Layers in Western Arabia Terra
Layers in Western Arabia Terra
ESP_027747_1820  Science Theme: Future Exploration/Landing Sites
Extensive erosion in this region has exposed numerous rock layers. Layers are visible on the flanks of some hills and on the basement (the lowest rock unit) between the hills.

Layers exposed on the sides of hills are visible as terraced steps. The formation of these steps is a result in differences between layers in cohesion and resistance to weathering. Weaker layers disaggregate quickly into shallow slopes, while stronger layers maintain steep “sharp” appearing edges. Such contrast can occur, for example, between alternating strong lava flows and weak volcanic ash deposits.

Between the hills dark sands blow across the landscape and have accumulated in hollows created by these differences in rock strength. Since the hollows tend to follow weaker layers, they outline the layer exposure, even when the topography of the hollows are too subtle to see on its own.

Written by: Mike Mellon  (21 November 2012)

This is a stereo pair with ESP_026270_1820.
Acquisition date
27 June 2012

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
272.1 km (169.1 miles)

Original image scale range
27.6 cm/pixel (with 1 x 1 binning) so objects ~83 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
53°, with the Sun about 37° above the horizon

Solar longitude
131.0°, Northern Summer

For non-map projected images
North azimuth:  96°
Sub-solar azimuth:  27.1°
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Full resolution JP2 download
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Black & white is 5 km across; enhanced color about 1 km
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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.