Here's an image I posted here a few years ago, I noticed it has been reimaged by someone.

http://www.harmakhis.org/dunes/m0301600.jpg.htm

At the time I though that something might have been outgassing from the fault and eating away the bottom of the dunes. It's not clear whether the dunes are actually forming an arch over the fault in some places or whether they are just not as wide over the fault. It seems though that the dunes formed over the fault easily, so the fault may have formed after the dunes or it was full of perhaps ice at the time. Perhaps the fault, if it is a fault, widened later, the ice in it sublimated, or there was CO2 under the ground eating away at the dunes. Next is the MSSS image:

http://ida.wr.usgs.gov/html/m03016/m0301600.html

and here it is reimaged. I can't see any changes in the dunes. I would presume if the outgassing is still happening the dunes would be fragile and would have changed in places.

http://ida.wr.usgs.gov/html/r02001/r0200139.html

The only other image I've seen with dunes forming over a fault or river is this:

http://www.harmakhis.org/fluid/m0100047b.JPG.htm

I believe I named this Krupp's Fault at the time. Since Don would never admit anything was his fault at the time, I though he might admit this was his fault. :-)