i.e.: a Speculative Structural Model of "Homeplate"
(That's a cross-section.)
Folded strata have been observed in the Columbia Hills. Is Homeplate a structural basin that has been eroded into what is known in the biz as "topographic inversion"?
The eolean deposits on home plate may include those funky salts we've seen.
The strata is probably igneous. Did you see that nice example of a vesiculated rock a while back?
A run around homeplate, getting an idea of the orientation of the strata on several sides, would be a good test o' the model.