Eroding Mesas Forming Seif and Barchan Dunes
NASA/JPL/University of Arizona

Eroding Mesas Forming Seif and Barchan Dunes
PSP_007676_1385  Science Theme: Aeolian Processes


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This observation shows sand dunes within the Hellespontus region of Mars.

The sand appears to come from the layered mesas and knobs, features that have been eroded by powerful winds. The dunes here have a morphology indicating formative winds blowing from east to west (from right to left).

The primary indicator for this is the orientation of the barchan dunes, a dune type that on Earth has its horns in the downwind direction. Also, the steepest faces of the dunes are on the dunes’ eastern side, indicating easterly winds.

In addition to the barchans, some of the dunes are organized into a “seif,”, or longitudinal, form whereby their long axis is parallel to the wind. These are seen emanating from the sand sheets next to the mesas and knobs, as well as from some barchan horns.

Written by: Circe Verba, Nathan Bridges   (18 April 2008)

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Acquisition date:16 March 2008 Local Mars time: 3:09 PM
Latitude (centered):-41.407° Longitude (East):44.587°
Range to target site:256.9 km (160.6 miles)Original image scale range:51.4 cm/pixel (with 2 x 2 binning) so objects ~154 cm across are resolved
Map projected scale:50 cm/pixel and North is upMap projection:Equirectangular
Emission angle:6.7° Phase angle:69.7°
Solar incidence angle:74°, with the Sun about 16° above the horizon Solar longitude:45.8°, Northern Spring
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North azimuth:97° Sub-solar azimuth:49.8°
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North azimuth:270°Sub solar azimuth:222.4°

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