Tubes in High Resolution Image

The tube of another type in PSP_006268_1995.

hirise.lpl.arizona.edu/PSP_006268_1995

I'd say this seems like a clear case of a hypothesis falsified by the evidence. Maybe geologists can tell us more but the "tubes" appear to be some type of flowing waves of water or mud that was "quick frozen" at some point. The ice crystals look like the inside of a refrigerator icebox when the defroster doesnt work [Neil]

I vaguely remember reading something about "crusty sand dunes" or something like that (some rough equivalent), but I'm not really sure.

rd