Gullies and Curved Ridges at the Base of Crater Walls
NASA/JPL/University of Arizona
Gullies and Curved Ridges at the Base of Crater Walls
ESP_023328_1325  Science Theme: Glacial/Periglacial Processes
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This Southern mid-latitude crater is typical of other small craters in this latitude band, containing both gullies on its walls and arcuate ridges at the base of the walls.

These features appear inter-related and their orientation on the crater wall can be associated with the latitude of the crater. Craters at latitudes between about -30 and -44 degrees (in the Southern hemisphere) typically have pole-facing gullies and curved ridges. Craters at latitudes between -44 degrees and -60 degrees (as is this one at -47 degrees) typically have these features on equator-facing walls, or on the east and west walls. This is thought to relate to changes in the obliquity of Mars.

These features likely formed during a period of high obliquity (tens of millions of years ago). During this time, it is thought that snowfall was deposited in these mid-latitude regions, and the high tilt of the planet led to higher degrees of solar insolation on the different crater walls, causing the snow to melt and form gullies. The arcuate ridges are thought to be moraines, or remnants of snowpacked ice flowing down the crater wall and onto the crater floor.

Written by: Dan Berman   (28 September 2011)

This is a stereo pair with ESP_023750_1325.

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Acquisition date
19 July 2011

Local Mars time:
14:18

Latitude (centered)
-47.390°

Longitude (East)
37.603°

Range to target site
251.1 km (156.9 miles)

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

Map projected scale
25 cm/pixel and North is up

Map projection
Equirectangular

Emission angle:
0.5°

Phase angle:
46.1°

Solar incidence angle
46°, with the Sun about 44° above the horizon

Solar longitude
330.5°, Northern Winter

North azimuth:
97°

Sub-solar azimuth:
44.3°
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Postscript
For information about NASA and agency programs on the Web, visit: http://www.nasa.gov. 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. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona. The image data were processed using the U.S. Geological Survey’s ISIS3 software.