Quaternary | Definition, Period, Climate, Animals, Plants, Timeline, & Facts

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border-right-sm border-left-sm open"> <div class="drawer d-flex flex-column open"> <div class="left-rail-section-content"> <div class="topic-left-rail-header text-truncate bg-gray-50 position-relative text-right d-flex align-items-center"> <div class="tlr-title px-20 py-15 text-left"> <em class="material-icons text-gray-400 d-lg-none" data-icon="toc"></em> <a class="font-serif font-weight-bold text-black link-blue" href="https://www.britannica.com/science/Quaternary">Quaternary</a> </div> <button aria-label="Close" class="js-sections-close-button btn-link btn-sm btn d-lg-none position-absolute top-0 p-10 right-0" > <em class="material-icons font-26" data-icon="close"></em> </button> </div> <div class="section-content pl-10 pr-20 pl-sm-50 pr-sm-60 pl-lg-5 pr-lg-10 pt-10 pt-lg-0 bg-gray-50 clear-catfish-ad"> <div class="toc mb-20"> <div class="font-serif font-14 font-weight-bold mx-15 mb-15 mt-20"> Table of Contents </div> <ul class="list-unstyled my-0" data-level="h1"><li data-target="#ref1"><div class="pl-25"><a class="link-gray-900 w-100" href="/science/Quaternary">Introduction</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref260437"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/Quaternary/The-Quaternary-environment">The Quaternary environment</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref260438"><a class="w-100 link-gray-900" href="/science/Quaternary/The-Quaternary-environment#ref260438">Glaciation</a><ul class="list-unstyled" data-level="h3"><li data-target="#ref260439"><a class="w-100 link-gray-900" href="/science/Quaternary/The-Quaternary-environment#ref260439">The “Ice Ages”</a></li></ul><ul class="list-unstyled" data-level="h3"><li data-target="#ref260440" class="has-children"><a class="w-100 link-gray-900" href="/science/Quaternary/The-Quaternary-environment#ref260440">Glacial remnants</a><ul class="list-unstyled" data-level="h4"><li data-target="#ref260441"><a class="w-100 link-gray-900" href="/science/Quaternary/The-Quaternary-environment#ref260441">Landforms</a></li></ul><ul class="list-unstyled" data-level="h4"><li data-target="#ref260442"><a class="w-100 link-gray-900" href="/science/Quaternary/The-Quaternary-environment#ref260442">Lakes</a></li></ul></li></ul></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref260443"><a class="w-100 link-gray-900" href="/science/Quaternary/Sea-level-changes">Sea-level changes</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref260444"><a class="w-100 link-gray-900" href="/science/Quaternary/Sea-level-changes#ref260444">Paleoclimate</a></li></ul></div></li><li data-target="#ref260445"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/Quaternary/Quaternary-life">Quaternary life</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref260446"><a class="w-100 link-gray-900" href="/science/Quaternary/Quaternary-life#ref260446">Fauna and flora</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref260447"><a class="w-100 link-gray-900" href="/science/Quaternary/Hominin-evolution">Hominin evolution</a></li></ul></div></li><li data-target="#ref260448"><div class="d-flex align-items-center"><button class="h1-link-drawer-button btn btn-xs btn-circle d-flex rounded" type="button" aria-label="Toggle Heading"><em class="material-icons font-18" data-icon="keyboard_arrow_right"></em></button><a class="w-100 link-gray-900" href="/science/Quaternary/Hominin-evolution#ref260448">Quaternary geology</a></div><div class="ml-40 toc-drawer sub-toc-drawer"><ul class="list-unstyled" data-level="h2"><li data-target="#ref260449"><a class="w-100 link-gray-900" href="/science/Quaternary/Hominin-evolution#ref260449">Economic significance of Quaternary deposits</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref260450"><a class="w-100 link-gray-900" href="/science/Quaternary/Types-of-Quaternary-sediments">Types of Quaternary sediments</a></li></ul><ul class="list-unstyled" data-level="h2"><li data-target="#ref260451"><a class="w-100 link-gray-900" href="/science/Quaternary/Types-of-Quaternary-sediments#ref260451">Correlation of Quaternary deposits</a></li></ul></div></li></ul> <a class="toc-extra-link link-gray-900" href="https://www.britannica.com/science/Quaternary/additional-info">References & Edit History</a> <a class="toc-extra-link link-gray-900" href="/facts/Quaternary">Quick Facts & Related Topics</a> </div> <div class="tlr-media-slider pb-10 mb-30"> <a class="section-header link-gray-900 font-serif font-14 font-weight-bold mb-10 mx-10" href="https://www.britannica.com/science/Quaternary/images-videos">Images</a> <div class="slider js-slider position-relative d-inline-flex align-items-center mw-100 "> <div class="slider-container js-slider-container overflow-hidden d-flex overflow-hidden text-nowrap ml-15"> <a href="https://cdn.britannica.com/50/136150-050-BC0EEAA7/Distribution-landmasses-regions-seas-ocean-basins-locations.jpg" data-href="/media/1/486563/146757" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/50/136150-004-16E00D1B/Distribution-landmasses-regions-seas-ocean-basins-locations.jpg" alt="Quaternary paleogeography" height="50" /> </a> <a href="https://cdn.britannica.com/67/73167-050-C66534D1/chart.jpg" data-href="/media/1/486563/66800" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/67/73167-004-106002DC/chart.jpg" alt="geologic time" height="50" /> </a> <a href="https://cdn.britannica.com/79/131679-050-CC5EBAB3/Quaternary-Period-subdivisions.jpg" data-href="/media/1/486563/157631" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/79/131679-004-5342B8F8/Quaternary-Period-subdivisions.jpg" alt="Quaternary Period in geologic time" height="50" /> </a> <a href="https://cdn.britannica.com/32/75732-050-8B294308/Matterhorn-Alpine-valley.jpg" data-href="/media/1/486563/75099" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/32/75732-004-5A472A67/Matterhorn-Alpine-valley.jpg" alt="Matterhorn" height="50" /> </a> <a href="https://cdn.britannica.com/78/37678-004-4490408F/moraine-Gornergletscher-Pennine-Alps-Switz-Zermatt.jpg" data-href="/media/1/486563/30249" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/78/37678-004-4490408F/moraine-Gornergletscher-Pennine-Alps-Switz-Zermatt.jpg" alt="Gornergletscher (Gorner Glacier" height="50" /> </a> <a href="https://cdn.britannica.com/53/3053-050-EA4F2FBA/esker-ridge-gravel-glacier-sand-winds-Thelon.jpg" data-href="/media/1/486563/2623" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/53/3053-004-981AE21B/esker-ridge-gravel-glacier-sand-winds-Thelon.jpg" alt="esker: Nunavut" height="50" /> </a> <a href="https://cdn.britannica.com/09/74609-050-21E14E52/Wooly-mammoth-replica-species-Canadian-extinct.jpg" data-href="/media/1/486563/73085" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/09/74609-159-5F6CDC37/Wooly-mammoth-replica-species-Canadian-extinct.jpg" alt="woolly mammoth (Mammuthus primigenius)" height="50" /> </a> <a href="https://cdn.britannica.com/58/41258-004-F83472D2/rhinoceros.jpg" data-href="/media/1/486563/33829" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/58/41258-004-F83472D2/rhinoceros.jpg" alt="woolly rhinoceros" height="50" /> </a> <a href="https://cdn.britannica.com/10/12310-004-384CF25F/wolf-detail-mural-Rancho-La-Brea-Calif-1922.jpg" data-href="/media/1/486563/5233" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/10/12310-004-384CF25F/wolf-detail-mural-Rancho-La-Brea-Calif-1922.jpg" alt="dire wolf" height="50" /> </a> <a href="https://cdn.britannica.com/92/392-050-14244BE2/scheme-evolution-human-lineage-hominin-species-bars.jpg" data-href="/media/1/486563/45440" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/92/392-004-32E989F5/scheme-evolution-human-lineage-hominin-species-bars.jpg" alt="human evolutionary pathways" 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Please refer to the appropriate style manual or other sources if you have any questions. </div> <div class="label mt-20 mb-10">Select Citation Style</div> <select class="js-citation-format-select form-select"> <option selected value="mla">MLA</option> <option value="apa">APA</option> <option value="chicago">Chicago Manual of Style</option> </select> <div class="citation font-serif border rounded p-15 mt-20" data-authors="Belknap, Daniel F." data-authors-initial="Belknap, D.F." data-title="Quaternary" data-published-date="19 Feb. 2025" data-url="https://www.britannica.com/science/Quaternary" > <div class="citation-text"></div> </div> <button class="js-copy-citation-button mt-20 btn btn-xs btn-outline-blue border shadow-sm pr-10" > <em class="material-icons md-icon ml-n10 my-n5 mr-5" data-icon="file_copy"></em> <span class="js-citation-status-text">Copy Citation</span> </button> </div> </div> </div> <div> <button class="js-share-modal-button js-modal btn btn-sm btn-link gtm-topic-tool font-weight-bold btn-link" data-modal="[data-topic-id=486563] .md-share-modal"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="share"></em> Share </button> <div class="md-share-modal size-lg d-none qa-share-modal"> <div class="md-modal-body"> <div class="h2 font-serif d-flex align-items-center pb-15 border-bottom"> <em class="material-icons text-blue mr-10" data-icon="share"></em> Share </div> <div class="label my-20">Share to social media</div> <div class="md-social-toolbar-circle d-flex align-items-start inverted" data-value="share" title="Quaternary" data-url="https://www.britannica.com/science/Quaternary" > <a class="social-icon facebook justify-content-center d-flex align-items-center align-self-center" data-provider="facebook" href="https://www.facebook.com/BRITANNICA/" target="_blank" rel="noopener"><span>Facebook</span></a> <a class="social-icon x justify-content-center d-flex align-items-center align-self-center" data-provider="x" href="https://x.com/britannica" target="_blank" rel="noopener"><span>X</span></a> </div> <div class="label pt-20 mt-20 mb-5 border-top">URL</div> <a class="font-serif text-truncate d-inline-block" href="https://www.britannica.com/science/Quaternary">https://www.britannica.com/science/Quaternary</a> </div> </div> </div> <div> <button class="js-feedback-modal-button js-modal btn btn-sm btn-link gtm-topic-tool font-weight-bold btn-link" data-modal=".md-feedback-modal"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="message"></em> Feedback </button> </div> <div> <button class="qa-external-website-modal-button js-modal btn btn-sm btn-link gtm-topic-tool font-weight-bold btn-link" data-modal="[data-topic-id=486563] .md-websites-modal"> <em class="material-icons md-icon ml-n10 mr-5" data-icon="link"></em> External Websites </button> </div> </div> <div class="md-feedback-modal size-lg d-none"> <div class="md-modal-body"> <div class="h2 font-serif pb-15 border-bottom"> Feedback </div> <form method="post" action="/submission/feedback/486563"> <div class="my-20"> Corrections? 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Let us know if you have suggestions to improve this article (requires login). </div> <div class="type-menu"> <label for="feedback-type" class="label mb-10">Feedback Type</label> <select id="feedback-type" class="form-select mb-30" name="feedbackTypeId" required> <option value="" selected="selected">Select a type (Required)</option> <option value="1">Factual Correction</option> <option value="2">Spelling/Grammar Correction</option> <option value="3">Link Correction</option> <option value="4">Additional Information</option> <option value="5">Other</option> </select> </div> <label for="feedback" class="label mb-10">Your Feedback</label> <textarea id="feedback" class="form-control mb-30" name="feedback" maxlength="3000" rows="7" required></textarea> <button class="btn btn-blue" type="submit">Submit Feedback</button> </form> <div class="success-messaging d-none mt-30"> <div class="title">Thank you for your feedback</div> <p>Our editors will review what you’ve submitted and determine whether to revise the article.</p> </div> </div> </div> <div class="md-websites-modal size-lg d-none"> <div class="md-modal-body"> <div class="h2 font-serif pb-15 border-bottom font-weight-bold"> External Websites </div> <div class="pb-20"> <ul class="list-unstyled mt-20 lh-lg"> <li><a class="external" href="https://www.academia.edu/94578774/The_Quaternary_System_Period_current_status_and_future_challenges" target="_blank" rel="noopener ">Academia - The Quaternary System/Period: current status and future challenges (PDF)</a></li> <li><a class="external" href="https://cteco.uconn.edu/guides/resource/CT_ECO_Resource_Guide_Quaternary_Geology.pdf" target="_blank" rel="noopener ">University of Connecticut - Department of Energy and Environmental Protection - Quaternary Geology</a></li> <li><a class="external" href="https://www.livescience.com/43151-quaternary-period.html" target="_blank" rel="noopener ">LiveScience - Quaternary Period: Climate, Animals and Other Facts</a></li> <li><a class="external" href="https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=a85626c718534ca8b6b45a04dc9e28e5f2aba04d" target="_blank" rel="noopener ">CiteSeerX - Time Constraints and Tie-Points in the Quaternary Period</a></li> <li><a class="external" href="https://ijarsct.co.in/Paper2237.pdf" target="_blank" rel="noopener ">International Journal of Advanced Research in Science, Communication and Technology - Quaternary Changes in the Indian Subcontinent: Implications on Neotectonics</a></li> </ul> </div> </div> </div> </div> </div> <div class="toc-header-marker"></div> <button class="ai-ask-button btn btn-sm border-2 btn-outline-red-400 border-red-400 d-none mr-0 mr-lg-10 ml-5 ml-sm-10 ml-lg-0 p-10 px-sm-5 px-md-10 js-header-ai-ask-button"> Ask the Chatbot a Question </button> <div class="caption alternate-titles">Also known as: Great Ice Age, Quaternary Period</div> <div class="md-byline module-spacing "> <div class="font-serif font-12"> <span class="written-by text-gray-700"> Written by </span> <div class="editor-popover popover p-0"> <a class="d-block p-20 qa-editor-popup gtm-byline font-12 byline-contributor" href="/contributor/Daniel-F-Belknap/5343" > <div class="editor-title font-16 font-weight-bold">Daniel F. Belknap</div> <div class="editor-description font-12 font-serif mt-5 clamp-description text-black">Professor of Geological Sciences, Marine Studies, and Quaternary Studies, University of Maine, U.S.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link gtm-byline font-12 byline-contributor text-decoration-underline"> Daniel F. Belknap</span></div> <div class="font-serif font-12 text-gray-700"> <span class="qa-fact-checked-by">Fact-checked by</span> <div class="editor-popover popover p-0"> <a class="d-block p-20 qa-editor-popup font-12" href="/editor/The-Editors-of-Encyclopaedia-Britannica/4419" > <div class="editor-title font-16 font-weight-bold">The Editors of Encyclopaedia Britannica</div> <div class="editor-description font-12 font-serif mt-5 text-black">Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. They write new content and verify and edit content received from contributors.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link font-12 "> The Editors of Encyclopaedia Britannica</span></div> <div class="last-updated font-12 font-serif"> <span class="text-gray-700"> Last Updated: <time datetime="2025-02-19T00:00:00CST" >Feb 19, 2025</time> •</span> <a class="byline-edit-history" href="https://www.britannica.com/science/Quaternary/additional-info#history" rel="nofollow">Article History</a> </div></div> </div> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button d-none d-sm-block js-sections-inline-button module-spacing btn d-lg-none"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <div class="d-flex d-sm-none flex-row"> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button js-sections-inline-button module-spacing"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <button class="ai-ask-button btn btn-sm border-2 btn-outline-red-400 border-red-400 module-spacing js-inline-ai-ask-button p-10 ml-5"> Ask the Chatbot </button> </div> <div class="js-qf-module qf-module px-40 px-sm-20 py-15 mx-auto module-spacing font-14 bg-gray-50 rounded"> <div class="facts-list mt-10"> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Key People: </dt> <dd><a href="/biography/Maurice-Irenee-Marie-Gignoux" topicid="233462">Maurice-Irénée-Marie Gignoux</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Related Topics: </dt> <dd><a href="/science/Pleistocene-Epoch" topicid="464579">Pleistocene Epoch</a></dd> <dd><a href="/science/Holocene-Epoch" topicid="269574">Holocene Epoch</a></dd> <dd><a href="/science/Anthropocene-Epoch" topicid="1492578">Anthropocene Epoch</a></dd> <dd><a href="/topic/Meghalayan-stage" topicid="2134758">Meghalayan Stage</a></dd> <dd><a href="/topic/Northgrippian-stage" topicid="2134756">Northgrippian stage</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>On the Web: </dt> <dd><a href="https://www.academia.edu/94578774/The_Quaternary_System_Period_current_status_and_future_challenges" target="_blank">Academia - The Quaternary System/Period: current status and future challenges (PDF)</a> (Feb. 19, 2025)</dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> <div class="text-center"> <a class="btn btn-sm btn-link p-0" href="/facts/Quaternary"> See all related content </a> </div> </div> </div> </div><span class="marker before-article"></span><section data-level="1" id="ref1"><span class="marker PREMOD1 mod-inline"></span><p class="topic-paragraph"><strong><span id="ref921936"></span>Quaternary</strong>, in the <a href="https://www.britannica.com/science/geology" class="md-crosslink " data-show-preview="true">geologic</a> history of <a href="https://www.britannica.com/place/Earth" class="md-crosslink " data-show-preview="true">Earth</a>, a unit of time within the <a href="https://www.britannica.com/science/Cenozoic-Era" class="md-crosslink " data-show-preview="true">Cenozoic Era</a>, beginning 2,588,000 years ago and continuing to the present day. The Quaternary has been characterized by several periods of glaciation (the “<a href="https://www.britannica.com/science/ice-age-geology" class="md-crosslink " data-show-preview="true">ice ages</a>” of common lore), when ice sheets many kilometres thick have covered vast areas of the <span id="ref922048"></span><a href="https://www.britannica.com/science/continent" class="md-crosslink " data-show-preview="true">continents</a> in temperate areas. During and between these glacial periods, rapid changes in <a href="https://www.britannica.com/science/climate-meteorology" class="md-crosslink " data-show-preview="true">climate</a> and <a href="https://www.britannica.com/science/sea-level" class="md-crosslink " data-show-preview="true">sea level</a> have occurred, and <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="environments" href="https://www.merriam-webster.com/dictionary/environments" data-type="MW">environments</a> worldwide have been altered. These variations in turn have driven rapid changes in life-forms, both <a href="https://www.britannica.com/topic/Flora-Roman-mythology" class="md-crosslink " data-show-preview="true">flora</a> and <a href="https://www.britannica.com/topic/Fauna-Roman-goddess" class="md-crosslink " data-show-preview="true">fauna</a>. Beginning some 200,000 years ago, they were responsible for the rise of modern <a href="https://www.britannica.com/topic/human-being" class="md-crosslink " data-show-preview="true">humans</a>.</p><span class="marker MOD1 mod-inline"></span><span class="marker PREMOD2 mod-inline"></span><div class="assemblies"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="66800" data-asm-type="image"><div class="md-assembly-wrapper card-media" data-type="image"><a href="https://cdn.britannica.com/67/73167-050-C66534D1/chart.jpg" class="gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media" data-href="/media/1/486563/66800"><picture><source media="(min-width: 680px)" srcset="https://cdn.britannica.com/67/73167-050-C66534D1/chart.jpg"><img src="https://cdn.britannica.com/67/73167-050-C66534D1/chart.jpg?w=300" alt="geologic time" data-width="2000" data-height="1500" loading="eager"></picture><button class="magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10" aria-label="Zoom in"><em class="material-icons link-blue" data-icon="zoom_in"></em></button></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><a class="gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link" href="https://cdn.britannica.com/67/73167-050-C66534D1/chart.jpg" data-href="/media/1/486563/66800">geologic time</a><span>The stratigraphic chart of geologic time.</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div></figcaption></figure></div></div><p class="topic-paragraph">The Quaternary is one of the best-studied parts of the geologic record. In part this is because it is well preserved in comparison with the other periods of <a href="https://www.britannica.com/science/geologic-time" class="md-crosslink autoxref " data-show-preview="true">geologic time</a>. Less of it has been lost to erosion, and the sediments are not usually altered by rock-forming processes. Quaternary rocks and sediments, being the most recently laid geologic strata, can be found at or near the surface of the Earth in valleys and on plains, seashores, and even the seafloor. These deposits are important for <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="unraveling" href="https://www.britannica.com/dictionary/unraveling" data-type="EB">unraveling</a> geologic history because they are most easily compared to modern sedimentary deposits. The environments and geologic processes earlier in the period were similar to those of today; a large proportion of Quaternary <span id="ref921991"></span><a href="https://www.britannica.com/science/fossil" class="md-crosslink " data-show-preview="true">fossils</a> are related to living organisms; and numerous <a href="https://www.britannica.com/science/dating-geochronology" class="md-crosslink autoxref " data-show-preview="true">dating</a> techniques can be used to provide relatively precise timing of events and rates of change.</p><span class="marker MOD2 mod-inline"></span><span class="marker PREMOD3 mod-inline"></span><p class="topic-paragraph">The term Quaternary originated early in the 19th century when it was applied to the youngest deposits in the <a href="https://www.britannica.com/place/Paris-Basin" class="md-crosslink " data-show-preview="true">Paris Basin</a> in <a href="https://www.britannica.com/place/France" class="md-crosslink " data-show-preview="true">France</a> by French geologist <span id="ref921941"></span><a href="https://www.britannica.com/biography/Jules-Desnoyers" class="md-crosslink ">Jules Desnoyers</a>, who followed an antiquated method of referring to geologic eras as “Primary,” “Secondary,” “<a href="https://www.britannica.com/science/Tertiary-Period" class="md-crosslink " data-show-preview="true">Tertiary</a>,” and so on. Beginning with the work of Scottish geologist <span id="ref921942"></span><a href="https://www.britannica.com/biography/Charles-Lyell" class="md-crosslink " data-show-preview="true">Charles Lyell</a> in the 1830s, the Quaternary Period was divided into two <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="epochs" href="https://www.britannica.com/dictionary/epochs" data-type="EB">epochs</a>, the <a href="https://www.britannica.com/science/Pleistocene-Epoch" class="md-crosslink " data-show-preview="true">Pleistocene</a> and the <a href="https://www.britannica.com/science/Holocene-Epoch" class="md-crosslink " data-show-preview="true">Holocene</a>, with the Pleistocene (and therefore the Quaternary) understood to have begun some 1.8 million years ago. In 1948 a decision was made at the 18th <span id="ref921943"></span>International Geological Congress (IGC) in London that the base of the <a href="https://www.britannica.com/science/Pleistocene-Series" class="md-crosslink autoxref " data-show-preview="true">Pleistocene Series</a> should be fixed in marine rocks exposed in the coastal areas of Calabria in southern <a href="https://www.britannica.com/place/Italy" class="md-crosslink autoxref " data-show-preview="true">Italy</a>. As ratified by the <span id="ref921944"></span><a href="https://www.britannica.com/topic/International-Commission-on-Stratigraphy" class="md-crosslink ">International Commission on Stratigraphy</a> (ICS) in 1985, the type section for boundary between the Pleistocene and the earlier Pliocene occurs in a sequence of 1.8-million-year-old marine strata at Vrica in <a href="https://www.britannica.com/place/Calabria-ancient-city-Italy" class="md-crosslink " data-show-preview="true">Calabria</a>. However, no decision was made to equate the beginning of the Pleistocene <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="Epoch" href="https://www.britannica.com/dictionary/Epoch" data-type="EB">Epoch</a> to the beginning of the Quaternary Period, and indeed the very status of the Quaternary as a period within the geologic time scale had come into question. Various gatherings of the IGC in the 19th and 20th centuries had agreed to retain both the Tertiary and Quaternary as useful time units, particularly for climatic- and continent-based studies, but a growing number of geologists came to favour dividing the Cenozoic Era into two other periods, the <a href="https://www.britannica.com/science/Paleogene-Period" class="md-crosslink " data-show-preview="true">Paleogene</a> and the <a href="https://www.britannica.com/science/Neogene-Period" class="md-crosslink " data-show-preview="true">Neogene</a>. In 2005 the ICS decided to recommend keeping the Tertiary and Quaternary in the time scale, but only as informal sub-eras of the Cenozoic.</p><div class="one-good-fact-module"> </div><span class="marker MOD3 mod-inline"></span><span class="marker PREMOD4 mod-inline"></span><div class="assemblies"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="157631" data-asm-type="image"><div class="md-assembly-wrapper card-media" data-type="image"><a href="https://cdn.britannica.com/79/131679-050-CC5EBAB3/Quaternary-Period-subdivisions.jpg" class="gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media" data-href="/media/1/486563/157631"><picture><source media="(min-width: 680px)" srcset="https://cdn.britannica.com/79/131679-050-CC5EBAB3/Quaternary-Period-subdivisions.jpg"><img src="https://cdn.britannica.com/79/131679-050-CC5EBAB3/Quaternary-Period-subdivisions.jpg?w=300" alt="Quaternary Period in geologic time" data-width="970" data-height="1600" loading="eager"></picture><button class="magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10" aria-label="Zoom in"><em class="material-icons link-blue" data-icon="zoom_in"></em></button></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><a class="gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link" href="https://cdn.britannica.com/79/131679-050-CC5EBAB3/Quaternary-Period-subdivisions.jpg" data-href="/media/1/486563/157631">Quaternary Period in geologic time</a><span>The Quaternary Period and its subdivisions.</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div></figcaption></figure></div></div><p class="topic-paragraph">The ICS abandoned the sub-era structure in 2008, deciding instead to formally <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="designate" href="https://www.britannica.com/dictionary/designate" data-type="EB">designate</a> the Quaternary as the uppermost period of the Cenozoic Era, following the aforementioned Paleogene and Neogene periods. In 2009 the <span id="ref1047289"></span><a href="https://www.britannica.com/topic/International-Union-of-Geological-Sciences" class="md-crosslink ">International Union of Geological Sciences</a> (IUGS) officially ratified the decision to set the beginning of the Quaternary at 2,588,000 years ago, a time when <a href="https://www.britannica.com/science/rock-geology" class="md-crosslink autoxref " data-show-preview="true">rock</a> strata show extensive evidence of widespread expansion of ice sheets over the northern continents and the beginning of an <a href="https://www.britannica.com/science/era-geologic-time" class="md-crosslink autoxref " data-show-preview="true">era</a> of dramatic climatic and oceanographic change. This time is coincident with the beginning of the Gelasian Age, which was officially designated by the IUGS and the ICS in 2009 as the lowermost stage of the Pleistocene Epoch. The type section for the <span id="ref1047290"></span><a href="https://www.britannica.com/science/Gelasian-Stage" class="md-crosslink " data-show-preview="true">Gelasian Stage</a>, the rock layer laid down during the Gelasian Age, is found at Monte San Nicola near Gela, Sicily.</p><span class="marker MOD4 mod-inline"></span></section> <span class="marker end-of-content"></span><span class="marker after-article"></span></div> <div id="chatbot-simplify-root"></div> <div id="chatbot-root"></div> </div> </div> </div> <div class="ai-dialog-placeholder"></div> </div> </div> <aside class="col-md-da-320"></aside> </div> </div> </div> </div> </article> </div> </div> </div> </div> </main> <div id="md-footer"></div> <noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-5W6NC8" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript> <script type="text/javascript" id="_informizely_script_tag"> var IzWidget = IzWidget || {}; (function (d) { var scriptElement = d.createElement('script'); scriptElement.type = 'text/javascript'; scriptElement.async = true; scriptElement.src = "https://insitez.blob.core.windows.net/site/f780f33e-a610-4ac2-af81-3eb184037547.js"; var node = d.getElementById('_informizely_script_tag'); node.parentNode.insertBefore(scriptElement, node); } )(document); </script>  <script> window.ap3c = window.ap3c || {}; var ap3c = window.ap3c; ap3c.cmd = ap3c.cmd || []; ap3c.cmd.push(function() { ap3c.init('ZO4siT4cLwnykPnzZWJtd3Byb2Q', 'https://engage.email.britannica.com/'); ap3c.track({v: 0}); }); ap3c.activity = function(act) { ap3c.act = (ap3c.act || []); ap3c.act.push(act); }; var s, t; s = document.createElement('script'); s.type = 'text/javascript'; s.src = "https://engage.email.britannica.com/app.js"; t = document.getElementsByTagName('script')[0]; t.parentNode.insertBefore(s, t); </script> <script class="marketing-page-info" type="application/json"> {"pageType":"Topic","templateName":"DESKTOP","pageNumber":1,"pagesTotal":6,"pageId":486563,"pageLength":694,"initialLoad":true,"lastPageOfScroll":false} </script> <script class="marketing-content-info" type="application/json"> [] </script> <script src="https://cdn.britannica.com/mendel-resources/3-133/js/libs/jquery-3.5.0.min.js?v=3.133.36"></script> <script type="text/javascript" data-type="Init Mendel Code Splitting"> (function() { $.ajax({ dataType: 'script', cache: true, url: 'https://cdn.britannica.com/mendel-resources/3-133/dist/topic-page.js?v=3.133.36' }); })(); </script> <script class="analytics-metadata" type="application/json"> {"leg":"D","adLeg":"D","userType":"ANONYMOUS","pageType":"Topic","pageSubtype":null,"articleTemplateType":"PAGINATED","gisted":false,"pageNumber":1,"hasSummarizeButton":false,"hasAskButton":true} </script> <script type="text/javascript"> EBStat={accountId:-1,hostnameOverride:'webstats.eb.com',domain:'www.britannica.com', json:''}; </script> <script type="text/javascript"> ( function() { $.ajax( { dataType: 'script', cache: true, url: '//www.britannica.com/webstats/mendelstats.js?v=1' } ) .done( function() { try {writeStat(null,EBStat);} catch(err){} } ); })(); </script> <div id="bc-fixed-dialogue"></div> </body> </html>

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Quaternary | Definition, Period, Climate, Animals, Plants, Timeline, & Facts | Britannica