Numerous gullies that have formed along the southwestern wall of
an elongated shaped pit are visible in this image. This pit is located within a degraded 100 kilometer impact crater in the southern polar region of Mars.
Gullies originate along the rubbly, bouldery upper wall region and have eroded into the numerous layered wall units before terminating in fan deposits on the pit floor ( see close-up image ). A previous HiRISE image ( ESP_020956_1115 ) of this location taken during the spring showed frost and interesting dark-toned flows within the gully channels. Neither frost nor dark flows are apparent in this summer-time image.
One goal of HiRISE is to repeat observations at locations such as this to detect changes that may lead to understanding how these gullies form.
Written by: Ginny Gulick (22 June 2011)
More info and image formats at http://hirise.lpl.arizona.edu/ESP_022156_1115
Image: NASA/JPL/University of Arizona