on the surface and beneath the surface of Mars for eons. There is much evidence that fluids are operating at and beneath the surface today. There ought to be conglomerates of some sort, and we ought to have seen evidence of them, and maybe we have. The problem -- as you have pointed out -- is one of paradigms.

One can only observe what fits within ones paradigm, whether it be "White Mars" or "Warm and Wet Mars" or always "Dry and Cold Mars" -- or whatever. What's actually there MUST fit a paradigm, or be made to fit one, or it is ignored.

So that's part of why I say that if there are fossils on Mars, we have probably already seen them, and yet cannot recognize them 1) because we have nothing to compare them with to "prove" they are fossils; 2) no generally accepted paradigm of Mars allows for fossils to be discovered without enormous effort (deep drilling, in situ mircroscopic examination, discovery of remnants of single-cell creatures...).

It's only been recently that serious work has been done to find out how fluids (especially water) would actually behave under simulated Mars conditions, and there is still no paradigm which accommodates the results. We are still in a Twilight Zone where water is the only widely considered fluid (though signs point to a very different fluid environment of acids and so forth) and its behavior on the surface of Mars is confidently and erroneously asserted to be either "instant freeze" or "instant sublimation." Well, it ain't true, but that doesn't matter. Since the actual behavior of water at the surface of Mars doesn't fit anywhere in the standard models, the acutal behavior is ignored (except in the most arcane literature). Further complicating the situation is the fact that water isn't even the most likely surface fluid, now or over time. While liquid CO2 is unlikely, other fluids are highly likely, including sulfuric acid, sulfur dioxide, and forms of lava and mudflows that may be very unfamiliar to geologists.

A good deal of the most interesting stuff at both the Opportunity and the Spirit sites isn't competent rock at all, but some sort of deposit, presumably salts/sulfate, presumably precipitated from a fluid. How it happened is only beginning to be explored, maybe through hot springs or shallow seas or whatever, at the surface or subsurface, who knows? Whatever the case, it doesn't meet expectations. It doesn't fit the paradigm.

Conglomerates? Well, sure. But someone will always come along and say, "Not so!" and that's fine. Just got to make sure the observations and the challenges keep coming and that paradigms shift in light of observations, not that observations be forced to fit prevailing models.