You come up with the coolest pictures, Greg! Thanks for digging this one up.

IMHO - if there had been glaciation in two directions I would think that the older markings would be mostly obliterated by the newer ones; these look almost identical (in prominenece, at least) in each direction to me. Also, I can't quite see how glaciation could produce such long, wide gouges in such straight lines - these are fairly large scale images I would think. Do you have scale information, Greg?

Nick, would blowing dust form such evenly parallel lines across terrain? And wouldn't there be some blurring at the intersection of lins?

To my eye, one set of lines seems to be of a different texture than the other - those running from bottom left to top right look more like gouges, while the other set look like deposits. Or maybe it's just the light angle.

My guess is similar to Splinx's - fracture lines from two different impacts.

Or the fossilized remains of a large, scaly organism. :)

A guarantee - we will learn many amazing, totally unexpected things when we finally set foot there. (guess that's pretty safe, eh?)