Mamers Valles is a long (approximately 1000 kilometers) sinuous canyon beginning in Arabia Terra and ending in the Northern lowlands of Deuteronilus Mensae. This image features the southern facing slope of the canyon wall.
The northern half (top) has a rough, pitted texture with numerous impact craters, while the middle section shows the steep canyon wall. Streaks of slightly different colors show slope material eroding onto the canyon floor. Though the canyon itself was formed long ago, the material deposited on the canyon floor has been laid down over time, creating a much younger surface. [More at link]