Basal Exposure of South Polar Layered Deposits
Basal Exposure of South Polar Layered Deposits
PSP_004311_1050  Science Theme: Polar Geology


This full HiRISE image shows layers exposed on the scarp that bounds the south polar layered deposits. These deposits make up a geologic unit of layered water ice, containing a small amount of dust. The different ice layers are thought to record varying climatic conditions in the history of Mars, in much the same way that layers within ice-sheets on the Earth can tell us about how our own climate has changed.

The top of this scarp is near the top/left of the image and is about 800 meters (half a mile) above the bottom, although only the lower 560 meters (1840 feet) is shown here. Near the bottom of the scarp, the icy layers have a disrupted, irregular appearance. This irregular wavy appearance may have been caused by the flow of ice at some point, although it is currently too cold on Mars for significant flow to be occurring today.

Layers near the top of the image appear to be converging and some of the lower layers appear truncated. Geologists call this an unconformity, as it indicates that there was a previous episode of erosion that removed material down to the truncated layers. Subsequent deposition then built this stack of ice back up to its current thickness. Features like this, as well as the layers themselves, can help planetary scientists figure out what past climates on Mars may have been like.

Written by: Shane Byrne (via Nathan Bridges)  (25 July 2007)

This is a stereo pair with PSP_004720_1050.
Acquisition date
28 June 2007

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
248.5 km (154.4 miles)

Original image scale range
25.1 cm/pixel (with 1 x 1 binning) so objects ~75 cm across are resolved

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25 cm/pixel

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Emission angle

Phase angle

Solar incidence angle
57°, with the Sun about 33° above the horizon

Solar longitude
266.2°, Northern Autumn

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North azimuth:  103°
Sub-solar azimuth:  40.0°
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All of the images produced by HiRISE and accessible on this site are within the public domain: there are no restrictions on their usage by anyone in the public, including news or science organizations. We do ask for a credit line where possible:

NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate, Washington. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona.