Unfortunately, we are still dealing with an entirely catastrophic model for circular formations on Mars and the rest of the planetary bodies. Yet catastrophe-impact is one of the possible mechanisms for their formation, not the only one.

In this case, a depression has long been recognized in the Meridiani plain. Its origin has not been well understood, although given the extent and the relative shallowness of the Meridiani depression, an "origin" as such (as opposed to topographic/geologic unevenness) seemed somewhat irrelevant.

Now comes a possible circularity to part of the depression, and very vague indications of a multi-ring structure, and of course the catastrophists are right on it claiming it's an impact structure! Well, maybe not. Seems to me they did the same thing to "explain" the Vastitas Borealis, Northern Plains depression.

I submit that impact is invoked way too often to account for this or that circular formation on Mars and other bodies, and that alternate explanations (such as internal forces, and in the case of Meridiani especially, hot springs and other forms of upwelling) should be more thoroughly investigated.

And in the case of Mars, we might do well to investigate whether giant basins can form at the surface from the actions of interior material.

Impact has certainly left its mark on Mars, but it's not the only thing...

Cheers, Happy New Year

BRFelix