Alluvial Fan along a Crater Wall
NASA/JPL/UArizona
Alluvial Fan along a Crater Wall
PSP_003269_1600  Science Theme: Fluvial Processes
This observation covers an alluvial fan along the wall of a large crater in the mid latitudes of the Southern hemisphere of Mars.

The fan was formed when water and sediments drained down the steep wall of the crater creating a cone-shaped pile of debris at the base. As the fan grew with time, the channels carrying water and sediment across the fan surface changed locations, producing a layered deposit capped by channels radiating from the fan apex along the crater wall.

Subsequent stripping of the fan surface by the wind has left the coarser channel deposits in relief and exposed the fine scale layering within the fan in many locations. While is it is not known whether the source of the water responsible for creating the fan was related runoff from precipitation or groundwater or perhaps both, alluvial fans of broadly similar form are observed in many locations on Earth and are usually formed by runoff from precipitation.


Written by: John Grant  (25 April 2007)

This is a stereo pair with PSP_003691_1600.
 
Acquisition date
08 April 2007

Local Mars time
15:42

Latitude (centered)
-19.931°

Longitude (East)
123.180°

Spacecraft altitude
256.2 km (159.2 miles)

Original image scale range
25.9 cm/pixel (with 1 x 1 binning) so objects ~78 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection
Equirectangular

Emission angle
4.6°

Phase angle
48.6°

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

Solar longitude
215.1°, Northern Autumn

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North azimuth:  97°
Sub-solar azimuth:  2.3°
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POSTSCRIPT
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.