The Argyre impact basin contains some ancient eroded terrains, exposing rocks with diverse compositions, as shown by the color variability.
These are windows into ancient Mars, which was a wetter world than Mars today.
Written by: Alfred McEwen (3 February 2011)
More info and image formats at http://hirise.lpl.arizona.edu/ESP_020799_1385
Image: NASA/JPL/University of Arizona
