APOD,
The picturres posted on the HiRise site are often extraordinary, but they are never seen on APOD. Which is a pity, as the captions attached to many are almost as extraordinary - for being boring. Sometimes they are so detached that it seems the captions are describing a different picture.
For instance this picture:
http://hirise.lpl.arizona.edu/PSP_008982_1965
shows a crater floor with enormous black barchan dunes marching across it. The caption ignores these entirely, and discusses "layered deposits" that are "of particular interest because these materials are not likely to be related to the impact event, but rather post-impact infill of the crater. Modification of the deposits has now revealed layers of material."
Scream! What about the dunes? They are amazing, bigger than any Earthly dune (?) and BLACK. Only a geologist (areologist?)with tunnel vision could forebear to comment on them!
JOhn