Medusa crater paleolake. The crater is about 80-km in diameter. The inflowing channels can be seen on the left of the image. The drainage basin is short. However, sedimentary terraces in the basin show that once water cover the entire floor of the crater. Playa (dry lake bed) morphologies are visible on the floor, as well as a small patch of bright material (bottom right) that could be an evaporite deposit resulting from the precipitation of salts while the lake water was evaporating.

Source: NASA