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class="vector-sitenotice-container"> <div id="siteNotice"></div> </div> <div class="vector-column-start"> <div class="vector-main-menu-container"> <div id="mw-navigation"> <nav id="mw-panel" class="vector-main-menu-landmark" aria-label="Site"> <div id="vector-main-menu-pinned-container" class="vector-pinned-container"> </div> </nav> </div> </div> <div class="vector-sticky-pinned-container"> <nav id="mw-panel-toc" aria-label="Contents" data-event-name="ui.sidebar-toc" class="mw-table-of-contents-container vector-toc-landmark"> <div id="vector-toc-pinned-container" class="vector-pinned-container"> <div id="vector-toc" class="vector-toc vector-pinnable-element"> <div class="vector-pinnable-header vector-toc-pinnable-header vector-pinnable-header-pinned" data-feature-name="toc-pinned" data-pinnable-element-id="vector-toc" > <h2 class="vector-pinnable-header-label">Contents</h2> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" 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-Description_and_name_origin" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Description_and_name_origin"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>Description and name origin</span> </div> </a> <ul id="toc-Description_and_name_origin-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Hesperian_chronology_and_stratigraphy" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Hesperian_chronology_and_stratigraphy"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Hesperian chronology and stratigraphy</span> </div> </a> <button aria-controls="toc-Hesperian_chronology_and_stratigraphy-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 Hesperian chronology and stratigraphy subsection</span> </button> <ul id="toc-Hesperian_chronology_and_stratigraphy-sublist" class="vector-toc-list"> <li id="toc-System_vs._period" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#System_vs._period"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.1</span> <span>System vs. period</span> </div> </a> <ul id="toc-System_vs._period-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Boundaries_and_subdivisions" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Boundaries_and_subdivisions"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.2</span> <span>Boundaries and subdivisions</span> </div> </a> <ul id="toc-Boundaries_and_subdivisions-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Mars_during_the_Hesperian_Period" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Mars_during_the_Hesperian_Period"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Mars during the Hesperian Period</span> </div> </a> <button aria-controls="toc-Mars_during_the_Hesperian_Period-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 Mars during the Hesperian Period subsection</span> </button> <ul id="toc-Mars_during_the_Hesperian_Period-sublist" class="vector-toc-list"> <li id="toc-Impact_cratering" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Impact_cratering"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Impact cratering</span> </div> </a> <ul id="toc-Impact_cratering-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Notes_and_references" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Notes_and_references"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Notes and references</span> </div> </a> <ul id="toc-Notes_and_references-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Bibliography_and_recommended_reading" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Bibliography_and_recommended_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Bibliography and recommended reading</span> </div> </a> <ul id="toc-Bibliography_and_recommended_reading-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" title="Table of Contents" > <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 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href="https://eo.wikipedia.org/wiki/Hesperia_epoko" title="Hesperia epoko – Esperanto" lang="eo" hreflang="eo" data-title="Hesperia epoko" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Hesp%C3%A9rien" title="Hespérien – French" lang="fr" hreflang="fr" data-title="Hespérien" 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/Hesperium" title="Hesperium – Indonesian" lang="id" hreflang="id" data-title="Hesperium" 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-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Esperiano" title="Esperiano – Italian" lang="it" hreflang="it" data-title="Esperiano" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-la mw-list-item"><a href="https://la.wikipedia.org/wiki/Hesperium" title="Hesperium – Latin" lang="la" hreflang="la" data-title="Hesperium" data-language-autonym="Latina" data-language-local-name="Latin" class="interlanguage-link-target"><span>Latina</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Hesperium" title="Hesperium – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="Hesperium" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Okres_hesperyjski" title="Okres hesperyjski – Polish" lang="pl" hreflang="pl" data-title="Okres hesperyjski" 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/Hesperiano" title="Hesperiano – Portuguese" lang="pt" hreflang="pt" data-title="Hesperiano" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%93%D0%B5%D1%81%D0%BF%D0%B5%D1%80%D0%B8%D0%B9%D1%81%D0%BA%D0%B8%D0%B9_%D0%BF%D0%B5%D1%80%D0%B8%D0%BE%D0%B4" title="Гесперийский период – Russian" lang="ru" hreflang="ru" data-title="Гесперийский период" data-language-autonym="Русский" data-language-local-name="Russian" 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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">This article is about the Mars geologic system and time period. For other senses, see <a href="/wiki/Hesperia_(disambiguation)" class="mw-redirect mw-disambig" title="Hesperia (disambiguation)">Hesperia</a>.</div> <style data-mw-deduplicate="TemplateStyles:r1257001546">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-full-data:not(.notheme) div:not(.notheme){background:#1f1f23!important;color:#f8f9fa}}@media(min-width:640px){body.skin--responsive .mw-parser-output .infobox-table{display:table!important}body.skin--responsive .mw-parser-output .infobox-table>caption{display:table-caption!important}body.skin--responsive .mw-parser-output .infobox-table>tbody{display:table-row-group}body.skin--responsive .mw-parser-output .infobox-table tr{display:table-row!important}body.skin--responsive .mw-parser-output .infobox-table th,body.skin--responsive .mw-parser-output .infobox-table td{padding-left:inherit;padding-right:inherit}}</style><table class="infobox" style="width:23em;"><tbody><tr><th colspan="2" class="infobox-above" style="padding:0.25em 0.33em 0.33em;line-height:1.2em;font-size:1.25em;background:rgb(255.0, 51.0, 51.0);">Hesperian</th></tr><tr><td colspan="2" class="infobox-subheader"><div class="noprint"><span style="display:inline-block;"></span><span style="display:inline-block;">3700 – 3000 <a href="/wiki/Year#SI_prefix_multipliers" title="Year">Ma</a></span> <span style="display:inline-block;">(upper bound uncertain – between about 3200 and 2000 million years ago)</span><div id="Timeline-row" style="margin: 4px auto 0; clear:both; width:250px; padding:0px; height:18px; overflow:visible; border:1px #666; border-style:solid none; font-size:small; position:relative; z-index:0;"> <div style="position:absolute; height:18px; text-align:center; background-color:rgb(178.0, 102.0, 255.0); left:0px; width:23.880432384734px;"><a href="/wiki/Noachian" title="Noachian">PreN</a></div> <div style="position:absolute; height:18px; text-align:center; background-color:rgb(127.0, 127.0, 204.0); left:23.880432384734px; width:22.060445621002px;"><a href="/wiki/Noachian" title="Noachian">N</a></div> <div style="position:absolute; height:18px; text-align:center; background-color:rgb(255.0, 51.0, 51.0); left:45.940878005736px; width:38.605779836753px;"><a class="mw-selflink selflink">H</a></div> <div style="position:absolute; height:18px; text-align:center; background-color:rgb(255.0, 127.0, 51.0); left:84.546657842488px; width:165.45334215751px;"><a href="/wiki/Amazonian_(Mars)" title="Amazonian (Mars)">A</a></div> <div id="end-border" style="position:absolute; height:100%; background-color:#666; width:1px; left:249px"></div><div style="margin:0 auto; line-height:0; clear:both; width:250px; padding:0px; height:8px; overflow:visible; background-color:transparent; position:relative; top:-4px; z-index:100;"><div style="position:absolute; height:8px; left:45.940878005736px; width:93.756893889257px; background-color:#360; opacity:0.42;"></div> <div style="position:absolute; height:8px; left:45.940878005736px; width:38.605779836753px; background-color:#360; opacity:1;"></div> <div style="position:absolute; height:6px; top:1px; left:46.940878005736px; width:36.605779836753px; background-color:#6c3;"></div> </div> </div></div></td></tr><tr><td colspan="2" class="infobox-image"><span typeof="mw:File"><a href="/wiki/File:Hesperia_Planum.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/74/Hesperia_Planum.jpg/250px-Hesperia_Planum.jpg" decoding="async" width="250" height="250" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/74/Hesperia_Planum.jpg/375px-Hesperia_Planum.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/74/Hesperia_Planum.jpg/500px-Hesperia_Planum.jpg 2x" data-file-width="791" data-file-height="791" /></a></span><div class="infobox-caption"><a href="/wiki/Mars_Orbital_Laser_Altimeter" class="mw-redirect" title="Mars Orbital Laser Altimeter">MOLA</a> colorized relief map of <a href="/wiki/Hesperia_Planum" title="Hesperia Planum">Hesperia Planum</a>, the <a href="/wiki/Type_locality_(geology)" title="Type locality (geology)">type area</a> for the Hesperian System. Note that Hesperia Planum has fewer large impact craters than the surrounding <a href="/wiki/Noachian_(Mars)" class="mw-redirect" title="Noachian (Mars)">Noachian</a> terrain, indicating a younger age. Colors indicate elevation, with red highest, yellow intermediate, and green/blue lowest.</div></td></tr><tr><th colspan="2" class="infobox-header" style="background:#ededed;">Chronology</th></tr><tr><th scope="row" class="infobox-label" style="width:10em;">Subdivisions</th><td class="infobox-data">Early Heperian<br /> Late Hesperian</td></tr><tr><th colspan="2" class="infobox-header" style="background:#ededed;">Usage information</th></tr><tr><th scope="row" class="infobox-label" style="width:10em;">Celestial body</th><td class="infobox-data"><a href="/wiki/Geological_history_of_Mars" title="Geological history of Mars">Mars</a></td></tr><tr><th scope="row" class="infobox-label" style="width:10em;">Time scale(s) used</th><td class="infobox-data">Martian Geologic Timescale</td></tr><tr><th colspan="2" class="infobox-header" style="background:#ededed;">Definition</th></tr><tr><th scope="row" class="infobox-label" style="width:10em;">Chronological unit</th><td class="infobox-data"><a href="/wiki/Geological_period" class="mw-redirect" title="Geological period">Period</a></td></tr><tr><th scope="row" class="infobox-label" style="width:10em;">Stratigraphic unit</th><td class="infobox-data"><a href="/wiki/System_(stratigraphy)" title="System (stratigraphy)">System</a></td></tr><tr><th scope="row" class="infobox-label" style="width:10em;">Type section</th><td class="infobox-data"><a href="/wiki/Hesperia_Planum" title="Hesperia Planum">Hesperia Planum</a></td></tr></tbody></table> <p>The <b>Hesperian</b> is a <a href="/wiki/System_(stratigraphy)" title="System (stratigraphy)">geologic system</a> and <a href="/wiki/Geologic_timescale" class="mw-redirect" title="Geologic timescale">time period</a> on the planet <a href="/wiki/Mars" title="Mars">Mars</a> characterized by widespread <a href="/wiki/Volcanology_of_Mars" class="mw-redirect" title="Volcanology of Mars">volcanic activity</a> and catastrophic flooding that carved immense <a href="/wiki/Outflow_channels" title="Outflow channels">outflow channels</a> across the surface. The Hesperian is an intermediate and transitional period of Martian history. During the Hesperian, Mars changed from the wetter and perhaps warmer world of the <a href="/wiki/Noachian_(Mars)" class="mw-redirect" title="Noachian (Mars)">Noachian</a> to the dry, cold, and dusty planet seen today.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> The <a href="/wiki/Absolute_age" class="mw-redirect" title="Absolute age">absolute age</a> of the Hesperian Period is uncertain. The beginning of the period followed the end of the <a href="/wiki/Late_Heavy_Bombardment" title="Late Heavy Bombardment">Late Heavy Bombardment</a><sup id="cite_ref-CarrHead10_2-0" class="reference"><a href="#cite_note-CarrHead10-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> and probably corresponds to the start of the lunar <a href="/wiki/Late_Imbrian" class="mw-redirect" title="Late Imbrian">Late Imbrian</a> period,<sup id="cite_ref-Tanaka86_3-0" class="reference"><a href="#cite_note-Tanaka86-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-HartmannNeukum_4-0" class="reference"><a href="#cite_note-HartmannNeukum-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> around 3700 million years ago (<a href="/wiki/Myr" class="mw-redirect" title="Myr">Mya</a>). The end of the Hesperian Period is much more uncertain and could range anywhere from 3200 to 2000 Mya,<sup id="cite_ref-Hartmann05_5-0" class="reference"><a href="#cite_note-Hartmann05-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> with 3000 Mya being frequently cited. The Hesperian Period is roughly coincident with the Earth's early <a href="/wiki/Archean" title="Archean">Archean</a> Eon.<sup id="cite_ref-CarrHead10_2-1" class="reference"><a href="#cite_note-CarrHead10-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>With the decline of heavy impacts at the end of the Noachian, <a href="/wiki/Volcanism" title="Volcanism">volcanism</a> became the primary geologic process on Mars, producing vast plains of <a href="/wiki/Flood_basalt" title="Flood basalt">flood basalts</a> and broad volcanic constructs (<a href="/wiki/Volcanism_on_Mars#Highland_Paterae" title="Volcanism on Mars">highland paterae</a>).<sup id="cite_ref-GreeleySpudis81_6-0" class="reference"><a href="#cite_note-GreeleySpudis81-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> By Hesperian times, all of the large <a href="/wiki/Shield_volcano" title="Shield volcano">shield volcanoes</a> on Mars, including <a href="/wiki/Olympus_Mons" title="Olympus Mons">Olympus Mons</a>, had begun to form.<sup id="cite_ref-Werner09_7-0" class="reference"><a href="#cite_note-Werner09-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> Volcanic outgassing released large amounts of <a href="/wiki/Sulfur_dioxide" title="Sulfur dioxide">sulfur dioxide</a> (SO<sub>2</sub>) and <a href="/wiki/Hydrogen_sulfide" title="Hydrogen sulfide">hydrogen sulfide</a> (H<sub>2</sub>S) into the atmosphere, causing a transition in the style of <a href="/wiki/Weathering" title="Weathering">weathering</a> from dominantly <a href="/wiki/Phyllosilicate" class="mw-redirect" title="Phyllosilicate">phyllosilicate</a> (<a href="/wiki/Clay" title="Clay">clay</a>) to <a href="/wiki/Sulfate" title="Sulfate">sulfate</a> <a href="/wiki/Mineralogy" title="Mineralogy">mineralogy</a>.<sup id="cite_ref-Bibring06_8-0" class="reference"><a href="#cite_note-Bibring06-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> Liquid water became more localized in extent and turned more acidic as it interacted with SO<sub>2</sub> and H<sub>2</sub>S to form <a href="/wiki/Sulfuric_acid" title="Sulfuric acid">sulfuric acid</a>.<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Barlow10_10-0" class="reference"><a href="#cite_note-Barlow10-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p><p>By the beginning of the Late Hesperian the atmosphere had probably thinned to its present density.<sup id="cite_ref-Barlow10_10-1" class="reference"><a href="#cite_note-Barlow10-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> As the planet cooled, <a href="/wiki/Groundwater" title="Groundwater">groundwater</a> stored in the upper crust (mega<a href="/wiki/Regolith" title="Regolith">regolith</a>) began to freeze, forming a thick <a href="/wiki/Cryosphere" title="Cryosphere">cryosphere</a> overlying a deeper zone of liquid water.<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> Subsequent volcanic or tectonic activity occasionally fractured the cryosphere, releasing enormous quantities of deep <a href="/wiki/Groundwater" title="Groundwater">groundwater</a> to the surface and carving huge <a href="/wiki/Outflow_channel" class="mw-redirect" title="Outflow channel">outflow channels</a>. Much of this water flowed into the northern hemisphere where it probably pooled to form large transient lakes or an ice covered ocean. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Description_and_name_origin">Description and name origin</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Hesperian&action=edit&section=1" title="Edit section: Description and name origin"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <i>Hesperian</i> System and Period is named after <a href="/wiki/Hesperia_Planum" title="Hesperia Planum">Hesperia Planum</a>, a moderately cratered highland region northeast of the <a href="/wiki/Hellas_Planitia" title="Hellas Planitia">Hellas</a> basin. The <a href="/wiki/Type_locality_(geology)" title="Type locality (geology)">type area</a> of the Hesperian System is in the <a href="/wiki/Mare_Tyrrhenum_quadrangle" title="Mare Tyrrhenum quadrangle">Mare Tyrrhenum quadrangle</a> (MC-22) around <span class="geo-inline"><style data-mw-deduplicate="TemplateStyles:r1156832818">.mw-parser-output .geo-default,.mw-parser-output .geo-dms,.mw-parser-output .geo-dec{display:inline}.mw-parser-output .geo-nondefault,.mw-parser-output .geo-multi-punct,.mw-parser-output .geo-inline-hidden{display:none}.mw-parser-output .longitude,.mw-parser-output .latitude{white-space:nowrap}</style><span class="plainlinks nourlexpansion"><a class="external text" href="https://geohack.toolforge.org/geohack.php?pagename=Hesperian&params=20_S_245_W_globe:Mars"><span class="geo-default"><span class="geo-dms" title="Maps, aerial photos, and other data for this location"><span class="latitude">20°S</span> <span class="longitude">245°W</span></span></span><span class="geo-multi-punct"> / </span><span class="geo-nondefault"><span class="geo-dec" title="Maps, aerial photos, and other data for this location">20°S 245°W</span><span style="display:none"> / <span class="geo">-20; -245</span></span></span></a></span></span>. The region consists of rolling, <a href="/wiki/Windstreak" title="Windstreak">wind-streaked</a> plains with abundant <a href="/wiki/Wrinkle_ridge" title="Wrinkle ridge">wrinkle ridges</a> resembling those on the <a href="/wiki/Lunar_maria" class="mw-redirect" title="Lunar maria">lunar maria</a>. These "ridged plains" are interpreted to be basaltic lava flows (<a href="/wiki/Flood_basalt" title="Flood basalt">flood basalts</a>) that erupted from fissures.<sup id="cite_ref-ScottCarr78_12-0" class="reference"><a href="#cite_note-ScottCarr78-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> The number-density of large impact craters is moderate, with about 125–200 craters greater than 5 km in diameter per million km<sup>2</sup>.<sup id="cite_ref-Tanaka86_3-1" class="reference"><a href="#cite_note-Tanaka86-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> Hesperian-aged ridged plains cover roughly 30% of the Martian surface;<sup id="cite_ref-CarrHead10_2-2" class="reference"><a href="#cite_note-CarrHead10-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> they are most prominent in Hesperia Planum, <a href="/wiki/Syrtis_Major_Planum" title="Syrtis Major Planum">Syrtis Major Planum</a>, Lunae Planum, Malea Planum, and the Syria-Solis-Sinai Plana in southern <a href="/wiki/Tharsis" title="Tharsis">Tharsis</a>.<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-GreeleyGuest87_15-0" class="reference"><a href="#cite_note-GreeleyGuest87-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> </p> <div class="timeline-wrapper"><map name="timeline_5zvezp5dhfrztp5iy4z56ceq8vii9on"><area shape="rect" href="/wiki/Pre%2DNoachian" coords="-4,9,98,30" title="Pre-Noachian" alt="Pre-Noachian" /><area shape="rect" href="/wiki/Noachian" coords="74,9,155,30" title="Noachian" alt="Noachian" /><area shape="rect" href="/wiki/Amazonian_(Mars)" coords="482,9,568,30" title="Amazonian (Mars)" alt="Amazonian (Mars)" /></map><img usemap="#timeline_5zvezp5dhfrztp5iy4z56ceq8vii9on" src="//upload.wikimedia.org/wikipedia/en/timeline/5zvezp5dhfrztp5iy4z56ceq8vii9on.png" /></div> <div class="center" style="width:auto; margin-left:auto; margin-right:auto;"><small><a href="/wiki/Geological_history_of_Mars" title="Geological history of Mars">Martian Time Periods (Millions of Years Ago)</a></small></div> <div class="mw-heading mw-heading2"><h2 id="Hesperian_chronology_and_stratigraphy">Hesperian chronology and stratigraphy</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Hesperian&action=edit&section=2" title="Edit section: Hesperian chronology and stratigraphy"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Mars_Cross_Section.tif" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/en/thumb/8/87/Mars_Cross_Section.tif/lossless-page1-340px-Mars_Cross_Section.tif.png" decoding="async" width="340" height="140" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/8/87/Mars_Cross_Section.tif/lossless-page1-510px-Mars_Cross_Section.tif.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/8/87/Mars_Cross_Section.tif/lossless-page1-680px-Mars_Cross_Section.tif.png 2x" data-file-width="369" data-file-height="152" /></a><figcaption>Schematic cross section of image at left. Surface units are interpreted as a sequence of layers (<a href="/wiki/Stratum" title="Stratum">strata</a>), with the youngest at top and oldest at bottom in accordance with the <a href="/wiki/Law_of_superposition" title="Law of superposition">law of superposition</a>.</figcaption></figure> <figure class="mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Lava_flow_and_crater_ejecta.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/28/Lava_flow_and_crater_ejecta.JPG/240px-Lava_flow_and_crater_ejecta.JPG" decoding="async" width="240" height="226" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/28/Lava_flow_and_crater_ejecta.JPG/360px-Lava_flow_and_crater_ejecta.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/28/Lava_flow_and_crater_ejecta.JPG/480px-Lava_flow_and_crater_ejecta.JPG 2x" data-file-width="490" data-file-height="462" /></a><figcaption><a href="/wiki/HiRISE" title="HiRISE">HiRISE</a> image illustrating <a href="/wiki/Law_of_superposition" title="Law of superposition">superpositioning</a>, a principle that lets geologists determine the relative ages of surface units. The dark-toned lava flow overlies (is younger than) the light-toned, more heavily cratered terrain at right. The ejecta of the crater at center overlies both units, indicating that the crater is the youngest feature in the image. (See cross section, above right.)</figcaption></figure> <p>Martian time periods are based on <a href="/wiki/Geologic_map" title="Geologic map">geologic mapping</a> of surface units from <a href="/wiki/Remote_sensing" title="Remote sensing">spacecraft images</a>.<sup id="cite_ref-ScottCarr78_12-1" class="reference"><a href="#cite_note-ScottCarr78-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> A surface unit is a terrain with a distinct texture, color, <a href="/wiki/Albedo" title="Albedo">albedo</a>, <a href="/wiki/Thermal_infrared_spectroscopy" title="Thermal infrared spectroscopy">spectral</a> property, or set of landforms that distinguish it from other surface units and is large enough to be shown on a map.<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> Mappers use a <a href="/wiki/Stratigraphy" title="Stratigraphy">stratigraphic</a> approach pioneered in the early 1960s for photogeologic studies of the <a href="/wiki/Geology_of_the_Moon" title="Geology of the Moon">Moon</a>.<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> Although based on surface characteristics, a surface unit is not the surface itself or group of <a href="/wiki/Landform" title="Landform">landforms</a>. It is an <i>inferred</i> <a href="/wiki/Geological_unit" class="mw-redirect" title="Geological unit">geologic unit</a> (e.g., <a href="/wiki/Formation_(stratigraphy)" class="mw-redirect" title="Formation (stratigraphy)">formation</a>) representing a sheetlike, wedgelike, or tabular body of rock that underlies the surface.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Tanaka92_20-0" class="reference"><a href="#cite_note-Tanaka92-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> A surface unit may be a crater ejecta deposit, lava flow, or any surface that can be represented in three dimensions as a discrete <a href="/wiki/Stratum" title="Stratum">stratum</a> bound above or below by adjacent units (illustrated right). Using principles such as <a href="/wiki/Law_of_superposition" title="Law of superposition">superpositioning</a> (illustrated left), <a href="/wiki/Cross-cutting_relationships" title="Cross-cutting relationships">cross-cutting relationships</a>, and the relationship of <a href="/wiki/Geological_history_of_Mars" title="Geological history of Mars">impact crater density</a> to age, geologists can place the units into a <a href="/wiki/Relative_dating" title="Relative dating">relative age</a> sequence from oldest to youngest. Units of similar age are grouped globally into larger, time-stratigraphic (<a href="/wiki/Chronostratigraphy" title="Chronostratigraphy">chronostratigraphic</a>) units, called <a href="/wiki/System_(stratigraphy)" title="System (stratigraphy)">systems</a>. For Mars, four systems are defined: the Pre-Noachian, <a href="/wiki/Noachian_(Mars)" class="mw-redirect" title="Noachian (Mars)">Noachian</a>, Hesperian, and Amazonian. Geologic units lying below (older than) the Noachian are informally designated Pre-Noachian.<sup id="cite_ref-NimmoTanaka05_21-0" class="reference"><a href="#cite_note-NimmoTanaka05-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> The geologic time (<a href="/wiki/Geochronology" title="Geochronology">geochronologic</a>) equivalent of the Hesperian System is the Hesperian Period. Rock or surface units of the Hesperian System were formed or deposited during the Hesperian Period. </p> <div class="mw-heading mw-heading3"><h3 id="System_vs._period">System vs. period</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Hesperian&action=edit&section=3" title="Edit section: System vs. period"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <table class="wikitable" style="float:right; font-size:90%; width:400px; margin-left:5px;"> <tbody><tr> <td colspan="3"><span style="float:right;"><span class="plainlinksneverexpand"><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Template:Geology_to_Paleobiology&action=edit">e</a>  <a class="external text" href="https://en.wikipedia.org/w/index.php?title=Template:Geology_to_Paleobiology&action=history">h</a></span></span><div style="text-align: center;"><big><b><a href="/wiki/Geologic_time_scale" title="Geologic time scale">Units in Earth geochronology and stratigraphy</a></b></big><sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup></div> </td></tr> <tr> <th>Segments of rock (<a href="/wiki/Stratum" title="Stratum">strata</a>) in <a href="/wiki/Chronostratigraphy" title="Chronostratigraphy">chronostratigraphy</a> </th> <th>Periods of time in <a href="/wiki/Geochronology" title="Geochronology">geochronology</a> </th> <th>Notes (Mars) </th></tr> <tr> <td style="text-align: center;"><a href="/wiki/Eonothem" title="Eonothem">Eonothem</a></td> <td style="text-align: center;"><a href="/wiki/Eon_(geology)" class="mw-redirect" title="Eon (geology)">Eon</a></td> <td>not used for Mars </td></tr> <tr> <td style="text-align: center;"><a href="/wiki/Erathem" title="Erathem">Erathem</a></td> <td style="text-align: center;"><a href="/wiki/Era_(geology)" class="mw-redirect" title="Era (geology)">Era</a></td> <td>not used for Mars </td></tr> <tr> <td style="text-align: center;"><a href="/wiki/System_(stratigraphy)" title="System (stratigraphy)">System</a></td> <td style="text-align: center;"><a href="/wiki/Period_(geology)" class="mw-redirect" title="Period (geology)">Period</a></td> <td>3 total; 10<sup>8</sup> to 10<sup>9</sup> years in length </td></tr> <tr> <td style="text-align: center;"><a href="/wiki/Series_(stratigraphy)" title="Series (stratigraphy)">Series</a></td> <td style="text-align: center;"><a href="/wiki/Epoch_(geology)" class="mw-redirect" title="Epoch (geology)">Epoch</a></td> <td>8 total; 10<sup>7</sup> to 10<sup>8</sup> years in length </td></tr> <tr> <td style="text-align: center;"><a href="/wiki/Stage_(stratigraphy)" title="Stage (stratigraphy)">Stage</a></td> <td style="text-align: center;"><a href="/wiki/Age_(geology)" class="mw-redirect" title="Age (geology)">Age</a></td> <td>not used for Mars </td></tr> <tr> <td style="text-align: center;"><a href="/wiki/Chronozone" title="Chronozone">Chronozone</a></td> <td style="text-align: center;"><a href="/wiki/Polarity_chron" class="mw-redirect" title="Polarity chron">Chron</a></td> <td>smaller than an age/stage; not used by the ICS timescale </td></tr></tbody></table> <p><i>System</i> and <i>period</i> are not interchangeable terms in formal stratigraphic nomenclature, although they are frequently confused in popular literature. A system is an idealized stratigraphic <a href="/wiki/Geologic_record" title="Geologic record">column</a> based on the physical rock record of a <a href="/wiki/Type_locality_(geology)" title="Type locality (geology)">type area</a> (type section) correlated with rocks sections from many different locations planetwide.<sup id="cite_ref-EicherMcAlester80_23-0" class="reference"><a href="#cite_note-EicherMcAlester80-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> A system is bound above and below by <a href="/wiki/Stratum" title="Stratum">strata</a> with distinctly different characteristics (on Earth, usually <a href="/wiki/Index_fossil" class="mw-redirect" title="Index fossil">index fossils</a>) that indicate dramatic (often abrupt) changes in the dominant fauna or environmental conditions. (See <a href="/wiki/Cretaceous%E2%80%93Paleogene_boundary" title="Cretaceous–Paleogene boundary">Cretaceous–Paleogene boundary</a> as example.) </p><p>At any location, rock sections in a given system are apt to contain gaps (<a href="/wiki/Unconformity" title="Unconformity">unconformities</a>) analogous to missing pages from a book. In some places, rocks from the system are absent entirely due to nondeposition or later erosion. For example, rocks of the <a href="/wiki/Cretaceous" title="Cretaceous">Cretaceous</a> System are absent throughout much of the eastern central interior of the United States. However, the time interval of the Cretaceous (Cretaceous Period) still occurred there. Thus, a geologic period represents the time interval over which the <a href="/wiki/Stratum" title="Stratum">strata</a> of a system were deposited, including any unknown amounts of time present in gaps.<sup id="cite_ref-EicherMcAlester80_23-1" class="reference"><a href="#cite_note-EicherMcAlester80-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> Periods are measured in years, determined by <a href="/wiki/Radioactive_dating" class="mw-redirect" title="Radioactive dating">radioactive dating</a>. On Mars, radiometric ages are not available except from <a href="/wiki/Martian_meteorites" class="mw-redirect" title="Martian meteorites">Martian meteorites</a> whose <a href="/wiki/Provenance" title="Provenance">provenance</a> and stratigraphic context are unknown. Instead, <a href="/wiki/Absolute_age" class="mw-redirect" title="Absolute age">absolute ages</a> on Mars are determined by impact crater density, which is heavily dependent upon <a href="/wiki/Scientific_modelling" title="Scientific modelling">models</a> of crater formation over time.<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> Accordingly, the beginning and end dates for Martian periods are uncertain, especially for the Hesperian/Amazonian boundary, which may be in error by a factor of 2 or 3.<sup id="cite_ref-HartmannNeukum_4-1" class="reference"><a href="#cite_note-HartmannNeukum-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-NimmoTanaka05_21-1" class="reference"><a href="#cite_note-NimmoTanaka05-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Boundaries_and_subdivisions">Boundaries and subdivisions</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Hesperian&action=edit&section=4" title="Edit section: Boundaries and subdivisions"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Ridged_Plains_Overlying_Noachian.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/44/Ridged_Plains_Overlying_Noachian.jpg/250px-Ridged_Plains_Overlying_Noachian.jpg" decoding="async" width="250" height="263" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/44/Ridged_Plains_Overlying_Noachian.jpg/375px-Ridged_Plains_Overlying_Noachian.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/44/Ridged_Plains_Overlying_Noachian.jpg/500px-Ridged_Plains_Overlying_Noachian.jpg 2x" data-file-width="800" data-file-height="841" /></a><figcaption>Geologic contact of Noachian and Hesperian Systems. Hesperian ridged plains (Hr) embay and overlie older Noachian cratered plateau materials (Npl). The ridged plains partially bury many of the old Noachian-aged craters. Image is <a href="/wiki/Thermal_Emission_Imaging_System" title="Thermal Emission Imaging System">THEMIS</a> IR mosaic, based on similar <a href="/wiki/Viking_program" title="Viking program">Viking</a> photo shown in Tanaka <i>et al.</i> (1992), Fig. 1a, p. 352.</figcaption></figure> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Hesperian_Amazonian_contact.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/en/thumb/d/d3/Hesperian_Amazonian_contact.jpg/250px-Hesperian_Amazonian_contact.jpg" decoding="async" width="250" height="250" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/d/d3/Hesperian_Amazonian_contact.jpg/375px-Hesperian_Amazonian_contact.jpg 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/d/d3/Hesperian_Amazonian_contact.jpg/500px-Hesperian_Amazonian_contact.jpg 2x" data-file-width="857" data-file-height="857" /></a><figcaption>Approximate geologic contact of Upper Hesperian lava apron from <a href="/wiki/Alba_Mons" title="Alba Mons">Alba Mons</a> (H<sub>al</sub>) with Lower Amazonian Vastitas Borealis Formation (A<sub>vb</sub>). Image is <a href="/wiki/Mars_Orbital_Laser_Altimeter" class="mw-redirect" title="Mars Orbital Laser Altimeter">MOLA</a> topographic map adapted from Ivanov and Head (2006), Figs. 1, 3, and 8.<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup></figcaption></figure> <p>The lower boundary of the Hesperian System is defined as the base of the ridged plains, which are typified by Hesperia Planum and cover about a third of the planet's surface.<sup id="cite_ref-Tanaka86_3-2" class="reference"><a href="#cite_note-Tanaka86-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> In eastern Hesperia Planum, the ridged plains overlie early to mid Noachian aged cratered plateau materials (pictured left).<sup id="cite_ref-GreeleyGuest87_15-1" class="reference"><a href="#cite_note-GreeleyGuest87-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> The Hesperian's upper boundary is more complex and has been redefined several times based on increasingly detailed geologic mapping.<sup id="cite_ref-Tanaka86_3-3" class="reference"><a href="#cite_note-Tanaka86-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-ScottCarr78_12-2" class="reference"><a href="#cite_note-ScottCarr78-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Tanakaetal05_26-0" class="reference"><a href="#cite_note-Tanakaetal05-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> Currently, the stratigraphic boundary of the Hesperian with the younger Amazonian System is defined as the base of the Vastitas Borealis Formation<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> (pictured right). The <a href="/wiki/Vastitas_Borealis" title="Vastitas Borealis">Vastitas Borealis</a> is a vast, low-lying plain that covers much of the northern hemisphere of Mars. It is generally interpreted to consist of reworked sediments originating from the Late Hesperian outflow channels and may be the remnant of an ocean that covered the northern lowland basins. Another interpretation of the Vastitas Borealis Formation is that it consists of lava flows.<sup id="cite_ref-28" class="reference"><a href="#cite_note-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> </p><p>The Hesperian System is subdivided into two chronostratigraphic <a href="/wiki/Series_(stratigraphy)" title="Series (stratigraphy)">series</a>: Lower Hesperian and Upper Hesperian. The series are based on <i>referents</i> or locations on the planet where surface units indicate a distinctive geological episode, recognizable in time by cratering age and stratigraphic position. For example, Hesperia Planum is the referent location for the Lower Hesperian Series.<sup id="cite_ref-Tanaka86_3-4" class="reference"><a href="#cite_note-Tanaka86-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Masson90_29-0" class="reference"><a href="#cite_note-Masson90-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> The corresponding geologic time (geochronological) units of the two Hesperian series are the Early Hesperian and Late Hesperian <a href="/wiki/Epoch_(geology)" class="mw-redirect" title="Epoch (geology)">Epochs</a>. An epoch is a subdivision of a period; the two terms are not synonymous in formal stratigraphy. The age of the Early Hepserian/Late Hesperian boundary is uncertain, ranging from 3600 to 3200 million years ago based on crater counts.<sup id="cite_ref-Hartmann05_5-1" class="reference"><a href="#cite_note-Hartmann05-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> The average of the range is shown in the timeline below. </p> <div class="timeline-wrapper"><map name="timeline_n32p86p8xuqcpquuj7yz4shoz4avtt6"></map><img usemap="#timeline_n32p86p8xuqcpquuj7yz4shoz4avtt6" src="//upload.wikimedia.org/wikipedia/en/timeline/n32p86p8xuqcpquuj7yz4shoz4avtt6.png" /></div> <div class="center" style="width:auto; margin-left:auto; margin-right:auto;"><small>Hesperian Epochs (Millions of Years Ago)</small><sup id="cite_ref-Hartmann05_5-2" class="reference"><a href="#cite_note-Hartmann05-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup></div> <p>Stratigraphic terms are typically confusing to geologists and non-geologists alike. One way to sort through the difficulty is by the following example: One could easily go to <a href="/wiki/Cincinnati,_Ohio" class="mw-redirect" title="Cincinnati, Ohio">Cincinnati, Ohio</a> and visit a rock <a href="/wiki/Outcrop" title="Outcrop">outcrop</a> in the Upper <a href="/wiki/Ordovician" title="Ordovician">Ordovician</a> <i>Series</i> of the Ordovician <i>System.</i> You could even collect a fossil <a href="/wiki/Trilobite" title="Trilobite">trilobite</a> there. However, you could not visit the Late Ordovician <i>Epoch</i> in the Ordovician <i>Period</i> and collect an actual trilobite. </p><p>The Earth-based scheme of rigid stratigraphic nomenclature has been successfully applied to Mars for several decades now but has numerous flaws. The scheme will no doubt become refined or replaced as more and better data become available.<sup id="cite_ref-30" class="reference"><a href="#cite_note-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> (See mineralogical timeline below as example of alternative.) Obtaining radiometric ages on samples from identified surface units is clearly necessary for a more complete understanding of Martian chronology.<sup id="cite_ref-31" class="reference"><a href="#cite_note-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Mars_during_the_Hesperian_Period">Mars during the Hesperian Period</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Hesperian&action=edit&section=5" title="Edit section: Mars during the Hesperian Period"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Hesperian_Surface_130S09.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/en/thumb/6/60/Hesperian_Surface_130S09.jpg/250px-Hesperian_Surface_130S09.jpg" decoding="async" width="250" height="219" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/6/60/Hesperian_Surface_130S09.jpg/375px-Hesperian_Surface_130S09.jpg 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/6/60/Hesperian_Surface_130S09.jpg/500px-Hesperian_Surface_130S09.jpg 2x" data-file-width="1204" data-file-height="1056" /></a><figcaption><a href="/wiki/Viking_program" title="Viking program">Viking orbiter</a> view of Hesperian-aged surface in <a href="/wiki/Terra_Meridiani" class="mw-redirect" title="Terra Meridiani">Terra Meridiani</a>. The small impact craters date back to the Hesperian Period and appear crisp despite their great age. This image indicates that erosion on Mars has been very slow since the end of the <a href="/wiki/Noachian" title="Noachian">Noachian</a>. Image is 17 km across and based on Carr, 1996, p. 134, Fig. 6-8.<sup id="cite_ref-Carr96_32-0" class="reference"><a href="#cite_note-Carr96-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup></figcaption></figure> <p>The Hesperian was a time of declining rates of impact cratering, intense and widespread volcanic activity, and catastrophic flooding. Many of the major <a href="/wiki/Tectonics" title="Tectonics">tectonic</a> features on Mars formed at this time. The weight of the immense <a href="/wiki/Tharsis" title="Tharsis">Tharsis Bulge</a> stressed the crust to produce a vast network of extensional fractures (<a href="/wiki/Fossa_(geology)" class="mw-redirect" title="Fossa (geology)">fossae</a>) and compressive deformational features (<a href="/wiki/Wrinkle_ridge" title="Wrinkle ridge">wrinkle ridges</a>) throughout the western hemisphere. The huge equatorial canyon system of <a href="/wiki/Valles_Marineris" title="Valles Marineris">Valles Marineris</a> formed during the Hesperian as a result of these stresses. Sulfuric-acid weathering at the surface produced an abundance of sulfate minerals that precipitated in <a href="/wiki/Evaporite" title="Evaporite">evaporitic environments</a>, which became widespread as the planet grew increasingly arid. The Hesperian Period was also a time when the earliest evidence of glacial activity and ice-related processes appears in the Martian geologic record. </p> <div class="mw-heading mw-heading3"><h3 id="Impact_cratering">Impact cratering</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Hesperian&action=edit&section=6" title="Edit section: Impact cratering"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>As originally conceived, the Hesperian System referred to the oldest surfaces on Mars that postdate the end of <a href="/wiki/Late_Heavy_Bombardment" title="Late Heavy Bombardment">heavy bombardment</a>.<sup id="cite_ref-33" class="reference"><a href="#cite_note-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> The Hesperian was thus a time period of rapidly declining impact cratering rates. However, the timing and rate of the decline are uncertain. The lunar cratering record suggests that the rate of impacts in the inner <a href="/wiki/Solar_System" title="Solar System">Solar System</a> during the <a href="/wiki/Noachian" title="Noachian">Noachian</a> (4000 million years ago) was 500 times higher than today.<sup id="cite_ref-34" class="reference"><a href="#cite_note-34"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> Planetary scientists still debate whether these high rates represent the tail end of <a href="/wiki/Planetary_accretion" class="mw-redirect" title="Planetary accretion">planetary accretion</a> or a late cataclysmic pulse that followed a more quiescent period of impact activity. Nevertheless, at the beginning of the Hesperian, the impact rate had probably declined to about 80 times greater than present rates,<sup id="cite_ref-HartmannNeukum_4-2" class="reference"><a href="#cite_note-HartmannNeukum-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> and by the end of the Hesperian, some 700 million years later, the rate began to resemble that seen today.<sup id="cite_ref-FassettHead11_35-0" class="reference"><a href="#cite_note-FassettHead11-35"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> </p> <div style="clear:both;" class=""></div> <div class="mw-heading mw-heading2"><h2 id="Notes_and_references">Notes and references</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Hesperian&action=edit&section=7" title="Edit section: Notes and 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-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text">Hartmann, 2003, pp. 33–34.</span> </li> <li id="cite_note-CarrHead10-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-CarrHead10_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-CarrHead10_2-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-CarrHead10_2-2"><sup><i><b>c</b></i></sup></a></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="CITEREFCarrHead2010" class="citation journal cs1">Carr, M. 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(2011). The Noachian-Hesperian Transition on Mars: Geological Evidence for a Punctuated Phase of Global Volcanism as a Key Driver in Climate and Atmospheric Evolution. 42nd Lunar and Planetary Science Conference (2011), Abstract #1214. <a rel="nofollow" class="external free" href="http://www.lpi.usra.edu/meetings/lpsc2011/pdf/1214.pdf">http://www.lpi.usra.edu/meetings/lpsc2011/pdf/1214.pdf</a>.</span> </li> <li id="cite_note-Barlow10-10"><span class="mw-cite-backlink">^ <a href="#cite_ref-Barlow10_10-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Barlow10_10-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBarlow2010" class="citation journal cs1">Barlow, N. G. (2010). "What we know about Mars from its impact craters". <i>Geological Society of America Bulletin</i>. <b>122</b> (<span class="nowrap">5–</span>6): <span class="nowrap">644–</span>657. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2010GSAB..122..644B">2010GSAB..122..644B</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1130%2FB30182.1">10.1130/B30182.1</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Geological+Society+of+America+Bulletin&rft.atitle=What+we+know+about+Mars+from+its+impact+craters&rft.volume=122&rft.issue=%3Cspan+class%3D%22nowrap%22%3E5%E2%80%93%3C%2Fspan%3E6&rft.pages=%3Cspan+class%3D%22nowrap%22%3E644-%3C%2Fspan%3E657&rft.date=2010&rft_id=info%3Adoi%2F10.1130%2FB30182.1&rft_id=info%3Abibcode%2F2010GSAB..122..644B&rft.aulast=Barlow&rft.aufirst=N.+G.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHesperian" class="Z3988"></span></span> </li> <li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFClifford1993" class="citation journal cs1">Clifford, S. M. (1993). "A model for the hydrologic and climatic behavior of water on Mars". <i>Journal of Geophysical Research</i>. <b>98</b> (E6): <span class="nowrap">10973–</span>11016. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1993JGR....9810973C">1993JGR....9810973C</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1029%2F93JE00225">10.1029/93JE00225</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+Geophysical+Research&rft.atitle=A+model+for+the+hydrologic+and+climatic+behavior+of+water+on+Mars&rft.volume=98&rft.issue=E6&rft.pages=%3Cspan+class%3D%22nowrap%22%3E10973-%3C%2Fspan%3E11016&rft.date=1993&rft_id=info%3Adoi%2F10.1029%2F93JE00225&rft_id=info%3Abibcode%2F1993JGR....9810973C&rft.aulast=Clifford&rft.aufirst=S.+M.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHesperian" class="Z3988"></span></span> </li> <li id="cite_note-ScottCarr78-12"><span class="mw-cite-backlink">^ <a href="#cite_ref-ScottCarr78_12-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-ScottCarr78_12-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-ScottCarr78_12-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text">Scott, D.H.; Carr, M.H. (1978). Geologic Map of Mars. U.S. Geological Survey Miscellaneous Investigations Series Map I-1083.</span> </li> <li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text">Strom, R.G.; Croft, S.K.; Barlow, N.G. (1992) The Martian Impact Cratering Record in <i>Mars,</i> H.H. Kieffer <i>et al.,</i> Eds.; University of Arizona Press: Tucson, AZ, pp. 383–423.</span> </li> <li id="cite_note-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-14">^</a></b></span> <span class="reference-text">Scott, D.H.; Tanaka, K.L. (1986). Geologic Map of the Western Equatorial Region of Mars. U.S. Geological Survey Miscellaneous Investigations Series Map I–1802–A.</span> </li> <li id="cite_note-GreeleyGuest87-15"><span class="mw-cite-backlink">^ <a href="#cite_ref-GreeleyGuest87_15-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-GreeleyGuest87_15-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Greeley, R.; Guest, J.E. (1987). Geologic Map of the Eastern Equatorial Region of Mars. U.S. Geological Survey Miscellaneous Investigations Series Map I–1802–B.</span> </li> <li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text">McCord, T.M. <i>et al.</i> (1980). Definition and Characterization of Mars Global Surface Units: Preliminary Unit Maps. 11th Lunar and Planetary Science Conference: Houston: TX, abstract #1249, pp. 697–699. <a rel="nofollow" class="external free" href="http://www.lpi.usra.edu/meetings/lpsc1980/pdf/1249.pdf">http://www.lpi.usra.edu/meetings/lpsc1980/pdf/1249.pdf</a>.</span> </li> <li id="cite_note-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-17">^</a></b></span> <span class="reference-text">Greeley, R. (1994) <i>Planetary Landscapes,</i> 2nd ed.; Chapman & Hall: New York, p. 8 and Fig. 1.6.</span> </li> <li id="cite_note-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-18">^</a></b></span> <span class="reference-text">See Mutch, T.A. (1970). <i>Geology of the Moon: A Stratigraphic View;</i> Princeton University Press: Princeton, NJ, 324 pp. and Wilhelms, D.E. (1987). <i>The Geologic History of the Moon,</i> USGS Professional Paper 1348; <a rel="nofollow" class="external free" href="http://ser.sese.asu.edu/GHM/">http://ser.sese.asu.edu/GHM/</a> for reviews of this topic.</span> </li> <li id="cite_note-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-19">^</a></b></span> <span class="reference-text">Wilhelms, D.E. (1990). Geologic Mapping in <i>Planetary Mapping,</i> R. Greeley, R.M. Batson, Eds.; Cambridge University Press: Cambridge UK, p. 214.</span> </li> <li id="cite_note-Tanaka92-20"><span class="mw-cite-backlink"><b><a href="#cite_ref-Tanaka92_20-0">^</a></b></span> <span class="reference-text">Tanaka, K.L.; Scott, D.H.; Greeley, R. (1992). Global Stratigraphy in <i>Mars,</i> H.H. Kieffer <i>et al.,</i> Eds.; University of Arizona Press: Tucson, AZ, pp. 345–382.</span> </li> <li id="cite_note-NimmoTanaka05-21"><span class="mw-cite-backlink">^ <a href="#cite_ref-NimmoTanaka05_21-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NimmoTanaka05_21-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFNimmoTanaka2005" class="citation journal cs1">Nimmo, F.; Tanaka, K. (2005). "Early Crustal Evolution of Mars". <i>Annual Review of Earth and Planetary Sciences</i>. <b>33</b> (1): <span class="nowrap">133–</span>161. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2005AREPS..33..133N">2005AREPS..33..133N</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1146%2Fannurev.earth.33.092203.122637">10.1146/annurev.earth.33.092203.122637</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Annual+Review+of+Earth+and+Planetary+Sciences&rft.atitle=Early+Crustal+Evolution+of+Mars&rft.volume=33&rft.issue=1&rft.pages=%3Cspan+class%3D%22nowrap%22%3E133-%3C%2Fspan%3E161&rft.date=2005&rft_id=info%3Adoi%2F10.1146%2Fannurev.earth.33.092203.122637&rft_id=info%3Abibcode%2F2005AREPS..33..133N&rft.aulast=Nimmo&rft.aufirst=F.&rft.au=Tanaka%2C+K.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHesperian" class="Z3988"></span></span> </li> <li id="cite_note-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-22">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFInternational_Commission_on_Stratigraphy" class="citation web cs1"><a href="/wiki/International_Commission_on_Stratigraphy" title="International Commission on Stratigraphy">International Commission on Stratigraphy</a>. <a rel="nofollow" class="external text" href="http://www.stratigraphy.org/upload/ISChart2009.pdf">"International Stratigraphic Chart"</a> <span class="cs1-format">(PDF)</span><span class="reference-accessdate">. Retrieved <span class="nowrap">2009-09-25</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=International+Stratigraphic+Chart&rft.au=International+Commission+on+Stratigraphy&rft_id=http%3A%2F%2Fwww.stratigraphy.org%2Fupload%2FISChart2009.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHesperian" class="Z3988"></span></span> </li> <li id="cite_note-EicherMcAlester80-23"><span class="mw-cite-backlink">^ <a href="#cite_ref-EicherMcAlester80_23-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-EicherMcAlester80_23-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">Eicher, D.L.; McAlester, A.L. (1980). <i>History of the Earth;</i> Prentice-Hall: Englewood Cliffs, NJ, pp 143–146, <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/0-13-390047-9" title="Special:BookSources/0-13-390047-9">0-13-390047-9</a>.</span> </li> <li id="cite_note-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-24">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMassonCarrCostardGreeley2001" class="citation journal cs1">Masson, P.; Carr, M.H.; Costard, F.; Greeley, R.; Hauber, E.; Jaumann, R. (2001). "Geomorphologic Evidence for Liquid Water". <i>Space Science Reviews</i>. Space Sciences Series of ISSI. <b>96</b>: <span class="nowrap">333–</span>364. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2F978-94-017-1035-0_12">10.1007/978-94-017-1035-0_12</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-90-481-5725-9" title="Special:BookSources/978-90-481-5725-9"><bdi>978-90-481-5725-9</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Space+Science+Reviews&rft.atitle=Geomorphologic+Evidence+for+Liquid+Water&rft.volume=96&rft.pages=%3Cspan+class%3D%22nowrap%22%3E333-%3C%2Fspan%3E364&rft.date=2001&rft_id=info%3Adoi%2F10.1007%2F978-94-017-1035-0_12&rft.isbn=978-90-481-5725-9&rft.aulast=Masson&rft.aufirst=P.&rft.au=Carr%2C+M.H.&rft.au=Costard%2C+F.&rft.au=Greeley%2C+R.&rft.au=Hauber%2C+E.&rft.au=Jaumann%2C+R.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHesperian" class="Z3988"></span></span> </li> <li id="cite_note-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-25">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFIvanovHead2006" class="citation journal cs1">Ivanov, M. A.; Head, J. W. (2006). <a rel="nofollow" class="external text" href="https://doi.org/10.1029%2F2005JE002469">"Alba Patera, Mars: Topography, structure, and evolution of a unique late Hesperian–early Amazonian shield volcano"</a>. <i>Journal of Geophysical Research</i>. <b>111</b> (E9): E09003. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2006JGRE..111.9003I">2006JGRE..111.9003I</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1029%2F2005JE002469">10.1029/2005JE002469</a></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+Geophysical+Research&rft.atitle=Alba+Patera%2C+Mars%3A+Topography%2C+structure%2C+and+evolution+of+a+unique+late+Hesperian%E2%80%93early+Amazonian+shield+volcano&rft.volume=111&rft.issue=E9&rft.pages=E09003&rft.date=2006&rft_id=info%3Adoi%2F10.1029%2F2005JE002469&rft_id=info%3Abibcode%2F2006JGRE..111.9003I&rft.aulast=Ivanov&rft.aufirst=M.+A.&rft.au=Head%2C+J.+W.&rft_id=https%3A%2F%2Fdoi.org%2F10.1029%252F2005JE002469&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHesperian" class="Z3988"></span></span> </li> <li id="cite_note-Tanakaetal05-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-Tanakaetal05_26-0">^</a></b></span> <span class="reference-text">Tanaka, K.L.; Skinner, J.A.; Hare, T.M. (2005). Geologic Map of the Northern Plains of Mars. Scientific Investigations Map 2888, Pamphlet; U.S. Geological Survey.</span> </li> <li id="cite_note-27"><span class="mw-cite-backlink"><b><a href="#cite_ref-27">^</a></b></span> <span class="reference-text">The Vastitas Borealis Formation is used here to include the Lower Amazonian Scandia, Vastitas Borealis interior, and Vastitas Borealis marginal units of Tanaka <i>et al.</i> (2005).</span> </li> <li id="cite_note-28"><span class="mw-cite-backlink"><b><a href="#cite_ref-28">^</a></b></span> <span class="reference-text">Catling, D.C.; Leovy, C.B.; Wood, S.E.; Day, M.D. (2011). A Lava Sea in the Northern Plains of Mars: Circumpolar Hesperian Oceans Reconsidered. 42nd Lunar and Planetary Science Conference, Abstract #2529. <a rel="nofollow" class="external free" href="http://www.lpi.usra.edu/meetings/lpsc2011/pdf/2529.pdf">http://www.lpi.usra.edu/meetings/lpsc2011/pdf/2529.pdf</a>.</span> </li> <li id="cite_note-Masson90-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-Masson90_29-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMasson1991" class="citation journal cs1">Masson, P. L. (1991). "The Martian stratigraphy — Short review and perspectives". <i>Space Science Reviews</i>. <b>56</b> (<span class="nowrap">1–</span>2): <span class="nowrap">9–</span>12. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1991SSRv...56....9M">1991SSRv...56....9M</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2FBF00178385">10.1007/BF00178385</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:121719547">121719547</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Space+Science+Reviews&rft.atitle=The+Martian+stratigraphy+%E2%80%94+Short+review+and+perspectives&rft.volume=56&rft.issue=%3Cspan+class%3D%22nowrap%22%3E1%E2%80%93%3C%2Fspan%3E2&rft.pages=%3Cspan+class%3D%22nowrap%22%3E9-%3C%2Fspan%3E12&rft.date=1991&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A121719547%23id-name%3DS2CID&rft_id=info%3Adoi%2F10.1007%2FBF00178385&rft_id=info%3Abibcode%2F1991SSRv...56....9M&rft.aulast=Masson&rft.aufirst=P.+L.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHesperian" class="Z3988"></span></span> </li> <li id="cite_note-30"><span class="mw-cite-backlink"><b><a href="#cite_ref-30">^</a></b></span> <span class="reference-text">Tanaka, K.L. (2001). The Stratigraphy of Mars: What We Know, Don't Know, and Need to Do. 32nd Lunar and Planetary Science Conference, Abstract #1695. <a rel="nofollow" class="external free" href="http://www.lpi.usra.edu/meetings/lpsc2001/pdf/1695.pdf">http://www.lpi.usra.edu/meetings/lpsc2001/pdf/1695.pdf</a>.</span> </li> <li id="cite_note-31"><span class="mw-cite-backlink"><b><a href="#cite_ref-31">^</a></b></span> <span class="reference-text">Carr, 2006, p. 41.</span> </li> <li id="cite_note-Carr96-32"><span class="mw-cite-backlink"><b><a href="#cite_ref-Carr96_32-0">^</a></b></span> <span class="reference-text">Carr, M.H. (1996). <i>Water on Mars;</i> Oxford University Press: Oxford, UK, 229 pp, <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/0-19-509938-9" title="Special:BookSources/0-19-509938-9">0-19-509938-9</a>.</span> </li> <li id="cite_note-33"><span class="mw-cite-backlink"><b><a href="#cite_ref-33">^</a></b></span> <span class="reference-text">Carr, 2006, p. 15.</span> </li> <li id="cite_note-34"><span class="mw-cite-backlink"><b><a href="#cite_ref-34">^</a></b></span> <span class="reference-text">Carr, 2006, p. 23.</span> </li> <li id="cite_note-FassettHead11-35"><span class="mw-cite-backlink"><b><a href="#cite_ref-FassettHead11_35-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFFassettHead2011" class="citation journal cs1">Fassett, C. I.; Head, J. W. (2011). "Sequence and timing of conditions on early Mars". <i>Icarus</i>. <b>211</b> (2): <span class="nowrap">1204–</span>1214. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2011Icar..211.1204F">2011Icar..211.1204F</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2Fj.icarus.2010.11.014">10.1016/j.icarus.2010.11.014</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Icarus&rft.atitle=Sequence+and+timing+of+conditions+on+early+Mars&rft.volume=211&rft.issue=2&rft.pages=%3Cspan+class%3D%22nowrap%22%3E1204-%3C%2Fspan%3E1214&rft.date=2011&rft_id=info%3Adoi%2F10.1016%2Fj.icarus.2010.11.014&rft_id=info%3Abibcode%2F2011Icar..211.1204F&rft.aulast=Fassett&rft.aufirst=C.+I.&rft.au=Head%2C+J.+W.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHesperian" class="Z3988"></span></span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="Bibliography_and_recommended_reading">Bibliography and recommended reading</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Hesperian&action=edit&section=8" title="Edit section: Bibliography and recommended reading"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBoyce2008" class="citation book cs1">Boyce, Joseph M. (2008). <a rel="nofollow" class="external text" href="https://archive.org/details/smithsonianbooko00boyc"><i>The Smithsonian Book of Mars</i></a>. Old Saybrook, CT: Konecky & Konecky. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-58834-074-0" title="Special:BookSources/978-1-58834-074-0"><bdi>978-1-58834-074-0</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+Smithsonian+Book+of+Mars&rft.place=Old+Saybrook%2C+CT&rft.pub=Konecky+%26+Konecky&rft.date=2008&rft.isbn=978-1-58834-074-0&rft.aulast=Boyce&rft.aufirst=Joseph+M.&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fsmithsonianbooko00boyc&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHesperian" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFCarr2006" class="citation book cs1">Carr, Michael H. (2006). <i>The Surface of Mars</i>. Cambridge, UK: Cambridge University Press. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-521-87201-0" title="Special:BookSources/978-0-521-87201-0"><bdi>978-0-521-87201-0</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+Surface+of+Mars&rft.place=Cambridge%2C+UK&rft.pub=Cambridge+University+Press&rft.date=2006&rft.isbn=978-0-521-87201-0&rft.aulast=Carr&rft.aufirst=Michael+H.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHesperian" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHartmann2003" class="citation book cs1">Hartmann, William K. (2003). <a rel="nofollow" class="external text" href="https://archive.org/details/travelersguideto00will"><i>A Traveler's Guide to Mars: The Mysterious Landscapes of the Red Planet</i></a>. New York: Workman. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-7611-2606-6" title="Special:BookSources/0-7611-2606-6"><bdi>0-7611-2606-6</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=A+Traveler%27s+Guide+to+Mars%3A+The+Mysterious+Landscapes+of+the+Red+Planet&rft.place=New+York&rft.pub=Workman&rft.date=2003&rft.isbn=0-7611-2606-6&rft.aulast=Hartmann&rft.aufirst=William+K.&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Ftravelersguideto00will&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHesperian" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMorton2003" class="citation book cs1">Morton, Oliver (2003). <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/mappingmars00oliv"><i>Mapping Mars: Science, Imagination, and the Birth of a World</i></a></span>. New York: Picador. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-312-42261-X" title="Special:BookSources/0-312-42261-X"><bdi>0-312-42261-X</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Mapping+Mars%3A+Science%2C+Imagination%2C+and+the+Birth+of+a+World&rft.place=New+York&rft.pub=Picador&rft.date=2003&rft.isbn=0-312-42261-X&rft.aulast=Morton&rft.aufirst=Oliver&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fmappingmars00oliv&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHesperian" class="Z3988"></span></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 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title="Atmosphere of Mars">Atmosphere</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Mars_general_circulation_model" title="Mars general circulation model">Circulation</a></li> <li><a href="/wiki/Climate_of_Mars" title="Climate of Mars">Climate</a></li> <li><a href="/wiki/Martian_dust_devils" title="Martian dust devils">Dust devil tracks</a></li> <li><a href="/wiki/Natural_methane_on_Mars" title="Natural methane on Mars">Methane</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/List_of_terrae_on_Mars" title="List of terrae on Mars">Regions</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Arabia_Terra" title="Arabia Terra">Arabia Terra</a></li> <li><a href="/wiki/Cerberus_(Mars)" title="Cerberus (Mars)">Cerberus (Mars)</a></li> <li><a href="/wiki/Cydonia_(Mars)" title="Cydonia (Mars)">Cydonia</a></li> <li><a href="/wiki/Eridania_Lake" title="Eridania Lake">Eridania Lake</a></li> <li><a href="/wiki/Iani_Chaos" title="Iani Chaos">Iani Chaos</a></li> <li><a href="/wiki/Olympia_Undae" title="Olympia Undae">Olympia Undae</a></li> <li><a href="/wiki/Planum_Australe" title="Planum Australe">Planum Australe</a></li> <li><a href="/wiki/Planum_Boreum" title="Planum Boreum">Planum Boreum</a></li> <li><a href="/wiki/List_of_quadrangles_on_Mars" title="List of quadrangles on Mars">Quadrangles</a></li> <li><a href="/wiki/Sinus_Meridiani" title="Sinus Meridiani">Sinus Meridiani</a></li> <li><a href="/wiki/Tempe_Terra" title="Tempe Terra">Tempe Terra</a></li> <li><a href="/wiki/Terra_Cimmeria" title="Terra Cimmeria">Terra Cimmeria</a></li> <li><a href="/wiki/Terra_Sabaea" title="Terra Sabaea">Terra Sabaea</a></li> <li><a href="/wiki/Tharsis" title="Tharsis">Tharsis</a></li> <li><a href="/wiki/List_of_extraterrestrial_dune_fields" title="List of extraterrestrial dune fields">Undae</a></li> <li><a href="/wiki/Mars_Polar_Lander#Landing_zone" title="Mars Polar Lander">Ultimi Scopuli</a></li> <li><a href="/wiki/Vastitas_Borealis" title="Vastitas Borealis">Vastitas Borealis</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Common_surface_features_of_Mars" title="Common surface features of Mars">Physical<br />features</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Martian_canals" title="Martian canals">"Canals"</a> (<a href="/wiki/List_of_Martian_canals" title="List of Martian canals">list</a>)</li> <li><a href="/wiki/Chasma#Mars" title="Chasma">Canyons</a></li> <li><a href="/wiki/Crater_chain" title="Crater chain">Catenae</a></li> <li><a href="/wiki/Chaos_terrain" title="Chaos terrain">Chaos terrain</a></li> <li><a href="/wiki/List_of_craters_on_Mars" title="List of craters on Mars">Craters</a></li> <li><a href="/wiki/Fossa_(planetary_nomenclature)" title="Fossa (planetary nomenclature)">Fossae</a></li> <li><a href="/wiki/Gullies_on_Mars" title="Gullies on Mars">Gullies</a></li> <li><a href="/wiki/Mensa_(geology)" title="Mensa (geology)">Mensae</a></li> <li><a href="/wiki/Planetary_nomenclature#Descriptor_terms_(feature_types)" title="Planetary nomenclature">Labyrinthi</a></li> <li><a href="/wiki/List_of_mountains_on_Mars" title="List of mountains on Mars">Mountains</a> <ul><li><a href="/wiki/List_of_mountains_on_Mars" title="List of mountains on Mars">by height</a></li></ul></li> <li><a href="/wiki/List_of_rocks_on_Mars" title="List of rocks on Mars">Observed rocks</a></li> <li><a href="/wiki/Outflow_channels" title="Outflow channels">Outflow channels</a></li> <li><a href="/wiki/List_of_plains_on_Mars" title="List of plains on Mars">Plains</a></li> <li><a href="/wiki/Valley_network_(Mars)" title="Valley network (Mars)">Valley network</a></li> <li><a href="/wiki/Vallis_(planetary_geology)" title="Vallis (planetary geology)">Valleys</a></li> <li><a href="/wiki/Gravity_of_Mars" title="Gravity of Mars">Gravity</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Geology_of_Mars" title="Geology of Mars">Geology</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Brain_terrain" title="Brain terrain">Brain terrain</a></li> <li><a href="/wiki/Carbonates_on_Mars" title="Carbonates on Mars">Carbonates</a></li> <li><a href="/wiki/List_of_areas_of_chaos_terrain_on_Mars" title="List of areas of chaos terrain on Mars">Chaos terrain</a></li> <li><a href="/wiki/Mars_surface_color" title="Mars surface color">Color</a></li> <li><a href="/wiki/Composition_of_Mars" title="Composition of Mars">Composition</a></li> <li><a href="/wiki/Concentric_crater_fill" title="Concentric crater fill">Concentric crater fill</a></li> <li><a href="/wiki/Dark_slope_streak" title="Dark slope streak">Dark slope streak</a></li> <li><a href="/wiki/Martian_dichotomy" title="Martian dichotomy">Dichotomy</a></li> <li><a href="/wiki/Fretted_terrain" title="Fretted terrain">Fretted terrain</a></li> <li><a href="/wiki/Geysers_on_Mars" title="Geysers on Mars">Geysers</a></li> <li><a href="/wiki/Glaciers_on_Mars" title="Glaciers on Mars">Glaciers</a></li> <li><a href="/wiki/Groundwater_on_Mars" title="Groundwater on Mars">Groundwater</a></li> <li><a href="/wiki/Gullies_on_Mars" title="Gullies on Mars">Gullies</a></li> <li><a href="/wiki/Lakes_on_Mars" title="Lakes on Mars">Lakes</a></li> <li><a href="/wiki/Martian_lava_tube" title="Martian lava tube">Lava tubes</a></li> <li><a href="/wiki/Lobate_debris_apron" title="Lobate debris apron">Lobate debris apron</a></li> <li><a href="/wiki/Marsquake" title="Marsquake">Marsquake</a></li> <li><a href="/wiki/Martian_meteorite" title="Martian meteorite">Meteorites</a> <ul><li><a href="/wiki/List_of_Martian_meteorites" title="List of Martian meteorites">on Earth</a></li> <li><a href="/wiki/List_of_rocks_on_Mars" title="List of rocks on Mars">on Mars</a></li></ul></li> <li><a href="/wiki/Mud_cracks_on_Mars" title="Mud cracks on Mars">Mud cracks</a></li> <li><a href="/wiki/North_Polar_Basin_(Mars)" title="North Polar Basin (Mars)">North Polar Basin</a></li> <li><a href="/wiki/Mars_ocean_theory" title="Mars ocean theory">Ocean theory</a></li> <li><a href="/wiki/Ore_resources_on_Mars" title="Ore resources on Mars">Ore resources</a></li> <li><a href="/wiki/Martian_polar_ice_caps" title="Martian polar ice caps">Polar caps</a> <ul><li><a href="/wiki/True_polar_wander_on_Mars" title="True polar wander on Mars">polar wander</a></li></ul></li> <li><a href="/wiki/Seasonal_flows_on_warm_Martian_slopes" title="Seasonal flows on warm Martian slopes">Recurring slope lineae (RSL)</a></li> <li><a href="/wiki/Ring_mold_crater" title="Ring mold crater">Ring mold craters</a></li> <li><a href="/wiki/Rootless_cone" title="Rootless cone">Rootless cones</a></li> <li><a href="/wiki/Seasonal_flows_on_warm_Martian_slopes" title="Seasonal flows on warm Martian slopes">Seasonal flows</a></li> <li><a href="/wiki/Martian_regolith" title="Martian regolith">Soil</a></li> <li><a href="/wiki/Martian_spherules" title="Martian spherules">Spherules</a></li> <li><a href="/wiki/Martian_surface" title="Martian surface">Surface</a></li> <li><a href="/wiki/Swiss_cheese_features" title="Swiss cheese features">"Swiss cheese" feature</a></li> <li><a href="/wiki/Terrain_softening" title="Terrain softening">Terrain softening</a></li> <li><a href="/wiki/Tharsis#Location_and_Size" title="Tharsis">Tharsis bulge</a></li> <li><a href="/wiki/Volcanism_on_Mars" title="Volcanism on Mars">Volcanism</a></li> <li><a href="/wiki/Water_on_Mars" title="Water on Mars">Water</a></li> <li><a href="/wiki/Yardangs_on_Mars" title="Yardangs on Mars">Yardangs</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Geological_history_of_Mars" title="Geological history of Mars">History</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Amazonian_(Mars)" title="Amazonian (Mars)">Amazonian</a></li> <li><a class="mw-selflink selflink">Hesperian</a></li> <li><a href="/wiki/Noachian" title="Noachian">Noachian</a></li> <li><a href="/wiki/History_of_Mars_observation" title="History of Mars observation">Observation history</a></li> <li><a href="/wiki/Classical_albedo_features_on_Mars" title="Classical albedo features on Mars">Classical albedo features</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Astronomy_on_Mars" title="Astronomy on Mars">Astronomy</a></th><td class="navbox-list-with-group navbox-list navbox-odd" 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:1%"><a href="/wiki/Moons_of_Mars" title="Moons of Mars">Moons</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Phobos_(moon)" title="Phobos (moon)">Phobos</a> <ul><li><a href="/wiki/Stickney_(crater)" title="Stickney (crater)">Stickney crater</a></li> <li><a href="/wiki/Limtoc" title="Limtoc">Limtoc crater</a></li> <li><a href="/wiki/Phobos_monolith" title="Phobos monolith">Monolith</a></li></ul></li> <li><a href="/wiki/Deimos_(moon)" title="Deimos (moon)">Deimos</a> <ul><li><a href="/wiki/Swift_(Deimian_crater)" title="Swift (Deimian crater)">Swift crater</a></li> <li><a href="/wiki/Voltaire_(crater)" title="Voltaire (crater)">Voltaire crater</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Astronomical_transit" title="Astronomical transit">Transits</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Solar_eclipses_on_Mars" title="Solar eclipses on Mars">Solar eclipses on Mars</a></li> <li>Satellite transits <ul><li><a href="/wiki/Transit_of_Phobos_from_Mars" title="Transit of Phobos from Mars">Phobos</a></li> <li><a href="/wiki/Transit_of_Deimos_from_Mars" title="Transit of Deimos from Mars">Deimos</a></li></ul></li> <li>Planetary transits <ul><li><a href="/wiki/Transit_of_Earth_from_Mars" title="Transit of Earth from Mars">Earth</a></li> <li><a href="/wiki/Transit_of_Mercury_from_Mars" title="Transit of Mercury from Mars">Mercury</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Asteroid" title="Asteroid">Asteroids</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Impact_events_on_Mars" title="Impact events on Mars">Impacts</a></li> <li><a href="/wiki/List_of_Mars-crossing_minor_planets" title="List of Mars-crossing minor planets">Mars-crossers</a> <ul><li><span class="nowrap"><a href="/wiki/2007_WD5" title="2007 WD5">2007 WD<span style="position: relative; top: 0.3em;"><span style="font-size:80%;">5</span></span></a></span></li></ul></li> <li><a href="/wiki/Mars_trojan" title="Mars trojan">Trojans</a> <ul><li><a href="/wiki/5261_Eureka" title="5261 Eureka">5261 Eureka</a></li> <li><span class="nowrap"><a href="/wiki/(101429)_1998_VF31" title="(101429) 1998 VF31">1998 VF<sub>31</sub></a></span></li> <li><span class="nowrap"><a href="/wiki/(121514)_1999_UJ7" title="(121514) 1999 UJ7">1999 UJ<sub>7</sub></a></span></li> <li><span class="nowrap"><a href="/wiki/(311999)_2007_NS2" title="(311999) 2007 NS2">2007 NS<sub>2</sub></a></span></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Comets</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/C/2013_A1_(Siding_Spring)" title="C/2013 A1 (Siding Spring)">C/2013 A1 (Siding Spring)</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">General</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Orbit_of_Mars" title="Orbit of Mars">Orbit</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Exploration_of_Mars" title="Exploration of Mars">Exploration</a></th><td class="navbox-list-with-group navbox-list navbox-odd" 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:1%">Concepts</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Mars_flyby" title="Mars flyby">Flyby</a></li> <li><a href="/wiki/List_of_Mars_orbiters" title="List of Mars orbiters">Orbiter</a></li> <li><a href="/wiki/Mars_landing" title="Mars landing">Landing</a></li> <li><a href="/wiki/Mars_rover" title="Mars rover">Rover</a></li> <li><a href="/wiki/Mars_sample-return_mission" title="Mars sample-return mission">Sample return</a></li> <li><a href="/wiki/Human_mission_to_Mars" title="Human mission to Mars">Human mission</a></li> <li><a href="/wiki/Mars_to_Stay" title="Mars to Stay">Permanent settlement</a></li> <li><a href="/wiki/Colonization_of_Mars" title="Colonization of Mars">Colonization</a></li> <li><a href="/wiki/Terraforming_of_Mars" title="Terraforming of Mars">Terraforming</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Template:Mars_spacecraft" title="Template:Mars spacecraft">Missions</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/List_of_missions_to_Mars" title="List of missions to Mars">List of missions to Mars</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Advocacy</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><i><a href="/wiki/The_Mars_Project" title="The Mars Project">The Mars Project</a></i></li> <li><i><a href="/wiki/The_Case_for_Mars" title="The Case for Mars">The Case for Mars</a></i></li> <li><a href="/wiki/Inspiration_Mars_Foundation" title="Inspiration Mars Foundation">Inspiration Mars Foundation</a></li> <li><a href="/wiki/Mars_Institute" title="Mars Institute">Mars Institute</a></li> <li><a href="/wiki/Mars_Society" title="Mars Society">Mars Society</a></li> <li><a href="/wiki/Mars_race" title="Mars race">Mars race</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/List_of_artificial_objects_on_Mars" title="List of artificial objects on Mars">Artificial objects on Mars</a> <ul><li><a href="/wiki/List_of_extraterrestrial_memorials#Mars" title="List of extraterrestrial memorials">Memorials on Mars</a></li></ul></li> <li><a href="/wiki/Mars_in_fiction" title="Mars in fiction">Fiction</a> <ul><li><a href="/wiki/List_of_films_set_on_Mars" title="List of films set on Mars">List of films set on Mars</a></li> <li><a href="/wiki/Martian_scientist" title="Martian scientist">Martian scientist</a></li> 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