HiRISE: Ridges in Eridania basin

Eridania Basin, located at the head of Ma’adim Vallis, has mounting geomorphic and spectral evidence that it may have been the site of an ancient inland sea. This site presents interesting mineralogical and geological evidence for the past existence of a large aqueous system on Mars that could have been long lived, and may have been well suited for ancient life, and almost certainly contains important clues about the ancient climate… [More at link]