... Fossilized remains of underground cracks suggest water flowed beneath martian surface . ... A 3-D image of an impact crater in the Nilosyrtis area on the martian surface shows long pipe-like ridges, fossilized evidence of ancient subsurface water flow. ... Networks of narrow ridges found in impact craters on Mars appear to be the fossilized remnants of underground cracks through which water once flowed, according to a new analysis by researchers from Brown University. ...