="GTS2012" /> | |||
** Mesoarchean Era/Erathem (''3490–2780'' Ma) | |||
*** ''Vaalbaran'' Period/System (''3490–3020'' Ma) – based on the names of the [[Kaapvaal craton|Kaapvaal]] (Southern Africa) and [[Pilbara craton|Pilbara]] (Western Australia) [[craton]]s, to reflect the growth of stable continental nuclei or proto-[[craton]]ic kernels.<ref name="GTS2012" /> | |||
*** ''Pongolan'' Period/System (''3020–2780'' Ma) – named after the Pongola Supergroup, in reference to the well preserved evidence of terrestrial microbial communities in those rocks.<ref name="GTS2012" /> | |||
** Neoarchean Era/Erathem (''2780–2420'' Ma) | |||
*** ''Methanian'' Period/System (''2780–2630'' Ma) – named for the inferred predominance of [[methanotrophic]] [[prokaryote]]s<ref name="GTS2012" /> | |||
*** Siderian Period/System (''2630–2420'' Ma) – named for the voluminous [[banded iron formation]]s formed within its duration.<ref name="GTS2012" /> | |||
* Proterozoic Eon/Eonothem (''2420''–538.8 Ma){{efn|name=EdiacaranDate|group=note}} | |||
** Paleoproterozoic Era/Erathem (''2420–1780'' Ma) | |||
*** ''Oxygenian'' Period/System (''2420–2250'' Ma) – named for displaying the first evidence for a global oxidising atmosphere.<ref name="GTS2012" /> | |||
*** ''Jatulian'' or ''Eukaryian'' Period/System (''2250–2060'' Ma) – names are respectively for the Lomagundi–Jatuli δ<sup>13</sup>C isotopic excursion event spanning its duration, and for the (proposed)<ref name="El_Albani_2014">{{cite journal |last1=El Albani |first1=Abderrazak |last2=Bengtson |first2=Stefan |last3=Canfield |first3=Donald E. |last4=Riboulleau |first4=Armelle |last5=Rollion Bard |first5=Claire |last6=Macchiarelli |first6=Roberto |display-authors=etal |year=2014 |title=The 2.1 Ga Old Francevillian Biota: Biogenicity, Taphonomy and Biodiversity |journal=PLOS ONE |volume=9 |issue=6 |article-number=e99438 |bibcode=2014PLoSO...999438E |doi=10.1371/journal.pone.0099438 |pmc=4070892 |pmid=24963687 |doi-access=free}}</ref><ref name="El_Albani_2010">{{cite journal |last1=Albani |first1=Abderrazak El |last2=Bengtson |first2=Stefan |last3=Canfield |first3=Donald E. |last4=Bekker |first4=Andrey |last5=Macchiarelli |first5=Roberto |last6=Mazurier |first6=Arnaud |last7=Hammarlund |first7=Emma U. |last8=Boulvais |first8=Philippe |last9=Dupuy |first9=Jean-Jacques |last10=Fontaine |first10=Claude |last11=Fürsich |first11=Franz T. |last12=Gauthier-Lafaye |first12=François |last13=Janvier |first13=Philippe |last14=Javaux |first14=Emmanuelle |last15=Ossa |first15=Frantz Ossa |last16=Pierson-Wickmann |first16=Anne-Catherine |last17=Riboulleau |first17=Armelle |last18=Sardini |first18=Paul |last19=Vachard |first19=Daniel |last20=Whitehouse |first20=Martin |last21=Meunier |first21=Alain |title=Large colonial organisms with coordinated growth in oxygenated environments 2.1 Gyr ago |journal=Nature |date=July 2010 |volume=466 |issue=7302 |pages=100–104 |doi=10.1038/nature09166 |pmid=20596019 |bibcode=2010Natur.466..100A }}</ref> first fossil appearance of [[eukaryote]]s.<ref name="GTS2012" /> | |||
*** ''Columbian Period/System'' (''2060–1780'' Ma) – named after the [[supercontinent]] [[Columbia (supercontinent)|Columbia]].<ref name="GTS2012" /> | |||
** Mesoproterozoic Era/Erathem (''1780–850'' Ma) | |||
*** ''Rodinian'' Period/System (''1780–850'' Ma) – named after the supercontinent [[Rodinia]], stable environment.<ref name="GTS2012" /> | |||
Proposed pre-Cambrian timeline (GTS2012), shown to scale: | |||
<timeline> | |||
ImageSize = width:1200 height:100 | |||
PlotArea = left:80 right:20 bottom:20 top:5 | |||
AlignBars = justify | |||
Colors = | |||
id:proterozoic value:rgb(0.968,0.207,0.388) | |||
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: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) | |||
id:neoarchean value:rgb(0.976,0.608,0.757) | |||
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) | |||
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: -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 | |||
</timeline> | |||
ICC pre-Cambrian timeline (v2024/12, current {{As of|2025|01|lc=y}}), shown to scale: | |||
<timeline> | |||
ImageSize = width:1200 height:100 | |||
PlotArea = left:80 right:20 bottom:20 top:5 | |||
AlignBars = justify | |||
Colors = | |||
id:proterozoic value:rgb(0.968,0.207,0.388) | |||
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 | |||
</timeline> | |||
== Extraterrestrial geologic time scales == | |||
{{Main|Lunar geologic timescale|Martian geologic timescale|Geology of Venus}} | |||
Some other [[Planet#Solar System|planets]] and [[Natural satellite|satellites]] in the [[Solar System]] have sufficiently rigid structures to have preserved records of their own histories, for example, [[Geology of Venus|Venus]], [[Geology of Mars|Mars]] and the Earth's [[Moon]]. Dominantly fluid planets, such as the [[giant planet]]s, do not comparably preserve their history. 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. 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. The existence, timing, and terrestrial effects of the Late Heavy Bombardment are still a matter of debate.{{citation needed|date=April 2026}} | |||
=== Lunar (selenological) time scale === | === Lunar (selenological) time scale === | ||
The [[Geology of the Moon|geologic history]] of Earth's Moon has been divided into a time scale based on [[Geomorphology|geomorphological]] markers, namely [[impact crater]]ing, [[volcanism]], and [[erosion]]. This process of dividing the Moon's history in this manner means that the time scale boundaries do not imply fundamental changes in geological processes, unlike Earth's geologic time scale. Five geologic systems/periods ([[Pre-Nectarian]], [[Nectarian]], [[Imbrian]], [[Eratosthenian]], [[Copernican period|Copernican]]), with the Imbrian divided into two series/epochs (Early and Late) were defined in the latest Lunar geologic time scale.<ref name="Wilhelms_1987">{{Cite book |last=Wilhelms |first=Don E. |title=The geologic history of the Moon |series=Professional Paper |publisher=United States Geological Survey |year=1987 |doi=10.3133/pp1348}}</ref> The Moon is unique in the Solar System in that it is the only other body from which humans have rock samples with a known geological context. | The [[Geology of the Moon|geologic history]] of Earth's Moon has been divided into a time scale based on [[Geomorphology|geomorphological]] markers, namely [[impact crater]]ing, [[volcanism]], and [[erosion]]. This process of dividing the Moon's history in this manner means that the time scale boundaries do not imply fundamental changes in geological processes, unlike Earth's geologic time scale. Five geologic systems/periods ([[Pre-Nectarian]], [[Nectarian]], [[Imbrian]], [[Eratosthenian]], [[Copernican period|Copernican]]), with the Imbrian divided into two series/epochs (Early and Late) were defined in the latest Lunar geologic time scale.<ref name="Wilhelms_1987">{{Cite book |last=Wilhelms |first=Don E. |title=The geologic history of the Moon |series=Professional Paper |publisher=United States Geological Survey |year=1987 |doi=10.3133/pp1348 |bibcode=1987ghm..book.....W }}</ref> The Moon is unique in the Solar System in that it is the only other body from which humans have rock samples with a known geological context. | ||
{{Timeline Lunar Geological Timescale}} | {{Timeline Lunar Geological Timescale}} | ||
=== Martian geologic time scale === | === Martian geologic time scale === | ||
The [[geological history of Mars]] has been divided into two alternate time scales. The first time scale for Mars was developed by studying the impact crater densities on the Martian surface. Through this method four periods have been defined, the Pre-Noachian (~4,500–4,100 Ma), Noachian (~4,100–3,700 Ma), Hesperian (~3,700–3,000 Ma), and Amazonian (~3,000 Ma to present).<ref name="Tanaka_1986">{{ | The [[geological history of Mars]] has been divided into two alternate time scales. The first time scale for Mars was developed by studying the impact crater densities on the Martian surface. Through this method four periods have been defined, the Pre-Noachian (~4,500–4,100 Ma), Noachian (~4,100–3,700 Ma), Hesperian (~3,700–3,000 Ma), and Amazonian (~3,000 Ma to present).<ref name="Tanaka_1986">{{cite journal |last1=Tanaka |first1=Kenneth L. |title=The stratigraphy of Mars |journal=Journal of Geophysical Research: Solid Earth |date=30 November 1986 |volume=91 |issue=B13 |doi=10.1029/JB091iB13p0E139 |bibcode=1986JGR....91E.139T }}</ref><ref name="Carr_2010">{{cite journal |last1=Carr |first1=Michael H. |last2=Head |first2=James W. |title=Geologic history of Mars |journal=Earth and Planetary Science Letters |date=June 2010 |volume=294 |issue=3–4 |pages=185–203 |doi=10.1016/j.epsl.2009.06.042 |bibcode=2010E&PSL.294..185C }}</ref> | ||
{{Mars timescale}} | {{Mars timescale}} | ||
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).<ref name="Bibring_2006">{{ | 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).<ref name="Bibring_2006">{{cite journal |last1=Bibring |first1=Jean-Pierre |last2=Langevin |first2=Yves |last3=Mustard |first3=John F. |last4=Poulet |first4=François |last5=Arvidson |first5=Raymond |last6=Gendrin |first6=Aline |last7=Gondet |first7=Brigitte |last8=Mangold |first8=Nicolas |last9=Pinet |first9=P. |last10=Forget |first10=F. |last11=Berthé |first11=Michel |last12=Bibring |first12=Jean-Pierre |last13=Gendrin |first13=Aline |last14=Gomez |first14=Cécile |last15=Gondet |first15=Brigitte |last16=Jouglet |first16=Denis |last17=Poulet |first17=François |last18=Soufflot |first18=Alain |last19=Vincendon |first19=Mathieu |last20=Combes |first20=Michel |last21=Drossart |first21=Pierre |last22=Encrenaz |first22=Thérèse |last23=Fouchet |first23=Thierry |last24=Merchiorri |first24=Riccardo |last25=Belluci |first25=GianCarlo |last26=Altieri |first26=Francesca |last27=Formisano |first27=Vittorio |last28=Capaccioni |first28=Fabricio |last29=Cerroni |first29=Pricilla |last30=Coradini |first30=Angioletta |last31=Fonti |first31=Sergio |last32=Korablev |first32=Oleg |last33=Kottsov |first33=Volodia |last34=Ignatiev |first34=Nikolai |last35=Moroz |first35=Vassili |last36=Titov |first36=Dimitri |last37=Zasova |first37=Ludmilla |last38=Loiseau |first38=Damien |last39=Mangold |first39=Nicolas |last40=Pinet |first40=Patrick |last41=Douté |first41=Sylvain |last42=Schmitt |first42=Bernard |last43=Sotin |first43=Christophe |last44=Hauber |first44=Ernst |last45=Hoffmann |first45=Harald |last46=Jaumann |first46=Ralf |last47=Keller |first47=Uwe |last48=Arvidson |first48=Ray |last49=Mustard |first49=John F. |last50=Duxbury |first50=Tom |last51=Forget |first51=François |last52=Neukum |first52=G. |title=Global Mineralogical and Aqueous Mars History Derived from OMEGA/Mars Express Data |journal=Science |date=21 April 2006 |volume=312 |issue=5772 |pages=400–404 |doi=10.1126/science.1122659 |pmid=16627738 |bibcode=2006Sci...312..400B }}</ref> | ||
<timeline> | <timeline> | ||
ImageSize = width:800 height:50 | ImageSize = width:800 height:50 | ||
| Line 1,335: | Line 945: | ||
{{Portal|Geology}} | {{Portal|Geology}} | ||
{{div col|colwidth=25em}} | {{div col|colwidth=25em}} | ||
* [[Cosmic calendar]] | * [[Cosmic calendar]] | ||
* [[Deep time]] | * [[Deep time]] | ||
* [[Evolutionary history of life]] | * [[Evolutionary history of life]] | ||
* [[Formation and evolution of the Solar System]] | * [[Formation and evolution of the Solar System]] | ||
* [[Geology of Mars]] | * [[Geology of Mars]] | ||
* [[Geon (geology)]] | * [[Geon (geology)]] | ||
| Line 1,346: | Line 954: | ||
* [[History of geology]] | * [[History of geology]] | ||
* [[History of paleontology]] | * [[History of paleontology]] | ||
* [[List of geochronologic names]] | * [[List of geochronologic names]] | ||
* [[Natural history]] | * [[Natural history]] | ||
* [[New Zealand geologic time scale]] | * [[New Zealand geologic time scale]] | ||
| Line 1,369: | Line 974: | ||
==Further reading== | ==Further reading== | ||
* {{cite journal |date=2009 |last1=Aubry|first1=Marie-Pierre|last2=Van Couvering|first2=John A.|last3=Christie-Blick|first3=Nicholas|last4= Landing|first4=Ed|last5=Pratt|first5=Brian R.|last6=Owen|first6=Donald E.|last7=Ferrusquia-Villafranca|first7=Ismael |title=Terminology of geological time: Establishment of a community standard |journal=Stratigraphy |volume=6 |issue=2 |pages=100–105 |doi=10.7916/D8DR35JQ}} | * {{cite journal |date=2009 |last1=Aubry|first1=Marie-Pierre|last2=Van Couvering|first2=John A.|last3=Christie-Blick|first3=Nicholas|last4= Landing|first4=Ed|last5=Pratt|first5=Brian R.|last6=Owen|first6=Donald E.|last7=Ferrusquia-Villafranca|first7=Ismael |title=Terminology of geological time: Establishment of a community standard |journal=Stratigraphy |volume=6 |issue=2 |pages=100–105 |doi=10.7916/D8DR35JQ}} | ||
* {{cite journal | * {{cite journal |last1=Gradstein |first1=Felix M. |last2=Ogg |first2=James G. |title=Geologic Time Scale 2004 – why, how, and where next! |journal=Lethaia |date=June 2004 |volume=37 |issue=2 |pages=175–181 |doi=10.1080/00241160410006483 |bibcode=2004Letha..37..175G }} | ||
* {{cite book | | * {{cite book |editor-first1=Felix M. |editor-first2=James G. |editor-first3=Alan G. |editor-last1=Gradstein |editor-last2=Ogg |editor-last3=Smith |title=A Geologic Time Scale 2004 |date=2005 |doi=10.1017/CBO9780511536045 |isbn=978-0-521-78673-7 }} | ||
* {{cite journal |date=June 2004 |last1=Gradstein |first1=Felix M. |last2=Ogg |first2=James G. |last3=Smith |first3=Alan G. |last4=Bleeker |first4=Wouter |last5=Laurens |first5=Lucas, J. |title=A new Geologic Time Scale, with special reference to Precambrian and Neogene |journal=Episodes |volume=27 |issue=2 |pages=83–100 |doi=10.18814/epiiugs/2004/v27i2/002 |doi-access=free }} | * {{cite journal |date=June 2004 |last1=Gradstein |first1=Felix M. |last2=Ogg |first2=James G. |last3=Smith |first3=Alan G. |last4=Bleeker |first4=Wouter |last5=Laurens |first5=Lucas, J. |title=A new Geologic Time Scale, with special reference to Precambrian and Neogene |journal=Episodes |volume=27 |issue=2 |pages=83–100 |id={{CORE output|11773078}} |doi=10.18814/epiiugs/2004/v27i2/002 |doi-access=free }} | ||
* {{cite news|url=https://www.npr.org/sections/13.7/2014/09/28/351692717/embracing-deep-time-thinking|last= Ialenti|first=Vincent|title=Embracing 'Deep Time' Thinking.|newspaper= NPR|date= 28 September 2014|publisher=NPR Cosmos & Culture}} | * {{cite news|url=https://www.npr.org/sections/13.7/2014/09/28/351692717/embracing-deep-time-thinking|last= Ialenti|first=Vincent|title=Embracing 'Deep Time' Thinking.|newspaper= NPR|date= 28 September 2014|publisher=NPR Cosmos & Culture}} | ||
* {{cite news|url=https://www.npr.org/sections/13.7/2014/09/21/350344129/pondering-deep-time-could-inspire-new-ways-to-view-climate-change |last=Ialenti|first=Vincent|title=Pondering 'Deep Time' Could Inspire New Ways To View Climate Change.|newspaper=NPR|date=21 September 2014|publisher=NPR Cosmos & Culture}} | * {{cite news|url=https://www.npr.org/sections/13.7/2014/09/21/350344129/pondering-deep-time-could-inspire-new-ways-to-view-climate-change |last=Ialenti|first=Vincent|title=Pondering 'Deep Time' Could Inspire New Ways To View Climate Change.|newspaper=NPR|date=21 September 2014|publisher=NPR Cosmos & Culture}} | ||
* {{cite journal | * {{cite journal |last1=Knoll |first1=Andrew H. |last2=Walter |first2=Malcolm R. |last3=Narbonne |first3=Guy M. |last4=Christie-Blick |first4=Nicholas |title=A New Period for the Geologic Time Scale |journal=Science |date=30 July 2004 |volume=305 |issue=5684 |pages=621–622 |doi=10.1126/science.1098803 |pmid=15286353 }} | ||
* {{cite book |date=2010 |last=Levin|first=Harold L. |chapter=Time and Geology |chapter-url= | * {{cite book |date=2010 |last=Levin|first=Harold L. |chapter=Time and Geology |chapter-url={{GBurl|D0yl7Cqsu78C|p=29}} |title=The Earth Through Time |place=Hoboken, New Jersey |publisher=John Wiley & Sons |isbn=978-0-470-38774-0 }} | ||
* {{cite book |last=Montenari |first=Michael | * {{cite book |editor1-last=Montenari |editor1-first=Michael |title=Stratigraphy & Timescales |date=2016 |publisher=Academic Press |isbn=978-0-12-811550-3 |url=https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/1/suppl/C }} | ||
* {{cite book |last=Montenari |first=Michael |url=https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/2/suppl/C |title=Advances in Sequence Stratigraphy |date=2017 |edition=1st |location=Amsterdam |publisher=Academic Press (Elsevier) |isbn=978-0-12-813077-3}} | * {{cite book |last=Montenari |first=Michael |url=https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/2/suppl/C |title=Advances in Sequence Stratigraphy |date=2017 |edition=1st |location=Amsterdam |publisher=Academic Press (Elsevier) |isbn=978-0-12-813077-3}} | ||
* {{cite book |last=Montenari |first=Michael |date=2018 |url=https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/3/suppl/C |title=Cyclostratigraphy and Astrochronology |edition=1st |location=Amsterdam |publisher=Academic Press (Elsevier) |isbn=978-0-12-815098-6}} | * {{cite book |editor1-last=Montenari |editor1-first=Michael |date=2018 |url=https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/3/suppl/C |title=Cyclostratigraphy and Astrochronology |edition=1st |location=Amsterdam |publisher=Academic Press (Elsevier) |isbn=978-0-12-815098-6}} | ||
* {{cite book |last=Montenari |first=Michael |date=2019 |url=https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/4/suppl/C |title=Case Studies in Isotope Stratigraphy |edition=1st |location=Amsterdam |publisher=Academic Press (Elsevier) |isbn=978-0-12-817552-1}} | * {{cite book |editor1-last=Montenari |editor1-first=Michael |date=2019 |url=https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/4/suppl/C |title=Case Studies in Isotope Stratigraphy |edition=1st |location=Amsterdam |publisher=Academic Press (Elsevier) |isbn=978-0-12-817552-1}} | ||
* {{cite book |last=Montenari |first=Michael |date=2020 |url=https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/5/suppl/C |title=Carbon Isotope Stratigraphy |edition=1st |location=Amsterdam |publisher=Academic Press (Elsevier) |isbn=978-0-12-820991-2}} | * {{cite book |editor1-last=Montenari |editor1-first=Michael |date=2020 |url=https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/5/suppl/C |title=Carbon Isotope Stratigraphy |edition=1st |location=Amsterdam |publisher=Academic Press (Elsevier) |isbn=978-0-12-820991-2}} | ||
*{{cite book |last=Montenari |first=Michael |date=2021 |url=https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/6/suppl/C |title=Calcareous Nannofossil Biostratigraphy |edition=1st |location=Amsterdam |publisher=Academic Press (Elsevier) |isbn=978-0-12-824624-5}} | *{{cite book |editor1-last=Montenari |editor1-first=Michael |date=2021 |url=https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/6/suppl/C |title=Calcareous Nannofossil Biostratigraphy |edition=1st |location=Amsterdam |publisher=Academic Press (Elsevier) |isbn=978-0-12-824624-5}} | ||
*Montenari | * {{cite book |editor1-last=Montenari |editor1-first=Michael |date=2022 |url=https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/7/suppl/C |title=Integrated Quaternary Stratigraphy |edition=1st |location=Amsterdam |publisher=Academic Press (Elsevier) |isbn=978-0-323-98913-8 }} | ||
*Montenari | * {{cite book |editor1-last=Montenari |editor1-first=Michael |date=2023 |url=https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/8/suppl/C |title=Stratigraphy of Geo- and Biodynamic Processes |edition=1st |location=Amsterdam |publisher=Academic Press (Elsevier) |isbn=978-0-323-99242-8 }} | ||
* Nichols | * {{cite book |last1=Nichols |first1=Gary |title=Sedimentology and Stratigraphy |date=2013 |publisher=John Wiley & Sons |isbn=978-1-118-68777-2 }} | ||
* Williams | * {{cite book |last1=Williams |first1=Aiden |title=Sedimentology and Stratigraphy |date=2019 |publisher=Callisto Reference |isbn=978-1-64116-075-9 }} | ||
==External links== | ==External links== | ||
| Line 1,400: | Line 1,005: | ||
* [https://www.seegrid.csiro.au/twiki/bin/view/CGIModel/GeologicTime SeeGrid: Geological Time Systems]. {{Webarchive|url=https://web.archive.org/web/20080723195950/https://www.seegrid.csiro.au/twiki/bin/view/CGIModel/GeologicTime |date=23 July 2008 }}. Information model for the geologic time scale. | * [https://www.seegrid.csiro.au/twiki/bin/view/CGIModel/GeologicTime SeeGrid: Geological Time Systems]. {{Webarchive|url=https://web.archive.org/web/20080723195950/https://www.seegrid.csiro.au/twiki/bin/view/CGIModel/GeologicTime |date=23 July 2008 }}. Information model for the geologic time scale. | ||
* [http://exploringtime.org/?page=segments Exploring Time] from Planck Time to the lifespan of the universe | * [http://exploringtime.org/?page=segments Exploring Time] from Planck Time to the lifespan of the universe | ||
* Lane, Alfred C, and Marble, John Putman 1937. [https://books.google.com/books?id=ckIrAAAAYAAJ Report of the Committee on the measurement of geologic time] | * Lane, Alfred C, and Marble, John Putman 1937. [https://books.google.com/books?id=ckIrAAAAYAAJ Report of the Committee on the measurement of geologic time] | ||
* [https://web.archive.org/web/20110714173934/http://www.newsciencelessons.com/geology_lesson_plans.html Lessons for Children on Geologic Time] (archived 14 July 2011) | * [https://web.archive.org/web/20110714173934/http://www.newsciencelessons.com/geology_lesson_plans.html Lessons for Children on Geologic Time] (archived 14 July 2011) | ||