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Geologic time scale
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<h2 id="principles">Principles</h2> <p class="note">See also: <a href="/facts/Age_of_Earth/MxNh2Q11">Age of Earth</a>, <a href="/facts/History_of_Earth/0aEAQF0k">History of Earth</a>, and <a href="/facts/Geological_history_of_Earth/Jx7ClmF4">Geological history of Earth</a></p> <p>The geologic time scale is a way of representing <a href="/facts/Deep_time/0Pxg29TF">deep time</a> based on events that have occurred through <a href="/facts/History_of_Earth/0aEAQF0k">Earth's history</a>, a time span of about <a href="/facts/Age_of_Earth/MxNh2Q11">4.54 ± 0.05 Ga</a> (4.54 billion years).<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> It chronologically organises strata, and subsequently time, by observing fundamental changes in stratigraphy that correspond to major geological or paleontological events. For example, the <a href="/facts/Cretaceous%25E2%2580%2593Paleogene_extinction_event/HNyDuEcx">Cretaceous–Paleogene extinction event</a>, marks the lower boundary of the <a href="/facts/Paleogene/CNsEpdA4">Paleogene</a> System/Period and thus the boundary between the <a href="/facts/Cretaceous/nwKtFtKx">Cretaceous</a> and Paleogene systems/periods. For divisions prior to the <a href="/facts/Cryogenian/5NxvCx4r">Cryogenian</a>, arbitrary numeric boundary definitions (<a href="/facts/Global_Standard_Stratigraphic_Age/x6r5T5Cc">Global Standard Stratigraphic Ages</a>, GSSAs) are used to divide geologic time. Proposals have been made to better reconcile these divisions with the rock record.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a><a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p><p>Historically, regional geologic time scales were used<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> 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 <a href="/facts/Horizon_(geology)/5cRjMC0Y">horizons</a> that can be used to define the lower boundaries of chronostratigraphic units. Defining chronostratigraphic units in such a manner allows for the use of global, standardised nomenclature. The International Chronostratigraphic Chart represents this ongoing effort. </p><p>Several key principles are used to determine the relative relationships of rocks and thus their chronostratigraphic position.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a><a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> </p><p>The <a href="/facts/Law_of_superposition/PTd1xHg9">law of superposition</a> 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.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a><a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a><a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a><a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> In practice, this means a younger rock will lie on top of an older rock unless there is evidence to suggest otherwise. </p><p>The <a href="/facts/Principle_of_original_horizontality/V1CVvseb">principle of original horizontality</a> that states layers of sediments will originally be deposited horizontally under the action of gravity.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a><a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a><a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> However, it is now known that not all sedimentary layers are deposited purely horizontally,<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a><a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a> but this principle is still a useful concept. </p><p>The <a href="/facts/Principle_of_lateral_continuity/FSWACM9c">principle of lateral continuity</a> 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.<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a> Layers do not extend indefinitely; their limits are controlled by the amount and type of sediment in a <a href="/facts/Sedimentary_basin/dVkfKMrB">sedimentary basin</a>, and the geometry of that basin. </p><p>The principle of <a href="/facts/Cross-cutting_relationships/ukDst7Sj">cross-cutting relationships</a> that states a rock that cuts across another rock must be younger than the rock it cuts across.<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a><a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a><a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a><a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a> </p><p>The <a href="/facts/Law_of_included_fragments/CoSU39oY">law of included fragments</a> 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.<a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a><a class="footnote-ref" id="fnref:25" href="#fn:25"><sup>25</sup></a> </p><p>The relationships of <a href="/facts/Unconformity/yed5Tqdw">unconformities</a> 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.<a class="footnote-ref" id="fnref:26" href="#fn:26"><sup>26</sup></a> Observing the type and relationships of unconformities in strata allows geologist to understand the relative timing of the strata. </p><p>The <a href="/facts/Principle_of_faunal_succession/Wx9843yb">principle of faunal succession</a> (where applicable) that states rock strata contain distinctive sets of fossils that succeed each other vertically in a specific and reliable order.<a class="footnote-ref" id="fnref:27" href="#fn:27"><sup>27</sup></a><a class="footnote-ref" id="fnref:28" href="#fn:28"><sup>28</sup></a> This allows for a correlation of strata even when the horizon between them is not continuous. </p> <h2 id="divisions-of-geologic-time">Divisions of geologic time</h2> <p class="note">See also: <a href="/facts/Stratigraphy/o3J6Ij3R">Stratigraphy</a>, <a href="/facts/Chronostratigraphy/L3XU1Uh3">Chronostratigraphy</a>, <a href="/facts/Biostratigraphy/AzdPX12G">Biostratigraphy</a>, <a href="/facts/Magnetostratigraphy/k3tAxhpq">Magnetostratigraphy</a>, <a href="/facts/Lithostratigraphy/KhskmKLs">Lithostratigraphy</a>, and <a href="/facts/Geochronology/U8hRTGwL">Geochronology</a></p> <p>The geologic time scale is divided into chronostratigraphic units and their corresponding geochronologic units. </p> <ul><li>An eon is the largest geochronologic time unit and is equivalent to a chronostratigraphic <a href="/facts/Eonothem/bQhsV7sg">eonothem</a>.<a class="footnote-ref" id="fnref:29" href="#fn:29"><sup>29</sup></a> There are four formally defined eons: the <a href="/facts/Hadean/j7LWS4ah">Hadean</a>, <a href="/facts/Archean/PHt8Sm8n">Archean</a>, <a href="/facts/Proterozoic/sSGXxqUU">Proterozoic</a> and <a href="/facts/Phanerozoic/EKKuYnwl">Phanerozoic</a>.<a class="footnote-ref" id="fnref:30" href="#fn:30"><sup>30</sup></a></li> <li>An era is the second largest geochronologic time unit and is equivalent to a chronostratigraphic <a href="/facts/Erathem/IGVtnJ3d">erathem</a>.<a class="footnote-ref" id="fnref:31" href="#fn:31"><sup>31</sup></a><a class="footnote-ref" id="fnref:32" href="#fn:32"><sup>32</sup></a> There are ten defined eras: the <a href="/facts/Eoarchean/q7KzQNHD">Eoarchean</a>, <a href="/facts/Paleoarchean/5cldXjwo">Paleoarchean</a>, <a href="/facts/Mesoarchean/jsK450vc">Mesoarchean</a>, <a href="/facts/Neoarchean/fCh6XLKA">Neoarchean</a>, <a href="/facts/Paleoproterozoic/gMS69p5r">Paleoproterozoic</a>, <a href="/facts/Mesoproterozoic/bJ8uWQUH">Mesoproterozoic</a>, <a href="/facts/Neoproterozoic/89NsnsM1">Neoproterozoic</a>, <a href="/facts/Paleozoic/5qe2wz7U">Paleozoic</a>, <a href="/facts/Mesozoic/yYsvXGPa">Mesozoic</a> and <a href="/facts/Cenozoic/yFslcz6n">Cenozoic</a>, with none from the Hadean eon.<a class="footnote-ref" id="fnref:33" href="#fn:33"><sup>33</sup></a></li> <li>A period is equivalent to a chronostratigraphic <a href="/facts/System_(stratigraphy)/eEt8kSgg">system</a>.<a class="footnote-ref" id="fnref:34" href="#fn:34"><sup>34</sup></a><a class="footnote-ref" id="fnref:35" href="#fn:35"><sup>35</sup></a> There are 22 defined periods, with the current being the <a href="/facts/Quaternary/3cEgHAqc">Quaternary</a> period.<a class="footnote-ref" id="fnref:36" href="#fn:36"><sup>36</sup></a> As an exception, two subperiods are used for the <a href="/facts/Carboniferous/BRKlkYyd">Carboniferous Period</a>.<a class="footnote-ref" id="fnref:37" href="#fn:37"><sup>37</sup></a></li> <li>An epoch is the second smallest geochronologic unit. It is equivalent to a chronostratigraphic <a href="/facts/Series_(stratigraphy)/KgmTDDy5">series</a>.<a class="footnote-ref" id="fnref:38" href="#fn:38"><sup>38</sup></a><a class="footnote-ref" id="fnref:39" href="#fn:39"><sup>39</sup></a> There are 37 defined epochs and one informal one. The current epoch is the <a href="/facts/Holocene/sppPgwW5">Holocene</a>. There are also 11 subepochs which are all within the <a href="/facts/Neogene/zUJxvjuH">Neogene</a> and Quaternary.<a class="footnote-ref" id="fnref:40" href="#fn:40"><sup>40</sup></a> The use of subepochs as formal units in international chronostratigraphy was ratified in 2022.<a class="footnote-ref" id="fnref:41" href="#fn:41"><sup>41</sup></a></li> <li>An age is the smallest hierarchical geochronologic unit. It is equivalent to a chronostratigraphic <a href="/facts/Stage_(stratigraphy)/6HActMK7">stage</a>.<a class="footnote-ref" id="fnref:42" href="#fn:42"><sup>42</sup></a><a class="footnote-ref" id="fnref:43" href="#fn:43"><sup>43</sup></a> There are 96 formal and five informal ages.<a class="footnote-ref" id="fnref:44" href="#fn:44"><sup>44</sup></a> The current age is the <a href="/facts/Meghalayan/QsRlppAh">Meghalayan</a>.</li> <li>A <i>chron</i> is a non-hierarchical formal geochronology unit of unspecified rank and is equivalent to a chronostratigraphic <a href="/facts/Chronozone/SCqGb2Bs">chronozone</a>.<a class="footnote-ref" id="fnref:45" href="#fn:45"><sup>45</sup></a> These correlate with <a href="/facts/Magnetostratigraphy/k3tAxhpq">magnetostratigraphic</a>, <a href="/facts/Lithostratigraphy/KhskmKLs">lithostratigraphic</a>, or <a href="/facts/Biostratigraphy/AzdPX12G">biostratigraphic</a> units as they are based on previously defined stratigraphic units or geologic features.</li></ul> Formal, hierarchical units of the geologic time scale (largest to smallest)<table><tbody><tr><th>Chronostratigraphic unit (strata)</th><th>Geochronologic unit (time)</th><th>Time span<a class="footnote-ref" id="fnref:46" href="#fn:46"><sup>46</sup></a></th></tr><tr><td>Eonothem</td><td>Eon</td><td>Several hundred million years to two billion years</td></tr><tr><td>Erathem</td><td>Era</td><td>Tens to hundreds of millions of years</td></tr><tr><td>System</td><td>Period</td><td>Millions of years to tens of millions of years</td></tr><tr><td>Series</td><td>Epoch</td><td>Hundreds of thousands of years to tens of millions of years</td></tr><tr><td>Subseries</td><td>Subepoch</td><td>Thousands of years to millions of years</td></tr><tr><td>Stage</td><td>Age</td><td>Thousands of years to millions of years</td></tr></tbody></table> <p>The subdivisions Early and Late are used as the geochronologic equivalents of the chronostratigraphic Lower and Upper, e.g., Early <a href="/facts/Triassic/r6CNxKXC">Triassic</a> Period (geochronologic unit) is used in place of Lower Triassic System (chronostratigraphic unit). </p><p>Rocks representing a given chronostratigraphic unit are that chronostratigraphic unit, and the time they were laid down in is the geochronologic unit, e.g., the rocks that represent the <a href="/facts/Silurian/1qx4epPg">Silurian</a> System are the Silurian System and they were deposited during the Silurian Period. This definition means the numeric age of a geochronologic unit can be changed (and is more often subject to change) when refined by geochronometry while the equivalent chronostratigraphic unit (the revision of which is less frequent) remains unchanged. For example, in early 2022, the boundary between the <a href="/facts/Ediacaran/z8jSUITT">Ediacaran</a> and <a href="/facts/Cambrian/jIfzKtod">Cambrian</a> <a href="/facts/Period_(geologic_time)/6LBR11yQ">periods</a> (geochronologic units) was revised from 541 Ma to 538.8 Ma but the rock definition of the boundary (GSSP) at the base of the Cambrian, and thus the boundary between the Ediacaran and Cambrian <a href="/facts/System_(stratigraphy)/eEt8kSgg">systems</a> (chronostratigraphic units) has not been changed; rather, the absolute age has merely been refined. </p> <h3>Terminology</h3> <p><a href="/facts/Chronostratigraphy/L3XU1Uh3">Chronostratigraphy</a> is the element of <a href="/facts/Stratigraphy/o3J6Ij3R">stratigraphy</a> that deals with the relation between rock bodies and the relative measurement of geological time.<a class="footnote-ref" id="fnref:47" href="#fn:47"><sup>47</sup></a> It is the process where distinct strata between defined stratigraphic horizons are assigned to represent a relative interval of geologic time. </p><p>A chronostratigraphic unit is a body of rock, layered or unlayered, that is defined between specified stratigraphic horizons which represent specified intervals of geologic time. They include all rocks representative of a specific interval of geologic time, and only this time span. Eonothem, erathem, system, series, subseries, stage, and substage are the hierarchical chronostratigraphic units.<a class="footnote-ref" id="fnref:48" href="#fn:48"><sup>48</sup></a> </p><p>A geochronologic unit is a subdivision of geologic time. It is a numeric representation of an intangible property (time).<a class="footnote-ref" id="fnref:49" href="#fn:49"><sup>49</sup></a> These units are arranged in a hierarchy: eon, era, period, epoch, subepoch, age, and subage.<a class="footnote-ref" id="fnref:50" href="#fn:50"><sup>50</sup></a> Geochronology is the scientific branch of geology that aims to determine the age of rocks, fossils, and sediments either through absolute (e.g., <a href="/facts/Radiometric_dating/bDFjdPqV">radiometric dating</a>) or relative means (e.g., <a href="/facts/Law_of_superposition/PTd1xHg9">stratigraphic position</a>, <a href="/facts/Paleomagnetism/kDwUXDX5">paleomagnetism</a>, <a href="/facts/Stable_isotope_ratio/vgcdxgjA">stable isotope ratios</a>). <a href="/facts/Geochronometry/Dd34PsWk">Geochronometry</a> is the field of geochronology that numerically quantifies geologic time.<a class="footnote-ref" id="fnref:51" href="#fn:51"><sup>51</sup></a> </p><p>A <a href="/facts/Global_Boundary_Stratotype_Section_and_Point/B6NDa75W">Global Boundary Stratotype Section and Point</a> (GSSP) is an internationally agreed-upon reference point on a <a href="/facts/Stratigraphic_section/BBxnkItj">stratigraphic section</a> that defines the lower boundaries of stages on the geologic time scale.<a class="footnote-ref" id="fnref:52" href="#fn:52"><sup>52</sup></a> (Recently this has been used to define the base of a system)<a class="footnote-ref" id="fnref:53" href="#fn:53"><sup>53</sup></a> </p><p>A <a href="/facts/Global_Standard_Stratigraphic_Age/x6r5T5Cc">Global Standard Stratigraphic Age</a> (GSSA)<a class="footnote-ref" id="fnref:54" href="#fn:54"><sup>54</sup></a> is a numeric-only, chronologic reference point used to define the base of geochronologic units prior to the Cryogenian. These points are arbitrarily defined.<a class="footnote-ref" id="fnref:55" href="#fn:55"><sup>55</sup></a> They are used where GSSPs have not yet been established. Research is ongoing to define GSSPs for the base of all units that are currently defined by GSSAs. </p><p>The standard international units of the geologic time scale are published by the International Commission on Stratigraphy on the International Chronostratigraphic Chart; however, regional terms are still in use in some areas. The numeric values on the International Chronostratigrahpic Chart are represented by the unit <a href="/facts/Megaannum/51V242hh">Ma</a> (megaannum, for 'million <a href="/facts/Year/51V242hh">years</a>'). For example, 201.4 ± 0.2 Ma, the lower boundary of the <a href="/facts/Jurassic/o5Cy4KzX">Jurassic</a> Period, is defined as 201,400,000 years old with an uncertainty of 200,000 years. Other <a href="/facts/Si_prefix/Y2MzkaeL">SI prefix</a> units commonly used by geologists are <a href="/facts/Gigaannum/51V242hh">Ga</a> (gigaannum, billion years), and <a href="/facts/Kiloannums/51V242hh">ka</a> (kiloannum, thousand years), with the latter often represented in calibrated units (<a href="/facts/Before_Present/BywUcMvW">before present</a>). </p> <h2 id="naming-of-geologic-time">Naming of geologic time</h2> <p>The names of geologic time units are defined for chronostratigraphic units with the corresponding geochronologic unit sharing the same name with a change to the suffix (e.g. Phanerozoic <a href="/facts/Eonothem/bQhsV7sg">Eonothem</a> becomes the Phanerozoic Eon). Names of erathems in the Phanerozoic were chosen to reflect major changes in the history of life on Earth: <a href="/facts/Paleozoic/5qe2wz7U">Paleozoic</a> (old life), <a href="/facts/Mesozoic/yYsvXGPa">Mesozoic</a> (middle life), and <a href="/facts/Cenozoic/yFslcz6n">Cenozoic</a> (new life). Names of systems are diverse in origin, with some indicating chronologic position (e.g., Paleogene), while others are named for <a href="/facts/Lithology/WLIJXzGj">lithology</a> (e.g., Cretaceous), <a href="/facts/Geography/TRd1Toyo">geography</a> (e.g., <a href="/facts/Permian/CYgLgu5u">Permian</a>), or are tribal (e.g., <a href="/facts/Ordovician/BjMrLIEA">Ordovician</a>) in origin. Most currently recognised series and subseries are named for their position within a system/series (early/middle/late); however, the International Commission on Stratigraphy advocates for all new series and subseries to be named for a geographic feature in the vicinity of its <a href="/facts/Stratotype/GD9DvxGF">stratotype</a> or <a href="/facts/Type_locality_(geology)/ky6QjASt">type locality</a>. The name of stages should also be derived from a geographic feature in the locality of its stratotype or type locality.<a class="footnote-ref" id="fnref:56" href="#fn:56"><sup>56</sup></a> </p><p>Informally, the time before the Cambrian is often referred to as the <a href="/facts/Precambrian/zjF3N3Rx">Precambrian</a> or pre-Cambrian (Supereon).<a class="footnote-ref" id="fnref:57" href="#fn:57"><sup>57</sup></a><a class="footnote-ref" id="fnref:58" href="#fn:58"><sup>58</sup></a> </p> Time span and <a href="/facts/Etymology/18QG6y67">etymology</a> of geologic eonothem/eon names<table><tbody><tr><th>Name</th><th>Time span</th><th>Duration (million years)</th><th>Etymology of name</th></tr><tr><td><a href="/facts/Phanerozoic/EKKuYnwl">Phanerozoic</a></td><td><a href="https://geoltime.github.io/?Ma=538.8–0">538.8 to 0</a> million years ago</td><td>538.8</td><td>From Greek φανερός (<i>phanerós</i>) 'visible' or 'abundant' and ζωή (<i>zoē</i>) 'life'.</td></tr><tr><td><a href="/facts/Proterozoic/sSGXxqUU">Proterozoic</a></td><td><a href="https://geoltime.github.io/?Ma=2500–538.8">2,500 to 538.8</a> million years ago</td><td>1961.2</td><td>From Greek πρότερος (<i>próteros</i>) 'former' or 'earlier' and ζωή (<i>zoē</i>) 'life'.</td></tr><tr><td><a href="/facts/Archean/PHt8Sm8n">Archean</a></td><td><a href="https://geoltime.github.io/?Ma=4031–2500">4,031 to 2,500</a> million years ago</td><td>1531</td><td>From Greek <a href="/facts/%25E1%25BC%2588%25CF%2581%25CF%2587%25CE%25AE/qneq1n7m">ἀρχή</a> (<i>archē</i>) 'beginning, origin'.</td></tr><tr><td><a href="/facts/Hadean/j7LWS4ah">Hadean</a></td><td><a href="https://geoltime.github.io/?Ma=4567–4031">4,567 to 4,031</a> million years ago</td><td>536</td><td>From <a href="/facts/Hades/L8jg3utR">Hades</a>, <a href="/facts/Ancient_Greek_language/LIK7NlUh">Ancient Greek</a>: ᾍδης, <a href="/facts/Romanization_of_Ancient_Greek/KTELT9Aq">romanized</a>: <i>Háidēs</i>, the god of the underworld (hell, the inferno) in Greek mythology.</td></tr></tbody></table> Time span and etymology of geologic erathem/era names<table><tbody><tr><th>Name</th><th>Time span</th><th>Duration (million years)</th><th>Etymology of name</th></tr><tr><td><a href="/facts/Cenozoic/yFslcz6n">Cenozoic</a></td><td><a href="https://geoltime.github.io/?Ma=66–0">66 to 0</a> million years ago</td><td>66</td><td>From Greek καινός (<i>kainós</i>) 'new' and ζωή (<i>zōḗ</i>) 'life'.</td></tr><tr><td><a href="/facts/Mesozoic/yYsvXGPa">Mesozoic</a></td><td><a href="https://geoltime.github.io/?Ma=251.9–66">251.9 to 66</a> million years ago</td><td>185.902</td><td>From Greek μέσο (<i>méso</i>) 'middle' and ζωή (<i>zōḗ</i>) 'life'.</td></tr><tr><td><a href="/facts/Paleozoic/5qe2wz7U">Paleozoic</a></td><td><a href="https://geoltime.github.io/?Ma=538.8–251.9">538.8 to 251.9</a> million years ago</td><td>286.898</td><td>From Greek παλιός (<i>palaiós</i>) 'old' and ζωή (<i>zōḗ</i>) 'life'.</td></tr><tr><td><a href="/facts/Neoproterozoic/89NsnsM1">Neoproterozoic</a></td><td><a href="https://geoltime.github.io/?Ma=1000–538.8">1,000 to 538.8</a> million years ago</td><td>461.2</td><td>From Greek νέος (<i>néos</i>) 'new' or 'young', πρότερος (<i>próteros</i>) 'former' or 'earlier', and ζωή (<i>zōḗ</i>) 'life'.</td></tr><tr><td><a href="/facts/Mesoproterozoic/bJ8uWQUH">Mesoproterozoic</a></td><td><a href="https://geoltime.github.io/?Ma=1600–1000">1,600 to 1,000</a> million years ago</td><td>600</td><td>From Greek μέσο (<i>méso</i>) 'middle', πρότερος (<i>próteros</i>) 'former' or 'earlier', and ζωή (<i>zōḗ</i>) 'life'.</td></tr><tr><td><a href="/facts/Paleoproterozoic/gMS69p5r">Paleoproterozoic</a></td><td><a href="https://geoltime.github.io/?Ma=2500–1600">2,500 to 1,600</a> million years ago</td><td>900</td><td>From Greek παλιός (<i>palaiós</i>) 'old', πρότερος (<i>próteros</i>) 'former' or 'earlier', and ζωή (<i>zōḗ</i>) 'life'.</td></tr><tr><td><a href="/facts/Neoarchean/fCh6XLKA">Neoarchean</a></td><td><a href="https://geoltime.github.io/?Ma=2800–2500">2,800 to 2,500</a> million years ago</td><td>300</td><td>From Greek νέος (<i>néos</i>) 'new' or 'young' and ἀρχαῖος (<i>arkhaîos</i>) 'ancient'.</td></tr><tr><td><a href="/facts/Mesoarchean/jsK450vc">Mesoarchean</a></td><td><a href="https://geoltime.github.io/?Ma=3200–2800">3,200 to 2,800</a> million years ago</td><td>400</td><td>From Greek μέσο (<i>méso</i>) 'middle' and ἀρχαῖος (<i>arkhaîos</i>) 'ancient'.</td></tr><tr><td><a href="/facts/Paleoarchean/5cldXjwo">Paleoarchean</a></td><td><a href="https://geoltime.github.io/?Ma=3600–3200">3,600 to 3,200</a> million years ago</td><td>400</td><td>From Greek παλιός (<i>palaiós</i>) 'old' and ἀρχαῖος (<i>arkhaîos</i>) 'ancient'.</td></tr><tr><td><a href="/facts/Eoarchean/q7KzQNHD">Eoarchean</a></td><td><a href="https://geoltime.github.io/?Ma=4031–3600">4,031 to 3,600</a> million years ago</td><td>431</td><td>From Greek ἠώς (<i>ēōs</i>) 'dawn' and ἀρχαῖος (<i>arkhaîos</i>) 'ancient'.</td></tr></tbody></table> Time span and etymology of geologic system/period names<table><tbody><tr><th>Name</th><th>Time span</th><th>Duration (million years)</th><th>Etymology of name</th></tr><tr><td><a href="/facts/Quaternary/3cEgHAqc">Quaternary</a></td><td><a href="https://geoltime.github.io/?Ma=2.6–0">2.6 to 0</a> million years ago</td><td>2.58</td><td>First introduced by <a href="/facts/Jules_Desnoyers/nCEhpC66">Jules Desnoyers</a> in 1829 for sediments in <a href="/facts/France/CxIeIKM3">France</a>'s <a href="/facts/Seine/Chd1gSKo">Seine</a> Basin that appeared to be younger than <a href="/facts/Tertiary/Krcz3olj">Tertiary</a><a class="footnote-ref" id="fnref:59" href="#fn:59"><sup>59</sup></a> rocks.<a class="footnote-ref" id="fnref:60" href="#fn:60"><sup>60</sup></a></td></tr><tr><td><a href="/facts/Neogene/zUJxvjuH">Neogene</a></td><td><a href="https://geoltime.github.io/?Ma=23–2.6">23 to 2.6</a> million years ago</td><td>20.46</td><td>Derived from Greek νέος (<i>néos</i>) 'new' and γενεά (<i>geneá</i>) 'genesis' or 'birth'.</td></tr><tr><td><a href="/facts/Paleogene/CNsEpdA4">Paleogene</a></td><td><a href="https://geoltime.github.io/?Ma=66–23">66 to 23</a> million years ago</td><td>42.96</td><td>Derived from Greek παλιός (<i>palaiós</i>) 'old' and γενεά (<i>geneá</i>) 'genesis' or 'birth'.</td></tr><tr><td><a href="/facts/Cretaceous/nwKtFtKx">Cretaceous</a></td><td><a href="/facts/Tilde/wQTx6ytR">~</a><a href="https://geoltime.github.io/?Ma=143.1–66">143.1 to 66</a> million years ago</td><td>~77.1</td><td>Derived from <i>Terrain Crétacé</i> used in 1822 by <a href="/facts/Jean_d%2527Omalius_d%2527Halloy/L8RhCCtp">Jean d'Omalius d'Halloy</a> in reference to extensive beds of <a href="/facts/Chalk/b6hepsNS">chalk</a> within the <a href="/facts/Paris_Basin/G92w0pS0">Paris Basin</a>.<a class="footnote-ref" id="fnref:61" href="#fn:61"><sup>61</sup></a> Ultimately derived from <a href="/facts/Latin/pM3Kge85">Latin</a> <i>crēta</i> 'chalk'.</td></tr><tr><td><a href="/facts/Jurassic/o5Cy4KzX">Jurassic</a></td><td><a href="https://geoltime.github.io/?Ma=201.4–143.1">201.4 to 143.1</a> million years ago</td><td>~58.3</td><td>Named after the <a href="/facts/Jura_Mountains/8x0AMMft">Jura Mountains</a>. Originally used by <a href="/facts/Alexander_von_Humboldt/5AuxyDbh">Alexander von Humboldt</a> as 'Jura Kalkstein' (Jura limestone) in 1799.<a class="footnote-ref" id="fnref:62" href="#fn:62"><sup>62</sup></a> <a href="/facts/Alexandre_Brongniart/tDYWo0ob">Alexandre Brongniart</a> was the first to publish the term Jurassic in 1829.<a class="footnote-ref" id="fnref:63" href="#fn:63"><sup>63</sup></a><a class="footnote-ref" id="fnref:64" href="#fn:64"><sup>64</sup></a></td></tr><tr><td><a href="/facts/Triassic/r6CNxKXC">Triassic</a></td><td><a href="https://geoltime.github.io/?Ma=251.9–201.4">251.9 to 201.4</a> million years ago</td><td>50.502</td><td>From the <i>Trias</i> of <a href="/facts/Friedrich_August_von_Alberti/uKwr64rx">Friedrich August von Alberti</a> in reference to a trio of formations widespread in southern <a href="/facts/Germany/paluuWBX">Germany</a>.</td></tr><tr><td><a href="/facts/Permian/CYgLgu5u">Permian</a></td><td><a href="https://geoltime.github.io/?Ma=298.9–251.9">298.9 to 251.9</a> million years ago</td><td>46.998</td><td>Named after the historical region of <a href="/facts/Perm_Governorate/K72SpumF">Perm</a>, <a href="/facts/Russian_Empire/hg1g5SpV">Russian Empire</a>.<a class="footnote-ref" id="fnref:65" href="#fn:65"><sup>65</sup></a></td></tr><tr><td><a href="/facts/Carboniferous/BRKlkYyd">Carboniferous</a></td><td><a href="https://geoltime.github.io/?Ma=358.9–298.9">358.9 to 298.9</a> million years ago</td><td>59.96</td><td>Means 'coal-bearing', from the <a href="/facts/Latin/pM3Kge85">Latin</a> carbō (<i>coal</i>) and ferō (<i>to bear, carry</i>).<a class="footnote-ref" id="fnref:66" href="#fn:66"><sup>66</sup></a></td></tr><tr><td><a href="/facts/Devonian/nWgakqzk">Devonian</a></td><td><a href="https://geoltime.github.io/?Ma=419.6–358.9">419.6 to 358.9</a> million years ago</td><td>60.76</td><td>Named after <a href="/facts/Devon/go3z9lDW">Devon</a>, England.<a class="footnote-ref" id="fnref:67" href="#fn:67"><sup>67</sup></a></td></tr><tr><td><a href="/facts/Silurian/1qx4epPg">Silurian</a></td><td><a href="https://geoltime.github.io/?Ma=443.1–419.6">443.1 to 419.6</a> million years ago</td><td>23.48</td><td>Named after the <a href="/facts/Celts/eMCVYAFz">Celtic</a> tribe, the <a href="/facts/Silures/UThkIPWh">Silures</a>.<a class="footnote-ref" id="fnref:68" href="#fn:68"><sup>68</sup></a></td></tr><tr><td><a href="/facts/Ordovician/BjMrLIEA">Ordovician</a></td><td><a href="https://geoltime.github.io/?Ma=486.9–443.1">486.9 to 443.1</a> million years ago</td><td>43.75</td><td>Named after the Celtic tribe, <a href="/facts/Ordovices/uEHIdrbI">Ordovices</a>.<a class="footnote-ref" id="fnref:69" href="#fn:69"><sup>69</sup></a><a class="footnote-ref" id="fnref:70" href="#fn:70"><sup>70</sup></a></td></tr><tr><td><a href="/facts/Cambrian/jIfzKtod">Cambrian</a></td><td><a href="https://geoltime.github.io/?Ma=538.8–486.9">538.8 to 486.9</a> million years ago</td><td>51.95</td><td>Named for <a href="/facts/Cambria/98EhyLNY">Cambria</a>, a <a href="/facts/Latin/pM3Kge85">latinised</a> form of the Welsh name for <a href="/facts/Wales/xa3W6PHH">Wales</a>, <i>Cymru</i>.<a class="footnote-ref" id="fnref:71" href="#fn:71"><sup>71</sup></a></td></tr><tr><td><a href="/facts/Ediacaran/z8jSUITT">Ediacaran</a></td><td><a href="https://geoltime.github.io/?Ma=635–538.8">635 to 538.8</a> million years ago</td><td>~96.2</td><td>Named for the <a href="/facts/Ediacara_Hills/PUTYs95Y">Ediacara Hills</a>. Ediacara is possibly a corruption of <a href="/facts/Kuyani/LmCbWyAv">Kuyani</a> 'Yata Takarra' 'hard or stony ground'.<a class="footnote-ref" id="fnref:72" href="#fn:72"><sup>72</sup></a><a class="footnote-ref" id="fnref:73" href="#fn:73"><sup>73</sup></a></td></tr><tr><td><a href="/facts/Cryogenian/5NxvCx4r">Cryogenian</a></td><td><a href="https://geoltime.github.io/?Ma=720–635">720 to 635</a> million years ago</td><td>~85</td><td>From Greek κρύος (<i>krýos</i>) 'cold' and γένεσις (<i>génesis</i>) 'birth'.<a class="footnote-ref" id="fnref:74" href="#fn:74"><sup>74</sup></a></td></tr><tr><td><a href="/facts/Tonian/qkGE6hCf">Tonian</a></td><td><a href="https://geoltime.github.io/?Ma=1000–720">1,000 to 720</a> million years ago</td><td>~280</td><td>From Greek τόνος (<i>tónos</i>) 'stretch'.<a class="footnote-ref" id="fnref:75" href="#fn:75"><sup>75</sup></a></td></tr><tr><td><a href="/facts/Stenian/JJ5tA2K1">Stenian</a></td><td><a href="https://geoltime.github.io/?Ma=1200–1000">1,200 to 1,000</a> million years ago</td><td>200</td><td>From Greek στενός (<i>stenós</i>) 'narrow'.<a class="footnote-ref" id="fnref:76" href="#fn:76"><sup>76</sup></a></td></tr><tr><td><a href="/facts/Ectasian/59eN5AKF">Ectasian</a></td><td><a href="https://geoltime.github.io/?Ma=1400–1200">1,400 to 1,200</a> million years ago</td><td>200</td><td>From Greek ἔκτᾰσῐς (<i>éktasis</i>) 'extension'.<a class="footnote-ref" id="fnref:77" href="#fn:77"><sup>77</sup></a></td></tr><tr><td><a href="/facts/Calymmian/kEjss5Ve">Calymmian</a></td><td><a href="https://geoltime.github.io/?Ma=1600–1400">1,600 to 1,400</a> million years ago</td><td>200</td><td>From Greek κάλυμμᾰ (<i>kálumma</i>) 'cover'.<a class="footnote-ref" id="fnref:78" href="#fn:78"><sup>78</sup></a></td></tr><tr><td><a href="/facts/Statherian/LHcg66kG">Statherian</a></td><td><a href="https://geoltime.github.io/?Ma=1800–1600">1,800 to 1,600</a> million years ago</td><td>200</td><td>From Greek σταθερός (<i>statherós</i>) 'stable'.<a class="footnote-ref" id="fnref:79" href="#fn:79"><sup>79</sup></a></td></tr><tr><td><a href="/facts/Orosirian/dajazQeI">Orosirian</a></td><td><a href="https://geoltime.github.io/?Ma=2050–1800">2,050 to 1,800</a> million years ago</td><td>250</td><td>From Greek ὀροσειρά (<i>oroseirá</i>) 'mountain range'.<a class="footnote-ref" id="fnref:80" href="#fn:80"><sup>80</sup></a></td></tr><tr><td><a href="/facts/Rhyacian/3IYRSHxd">Rhyacian</a></td><td><a href="https://geoltime.github.io/?Ma=2300–2050">2,300 to 2,050</a> million years ago</td><td>250</td><td>From Greek ῥύαξ (<i>rhýax</i>) 'stream of lava'.<a class="footnote-ref" id="fnref:81" href="#fn:81"><sup>81</sup></a></td></tr><tr><td><a href="/facts/Siderian/7aspCrFn">Siderian</a></td><td><a href="https://geoltime.github.io/?Ma=2500–2300">2,500 to 2,300</a> million years ago</td><td>200</td><td>From Greek σίδηρος (<i>sídēros</i>) '<a href="/facts/Iron/QK1JYy8E">iron</a>'.<a class="footnote-ref" id="fnref:82" href="#fn:82"><sup>82</sup></a></td></tr></tbody></table> Time span and etymology of geologic series/epoch names<table><tbody><tr><th>Name</th><th>Time span</th><th>Duration (million years)</th><th>Etymology of name</th></tr><tr><td><a href="/facts/Holocene/sppPgwW5">Holocene</a></td><td><a href="https://geoltime.github.io/?Ma=0.012–0">0.012 to 0</a> million years ago</td><td>0.0117</td><td>From Greek ὅλος (<i>hólos</i>) 'whole' and καινός (<i>kainós</i>) 'new'</td></tr><tr><td><a href="/facts/Pleistocene/0ya9eUp5">Pleistocene</a></td><td><a href="https://geoltime.github.io/?Ma=2.58–0.012">2.58 to 0.012</a> million years ago</td><td>2.5683</td><td>Coined in the early 1830s from Greek πλεῖστος (<i>pleîstos</i>) 'most' and καινός (<i>kainós</i>) 'new'</td></tr><tr><td><a href="/facts/Pliocene/MjcIVQ86">Pliocene</a></td><td><a href="https://geoltime.github.io/?Ma=5.33–2.58">5.33 to 2.58</a> million years ago</td><td>2.753</td><td>Coined in the early 1830s from Greek πλείων (<i>pleíōn</i>) 'more' and καινός (<i>kainós</i>) 'new'</td></tr><tr><td><a href="/facts/Miocene/cBRRzq4g">Miocene</a></td><td><a href="https://geoltime.github.io/?Ma=23.04–5.33">23.04 to 5.33</a> million years ago</td><td>17.707</td><td>Coined in the early 1830s from Greek μείων (<i>meíōn</i>) 'less' and καινός (<i>kainós</i>) 'new'</td></tr><tr><td><a href="/facts/Oligocene/n3gnNogo">Oligocene</a></td><td><a href="https://geoltime.github.io/?Ma=33.9–23.04">33.9 to 23.04</a> million years ago</td><td>10.86</td><td>Coined in the 1850s from Greek ὀλίγος (<i>olígos</i>) 'few' and καινός (<i>kainós</i>) 'new'</td></tr><tr><td><a href="/facts/Eocene/EYgI8Uco">Eocene</a></td><td><a href="https://geoltime.github.io/?Ma=56–33.9">56 to 33.9</a> million years ago</td><td>22.1</td><td>Coined in the early 1830s from Greek ἠώς (<i>ēōs</i>) 'dawn' and καινός (<i>kainós</i>) 'new', referring to the dawn of modern life during this epoch</td></tr><tr><td><a href="/facts/Paleocene/IWWoh8D9">Paleocene</a></td><td><a href="https://geoltime.github.io/?Ma=66–56">66 to 56</a> million years ago</td><td>10</td><td>Coined by <a href="/facts/Wilhelm_Philippe_Schimper/NfqyguHU">Wilhelm Philippe Schimper</a> in 1874 as a portmanteau of paleo- + Eocene, but on the surface from Greek παλαιός (<i>palaios</i>) 'old' and καινός (<i>kainós</i>) 'new'</td></tr><tr><td><a href="/facts/Upper_Cretaceous/pcHa4fBg">Upper Cretaceous</a></td><td><a href="https://geoltime.github.io/?Ma=100.5–66">100.5 to 66</a> million years ago</td><td>34.5</td><td rowspan="2">See <a href="/facts/Cretaceous/nwKtFtKx">Cretaceous</a></td></tr><tr><td><a href="/facts/Lower_Cretaceous/5uWEJGYC">Lower Cretaceous</a></td><td><a href="https://geoltime.github.io/?Ma=143.1–100.5">143.1 to 100.5</a> million years ago</td><td>42.6</td></tr><tr><td><a href="/facts/Upper_Jurassic/NzU9rlnL">Upper Jurassic</a></td><td><a href="https://geoltime.github.io/?Ma=161.5–143.1">161.5 to 143.1</a> million years ago</td><td>18.4</td><td rowspan="3">See <a href="/facts/Jurassic/o5Cy4KzX">Jurassic</a></td></tr><tr><td><a href="/facts/Middle_Jurassic/3XQSmQgU">Middle Jurassic</a></td><td><a href="https://geoltime.github.io/?Ma=174.7–161.5">174.7 to 161.5</a> million years ago</td><td>13.2</td></tr><tr><td><a href="/facts/Lower_Jurassic/atwEBpDz">Lower Jurassic</a></td><td><a href="https://geoltime.github.io/?Ma=201.4–174.7">201.4 to 174.7</a> million years ago</td><td>26.7</td></tr><tr><td><a href="/facts/Upper_Triassic/TazKYWQN">Upper Triassic</a></td><td><a href="https://geoltime.github.io/?Ma=237–201.4">237 to 201.4</a> million years ago</td><td>35.6</td><td rowspan="3">See <a href="/facts/Triassic/r6CNxKXC">Triassic</a></td></tr><tr><td><a href="/facts/Middle_Triassic/Y0FBoqA8">Middle Triassic</a></td><td><a href="https://geoltime.github.io/?Ma=246.7–237">246.7 to 237</a> million years ago</td><td>9.7</td></tr><tr><td><a href="/facts/Lower_Triassic/oBgudq2V">Lower Triassic</a></td><td><a href="https://geoltime.github.io/?Ma=251.9–246.7">251.9 to 246.7</a> million years ago</td><td>5.202</td></tr><tr><td><a href="/facts/Lopingian/l8Pdcf6k">Lopingian</a></td><td><a href="https://geoltime.github.io/?Ma=259.51–251.9">259.51 to 251.9</a> million years ago</td><td>7.608</td><td>Named for <a href="/facts/Leping/C8eFufKw">Loping</a>, China, an anglicization of Mandarin 乐平 (<i>lèpíng</i>) 'peaceful music'</td></tr><tr><td><a href="/facts/Guadalupian/rsksJLtV">Guadalupian</a></td><td><a href="https://geoltime.github.io/?Ma=274.4–259.51">274.4 to 259.51</a> million years ago</td><td>14.89</td><td>Named for the <a href="/facts/Guadalupe_Mountains/5Uwvl0RV">Guadalupe Mountains</a> of the American Southwest, ultimately from Arabic وَادِي ٱل (<i>wādī al</i>) 'valley of the' and Latin <i>lupus</i> 'wolf' via Spanish</td></tr><tr><td><a href="/facts/Cisuralian/DvIWAITS">Cisuralian</a></td><td><a href="https://geoltime.github.io/?Ma=298.9–274.4">298.9 to 274.4</a> million years ago</td><td>24.5</td><td>From Latin <i>cis-</i> (before) + Russian Урал (<i>Ural</i>), referring to the western slopes of the <a href="/facts/Ural_Mountains/gzNoPkt6">Ural Mountains</a></td></tr><tr><td><a href="/facts/Pennsylvanian_(geology)/Fc1LAJSX">Upper Pennsylvanian</a></td><td><a href="https://geoltime.github.io/?Ma=307–298.9">307 to 298.9</a> million years ago</td><td>8.1</td><td rowspan="3">Named for the US state of <a href="/facts/Pennsylvania/HGqC5bBm">Pennsylvania</a>, from <a href="/facts/William_Penn/LMWEtMpa">William Penn</a> + Latin <i>silvanus</i> (forest) + -ia by analogy to Transylvania</td></tr><tr><td><a href="/facts/Pennsylvanian_(geology)/Fc1LAJSX">Middle Pennsylvanian</a></td><td><a href="https://geoltime.github.io/?Ma=315.2–307">315.2 to 307</a> million years ago</td><td>8.2</td></tr><tr><td><a href="/facts/Pennsylvanian_(geology)/Fc1LAJSX">Lower Pennsylvanian</a></td><td><a href="https://geoltime.github.io/?Ma=323.4–315.2">323.4 to 315.2</a> million years ago</td><td>8.2</td></tr><tr><td><a href="/facts/Mississippian_(geology)/tqsS6Ifj">Upper Mississippian</a></td><td><a href="https://geoltime.github.io/?Ma=330.3–323.4">330.3 to 323.4</a> million years ago</td><td>6.9</td><td rowspan="3">Named for the <a href="/facts/Mississippi_River/RduarPzj">Mississippi River</a>, from Ojibwe ᒥᐦᓯᓰᐱ (<i>misi-ziibi</i>) 'great river'</td></tr><tr><td><a href="/facts/Mississippian_(geology)/tqsS6Ifj">Middle Mississippian</a></td><td><a href="https://geoltime.github.io/?Ma=346.7–330.3">346.7 to 330.3</a> million years ago</td><td>16.4</td></tr><tr><td><a href="/facts/Mississippian_(geology)/tqsS6Ifj">Lower Mississippian</a></td><td><a href="https://geoltime.github.io/?Ma=358.86–346.7">358.86 to 346.7</a> million years ago</td><td>12.16</td></tr><tr><td><a href="/facts/Upper_Devonian/nWgakqzk">Upper Devonian</a></td><td><a href="https://geoltime.github.io/?Ma=382.31–358.86">382.31 to 358.86</a> million years ago</td><td>23.45</td><td rowspan="3">See <a href="/facts/Devonian/nWgakqzk">Devonian</a></td></tr><tr><td><a href="/facts/Middle_Devonian/nWgakqzk">Middle Devonian</a></td><td><a href="https://geoltime.github.io/?Ma=393.47–382.31">393.47 to 382.31</a> million years ago</td><td>11.16</td></tr><tr><td><a href="/facts/Lower_Devonian/nWgakqzk">Lower Devonian</a></td><td><a href="https://geoltime.github.io/?Ma=419.62–393.47">419.62 to 393.47</a> million years ago</td><td>26.15</td></tr><tr><td><a href="/facts/Pridoli_Epoch/pF1CyLKB">Pridoli</a></td><td><a href="https://geoltime.github.io/?Ma=422.7–419.62">422.7 to 419.62</a> million years ago</td><td>3.08</td><td>Named for the Homolka a Přídolí nature reserve near <a href="/facts/Prague/txpRNTUE">Prague</a>, Czechia</td></tr><tr><td><a href="/facts/Ludlow_Epoch/GPDcYWc8">Ludlow</a></td><td><a href="https://geoltime.github.io/?Ma=426.7–422.7">426.7 to 422.7</a> million years ago</td><td>4</td><td>Named after <a href="/facts/Ludlow/MuK8UdqJ">Ludlow</a>, England</td></tr><tr><td><a href="/facts/Wenlock_Epoch/p8uSWFBt">Wenlock</a></td><td><a href="https://geoltime.github.io/?Ma=432.9–426.7">432.9 to 426.7</a> million years ago</td><td>6.2</td><td>Named for the <a href="/facts/Wenlock_Edge/YmqeBQHm">Wenlock Edge</a> in <a href="/facts/Shropshire/6JcmluAA">Shropshire</a>, England</td></tr><tr><td><a href="/facts/Llandovery_Epoch/ITDPljb3">Llandovery</a></td><td><a href="https://geoltime.github.io/?Ma=443.1–432.9">443.1 to 432.9</a> million years ago</td><td>10.2</td><td>Named after <a href="/facts/Llandovery/9YGeGuMX">Llandovery</a>, Wales</td></tr><tr><td><a href="/facts/Upper_Ordovician/BjMrLIEA">Upper Ordovician</a></td><td><a href="https://geoltime.github.io/?Ma=458.2–443.1">458.2 to 443.1</a> million years ago</td><td>15.1</td><td rowspan="3">See <a href="/facts/Ordovician/BjMrLIEA">Ordovician</a></td></tr><tr><td><a href="/facts/Middle_Ordovician/BjMrLIEA">Middle Ordovician</a></td><td><a href="https://geoltime.github.io/?Ma=471.3–458.2">471.3 to 458.2</a> million years ago</td><td>13.1</td></tr><tr><td><a href="/facts/Lower_Ordovician/BjMrLIEA">Lower Ordovician</a></td><td><a href="https://geoltime.github.io/?Ma=486.85–471.3">486.85 to 471.3</a> million years ago</td><td>15.55</td></tr><tr><td><a href="/facts/Furongian/3A6Ke7z5">Furongian</a></td><td><a href="https://geoltime.github.io/?Ma=497–486.85">497 to 486.85</a> million years ago</td><td>10.15</td><td>From Mandarin 芙蓉 (<i>fúróng</i>) 'lotus', referring to the state symbol of <a href="/facts/Hunan/1lbDstf7">Hunan</a></td></tr><tr><td><a href="/facts/Miaolingian/5NcBhyEU">Miaolingian</a></td><td><a href="https://geoltime.github.io/?Ma=506.5–497">506.5 to 497</a> million years ago</td><td>9.5</td><td>Named for the Miao Ling [zh] mountains of <a href="/facts/Guizhou/BWxNrucU">Guizhou</a>, Mandarin for 'sprouting peaks'</td></tr><tr><td><a href="/facts/Cambrian_Series_2/PgmYc09e">Cambrian Series 2</a> (informal)</td><td><a href="https://geoltime.github.io/?Ma=521–506.5">521 to 506.5</a> million years ago</td><td>14.5</td><td>See <a href="/facts/Cambrian/jIfzKtod">Cambrian</a></td></tr><tr><td><a href="/facts/Terreneuvian/wyI3WlUy">Terreneuvian</a></td><td><a href="https://geoltime.github.io/?Ma=538.8–521">538.8 to 521</a> million years ago</td><td>17.8</td><td>Named for <a href="/facts/Terre-Neuve_(New_France)/5xbtMESo">Terre-Neuve</a>, a French <a href="/facts/Calque/A9M3UtAo">calque</a> of <a href="/facts/Newfoundland_(island)/PdfPl9ca">Newfoundland</a></td></tr></tbody></table> <h2 id="history-of-the-geologic-time-scale">History of the geologic time scale</h2> <p class="note">See also: <a href="/facts/History_of_geology/m6xGQNWn">History of geology</a> and <a href="/facts/History_of_paleontology/Ey06mdQD">History of paleontology</a></p> <h3>Early history</h3> <p>The most modern geological time scale was not formulated until 1911<a class="footnote-ref" id="fnref:83" href="#fn:83"><sup>83</sup></a> by <a href="/facts/Arthur_Holmes/RoFQuyRJ">Arthur Holmes</a> (1890 – 1965), who drew inspiration from <a href="/facts/James_Hutton/Y8HUhQIu">James Hutton</a> (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.<a class="footnote-ref" id="fnref:84" href="#fn:84"><sup>84</sup></a> The broader concept of the relation between rocks and time can be traced back to (at least) the <a href="/facts/Philosopher/Hyvzc54m">philosophers</a> of <a href="/facts/Ancient_Greece/PTVBrWXq">Ancient Greece</a> from 1200 BC to 600 AD. <a href="/facts/Xenophanes/aEhw2usQ">Xenophanes of Colophon</a> (c. 570–487 <a href="/facts/Common_era/e5DpqUoe">BCE</a>) 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 <a href="/facts/Marine_transgression/RUuaMyxB">transgressed</a> over the land and at other times had <a href="/facts/Marine_regression/JqF90a93">regressed</a>.<a class="footnote-ref" id="fnref:85" href="#fn:85"><sup>85</sup></a> This view was shared by a few of Xenophanes's scholars and those that followed, including <a href="/facts/Aristotle/U2bDlBFW">Aristotle</a> (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 <a href="/facts/Deep_time/0Pxg29TF">deep time</a> was also recognized by <a href="/facts/History_of_science_and_technology_in_China/JlA3afbj">Chinese naturalist</a> <a href="/facts/Shen_Kuo/GKqhbxHd">Shen Kuo</a><a class="footnote-ref" id="fnref:86" href="#fn:86"><sup>86</sup></a> (1031–1095) and <a href="/facts/Islam/zDLbL45C">Islamic</a> <a href="/facts/Scientist/JDvthEFM">scientist</a>-philosophers, notably the <a href="/facts/Brethren_of_Purity/I5vE6ISa">Brothers of Purity</a>, who wrote on the processes of stratification over the passage of time in their <a href="/facts/Encyclopedia_of_the_Brethren_of_Purity/HyVQBVDl">treatises</a>.<a class="footnote-ref" id="fnref:87" href="#fn:87"><sup>87</sup></a> Their work likely inspired that of the 11th-century <a href="/facts/Persians/4GhM3jl2">Persian</a> <a href="/facts/Polymath/eqIfjQRu">polymath</a> <a href="/facts/Avicenna/EYKG4Vez">Avicenna</a> (Ibn Sînâ, 980–1037) who wrote in <i><a href="/facts/The_Book_of_Healing/gN35JNkD">The Book of Healing</a></i> (1027) on the concept of stratification and superposition, pre-dating <a href="/facts/Nicolas_Steno/mvljqF6d">Nicolas Steno</a> by more than six centuries.<a class="footnote-ref" id="fnref:88" href="#fn:88"><sup>88</sup></a> Avicenna also recognized fossils as "petrifications of the bodies of plants and animals",<a class="footnote-ref" id="fnref:89" href="#fn:89"><sup>89</sup></a> with the 13th-century <a href="/facts/Dominican_Order/n9l5y8Yk">Dominican</a> <a href="/facts/Bishop/n2QGsDWx">bishop</a> <a href="/facts/Albertus_Magnus/12FJVrX9">Albertus Magnus</a> (c. 1200–1280), who drew from <a href="/facts/Aristotle/U2bDlBFW">Aristotle's</a> natural philosophy, extending this into a theory of a petrifying fluid.<a class="footnote-ref" id="fnref:90" href="#fn:90"><sup>90</sup></a> These works appeared to have little influence on <a href="/facts/Scholar/AlNaeFYB">scholars</a> in <a href="/facts/Middle_Ages/RqzEKB9v">Medieval Europe</a> who looked to the <a href="/facts/Bible/SqkRTKCh">Bible</a> to explain the origins of fossils and sea-level changes, often attributing these to the '<a href="/facts/Genesis_flood_narrative/EbjQQLmK">Deluge</a>', including <a href="/facts/Restoro_d%2527Arezzo/uaWu70G9">Ristoro d'Arezzo</a> in 1282.<a class="footnote-ref" id="fnref:91" href="#fn:91"><sup>91</sup></a> It was not until the <a href="/facts/Italian_Renaissance/BqPWuNmz">Italian Renaissance</a> when <a href="/facts/Leonardo_da_Vinci/E83tcPl2">Leonardo da Vinci</a> (1452–1519) would reinvigorate the relationships between stratification, relative sea-level change, and time, denouncing attribution of fossils to the 'Deluge':<a class="footnote-ref" id="fnref:92" href="#fn:92"><sup>92</sup></a><a class="footnote-ref" id="fnref:93" href="#fn:93"><sup>93</sup></a> </p> <blockquote><p>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 neighboring 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.</p></blockquote> <p>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 <a href="/facts/Genesis_creation_narrative/Fy0E2uD8">Genesis</a> were not readily accepted and dissent from <a href="/facts/Religion/cxntrD0R">religious</a> doctrine was in some places unwise, scholars such as <a href="/facts/Girolamo_Fracastoro/tF8SfRzv">Girolamo Fracastoro</a> shared da Vinci's views, and found the attribution of fossils to the 'Deluge' absurd.<a class="footnote-ref" id="fnref:94" href="#fn:94"><sup>94</sup></a> 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."<a class="footnote-ref" id="fnref:95" href="#fn:95"><sup>95</sup></a> Later, in the 19th century, academics further developed theories on stratification. <a href="/facts/William_Smith_(geologist)/3IpguaqC">William Smith</a>, often referred to as the "Father of Geology"<a class="footnote-ref" id="fnref:96" href="#fn:96"><sup>96</sup></a> 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”.<a class="footnote-ref" id="fnref:97" href="#fn:97"><sup>97</sup></a> After studying rock layers and the fossils they contained, <a href="/facts/William_Smith_(geologist)/3IpguaqC">Smith</a> 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.<a class="footnote-ref" id="fnref:98" href="#fn:98"><sup>98</sup></a> 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."<a class="footnote-ref" id="fnref:99" href="#fn:99"><sup>99</sup></a> </p> <h3>Establishment of primary principles</h3> <p>Niels Stensen, more commonly known as Nicolas Steno (1638–1686), is credited with establishing four of the guiding principles of stratigraphy.<a class="footnote-ref" id="fnref:100" href="#fn:100"><sup>100</sup></a> In <i>De solido intra solidum naturaliter contento dissertationis prodromus</i> Steno states:<a class="footnote-ref" id="fnref:101" href="#fn:101"><sup>101</sup></a><a class="footnote-ref" id="fnref:102" href="#fn:102"><sup>102</sup></a> </p> <blockquote> <ul><li>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.</li> <li>... strata which are either perpendicular to the horizon or inclined to it were at one time parallel to the horizon.</li> <li>When any given stratum was being formed, it was either encompassed at its edges by another solid substance or it covered the whole globe of the earth. Hence, it follows that wherever bared edges of strata are seen, either a continuation of the same strata must be looked for or another solid substance must be found that kept the material of the strata from being dispersed.</li> <li>If a body or discontinuity cuts across a stratum, it must have formed after that stratum.</li></ul> </blockquote> <p>Respectively, these are the principles of superposition, original horizontality, lateral continuity, and cross-cutting relationships. From this Steno reasoned that strata were laid down in succession and inferred relative time (in Steno's belief, time from <a href="/facts/Creation_myth/qB15K1b0">Creation</a>). While Steno's principles were simple and attracted much attention, applying them proved challenging.<a class="footnote-ref" id="fnref:103" href="#fn:103"><sup>103</sup></a> These basic principles, albeit with improved and more nuanced interpretations, still form the foundational principles of determining the correlation of strata relative to geologic time. </p><p>Over the course of the 18th-century geologists realised that: </p> <ul><li>Sequences of strata often become eroded, distorted, tilted, or even inverted after deposition</li> <li>Strata laid down at the same time in different areas could have entirely different appearances</li> <li>The strata of any given area represented only part of Earth's long history</li></ul> <h3>Formulation of a modern geologic time scale</h3> <p>The apparent, earliest formal division of the geologic record with respect to time was introduced during the era of Biblical models by <a href="/facts/Thomas_Burnet_(theologian)/edKboSzU">Thomas Burnet</a> who applied a two-fold terminology to mountains by identifying "<i>montes primarii</i>" for rock formed at the time of the 'Deluge', and younger "<i>monticulos secundarios"</i> formed later from the debris of the "<i>primarii"</i>.<a class="footnote-ref" id="fnref:104" href="#fn:104"><sup>104</sup></a><a class="footnote-ref" id="fnref:105" href="#fn:105"><sup>105</sup></a> <a href="/facts/Anton_Moro/WLNhCjPv">Anton Moro</a> (1687–1784) also used primary and secondary divisions for rock units but his mechanism was volcanic.<a class="footnote-ref" id="fnref:106" href="#fn:106"><sup>106</sup></a><a class="footnote-ref" id="fnref:107" href="#fn:107"><sup>107</sup></a> In this early version of the <a href="/facts/Plutonism/XtAmajwq">Plutonism</a> 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 <a href="/facts/Giovanni_Targioni_Tozzetti/g8MuUGk6">Giovanni Targioni Tozzetti</a> (1712–1783) and <a href="/facts/Giovanni_Arduino_(geologist)/40wspMQ8">Giovanni Arduino</a> (1713–1795) to include tertiary and quaternary divisions.<a class="footnote-ref" id="fnref:108" href="#fn:108"><sup>108</sup></a> 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 <a href="/facts/19th_century/6LHXycA8">19th century</a> with a key driver for resolution of this debate being the work of <a href="/facts/James_Hutton/Y8HUhQIu">James Hutton</a> (1726–1797), in particular his <i><a href="/facts/Theory_of_the_Earth/qgCUkvvX">Theory of the Earth</a></i>, first presented before the <a href="/facts/Royal_Society_of_Edinburgh/0U0vEtuK">Royal Society of Edinburgh</a> in 1785.<a class="footnote-ref" id="fnref:109" href="#fn:109"><sup>109</sup></a><a class="footnote-ref" id="fnref:110" href="#fn:110"><sup>110</sup></a><a class="footnote-ref" id="fnref:111" href="#fn:111"><sup>111</sup></a> Hutton's theory would later become known as <a href="/facts/Uniformitarianism/CNs0H7jS">uniformitarianism</a>, popularised by <a href="/facts/John_Playfair/2t52a16I">John Playfair</a><a class="footnote-ref" id="fnref:112" href="#fn:112"><sup>112</sup></a> (1748–1819) and later <a href="/facts/Charles_Lyell/6cAM8yRE">Charles Lyell</a> (1797–1875) in his <i><a href="/facts/Principles_of_Geology/wA3UNkw2">Principles of Geology</a></i>.<a class="footnote-ref" id="fnref:113" href="#fn:113"><sup>113</sup></a><a class="footnote-ref" id="fnref:114" href="#fn:114"><sup>114</sup></a><a class="footnote-ref" id="fnref:115" href="#fn:115"><sup>115</sup></a> Their theories strongly contested the 6,000 year age of the Earth as suggested determined by <a href="/facts/James_Ussher/D0h8gle6">James Ussher</a> 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. </p><p>During the early 19th century <a href="/facts/William_Smith_(geologist)/3IpguaqC">William Smith</a>, <a href="/facts/Georges_Cuvier/4mmE7NzN">Georges Cuvier</a>, <a href="/facts/Jean_Baptiste_Julien_d%2527Omalius_d%2527Halloy/L8RhCCtp">Jean d'Omalius d'Halloy</a>, and <a href="/facts/Alexandre_Brongniart/tDYWo0ob">Alexandre Brongniart</a> 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. </p> <h3>The advent of geochronometry</h3> <p>During the 19th century, the debate regarding Earth's age was renewed, with geologists estimating ages based on <a href="/facts/Denudation/VpfyfhxE">denudation</a> rates and sedimentary thicknesses or ocean chemistry, and physicists determining ages for the cooling of the Earth or the Sun using basic <a href="/facts/Thermodynamics/q4hIx3yP">thermodynamics</a> or orbital physics.<a class="footnote-ref" id="fnref:116" href="#fn:116"><sup>116</sup></a> These estimations varied from 15,000 million years to 0.075 million years depending on method and author, but the estimations of <a href="/facts/William_Thomson%2c_1st_Baron_Kelvin/LTIxG1jV">Lord Kelvin</a> and <a href="/facts/Clarence_King/RtDImDCq">Clarence King</a> 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. </p><p>The discovery of <a href="/facts/Radioactive_decay/Ya6FVjt4">radioactive decay</a> by <a href="/facts/Henri_Becquerel/wN7DSsVL">Henri Becquerel</a>, <a href="/facts/Marie_Curie/EGjeuJ14">Marie Curie</a>, and <a href="/facts/Pierre_Curie/Sbtlw2xj">Pierre Curie</a> 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.<a class="footnote-ref" id="fnref:117" href="#fn:117"><sup>117</sup></a> Early attempts at determining ages of uranium minerals and rocks by <a href="/facts/Ernest_Rutherford/hjjMEskl">Ernest Rutherford</a>, <a href="/facts/Bertram_Boltwood/sWLxNyIE">Bertram Boltwood</a>, <a href="/facts/Robert_Strutt%2c_4th_Baron_Rayleigh/d5novqgh">Robert Strutt</a>, and Arthur Holmes, would culminate in what are considered the first international geological time scales by Holmes in 1911 and 1913.<a class="footnote-ref" id="fnref:118" href="#fn:118"><sup>118</sup></a><a class="footnote-ref" id="fnref:119" href="#fn:119"><sup>119</sup></a><a class="footnote-ref" id="fnref:120" href="#fn:120"><sup>120</sup></a> The discovery of <a href="/facts/Isotope/KD9B1y6o">isotopes</a> in 1913<a class="footnote-ref" id="fnref:121" href="#fn:121"><sup>121</sup></a> by <a href="/facts/Frederick_Soddy/gR9Qk6tc">Frederick Soddy</a>, and the developments in <a href="/facts/Mass_spectrometry/RH5WBHJ2">mass spectrometry</a> pioneered by <a href="/facts/Francis_William_Aston/DVoj9ebB">Francis William Aston</a>, <a href="/facts/Arthur_Jeffrey_Dempster/Ts6YYDM6">Arthur Jeffrey Dempster</a>, and <a href="/facts/Alfred_O._C._Nier/BQl6HzRj">Alfred O. C. Nier</a> during the early to mid-<a href="/facts/20th_century/0Gq5Ivn7">20th century</a> would finally allow for the accurate determination of radiometric ages, with Holmes publishing several revisions to his <i>geological time-scale</i> with his final version in 1960.<a class="footnote-ref" id="fnref:122" href="#fn:122"><sup>122</sup></a><a class="footnote-ref" id="fnref:123" href="#fn:123"><sup>123</sup></a><a class="footnote-ref" id="fnref:124" href="#fn:124"><sup>124</sup></a><a class="footnote-ref" id="fnref:125" href="#fn:125"><sup>125</sup></a> </p> <h3>Modern international geological time scale</h3> <p>The establishment of the IUGS in 1961<a class="footnote-ref" id="fnref:126" href="#fn:126"><sup>126</sup></a> and acceptance of the Commission on Stratigraphy (applied in 1965)<a class="footnote-ref" id="fnref:127" href="#fn:127"><sup>127</sup></a> 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".<a class="footnote-ref" id="fnref:128" href="#fn:128"><sup>128</sup></a> </p><p>Following on from Holmes, several <i>A Geological Time Scale</i> books were published in 1982,<a class="footnote-ref" id="fnref:129" href="#fn:129"><sup>129</sup></a> 1989,<a class="footnote-ref" id="fnref:130" href="#fn:130"><sup>130</sup></a> 2004,<a class="footnote-ref" id="fnref:131" href="#fn:131"><sup>131</sup></a> 2008,<a class="footnote-ref" id="fnref:132" href="#fn:132"><sup>132</sup></a> 2012,<a class="footnote-ref" id="fnref:133" href="#fn:133"><sup>133</sup></a> 2016,<a class="footnote-ref" id="fnref:134" href="#fn:134"><sup>134</sup></a> and 2020.<a class="footnote-ref" id="fnref:135" href="#fn:135"><sup>135</sup></a> 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.<a class="footnote-ref" id="fnref:136" href="#fn:136"><sup>136</sup></a> Subsequent <i>Geologic Time Scale</i> books (2016<a class="footnote-ref" id="fnref:137" href="#fn:137"><sup>137</sup></a> and 2020<a class="footnote-ref" id="fnref:138" href="#fn:138"><sup>138</sup></a>) 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. </p><p>The following five timelines show the geologic time scale to scale. The first shows the entire time from the formation of Earth to the present, but this gives little space for the most recent eon. The second timeline shows an expanded view of the most recent eon. In a similar way, the most recent era is expanded in the third timeline, the most recent period is expanded in the fourth timeline, and the most recent epoch is expanded in the fifth timeline. </p> <p>(Horizontal scale is millions of years for the above timelines; thousands of years for the timeline below) </p> <h2 id="major-proposed-revisions-to-the-icc">Major proposed revisions to the ICC</h2> <h3>Proposed Anthropocene Series/Epoch</h3> <p class="note">Main article: <a href="/facts/Anthropocene/Ex24qeW6">Anthropocene</a></p> <p>First suggested in 2000,<a class="footnote-ref" id="fnref:139" href="#fn:139"><sup>139</sup></a> the <i>Anthropocene</i> 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.<a class="footnote-ref" id="fnref:140" href="#fn:140"><sup>140</sup></a> As of April 2022 the Anthropocene has not been ratified by the ICS; however, in May 2019 the <a href="/facts/Anthropocene_Working_Group/okyscVpW">Anthropocene Working Group</a> voted in favour of submitting a formal proposal to the ICS for the establishment of the Anthropocene Series/Epoch.<a class="footnote-ref" id="fnref:141" href="#fn:141"><sup>141</sup></a> Nevertheless, the definition of the Anthropocene as a geologic time period rather than a geologic event remains controversial and difficult.<a class="footnote-ref" id="fnref:142" href="#fn:142"><sup>142</sup></a><a class="footnote-ref" id="fnref:143" href="#fn:143"><sup>143</sup></a><a class="footnote-ref" id="fnref:144" href="#fn:144"><sup>144</sup></a><a class="footnote-ref" id="fnref:145" href="#fn:145"><sup>145</sup></a> </p> <h3>Proposals for revisions to pre-Cryogenian timeline</h3> <h4>Shields et al. 2021</h4> <p>An international working group of the ICS on pre-Cryogenian chronostratigraphic subdivision have 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.<a class="footnote-ref" id="fnref:146" href="#fn:146"><sup>146</sup></a> This work assessed the geologic history of the currently defined eons and eras of the pre-Cambrian,<a class="footnote-ref" id="fnref:147" href="#fn:147"><sup>147</sup></a> and the proposals in the "Geological Time Scale" books <i>2004,</i><a class="footnote-ref" id="fnref:148" href="#fn:148"><sup>148</sup></a> <i>2012,</i><a class="footnote-ref" id="fnref:149" href="#fn:149"><sup>149</sup></a> and <i>2020.</i><a class="footnote-ref" id="fnref:150" href="#fn:150"><sup>150</sup></a> Their recommend revisions<a class="footnote-ref" id="fnref:151" href="#fn:151"><sup>151</sup></a> of the pre-Cryogenian geologic time scale were (changes from the current scale [v2023/09] are italicised): </p> <ul><li>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. <ul><li>Archean (4000–<i>2450</i> Ma) <ul><li>Paleoarchean (4000–<i>3500</i> Ma)</li> <li>Mesoarchean (<i>3500–3000</i> Ma)</li> <li>Neoarchean (<i>3000–2450</i> Ma) <ul><li><i>Kratian</i> (no fixed time given, prior to the Siderian) – from Greek κράτος (<i>krátos</i>) 'strength'.</li> <li>Siderian (?–<i>2450</i> Ma) – moved from Proterozoic to end of Archean, no start time given, base of Paleoproterozoic defines the end of the Siderian</li></ul></li></ul></li></ul></li> <li>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. <ul><li>Paleoproterozoic (<i>2450–1800</i> Ma) <ul><li><i>Skourian</i> (<i>2450</i>–2300 Ma) – from Greek σκουριά (<i>skouriá</i>) 'rust'.</li> <li>Rhyacian (2300–2050 Ma)</li> <li>Orosirian (2050–1800 Ma)</li></ul></li> <li>Mesoproterozoic (<i>1800</i>–1000 Ma) <ul><li><i>Statherian</i> (1800–1600 Ma)</li> <li>Calymmian (1600–1400 Ma)</li> <li>Ectasian (1400–1200 Ma)</li> <li>Stenian (1200–1000 Ma)</li></ul></li> <li>Neoproterozoic (1000–538.8 Ma)<a class="footnote-ref" id="fnref:152" href="#fn:152"><sup>152</sup></a> <ul><li><i>Kleisian</i> or <i>Syndian</i> (<i>1000–800</i> Ma) – respectively from Greek κλείσιμο (<i>kleísimo</i>) 'closure' and σύνδεση (<i>sýndesi</i>) 'connection'.</li> <li>Tonian (<i>800</i>–720 Ma)</li> <li>Cryogenian (720–635 Ma)</li> <li>Ediacaran (635–538.8 Ma)</li></ul></li></ul></li></ul> <p>Proposed pre-Cambrian timeline (Shield et al. 2021, ICS working group on pre-Cryogenian chronostratigraphy), shown to scale:<a class="footnote-ref" id="fnref:153" href="#fn:153"><sup>153</sup></a> </p> <p>ICC pre-Cambrian timeline (v2024/12, current as of January 2025), shown to scale: </p> <h4>Van Kranendonk et al. 2012 (GTS2012)</h4> <p>The book, <i>Geologic Time Scale 2012,</i> was the last commercial publication of an international chronostratigraphic chart that was closely associated with the ICS.<a class="footnote-ref" id="fnref:154" href="#fn:154"><sup>154</sup></a> It included a proposal to substantially revise the pre-Cryogenian time scale to reflect important events such as the <a href="/facts/Formation_and_evolution_of_the_Solar_System/cgElXHpM">formation of the Solar System</a> and the <a href="/facts/Great_Oxidation_Event/LmTyM8jT">Great Oxidation Event</a>, among others, while at the same time maintaining most of the previous chronostratigraphic nomenclature for the pertinent time span.<a class="footnote-ref" id="fnref:155" href="#fn:155"><sup>155</sup></a> As of April 2022 these proposed changes have not been accepted by the ICS. The proposed changes (changes from the current scale [v2023/09]) are italicised: </p> <ul><li>Hadean Eon (4567<i>–4030</i> Ma) <ul><li><a href="/facts/Chaotian_(geology)/XnumLyxe"><i>Chaotian</i></a> Era/Erathem (<i>4567–4404</i> Ma) – the name alluding both to the <a href="/facts/Chaos_(cosmogony)/54jIl8oM">mythological Chaos</a> and the <a href="/facts/Chaos_theory/LTC17vsF">chaotic</a> phase of <a href="/facts/Planet_formation/IT3D6MpE">planet formation</a>.<a class="footnote-ref" id="fnref:156" href="#fn:156"><sup>156</sup></a><a class="footnote-ref" id="fnref:157" href="#fn:157"><sup>157</sup></a><a class="footnote-ref" id="fnref:158" href="#fn:158"><sup>158</sup></a></li> <li><i>Jack Hillsian</i> or <i>Zirconian</i> Era/Erathem (<i>4404–4030</i> Ma) – both names allude to the Jack Hills Greenstone Belt which provided the oldest mineral grains on Earth, <a href="/facts/Zircon/84APfbLt">zircons</a>.<a class="footnote-ref" id="fnref:159" href="#fn:159"><sup>159</sup></a><a class="footnote-ref" id="fnref:160" href="#fn:160"><sup>160</sup></a></li></ul></li> <li>Archean Eon/Eonothem (<i>4030–2420</i> Ma) <ul><li>Paleoarchean Era/Erathem (<i>4030–3490</i> Ma) <ul><li><i>Acastan</i> Period/System (<i>4030–3810</i> Ma) – named after the <a href="/facts/Acasta_Gneiss/oAcze9EC">Acasta Gneiss</a>, one of the oldest preserved pieces of <a href="/facts/Continental_crust/cGnK3oEr">continental crust</a>.<a class="footnote-ref" id="fnref:161" href="#fn:161"><sup>161</sup></a><a class="footnote-ref" id="fnref:162" href="#fn:162"><sup>162</sup></a></li> <li><i>Isuan</i> Period/System (<i>3810–3490</i> Ma) – named after the <a href="/facts/Isua_Greenstone_Belt/QGMG0uPp">Isua Greenstone Belt</a>.<a class="footnote-ref" id="fnref:163" href="#fn:163"><sup>163</sup></a></li></ul></li> <li>Mesoarchean Era/Erathem (<i>3490–2780</i> Ma) <ul><li><i>Vaalbaran</i> Period/System (<i>3490–3020</i> Ma) – based on the names of the <a href="/facts/Kaapvaal_craton/rBSEJtA3">Kaapvaal</a> (Southern Africa) and <a href="/facts/Pilbara_craton/o3H8Jfa6">Pilbara</a> (Western Australia) <a href="/facts/Craton/fSuY37IC">cratons</a>, to reflect the growth of stable continental nuclei or proto-<a href="/facts/Craton/fSuY37IC">cratonic</a> kernels.<a class="footnote-ref" id="fnref:164" href="#fn:164"><sup>164</sup></a></li> <li><i>Pongolan</i> Period/System (<i>3020–2780</i> Ma) – named after the Pongola Supergroup, in reference to the well preserved evidence of terrestrial microbial communities in those rocks.<a class="footnote-ref" id="fnref:165" href="#fn:165"><sup>165</sup></a></li></ul></li> <li>Neoarchean Era/Erathem (<i>2780–2420</i> Ma) <ul><li><i>Methanian</i> Period/System (<i>2780–2630</i> Ma) – named for the inferred predominance of <a href="/facts/Methanotrophic/fsFp7HDD">methanotrophic</a> <a href="/facts/Prokaryote/oYyvaDDH">prokaryotes</a><a class="footnote-ref" id="fnref:166" href="#fn:166"><sup>166</sup></a></li> <li>Siderian Period/System (<i>2630–2420</i> Ma) – named for the voluminous <a href="/facts/Banded_iron_formation/b1eA2yAk">banded iron formations</a> formed within its duration.<a class="footnote-ref" id="fnref:167" href="#fn:167"><sup>167</sup></a></li></ul></li></ul></li> <li>Proterozoic Eon/Eonothem (<i>2420</i>–538.8 Ma)<a class="footnote-ref" id="fnref:168" href="#fn:168"><sup>168</sup></a> <ul><li>Paleoproterozoic Era/Erathem (<i>2420–1780</i> Ma) <ul><li><i>Oxygenian</i> Period/System (<i>2420–2250</i> Ma) – named for displaying the first evidence for a global oxidising atmosphere.<a class="footnote-ref" id="fnref:169" href="#fn:169"><sup>169</sup></a></li> <li><i>Jatulian</i> or <i>Eukaryian</i> Period/System (<i>2250–2060</i> Ma) – names are respectively for the Lomagundi–Jatuli δ13C isotopic excursion event spanning its duration, and for the (proposed)<a class="footnote-ref" id="fnref:170" href="#fn:170"><sup>170</sup></a><a class="footnote-ref" id="fnref:171" href="#fn:171"><sup>171</sup></a> first fossil appearance of <a href="/facts/Eukaryote/SkwyPLMA">eukaryotes</a>.<a class="footnote-ref" id="fnref:172" href="#fn:172"><sup>172</sup></a></li> <li><i>Columbian Period/System</i> (<i>2060–1780</i> Ma) – named after the <a href="/facts/Supercontinent/amID2KQp">supercontinent</a> <a href="/facts/Columbia_(supercontinent)/o05E63CN">Columbia</a>.<a class="footnote-ref" id="fnref:173" href="#fn:173"><sup>173</sup></a></li></ul></li> <li>Mesoproterozoic Era/Erathem (<i>1780–850</i> Ma) <ul><li><i>Rodinian</i> Period/System (<i>1780–850</i> Ma) – named after the supercontinent <a href="/facts/Rodinia/oBjuSeet">Rodinia</a>, stable environment.<a class="footnote-ref" id="fnref:174" href="#fn:174"><sup>174</sup></a></li></ul></li></ul></li></ul> <p>Proposed pre-Cambrian timeline (GTS2012), shown to scale: </p> <p>ICC pre-Cambrian timeline (v2024/12, current as of January 2025), shown to scale: </p> <h2 id="table-of-geologic-time">Table of geologic time</h2> <p>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 <a href="/facts/Phanerozoic/EKKuYnwl">Phanerozoic</a> Eon looks longer than the rest, it merely spans ~539 million years (~12% of Earth's history), whilst the previous three eons<a class="footnote-ref" id="fnref:175" href="#fn:175"><sup>175</sup></a> collectively span ~3,461 million years (~76% 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).<a class="footnote-ref" id="fnref:176" href="#fn:176"><sup>176</sup></a><a class="footnote-ref" id="fnref:177" href="#fn:177"><sup>177</sup></a> The use of subseries/subepochs has been ratified by the ICS.<a class="footnote-ref" id="fnref:178" href="#fn:178"><sup>178</sup></a> </p><p>While some regional terms are still in use,<a class="footnote-ref" id="fnref:179" href="#fn:179"><sup>179</sup></a> the table of geologic time conforms to the <a href="/facts/Nomenclature/YhTgjjyY">nomenclature</a>, ages, and colour codes set forth by the International Commission on Stratigraphy in the official International Chronostratigraphic Chart.<a class="footnote-ref" id="fnref:180" href="#fn:180"><sup>180</sup></a><a class="footnote-ref" id="fnref:181" href="#fn:181"><sup>181</sup></a> The International Commission on Stratigraphy also provide an online interactive version of this chart. The interactive version is based on a service delivering a machine-readable <a href="/facts/Resource_Description_Framework/WMufyukm">Resource Description Framework</a>/<a href="/facts/Web_Ontology_Language/jkr0IGn8">Web Ontology Language</a> representation of the time scale, which is available through the <a href="/facts/Commission_for_the_Management_and_Application_of_Geoscience_Information/8Wqd6paI">Commission for the Management and Application of Geoscience Information</a> <a href="/facts/GeoSciML/Rp6EPRvU">GeoSciML</a> project as a service<a class="footnote-ref" id="fnref:182" href="#fn:182"><sup>182</sup></a> and at a <a href="/facts/SPARQL/XPP7pFDJ">SPARQL</a> end-point.<a class="footnote-ref" id="fnref:183" href="#fn:183"><sup>183</sup></a><a class="footnote-ref" id="fnref:184" href="#fn:184"><sup>184</sup></a> </p> <table><tbody><tr><th>Eonothem/Eon</th><th>Erathem/Era</th><th>System/Period</th><th>Series/Epoch</th><th>Stage/Age</th><th>Major events</th><th>Start, million years ago<a class="footnote-ref" id="fnref:185" href="#fn:185"><sup>185</sup></a></th></tr><tr><td rowspan="102"><a href="/facts/Phanerozoic/EKKuYnwl">Phanerozoic</a></td><td rowspan="24"><a href="/facts/Cenozoic/yFslcz6n">Cenozoic</a><a class="footnote-ref" id="fnref:186" href="#fn:186"><sup>186</sup></a></td><td rowspan="7"><a href="/facts/Quaternary/3cEgHAqc">Quaternary</a></td><td rowspan="3"><a href="/facts/Holocene/sppPgwW5">Holocene</a></td><td><a href="/facts/Meghalayan/QsRlppAh">Meghalayan</a></td><td><a href="/facts/4.2-kiloyear_event/w0LvDgsV">4.2-kiloyear event</a>, <a href="/facts/Austronesian_peoples/mMTl1M9J">Austronesian expansion</a>, increasing <a href="/facts/Industrial_Revolution/B6E3Fasm">industrial</a> <a href="/facts/Carbon_dioxide_in_the_Earth%2527s_atmosphere/h6A4HSzy">CO2</a>.</td><td>0.0042 *</td></tr><tr><td><a href="/facts/Northgrippian/PtE2GCNr">Northgrippian</a></td><td><a href="/facts/8.2-kiloyear_event/fI8A3uIy">8.2-kiloyear event</a>, <a href="/facts/Holocene_climatic_optimum/tsALYMFp">Holocene climatic optimum</a>. <a href="/facts/Sea_level/mDhuI7Xe">Sea level</a> flooding of <a href="/facts/Doggerland/X49uDaxd">Doggerland</a> and <a href="/facts/Sundaland/C5y3nVce">Sundaland</a>. <a href="/facts/Sahara/JVlJd2VC">Sahara</a> becomes a desert. End of Stone Age and start of <a href="/facts/Recorded_history/pnBxFEvW">recorded history</a>. Humans finally expand into the <a href="/facts/Arctic_Archipelago/M9FjXPrc">Arctic Archipelago</a> and <a href="/facts/Greenland/aagXRTB7">Greenland</a>.</td><td>0.0082 *</td></tr><tr><td><a href="/facts/Greenlandian/gr9BAWXQ">Greenlandian</a></td><td>Climate stabilises. Current <a href="/facts/Interglacial/gKf9Br27">interglacial</a> and <a href="/facts/Holocene_extinction/C1LzDDy7">Holocene extinction</a> begins. <a href="/facts/Neolithic_Revolution/P5tLdcgU">Agriculture begins</a>. Humans spread across the <a href="/facts/Wet_Sahara/jt4CB33R">wet Sahara</a> and <a href="/facts/Arabia/x1fDka2b">Arabia</a>, the <a href="/facts/Extreme_North/4uRefr7D">Extreme North</a>, and the Americas (mainland and the <a href="/facts/Caribbean/zRI9aMCh">Caribbean</a>).</td><td>0.0117 ± 0.000099 *</td></tr><tr><td rowspan="4"><a href="/facts/Pleistocene/0ya9eUp5">Pleistocene</a></td><td><a href="/facts/Late_Pleistocene/jKVh7yXL">Upper/Late</a> <i>('<a href="/facts/Tarantian/jKVh7yXL">Tarantian</a>')</i></td><td><a href="/facts/Eemian/BV8sxf5m">Eemian</a> <a href="/facts/Interglacial/gKf9Br27">interglacial</a>, <a href="/facts/Last_glacial_period/mIYwj8e9">last glacial period</a>, ending with <a href="/facts/Younger_Dryas/q9PFsJ4H">Younger Dryas</a>. <a href="/facts/Toba_catastrophe_theory/3zSPED62">Toba eruption</a>. <a href="/facts/Quaternary_extinction/pMcgaUHC">Pleistocene megafauna (including the last terror birds) extinction</a>. Humans expand into <a href="/facts/Near_Oceania/Mf1ftoWk">Near Oceania</a> and the <a href="/facts/Americas/hEuUTL4K">Americas</a>.</td><td>0.129</td></tr><tr><td><a href="/facts/Chibanian/UIH3W1Uk">Chibanian</a></td><td><a href="/facts/Mid-Pleistocene_Transition/2SGkbWLy">Mid-Pleistocene Transition</a> occurs, high amplitude <a href="/facts/100%2c000-year_problem/0axR63w4">100 ka</a> <a href="/facts/Glacial_period/alIAm38r">glacial cycles</a>. Rise of <a href="/facts/Homo_sapiens/rlcTENsr">Homo sapiens</a>.</td><td>0.774 *</td></tr><tr><td><a href="/facts/Early_Pleistocene/jPp2Cn7a">Calabrian</a></td><td>Further cooling of the climate. Giant <a href="/facts/Terror_birds/2veIN92B">terror birds</a> go extinct. Spread of <a href="/facts/Homo_erectus/5Xqv3CdP">Homo erectus</a> across <a href="/facts/Afro-Eurasia/ADb5HYnJ">Afro-Eurasia</a>.</td><td>1.8 *</td></tr><tr><td><a href="/facts/Gelasian/ebbRUeYv">Gelasian</a></td><td>Start of <a href="/facts/Quaternary_glaciation/5H9xbBTt">Quaternary glaciations</a> and unstable climate.<a class="footnote-ref" id="fnref:187" href="#fn:187"><sup>187</sup></a> Rise of the <a href="/facts/Pleistocene_megafauna/JAhFCTtt">Pleistocene megafauna</a> and <a href="/facts/Homo_habilis/uYFr4tQA">Homo habilis</a>.</td><td>2.58 *</td></tr><tr><td rowspan="8"><a href="/facts/Neogene/zUJxvjuH">Neogene</a></td><td rowspan="2"><a href="/facts/Pliocene/MjcIVQ86">Pliocene</a></td><td><a href="/facts/Piacenzian/HTz5dn47">Piacenzian</a></td><td><a href="/facts/Greenland_ice_sheet/w63939H1">Greenland ice sheet</a> develops<a class="footnote-ref" id="fnref:188" href="#fn:188"><sup>188</sup></a> as the cold slowly intensifies towards the Pleistocene. Atmospheric <a href="/facts/Oxygen/acyn6o8r">O2</a> and CO2 content reaches present-day levels while landmasses also reach their current locations (e.g. the <a href="/facts/Isthmus_of_Panama/tWgYHHak">Isthmus of Panama</a> joins the <a href="/facts/North_America/djNjCQIl">North</a> and <a href="/facts/South_America/PhrFEMk7">South Americas</a>, while allowing <a href="/facts/Great_American_Interchange/e8uuzTok">a faunal interchange</a>). The last non-marsupial metatherians go extinct. <a href="/facts/Australopithecus/hyfqJnsx">Australopithecus</a> common in East Africa; <a href="/facts/Stone_Age/r1KMneWW">Stone Age</a> begins.<a class="footnote-ref" id="fnref:189" href="#fn:189"><sup>189</sup></a></td><td>3.6 *</td></tr><tr><td><a href="/facts/Zanclean/K7mtLXlg">Zanclean</a></td><td><a href="/facts/Zanclean_flood/Gt4MfqE6">Zanclean flooding</a> of the <a href="/facts/Mediterranean_Basin/azjFD5mW">Mediterranean Basin</a>. Cooling climate continues from the Miocene. First <a href="/facts/Equus_(genus)/LARkRzsr">equines</a> and <a href="/facts/Elephantimorpha/YKhYACB2">elephantines</a>. <a href="/facts/Ardipithecus/fKUfolVk">Ardipithecus</a> in Africa.<a class="footnote-ref" id="fnref:190" href="#fn:190"><sup>190</sup></a></td><td>5.333 *</td></tr><tr><td rowspan="6"><a href="/facts/Miocene/cBRRzq4g">Miocene</a></td><td><a href="/facts/Messinian/6YQ8SIhY">Messinian</a></td><td rowspan="2"><a href="/facts/Messinian_Event/4SHUhP49">Messinian Event</a> with hypersaline lakes in empty <a href="/facts/Mediterranean_Basin/azjFD5mW">Mediterranean Basin</a>. Sahara desert formation begins. <a href="/facts/Greenhouse_and_Icehouse_Earth/ENS3leWV">Moderate icehouse climate</a>, punctuated by <a href="/facts/Ice_age/agSMvAgX">ice ages</a> and re-establishment of <a href="/facts/East_Antarctic_Ice_Sheet/8WM0LB6R">East Antarctic Ice Sheet</a>. <a href="/facts/Choristodera/rTolEzdL">Choristoderes</a>, the last non-crocodilian <a href="/facts/Sebecosuchia/D1hMzKrX">crocodylomorphs</a> and <a href="/facts/Creodonta/8QgMQXRq">creodonts</a> go extinct. After <a href="/facts/Gorilla%25E2%2580%2593human_last_common_ancestor/qht13cx6">separating from gorilla ancestors</a>, <a href="/facts/Chimpanzee%25E2%2580%2593human_last_common_ancestor/zm5pcUtw">chimpanzee and human ancestors</a> gradually separate; <a href="/facts/Sahelanthropus/QzgQeYbw">Sahelanthropus</a> and <a href="/facts/Orrorin/xEq31GfA">Orrorin</a> in Africa.</td><td>7.246 *</td></tr><tr><td><a href="/facts/Tortonian/ersx6qwJ">Tortonian</a></td><td>11.63 *</td></tr><tr><td><a href="/facts/Serravallian/rhl1sG8l">Serravallian</a></td><td rowspan="2">Middle Miocene climate optimum temporarily provides a warm climate.<a class="footnote-ref" id="fnref:191" href="#fn:191"><sup>191</sup></a> Extinctions in <a href="/facts/Middle_Miocene_disruption/yM4LtMlJ">middle Miocene disruption</a>, decreasing shark diversity. First <a href="/facts/Hippo/hFGDPWRI">hippos</a>. Ancestor of <a href="/facts/Hominidae/ILn1SYKB">great apes</a>.</td><td>13.82 *</td></tr><tr><td><a href="/facts/Langhian/v1vnPvP0">Langhian</a></td><td>15.98 *</td></tr><tr><td><a href="/facts/Burdigalian/fCahkLGR">Burdigalian</a></td><td rowspan="2"><a href="/facts/Orogeny/XrvRMpsw">Orogeny</a> in <a href="/facts/Northern_Hemisphere/EFwyqL25">Northern Hemisphere</a>. Start of <a href="/facts/Kaikoura_Orogeny/xIV9rw4G">Kaikoura Orogeny</a> forming <a href="/facts/Southern_Alps_in_New_Zealand/FjQQURuc">Southern Alps in New Zealand</a>. Widespread forests slowly <a href="/facts/Photosynthesis/TMV7w693">draw in</a> massive amounts of CO2, gradually lowering the level of atmospheric CO2 from 650 <a href="/facts/Ppmv/PozRuoLM">ppmv</a> down to around 100 ppmv during the Miocene.<a class="footnote-ref" id="fnref:192" href="#fn:192"><sup>192</sup></a><a class="footnote-ref" id="fnref:193" href="#fn:193"><sup>193</sup></a> Modern <a href="/facts/Bird/RJF6zwLP">bird</a> and mammal families become recognizable. The last of the primitive whales go extinct. <a href="/facts/Poaceae/q2CRK8q0">Grasses</a> become ubiquitous. Ancestor of <a href="/facts/Ape/QdTk4pko">apes</a>, including humans.<a class="footnote-ref" id="fnref:194" href="#fn:194"><sup>194</sup></a><a class="footnote-ref" id="fnref:195" href="#fn:195"><sup>195</sup></a> Afro-Arabia collides with Eurasia, fully forming the <a href="/facts/Alpide_Belt/txR9mIBt">Alpide Belt</a> and closing the Tethys Ocean, while allowing a faunal interchange. At the same time, Afro-Arabia splits into <a href="/facts/Africa/XkqQUP9s">Africa</a> and <a href="/facts/Arabian_Plate/sMnNpuC3">West Asia</a>.</td><td>20.45</td></tr><tr><td><a href="/facts/Aquitanian_age/4t4Yjx2F">Aquitanian</a></td><td>23.04 *</td></tr><tr><td rowspan="9"><a href="/facts/Paleogene/CNsEpdA4">Paleogene</a></td><td rowspan="2"><a href="/facts/Oligocene/n3gnNogo">Oligocene</a></td><td><a href="/facts/Chattian/WLk2kdUC">Chattian</a></td><td rowspan="2"><a href="/facts/Eocene%25E2%2580%2593Oligocene_extinction_event/6hoHurAm">Grande Coupure</a> extinction. Start of widespread <a href="/facts/Late_Cenozoic_Ice_Age/KlTTICdq">Antarctic glaciation</a>.<a class="footnote-ref" id="fnref:196" href="#fn:196"><sup>196</sup></a> Rapid <a href="/facts/Evolution/Hj0qAaBk">evolution</a> and diversification of fauna, especially <a href="/facts/Mammal/phSwTzBo">mammals</a> (e.g. first <a href="/facts/Macropodiformes/JE38yFuu">macropods</a> and <a href="/facts/Pinnipedia/8ya4Lzek">seals</a>). Major evolution and dispersal of modern types of <a href="/facts/Flowering_plant/E5eGYIvY">flowering plants</a>. <a href="/facts/Cimolesta/ky2nTFsk">Cimolestans</a>, miacoids and condylarths go extinct. First <a href="/facts/Cetacea/rtC33h63">neocetes</a> (modern, fully aquatic whales) appear.</td><td>27.3 *</td></tr><tr><td><a href="/facts/Rupelian/9o544Kxj">Rupelian</a></td><td>33.9 *</td></tr><tr><td rowspan="4"><a href="/facts/Eocene/EYgI8Uco">Eocene</a></td><td><a href="/facts/Priabonian/5ruB70cv">Priabonian</a></td><td rowspan="3"><a href="/facts/Greenhouse_and_Icehouse_Earth/ENS3leWV">Moderate, cooling climate</a>. Archaic <a href="/facts/Mammal/phSwTzBo">mammals</a> (e.g. <a href="/facts/Creodont/8QgMQXRq">creodonts</a>, <a href="/facts/Miacoidea/lV81aCBv">miacoids</a>, "<a href="/facts/Condylarth/Xre4lxLY">condylarths</a>" etc.) flourish and continue to develop during the epoch. Appearance of several "modern" mammal families. <a href="/facts/Archaeoceti/zCpgSnBM">Primitive whales</a> and <a href="/facts/Sirenia/6KaaDKu5">sea cows</a> diversify after returning to water. <a href="/facts/Bird/RJF6zwLP">Birds</a> continue to diversify. First <a href="/facts/Kelp/XGohrJEJ">kelp</a>, <a href="/facts/Diprotodontia/1eacHjgo">diprotodonts</a>, <a href="/facts/Bear/Y973Q4FP">bears</a> and <a href="/facts/Simian/0vyESHsC">simians</a>. The multituberculates and leptictidans go extinct by the end of the epoch. Reglaciation of Antarctica and formation of its <a href="/facts/Ice_cap/7c6AhKeT">ice cap</a>; End of <a href="/facts/Laramide_Orogeny/QfBCzpss">Laramide</a> and <a href="/facts/Sevier_orogeny/2g14mA1B">Sevier Orogenies</a> of the <a href="/facts/Rocky_Mountains/rDc3cU0E">Rocky Mountains</a> in North America. <a href="/facts/Hellenic_orogeny/ft7PsclA">Hellenic Orogeny</a> begins in Greece and <a href="/facts/Aegean_Sea/Vx4Gg5CT">Aegean Sea</a>.</td><td>37.71 *</td></tr><tr><td><a href="/facts/Bartonian/V2P4JXvq">Bartonian</a></td><td>41.03</td></tr><tr><td><a href="/facts/Lutetian/eFsUX54q">Lutetian</a></td><td>48.07 *</td></tr><tr><td><a href="/facts/Ypresian/KdIvHqv5">Ypresian</a></td><td>Two transient events of global warming (<a href="/facts/Paleocene%25E2%2580%2593Eocene_Thermal_Maximum/QnPVzRR7">PETM</a> and <a href="/facts/Eocene_Thermal_Maximum_2/Gsl1PgQU">ETM-2</a>) and warming climate until the <a href="/facts/Eocene_Climatic_Optimum/EYgI8Uco">Eocene Climatic Optimum</a>. The <a href="/facts/Azolla_event/qA8Kwe42">Azolla event</a> decreased CO2 levels from 3500 <a href="/facts/Parts-per_notation/PozRuoLM">ppm</a> to 650 ppm, setting the stage for a long period of cooling.<a class="footnote-ref" id="fnref:197" href="#fn:197"><sup>197</sup></a><a class="footnote-ref" id="fnref:198" href="#fn:198"><sup>198</sup></a> <a href="/facts/Indian_subcontinent/0XUWGXpx">Greater India</a> collides with Eurasia and starts <a href="/facts/Geology_of_the_Himalaya/aqtb4uDx">Himalayan Orogeny</a> (allowing a <a href="/facts/Biotic_interchange/q0XtCWsK">biotic interchange</a>) while Eurasia completely separates from North America, creating the <a href="/facts/North_Atlantic_Ocean/EI4uChIb">North Atlantic Ocean</a>. <a href="/facts/Maritime_Southeast_Asia/8Jk7HBF6">Maritime Southeast Asia</a> diverges from the rest of Eurasia. First <a href="/facts/Passerine/qby0MANo">passerines</a>, <a href="/facts/Ruminant/tTcBMxk4">ruminants</a>, <a href="/facts/Pangolin/XgTYUFIV">pangolins</a>, <a href="/facts/Bat/CJudzNt1">bats</a> and true <a href="/facts/Primate/Hl8RNE2X">primates</a>.</td><td>56 *</td></tr><tr><td rowspan="3"><a href="/facts/Paleocene/IWWoh8D9">Paleocene</a></td><td><a href="/facts/Thanetian/hFefT8qu">Thanetian</a></td><td rowspan="3">Starts with <a href="/facts/Chicxulub_impact/qVqCqm81">Chicxulub impact</a> and the <a href="/facts/K%25E2%2580%2593Pg_extinction_event/HNyDuEcx">K–Pg extinction event</a>, wiping out all non-avian dinosaurs and pterosaurs, most marine reptiles, many other vertebrates (e.g. many Laurasian metatherians), most cephalopods (only <a href="/facts/Nautilidae/5VgYqgds">Nautilidae</a> and <a href="/facts/Coleoidea/QMkYodBe">Coleoidea</a> survived) and many other invertebrates. <a href="/facts/Greenhouse_and_Icehouse_Earth/ENS3leWV">Climate tropical</a>. <a href="/facts/Mammal/phSwTzBo">Mammals</a> and <a href="/facts/Bird/RJF6zwLP">birds</a> (avians) diversify rapidly into a number of lineages following the extinction event (while the marine revolution stops). Multituberculates and the first <a href="/facts/Rodent/mT4m8QJq">rodents</a> widespread. First large birds (e.g. <a href="/facts/Ratites/sH93ejKd">ratites</a> and <a href="/facts/Terror_birds/2veIN92B">terror birds</a>) and mammals (up to bear or small hippo size). <a href="/facts/Alpine_orogeny/VAkm6zRj">Alpine orogeny</a> in Europe and Asia begins. First <a href="/facts/Proboscidea/Dzk4qsH0">proboscideans</a> and <a href="/facts/Plesiadapiformes/YdYzf4pY">plesiadapiformes</a> (stem primates) appear. <a href="/facts/Australidelphia/gCCyVJ9w">Some marsupials</a> migrate to Australia.</td><td>59.24 *</td></tr><tr><td><a href="/facts/Selandian/x7VrVfgh">Selandian</a></td><td>61.66 *</td></tr><tr><td><a href="/facts/Danian/7kD8PDUv">Danian</a></td><td>66 *</td></tr><tr><td rowspan="30"><a href="/facts/Mesozoic/yYsvXGPa">Mesozoic</a></td><td rowspan="12"><a href="/facts/Cretaceous/nwKtFtKx">Cretaceous</a></td><td rowspan="6"><a href="/facts/Late_Cretaceous/pcHa4fBg">Upper/Late</a></td><td><a href="/facts/Maastrichtian/xRBafamu">Maastrichtian</a></td><td rowspan="12"><a href="/facts/Flowering_plant/E5eGYIvY">Flowering plants</a> proliferate (after developing many features since the Carboniferous), along with new types of <a href="/facts/Insect/IgDNvnUL">insects</a>, while other seed plants (gymnosperms and seed ferns) decline. More modern <a href="/facts/Teleost/1YULPGW5">teleost</a> fish begin to appear. <a href="/facts/Ammonoid/cRCH9GVd">Ammonoids</a>, <a href="/facts/Belemnoidea/hd7Dukb7">belemnites</a>, <a href="/facts/Rudist/WCbDo92y">rudist</a> <a href="/facts/Bivalve/IQDxHVc8">bivalves</a>, <a href="/facts/Sea_urchin/RQrB6XTH">sea urchins</a> and <a href="/facts/Sponge/E9T2WFWA">sponges</a> all common. Many new types of <a href="/facts/Dinosaur/JRdMqBnq">dinosaurs</a> (e.g. <a href="/facts/Tyrannosauridae/6Dm2ljv7">tyrannosaurs</a>, <a href="/facts/Titanosauridae/SNmpPYtf">titanosaurs</a>, <a href="/facts/Hadrosauridae/v4t7JSPB">hadrosaurs</a>, and <a href="/facts/Ceratopsidae/H6zh5uAe">ceratopsids</a>) evolve on land, while <a href="/facts/Crocodilia/G4LbxJs6">crocodilians</a> appear in water and probably cause the last temnospondyls to die out; and <a href="/facts/Mosasaur/73YAcKXd">mosasaurs</a> and modern types of sharks appear in the sea. The revolution started by marine reptiles and sharks reaches its peak, though ichthyosaurs vanish a few million years after being heavily reduced at the <a href="/facts/Bonarelli_Event/Nj3c2N4A">Bonarelli Event</a>. Toothed and <a href="/facts/Neornithes/RJF6zwLP">toothless avian birds</a> coexist with pterosaurs. Modern <a href="/facts/Monotreme/fLMJM4JU">monotremes</a>, <a href="/facts/Metatheria/g4a84l76">metatherian</a> (including <a href="/facts/Marsupial/zN5s4bMq">marsupials</a>, who migrate to South America) and <a href="/facts/Eutheria/3fPKIKxx">eutherian</a> (including <a href="/facts/Placental/xegVWIRG">placentals</a>, <a href="/facts/Leptictida/MglREpnK">leptictidans</a> and <a href="/facts/Cimolesta/ky2nTFsk">cimolestans</a>) mammals appear while the last non-mammalian cynodonts die out. First <a href="/facts/Terrestrial_crab/9v3gel0v">terrestrial crabs</a>. Many snails become terrestrial. Further breakup of Gondwana creates <a href="/facts/South_America/PhrFEMk7">South America</a>, <a href="/facts/Africa/XkqQUP9s">Afro-</a><a href="/facts/West_Asia/xXM15vIz">Arabia</a>, <a href="/facts/Antarctica/bEM5Lem5">Antarctica</a>, <a href="/facts/Oceania/vzTEvsfV">Oceania</a>, <a href="/facts/Madagascar/ez12IAcY">Madagascar</a>, <a href="/facts/Indian_subcontinent/0XUWGXpx">Greater India</a>, and the <a href="/facts/South_Atlantic/EI4uChIb">South Atlantic</a>, <a href="/facts/Indian_Ocean/Kv0crwKG">Indian</a> and <a href="/facts/Antarctic_Ocean/F15W9ADT">Antarctic Oceans</a> and the islands of the Indian (and some of the Atlantic) Ocean. Beginning of <a href="/facts/Laramide_Orogeny/QfBCzpss">Laramide</a> and <a href="/facts/Sevier_Orogeny/2g14mA1B">Sevier Orogenies</a> of the <a href="/facts/Rocky_Mountains/rDc3cU0E">Rocky Mountains</a>. <a href="/facts/Atmosphere_of_Earth/FV97Am25">Atmospheric</a> oxygen and carbon dioxide levels similar to present day. <a href="/facts/Acritarch/jz9WvCfk">Acritarchs</a> disappear. Climate initially warm, but later it cools.</td><td>72.2 ± 0.2 *</td></tr><tr><td><a href="/facts/Campanian/MoPSxcqL">Campanian</a></td><td>83.6 ± 0.2 *</td></tr><tr><td><a href="/facts/Santonian/NWM9bl28">Santonian</a></td><td>85.7 ± 0.2 *</td></tr><tr><td><a href="/facts/Coniacian/qgdmvQJP">Coniacian</a></td><td>89.8 ± 0.3 *</td></tr><tr><td><a href="/facts/Turonian/24S6FAQk">Turonian</a></td><td>93.9 ± 0.2 *</td></tr><tr><td><a href="/facts/Cenomanian/atR50Pe7">Cenomanian</a></td><td>100.5 ± 0.1 *</td></tr><tr><td rowspan="6"><a href="/facts/Early_Cretaceous/5uWEJGYC">Lower/Early</a></td><td><a href="/facts/Albian/faHcmHDC">Albian</a></td><td>~113.2 ± 0.3 *</td></tr><tr><td><a href="/facts/Aptian/nXFfjnyR">Aptian</a></td><td>~121.4 ± 0.6</td></tr><tr><td><a href="/facts/Barremian/sQMx5M6L">Barremian</a></td><td>~125.77 *</td></tr><tr><td><a href="/facts/Hauterivian/WpL9tVoU">Hauterivian</a></td><td>~132.6 ± 0.6 *</td></tr><tr><td><a href="/facts/Valanginian/Xjah8dox">Valanginian</a></td><td>~137.05 ± 0.2 *</td></tr><tr><td><a href="/facts/Berriasian/G3DXzKfj">Berriasian</a></td><td>~143.1 ± 0.6</td></tr><tr><td rowspan="11"><a href="/facts/Jurassic/o5Cy4KzX">Jurassic</a></td><td rowspan="3"><a href="/facts/Late_Jurassic/NzU9rlnL">Upper/Late</a></td><td><a href="/facts/Tithonian/LbjgN2Yj">Tithonian</a></td><td rowspan="11">Climate becomes humid again. <a href="/facts/Gymnosperm/lzcpfbUK">Gymnosperms</a> (especially <a href="/facts/Conifer/vDUgqxCx">conifers</a>, <a href="/facts/Cycad/Kc2JDExr">cycads</a> and <a href="/facts/Cycadeoid/U2QvsBrD">cycadeoids</a>) and <a href="/facts/Fern/e6Cngdyo">ferns</a> common. <a href="/facts/Dinosaur/JRdMqBnq">Dinosaurs</a>, including <a href="/facts/Sauropod/8Iqh2yEJ">sauropods</a>, <a href="/facts/Carnosaur/yau5DVL8">carnosaurs</a>, <a href="/facts/Stegosaur/vLTt2MS1">stegosaurs</a> and <a href="/facts/Coelurosaur/X8HRbjJI">coelurosaurs</a>, become the dominant land vertebrates. Mammals diversify into <a href="/facts/Shuotheriidae/uty9xuu6">shuotheriids</a>, <a href="/facts/Australosphenida/BJAtJNgN">australosphenidans</a>, <a href="/facts/Eutriconodont/vwVCCh22">eutriconodonts</a>, <a href="/facts/Multituberculate/cGr5pfgy">multituberculates</a>, <a href="/facts/Symmetrodont/j3pdCR3v">symmetrodonts</a>, <a href="/facts/Dryolestid/phRjt6GN">dryolestids</a> and <a href="/facts/Boreosphenida/tRFQkzWx">boreosphenidans</a> but mostly remain small. First <a href="/facts/Avialae/0296eLy8">birds</a>, <a href="/facts/Squamata/sM1oc2vj">lizards, snakes</a> and <a href="/facts/Turtle/X0ImnxYt">turtles</a>. First <a href="/facts/Brown_algae/u4PWxxkC">brown algae</a>, <a href="/facts/Batoidea/4w6wfqlh">rays</a>, <a href="/facts/Shrimp/QeWUDe2b">shrimps</a>, <a href="/facts/Crab/GvkhXnSK">crabs</a> and <a href="/facts/Lobster/c5eYu72w">lobsters</a>. <a href="/facts/Parvipelvia/wVcHqQQ9">Parvipelvian</a> ichthyosaurs and <a href="/facts/Plesiosaur/Tbfbj8kH">plesiosaurs</a> diverse. Rhynchocephalians throughout the world. <a href="/facts/Bivalve/IQDxHVc8">Bivalves</a>, <a href="/facts/Ammonoid/cRCH9GVd">ammonoids</a> and <a href="/facts/Belemnoidea/hd7Dukb7">belemnites</a> abundant. <a href="/facts/Sea_urchin/RQrB6XTH">Sea urchins</a> very common, along with <a href="/facts/Crinoid/RlhFVcdX">crinoids</a>, <a href="/facts/Starfish/6JWBux0o">starfish</a>, <a href="/facts/Porifera/E9T2WFWA">sponges</a>, and <a href="/facts/Terebratulida/Rr1F7Ykm">terebratulid</a> and <a href="/facts/Rhynchonellida/vp8DTbRU">rhynchonellid</a> <a href="/facts/Brachiopod/XVBnEPj1">brachiopods</a>. Breakup of <a href="/facts/Pangaea/VGruHKJj">Pangaea</a> into <a href="/facts/Laurasia/GechPqg3">Laurasia</a> and <a href="/facts/Gondwana/zqbAvsnY">Gondwana</a>, with the latter also breaking into two main parts; the <a href="/facts/Pacific/bdxgXRVM">Pacific</a> and <a href="/facts/Arctic_Ocean/l6HS3QyV">Arctic Oceans</a> form. <a href="/facts/Tethys_Ocean/X2b2FIu3">Tethys Ocean</a> forms. <a href="/facts/Nevadan_orogeny/zmsva0A8">Nevadan orogeny</a> in North America. <a href="/facts/Rangitata_Orogeny/j0vVjXXh">Rangitata</a> and <a href="/facts/Cimmerian_Orogeny/MTBLMvsS">Cimmerian orogenies</a> taper off. Atmospheric CO2 levels 3–4 times the present-day levels (1200–1500 ppmv, compared to today's 400 ppmv<a class="footnote-ref" id="fnref:199" href="#fn:199"><sup>199</sup></a><a class="footnote-ref" id="fnref:200" href="#fn:200"><sup>200</sup></a>). <a href="/facts/Crocodylomorph/clPyHg6D">Crocodylomorphs</a> (last pseudosuchians) seek out an aquatic lifestyle. <a href="/facts/Mesozoic_marine_revolution/BnHpEhjk">Mesozoic marine revolution</a> continues from late Triassic. <a href="/facts/Tentaculita/33Wsyz9d">Tentaculitans</a> disappear.</td><td>149.2 ± 0.7</td></tr><tr><td><a href="/facts/Kimmeridgian/rfTuYq4A">Kimmeridgian</a></td><td>154.8 ± 0.8 *</td></tr><tr><td><a href="/facts/Oxfordian_stage/DBshJ2QJ">Oxfordian</a></td><td>161.5 ± 1.0</td></tr><tr><td rowspan="4"><a href="/facts/Middle_Jurassic/3XQSmQgU">Middle</a></td><td><a href="/facts/Callovian/Ye14aMDu">Callovian</a></td><td>165.3 ± 1.1</td></tr><tr><td><a href="/facts/Bathonian/wDyT99az">Bathonian</a></td><td>168.2 ± 1.2 *</td></tr><tr><td><a href="/facts/Bajocian/zP4rvKJW">Bajocian</a></td><td>170.9 ± 0.8 *</td></tr><tr><td><a href="/facts/Aalenian/4TKmCw9L">Aalenian</a></td><td>174.7 ± 0.8 *</td></tr><tr><td rowspan="4"><a href="/facts/Early_Jurassic/atwEBpDz">Lower/Early</a></td><td><a href="/facts/Toarcian/jPtA71Yr">Toarcian</a></td><td>184.2 ± 0.3 *</td></tr><tr><td><a href="/facts/Pliensbachian/MvrKyFML">Pliensbachian</a></td><td>192.9 ± 0.3 *</td></tr><tr><td><a href="/facts/Sinemurian/D1W2Uwd9">Sinemurian</a></td><td>199.5 ± 0.3 *</td></tr><tr><td><a href="/facts/Hettangian/jUx58mIb">Hettangian</a></td><td>201.4 ± 0.2 *</td></tr><tr><td rowspan="7"><a href="/facts/Triassic/r6CNxKXC">Triassic</a></td><td rowspan="3"><a href="/facts/Late_Triassic/TazKYWQN">Upper/Late</a></td><td><a href="/facts/Rhaetian/n7W4IUYz">Rhaetian</a></td><td rowspan="7"><a href="/facts/Archosaur/Urd4MHfp">Archosaurs</a> dominant on land as <a href="/facts/Pseudosuchia/NBGrNAxx">pseudosuchians</a> and in the air as <a href="/facts/Pterosaur/YNQwa1ru">pterosaurs</a>. <a href="/facts/Dinosaur/JRdMqBnq">Dinosaurs</a> also arise from bipedal archosaurs. <a href="/facts/Ichthyosaur/fBNIIJaJ">Ichthyosaurs</a> and <a href="/facts/Nothosaur/HxplIWjW">nothosaurs</a> (a group of sauropterygians) dominate large marine fauna. <a href="/facts/Cynodont/8Trvx14s">Cynodonts</a> become smaller and nocturnal, eventually becoming the first true <a href="/facts/Mammals/phSwTzBo">mammals</a>, while other remaining synapsids die out. <a href="/facts/Rhynchosaur/zG659kMo">Rhynchosaurs</a> (archosaur relatives) also common. <a href="/facts/Seed_ferns/Rq1MDjea">Seed ferns</a> called <i><a href="/facts/Dicroidium/fW0sDDNH">Dicroidium</a></i> remained common in Gondwana, before being replaced by advanced gymnosperms. Many large aquatic <a href="/facts/Temnospondyli/lEoAzjJe">temnospondyl</a> amphibians. <a href="/facts/Ceratitida/ctSEsxgT">Ceratitidan</a> <a href="/facts/Ammonoids/cRCH9GVd">ammonoids</a> extremely common. <a href="/facts/Scleractinia/sIWLzTzm">Modern corals</a> and <a href="/facts/Teleost/1YULPGW5">teleost</a> fish appear, as do many modern <a href="/facts/Insect/IgDNvnUL">insect</a> orders and suborders. First <a href="/facts/Starfish/6JWBux0o">starfish</a>. <a href="/facts/Andes_Mountains/a4wlgG3e">Andean Orogeny</a> in South America. <a href="/facts/Cimmerian_Orogeny/MTBLMvsS">Cimmerian Orogeny</a> in Asia. <a href="/facts/Rangitata_Orogeny/j0vVjXXh">Rangitata Orogeny</a> begins in New Zealand. <a href="/facts/Hunter-Bowen_Orogeny/MLxUTsXC">Hunter-Bowen Orogeny</a> in <a href="/facts/Northern_Australia/Gbshlb2j">Northern Australia</a>, Queensland and <a href="/facts/New_South_Wales/aW7eJXSS">New South Wales</a> ends, (c. 260–225 Ma). <a href="/facts/Carnian_pluvial_event/FLJswrhr">Carnian pluvial event</a> occurs around 234–232 Ma, allowing the first dinosaurs and <a href="/facts/Lepidosaurs/dNGa8jSd">lepidosaurs</a> (including <a href="/facts/Rhynchocephalia/WftNntW9">rhynchocephalians</a>) to radiate. <a href="/facts/Triassic%25E2%2580%2593Jurassic_extinction_event/5XKTUdt6">Triassic–Jurassic extinction event</a> occurs 201 Ma, wiping out all <a href="/facts/Conodonts/wqA7V7cz">conodonts</a> and the <a href="/facts/Procolophonidae/sjyfcL9Y">last parareptiles</a>, many marine reptiles (e.g. all sauropterygians except <a href="/facts/Plesiosaurs/Tbfbj8kH">plesiosaurs</a> and all ichthyosaurs except <a href="/facts/Parvipelvia/wVcHqQQ9">parvipelvians</a>), all <a href="/facts/Crocopoda/8SXBa7y1">crocopodans</a> except crocodylomorphs, pterosaurs, and dinosaurs, and many ammonoids (including the whole <a href="/facts/Ceratitida/ctSEsxgT">Ceratitida</a>), bivalves, brachiopods, corals and sponges. First <a href="/facts/Diatoms/x2oEcP1P">diatoms</a>.<a class="footnote-ref" id="fnref:201" href="#fn:201"><sup>201</sup></a></td><td>~205.7</td></tr><tr><td><a href="/facts/Norian/MtxaHnyD">Norian</a></td><td>~227.3</td></tr><tr><td><a href="/facts/Carnian/DV9VJ0o3">Carnian</a></td><td>~237 *</td></tr><tr><td rowspan="2"><a href="/facts/Middle_Triassic/Y0FBoqA8">Middle</a></td><td><a href="/facts/Ladinian/X9RUy1R2">Ladinian</a></td><td>~241.464 *</td></tr><tr><td><a href="/facts/Anisian/ck89Rqhu">Anisian</a></td><td>246.7</td></tr><tr><td rowspan="2"><a href="/facts/Early_Triassic/oBgudq2V">Lower/Early</a></td><td><a href="/facts/Olenekian/kI4p4QoK">Olenekian</a></td><td>249.9</td></tr><tr><td><a href="/facts/Induan/0xAFy2Iu">Induan</a></td><td>251.902 ± 0.024 *</td></tr><tr><td rowspan="48"><a href="/facts/Paleozoic/5qe2wz7U">Paleozoic</a></td><td rowspan="9"><a href="/facts/Permian/CYgLgu5u">Permian</a></td><td rowspan="2"><a href="/facts/Lopingian/l8Pdcf6k">Lopingian</a></td><td><a href="/facts/Changhsingian/C9MUR4RI">Changhsingian</a></td><td rowspan="9"><a href="/facts/Landmass/Nr31Cq7A">Landmasses</a> unite into <a href="/facts/Supercontinent/amID2KQp">supercontinent</a> <a href="/facts/Pangaea/VGruHKJj">Pangaea</a>, creating the <a href="/facts/Urals/gzNoPkt6">Urals</a>, <a href="/facts/Ouachitas/kWhY0hvr">Ouachitas</a> and <a href="/facts/Appalachian_Mountains/f7X1GBDE">Appalachians</a>, among other mountain ranges (the superocean <a href="/facts/Panthalassa/QKkoYuM3">Panthalassa</a> or Proto-Pacific also forms). End of Permo-Carboniferous glaciation. Hot and dry climate. A possible drop in oxygen levels. <a href="/facts/Synapsida/uzYVtB0F">Synapsids</a> (<a href="/facts/Pelycosaur/hXU6TAxB">pelycosaurs</a> and <a href="/facts/Therapsid/P4ERDjA2">therapsids</a>) become widespread and dominant, while <a href="/facts/Parareptile/mHNswEDB">parareptiles</a> and <a href="/facts/Temnospondyli/lEoAzjJe">temnospondyl</a> <a href="/facts/Amphibian/r2BleD2W">amphibians</a> remain common, with the latter probably giving rise to <a href="/facts/Lissamphibia/zeV5XtE9">modern amphibians</a> in this period. In the mid-Permian, lycophytes are heavily replaced by ferns and seed plants. <a href="/facts/Beetles/hv33fxsL">Beetles</a> and <a href="/facts/Fly/ugzGBFKG">flies</a> evolve. The very large arthropods and non-tetrapod tetrapodomorphs go extinct. Marine life flourishes in warm shallow reefs; <a href="/facts/Productida/QwB4haBq">productid</a> and <a href="/facts/Spiriferida/3jfdgcAI">spiriferid</a> brachiopods, bivalves, <a href="/facts/Foram/8Yo9cPTI">forams</a>, ammonoids (including goniatites), and <a href="/facts/Orthocerida/ggtxlrJj">orthoceridans</a> all abundant. <a href="/facts/Sauria/ywCSP4Nb">Crown reptiles</a> arise from earlier diapsids, and split into the ancestors of <a href="/facts/Lepidosauromorpha/XTcJF6Nu">lepidosaurs</a>, <a href="/facts/Kuehneosauridae/ygL54eaR">kuehneosaurids</a>, <a href="/facts/Choristodera/rTolEzdL">choristoderes</a>, <a href="/facts/Crocopoda/8SXBa7y1">archosaurs</a>, <a href="/facts/Testudinata/R7d1PlXs">testudinatans</a>, <a href="/facts/Ichthyosauromorpha/s8LwKfLr">ichthyosaurs</a>, <a href="/facts/Thalattosaurs/zuzxpyCV">thalattosaurs</a>, and <a href="/facts/Sauropterygia/rBKU42Nd">sauropterygians</a>. Cynodonts evolve from larger therapsids. <a href="/facts/Olson%2527s_Extinction/PbEBYXUQ">Olson's Extinction</a> (273 Ma), <a href="/facts/Capitanian_mass_extinction_event/TGY6H0hr">End-Capitanian extinction</a> (260 Ma), and <a href="/facts/Permian%25E2%2580%2593Triassic_extinction_event/d8kI8Mfn">Permian–Triassic extinction event</a> (252 Ma) occur one after another: more than 80% of life on Earth becomes extinct in the lattermost, including most <a href="/facts/Retaria/8RuMBspr">retarian</a> plankton, corals (<a href="/facts/Tabulata/cKC2PpDL">Tabulata</a> and <a href="/facts/Rugosa/Qd1yG8mw">Rugosa</a> die out fully), brachiopods, bryozoans, gastropods, ammonoids (the goniatites die off fully), insects, parareptiles, synapsids, amphibians, and crinoids (only <a href="/facts/Articulata_(Crinoidea)/cwEItbH1">articulates</a> survived), and all <a href="/facts/Eurypterid/w1GHNTAB">eurypterids</a>, <a href="/facts/Trilobite/Tk8ppaKc">trilobites</a>, <a href="/facts/Graptolite/0kekGhPo">graptolites</a>, <a href="/facts/Hyoliths/0rB1dbKM">hyoliths</a>, <a href="/facts/Edrioasteroidea/o6s4DY8U">edrioasteroid crinozoans</a>, <a href="/facts/Blastoid/wAYJUxXu">blastoids</a> and <a href="/facts/Acanthodians/tshDhfzW">acanthodians</a>. <a href="/facts/Ouachita_Orogeny/r1XkLY71">Ouachita</a> and <a href="/facts/Innuitian_orogeny/Rbx6lQz7">Innuitian orogenies</a> in North America. <a href="/facts/Uralian_orogeny/wAJUolQ0">Uralian orogeny</a> in Europe/Asia tapers off. <a href="/facts/Altai_Mountains/gLRvDcXh">Altaid</a> orogeny in Asia. <a href="/facts/Hunter-Bowen_Orogeny/MLxUTsXC">Hunter-Bowen Orogeny</a> on <a href="/facts/Australia_(continent)/moNlN1Qk">Australian continent</a> begins (c. 260–225 Ma), forming the New England Fold Belt.</td><td>254.14 ± 0.07 *</td></tr><tr><td><a href="/facts/Wuchiapingian/zreCTjlL">Wuchiapingian</a></td><td>259.51 ± 0.21 *</td></tr><tr><td rowspan="3"><a href="/facts/Guadalupian/rsksJLtV">Guadalupian</a></td><td><a href="/facts/Capitanian/6rVQpoEG">Capitanian</a></td><td>264.28 ± 0.16 *</td></tr><tr><td><a href="/facts/Wordian/S5tDbMXm">Wordian</a></td><td>266.9 ± 0.4 *</td></tr><tr><td><a href="/facts/Roadian/I7mnAez4">Roadian</a></td><td>274.4 ± 0.4 *</td></tr><tr><td rowspan="4"><a href="/facts/Cisuralian/DvIWAITS">Cisuralian</a></td><td><a href="/facts/Kungurian/Q9KSdPed">Kungurian</a></td><td>283.3 ± 0.4</td></tr><tr><td><a href="/facts/Artinskian/B6pdcVxf">Artinskian</a></td><td>290.1 ± 0.26 *</td></tr><tr><td><a href="/facts/Sakmarian/klFVozFM">Sakmarian</a></td><td>293.52 ± 0.17 *</td></tr><tr><td><a href="/facts/Asselian/AUuBNC8B">Asselian</a></td><td>298.9 ± 0.15 *</td></tr><tr><td rowspan="7"><a href="/facts/Carboniferous/BRKlkYyd">Carboniferous</a><a class="footnote-ref" id="fnref:202" href="#fn:202"><sup>202</sup></a></td><td rowspan="4"><a href="/facts/Pennsylvanian_(geology)/Fc1LAJSX">Pennsylvanian</a><a class="footnote-ref" id="fnref:203" href="#fn:203"><sup>203</sup></a></td><td><a href="/facts/Gzhelian/SBq1x9zN">Gzhelian</a></td><td rowspan="4"><a href="/facts/Pterygota/Wk2Mdv86">Winged insects</a> radiate suddenly; some (esp. <a href="/facts/Protodonata/eBd85cNT">Protodonata</a> and <a href="/facts/Palaeodictyoptera/H1s6IW4Y">Palaeodictyoptera</a>) of them as well as some <a href="/facts/Millipede/zqL7dyMl">millipedes</a> and <a href="/facts/Scorpion/clJKHDdY">scorpions</a> become very large. First <a href="/facts/Coal/83kV3qxg">coal</a> forests (<a href="/facts/Lepidodendron/x6pArQMq">scale trees</a>, ferns, <a href="/facts/Sigillaria/zwETpw07">club trees</a>, <a href="/facts/Calamites/2kA058Tp">giant horsetails</a>, <i><a href="/facts/Cordaites/Ixp3MC4f">Cordaites</a></i>, etc.). Higher <a href="/facts/Atmosphere_of_Earth/FV97Am25">atmospheric</a> <a href="/facts/Oxygen/acyn6o8r">oxygen</a> levels. <a href="/facts/Permo-Carboniferous/Vm20sbFy">Ice Age</a> continues to the Early Permian. <a href="/facts/Goniatite/vfbyFLvd">Goniatites</a>, brachiopods, bryozoa, bivalves, and corals plentiful in the seas and oceans. First <a href="/facts/Woodlice/ujbDgcRv">woodlice</a>. Testate <a href="/facts/Foram/8Yo9cPTI">forams</a> proliferate. <a href="/facts/Euramerica/GechPqg3">Euramerica</a> collides with <a href="/facts/Gondwana/zqbAvsnY">Gondwana</a> and Siberia-Kazakhstania, the latter of which forms <a href="/facts/Laurasia/GechPqg3">Laurasia</a> and the <a href="/facts/Uralian_orogeny/wAJUolQ0">Uralian orogeny</a>. Variscan orogeny continues (these collisions created orogenies, and ultimately <a href="/facts/Pangaea/VGruHKJj">Pangaea</a>). <a href="/facts/Amphibian/r2BleD2W">Amphibians</a> (e.g. temnospondyls) spread in Euramerica, with some becoming the first <a href="/facts/Amniote/TeLtDTrJ">amniotes</a>. <a href="/facts/Carboniferous_Rainforest_Collapse/Vy6pxKrh">Carboniferous Rainforest Collapse</a> occurs, initiating a dry climate which favors amniotes over amphibians. Amniotes diversify rapidly into <a href="/facts/Synapsids/uzYVtB0F">synapsids</a>, <a href="/facts/Parareptiles/mHNswEDB">parareptiles</a>, <a href="/facts/Captorhinidae/TIAt3FjN">cotylosaurs</a>, <a href="/facts/Protorothyridids/wLYmkWt9">protorothyridids</a> and <a href="/facts/Diapsids/IFjPsvGt">diapsids</a>. <a href="/facts/Rhizodont/jXWxXGz2">Rhizodonts</a> remained common before they died out by the end of the period. First <a href="/facts/Sharks/rh5Cotvx">sharks</a>.</td><td>303.7</td></tr><tr><td><a href="/facts/Kasimovian/BM2BzzBQ">Kasimovian</a></td><td>307 ± 0.1</td></tr><tr><td><a href="/facts/Moscovian_(Carboniferous)/5M9hmAz1">Moscovian</a></td><td>315.2 ± 0.2</td></tr><tr><td><a href="/facts/Bashkirian/TcD4TYta">Bashkirian</a></td><td>323.4 *</td></tr><tr><td rowspan="3"><a href="/facts/Mississippian_(geology)/tqsS6Ifj">Mississippian</a><a class="footnote-ref" id="fnref:204" href="#fn:204"><sup>204</sup></a></td><td><a href="/facts/Serpukhovian/pFpf9wK7">Serpukhovian</a></td><td rowspan="3">Large <a href="/facts/Lycopodiophyta/n3pgWJCH">lycopodian primitive trees</a> flourish and amphibious <a href="/facts/Eurypterid/w1GHNTAB">eurypterids</a> live amid <a href="/facts/Coal/83kV3qxg">coal</a>-forming coastal <a href="/facts/Brackish_water/f6z3UXCa">swamps</a>, radiating significantly one last time. First <a href="/facts/Gymnosperms/lzcpfbUK">gymnosperms</a>. First <a href="/facts/Holometabola/8ErqpgDW">holometabolous</a>, <a href="/facts/Paraneoptera/vGqTXV58">paraneopteran</a>, <a href="/facts/Polyneoptera/z3VMwpy9">polyneopteran</a>, <a href="/facts/Odonatoptera/rY8TnHqm">odonatopteran</a> and <a href="/facts/Ephemeroptera/g2eXU34K">ephemeropteran</a> insects and first <a href="/facts/Barnacles/cF33rlfE">barnacles</a>. First five-digited <a href="/facts/Tetrapods/vWpAxzAW">tetrapods</a> (amphibians) and <a href="/facts/Land_snails/aGk33dhx">land snails</a>. In the oceans, <a href="/facts/Bony_fish/nXoXEj3a">bony</a> and <a href="/facts/Chondrichthyes/xcW7PJDU">cartilaginous fishes</a> are dominant and diverse; <a href="/facts/Echinoderm/j2rd8qwt">echinoderms</a> (especially <a href="/facts/Crinoid/RlhFVcdX">crinoids</a> and <a href="/facts/Blastoid/wAYJUxXu">blastoids</a>) abundant. <a href="/facts/Coral/j7fBLrpw">Corals</a>, <a href="/facts/Bryozoa/obAgpA6M">bryozoans</a>, <a href="/facts/Orthocerida/ggtxlrJj">orthoceridans</a>, <a href="/facts/Goniatite/vfbyFLvd">goniatites</a> and brachiopods (<a href="/facts/Productida/QwB4haBq">Productida</a>, <a href="/facts/Spiriferida/3jfdgcAI">Spiriferida</a>, etc.) recover and become very common again, but <a href="/facts/Trilobita/Tk8ppaKc">trilobites</a> and <a href="/facts/Nautiloid/jvTdn9cr">nautiloids</a> decline. <a href="/facts/Karoo_Ice_Age/jhEJ7pHA">Glaciation</a> in East <a href="/facts/Gondwana/zqbAvsnY">Gondwana</a> continues from Late Devonian. <a href="/facts/Mayor_Island%2fTuhua/QQAPNAoF">Tuhua Orogeny</a> in New Zealand tapers off. Some lobe finned fish called rhizodonts become abundant and dominant in freshwaters. <a href="/facts/Siberia_(continent)/GCGLthTj">Siberia</a> collides with a different small continent, <a href="/facts/Kazakhstania/aIQ7k7wc">Kazakhstania</a>.</td><td>330.3 ± 0.4</td></tr><tr><td><a href="/facts/Vis%25C3%25A9an/H00gMd9o">Viséan</a></td><td>346.7 ± 0.4 *</td></tr><tr><td><a href="/facts/Tournaisian/5fc51hec">Tournaisian</a></td><td>358.86 ± 0.14 *</td></tr><tr><td rowspan="7"><a href="/facts/Devonian/nWgakqzk">Devonian</a></td><td rowspan="2"><a href="/facts/Late_Devonian/nWgakqzk">Upper/Late</a></td><td><a href="/facts/Famennian/1JpyeaRS">Famennian</a></td><td rowspan="7">First <a href="/facts/Lycopodiopsida/YPm8zJq1">lycopods</a>, <a href="/facts/Ferns/e6Cngdyo">ferns</a>, <a href="/facts/Seed_plants/MQBG4KEw">seed plants</a> (<a href="/facts/Seed_ferns/Rq1MDjea">seed ferns</a>, from earlier <a href="/facts/Progymnosperm/macAqmUE">progymnosperms</a>), first trees (the progymnosperm <i><a href="/facts/Archaeopteris/lGD8qM3n">Archaeopteris</a></i>), and first <a href="/facts/Pterygota/Wk2Mdv86">winged insects</a> (palaeoptera and neoptera). <a href="/facts/Strophomenida/Bdtu7LfJ">Strophomenid</a> and <a href="/facts/Atrypa/SQYq6R69">atrypid</a> <a href="/facts/Brachiopod/XVBnEPj1">brachiopods</a>, <a href="/facts/Rugosa/Qd1yG8mw">rugose</a> and <a href="/facts/Tabulata/cKC2PpDL">tabulate</a> corals, and <a href="/facts/Crinoid/RlhFVcdX">crinoids</a> are all abundant in the oceans. First fully coiled cephalopods (<a href="/facts/Ammonoidea/cRCH9GVd">Ammonoidea</a> and <a href="/facts/Nautilida/3AIMkl1b">Nautilida</a>, independently) with the former group very abundant (especially <a href="/facts/Goniatite/vfbyFLvd">goniatites</a>). Trilobites and ostracoderms decline, while jawed fishes (<a href="/facts/Placodermi/kknCSuQ7">placoderms</a>, <a href="/facts/Sarcopterygii/7Glajr07">lobe-finned</a> and <a href="/facts/Actinopterygii/3PNaXXmJ">ray-finned</a> <a href="/facts/Osteichthyes/nXoXEj3a">bony fish</a>, and <a href="/facts/Acanthodians/tshDhfzW">acanthodians</a> and early <a href="/facts/Chondrichthyes/xcW7PJDU">cartilaginous fish</a>) proliferate. Some <a href="/facts/Tetrapodomorpha/rxUSNa98">lobe finned fish</a> transform into digited <a href="/facts/Stegocephalia/7R1oaRKW">fishapods</a>, slowly becoming amphibious. The last non-trilobite artiopods die off. First <a href="/facts/Decapods/MycLb6mz">decapods</a> (like <a href="/facts/Prawns/br8vDAIB">prawns</a>) and <a href="/facts/Isopods/D8SUzdo1">isopods</a>. Pressure from jawed fishes cause eurypterids to decline and <a href="/facts/Coleoidea/QMkYodBe">some cephalopods</a> to lose their shells while anomalocarids vanish. "Old Red Continent" of <a href="/facts/Euramerica/GechPqg3">Euramerica</a> persists after forming in the Caledonian orogeny. Beginning of <a href="/facts/Acadian_Orogeny/mBQAzCeG">Acadian Orogeny</a> for <a href="/facts/Atlas_Mountains/qN0j2DDy">Anti-Atlas Mountains</a> of North Africa, and <a href="/facts/Appalachian_Mountains/f7X1GBDE">Appalachian Mountains</a> of North America, also the <a href="/facts/Antler_Orogeny/KJvIGfE3">Antler</a>, <a href="/facts/Variscan_Orogeny/487yDFUj">Variscan</a>, and <a href="/facts/Mayor_Island%2fTuhua/QQAPNAoF">Tuhua orogenies</a> in New Zealand. A series of extinction events, including the massive <a href="/facts/Kellwasser_event/gkThyMzz">Kellwasser</a> and <a href="/facts/Hangenberg_event/H46E1n4E">Hangenberg</a> ones, wipe out many acritarchs, corals, sponges, molluscs, trilobites, eurypterids, graptolites, brachiopods, crinozoans (e.g. all <a href="/facts/Cystoids/Pav232QK">cystoids</a>), and fish, including all placoderms and ostracoderms.</td><td>372.15 ± 0.46 *</td></tr><tr><td><a href="/facts/Frasnian/A20Pj5QJ">Frasnian</a></td><td>382.31 ± 1.36 *</td></tr><tr><td rowspan="2"><a href="/facts/Middle_Devonian/nWgakqzk">Middle</a></td><td><a href="/facts/Givetian/3RBawbMS">Givetian</a></td><td>387.95 ± 1.04 *</td></tr><tr><td><a href="/facts/Eifelian/wQ2w1a6N">Eifelian</a></td><td>393.47 ± 0.99 *</td></tr><tr><td rowspan="3"><a href="/facts/Early_Devonian/nWgakqzk">Lower/Early</a></td><td><a href="/facts/Emsian/8K9tz6Ub">Emsian</a></td><td>410.62 ± 1.95 *</td></tr><tr><td><a href="/facts/Pragian/KFRr4Ir5">Pragian</a></td><td>413.02 ± 1.91 *</td></tr><tr><td><a href="/facts/Lochkovian/NxcvyLop">Lochkovian</a></td><td>419.62 ± 1.36 *</td></tr><tr><td rowspan="8"><a href="/facts/Silurian/1qx4epPg">Silurian</a></td><td colspan="2"><a href="/facts/Pridoli_epoch/pF1CyLKB">Pridoli</a></td><td rowspan="8"><a href="/facts/Ozone_layer/v4KfjalC">Ozone layer</a> thickens. First <a href="/facts/Vascular_plant/5nWI2huT">vascular plants</a> and fully terrestrialised arthropods: <a href="/facts/Myriapods/JmufXFt7">myriapods</a>, <a href="/facts/Hexapoda/8KKV903Y">hexapods</a> (including <a href="/facts/Insects/IgDNvnUL">insects</a>), and <a href="/facts/Arachnids/xPJbsLga">arachnids</a>. <a href="/facts/Eurypterid/w1GHNTAB">Eurypterids</a> diversify rapidly, becoming widespread and dominant. Cephalopods continue to flourish. True <a href="/facts/Jawed_fish/fN7f8dKQ">jawed fishes</a>, along with <a href="/facts/Ostracoderm/A4p4e6vG">ostracoderms</a>, also roam the seas. <a href="/facts/Tabulate_coral/cKC2PpDL">Tabulate</a> and <a href="/facts/Rugosa/Qd1yG8mw">rugose</a> corals, <a href="/facts/Brachiopod/XVBnEPj1">brachiopods</a> (<i>Pentamerida</i>, <a href="/facts/Rhynchonellida/vp8DTbRU">Rhynchonellida</a>, etc.), <a href="/facts/Cystoids/Pav232QK">cystoids</a> and <a href="/facts/Crinoid/RlhFVcdX">crinoids</a> all abundant. <a href="/facts/Trilobite/Tk8ppaKc">Trilobites</a> and <a href="/facts/Mollusc/1elgknsQ">molluscs</a> diverse; <a href="/facts/Graptolite/0kekGhPo">graptolites</a> not as varied. Three minor extinction events. Some echinoderms go extinct. Beginning of <a href="/facts/Caledonian_Orogeny/MIDhgLhQ">Caledonian Orogeny</a> (collision between Laurentia, Baltica and one of the formerly small Gondwanan terranes) for hills in England, Ireland, Wales, Scotland, and the <a href="/facts/Scandinavian_Mountains/lAWdP0Tr">Scandinavian Mountains</a>. Also continued into Devonian period as the <a href="/facts/Acadian_Orogeny/mBQAzCeG">Acadian Orogeny</a>, above (thus Euramerica forms). <a href="/facts/Taconic_Orogeny/lazhUYNL">Taconic Orogeny</a> tapers off. <a href="/facts/Andean-Saharan_glaciation/7WkBoxUt">Icehouse period</a> ends late in this period after starting in Late Ordovician. <a href="/facts/Lachlan_Orogeny/YhY2hnXr">Lachlan Orogeny</a> on <a href="/facts/Australia_(continent)/moNlN1Qk">Australian continent</a> tapers off.</td><td>422.7 ± 1.6 *</td></tr><tr><td rowspan="2"><a href="/facts/Ludlow_epoch/GPDcYWc8">Ludlow</a></td><td><a href="/facts/Ludfordian/05YJlHxP">Ludfordian</a></td><td>425 ± 1.5 *</td></tr><tr><td><a href="/facts/Gorstian/1CYbkyfr">Gorstian</a></td><td>426.7 ± 1.5 *</td></tr><tr><td rowspan="2"><a href="/facts/Wenlock_epoch/p8uSWFBt">Wenlock</a></td><td><a href="/facts/Homerian/FtyV8lq8">Homerian</a></td><td>430.6 ± 1.3 *</td></tr><tr><td><a href="/facts/Sheinwoodian/ToyVfPKS">Sheinwoodian</a></td><td>432.9 ± 1.2 *</td></tr><tr><td rowspan="3"><a href="/facts/Llandovery_epoch/ITDPljb3">Llandovery</a></td><td><a href="/facts/Telychian/r7tMDkBs">Telychian</a></td><td>438.6 ± 1.0 *</td></tr><tr><td><a href="/facts/Aeronian/LdddgwdJ">Aeronian</a></td><td>440.5 ± 1.0 *</td></tr><tr><td><a href="/facts/Rhuddanian/VXFg8HKC">Rhuddanian</a></td><td>443.1 ± 0.9 *</td></tr><tr><td rowspan="7"><a href="/facts/Ordovician/BjMrLIEA">Ordovician</a></td><td rowspan="3"><a href="/facts/Late_Ordovician/BjMrLIEA">Upper/Late</a></td><td><a href="/facts/Hirnantian/gnAHw02z">Hirnantian</a></td><td rowspan="7">The <a href="/facts/Great_Ordovician_Biodiversification_Event/z6wbnBnq">Great Ordovician Biodiversification Event</a> occurs as plankton increase in number: <a href="/facts/Invertebrate/3CyqCVnN">invertebrates</a> diversify into many new types (especially brachiopods and molluscs; e.g. long <a href="/facts/Orthoconic/54IeWCAR">straight-shelled</a> cephalopods like the long lasting and diverse <a href="/facts/Orthocerida/ggtxlrJj">Orthocerida</a>). Early <a href="/facts/Coral/j7fBLrpw">corals</a>, articulate <a href="/facts/Brachiopod/XVBnEPj1">brachiopods</a> (<i>Orthida</i>, <i>Strophomenida</i>, etc.), <a href="/facts/Bivalves/IQDxHVc8">bivalves</a>, <a href="/facts/Cephalopod/80GlMxHG">cephalopods</a> (nautiloids), <a href="/facts/Trilobite/Tk8ppaKc">trilobites</a>, <a href="/facts/Ostracod/q7ejFS5I">ostracods</a>, <a href="/facts/Bryozoa/obAgpA6M">bryozoans</a>, many types of <a href="/facts/Echinoderms/j2rd8qwt">echinoderms</a> (<a href="/facts/Blastoids/wAYJUxXu">blastoids</a>, <a href="/facts/Cystoids/Pav232QK">cystoids</a>, <a href="/facts/Crinoids/RlhFVcdX">crinoids</a>, <a href="/facts/Sea_urchins/RQrB6XTH">sea urchins</a>, <a href="/facts/Sea_cucumbers/1ruJ7ePx">sea cucumbers</a>, and <a href="/facts/Asterozoa/PJPPB2wm">star-like forms</a>, etc.), branched <a href="/facts/Graptolite/0kekGhPo">graptolites</a>, and other taxa all common. <a href="/facts/Acritarch/jz9WvCfk">Acritarchs</a> still persist and common. Cephalopods become dominant and common, with some trending toward a coiled shell. Anomalocarids decline. Mysterious <a href="/facts/Tentaculita/33Wsyz9d">tentaculitans</a> appear. First <a href="/facts/Eurypterids/w1GHNTAB">eurypterids</a> and <a href="/facts/Ostracoderm/A4p4e6vG">ostracoderm</a> fish appear, the latter probably giving rise to the <a href="/facts/Jawed_fish/fN7f8dKQ">jawed fish</a> at the end of the period. First uncontroversial terrestrial <a href="/facts/Fungi/BHo5DP59">fungi</a> and fully terrestrialised <a href="/facts/Embryophyte/8pzYKGvv">plants</a>. <a href="/facts/Late_Ordovician_glaciation/UvMU1RUh">Ice age</a> at the end of this period, as well as a series of mass <a href="/facts/Late_Ordovician_mass_extinction/jLhHjlPf">extinction events</a>, killing off some cephalopods and many brachiopods, bryozoans, echinoderms, graptolites, trilobites, bivalves, corals and <a href="/facts/Conodonts/wqA7V7cz">conodonts</a>.</td><td>445.2 ± 0.9 *</td></tr><tr><td><a href="/facts/Katian/Es9mBr7j">Katian</a></td><td>452.8 ± 0.7 *</td></tr><tr><td><a href="/facts/Sandbian/VdssCbXJ">Sandbian</a></td><td>458.2 ± 0.7 *</td></tr><tr><td rowspan="2"><a href="/facts/Middle_Ordovician/BjMrLIEA">Middle</a></td><td><a href="/facts/Darriwilian/s1RApoTl">Darriwilian</a></td><td>469.4 ± 0.9 *</td></tr><tr><td><a href="/facts/Dapingian/JDm1GllU">Dapingian</a></td><td>471.3 ± 1.4 *</td></tr><tr><td rowspan="2"><a href="/facts/Early_Ordovician/BjMrLIEA">Lower/Early</a></td><td><a href="/facts/Floian/hqvtex6K">Floian</a>(formerly <a href="/facts/Arenig/bLNRFQgD">Arenig</a>)</td><td>477.1 ± 1.2 *</td></tr><tr><td><a href="/facts/Tremadocian/d3lTcsDl">Tremadocian</a></td><td>486.85 ± 1.5 *</td></tr><tr><td rowspan="10"><a href="/facts/Cambrian/jIfzKtod">Cambrian</a></td><td rowspan="3"><a href="/facts/Furongian/3A6Ke7z5">Furongian</a></td><td><a href="/facts/Cambrian_Stage_10/STVCIqEl">Stage 10</a></td><td rowspan="10">Major diversification of (fossils mainly show bilaterian) life in the <a href="/facts/Cambrian_Explosion/Wg29M7PN">Cambrian Explosion</a> as oxygen levels increase. Numerous fossils; most modern <a href="/facts/Animal/4b8J33nd">animal</a> <a href="/facts/Phylum/ELT3Jyax">phyla</a> (including <a href="/facts/Arthropods/JKJLTFzp">arthropods</a>, <a href="/facts/Mollusca/1elgknsQ">molluscs</a>, <a href="/facts/Annelid/PQvb7NAM">annelids</a>, <a href="/facts/Echinoderm/j2rd8qwt">echinoderms</a>, <a href="/facts/Hemichordate/51nn9BUX">hemichordates</a> and <a href="/facts/Chordate/AldL6ARm">chordates</a>) appear. Reef-building <a href="/facts/Archaeocyatha/GPuEv5wA">archaeocyathan</a> sponges initially abundant, then vanish. Stromatolites replace them, but quickly fall prey to the <a href="/facts/Agronomic_revolution/VXyxVv9g">Agronomic revolution</a>, when some animals started burrowing through the microbial mats (affecting some other animals as well). First <a href="/facts/Artiopods/6l0KmnYa">artiopods</a> (including <a href="/facts/Trilobite/Tk8ppaKc">trilobites</a>), <a href="/facts/Priapulid/Bm3KobUK">priapulid</a> worms, inarticulate <a href="/facts/Brachiopod/XVBnEPj1">brachiopods</a> (unhinged lampshells), <a href="/facts/Hyoliths/0rB1dbKM">hyoliths</a>, <a href="/facts/Bryozoa/obAgpA6M">bryozoans</a>, <a href="/facts/Graptolite/0kekGhPo">graptolites</a>, pentaradial echinoderms (e.g. <a href="/facts/Blastozoa/6rdMwgce">blastozoans</a>, <a href="/facts/Crinozoa/X9swAWmE">crinozoans</a> and <a href="/facts/Eleutherozoa/uCFTuQNA">eleutherozoans</a>), and numerous other animals. <a href="/facts/Anomalocarid/jeYIh4TS">Anomalocarids</a> are dominant and giant predators, while <a href="/facts/End-Ediacaran_extinction/kyXWQyFf">many Ediacaran fauna die out</a>. <a href="/facts/Crustacea/PBobIVJP">Crustaceans</a> and molluscs diversify rapidly. <a href="/facts/Prokaryote/oYyvaDDH">Prokaryotes</a>, <a href="/facts/Protist/NYVfaGVz">protists</a> (e.g., <a href="/facts/Foram/8Yo9cPTI">forams</a>), <a href="/facts/Algae/U1ftVKU3">algae</a> and <a href="/facts/Fungi/BHo5DP59">fungi</a> continue to present day. First <a href="/facts/Vertebrate/tT54FSTT">vertebrates</a> from earlier chordates. <a href="/facts/Petermann_Orogeny/zvb2PXsv">Petermann Orogeny</a> on the <a href="/facts/Australia_(continent)/moNlN1Qk">Australian continent</a> tapers off (550–535 Ma). Ross Orogeny in Antarctica. <a href="/facts/Delamerian_Orogeny/HrQthTEx">Delamerian Orogeny</a> (c. 514–490 Ma) on <a href="/facts/Australia_(continent)/moNlN1Qk">Australian continent</a>. Some small terranes split off from Gondwana. <a href="/facts/Atmosphere_of_Earth/FV97Am25">Atmospheric</a> CO2 content roughly 15 times present-day (<a href="/facts/Holocene/sppPgwW5">Holocene</a>) levels (6000 ppm compared to today's 400 ppm)<a class="footnote-ref" id="fnref:205" href="#fn:205"><sup>205</sup></a><a class="footnote-ref" id="fnref:206" href="#fn:206"><sup>206</sup></a> <a href="/facts/Arthropod/JKJLTFzp">Arthropods</a> and <a href="/facts/Embryophyte/8pzYKGvv">streptophyta</a> start colonising land. 3 extinction events occur 517, 502 and 488 Ma, the <a href="/facts/End-Botomian_mass_extinction/NQGXmgwP">first</a> and <a href="/facts/Cambrian%25E2%2580%2593Ordovician_extinction_event/64uek6sd">last</a> of which wipe out many of the anomalocarids, artiopods, hyoliths, brachiopods, molluscs, and conodonts (early jawless vertebrates).</td><td>~491</td></tr><tr><td><a href="/facts/Jiangshanian/Ymsqbkfz">Jiangshanian</a></td><td>~494.2 *</td></tr><tr><td><a href="/facts/Paibian/Dr1U9pT9">Paibian</a></td><td>~497 *</td></tr><tr><td rowspan="3"><a href="/facts/Miaolingian/5NcBhyEU">Miaolingian</a></td><td><a href="/facts/Guzhangian/FadkEIX7">Guzhangian</a></td><td>~500.5 *</td></tr><tr><td><a href="/facts/Drumian/kavls53N">Drumian</a></td><td>~504.5 *</td></tr><tr><td><a href="/facts/Wuliuan/6hYjy35q">Wuliuan</a></td><td>~506.5</td></tr><tr><td rowspan="2"><a href="/facts/Cambrian_Series_2/PgmYc09e">Series 2</a></td><td><a href="/facts/Cambrian_Stage_4/LQd79pjc">Stage 4</a></td><td>~514.5</td></tr><tr><td><a href="/facts/Cambrian_Stage_3/vpWqwBov">Stage 3</a></td><td>~521</td></tr><tr><td rowspan="2"><a href="/facts/Terreneuvian/wyI3WlUy">Terreneuvian</a></td><td><a href="/facts/Cambrian_Stage_2/04hjVyHJ">Stage 2</a></td><td>~529</td></tr><tr><td><a href="/facts/Fortunian/mzHhskWD">Fortunian</a></td><td>538.8 ± 0.6 *</td></tr><tr><td rowspan="10"><a href="/facts/Proterozoic/sSGXxqUU">Proterozoic</a></td><td rowspan="3"><a href="/facts/Neoproterozoic/89NsnsM1">Neoproterozoic</a></td><td><a href="/facts/Ediacaran/z8jSUITT">Ediacaran</a></td><td colspan="3">Good <a href="/facts/Fossil/by7NzIA1">fossils</a> of primitive <a href="/facts/Animal/4b8J33nd">animals</a>. <a href="/facts/Ediacaran_biota/1lx1CXxT">Ediacaran biota</a> flourish worldwide in seas, possibly appearing after an <a href="/facts/Avalon_explosion/YCLcTMsW">explosion</a>, possibly caused by a large-scale oxidation event.<a class="footnote-ref" id="fnref:207" href="#fn:207"><sup>207</sup></a> First <a href="/facts/Vendozoa/1lx1CXxT">vendozoans</a> (unknown affinity among animals), <a href="/facts/Cnidaria/d0HRc6w0">cnidarians</a> and <a href="/facts/Bilateria/nfUwVYrx">bilaterians</a>. Enigmatic vendozoans include many soft-jellied creatures shaped like bags, disks, or quilts (like <i><a href="/facts/Dickinsonia/Rs0Eqyco">Dickinsonia</a></i>). Simple <a href="/facts/Trace_fossil/kaucgzNj">trace fossils</a> of possible worm-like <i><a href="/facts/Trichophycus_pedum/cFHujJX1">Trichophycus</a></i>, etc. <a href="/facts/Taconic_Orogeny/lazhUYNL">Taconic Orogeny</a> in North America. <a href="/facts/Aravalli_Range/c0kCkuMH">Aravalli Range</a> <a href="/facts/Orogeny/XrvRMpsw">orogeny</a> in <a href="/facts/Indian_subcontinent/0XUWGXpx">Indian subcontinent</a>. Beginning of <a href="/facts/Pan-African_Orogeny/L5vcdAdY">Pan-African Orogeny</a>, leading to the formation of the short-lived Ediacaran supercontinent <a href="/facts/Pannotia/ulmTgITg">Pannotia</a>, which by the end of the period breaks up into <a href="/facts/Laurentia/G54C2qc3">Laurentia</a>, <a href="/facts/Baltica/RvuQJgSd">Baltica</a>, <a href="/facts/Siberia_(continent)/GCGLthTj">Siberia</a> and <a href="/facts/Gondwana/zqbAvsnY">Gondwana</a>. <a href="/facts/Petermann_Orogeny/zvb2PXsv">Petermann Orogeny</a> forms on <a href="/facts/Australia_(continent)/moNlN1Qk">Australian continent</a>. Beardmore Orogeny in Antarctica, 633–620 Ma. <a href="/facts/Ozone_layer/v4KfjalC">Ozone layer</a> forms. An increase in oceanic <a href="/facts/Mineral/LkUFbNmv">mineral</a> levels.</td><td>~635 *</td></tr><tr><td><a href="/facts/Cryogenian/5NxvCx4r">Cryogenian</a></td><td colspan="3">Possible "<a href="/facts/Snowball_Earth/A9yP3khz">Snowball Earth</a>" period. <a href="/facts/Fossil/by7NzIA1">Fossils</a> still rare. Late Ruker / Nimrod Orogeny in Antarctica tapers off. First uncontroversial <a href="/facts/Sponge/E9T2WFWA">animal</a> fossils. First hypothetical <a href="/facts/Amastigomycota/VexSQDeL">terrestrial fungi</a><a class="footnote-ref" id="fnref:208" href="#fn:208"><sup>208</sup></a> and <a href="/facts/Streptophyta/wxux2Xnp">streptophyta</a>.<a class="footnote-ref" id="fnref:209" href="#fn:209"><sup>209</sup></a></td><td>~720</td></tr><tr><td><a href="/facts/Tonian/qkGE6hCf">Tonian</a></td><td colspan="3">Final assembly of <a href="/facts/Rodinia/oBjuSeet">Rodinia</a> supercontinent occurs in early Tonian, with breakup beginning c. 800 Ma. <a href="/facts/Sveconorwegian_orogeny/I90hp2EG">Sveconorwegian orogeny</a> ends. <a href="/facts/Grenville_Orogeny/DwY0Jjv7">Grenville Orogeny</a> tapers off in North America. Lake Ruker / Nimrod Orogeny in Antarctica, 1,000 ± 150 Ma. Edmundian Orogeny (c. 920–850 Ma), <a href="/facts/Gascoyne_Complex/9koaBcxU">Gascoyne Complex</a>, Western Australia. Deposition of <a href="/facts/Adelaide_Superbasin/HrQthTEx">Adelaide Superbasin</a> and <a href="/facts/Centralian_Superbasin/0FQXvbcP">Centralian Superbasin</a> begins on <a href="/facts/Australia_(continent)/moNlN1Qk">Australian continent</a>. First hypothetical <a href="/facts/Animals/4b8J33nd">animals</a> (from holozoans) and terrestrial algal mats. Many endosymbiotic events concerning red and green algae occur, transferring plastids to <a href="/facts/Ochrophyta/1kduBajE">ochrophyta</a> (e.g. <a href="/facts/Diatoms/x2oEcP1P">diatoms</a>, <a href="/facts/Brown_algae/u4PWxxkC">brown algae</a>), <a href="/facts/Dinoflagellate/jcQuSgM3">dinoflagellates</a>, <a href="/facts/Cryptophyta/guPlu4Rw">cryptophyta</a>, <a href="/facts/Haptophyta/6orzeYF4">haptophyta</a>, and <a href="/facts/Euglenid/xotTtPM7">euglenids</a> (the events may have begun in the Mesoproterozoic)<a class="footnote-ref" id="fnref:210" href="#fn:210"><sup>210</sup></a> while the first <a href="/facts/Retaria/8RuMBspr">retarians</a> (e.g. <a href="/facts/Forams/8Yo9cPTI">forams</a>) also appear: eukaryotes diversify rapidly, including algal, eukaryovoric and <a href="/facts/Biomineralization/m5mGPaTM">biomineralised</a> forms. <a href="/facts/Trace_fossil/kaucgzNj">Trace fossils</a> of simple <a href="/facts/Multicellular/rk8QBF7o">multi-celled</a> eukaryotes. <a href="/facts/Neoproterozoic_oxygenation_event/St3FvUDf">Neoproterozoic oxygenation event</a> (NOE), 850–540 Ma.<a class="footnote-ref" id="fnref:211" href="#fn:211"><sup>211</sup></a></td><td>1000 <a class="footnote-ref" id="fnref:212" href="#fn:212"><sup>212</sup></a></td></tr><tr><td rowspan="3"><a href="/facts/Mesoproterozoic/bJ8uWQUH">Mesoproterozoic</a></td><td><a href="/facts/Stenian/JJ5tA2K1">Stenian</a></td><td colspan="3">Narrow highly <a href="/facts/Metamorphic_rock/JRp6dsCm">metamorphic</a> belts due to <a href="/facts/Orogeny/XrvRMpsw">orogeny</a> as <a href="/facts/Rodinia/oBjuSeet">Rodinia</a> forms, surrounded by the <a href="/facts/Pan-African_Ocean/vs9v0zqs">Pan-African Ocean</a>. <a href="/facts/Sveconorwegian_orogeny/I90hp2EG">Sveconorwegian orogeny</a> starts. Late Ruker / Nimrod Orogeny in Antarctica possibly begins. Musgrave Orogeny (c. 1,080–), <a href="/facts/Musgrave_Block/G068anoK">Musgrave Block</a>, <a href="/facts/Central_Australia/rBGBkLHj">Central Australia</a>. <a href="/facts/Stromatolite/Wr208p5m">Stromatolites</a> decline as <a href="/facts/Algae/U1ftVKU3">algae</a> proliferate.</td><td>1200 <a class="footnote-ref" id="fnref:213" href="#fn:213"><sup>213</sup></a></td></tr><tr><td><a href="/facts/Ectasian/59eN5AKF">Ectasian</a></td><td colspan="3"><a href="/facts/Platform_cover/CSe6r4S5">Platform covers</a> continue to expand. <a href="/facts/Alga/U1ftVKU3">Algal</a> <a href="/facts/Colony_(biology)/b5QfltwY">colonies</a> in the seas. <a href="/facts/Grenville_Orogeny/DwY0Jjv7">Grenville Orogeny</a> in North America. Columbia breaks up.</td><td>1400 <a class="footnote-ref" id="fnref:214" href="#fn:214"><sup>214</sup></a></td></tr><tr><td><a href="/facts/Calymmian/kEjss5Ve">Calymmian</a></td><td colspan="3"><a href="/facts/Platform_cover/CSe6r4S5">Platform covers</a> expand. Barramundi Orogeny, <a href="/facts/McArthur_Basin/C2vgd1qa">McArthur Basin</a>, <a href="/facts/Northern_Australia/Gbshlb2j">Northern Australia</a>, and Isan Orogeny, c. 1,600 Ma, Mount Isa Block, Queensland. First <a href="/facts/Archaeplastida/64UGVyKu">archaeplastidans</a> (the first eukaryotes with <a href="/facts/Plastids/INesmXK7">plastids</a> from cyanobacteria; e.g. <a href="/facts/Red_algae/jCeIc7Kq">red</a> and <a href="/facts/Green_algae/3NlQ6pKF">green algae</a>) and <a href="/facts/Opisthokonts/y2AkoxVG">opisthokonts</a> (giving rise to the first <a href="/facts/Fungi/BHo5DP59">fungi</a> and <a href="/facts/Holozoa/ay3uYhgc">holozoans</a>). <a href="/facts/Acritarch/jz9WvCfk">Acritarchs</a> (remains of marine algae possibly) start appearing in the fossil record.</td><td>1600 <a class="footnote-ref" id="fnref:215" href="#fn:215"><sup>215</sup></a></td></tr><tr><td rowspan="4"><a href="/facts/Paleoproterozoic/gMS69p5r">Paleoproterozoic</a></td><td><a href="/facts/Statherian/LHcg66kG">Statherian</a></td><td colspan="3">First uncontroversial <a href="/facts/Eukaryotes/SkwyPLMA">eukaryotes</a>: <a href="/facts/Protist/NYVfaGVz">protists</a> with nuclei and endomembrane system. <a href="/facts/Columbia_(supercontinent)/o05E63CN">Columbia</a> forms as the second undisputed earliest supercontinent. Kimban Orogeny in Australian continent ends. Yapungku Orogeny on <a href="/facts/Yilgarn_craton/pGQqkfQH">Yilgarn craton</a>, in Western Australia. Mangaroon Orogeny, 1,680–1,620 Ma, on the <a href="/facts/Gascoyne_Complex/9koaBcxU">Gascoyne Complex</a> in Western Australia. Kararan Orogeny (1,650 Ma), Gawler craton, <a href="/facts/South_Australia/R7UdxV97">South Australia</a>. Oxygen levels drop again.</td><td>1800 <a class="footnote-ref" id="fnref:216" href="#fn:216"><sup>216</sup></a></td></tr><tr><td><a href="/facts/Orosirian/dajazQeI">Orosirian</a></td><td colspan="3">The <a href="/facts/Atmosphere_of_Earth/FV97Am25">atmosphere</a> becomes much more <a href="/facts/Oxygen/acyn6o8r">oxygenic</a> while more cyanobacterial stromatolites appear. <a href="/facts/Vredefort_impact_structure/affD6ltj">Vredefort</a> and <a href="/facts/Sudbury_Basin/poJSD267">Sudbury Basin</a> asteroid impacts. Much <a href="/facts/Orogeny/XrvRMpsw">orogeny</a>. <a href="/facts/Penokean_orogeny/MAz2a886">Penokean</a> and <a href="/facts/Trans-Hudsonian_Orogeny/j4MBJzgt">Trans-Hudsonian Orogenies</a> in North America. Early Ruker Orogeny in Antarctica, 2,000–1,700 Ma. Glenburgh Orogeny, <a href="/facts/Gascoyne_Complex/9koaBcxU">Glenburgh Terrane</a>, <a href="/facts/Australia_(continent)/moNlN1Qk">Australian continent</a> c. 2,005–1,920 Ma. Kimban Orogeny, <a href="/facts/Gawler_craton/tS9ec7Rw">Gawler craton</a> in Australian continent begins.</td><td>2050 <a class="footnote-ref" id="fnref:217" href="#fn:217"><sup>217</sup></a></td></tr><tr><td><a href="/facts/Rhyacian/3IYRSHxd">Rhyacian</a></td><td colspan="3"><a href="/facts/Bushveld_Igneous_Complex/pGdEX95A">Bushveld Igneous Complex</a> forms. <a href="/facts/Huronian/SxGpeQ1p">Huronian</a> glaciation. First hypothetical <a href="/facts/Eukaryote/SkwyPLMA">eukaryotes</a>. Multicellular <a href="/facts/Francevillian_biota/m5D0Svmm">Francevillian biota</a>. Kenorland disassembles.</td><td>2300 <a class="footnote-ref" id="fnref:218" href="#fn:218"><sup>218</sup></a></td></tr><tr><td><a href="/facts/Siderian/7aspCrFn">Siderian</a></td><td colspan="3"><a href="/facts/Great_Oxidation_Event/LmTyM8jT">Great Oxidation Event</a> (due to <a href="/facts/Cyanobacteria/S8bKxIU9">cyanobacteria</a>) increases oxygen. Sleaford Orogeny on <a href="/facts/Australia_(continent)/moNlN1Qk">Australian continent</a>, <a href="/facts/Gawler_craton/tS9ec7Rw">Gawler craton</a> 2,440–2,420 Ma.</td><td>2500 <a class="footnote-ref" id="fnref:219" href="#fn:219"><sup>219</sup></a></td></tr><tr><td rowspan="4"><a href="/facts/Archean/PHt8Sm8n">Archean</a></td><td><a href="/facts/Neoarchean/fCh6XLKA">Neoarchean</a></td><td colspan="4">Stabilization of most modern <a href="/facts/Craton/fSuY37IC">cratons</a>; possible <a href="/facts/Mantle_(geology)/RpDdtjCr">mantle</a> overturn event. Insell Orogeny, 2,650 ± 150 Ma. <a href="/facts/Abitibi_greenstone_belt/XCADzWL3">Abitibi greenstone belt</a> in present-day <a href="/facts/Ontario/HUkxk5Rf">Ontario</a> and <a href="/facts/Quebec/4hhNvb4t">Quebec</a> begins to form, stabilises by 2,600 Ma. First uncontroversial <a href="/facts/Supercontinent/amID2KQp">supercontinent</a>, <a href="/facts/Kenorland/Q5qD2w7j">Kenorland</a>, and first terrestrial <a href="/facts/Prokaryotes/oYyvaDDH">prokaryotes</a>.</td><td>2800 <a class="footnote-ref" id="fnref:220" href="#fn:220"><sup>220</sup></a></td></tr><tr><td><a href="/facts/Mesoarchean/jsK450vc">Mesoarchean</a></td><td colspan="4">First <a href="/facts/Stromatolite/Wr208p5m">stromatolites</a> (probably <a href="/facts/Colony_(biology)/b5QfltwY">colonial</a> phototrophic bacteria, like cyanobacteria). Oldest <a href="/facts/Macrofossil/TKBySXyG">macrofossils</a>. Humboldt Orogeny in Antarctica. <a href="/facts/Blake_River_Megacaldera_Complex/cazKB2go">Blake River Megacaldera Complex</a> begins to form in present-day <a href="/facts/Ontario/HUkxk5Rf">Ontario</a> and <a href="/facts/Quebec/4hhNvb4t">Quebec</a>, ends by roughly 2,696 Ma.</td><td>3200 <a class="footnote-ref" id="fnref:221" href="#fn:221"><sup>221</sup></a></td></tr><tr><td><a href="/facts/Paleoarchean/5cldXjwo">Paleoarchean</a></td><td colspan="4">Prokaryotic <a href="/facts/Archaea/Adxh0aHw">archaea</a> (e.g. <a href="/facts/Methanogens/6tRT6LyH">methanogens</a>) and <a href="/facts/Bacteria/wC8xSCsU">bacteria</a> (e.g. <a href="/facts/Cyanobacteria/S8bKxIU9">cyanobacteria</a>) diversify rapidly, along with early <a href="/facts/Viruses/mf88Bcbl">viruses</a>. First known <a href="/facts/Phototroph/g8gH5q72">phototrophic</a> <a href="/facts/Bacteria/wC8xSCsU">bacteria</a>. Oldest definitive <a href="/facts/Microfossils/PfE0lu1n">microfossils</a>. First <a href="/facts/Microbial_mats/qVfYYzvW">microbial mats</a>. Oldest <a href="/facts/Craton/fSuY37IC">cratons</a> on Earth (such as the <a href="/facts/Canadian_Shield/TklzY7Ln">Canadian Shield</a> and the <a href="/facts/Pilbara_craton/o3H8Jfa6">Pilbara Craton</a>) may have formed during this period.<a class="footnote-ref" id="fnref:222" href="#fn:222"><sup>222</sup></a> Rayner Orogeny in Antarctica.</td><td>3600 <a class="footnote-ref" id="fnref:223" href="#fn:223"><sup>223</sup></a></td></tr><tr><td><a href="/facts/Eoarchean/q7KzQNHD">Eoarchean</a></td><td colspan="4">First uncontroversial <a href="/facts/Life/DNw7NUId">living organisms</a>: at first <a href="/facts/Protocell/73len3AA">protocells</a> with <a href="/facts/RNA_world/o9qmTdd1">RNA-based genes</a> around 4000 Ma, after which true <a href="/facts/Cell_(biology)/bLM9UQvy">cells</a> (<a href="/facts/Prokaryote/oYyvaDDH">prokaryotes</a>) evolve along with <a href="/facts/Proteins/Jxmagu3E">proteins</a> and <a href="/facts/DNA/nB89Iauz">DNA</a>-based genes around 3800 Ma. The end of the <a href="/facts/Late_Heavy_Bombardment/PBUlnPJX">Late Heavy Bombardment</a>. <a href="/facts/Napier_Mountains/1gPAbhdH">Napier</a> Orogeny in Antarctica, 4,000 ± 200 Ma.</td><td>4031 <a class="footnote-ref" id="fnref:224" href="#fn:224"><sup>224</sup></a></td></tr><tr><td><a href="/facts/Hadean/j7LWS4ah">Hadean</a></td><td colspan="5">Formation of <a href="/facts/Protolith/72uzWogN">protolith</a> of the oldest known rock (<a href="/facts/Acasta_Gneiss/oAcze9EC">Acasta Gneiss</a>) c. 4,031 to 3,580 Ma.<a class="footnote-ref" id="fnref:225" href="#fn:225"><sup>225</sup></a><a class="footnote-ref" id="fnref:226" href="#fn:226"><sup>226</sup></a> Possible first appearance of <a href="/facts/Plate_tectonic/RtRG5lY4">plate tectonics</a>. First hypothetical <a href="/facts/Abiogenesis/BvAmLPQP">life forms</a>. End of the Early Bombardment Phase. Oldest known <a href="/facts/Mineral/LkUFbNmv">mineral</a> (<a href="/facts/Zircon/84APfbLt">Zircon</a>, 4,404 ± 8 Ma).<a class="footnote-ref" id="fnref:227" href="#fn:227"><sup>227</sup></a> Asteroids and comets bring water to Earth, forming the first oceans. Formation of <a href="/facts/Moon/zKHqEMPb">Moon</a> (4,510 Ma), probably from a <a href="/facts/Giant_impact_hypothesis/x2cw2Xxn">giant impact</a>. Formation of Earth (4,543 to 4,540 Ma)</td><td>4567 ± 0.16 <a class="footnote-ref" id="fnref:228" href="#fn:228"><sup>228</sup></a></td></tr></tbody></table> <h2 id="non-earth-based-geologic-time-scales">Non-Earth based geologic time scales</h2> <p class="note">Main articles: <a href="/facts/Lunar_geologic_timescale/A6p18RHw">Lunar geologic timescale</a>, <a href="/facts/Martian_geologic_timescale/P4gYrvYf">Martian geologic timescale</a>, and <a href="/facts/Geology_of_Venus/VsAPkWfv">Geology of Venus</a></p><p>Some other <a href="/facts/Planet/rbPjE6Bx">planets</a> and <a href="/facts/Natural_satellite/AE4KQKbq">satellites</a> in the <a href="/facts/Solar_System/QIcLSazQ">Solar System</a> have sufficiently rigid structures to have preserved records of their own histories, for example, <a href="/facts/Geology_of_Venus/VsAPkWfv">Venus</a>, <a href="/facts/Geology_of_Mars/rt6zWIKx">Mars</a> and the Earth's <a href="/facts/Moon/zKHqEMPb">Moon</a>. Dominantly fluid planets, such as the <a href="/facts/Giant_planet/PjSfFuUF">giant planets</a>, do not comparably preserve their history. Apart from the <a href="/facts/Late_Heavy_Bombardment/PBUlnPJX">Late Heavy Bombardment</a>, 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.<a class="footnote-ref" id="fnref:229" href="#fn:229"><sup>229</sup></a> </p><h3>Lunar (selenological) time scale</h3> <p>The <a href="/facts/Geology_of_the_Moon/vhIu0V7k">geologic history</a> of Earth's Moon has been divided into a time scale based on <a href="/facts/Geomorphology/MDf2I2h5">geomorphological</a> markers, namely <a href="/facts/Impact_crater/nWntooh4">impact cratering</a>, <a href="/facts/Volcanism/0s6p1eFJ">volcanism</a>, and <a href="/facts/Erosion/gaGJXy0W">erosion</a>. 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 (<a href="/facts/Pre-Nectarian/73k61S0s">Pre-Nectarian</a>, <a href="/facts/Nectarian/pJvdQISJ">Nectarian</a>, <a href="/facts/Imbrian/ysrvjxFW">Imbrian</a>, <a href="/facts/Eratosthenian/WmHNLIA1">Eratosthenian</a>, <a href="/facts/Copernican_period/39uxDII5">Copernican</a>), with the Imbrian divided into two series/epochs (Early and Late) were defined in the latest Lunar geologic time scale.<a class="footnote-ref" id="fnref:230" href="#fn:230"><sup>230</sup></a> 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. </p> Millions of years before present <h3>Martian geologic time scale</h3> <p>The <a href="/facts/Geological_history_of_Mars/P4gYrvYf">geological history of Mars</a> 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).<a class="footnote-ref" id="fnref:231" href="#fn:231"><sup>231</sup></a><a class="footnote-ref" id="fnref:232" href="#fn:232"><sup>232</sup></a> </p> Martian time periods (millions of years ago) <p>Epochs: </p> <p>A second time scale based on mineral alteration observed by the OMEGA <a href="/facts/Spectrometer/IqRE8xaQ">spectrometer</a> on board the <a href="/facts/Mars_Express/wM1scUfh">Mars Express</a>. 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).<a class="footnote-ref" id="fnref:233" href="#fn:233"><sup>233</sup></a> </p> <h2 id="see-also">See also</h2> <ul> <li>Geology portal</li></ul> <ul><li><a href="/facts/Age_of_the_Earth/MxNh2Q11">Age of the Earth</a></li> <li><a href="/facts/Cosmic_calendar/NwD7cdEQ">Cosmic calendar</a></li> <li><a href="/facts/Deep_time/0Pxg29TF">Deep time</a></li> <li><a href="/facts/Evolutionary_history_of_life/Ss6eB0EX">Evolutionary history of life</a></li> <li><a href="/facts/Formation_and_evolution_of_the_Solar_System/cgElXHpM">Formation and evolution of the Solar System</a></li> <li><a href="/facts/Geological_history_of_Earth/Jx7ClmF4">Geological history of Earth</a></li> <li><a href="/facts/Geology_of_Mars/rt6zWIKx">Geology of Mars</a></li> <li><a href="/facts/Geon_(geology)/LFU8u0VX">Geon (geology)</a></li> <li><a href="/facts/History_of_Earth/0aEAQF0k">History of Earth</a></li> <li><a href="/facts/History_of_geology/m6xGQNWn">History of geology</a></li> <li><a href="/facts/History_of_paleontology/Ey06mdQD">History of paleontology</a></li> <li><a href="/facts/List_of_fossil_sites/6gYhEPes">List of fossil sites</a></li> <li><a href="/facts/List_of_geochronologic_names/x69zhphS">List of geochronologic names</a></li> <li><a href="/facts/Lunar_geologic_timescale/A6p18RHw">Lunar geologic timescale</a></li> <li><a href="/facts/Martian_geologic_timescale/P4gYrvYf">Martian geologic timescale</a></li> <li><a href="/facts/Natural_history/pSlAvbTX">Natural history</a></li> <li><a href="/facts/New_Zealand_geologic_time_scale/ycr8K7ez">New Zealand geologic time scale</a></li> <li><a href="/facts/Prehistoric_life/Ss6eB0EX">Prehistoric life</a></li> <li><a href="/facts/Timeline_of_the_Big_Bang/ezBKAdjy">Timeline of the Big Bang</a></li> <li><a href="/facts/Timeline_of_evolution/ehf7lh2p">Timeline of evolution</a></li> <li><a href="/facts/Timeline_of_the_geologic_history_of_the_United_States/WKVjIF7t">Timeline of the geologic history of the United States</a></li> <li><a href="/facts/Timeline_of_human_evolution/HKHaJTXx">Timeline of human evolution</a></li> <li><a href="/facts/Timeline_of_natural_history/7htqc31E">Timeline of natural history</a></li> <li><a href="/facts/Timeline_of_paleontology/IeMxbrxB">Timeline of paleontology</a></li></ul> <h2 id="notes">Notes</h2> <h2 id="further-reading">Further reading</h2> <ul><li>Aubry, Marie-Pierre; Van Couvering, John A.; Christie-Blick, Nicholas; Landing, Ed; Pratt, Brian R.; Owen, Donald E.; Ferrusquia-Villafranca, Ismael (2009). "Terminology of geological time: Establishment of a community standard". <i>Stratigraphy</i>. 6 (2): 100–105. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.7916%2FD8DR35JQ">10.7916/D8DR35JQ</a>.</li> <li>Gradstein, F. M.; Ogg, J. G. (2004). <a href="https://web.archive.org/web/20180417173639/http://eesc.columbia.edu/courses/w4937/Readings/Gradstein_Ogg_2004.pdf">"A Geologic Time scale 2004 – Why, How and Where Next!"</a> (PDF). <i>Lethaia</i>. 37 (2): 175–181. <a href="/facts/Bibcode_(identifier)/9HtdQSGB">Bibcode</a>:<a href="https://ui.adsabs.harvard.edu/abs/2004Letha..37..175G">2004Letha..37..175G</a>. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1080%2F00241160410006483">10.1080/00241160410006483</a>. Archived from <a href="https://eesc.columbia.edu/courses/w4937/Readings/Gradstein_Ogg_2004.pdf">the original</a> (PDF) on 17 April 2018. Retrieved 30 November 2018.</li> <li>Gradstein, Felix M.; Ogg, James G.; Smith, Alan G. (2004). <a href="https://books.google.com/books?id=rse4v1P-f9kC"><i>A Geologic Time Scale 2004</i></a>. Cambridge, UK: Cambridge University Press. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-521-78142-8. Retrieved 18 November 2011.</li> <li>Gradstein, Felix M.; Ogg, James G.; Smith, Alan G.; Bleeker, Wouter; Laurens, Lucas, J. (June 2004). <a href="https://doi.org/10.18814%2Fepiiugs%2F2004%2Fv27i2%2F002">"A new Geologic Time Scale, with special reference to Precambrian and Neogene"</a>. <i>Episodes</i>. 27 (2): 83–100. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.18814%2Fepiiugs%2F2004%2Fv27i2%2F002">10.18814/epiiugs/2004/v27i2/002</a>.{{cite journal}}: CS1 maint: multiple names: authors list (link)</li> <li>Ialenti, Vincent (28 September 2014). <a href="https://www.npr.org/sections/13.7/2014/09/28/351692717/embracing-deep-time-thinking">"Embracing 'Deep Time' Thinking"</a>. <i>NPR</i>. NPR Cosmos & Culture.</li> <li>Ialenti, Vincent (21 September 2014). <a href="https://www.npr.org/sections/13.7/2014/09/21/350344129/pondering-deep-time-could-inspire-new-ways-to-view-climate-change">"Pondering 'Deep Time' Could Inspire New Ways To View Climate Change"</a>. <i>NPR</i>. NPR Cosmos & Culture.</li> <li><a href="/facts/Andrew_H._Knoll/hT6xBBlW">Knoll, Andrew H.</a>; Walter, Malcolm R.; Narbonne, Guy M.; Christie-Blick, Nicholas (30 July 2004). <a href="http://www.ldeo.columbia.edu/~ncb/Selected_Articles_all_files/17_Science%20305.621.pdf">"A New Period for the Geologic Time Scale"</a> (PDF). <i><a href="/facts/Science_(journal)/uTyzjkwD">Science</a></i>. 305 (5684): 621–622. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1126%2Fscience.1098803">10.1126/science.1098803</a>. <a href="/facts/PMID_(identifier)/JlHAvMHt">PMID</a> <a href="https://pubmed.ncbi.nlm.nih.gov/15286353">15286353</a>. <a href="/facts/S2CID_(identifier)/ldJsHa2Y">S2CID</a> <a href="https://api.semanticscholar.org/CorpusID:32763298">32763298</a>. <a href="https://web.archive.org/web/20111215034718/http://www.ldeo.columbia.edu/%7Encb/Selected_Articles_all_files/17_Science%20305.621.pdf">Archived</a> (PDF) from the original on 15 December 2011. Retrieved 18 November 2011.</li> <li>Levin, Harold L. (2010). <a href="https://books.google.com/books?id=D0yl7Cqsu78C&pg=PA29">"Time and Geology"</a>. <a href="https://books.google.com/books?id=D0yl7Cqsu78C"><i>The Earth Through Time</i></a>. Hoboken, New Jersey: John Wiley & Sons. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-470-38774-0. Retrieved 18 November 2011.</li> <li>Montenari, Michael (2016). <a href="https://books.google.com/books?id=xzJQDAAAQBAJ"><i>Stratigraphy and Timescales</i></a> (1st ed.). Amsterdam: Academic Press (Elsevier). <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-12-811549-7.</li> <li>Montenari, Michael (2017). <a href="https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/2/suppl/C"><i>Advances in Sequence Stratigraphy</i></a> (1st ed.). Amsterdam: Academic Press (Elsevier). <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-12-813077-3.</li> <li>Montenari, Michael (2018). <a href="https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/3/suppl/C"><i>Cyclostratigraphy and Astrochronology</i></a> (1st ed.). Amsterdam: Academic Press (Elsevier). <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-12-815098-6.</li> <li>Montenari, Michael (2019). <a href="https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/4/suppl/C"><i>Case Studies in Isotope Stratigraphy</i></a> (1st ed.). Amsterdam: Academic Press (Elsevier). <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-12-817552-1.</li> <li>Montenari, Michael (2020). <a href="https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/5/suppl/C"><i>Carbon Isotope Stratigraphy</i></a> (1st ed.). Amsterdam: Academic Press (Elsevier). <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-12-820991-2.</li> <li>Montenari, Michael (2021). <a href="https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/6/suppl/C"><i>Calcareous Nannofossil Biostratigraphy</i></a> (1st ed.). Amsterdam: Academic Press (Elsevier). <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-12-824624-5.</li> <li>Montenari, Michael (2022). <a href="https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/7/suppl/C">Integrated Quaternary Stratigraphy</a> (1st ed.). Amsterdam: Academic Press (Elsevier). ISBN 978-0-323-98913-8.</li> <li>Montenari, Michael (2023). <a href="https://www.sciencedirect.com/bookseries/stratigraphy-and-timescales/vol/8/suppl/C">Stratigraphy of Geo- and Biodynamic Processes</a> (1st ed.). Amsterdam: Academic Press (Elsevier). ISBN 978-0-323-99242-8.</li> <li>Nichols, Gary (2013). <i><a href="https://books.google.com/books?id=Gcgp5oLFrZMC">Sedimentology and Stratigraphy</a></i> (2nd ed.). Hoboken: Wiley-Blackwell. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-1-4051-3592-4</li> <li>Williams, Aiden (2019). <i><a href="https://books.google.com/books?id=etVhxQEACAAJ">Sedimentology and Stratigraphy</a></i> (1st ed.). Forest Hills, NY: Callisto Reference. <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-1-64116-075-9</li></ul> <h2 id="external-links">External links</h2> Wikimedia Commons has media related to Geologic time scale. The Wikibook <i>Historical Geology</i> has a page on the topic of: <i>Geological column</i> <ul><li>The current version of the International Chronostratigraphic Chart can be found at <a href="https://stratigraphy.org/chart">stratigraphy.org/chart</a></li> <li>Interactive version of the International Chronostratigraphic Chart is found at <a href="https://stratigraphy.org/timescale">stratigraphy.org/timescale</a></li> <li>A list of current Global Boundary Stratotype and Section Points is found at <a href="https://stratigraphy.org/gssps/">stratigraphy.org/gssps</a></li> <li><a href="https://web.archive.org/web/20050418090602/http://rst.gsfc.nasa.gov/Sect2/Sect2_1b.html">NASA: Geologic Time</a> (archived 18 April 2005)</li> <li><a href="https://web.archive.org/web/20190120115100/https://www.geosociety.org/GSA/Education_Careers/Geologic_Time_Scale/GSA/timescale/home.aspx">GSA: Geologic Time Scale</a> (archived 20 January 2019)</li> <li><a href="http://www.bgs.ac.uk/discoveringGeology/time/timechart/home.html">British Geological Survey: Geological Timechart</a></li> <li><a href="https://web.archive.org/web/20040623025505/http://www.stratigraphy.org/geowhen/">GeoWhen Database</a> (archived 23 June 2004)</li> <li><a href="https://web.archive.org/web/20051111150720/http://www.nmnh.si.edu/paleo/geotime/index.htm">National Museum of Natural History – Geologic Time</a> (archived 11 November 2005)</li> <li><a href="https://www.seegrid.csiro.au/twiki/bin/view/CGIModel/GeologicTime">SeeGrid: Geological Time Systems</a>. <a href="https://web.archive.org/web/20080723195950/https://www.seegrid.csiro.au/twiki/bin/view/CGIModel/GeologicTime">Archived</a> 23 July 2008 at the <a href="/facts/Wayback_Machine/nmQ3a6JC">Wayback Machine</a>. Information model for the geologic time scale.</li> <li><a href="http://exploringtime.org/?page=segments">Exploring Time</a> from Planck Time to the lifespan of the universe</li> <li><a href="https://web.archive.org/web/20120425232455/http://www.episodes.co.in/www/backissues/272/Time%20Scale.pdf">Episodes</a>, Gradstein, Felix M. et al. (2004) <i>A new Geologic Time Scale, with special reference to Precambrian and Neogene</i>, Episodes, Vol. 27, no. 2 June 2004 (pdf)</li> <li>Lane, Alfred C, and Marble, John Putman 1937. <a href="https://books.google.com/books?id=ckIrAAAAYAAJ">Report of the Committee on the measurement of geologic time</a></li> <li><a href="https://web.archive.org/web/20110714173934/http://www.newsciencelessons.com/geology_lesson_plans.html">Lessons for Children on Geologic Time</a> (archived 14 July 2011)</li> <li><a href="http://deeptime.info">Deep Time – A History of the Earth : Interactive Infographic</a></li> <li><a href="https://geology.buzz/threads/geologic-time-scale.36/">Geology Buzz: Geologic Time Scale</a>. <a href="https://web.archive.org/web/20210812084221/https://geology.buzz/threads/geologic-time-scale.36/">Archived</a> 12 August 2021 at the <a href="/facts/Wayback_Machine/nmQ3a6JC">Wayback Machine</a>.</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"Statues & Guidelines". International Commission on Stratigraphy. Retrieved 5 April 2022. <a href="https://stratigraphy.org/statutes" target="_blank">https://stratigraphy.org/statutes</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Cohen, K.M.; Finney, S.C.; Gibbard, P.L.; Fan, J.-X. (1 September 2013). "The ICS International Chronostratigraphic Chart". Episodes. 36 (3) (updated ed.): 199–204. doi:10.18814/epiiugs/2013/v36i3/002. ISSN 0705-3797. S2CID 51819600. <a href="https://doi.org/10.18814%2Fepiiugs%2F2013%2Fv36i3%2F002" target="_blank">https://doi.org/10.18814%2Fepiiugs%2F2013%2Fv36i3%2F002</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Cohen, K.M.; Finney, S.C.; Gibbard, P.L.; Fan, J.-X. (1 September 2013). "The ICS International Chronostratigraphic Chart". Episodes. 36 (3) (updated ed.): 199–204. doi:10.18814/epiiugs/2013/v36i3/002. ISSN 0705-3797. S2CID 51819600. <a href="https://doi.org/10.18814%2Fepiiugs%2F2013%2Fv36i3%2F002" target="_blank">https://doi.org/10.18814%2Fepiiugs%2F2013%2Fv36i3%2F002</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Dalrymple, G. Brent (2001). "The age of the Earth in the twentieth century: a problem (mostly) solved". Special Publications, Geological Society of London. 190 (1): 205–221. Bibcode:2001GSLSP.190..205D. doi:10.1144/GSL.SP.2001.190.01.14. S2CID 130092094. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Shields, Graham A.; Strachan, Robin A.; Porter, Susannah M.; Halverson, Galen P.; Macdonald, Francis A.; Plumb, Kenneth A.; de Alvarenga, Carlos J.; Banerjee, Dhiraj M.; Bekker, Andrey; Bleeker, Wouter; Brasier, Alexander (2022). "A template for an improved rock-based subdivision of the pre-Cryogenian timescale". Journal of the Geological Society. 179 (1): jgs2020–222. Bibcode:2022JGSoc.179..222S. doi:10.1144/jgs2020-222. ISSN 0016-7649. S2CID 236285974. <a href="https://doi.org/10.1144%2Fjgs2020-222" target="_blank">https://doi.org/10.1144%2Fjgs2020-222</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Van Kranendonk, Martin J.; Altermann, Wladyslaw; Beard, Brian L.; Hoffman, Paul F.; Johnson, Clark M.; Kasting, James F.; Melezhik, Victor A.; Nutman, Allen P. (2012), "A Chronostratigraphic Division of the Precambrian", The Geologic Time Scale, Elsevier, pp. 299–392, doi:10.1016/b978-0-444-59425-9.00016-0, ISBN 978-0-444-59425-9, retrieved 5 April 2022 <a href="978-0-444-59425-9" target="_blank">978-0-444-59425-9</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Van Kranendonk, Martin J.; Altermann, Wladyslaw; Beard, Brian L.; Hoffman, Paul F.; Johnson, Clark M.; Kasting, James F.; Melezhik, Victor A.; Nutman, Allen P. (2012), "A Chronostratigraphic Division of the Precambrian", The Geologic Time Scale, Elsevier, pp. 299–392, doi:10.1016/b978-0-444-59425-9.00016-0, ISBN 978-0-444-59425-9, retrieved 5 April 2022 <a href="978-0-444-59425-9" target="_blank">978-0-444-59425-9</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>"International Commission on Stratigraphy - Stratigraphic Guide - Chapter 9. Chronostratigraphic Units". stratigraphy.org. Retrieved 16 April 2024. <a href="https://stratigraphy.org/guide/chron" target="_blank">https://stratigraphy.org/guide/chron</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Boggs, Sam (2011). Principles of sedimentology and stratigraphy (5th ed.). Boston, Munich: Prentice Hall. ISBN 978-0-321-74576-7. <a href="978-0-321-74576-7" target="_blank">978-0-321-74576-7</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Steno, Nicolaus (1669). Nicolai Stenonis de solido intra solidvm natvraliter contento dissertationis prodromvs ad serenissimvm Ferdinandvm II ... (in Latin). W. Junk. <a href="https://books.google.com/books?id=xz28AAAAIAAJ" target="_blank">https://books.google.com/books?id=xz28AAAAIAAJ</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Hutton, James (1795). Theory of the Earth. Vol. 1. Edinburgh. <a href="https://www.gutenberg.org/ebooks/12861" target="_blank">https://www.gutenberg.org/ebooks/12861</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Lyell, Sir Charles (1832). Principles of Geology: Being an Attempt to Explain the Former Changes of the Earth's Surface, by Reference to Causes Now in Operation. Vol. 1. London: John Murray. <a href="https://books.google.com/books?id=mmIOAAAAQAAJ" target="_blank">https://books.google.com/books?id=mmIOAAAAQAAJ</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Boggs, Sam (2011). Principles of sedimentology and stratigraphy (5th ed.). Boston, Munich: Prentice Hall. ISBN 978-0-321-74576-7. <a href="978-0-321-74576-7" target="_blank">978-0-321-74576-7</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Steno, Nicolaus (1669). Nicolai Stenonis de solido intra solidvm natvraliter contento dissertationis prodromvs ad serenissimvm Ferdinandvm II ... (in Latin). W. Junk. <a href="https://books.google.com/books?id=xz28AAAAIAAJ" target="_blank">https://books.google.com/books?id=xz28AAAAIAAJ</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Lyell, Sir Charles (1832). Principles of Geology: Being an Attempt to Explain the Former Changes of the Earth's Surface, by Reference to Causes Now in Operation. Vol. 1. London: John Murray. <a href="https://books.google.com/books?id=mmIOAAAAQAAJ" target="_blank">https://books.google.com/books?id=mmIOAAAAQAAJ</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>Boggs, Sam (2011). Principles of sedimentology and stratigraphy (5th ed.). Boston, Munich: Prentice Hall. ISBN 978-0-321-74576-7. <a href="978-0-321-74576-7" target="_blank">978-0-321-74576-7</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>Boggs, Sam (2011). Principles of sedimentology and stratigraphy (5th ed.). Boston, Munich: Prentice Hall. ISBN 978-0-321-74576-7. <a href="978-0-321-74576-7" target="_blank">978-0-321-74576-7</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>Mehta, A; Barker, G C (1 April 1994). "The dynamics of sand". Reports on Progress in Physics. 57 (4): 383–416. doi:10.1088/0034-4885/57/4/002. ISSN 0034-4885. <a href="https://iopscience.iop.org/article/10.1088/0034-4885/57/4/002" target="_blank">https://iopscience.iop.org/article/10.1088/0034-4885/57/4/002</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>Steno, Nicolaus (1669). Nicolai Stenonis de solido intra solidvm natvraliter contento dissertationis prodromvs ad serenissimvm Ferdinandvm II ... (in Latin). W. Junk. <a href="https://books.google.com/books?id=xz28AAAAIAAJ" target="_blank">https://books.google.com/books?id=xz28AAAAIAAJ</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>Steno, Nicolaus (1669). Nicolai Stenonis de solido intra solidvm natvraliter contento dissertationis prodromvs ad serenissimvm Ferdinandvm II ... (in Latin). W. Junk. <a href="https://books.google.com/books?id=xz28AAAAIAAJ" target="_blank">https://books.google.com/books?id=xz28AAAAIAAJ</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> <li id="fn:21"><p>Hutton, James (1795). Theory of the Earth. Vol. 1. Edinburgh. <a href="https://www.gutenberg.org/ebooks/12861" target="_blank">https://www.gutenberg.org/ebooks/12861</a> <a href="#fnref:21" class="footnote-back-ref">↩</a></p></li> <li id="fn:22"><p>Lyell, Sir Charles (1832). Principles of Geology: Being an Attempt to Explain the Former Changes of the Earth's Surface, by Reference to Causes Now in Operation. Vol. 1. London: John Murray. <a href="https://books.google.com/books?id=mmIOAAAAQAAJ" target="_blank">https://books.google.com/books?id=mmIOAAAAQAAJ</a> <a href="#fnref:22" class="footnote-back-ref">↩</a></p></li> <li id="fn:23"><p>Boggs, Sam (2011). Principles of sedimentology and stratigraphy (5th ed.). Boston, Munich: Prentice Hall. ISBN 978-0-321-74576-7. <a href="978-0-321-74576-7" target="_blank">978-0-321-74576-7</a> <a href="#fnref:23" class="footnote-back-ref">↩</a></p></li> <li id="fn:24"><p>Lyell, Sir Charles (1832). Principles of Geology: Being an Attempt to Explain the Former Changes of the Earth's Surface, by Reference to Causes Now in Operation. Vol. 1. London: John Murray. <a href="https://books.google.com/books?id=mmIOAAAAQAAJ" target="_blank">https://books.google.com/books?id=mmIOAAAAQAAJ</a> <a href="#fnref:24" class="footnote-back-ref">↩</a></p></li> <li id="fn:25"><p>Boggs, Sam (2011). Principles of sedimentology and stratigraphy (5th ed.). Boston, Munich: Prentice Hall. ISBN 978-0-321-74576-7. <a href="978-0-321-74576-7" target="_blank">978-0-321-74576-7</a> <a href="#fnref:25" class="footnote-back-ref">↩</a></p></li> <li id="fn:26"><p>Boggs, Sam (2011). Principles of sedimentology and stratigraphy (5th ed.). Boston, Munich: Prentice Hall. ISBN 978-0-321-74576-7. <a href="978-0-321-74576-7" target="_blank">978-0-321-74576-7</a> <a href="#fnref:26" class="footnote-back-ref">↩</a></p></li> <li id="fn:27"><p>Smith, William (1 June 1816). Strata identified by organized fossils, containing prints on colored paper of the most characteristic specimens in each stratum. London: W. Arding. doi:10.5962/bhl.title.106808. <a href="http://www.biodiversitylibrary.org/bibliography/106808" target="_blank">http://www.biodiversitylibrary.org/bibliography/106808</a> <a href="#fnref:27" class="footnote-back-ref">↩</a></p></li> <li id="fn:28"><p>Boggs, Sam (2011). Principles of sedimentology and stratigraphy (5th ed.). Boston, Munich: Prentice Hall. ISBN 978-0-321-74576-7. <a href="978-0-321-74576-7" target="_blank">978-0-321-74576-7</a> <a href="#fnref:28" class="footnote-back-ref">↩</a></p></li> <li id="fn:29"><p>Michael Allaby (2020). A dictionary of geology and earth sciences (Fifth ed.). Oxford. ISBN 978-0-19-187490-1. OCLC 1137380460.{{cite book}}: CS1 maint: location missing publisher (link) <a href="978-0-19-187490-1" target="_blank">978-0-19-187490-1</a> <a href="#fnref:29" class="footnote-back-ref">↩</a></p></li> <li id="fn:30"><p>Cohen, K.M.; Finney, S.C.; Gibbard, P.L.; Fan, J.-X. (1 September 2013). "The ICS International Chronostratigraphic Chart". Episodes. 36 (3) (updated ed.): 199–204. doi:10.18814/epiiugs/2013/v36i3/002. ISSN 0705-3797. S2CID 51819600. <a href="https://doi.org/10.18814%2Fepiiugs%2F2013%2Fv36i3%2F002" target="_blank">https://doi.org/10.18814%2Fepiiugs%2F2013%2Fv36i3%2F002</a> <a href="#fnref:30" class="footnote-back-ref">↩</a></p></li> <li id="fn:31"><p>"Chapter 9. Chronostratigraphic Units". stratigraphy.org. International Commission on Stratigraphy. Retrieved 2 April 2022. <a href="https://stratigraphy.org/guide/chron" target="_blank">https://stratigraphy.org/guide/chron</a> <a href="#fnref:31" class="footnote-back-ref">↩</a></p></li> <li id="fn:32"><p>Michael Allaby (2020). A dictionary of geology and earth sciences (Fifth ed.). Oxford. ISBN 978-0-19-187490-1. OCLC 1137380460.{{cite book}}: CS1 maint: location missing publisher (link) <a href="978-0-19-187490-1" target="_blank">978-0-19-187490-1</a> <a href="#fnref:32" class="footnote-back-ref">↩</a></p></li> <li id="fn:33"><p>Cohen, K.M.; Finney, S.C.; Gibbard, P.L.; Fan, J.-X. (1 September 2013). "The ICS International Chronostratigraphic Chart". Episodes. 36 (3) (updated ed.): 199–204. doi:10.18814/epiiugs/2013/v36i3/002. ISSN 0705-3797. S2CID 51819600. <a href="https://doi.org/10.18814%2Fepiiugs%2F2013%2Fv36i3%2F002" target="_blank">https://doi.org/10.18814%2Fepiiugs%2F2013%2Fv36i3%2F002</a> <a href="#fnref:33" class="footnote-back-ref">↩</a></p></li> <li id="fn:34"><p>"Chapter 9. Chronostratigraphic Units". stratigraphy.org. International Commission on Stratigraphy. Retrieved 2 April 2022. <a href="https://stratigraphy.org/guide/chron" target="_blank">https://stratigraphy.org/guide/chron</a> <a href="#fnref:34" class="footnote-back-ref">↩</a></p></li> <li id="fn:35"><p>Michael Allaby (2020). A dictionary of geology and earth sciences (Fifth ed.). Oxford. ISBN 978-0-19-187490-1. OCLC 1137380460.{{cite book}}: CS1 maint: location missing publisher (link) <a href="978-0-19-187490-1" target="_blank">978-0-19-187490-1</a> <a href="#fnref:35" class="footnote-back-ref">↩</a></p></li> <li id="fn:36"><p>Cohen, K.M.; Finney, S.C.; Gibbard, P.L.; Fan, J.-X. (1 September 2013). "The ICS International Chronostratigraphic Chart". Episodes. 36 (3) (updated ed.): 199–204. doi:10.18814/epiiugs/2013/v36i3/002. ISSN 0705-3797. S2CID 51819600. <a href="https://doi.org/10.18814%2Fepiiugs%2F2013%2Fv36i3%2F002" target="_blank">https://doi.org/10.18814%2Fepiiugs%2F2013%2Fv36i3%2F002</a> <a href="#fnref:36" class="footnote-back-ref">↩</a></p></li> <li id="fn:37"><p>"Chapter 9. Chronostratigraphic Units". stratigraphy.org. International Commission on Stratigraphy. Retrieved 2 April 2022. <a href="https://stratigraphy.org/guide/chron" target="_blank">https://stratigraphy.org/guide/chron</a> <a href="#fnref:37" class="footnote-back-ref">↩</a></p></li> <li id="fn:38"><p>"Chapter 9. Chronostratigraphic Units". stratigraphy.org. International Commission on Stratigraphy. Retrieved 2 April 2022. <a href="https://stratigraphy.org/guide/chron" target="_blank">https://stratigraphy.org/guide/chron</a> <a href="#fnref:38" class="footnote-back-ref">↩</a></p></li> <li id="fn:39"><p>Michael Allaby (2020). A dictionary of geology and earth sciences (Fifth ed.). Oxford. ISBN 978-0-19-187490-1. OCLC 1137380460.{{cite book}}: CS1 maint: location missing publisher (link) <a href="978-0-19-187490-1" target="_blank">978-0-19-187490-1</a> <a href="#fnref:39" class="footnote-back-ref">↩</a></p></li> <li id="fn:40"><p>Cohen, K.M.; Finney, S.C.; Gibbard, P.L.; Fan, J.-X. (1 September 2013). "The ICS International Chronostratigraphic Chart". Episodes. 36 (3) (updated ed.): 199–204. doi:10.18814/epiiugs/2013/v36i3/002. ISSN 0705-3797. S2CID 51819600. <a href="https://doi.org/10.18814%2Fepiiugs%2F2013%2Fv36i3%2F002" target="_blank">https://doi.org/10.18814%2Fepiiugs%2F2013%2Fv36i3%2F002</a> <a href="#fnref:40" class="footnote-back-ref">↩</a></p></li> <li id="fn:41"><p>Aubry, Marie-Pierre; Piller, Werner E.; Gibbard, Philip L.; Harper, David A. T.; Finney, Stanley C. (1 March 2022). "Ratification of subseries/subepochs as formal rank/units in international chronostratigraphy". Episodes. 45 (1): 97–99. doi:10.18814/epiiugs/2021/021016. ISSN 0705-3797. S2CID 240772165. <a href="https://doi.org/10.18814%2Fepiiugs%2F2021%2F021016" target="_blank">https://doi.org/10.18814%2Fepiiugs%2F2021%2F021016</a> <a href="#fnref:41" class="footnote-back-ref">↩</a></p></li> <li id="fn:42"><p>"Chapter 9. Chronostratigraphic Units". stratigraphy.org. International Commission on Stratigraphy. Retrieved 2 April 2022. <a href="https://stratigraphy.org/guide/chron" target="_blank">https://stratigraphy.org/guide/chron</a> <a href="#fnref:42" class="footnote-back-ref">↩</a></p></li> <li id="fn:43"><p>Michael Allaby (2020). A dictionary of geology and earth sciences (Fifth ed.). Oxford. ISBN 978-0-19-187490-1. OCLC 1137380460.{{cite book}}: CS1 maint: location missing publisher (link) <a href="978-0-19-187490-1" target="_blank">978-0-19-187490-1</a> <a href="#fnref:43" class="footnote-back-ref">↩</a></p></li> <li id="fn:44"><p>Cohen, K.M.; Finney, S.C.; Gibbard, P.L.; Fan, J.-X. (1 September 2013). "The ICS International Chronostratigraphic Chart". Episodes. 36 (3) (updated ed.): 199–204. doi:10.18814/epiiugs/2013/v36i3/002. ISSN 0705-3797. S2CID 51819600. <a href="https://doi.org/10.18814%2Fepiiugs%2F2013%2Fv36i3%2F002" target="_blank">https://doi.org/10.18814%2Fepiiugs%2F2013%2Fv36i3%2F002</a> <a href="#fnref:44" class="footnote-back-ref">↩</a></p></li> <li id="fn:45"><p>"Chapter 9. Chronostratigraphic Units". stratigraphy.org. International Commission on Stratigraphy. Retrieved 2 April 2022. <a href="https://stratigraphy.org/guide/chron" target="_blank">https://stratigraphy.org/guide/chron</a> <a href="#fnref:45" class="footnote-back-ref">↩</a></p></li> <li id="fn:46"><p>Time spans of geologic time units vary broadly, and there is no numeric limitation on the time span they can represent. They are limited by the time span of the higher rank unit they belong to, and to the chronostratigraphic boundaries they are defined by. <a href="#fnref:46" class="footnote-back-ref">↩</a></p></li> <li id="fn:47"><p>"Chapter 9. Chronostratigraphic Units". stratigraphy.org. International Commission on Stratigraphy. Retrieved 2 April 2022. <a href="https://stratigraphy.org/guide/chron" target="_blank">https://stratigraphy.org/guide/chron</a> <a href="#fnref:47" class="footnote-back-ref">↩</a></p></li> <li id="fn:48"><p>"Chapter 9. Chronostratigraphic Units". stratigraphy.org. International Commission on Stratigraphy. Retrieved 2 April 2022. <a href="https://stratigraphy.org/guide/chron" target="_blank">https://stratigraphy.org/guide/chron</a> <a href="#fnref:48" class="footnote-back-ref">↩</a></p></li> <li id="fn:49"><p>"Chapter 3. Definitions and Procedures". stratigraphy.org. International Commission on Stratigraphy. Retrieved 2 April 2022. <a href="https://stratigraphy.org/guide/defs" target="_blank">https://stratigraphy.org/guide/defs</a> <a href="#fnref:49" class="footnote-back-ref">↩</a></p></li> <li id="fn:50"><p>"Chapter 9. Chronostratigraphic Units". stratigraphy.org. International Commission on Stratigraphy. Retrieved 2 April 2022. <a href="https://stratigraphy.org/guide/chron" target="_blank">https://stratigraphy.org/guide/chron</a> <a href="#fnref:50" class="footnote-back-ref">↩</a></p></li> <li id="fn:51"><p>"Chapter 3. Definitions and Procedures". stratigraphy.org. International Commission on Stratigraphy. Retrieved 2 April 2022. <a href="https://stratigraphy.org/guide/defs" target="_blank">https://stratigraphy.org/guide/defs</a> <a href="#fnref:51" class="footnote-back-ref">↩</a></p></li> <li id="fn:52"><p>"Global Boundary Stratotype Section and Points". stratigraphy.org. International Commission on Stratigraphy. Retrieved 2 April 2022. <a href="https://stratigraphy.org/gssps/" target="_blank">https://stratigraphy.org/gssps/</a> <a href="#fnref:52" class="footnote-back-ref">↩</a></p></li> <li id="fn:53"><p>Knoll, Andrew; Walter, Malcolm; Narbonne, Guy; Christie-Blick, Nicholas (2006). "The Ediacaran Period: a new addition to the geologic time scale". Lethaia. 39 (1): 13–30. Bibcode:2006Letha..39...13K. doi:10.1080/00241160500409223. <a href="http://doi.wiley.com/10.1080/00241160500409223" target="_blank">http://doi.wiley.com/10.1080/00241160500409223</a> <a href="#fnref:53" class="footnote-back-ref">↩</a></p></li> <li id="fn:54"><p>Remane, Jürgen; Bassett, Michael G; Cowie, John W; Gohrbandt, Klaus H; Lane, H Richard; Michelsen, Olaf; Naiwen, Wang; the cooperation of members of ICS (1 September 1996). "Revised guidelines for the establishment of global chronostratigraphic standards by the International Commission on Stratigraphy (ICS)". Episodes. 19 (3): 77–81. doi:10.18814/epiiugs/1996/v19i3/007. ISSN 0705-3797. <a href="https://doi.org/10.18814%2Fepiiugs%2F1996%2Fv19i3%2F007" target="_blank">https://doi.org/10.18814%2Fepiiugs%2F1996%2Fv19i3%2F007</a> <a href="#fnref:54" class="footnote-back-ref">↩</a></p></li> <li id="fn:55"><p>"Chapter 9. Chronostratigraphic Units". stratigraphy.org. International Commission on Stratigraphy. Retrieved 2 April 2022. <a href="https://stratigraphy.org/guide/chron" target="_blank">https://stratigraphy.org/guide/chron</a> <a href="#fnref:55" class="footnote-back-ref">↩</a></p></li> <li id="fn:56"><p>"Chapter 9. Chronostratigraphic Units". stratigraphy.org. International Commission on Stratigraphy. Retrieved 2 April 2022. <a href="https://stratigraphy.org/guide/chron" target="_blank">https://stratigraphy.org/guide/chron</a> <a href="#fnref:56" class="footnote-back-ref">↩</a></p></li> <li id="fn:57"><p>Shields, Graham A.; Strachan, Robin A.; Porter, Susannah M.; Halverson, Galen P.; Macdonald, Francis A.; Plumb, Kenneth A.; de Alvarenga, Carlos J.; Banerjee, Dhiraj M.; Bekker, Andrey; Bleeker, Wouter; Brasier, Alexander (2022). "A template for an improved rock-based subdivision of the pre-Cryogenian timescale". Journal of the Geological Society. 179 (1): jgs2020–222. Bibcode:2022JGSoc.179..222S. doi:10.1144/jgs2020-222. ISSN 0016-7649. S2CID 236285974. <a href="https://doi.org/10.1144%2Fjgs2020-222" target="_blank">https://doi.org/10.1144%2Fjgs2020-222</a> <a href="#fnref:57" class="footnote-back-ref">↩</a></p></li> <li id="fn:58"><p>Precambrian or pre-Cambrian is an informal geological term for time before the Cambrian period <a href="#fnref:58" class="footnote-back-ref">↩</a></p></li> <li id="fn:59"><p>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.[20][21] <a href="#fnref:59" class="footnote-back-ref">↩</a></p></li> <li id="fn:60"><p>Desnoyers, J. (1829). "Observations sur un ensemble de dépôts marins plus récents que les terrains tertiaires du bassin de la Seine, et constituant une formation géologique distincte; précédées d'un aperçu de la nonsimultanéité des bassins tertiares" [Observations on a set of marine deposits [that are] more recent than the tertiary terrains of the Seine basin and [that] constitute a distinct geological formation; preceded by an outline of the non-simultaneity of tertiary basins]. Annales des Sciences Naturelles (in French). 16: 171–214, 402–491. From p. 193: "Ce que je désirerais ... dont il faut également les distinguer." (What I would desire to prove above all is that the series of tertiary deposits continued – and even began in the more recent basins – for a long time, perhaps after that of the Seine had been completely filled, and that these later formations – Quaternary (1), so to say – should not retain the name of alluvial deposits any more than the true and ancient tertiary deposits, from which they must also be distinguished.) However, on the very same page, Desnoyers abandoned the use of the term "Quaternary" because the distinction between Quaternary and Tertiary deposits wasn't clear. From p. 193: "La crainte de voir mal comprise ... que ceux du bassin de la Seine." (The fear of seeing my opinion in this regard be misunderstood or exaggerated, has made me abandon the word "quaternary", which at first I had wanted to apply to all deposits more recent than those of the Seine basin.) <a href="https://www.biodiversitylibrary.org/item/29350#page/177/mode/1up" target="_blank">https://www.biodiversitylibrary.org/item/29350#page/177/mode/1up</a> <a href="#fnref:60" class="footnote-back-ref">↩</a></p></li> <li id="fn:61"><p>d'Halloy, d'O., J.-J. (1822). "Observations sur un essai de carte géologique de la France, des Pays-Bas, et des contrées voisines" [Observations on a trial geological map of France, the Low Countries, and neighboring countries]. Annales des Mines. 7: 353–376.{{cite journal}}: CS1 maint: multiple names: authors list (link) From page 373: "La troisième, qui correspond à ce qu'on a déja appelé formation de la craie, sera désigné par le nom de terrain crétacé." (The third, which corresponds to what was already called the "chalk formation", will be designated by the name "chalky terrain".) <a href="https://books.google.com/books?id=c-ocAQAAIAAJ&pg=PA353" target="_blank">https://books.google.com/books?id=c-ocAQAAIAAJ&pg=PA353</a> <a href="#fnref:61" class="footnote-back-ref">↩</a></p></li> <li id="fn:62"><p>Humboldt, Alexander von (1799). Ueber die unterirdischen Gasarten und die Mittel ihren Nachtheil zu vermindern: ein Beytrag zur Physik der praktischen Bergbaukunde (in German). Vieweg. <a href="https://books.google.com/books?id=oZ5PAAAAcAAJ" target="_blank">https://books.google.com/books?id=oZ5PAAAAcAAJ</a> <a href="#fnref:62" class="footnote-back-ref">↩</a></p></li> <li id="fn:63"><p>Brongniart, Alexandre (1770-1847) Auteur du texte (1829). Tableau des terrains qui composent l'écorce du globe ou Essai sur la structure de la partie connue de la terre . Par Alexandre Brongniart,... (in French).{{cite book}}: CS1 maint: numeric names: authors list (link) <a href="https://gallica.bnf.fr/ark:/12148/bpt6k255061" target="_blank">https://gallica.bnf.fr/ark:/12148/bpt6k255061</a> <a href="#fnref:63" class="footnote-back-ref">↩</a></p></li> <li id="fn:64"><p>Ogg, J.G.; Hinnov, L.A.; Huang, C. (2012), "Jurassic", The Geologic Time Scale, Elsevier, pp. 731–791, doi:10.1016/b978-0-444-59425-9.00026-3, ISBN 978-0-444-59425-9, retrieved 1 May 2022 <a href="978-0-444-59425-9" target="_blank">978-0-444-59425-9</a> <a href="#fnref:64" class="footnote-back-ref">↩</a></p></li> <li id="fn:65"><p>Murchison; Murchison, Sir Roderick Impey; Verneuil; Keyserling, Graf Alexander (1842). On the Geological Structure of the Central and Southern Regions of Russia in Europe, and of the Ural Mountains. Print. by R. and J.E. 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The geologic time scale 2012. Volume 2 (1st ed.). Amsterdam: Elsevier. ISBN 978-0-444-59448-8. OCLC 808340848. <a href="978-0-444-59448-8" target="_blank">978-0-444-59448-8</a> <a href="#fnref:161" class="footnote-back-ref">↩</a></p></li> <li id="fn:162"><p>Goldblatt, C.; Zahnle, K. J.; Sleep, N. H.; Nisbet, E. G. (2010). "The Eons of Chaos and Hades". Solid Earth. 1 (1): 1–3. Bibcode:2010SolE....1....1G. doi:10.5194/se-1-1-2010. <a href="https://doi.org/10.5194%2Fse-1-1-2010" target="_blank">https://doi.org/10.5194%2Fse-1-1-2010</a> <a href="#fnref:162" class="footnote-back-ref">↩</a></p></li> <li id="fn:163"><p>F. M. Gradstein (2012). The geologic time scale 2012. Volume 2 (1st ed.). Amsterdam: Elsevier. ISBN 978-0-444-59448-8. OCLC 808340848. <a href="978-0-444-59448-8" target="_blank">978-0-444-59448-8</a> <a href="#fnref:163" class="footnote-back-ref">↩</a></p></li> <li id="fn:164"><p>F. M. Gradstein (2012). The geologic time scale 2012. Volume 2 (1st ed.). Amsterdam: Elsevier. 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OCLC 808340848. <a href="978-0-444-59448-8" target="_blank">978-0-444-59448-8</a> <a href="#fnref:174" class="footnote-back-ref">↩</a></p></li> <li id="fn:175"><p>Precambrian or pre-Cambrian is an informal geological term for time before the Cambrian period <a href="#fnref:175" class="footnote-back-ref">↩</a></p></li> <li id="fn:176"><p>Shields, Graham A.; Strachan, Robin A.; Porter, Susannah M.; Halverson, Galen P.; Macdonald, Francis A.; Plumb, Kenneth A.; de Alvarenga, Carlos J.; Banerjee, Dhiraj M.; Bekker, Andrey; Bleeker, Wouter; Brasier, Alexander (2022). "A template for an improved rock-based subdivision of the pre-Cryogenian timescale". Journal of the Geological Society. 179 (1): jgs2020–222. Bibcode:2022JGSoc.179..222S. doi:10.1144/jgs2020-222. ISSN 0016-7649. 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An * indicates boundaries where a Global Boundary Stratotype Section and Point has been internationally agreed. <a href="/wiki/International_Commission_on_Stratigraphy" target="_blank">/wiki/International_Commission_on_Stratigraphy</a> <a href="#fnref:185" class="footnote-back-ref">↩</a></p></li> <li id="fn:186"><p>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.[20][21] <a href="#fnref:186" class="footnote-back-ref">↩</a></p></li> <li id="fn:187"><p>Hoag, Colin; Svenning, Jens-Christian (17 October 2017). "African Environmental Change from the Pleistocene to the Anthropocene". Annual Review of Environment and Resources. 42 (1): 27–54. doi:10.1146/annurev-environ-102016-060653. ISSN 1543-5938. Archived from the original on 1 May 2022. Retrieved 5 June 2022. <a href="https://web.archive.org/web/20220501144059/https://www.annualreviews.org/doi/10.1146/annurev-environ-102016-060653" target="_blank">https://web.archive.org/web/20220501144059/https://www.annualreviews.org/doi/10.1146/annurev-environ-102016-060653</a> <a href="#fnref:187" class="footnote-back-ref">↩</a></p></li> <li id="fn:188"><p>Bartoli, G; Sarnthein, M; Weinelt, M; Erlenkeuser, H; Garbe-Schönberg, D; Lea, D.W (2005). "Final closure of Panama and the onset of northern hemisphere glaciation". Earth and Planetary Science Letters. 237 (1–2): 33–44. Bibcode:2005E&PSL.237...33B. doi:10.1016/j.epsl.2005.06.020. <a href="https://doi.org/10.1016%2Fj.epsl.2005.06.020" target="_blank">https://doi.org/10.1016%2Fj.epsl.2005.06.020</a> <a href="#fnref:188" class="footnote-back-ref">↩</a></p></li> <li id="fn:189"><p>Tyson, Peter (October 2009). "NOVA, Aliens from Earth: Who's who in human evolution". PBS. Retrieved 8 October 2009. <a href="https://www.pbs.org/wgbh/nova/hobbit/tree-nf.html" target="_blank">https://www.pbs.org/wgbh/nova/hobbit/tree-nf.html</a> <a href="#fnref:189" class="footnote-back-ref">↩</a></p></li> <li id="fn:190"><p>Tyson, Peter (October 2009). "NOVA, Aliens from Earth: Who's who in human evolution". PBS. Retrieved 8 October 2009. <a href="https://www.pbs.org/wgbh/nova/hobbit/tree-nf.html" target="_blank">https://www.pbs.org/wgbh/nova/hobbit/tree-nf.html</a> <a href="#fnref:190" class="footnote-back-ref">↩</a></p></li> <li id="fn:191"><p>Gannon, Colin (26 April 2013). "Understanding the Middle Miocene Climatic Optimum: Evaluation of Deuterium Values (δD) Related to Precipitation and Temperature". Honors Projects in Science and Technology. <a href="https://digitalcommons.bryant.edu/honors_science/11" target="_blank">https://digitalcommons.bryant.edu/honors_science/11</a> <a href="#fnref:191" class="footnote-back-ref">↩</a></p></li> <li id="fn:192"><p>Royer, Dana L. (2006). "CO2-forced climate thresholds during the Phanerozoic" (PDF). Geochimica et Cosmochimica Acta. 70 (23): 5665–75. Bibcode:2006GeCoA..70.5665R. doi:10.1016/j.gca.2005.11.031. Archived from the original (PDF) on 27 September 2019. Retrieved 6 August 2015. <a href="https://web.archive.org/web/20190927033455/http://droyer.web.wesleyan.edu/PhanCO2%28GCA%29.pdf" target="_blank">https://web.archive.org/web/20190927033455/http://droyer.web.wesleyan.edu/PhanCO2%28GCA%29.pdf</a> <a href="#fnref:192" class="footnote-back-ref">↩</a></p></li> <li id="fn:193"><p>For more information on this, see Atmosphere of Earth#Evolution of Earth's atmosphere, Carbon dioxide in the Earth's atmosphere, and climate change. Specific graphs of reconstructed CO2 levels over the past ~550, 65, and 5 million years can be seen at File:Phanerozoic Carbon Dioxide.png, File:65 Myr Climate Change.png, File:Five Myr Climate Change.png, respectively. <a href="/wiki/Atmosphere_of_Earth#Evolution_of_Earth's_atmosphere" target="_blank">/wiki/Atmosphere_of_Earth#Evolution_of_Earth's_atmosphere</a> <a href="#fnref:193" class="footnote-back-ref">↩</a></p></li> <li id="fn:194"><p>"Here's What the Last Common Ancestor of Apes and Humans Looked Like". Live Science. 10 August 2017. <a href="https://www.livescience.com/60093-last-common-ancestor-of-apes-humans-revealed.html" target="_blank">https://www.livescience.com/60093-last-common-ancestor-of-apes-humans-revealed.html</a> <a href="#fnref:194" class="footnote-back-ref">↩</a></p></li> <li id="fn:195"><p>Nengo, Isaiah; Tafforeau, Paul; Gilbert, Christopher C.; Fleagle, John G.; Miller, Ellen R.; Feibel, Craig; Fox, David L.; Feinberg, Josh; Pugh, Kelsey D.; Berruyer, Camille; Mana, Sara (2017). "New infant cranium from the African Miocene sheds light on ape evolution". Nature. 548 (7666): 169–174. Bibcode:2017Natur.548..169N. doi:10.1038/nature23456. ISSN 0028-0836. PMID 28796200. S2CID 4397839. <a href="http://www.nature.com/articles/nature23456" target="_blank">http://www.nature.com/articles/nature23456</a> <a href="#fnref:195" class="footnote-back-ref">↩</a></p></li> <li id="fn:196"><p>Deconto, Robert M.; Pollard, David (2003). "Rapid Cenozoic glaciation of Antarctica induced by declining atmospheric CO2" (PDF). Nature. 421 (6920): 245–249. Bibcode:2003Natur.421..245D. doi:10.1038/nature01290. PMID 12529638. S2CID 4326971. <a href="http://doc.rero.ch/record/16546/files/PAL_E3220.pdf" target="_blank">http://doc.rero.ch/record/16546/files/PAL_E3220.pdf</a> <a href="#fnref:196" class="footnote-back-ref">↩</a></p></li> <li id="fn:197"><p>Royer, Dana L. (2006). "CO2-forced climate thresholds during the Phanerozoic" (PDF). Geochimica et Cosmochimica Acta. 70 (23): 5665–75. Bibcode:2006GeCoA..70.5665R. doi:10.1016/j.gca.2005.11.031. Archived from the original (PDF) on 27 September 2019. Retrieved 6 August 2015. <a href="https://web.archive.org/web/20190927033455/http://droyer.web.wesleyan.edu/PhanCO2%28GCA%29.pdf" target="_blank">https://web.archive.org/web/20190927033455/http://droyer.web.wesleyan.edu/PhanCO2%28GCA%29.pdf</a> <a href="#fnref:197" class="footnote-back-ref">↩</a></p></li> <li id="fn:198"><p>For more information on this, see Atmosphere of Earth#Evolution of Earth's atmosphere, Carbon dioxide in the Earth's atmosphere, and climate change. Specific graphs of reconstructed CO2 levels over the past ~550, 65, and 5 million years can be seen at File:Phanerozoic Carbon Dioxide.png, File:65 Myr Climate Change.png, File:Five Myr Climate Change.png, respectively. <a href="/wiki/Atmosphere_of_Earth#Evolution_of_Earth's_atmosphere" target="_blank">/wiki/Atmosphere_of_Earth#Evolution_of_Earth's_atmosphere</a> <a href="#fnref:198" class="footnote-back-ref">↩</a></p></li> <li id="fn:199"><p>Royer, Dana L. (2006). "CO2-forced climate thresholds during the Phanerozoic" (PDF). Geochimica et Cosmochimica Acta. 70 (23): 5665–75. Bibcode:2006GeCoA..70.5665R. doi:10.1016/j.gca.2005.11.031. Archived from the original (PDF) on 27 September 2019. Retrieved 6 August 2015. <a href="https://web.archive.org/web/20190927033455/http://droyer.web.wesleyan.edu/PhanCO2%28GCA%29.pdf" target="_blank">https://web.archive.org/web/20190927033455/http://droyer.web.wesleyan.edu/PhanCO2%28GCA%29.pdf</a> <a href="#fnref:199" class="footnote-back-ref">↩</a></p></li> <li id="fn:200"><p>For more information on this, see Atmosphere of Earth#Evolution of Earth's atmosphere, Carbon dioxide in the Earth's atmosphere, and climate change. Specific graphs of reconstructed CO2 levels over the past ~550, 65, and 5 million years can be seen at File:Phanerozoic Carbon Dioxide.png, File:65 Myr Climate Change.png, File:Five Myr Climate Change.png, respectively. <a href="/wiki/Atmosphere_of_Earth#Evolution_of_Earth's_atmosphere" target="_blank">/wiki/Atmosphere_of_Earth#Evolution_of_Earth's_atmosphere</a> <a href="#fnref:200" class="footnote-back-ref">↩</a></p></li> <li id="fn:201"><p>Medlin, L. K.; Kooistra, W. H. C. F.; Gersonde, R.; Sims, P. A.; Wellbrock, U. (1997). "Is the origin of the diatoms related to the end-Permian mass extinction?". Nova Hedwigia. 65 (1–4): 1–11. doi:10.1127/nova.hedwigia/65/1997/1. hdl:10013/epic.12689. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:201" class="footnote-back-ref">↩</a></p></li> <li id="fn:202"><p>The Mississippian and Pennsylvanian are official sub-systems/sub-periods. <a href="/wiki/Mississippian_(geology)" target="_blank">/wiki/Mississippian_(geology)</a> <a href="#fnref:202" class="footnote-back-ref">↩</a></p></li> <li id="fn:203"><p>This is divided into Lower/Early, Middle, and Upper/Late series/epochs <a href="#fnref:203" class="footnote-back-ref">↩</a></p></li> <li id="fn:204"><p>This is divided into Lower/Early, Middle, and Upper/Late series/epochs <a href="#fnref:204" class="footnote-back-ref">↩</a></p></li> <li id="fn:205"><p>Royer, Dana L. (2006). "CO2-forced climate thresholds during the Phanerozoic" (PDF). Geochimica et Cosmochimica Acta. 70 (23): 5665–75. Bibcode:2006GeCoA..70.5665R. doi:10.1016/j.gca.2005.11.031. Archived from the original (PDF) on 27 September 2019. Retrieved 6 August 2015. <a href="https://web.archive.org/web/20190927033455/http://droyer.web.wesleyan.edu/PhanCO2%28GCA%29.pdf" target="_blank">https://web.archive.org/web/20190927033455/http://droyer.web.wesleyan.edu/PhanCO2%28GCA%29.pdf</a> <a href="#fnref:205" class="footnote-back-ref">↩</a></p></li> <li id="fn:206"><p>For more information on this, see Atmosphere of Earth#Evolution of Earth's atmosphere, Carbon dioxide in the Earth's atmosphere, and climate change. Specific graphs of reconstructed CO2 levels over the past ~550, 65, and 5 million years can be seen at File:Phanerozoic Carbon Dioxide.png, File:65 Myr Climate Change.png, File:Five Myr Climate Change.png, respectively. <a href="/wiki/Atmosphere_of_Earth#Evolution_of_Earth's_atmosphere" target="_blank">/wiki/Atmosphere_of_Earth#Evolution_of_Earth's_atmosphere</a> <a href="#fnref:206" class="footnote-back-ref">↩</a></p></li> <li id="fn:207"><p>Williams, Joshua J.; Mills, Benjamin J. W.; Lenton, Timothy M. (2019). "A tectonically driven Ediacaran oxygenation event". Nature Communications. 10 (1): 2690. Bibcode:2019NatCo..10.2690W. doi:10.1038/s41467-019-10286-x. ISSN 2041-1723. PMC 6584537. PMID 31217418. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6584537" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6584537</a> <a href="#fnref:207" class="footnote-back-ref">↩</a></p></li> <li id="fn:208"><p>Naranjo-Ortiz, Miguel A.; Gabaldón, Toni (25 April 2019). "Fungal evolution: major ecological adaptations and evolutionary transitions". Biological Reviews of the Cambridge Philosophical Society. 94 (4). Cambridge Philosophical Society (Wiley): 1443–1476. doi:10.1111/brv.12510. ISSN 1464-7931. PMC 6850671. PMID 31021528. S2CID 131775942. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6850671" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6850671</a> <a href="#fnref:208" class="footnote-back-ref">↩</a></p></li> <li id="fn:209"><p>Žárský, Jakub; Žárský, Vojtěch; Hanáček, Martin; Žárský, Viktor (27 January 2022). "Cryogenian Glacial Habitats as a Plant Terrestrialisation Cradle – The Origin of the Anydrophytes and Zygnematophyceae Split". Frontiers in Plant Science. 12: 735020. doi:10.3389/fpls.2021.735020. ISSN 1664-462X. PMC 8829067. PMID 35154170. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8829067" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8829067</a> <a href="#fnref:209" class="footnote-back-ref">↩</a></p></li> <li id="fn:210"><p>Yoon, Hwan Su; Hackett, Jeremiah D.; Ciniglia, Claudia; Pinto, Gabriele; Bhattacharya, Debashish (2004). "A Molecular Timeline for the Origin of Photosynthetic Eukaryotes". Molecular Biology and Evolution. 21 (5): 809–818. doi:10.1093/molbev/msh075. ISSN 1537-1719. PMID 14963099. <a href="https://academic.oup.com/mbe/article-lookup/doi/10.1093/molbev/msh075" target="_blank">https://academic.oup.com/mbe/article-lookup/doi/10.1093/molbev/msh075</a> <a href="#fnref:210" class="footnote-back-ref">↩</a></p></li> <li id="fn:211"><p>Och, Lawrence M.; Shields-Zhou, Graham A. (1 January 2012). "The Neoproterozoic oxygenation event: Environmental perturbations and biogeochemical cycling". Earth-Science Reviews. 110 (1–4): 26–57. doi:10.1016/j.earscirev.2011.09.004. <a href="https://linkinghub.elsevier.com/retrieve/pii/S0012825211001498" target="_blank">https://linkinghub.elsevier.com/retrieve/pii/S0012825211001498</a> <a href="#fnref:211" class="footnote-back-ref">↩</a></p></li> <li id="fn:212"><p>Defined by absolute age (Global Standard Stratigraphic Age). <a href="/wiki/Global_Standard_Stratigraphic_Age" target="_blank">/wiki/Global_Standard_Stratigraphic_Age</a> <a href="#fnref:212" class="footnote-back-ref">↩</a></p></li> <li id="fn:213"><p>Defined by absolute age (Global Standard Stratigraphic Age). <a href="/wiki/Global_Standard_Stratigraphic_Age" target="_blank">/wiki/Global_Standard_Stratigraphic_Age</a> <a href="#fnref:213" class="footnote-back-ref">↩</a></p></li> <li id="fn:214"><p>Defined by absolute age (Global Standard Stratigraphic Age). <a href="/wiki/Global_Standard_Stratigraphic_Age" target="_blank">/wiki/Global_Standard_Stratigraphic_Age</a> <a href="#fnref:214" class="footnote-back-ref">↩</a></p></li> <li id="fn:215"><p>Defined by absolute age (Global Standard Stratigraphic Age). <a href="/wiki/Global_Standard_Stratigraphic_Age" target="_blank">/wiki/Global_Standard_Stratigraphic_Age</a> <a href="#fnref:215" class="footnote-back-ref">↩</a></p></li> <li id="fn:216"><p>Defined by absolute age (Global Standard Stratigraphic Age). <a href="/wiki/Global_Standard_Stratigraphic_Age" target="_blank">/wiki/Global_Standard_Stratigraphic_Age</a> <a href="#fnref:216" class="footnote-back-ref">↩</a></p></li> <li id="fn:217"><p>Defined by absolute age (Global Standard Stratigraphic Age). <a href="/wiki/Global_Standard_Stratigraphic_Age" target="_blank">/wiki/Global_Standard_Stratigraphic_Age</a> <a href="#fnref:217" class="footnote-back-ref">↩</a></p></li> <li id="fn:218"><p>Defined by absolute age (Global Standard Stratigraphic Age). <a href="/wiki/Global_Standard_Stratigraphic_Age" target="_blank">/wiki/Global_Standard_Stratigraphic_Age</a> <a href="#fnref:218" class="footnote-back-ref">↩</a></p></li> <li id="fn:219"><p>Defined by absolute age (Global Standard Stratigraphic Age). <a href="/wiki/Global_Standard_Stratigraphic_Age" target="_blank">/wiki/Global_Standard_Stratigraphic_Age</a> <a href="#fnref:219" class="footnote-back-ref">↩</a></p></li> <li id="fn:220"><p>Defined by absolute age (Global Standard Stratigraphic Age). <a href="/wiki/Global_Standard_Stratigraphic_Age" target="_blank">/wiki/Global_Standard_Stratigraphic_Age</a> <a href="#fnref:220" class="footnote-back-ref">↩</a></p></li> <li id="fn:221"><p>Defined by absolute age (Global Standard Stratigraphic Age). <a href="/wiki/Global_Standard_Stratigraphic_Age" target="_blank">/wiki/Global_Standard_Stratigraphic_Age</a> <a href="#fnref:221" class="footnote-back-ref">↩</a></p></li> <li id="fn:222"><p>The age of the oldest measurable craton, or continental crust, is dated to 3,600–3,800 Ma. <a href="/wiki/Craton" target="_blank">/wiki/Craton</a> <a href="#fnref:222" class="footnote-back-ref">↩</a></p></li> <li id="fn:223"><p>Defined by absolute age (Global Standard Stratigraphic Age). <a href="/wiki/Global_Standard_Stratigraphic_Age" target="_blank">/wiki/Global_Standard_Stratigraphic_Age</a> <a href="#fnref:223" class="footnote-back-ref">↩</a></p></li> <li id="fn:224"><p>Defined by absolute age (Global Standard Stratigraphic Age). <a href="/wiki/Global_Standard_Stratigraphic_Age" target="_blank">/wiki/Global_Standard_Stratigraphic_Age</a> <a href="#fnref:224" class="footnote-back-ref">↩</a></p></li> <li id="fn:225"><p>Bowring, Samuel A.; Williams, Ian S. (1999). "Priscoan (4.00–4.03 Ga) orthogneisses from northwestern Canada". Contributions to Mineralogy and Petrology. 134 (1): 3. Bibcode:1999CoMP..134....3B. doi:10.1007/s004100050465. S2CID 128376754. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:225" class="footnote-back-ref">↩</a></p></li> <li id="fn:226"><p>Iizuka, Tsuyoshi; Komiya, Tsuyoshi; Maruyama, Shigenori (2007), Chapter 3.1 the Early Archean Acasta Gneiss Complex: Geological, Geochronological and Isotopic Studies and Implications for Early Crustal Evolution, Developments in Precambrian Geology, vol. 15, Elsevier, pp. 127–147, doi:10.1016/s0166-2635(07)15031-3, ISBN 978-0-444-52810-0, retrieved 1 May 2022 <a href="978-0-444-52810-0" target="_blank">978-0-444-52810-0</a> <a href="#fnref:226" class="footnote-back-ref">↩</a></p></li> <li id="fn:227"><p>Wilde, Simon A.; Valley, John W.; Peck, William H.; Graham, Colin M. (2001). "Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago". Nature. 409 (6817): 175–178. doi:10.1038/35051550. ISSN 0028-0836. PMID 11196637. S2CID 4319774. <a href="http://www.nature.com/articles/35051550" target="_blank">http://www.nature.com/articles/35051550</a> <a href="#fnref:227" class="footnote-back-ref">↩</a></p></li> <li id="fn:228"><p>Defined by absolute age (Global Standard Stratigraphic Age). <a href="/wiki/Global_Standard_Stratigraphic_Age" target="_blank">/wiki/Global_Standard_Stratigraphic_Age</a> <a href="#fnref:228" class="footnote-back-ref">↩</a></p></li> <li id="fn:229"><p>Not enough is known about extra-solar planets for worthwhile speculation. <a href="#fnref:229" class="footnote-back-ref">↩</a></p></li> <li id="fn:230"><p>Wilhelms, Don E. (1987). The geologic history of the Moon. Professional Paper. United States Geological Survey. doi:10.3133/pp1348. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:230" class="footnote-back-ref">↩</a></p></li> <li id="fn:231"><p>Tanaka, Kenneth L. (1986). "The stratigraphy of Mars". Journal of Geophysical Research. 91 (B13): E139. Bibcode:1986JGR....91E.139T. doi:10.1029/JB091iB13p0E139. ISSN 0148-0227. <a href="http://doi.wiley.com/10.1029/JB091iB13p0E139" target="_blank">http://doi.wiley.com/10.1029/JB091iB13p0E139</a> <a href="#fnref:231" class="footnote-back-ref">↩</a></p></li> <li id="fn:232"><p>Carr, Michael H.; Head, James W. (1 June 2010). "Geologic history of Mars". Earth and Planetary Science Letters. Mars Express after 6 Years in Orbit: Mars Geology from Three-Dimensional Mapping by the High Resolution Stereo Camera (HRSC) Experiment. 294 (3): 185–203. Bibcode:2010E&PSL.294..185C. doi:10.1016/j.epsl.2009.06.042. ISSN 0012-821X. <a href="https://www.sciencedirect.com/science/article/pii/S0012821X09003847" target="_blank">https://www.sciencedirect.com/science/article/pii/S0012821X09003847</a> <a href="#fnref:232" class="footnote-back-ref">↩</a></p></li> <li id="fn:233"><p>Bibring, Jean-Pierre; Langevin, Yves; Mustard, John F.; Poulet, François; Arvidson, Raymond; Gendrin, Aline; Gondet, Brigitte; Mangold, Nicolas; Pinet, P.; Forget, F.; Berthé, Michel (21 April 2006). "Global Mineralogical and Aqueous Mars History Derived from OMEGA/Mars Express Data". Science. 312 (5772): 400–404. Bibcode:2006Sci...312..400B. doi:10.1126/science.1122659. ISSN 0036-8075. PMID 16627738. S2CID 13968348. <a href="https://www.science.org/doi/10.1126/science.1122659" target="_blank">https://www.science.org/doi/10.1126/science.1122659</a> <a href="#fnref:233" class="footnote-back-ref">↩</a></p></li> </ol>