Louth Crater (CTX Frame- Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)

This HiRISE image shows a large Ice Mound located in Louth Crater. At 70° North (in the Region of Vastitas Borealis), 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 South-Eastern part of the Mound (see the following EDMs), dark Sinuous Ridges appear.
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.