{ "title": "Hardened Dunes in Arcadia Planitia", "authors": "HiRISE", "metadata": { "thumbnailURL": "https://static.uahirise.org/anews/2021-02-04/ESP_038143_2205.jpg", "excerpt": "Evidence indicates that the dunes have become hardened into cohesive sediment or even into sandstone rock." }, "version": "1.5", "identifier": "ESP_038143_2205", "language": "en", "layout": { "columns": 10, "width": 1024, "margin": 85, "gutter": 20 }, "documentStyle": { "backgroundColor": "#faf7f2" }, "components": [ { "role": "heading1", "layout": "heading1Layout", "text": "HiPOD: 4 February 2021" }, { "role": "divider", "layout": "bigDividerLayout", "stroke": { "width": 3, "color": "#8c2028" } }, { "role": "title", "layout": "halfMarginBelowLayout", "text": "Hardened Dunes in Arcadia Planitia" }, { "role": "photo", "layout": "fullBleedLayout", "caption": "Less than 1 km across. (NASA/JPL/UArizona)", "URL": "https://static.uahirise.org/anews/2021-02-04/ESP_038143_2205.jpg" }, { "role": "body", "format": "html", "layout": "hipodMarginLayout", "text": "


This image in Arcadia Planitia shows dunes in a crater. Unlike active dunes on the planet, those here are bright, and, zooming in, there are several lines of evidence indicating that the dunes have become indurated, that is, hardened into cohesive sediment or even into sandstone rock. For example, the dune field at the southern edge is cut off by a step cliff, indicating erosion of hard material. Although fine scale ripples on the original dune surface are preserved, we also see large scale fluting from southwest to northeast, a common texture associated with wind-induced sand abrasion.

How these dunes became indurated is unknown. One possibility is that this area of Mars was buried and then exhumed, a process that seems to have occurred many times in the Martian past over various areas of the planet. During burial, compaction and possibly ground water circulation would have indurated the dunes, leaving them as a hard sandstone that, when exhumed, was subsequently partially eroded.

" }, { "role": "photo", "layout": "fullBleedLayout", "caption": "Evidence indicates that the dunes have become hardened into cohesive sediment or even into sandstone rock. (NASA/JPL/UArizona)", "URL": "https://static.uahirise.org/anews/2021-02-04/ESP_038143_2205-2.jpg" }, { "role": "body", "format": "html", "layout": "hipodMarginLayout", "text": "

ID: ESP_038143_2205
date: 15 September 2014
altitude: 299 km (186 mi)

NASA/JPL/UArizona

" }, { "role": "caption", "format": "html", "layout": "halfMarginBothLayout", "text": "Enhanced color image is less than 1 km across; black and white is less than 5 km. For full images with scalebars, see the above ID link to our website.

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