re: North polar geysers?
Correction. I just reread the poster Dana Johnson on Markcarey.com/mars/ who produced this blown up image and I can't say his observations are wrong:
North polar geysers?
http://www.marsroverblog.com/discuss--north-polar-geysers.html
In post #5 in that thread he noticed the deposits on both sides of the dunes are fan shaped. The ones on the sides that I called "round" are just more compact and not as blown out by the wind. This is probably because of the wind direction. Both sides seem to originate from a point source at the crests of the dunes.
He argues it is due to a liquid flow but I can't confirm this.
Bob Clark