...trouble is, it isn't the "geology" we hoped!

We've learned a lot about weathering processes on Mars - that rinds form on rocks with some hints of aqueous activity, yet olivine dust is widespread. We've learned that breccias do not form on Mars like they do on the moon. We've learned that Opportunity has hit real paydirt, while Spirit is in a less favourable location, but we could have anticipated this in advance (some of us did).

What we've learned from Opportunity has opened a whole new phase of Martian geology studies - areology if you will. It is showing a planet behaving in a different way than our Earth, in ways we did not entirely anticipate and still don't fully understand. The implications are significant for life beyond the Earth, for our own origins, and for the future of planetary exploration and resource exploitation.

There will be a huge surge in sulphate studies over the next few years that will lead in a decade or so to much better understanding of the real geology pf Mars, IMHO, rather than that of Earth, hopefully transplanted to other worlds.

And the rovers are still rolling, and still finding more data.

But, for what it's worth, I don't expect that the Columbia Hills will magically reveal deeper buried units. They are just a gentle upwarping of the same rocks that floor Gusev crater. We went to the wrong place, where the lake basin (if there ever were a lake) is too ancient, and we knew this before we went, but chose to take a risk.

Oh, and having read your article, I'm mildly appalled at the inane comments that you're quoting. I don't have room here for a detailed critique, but Squyres, for instance, is repeateing many of the fallacious arguments of Christensen and others about the Meridiani deposits.

to whit:

We have no clear evidence that Eagle crater is stratigraphically close to the top of the sequence, nor that Endurance crater is any way close to its base. I would view both as being somewhere in the middle unless and until we gain evidence to the contrary from proper and detailed geologic mapping of the deposits .

None of these craters is big enough to have penetrated the observed "several hundred metres" thickness of the Meridiani deposits, and indeed, we need to rework that analysis now that we understand the haematite to be a lag deposit, and not the primary material.

I also continue to doubt the existence of a lake of any significance, and firmly suggest that a sabkha model is a better way to understand a regional-scale terrain-draping non-basinal deposit.

ANyway, my main point was to refute the suggestion that what we are seeing is not "geology". It is very much geology, on Mars. it isn't what some people sold us, and are still trying to sell us. The trick is to stop listening to the salesmen and to read the fine print of the rocks...