This image shows a portion of the floor in Palos Crater. The floor appears bumpy with high-standing layered knobs. Most of the terrain on the floor is weathering into meter-size polygonal blocks. The circular structures in the image, many of which are filled with darker aeolian material, are eroded impact craters.
Palos Crater is breached in the south by the 180 kilometers-long Tinto Vallis. Water transported along Tinto Vallis could have could have collected into Palos Crater to form a lake that later drained to the north. Sediments carried by Tinto Vallis would have also been deposited within Palos Crater so the layered unit we see along the floor today could represent these fluvial sediments.
Written by: Cathy Weitz (31 March 2010)
This is a stereo pair with ESP_017721_1775 .
More info and image formats at http://hirise.lpl.arizona.edu/ESP_016943_1775
Image: NASA/JPL/University of Arizona