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data-event-name="pinnable-header.vector-toc.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-toc.unpin">hide</button> </div> <ul class="vector-toc-contents" id="mw-panel-toc-list"> <li id="toc-mw-content-text" class="vector-toc-list-item vector-toc-level-1"> <a href="#" class="vector-toc-link"> <div class="vector-toc-text">(Top)</div> </a> </li> <li id="toc-Geology" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Geology"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>Geology</span> </div> </a> <button aria-controls="toc-Geology-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Geology subsection</span> </button> <ul id="toc-Geology-sublist" class="vector-toc-list"> <li id="toc-Principles_of_relative_dating" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Principles_of_relative_dating"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1</span> <span>Principles of relative dating</span> </div> </a> <ul id="toc-Principles_of_relative_dating-sublist" class="vector-toc-list"> <li id="toc-Uniformitarianism" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Uniformitarianism"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1.1</span> <span>Uniformitarianism</span> </div> </a> <ul id="toc-Uniformitarianism-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Intrusive_relationships" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Intrusive_relationships"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1.2</span> <span>Intrusive relationships</span> </div> </a> <ul id="toc-Intrusive_relationships-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Cross-cutting_relationships" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Cross-cutting_relationships"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1.3</span> <span>Cross-cutting relationships</span> </div> </a> <ul id="toc-Cross-cutting_relationships-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Inclusions_and_components" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Inclusions_and_components"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1.4</span> <span>Inclusions and components</span> </div> </a> <ul id="toc-Inclusions_and_components-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Original_horizontality" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Original_horizontality"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1.5</span> <span>Original horizontality</span> </div> </a> <ul id="toc-Original_horizontality-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Superposition" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Superposition"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1.6</span> <span>Superposition</span> </div> </a> <ul id="toc-Superposition-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Faunal_succession" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Faunal_succession"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1.7</span> <span>Faunal succession</span> </div> </a> <ul id="toc-Faunal_succession-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Lateral_continuity" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Lateral_continuity"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1.8</span> <span>Lateral continuity</span> </div> </a> <ul id="toc-Lateral_continuity-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Inclusions_of_igneous_rocks" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Inclusions_of_igneous_rocks"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1.9</span> <span>Inclusions of igneous rocks</span> </div> </a> <ul id="toc-Inclusions_of_igneous_rocks-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Included_fragments" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Included_fragments"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1.10</span> <span>Included fragments</span> </div> </a> <ul id="toc-Included_fragments-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Planetology" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Planetology"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.2</span> <span>Planetology</span> </div> </a> <ul id="toc-Planetology-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Archaeology" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Archaeology"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Archaeology</span> </div> </a> <ul id="toc-Archaeology-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Citations" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Citations"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Citations</span> </div> </a> <ul id="toc-Citations-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Relative dating</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 23 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-23" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">23 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%AA%D8%A3%D8%B1%D9%8A%D8%AE_%D9%86%D8%B3%D8%A8%D9%8A" title="تأريخ نسبي – Arabic" lang="ar" hreflang="ar" data-title="تأريخ نسبي" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Dataci%C3%B3_relativa" title="Datació relativa – Catalan" lang="ca" hreflang="ca" data-title="Datació relativa" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Relativn%C3%AD_datov%C3%A1n%C3%AD" title="Relativní datování – Czech" lang="cs" hreflang="cs" data-title="Relativní datování" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Relative_Chronologie" title="Relative Chronologie – German" lang="de" hreflang="de" data-title="Relative Chronologie" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Suhteline_ajaarvamine" title="Suhteline ajaarvamine – Estonian" lang="et" hreflang="et" data-title="Suhteline ajaarvamine" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%A3%CF%87%CE%B5%CF%84%CE%B9%CE%BA%CE%AE_%CF%87%CF%81%CE%BF%CE%BD%CE%BF%CE%BB%CF%8C%CE%B3%CE%B7%CF%83%CE%B7" title="Σχετική χρονολόγηση – Greek" lang="el" hreflang="el" data-title="Σχετική χρονολόγηση" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Dataci%C3%B3n_relativa" title="Datación relativa – Spanish" lang="es" hreflang="es" data-title="Datación relativa" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Relativa_kronologio" title="Relativa kronologio – Esperanto" lang="eo" hreflang="eo" data-title="Relativa kronologio" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%AA%D8%A7%D8%B1%DB%8C%D8%AE%E2%80%8C%DA%AF%D8%B0%D8%A7%D8%B1%DB%8C_%D9%86%D8%B3%D8%A8%DB%8C" title="تاریخ‌گذاری نسبی – Persian" lang="fa" hreflang="fa" data-title="تاریخ‌گذاری نسبی" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Datation_relative" title="Datation relative – French" lang="fr" hreflang="fr" data-title="Datation relative" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Penanggalan_relatif_dalam_geologi" title="Penanggalan relatif dalam geologi – Indonesian" lang="id" hreflang="id" data-title="Penanggalan relatif dalam geologi" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/Afst%C3%A6%C3%B0ur_aldur" title="Afstæður aldur – Icelandic" lang="is" hreflang="is" data-title="Afstæður aldur" data-language-autonym="Íslenska" data-language-local-name="Icelandic" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Cronologia_relativa" title="Cronologia relativa – Italian" lang="it" hreflang="it" data-title="Cronologia relativa" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Relatieve_chronologie" title="Relatieve chronologie – Dutch" lang="nl" hreflang="nl" data-title="Relatieve chronologie" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E7%9B%B8%E5%AF%BE%E5%B9%B4%E4%BB%A3" title="相対年代 – Japanese" lang="ja" hreflang="ja" data-title="相対年代" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Relativ_datering" title="Relativ datering – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Relativ datering" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-ps mw-list-item"><a href="https://ps.wikipedia.org/wiki/%D9%86%D8%B3%D8%A8%D9%8A_%D8%AA%D8%A7%D8%B1%DB%8C%D8%AE_%D9%BC%D8%A7%DA%A9%D9%86%D9%87" title="نسبي تاریخ ټاکنه – Pashto" lang="ps" hreflang="ps" data-title="نسبي تاریخ ټاکنه" data-language-autonym="پښتو" data-language-local-name="Pashto" class="interlanguage-link-target"><span>پښتو</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Datowanie_wzgl%C4%99dne" title="Datowanie względne – Polish" lang="pl" hreflang="pl" data-title="Datowanie względne" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Data%C3%A7%C3%A3o_relativa" title="Datação relativa – Portuguese" lang="pt" hreflang="pt" data-title="Datação relativa" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Relative_dating" title="Relative dating – Simple English" lang="en-simple" hreflang="en-simple" data-title="Relative dating" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sd mw-list-item"><a href="https://sd.wikipedia.org/wiki/%D8%AA%D8%A7%D8%B1%D9%8A%D8%AE_%D9%BE%D9%8A%D9%85%D8%A7%D8%A6%D9%8A_%D8%AC%D8%A7_%D8%A7%D8%B6%D8%A7%D9%81%D9%8A_%D8%B7%D8%B1%D9%8A%D9%82%D8%A7" title="تاريخ پيمائي جا اضافي طريقا – Sindhi" lang="sd" hreflang="sd" data-title="تاريخ پيمائي جا اضافي طريقا" data-language-autonym="سنڌي" data-language-local-name="Sindhi" class="interlanguage-link-target"><span>سنڌي</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/X%C3%A1c_%C4%91%E1%BB%8Bnh_ni%C3%AAn_%C4%91%E1%BA%A1i_t%C6%B0%C6%A1ng_%C4%91%E1%BB%91i" title="Xác định niên đại tương đối – Vietnamese" lang="vi" hreflang="vi" data-title="Xác định niên đại tương đối" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E7%9B%B8%E5%AF%B9%E5%AE%9A%E5%B9%B4" title="相对定年 – Chinese" lang="zh" hreflang="zh" data-title="相对定年" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q265619#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Namespaces"> <div id="p-associated-pages" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-associated-pages" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-nstab-main" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/Relative_dating" title="View the content page [c]" accesskey="c"><span>Article</span></a></li><li id="ca-talk" 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class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Determining the relative order of past events</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">Not to be confused with <a href="/wiki/Incest" title="Incest">Incest</a> or <a href="/wiki/Cousin_marriage" title="Cousin marriage">Cousin marriage</a>.</div><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">For the relative dating of words and sound in languages, see <a href="/wiki/Historical_linguistics" title="Historical linguistics">Historical linguistics</a>.</div> <figure typeof="mw:File/Thumb"><a href="/wiki/File:SEUtahStrat.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/66/SEUtahStrat.JPG/250px-SEUtahStrat.JPG" decoding="async" width="250" height="142" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/66/SEUtahStrat.JPG/375px-SEUtahStrat.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/66/SEUtahStrat.JPG/500px-SEUtahStrat.JPG 2x" data-file-width="3161" data-file-height="1794" /></a><figcaption>The <a href="/wiki/Permian" title="Permian">Permian</a> through <a href="/wiki/Jurassic" title="Jurassic">Jurassic</a> <a href="/wiki/Stratigraphy" title="Stratigraphy">stratigraphy</a> of the <a href="/wiki/Colorado_Plateau" title="Colorado Plateau">Colorado Plateau</a> area of southeastern <a href="/wiki/Utah" title="Utah">Utah</a> is a great example of Original Horizontality and the Law of Superposition, two important ideas used in relative dating. These strata make up much of the famous prominent rock formations in widely spaced protected areas such as <a href="/wiki/Capitol_Reef_National_Park" title="Capitol Reef National Park">Capitol Reef National Park</a> and <a href="/wiki/Canyonlands_National_Park" title="Canyonlands National Park">Canyonlands National Park</a>. From top to bottom: Rounded tan domes of the <a href="/wiki/Navajo_Sandstone" title="Navajo Sandstone">Navajo Sandstone</a>, layered red <a href="/wiki/Kayenta_Formation" title="Kayenta Formation">Kayenta Formation</a>, cliff-forming, vertically jointed, red <a href="/wiki/Wingate_Sandstone" title="Wingate Sandstone">Wingate Sandstone</a>, slope-forming, purplish <a href="/wiki/Chinle_Formation" title="Chinle Formation">Chinle Formation</a>, layered, lighter-red <a href="/wiki/Moenkopi_Formation" title="Moenkopi Formation">Moenkopi Formation</a>, and white, layered <a href="/wiki/Cutler_Formation" title="Cutler Formation">Cutler Formation</a> sandstone. Photo from <a href="/wiki/Glen_Canyon_National_Recreation_Area" title="Glen Canyon National Recreation Area">Glen Canyon National Recreation Area</a>, Utah.</figcaption></figure> <p><b>Relative dating</b> is the science of determining the relative order of past events (i.e., the age of an object in comparison to another), without necessarily determining their <a href="/wiki/Absolute_age" class="mw-redirect" title="Absolute age">absolute age</a> (i.e., estimated age). In geology, <a href="/wiki/Rock_(geology)" title="Rock (geology)">rock</a> or <a href="/wiki/Superficial_deposits" title="Superficial deposits">superficial deposits</a>, <a href="/wiki/Fossil" title="Fossil">fossils</a> and <a href="/wiki/Lithology" title="Lithology">lithologies</a> can be used to correlate one <a href="/wiki/Stratigraphic_column" title="Stratigraphic column">stratigraphic column</a> with another. Prior to the discovery of <a href="/wiki/Radiometric_dating" title="Radiometric dating">radiometric dating</a> in the early 20th century, which provided a means of <a href="/wiki/Absolute_dating" title="Absolute dating">absolute dating</a>, <a href="/wiki/Archaeologists" class="mw-redirect" title="Archaeologists">archaeologists</a> and <a href="/wiki/Geologist" title="Geologist">geologists</a> used relative dating to <a href="/wiki/Chronological_dating" title="Chronological dating">determine ages</a> of materials. Though relative dating can only determine the <i>sequential order</i> in which a series of events occurred, not <i>when</i> they occurred, it remains a useful technique. Relative dating by <a href="/wiki/Biostratigraphy" title="Biostratigraphy">biostratigraphy</a> is the preferred method in <a href="/wiki/Paleontology" title="Paleontology">paleontology</a> and is, in some respects, more accurate.<sup id="cite_ref-Stanley99_1-0" class="reference"><a href="#cite_note-Stanley99-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> The <a href="/wiki/Law_of_Superposition" class="mw-redirect" title="Law of Superposition">Law of Superposition</a>, which states that older layers will be deeper in a site than more recent layers, was the summary outcome of 'relative dating' as observed in geology from the 17th century to the early 20th century. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Geology">Geology</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=1" title="Edit section: Geology"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The regular order of the occurrence of fossils in rock layers was discovered around 1800 by <a href="/wiki/William_Smith_(geologist)" title="William Smith (geologist)">William Smith</a>. While digging the <a href="/wiki/Somerset_Coal_Canal" title="Somerset Coal Canal">Somerset Coal Canal</a> in southwest England, he found that fossils were always in the same order in the rock layers. As he continued his job as a <a href="/wiki/Surveying" title="Surveying">surveyor</a>, he found the same patterns across England. He also found that certain animals were in only certain layers and that they were in the same layers all across England. Due to that discovery, Smith was able to recognize the order that the rocks were formed. Sixteen years after his discovery, he published a <a href="/wiki/Geological_map" class="mw-redirect" title="Geological map">geological map</a> of England showing the rocks of different <a href="/wiki/Geologic_time" class="mw-redirect" title="Geologic time">geologic time</a> eras. </p> <div class="mw-heading mw-heading3"><h3 id="Principles_of_relative_dating">Principles of relative dating</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=2" title="Edit section: Principles of relative dating"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Methods for relative dating were developed when geology first emerged as a <a href="/wiki/Natural_science" title="Natural science">natural science</a> in the 18th century. Geologists still use the following principles today as a means to provide information about geologic history and the timing of geologic events. </p> <div class="mw-heading mw-heading4"><h4 id="Uniformitarianism">Uniformitarianism</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=3" title="Edit section: Uniformitarianism"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <i><a href="/wiki/Principle_of_Uniformitarianism" class="mw-redirect" title="Principle of Uniformitarianism">principle of Uniformitarianism</a></i> states that the geologic processes observed in operation that modify the Earth's crust at present have worked in much the same way over geologic time.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> A fundamental principle of geology advanced by the 18th century Scottish physician and geologist <a href="/wiki/James_Hutton" title="James Hutton">James Hutton</a>, is that "the present is the key to the past." In Hutton's words: "the past history of our globe must be explained by what can be seen to be happening now."<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="Intrusive_relationships">Intrusive relationships</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=4" title="Edit section: Intrusive relationships"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <i>principle of <a href="/wiki/Intrusive_rock" title="Intrusive rock">intrusive</a> relationships</i> concerns crosscutting intrusions. In geology, when an <a href="/wiki/Igneous_rocks" class="mw-redirect" title="Igneous rocks">igneous</a> intrusion cuts across a formation of <a href="/wiki/Sedimentary_rock" title="Sedimentary rock">sedimentary rock</a>, it can be determined that the igneous intrusion is younger than the sedimentary rock. There are a number of different types of intrusions, including stocks, <a href="/wiki/Laccolith" title="Laccolith">laccoliths</a>, <a href="/wiki/Batholith" title="Batholith">batholiths</a>, <a href="/wiki/Sill_(geology)" title="Sill (geology)">sills</a> and <a href="/wiki/Dike_(geology)" title="Dike (geology)">dikes</a>. </p> <div class="mw-heading mw-heading4"><h4 id="Cross-cutting_relationships">Cross-cutting relationships</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=5" title="Edit section: Cross-cutting relationships"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Cross-cutting_relations.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Cross-cutting_relations.svg/350px-Cross-cutting_relations.svg.png" decoding="async" width="350" height="189" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Cross-cutting_relations.svg/525px-Cross-cutting_relations.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c6/Cross-cutting_relations.svg/700px-Cross-cutting_relations.svg.png 2x" data-file-width="1000" data-file-height="540" /></a><figcaption><a href="/wiki/Cross-cutting_relations" class="mw-redirect" title="Cross-cutting relations">Cross-cutting relations</a> can be used to determine the relative ages of <a href="/wiki/Stratum" title="Stratum">rock strata</a> and other geological structures. Explanations: A – <a href="/wiki/Fold_(geology)" title="Fold (geology)">folded</a> rock strata cut by a <a href="/wiki/Thrust_fault" title="Thrust fault">thrust fault</a>; B – large <a href="/wiki/Intrusion" class="mw-redirect" title="Intrusion">intrusion</a> (cutting through A); C – <a href="/wiki/Erosion" title="Erosion">erosional</a> <a href="/wiki/Angular_unconformity" class="mw-redirect" title="Angular unconformity">angular unconformity</a> (cutting off A & B) on which rock strata were deposited; D – <a href="/wiki/Dike_(geology)" title="Dike (geology)">volcanic dyke</a> (cutting through A, B & C); E – even younger rock strata (overlying C & D); F – <a href="/wiki/Normal_fault" class="mw-redirect" title="Normal fault">normal fault</a> (cutting through A, B, C & E).</figcaption></figure> <p>The <i><a href="/wiki/Principle_of_cross-cutting_relationships" class="mw-redirect" title="Principle of cross-cutting relationships">principle of cross-cutting relationships</a></i> pertains to the formation of <a href="/wiki/Fault_(geology)" title="Fault (geology)">faults</a> and the age of the sequences through which they cut. Faults are younger than the rocks they cut; accordingly, if a fault is found that penetrates some formations but not those on top of it, then the formations that were cut are older than the fault, and the ones that are not cut must be younger than the fault. Finding the key bed in these situations may help determine whether the fault is a <a href="/wiki/Normal_fault" class="mw-redirect" title="Normal fault">normal fault</a> or a <a href="/wiki/Thrust_fault" title="Thrust fault">thrust fault</a>.<sup id="cite_ref-steno_strat_4-0" class="reference"><a href="#cite_note-steno_strat-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="Inclusions_and_components">Inclusions and components</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=6" title="Edit section: Inclusions and components"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <i><a href="/wiki/Principle_of_inclusions_and_components" class="mw-redirect" title="Principle of inclusions and components">principle of inclusions and components</a></i> explains that, with sedimentary rocks, if inclusions (or <a href="/wiki/Clastic_rocks" class="mw-redirect" title="Clastic rocks">clasts</a>) are found in a formation, then the inclusions must be older than the formation that contains them. For example, in sedimentary rocks, it is common for gravel from an older formation to be ripped up and included in a newer layer. A similar situation with igneous rocks occurs when <a href="/wiki/Xenolith" title="Xenolith">xenoliths</a> are found. These foreign bodies are picked up as <a href="/wiki/Magma" title="Magma">magma</a> or lava flows, and are incorporated, later to cool in the matrix. As a result, xenoliths are older than the rock which contains them. </p> <div class="mw-heading mw-heading4"><h4 id="Original_horizontality">Original horizontality</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=7" title="Edit section: Original horizontality"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <i><a href="/wiki/Principle_of_original_horizontality" title="Principle of original horizontality">principle of original horizontality</a></i> states that the deposition of sediments occurs as essentially horizontal beds. Observation of modern marine and non-marine sediments in a wide variety of environments supports this generalization (although <a href="/wiki/Cross-bedding" title="Cross-bedding">cross-bedding</a> is inclined, the overall orientation of cross-bedded units is horizontal).<sup id="cite_ref-steno_strat_4-1" class="reference"><a href="#cite_note-steno_strat-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="Superposition">Superposition</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=8" title="Edit section: Superposition"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <i><a href="/wiki/Law_of_superposition" title="Law of superposition">law of superposition</a></i> states that a sedimentary rock layer in a tectonically undisturbed sequence is younger than the one beneath it and older than the one above it. This is because it is not possible for a younger layer to slip beneath a layer previously deposited. The only disturbance that the layers experience is bioturbation, in which animals and/or plants move things in the layers. however, this process is not enough to allow the layers to change their positions. This principle allows sedimentary layers to be viewed as a form of vertical time line, a partial or complete record of the time elapsed from deposition of the lowest layer to deposition of the highest bed.<sup id="cite_ref-steno_strat_4-2" class="reference"><a href="#cite_note-steno_strat-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="Faunal_succession">Faunal succession</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=9" title="Edit section: Faunal succession"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <i><a href="/wiki/Principle_of_faunal_succession" title="Principle of faunal succession">principle of faunal succession</a></i> is based on the appearance of fossils in sedimentary rocks. As organisms exist at the same time period throughout the world, their presence or (sometimes) absence may be used to provide a relative age of the formations in which they are found. Based on principles laid out by William Smith almost a hundred years before the publication of <a href="/wiki/Charles_Darwin" title="Charles Darwin">Charles Darwin</a>'s <a href="/wiki/Theory_of_evolution" class="mw-redirect" title="Theory of evolution">theory of evolution</a>, the principles of succession were developed independently of evolutionary thought. The principle becomes quite complex, however, given the uncertainties of fossilization, the localization of fossil types due to lateral changes in habitat (<a href="/wiki/Facies" title="Facies">facies</a> change in sedimentary strata), and that not all fossils may be found globally at the same time.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="Lateral_continuity">Lateral continuity</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=10" title="Edit section: Lateral continuity"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Principle_of_horizontal_continuity.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e0/Principle_of_horizontal_continuity.svg/360px-Principle_of_horizontal_continuity.svg.png" decoding="async" width="360" height="147" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e0/Principle_of_horizontal_continuity.svg/540px-Principle_of_horizontal_continuity.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e0/Principle_of_horizontal_continuity.svg/720px-Principle_of_horizontal_continuity.svg.png 2x" data-file-width="1100" data-file-height="450" /></a><figcaption>Schematic representation of the principle of lateral continuity</figcaption></figure> <p>The <i><a href="/wiki/Principle_of_lateral_continuity" title="Principle of lateral continuity">principle of lateral continuity</a></i> states that layers of <a href="/wiki/Sediment" title="Sediment">sediment</a> initially extend laterally in all directions; in other words, they are laterally continuous. As a result, rocks that are otherwise similar, but are now separated by a <a href="/wiki/Valley" title="Valley">valley</a> or other <a href="/wiki/Erosion" title="Erosion">erosional</a> feature, can be assumed to be originally continuous. </p><p>Layers of sediment do not extend indefinitely; rather, the limits can be recognized and are controlled by the amount and type of <a href="/wiki/Sediment" title="Sediment">sediment</a> available and the size and shape of the <a href="/wiki/Sedimentary_basin" title="Sedimentary basin">sedimentary basin</a>. Sediment will continue to be <a href="/wiki/Sediment_transport" title="Sediment transport">transported</a> to an area and it will eventually be <a href="/wiki/Deposition_(geology)" title="Deposition (geology)">deposited</a>. However, the layer of that material will become thinner as the amount of material lessens away from the source. </p><p>Often, coarser-grained material can no longer be transported to an area because the transporting medium has insufficient energy to carry it to that location. In its place, the particles that settle from the transporting medium will be finer-grained, and there will be a lateral transition from coarser- to finer-grained material. The lateral variation in sediment within a <a href="/wiki/Stratum" title="Stratum">stratum</a> is known as <a href="/wiki/Sedimentary_facies" class="mw-redirect" title="Sedimentary facies">sedimentary facies</a>. </p><p>If sufficient <a href="/wiki/Sedimentary_rock" title="Sedimentary rock">sedimentary</a> material is available, it will be deposited up to the limits of the sedimentary basin. Often, the sedimentary basin is within rocks that are very different from the sediments that are being deposited, in which the lateral limits of the sedimentary layer will be marked by an abrupt change in rock type. </p> <div class="mw-heading mw-heading4"><h4 id="Inclusions_of_igneous_rocks">Inclusions of igneous rocks</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=11" title="Edit section: Inclusions of igneous rocks"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Melt_inclusions_2.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/20/Melt_inclusions_2.jpg/220px-Melt_inclusions_2.jpg" decoding="async" width="220" height="176" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/20/Melt_inclusions_2.jpg/330px-Melt_inclusions_2.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/20/Melt_inclusions_2.jpg/440px-Melt_inclusions_2.jpg 2x" data-file-width="1633" data-file-height="1307" /></a><figcaption>Multiple melt inclusions in an olivine crystal. Individual inclusions are oval or round in shape and consist of clear glass, together with a small round vapor bubble and in some cases a small square spinel crystal. The black arrow points to one good example, but there are several others. The occurrence of multiple inclusions within a single crystal is relatively common</figcaption></figure> <p><a href="/wiki/Melt_inclusions" class="mw-redirect" title="Melt inclusions">Melt inclusions</a> are small parcels or "blobs" of molten rock that are trapped within crystals that grow in the <a href="/wiki/Magma" title="Magma">magmas</a> that form <a href="/wiki/Igneous_rocks" class="mw-redirect" title="Igneous rocks">igneous rocks</a>. In many respects they are analogous to <a href="/wiki/Fluid_inclusions" class="mw-redirect" title="Fluid inclusions">fluid inclusions</a>. Melt inclusions are generally small – most are less than 100 <a href="/wiki/Micrometre" title="Micrometre">micrometres</a> across (a micrometre is one thousandth of a millimeter, or about 0.00004 inches). Nevertheless, they can provide an abundance of useful information. Using microscopic observations and a range of chemical <a href="/wiki/Microanalysis" title="Microanalysis">microanalysis</a> techniques <a href="/wiki/Geochemist" class="mw-redirect" title="Geochemist">geochemists</a> and <a href="/wiki/Petrology" title="Petrology">igneous petrologists</a> can obtain a range of useful information from melt inclusions. Two of the most common uses of melt inclusions are to study the compositions of magmas present early in the history of specific magma systems. This is because inclusions can act like "fossils" – trapping and preserving these early melts before they are modified by later igneous processes. In addition, because they are trapped at high pressures many melt inclusions also provide important information about the contents of volatile elements (such as H<sub>2</sub>O, CO<sub>2</sub>, S and Cl) that drive explosive <a href="/wiki/Volcano" title="Volcano">volcanic eruptions</a>. </p><p><a href="/wiki/Henry_Clifton_Sorby" title="Henry Clifton Sorby">Sorby</a> (1858) was the first to document microscopic melt inclusions in crystals. The study of melt inclusions has been driven more recently by the development of sophisticated chemical analysis techniques. Scientists from the former Soviet Union lead the study of melt inclusions in the decades after <a href="/wiki/World_War_II" title="World War II">World War II</a> (Sobolev and Kostyuk, 1975), and developed methods for heating melt inclusions under a microscope, so changes could be directly observed. </p><p>Although they are small, melt inclusions may contain a number of different constituents, including glass (which represents magma that has been quenched by rapid cooling), small crystals and a separate vapour-rich bubble. They occur in most of the crystals found in igneous rocks and are common in the minerals <a href="/wiki/Quartz" title="Quartz">quartz</a>, <a href="/wiki/Feldspar" title="Feldspar">feldspar</a>, <a href="/wiki/Olivine" title="Olivine">olivine</a> and <a href="/wiki/Pyroxene" title="Pyroxene">pyroxene</a>. The formation of melt inclusions appears to be a normal part of the crystallization of minerals within magmas, and they can be found in both <a href="/wiki/Volcanic" class="mw-redirect" title="Volcanic">volcanic</a> and <a href="/wiki/Pluton" class="mw-redirect" title="Pluton">plutonic</a> rocks. </p> <div class="mw-heading mw-heading4"><h4 id="Included_fragments">Included fragments</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=12" title="Edit section: Included fragments"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <i><a href="/wiki/Law_of_included_fragments" title="Law of included fragments">law of included fragments</a></i> is a method of relative dating in <a href="/wiki/Geology" title="Geology">geology</a>. Essentially, this law states that <a href="/wiki/Clastic_rock" title="Clastic rock">clasts</a> in a rock are older than the rock itself.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> One example of this is a <a href="/wiki/Xenolith" title="Xenolith">xenolith</a>, which is a fragment of <a href="/wiki/Country_rock_(geology)" title="Country rock (geology)">country rock</a> that fell into passing <a href="/wiki/Magma" title="Magma">magma</a> as a result of <a href="/wiki/Stoping_(geology)" title="Stoping (geology)">stoping</a>. Another example is a <a href="/wiki/Derived_fossil" class="mw-redirect" title="Derived fossil">derived fossil</a>, which is a <a href="/wiki/Fossil" title="Fossil">fossil</a> that has been eroded from an older <a href="/wiki/Bed_(geology)" title="Bed (geology)">bed</a> and redeposited into a younger one.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p><p>This is a restatement of <a href="/wiki/Charles_Lyell" title="Charles Lyell">Charles Lyell</a>'s original <i>principle of inclusions and components</i> from his 1830 to 1833 multi-volume <i><a href="/wiki/Principles_of_Geology" title="Principles of Geology">Principles of Geology</a></i>, which states that, with <a href="/wiki/Sedimentary_rock" title="Sedimentary rock">sedimentary rocks</a>, if <a href="/wiki/Inclusion_(mineral)" title="Inclusion (mineral)">inclusions</a> (or clasts) are found in a <a href="/wiki/Formation_(stratigraphy)" class="mw-redirect" title="Formation (stratigraphy)">formation</a>, then the inclusions must be older than the formation that contains them. For example, in sedimentary rocks, it is common for <a href="/wiki/Gravel" title="Gravel">gravel</a> from an older formation to be ripped up and included in a newer layer. A similar situation with <a href="/wiki/Igneous_rock" title="Igneous rock">igneous rocks</a> occurs when xenoliths are found. These foreign bodies are picked up as <a href="/wiki/Igneous_rock" title="Igneous rock">magma</a> or <a href="/wiki/Lava_flow" class="mw-redirect" title="Lava flow">lava flows</a> and are incorporated later to cool in the <a href="/wiki/Matrix_(geology)" title="Matrix (geology)">matrix</a>. As a result, xenoliths are older than the rock which contains them. </p> <div class="mw-heading mw-heading3"><h3 id="Planetology">Planetology</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=13" title="Edit section: Planetology"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Planetary_science#Planetary_geology" title="Planetary science">Planetary science § Planetary geology</a></div> <p>Relative dating is used to determine the order of events on <a href="/wiki/Solar_System_object" class="mw-redirect" title="Solar System object">Solar System objects</a> other than Earth; for decades, <a href="/wiki/Planetary_scientist" class="mw-redirect" title="Planetary scientist">planetary scientists</a> have used it to decipher the development of bodies in the <a href="/wiki/Solar_System" title="Solar System">Solar System</a>, particularly in the vast majority of cases for which we have no surface samples. Many of the same principles are applied. For example, if a valley is formed inside an <a href="/wiki/Impact_crater" title="Impact crater">impact crater</a>, the valley must be younger than the crater. </p><p>Craters are very useful in relative dating; as a general rule, the younger a planetary surface is, the fewer craters it has. If long-term cratering rates are known to enough precision, crude absolute dates can be applied based on craters alone; however, cratering rates outside the Earth-Moon system are poorly known.<sup id="cite_ref-Hartmann99_8-0" class="reference"><a href="#cite_note-Hartmann99-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Archaeology">Archaeology</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=14" title="Edit section: Archaeology"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main articles: <a href="/wiki/Stratigraphy_(archaeology)" title="Stratigraphy (archaeology)">Stratigraphy (archaeology)</a> and <a href="/wiki/Typology_(archaeology)" title="Typology (archaeology)">Typology (archaeology)</a></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/Dating_methodologies_in_archaeology" class="mw-redirect" title="Dating methodologies in archaeology">Dating methodologies in archaeology</a></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/Disturbance_(archaeology)" title="Disturbance (archaeology)">Disturbance (archaeology)</a></div> <p>Relative dating methods in <a href="/wiki/Archaeology" title="Archaeology">archaeology</a> are similar to some of those applied in geology. The principles of typology can be compared to the biostratigraphic approach in geology. </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=15" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Astronomical_chronology" title="Astronomical chronology">Astronomical chronology</a> <ul><li><a href="/wiki/Age_of_the_Earth" class="mw-redirect" title="Age of the Earth">Age of the Earth</a></li> <li><a href="/wiki/Age_of_the_universe" title="Age of the universe">Age of the universe</a></li></ul></li></ul> <ul><li><a href="/wiki/Chronological_dating" title="Chronological dating">Chronological dating</a>, archaeological chronology <ul><li><a href="/wiki/Absolute_dating" title="Absolute dating">Absolute dating</a></li> <li>Relative dating, this article</li> <li><a href="/wiki/Phase_(archaeology)" title="Phase (archaeology)">Phase (archaeology)</a></li> <li><a href="/wiki/Archaeological_association" class="mw-redirect" title="Archaeological association">Archaeological association</a></li> <li><a href="/wiki/Archaeological_context" class="mw-redirect" title="Archaeological context">Archaeological context</a></li> <li><a href="/wiki/Archaeological_culture" title="Archaeological culture">Archaeological culture</a> – Group of artifact types and structure layouts that often occur together</li> <li><a href="/wiki/Relationship_(archaeology)" title="Relationship (archaeology)">Relationship (archaeology)</a> – relationship in space and time between archaeological objects or contexts<span style="display:none" class="category-wikidata-fallback-annotation">Pages displaying wikidata descriptions as a fallback</span></li> <li><a href="/wiki/Seriation_(archaeology)#Archaeological_sequence" title="Seriation (archaeology)">Sequence</a></li> <li><a href="/wiki/Seriation_(archaeology)" title="Seriation (archaeology)">Seriation (archaeology)</a> – Archaeological method of relative dating</li></ul></li></ul> <ul><li><a href="/wiki/Geochronology" title="Geochronology">Geochronology</a> <ul><li><a href="/wiki/Chronostratigraphy" title="Chronostratigraphy">Chronostratigraphy</a> <ul><li><a href="/wiki/Marker_horizon" title="Marker horizon">Marker horizon</a></li> <li><a href="/wiki/Thermochronology" title="Thermochronology">Thermochronology</a></li> <li><a href="/wiki/Stratigraphy" title="Stratigraphy">Stratigraphy</a></li> <li><a href="/wiki/Structural_geology" title="Structural geology">Structural geology</a></li> <li><a href="/wiki/Unconformity" title="Unconformity">Unconformity</a></li></ul></li></ul></li></ul> <ul><li><ul><li><a href="/wiki/Geologic_time_scale" title="Geologic time scale">Geologic time scale</a> <ul><li><a href="/wiki/Geological_history_of_Earth" title="Geological history of Earth">Geological history of Earth</a></li> <li><a href="/wiki/Future_of_the_Earth" class="mw-redirect" title="Future of the Earth">Future of the Earth</a></li></ul></li></ul></li></ul> <ul><li><ul><li><a href="/wiki/Plate_tectonics" title="Plate tectonics">Plate tectonics</a> <ul><li><a href="/wiki/Plate_reconstruction" title="Plate reconstruction">Plate reconstruction</a></li></ul></li></ul></li></ul> <ul><li><ul><li><a href="/wiki/Timeline_of_natural_history" title="Timeline of natural history">Timeline of natural history</a></li> <li><a href="/wiki/List_of_geochronologic_names" title="List of geochronologic names">List of geochronologic names</a></li></ul></li></ul> <ul><li>General <ul><li><a href="/wiki/Consilience" title="Consilience">Consilience</a>, evidence from independent, unrelated sources can "converge" on strong conclusions</li></ul></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=16" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-columns references-column-width" style="column-width: 30em;"> <ol class="references"> <li id="cite_note-Stanley99-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-Stanley99_1-0">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFStanley,_Steven_M.1999" class="citation book cs1">Stanley, Steven M. (1999). <i>Earth System History</i>. New York: W.H. Freeman and Company. pp. 167–169. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-7167-2882-6" title="Special:BookSources/0-7167-2882-6"><bdi>0-7167-2882-6</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Earth+System+History&rft.place=New+York&rft.pages=167-169&rft.pub=W.H.+Freeman+and+Company&rft.date=1999&rft.isbn=0-7167-2882-6&rft.au=Stanley%2C+Steven+M.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ARelative+dating" class="Z3988"></span></span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text">Reijer Hooykaas, <a rel="nofollow" class="external text" href="https://archive.org/details/naturallawdivine0000hooy"><i>Natural Law and Divine Miracle: The Principle of Uniformity in Geology, Biology, and Theology</i></a> <a rel="nofollow" class="external text" href="https://books.google.com/books?id=3TgYAAAAIAAJ">On Google Books</a>, Leiden: <a href="/wiki/EJ_Brill" class="mw-redirect" title="EJ Brill">EJ Brill</a>, 1963.</span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLevin2010" class="citation book cs1">Levin, Harold L. (2010). <i>The earth through time</i> (9th ed.). Hoboken, N.J.: J. Wiley. p. 18. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-470-38774-0" title="Special:BookSources/978-0-470-38774-0"><bdi>978-0-470-38774-0</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+earth+through+time&rft.place=Hoboken%2C+N.J.&rft.pages=18&rft.edition=9th&rft.pub=J.+Wiley&rft.date=2010&rft.isbn=978-0-470-38774-0&rft.aulast=Levin&rft.aufirst=Harold+L.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ARelative+dating" class="Z3988"></span></span> </li> <li id="cite_note-steno_strat-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-steno_strat_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-steno_strat_4-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-steno_strat_4-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFOlsen2001" class="citation web cs1">Olsen, Paul E. (2001). <a rel="nofollow" class="external text" href="http://rainbow.ldeo.columbia.edu/courses/v1001/steno.html">"Steno's Principles of Stratigraphy"</a>. <i>Dinosaurs and the History of Life</i>. Columbia University. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20080509122724/http://rainbow.ldeo.columbia.edu/courses/v1001/steno.html">Archived</a> from the original on 2008-05-09<span class="reference-accessdate">. Retrieved <span class="nowrap">2009-03-14</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Dinosaurs+and+the+History+of+Life&rft.atitle=Steno%27s+Principles+of+Stratigraphy&rft.date=2001&rft.aulast=Olsen&rft.aufirst=Paul+E.&rft_id=http%3A%2F%2Frainbow.ldeo.columbia.edu%2Fcourses%2Fv1001%2Fsteno.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ARelative+dating" class="Z3988"></span></span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text">As recounted in <a href="/wiki/Simon_Winchester" title="Simon Winchester">Simon Winchester</a>, <i><a href="/wiki/The_Map_that_Changed_the_World" title="The Map that Changed the World">The Map that Changed the World</a></i> (New York: HarperCollins, 2001), pp. 59–91.</span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text">See <a rel="nofollow" class="external text" href="http://www.wesleyan.edu/ctgeology/LISproject/Relative%20ages.htm">"Reading Rocks by Wesleyan University"</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110514145516/http://www.wesleyan.edu/ctgeology/LISproject/Relative%20ages.htm">Archived</a> 2011-05-14 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a> retrieved May 8, 2011</span> </li> <li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text">D. Armstrong, F. Mugglestone, R. Richards and F. Stratton, <i>OCR AS and A2 Geology,</i> Pearson Education Limited, 2008, p. 276 <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-435-69211-7" title="Special:BookSources/978-0-435-69211-7">978-0-435-69211-7</a></span> </li> <li id="cite_note-Hartmann99-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-Hartmann99_8-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHartmann,_William_K.1999" class="citation book cs1">Hartmann, William K. (1999). <i>Moons & Planets</i> (4th ed.). Belmont: Wadsworth Publishing Company. p. 258. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-534-54630-7" title="Special:BookSources/0-534-54630-7"><bdi>0-534-54630-7</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Moons+%26+Planets&rft.place=Belmont&rft.pages=258&rft.edition=4th&rft.pub=Wadsworth+Publishing+Company&rft.date=1999&rft.isbn=0-534-54630-7&rft.au=Hartmann%2C+William+K.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ARelative+dating" class="Z3988"></span></span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="Citations">Citations</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Relative_dating&action=edit&section=17" title="Edit section: Citations"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li>"Biostratigraphy: William Smith". Understanding Evolution. 2009. University of California Museum of Paleontology. 23 January 2009 <<a rel="nofollow" class="external free" href="http://evolution.berkeley.edu/evolibrary/article/0_0_0/history_11">http://evolution.berkeley.edu/evolibrary/article/0_0_0/history_11</a>></li> <li>Monroe, James S., and Reed Wicander. <i>The Changing Earth: Exploring Geology and Evolution</i>, 2nd ed. Belmont: West Publishing Company, 1997. <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-314-09577-2" title="Special:BookSources/0-314-09577-2">0-314-09577-2</a></li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul dl,.mw-parser-output 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class="navbox-group" style="width:1%;line-height:1.2em;background:#cc9;"><div class="hlist"><ul><li><a href="/wiki/Periodization" title="Periodization">Periods</a></li><li><a href="/wiki/Era" title="Era">Eras</a></li><li><a href="/wiki/Epoch_(reference_date)" class="mw-redirect" title="Epoch (reference date)">Epochs</a></li></ul></div></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;"><a href="/wiki/Calendar_era" title="Calendar era">Calendar eras</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Holocene_calendar" title="Holocene calendar">Human Era</a></li> <li><i><a href="/wiki/Ab_urbe_condita" title="Ab urbe condita">Ab urbe condita</a></i></li> <li><a href="/wiki/Anno_Domini" title="Anno Domini">Anno Domini</a> / <a href="/wiki/Common_Era" title="Common Era">Common Era</a></li> <li><a href="/wiki/Anno_Mundi" title="Anno Mundi">Anno Mundi</a></li> <li><a href="/wiki/Bosporan_era" title="Bosporan era">Bosporan era</a></li> <li><a href="/wiki/Bostran_era" title="Bostran era">Bostran era</a></li> <li><a href="/wiki/Byzantine_calendar" title="Byzantine calendar">Byzantine era</a></li> <li><a href="/wiki/Seleucid_era" title="Seleucid era">Seleucid era</a></li> <li><a href="/wiki/Era_of_Caesar_(Iberian_Peninsula)" class="mw-redirect" title="Era of Caesar (Iberian Peninsula)">Era of Caesar (Iberia)</a></li> <li><a href="/wiki/Before_present" class="mw-redirect" title="Before present">Before present</a></li> <li><a href="/wiki/Islamic_calendar" title="Islamic calendar">Hijri</a></li> <li><a href="/wiki/Egyptian_chronology" title="Egyptian chronology">Egyptian</a></li> <li><a href="/wiki/Sothic_cycle" title="Sothic cycle">Sothic cycle</a></li> <li><a href="/wiki/Hindu_units_of_time" title="Hindu units of time">Hindu units of time</a> (<a href="/wiki/Yuga" title="Yuga">Yuga</a>)</li> <li><a href="/wiki/Mesoamerican_calendars" title="Mesoamerican calendars">Mesoamerican</a> <ul><li><a href="/wiki/Mesoamerican_Long_Count_calendar" title="Mesoamerican Long Count calendar">Long Count</a></li> <li><a href="/wiki/Maya_calendar#Short_Count" title="Maya calendar">Short Count</a></li> <li><a href="/wiki/Tzolk%27in" class="mw-redirect" title="Tzolk'in">Tzolk'in</a></li> <li><a href="/wiki/Haab%27" class="mw-redirect" title="Haab'">Haab'</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;"><a href="/wiki/Regnal_year" title="Regnal year">Regnal year</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Anka_year" title="Anka year">Anka year</a></li> <li><a href="/wiki/Canon_of_Kings" title="Canon of Kings">Canon of Kings</a></li> <li><a href="/wiki/Regnal_years_of_English_and_British_monarchs" title="Regnal years of English and British monarchs">English and British regnal year</a></li> <li><a href="/wiki/Category:Regnal_lists" title="Category:Regnal lists">Lists of kings</a></li> <li><a href="/wiki/Limmu" title="Limmu">Limmu</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;"><a href="/wiki/Regnal_year" title="Regnal year">Era names</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chinese_era_name" title="Chinese era name">Chinese</a></li> <li><a href="/wiki/Japanese_era_name" title="Japanese era name">Japanese</a></li> <li><a href="/wiki/Korean_era_name" title="Korean era name">Korean</a></li> <li><a href="/wiki/Vietnamese_era_name" title="Vietnamese era name">Vietnamese</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;line-height:1.2em;background:#cc9;"><a href="/wiki/Calendar" title="Calendar">Calendars</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;">Pre-Julian / Julian</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Roman_calendar" title="Roman calendar">Pre-Julian Roman</a></li> <li><a href="/wiki/Julian_calendar" title="Julian calendar">Original Julian</a></li> <li><a href="/wiki/Proleptic_Julian_calendar" title="Proleptic Julian calendar">Proleptic Julian</a></li> <li><a href="/wiki/Revised_Julian_calendar" title="Revised Julian calendar">Revised Julian</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;">Gregorian</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Gregorian_calendar" title="Gregorian calendar">Gregorian</a></li> <li><a href="/wiki/Proleptic_Gregorian_calendar" title="Proleptic Gregorian calendar">Proleptic Gregorian</a></li> <li><a href="/wiki/Old_Style_and_New_Style_dates" title="Old Style and New Style dates">Old Style and New Style dates</a></li> <li><a href="/wiki/Adoption_of_the_Gregorian_calendar" title="Adoption of the Gregorian calendar">Adoption of the Gregorian calendar</a></li> <li><a href="/wiki/Dual_dating" title="Dual dating">Dual dating</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;">Astronomical</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Lunisolar_calendar" title="Lunisolar calendar">Lunisolar</a> (<a href="/wiki/Hebrew_calendar" title="Hebrew calendar">Hebrew</a>, <a href="/wiki/Hindu_calendar" title="Hindu calendar">Hindu</a>)</li> <li><a href="/wiki/Solar_calendar" title="Solar calendar">Solar</a></li> <li><a href="/wiki/Lunar_calendar" title="Lunar calendar">Lunar</a> (<a href="/wiki/Islamic_calendar" title="Islamic calendar">Islamic</a>)</li> <li><a href="/wiki/Astronomical_year_numbering" title="Astronomical year numbering">Astronomical year numbering</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;">Others</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Sexagenary_cycle" title="Sexagenary cycle">Chinese sexagenary cycle</a></li> <li><a href="/wiki/Geologic_Calendar" title="Geologic Calendar">Geologic Calendar</a></li> <li><a href="/wiki/Iranian_calendars" title="Iranian calendars">Iranian</a></li> <li><a href="/wiki/ISO_week_date" title="ISO week date">ISO week date</a></li> <li><a href="/wiki/Mesoamerican_calendars" title="Mesoamerican calendars">Mesoamerican</a> <ul><li><a href="/wiki/Maya_calendar" title="Maya calendar">Maya</a></li> <li><a href="/wiki/Aztec_calendar" title="Aztec calendar">Aztec</a></li></ul></li> <li><a href="/wiki/Winter_count" title="Winter count">Winter count</a></li> <li><a href="/wiki/New_Earth_Time" title="New Earth Time">New Earth Time</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;line-height:1.2em;background:#cc9;"><a href="/wiki/Astronomical_chronology" title="Astronomical chronology">Astronomic time</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0;background:#fff;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Cosmic_Calendar" title="Cosmic Calendar">Cosmic Calendar</a></li> <li><a href="/wiki/Ephemeris" title="Ephemeris">Ephemeris</a></li> <li><a href="/wiki/Galactic_year" title="Galactic year">Galactic year</a></li> <li><a href="/wiki/Metonic_cycle" title="Metonic cycle">Metonic cycle</a></li> <li><a href="/wiki/Milankovitch_cycles" title="Milankovitch cycles">Milankovitch cycles</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;line-height:1.2em;background:#cc9;"><a href="/wiki/Geologic_time_scale" title="Geologic time scale">Geologic time</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;">Concepts</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Deep_time" title="Deep time">Deep time</a></li> <li><a href="/wiki/Geological_history_of_Earth" title="Geological history of Earth">Geological history of Earth</a></li> <li><a href="/wiki/Geologic_time_scale#Terminology" title="Geologic time scale">Geological time units</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;">Standards</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Global_Standard_Stratigraphic_Age" title="Global Standard Stratigraphic Age">Global Standard Stratigraphic Age (GSSA)</a></li> <li><a href="/wiki/Global_Boundary_Stratotype_Section_and_Point" title="Global Boundary Stratotype Section and Point">Global Boundary Stratotype Section and Point (GSSP)</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;">Methods</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chronostratigraphy" title="Chronostratigraphy">Chronostratigraphy</a></li> <li><a href="/wiki/Geochronology" title="Geochronology">Geochronology</a></li> <li><a href="/wiki/Isotope_geochemistry" title="Isotope geochemistry">Isotope geochemistry</a></li> <li><a href="/wiki/Law_of_superposition" title="Law of superposition">Law of superposition</a></li> <li><a href="/wiki/Luminescence_dating" title="Luminescence dating">Luminescence dating</a></li> <li><a href="/wiki/Samarium%E2%80%93neodymium_dating" title="Samarium–neodymium dating">Samarium–neodymium dating</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;line-height:1.2em;background:#cc9;"><a href="/wiki/Chronological_dating" title="Chronological dating">Chronological<br />dating</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;"><a href="/wiki/Absolute_dating" title="Absolute dating">Absolute dating</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Amino_acid_dating" title="Amino acid dating">Amino acid racemisation</a></li> <li><a href="/wiki/Archaeomagnetic_dating" title="Archaeomagnetic dating">Archaeomagnetic dating</a></li> <li><a href="/wiki/Dendrochronology" title="Dendrochronology">Dendrochronology</a></li> <li><a href="/wiki/Ice_core" title="Ice core">Ice core</a></li> <li><a href="/wiki/Incremental_dating" title="Incremental dating">Incremental dating</a></li> <li><a href="/wiki/Lichenometry" title="Lichenometry">Lichenometry</a></li> <li><a href="/wiki/Paleomagnetism" title="Paleomagnetism">Paleomagnetism</a></li> <li><a href="/wiki/Radiometric_dating" title="Radiometric dating">Radiometric dating</a> <ul><li><a href="/wiki/Lead%E2%80%93lead_dating" title="Lead–lead dating">Lead–lead</a></li> <li><a href="/wiki/K%E2%80%93Ar_dating" title="K–Ar dating">Potassium–argon</a></li> <li><a href="/wiki/Radiocarbon_dating" title="Radiocarbon dating">Radiocarbon</a></li> <li><a href="/wiki/Uranium%E2%80%93lead_dating" title="Uranium–lead dating">Uranium–lead</a></li></ul></li> <li><a href="/wiki/Tephrochronology" title="Tephrochronology">Tephrochronology</a></li> <li><a href="/wiki/Luminescence_dating" title="Luminescence dating">Luminescence dating</a></li> <li><a href="/wiki/Thermoluminescence_dating" title="Thermoluminescence dating">Thermoluminescence dating</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:8.0em;font-weight:normal;background:#cc9;"><a class="mw-selflink selflink">Relative dating</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Fluorine_absorption_dating" title="Fluorine absorption dating">Fluorine absorption</a></li> <li><a href="/wiki/Nitrogen_dating" title="Nitrogen dating">Nitrogen dating</a></li> <li><a href="/wiki/Obsidian_hydration_dating" title="Obsidian hydration dating">Obsidian hydration</a></li> <li><a href="/wiki/Seriation_(archaeology)" title="Seriation (archaeology)">Seriation</a></li> <li><a href="/wiki/Stratigraphy_(archaeology)" title="Stratigraphy (archaeology)">Stratigraphy</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;line-height:1.2em;background:#cc9;">Genetic methods</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Molecular_clock" title="Molecular clock">Molecular clock</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;line-height:1.2em;background:#cc9;">Linguistic methods</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Glottochronology" title="Glottochronology">Glottochronology</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;line-height:1.2em;background:#cc9;">Related topics</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chronicle" title="Chronicle">Chronicle</a></li> <li><a href="/wiki/New_Chronology_(Fomenko)" class="mw-redirect" title="New Chronology (Fomenko)">New Chronology</a></li> <li><a href="/wiki/Synchronoptic_view" title="Synchronoptic view">Synchronoptic view</a></li> <li><a href="/wiki/Timeline" title="Timeline">Timeline</a></li> <li><a href="/wiki/Year_zero" title="Year zero">Year zero</a></li> <li><a href="/wiki/Floruit" title="Floruit">Floruit</a></li> <li><a href="/wiki/Terminus_post_quem" title="Terminus post quem">Terminus post quem</a></li> <li><a href="/wiki/ASPRO_chronology" title="ASPRO chronology">ASPRO chronology</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox authority-control" aria-label="Navbox" style="padding:3px"><table class="nowraplinks hlist navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="row" class="navbox-group" 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