Re: could be the circular pits associated with the Meridiani
"bullseye" structure are analogous to the gnammas of Australia... and the "bullseye" itself could still be analogous to Richat.
A priori determination of impact origin of depressions on Mars can hardly be considered definitive -- especially given the extraordinary diversity of circular pits and depressions on Mars and the extensive sedimentation found in Meridiani.
I guess somebody is gonna have to go down there and check!
Volunteers? ;-)
Cheers, B R Felix
