Eroding Layers in Melas Chasma
Eroding Layers in Melas Chasma
PSP_004054_1675  Science Theme: Geologic Contacts/Stratigraphy
This image shows a mound of tilted, layered rocks exposed on the floor of Melas Chasma, the widest segment of the Valles Marineris canyon system. The portion shown above is roughly 1.6 kilometers (1 mile) wide.

At the bottom of the image is a fairly smooth surface that exposes rock layers. From this perspective, the layers have a folded appearance. Short, bright ridges superposed on top of the rock layers are likely dunes or ripples composed of wind-blown particles.

The smooth surface ends at an abrupt north-facing cliff. In the shadows of the cliff walls, more rock layers can be seen in cross section. Erosion by the wind has carved alcoves into the cliff face, from which dark fans of eroded material extend downslope to the north.

The materials making up the layers in Melas Chasma and other parts of Valles Marineris may be sediment laid down by winds or water, perhaps in ancient lakes. Alternatively, they may be layers of volcanic ash. HiRISE images are providing new insight into their origin by revealing the layer structures at unprecedented scale.

Written by: James Wray  (10 October 2007)
Acquisition date
08 June 2007

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
265.0 km (164.7 miles)

Original image scale range
26.5 cm/pixel (with 1 x 1 binning) so objects ~80 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
47°, with the Sun about 43° above the horizon

Solar longitude
253.5°, Northern Autumn

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  343.7°
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Merged IRB
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Black and white
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non-map           (544MB)

IRB color
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non-map           (416MB)

Merged IRB
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Merged RGB
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RGB color
non map           (400MB)
B&W label
Color label
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EDR products

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RGB: red-green-blue
About color products (PDF)

Black & white is 5 km across; enhanced color about 1 km
For scale, use JPEG/JP2 black & white map-projected images

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.