Spectacular Gullies Near Gorgonum Chaos
NASA/JPL/University of Arizona
Spectacular Gullies Near Gorgonum Chaos
PSP_003583_1425  Science Theme: Fluvial Processes
Spanish 

This image shows incredible details of a crater with gullies that provides strong evidence for gully formation involving fluid flow.

What is interesting is the variety of gully morphologies along the crater walls. The north and west walls have gullies, while the south wall has only landslides. "Mass wasting" is the more general term geologists use to describe landslides, slumps, and other movements of the ground in response to gravity. It usually occurs on steep slopes when the force of gravity causes weak or loose material to travel downslope. Mass wasting produces structures that are sometimes similar to gully channels, but which can usually be distinguished by their occurrence
on steep slopes.

The gullies on the north wall have eroded all the way to the crater rim. They appear older than other nearby gullies because they have existed long enough to be modified by permafrost processes as evidenced by the polgyonal fractures found on some of the channel and inter-gully walls. Another noticeable difference among the gullies is channel lengths. The gullies on the north wall and the group just to the left of these have much shorter channels than the gullies on the northwest wall. It is possible that the gullies with shorter channels had less fluid flow through their systems. The gullies appear to originate around a sequence of rocky layers near the crater rim.

Many of the gully channels appear to have boulders littered in many places. This suggests a fluid flowing in these channels; a fluid would preferentially transport smaller particles and leave behind the larger ones, such as the boulders visible here. There are also many small channels in each gully. These indicate multiple flow events such that some channels experience flow, then are abandoned.

The closeup image also shows several channels merging. Particularly interesting is the channel flowing from the top of the scene. There are several intertwining channels that merge into one just to the right of the center of the subimage. However, the way some channels truncate others suggests that there were at least three episodes of flow through this area.

Written by: Kelly Kolb   (15 June 2007)

This is a stereo pair with ESP_011969_1425.

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Acquisition date
02 May 2007

Local Mars time:
15:32

Latitude (centered)
-37.112°

Longitude (East)
191.903°

Range to target site
257.0 km (160.6 miles)

Original image scale range
25.7 cm/pixel (with 1 x 1 binning) so objects ~77 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection
Equirectangular

Emission angle:
9.4°

Phase angle:
58.9°

Solar incidence angle
50°, with the Sun about 40° above the horizon

Solar longitude
230.3°, Northern Autumn

North azimuth:
96°

Sub-solar azimuth:
10.8°
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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.