{ "title": "Reading the Rock Record at Nili Fossae", "authors": "HiRISE", "metadata": { "thumbnailURL": "https://static.uahirise.org/anews/2020-05-21/PSP_010206_1975.jpg", "excerpt": "This image captures a record of changing environments on ancient Mars, as recorded in the rock record at Nili Fossae." }, "version": "1.5", "identifier": "PSP_010206_1975", "language": "en", "layout": { "columns": 10, "width": 1024, "margin": 85, "gutter": 20 }, "documentStyle": { "backgroundColor": "#faf7f2" }, "components": [ { "role": "heading1", "layout": "heading1Layout", "text": "HiPOD: 21 MAY 2020" }, { "role": "divider", "layout": "bigDividerLayout", "stroke": { "width": 3, "color": "#8c2028" } }, { "role": "title", "layout": "halfMarginBelowLayout", "text": "Reading the Rock Record at Nili Fossae" }, { "role": "photo", "layout": "fullBleedLayout", "caption": "The southern part of the full observation. Less than 5 km across. (NASA/JPL/UArizona)", "URL": "https://static.uahirise.org/anews/2020-05-21/PSP_010206_1975.jpg" }, { "role": "body", "format": "html", "layout": "hipodMarginLayout", "text": "
This image captures a record of changing environments on ancient Mars, as recorded in the rock record at Nili Fossae.
Part of our image shows a rock type known as megabreccia, composed of numerous differently colored blocks, each up to 40 meters across, arranged in a seemingly disorganized array. Megabreccia forms when an energetic event, such as formation of an impact crater, breaks up pre-existing rocks and jumbles their fragments. Megabreccia is found in some of the most ancient rocks exposed on the Martian surface.
Elsewhere in the image are layered rocks, which have been shown by the orbiting spectrometers OMEGA and CRISM to contain clay minerals. These minerals must have formed in the presence of water, and may have later been transported and deposited here in sedimentary layers. Most of the layers appear to overlie the exposures of megabreccia, but some megabreccia blocks are themselves internally layered, suggesting that sedimentary processes were active here early in Martian history.
ID: PSP_010206_1975
date: 28 September 2008
altitude: 280 km
NASA/JPL/UArizona