Beautiful pictures of Mars from Nasa 5

A "fossa" is a cavity or depression in the surface. Floods of water and lava are thought to have emanated from the larger fossae nearby, perhaps forming the channel and later filling it with lava.

Read more: http://science.time.com/2012/08/06/martian-vistas-a-look-at-curiosity-rovers-new-home/#ixzz2HGvgF7ws