This HiRISE image shows a large ice mound located in Louth Crater. At 70 degrees North, this is the lowest latitude permanent deposit of water ice on Mars.
The HiRISE image, taken in early summer, shows details of the mound and non-ice portions of the crater floor. The mound is characterized by rough textures and layering similar to features seen on the north polar layered deposits near the Martian North Pole. Zooming in to
an area in the southeast part of the mound, dark sinuous ridges are apparent.
These may be the crests of partially defrosted dark sand dunes or perhaps some other feature that we do not understand. This is the only area on Louth where these enigmatic ridges are found.
Written by: Nathan Bridges (4 August 2010)
More info and image formats at http://hirise.lpl.arizona.edu/ESP_018301_2505
Image: NASA/JPL/University of Arizona