Among many fascinating aspects...
Is that the layers we see at the surface in Meridiani precisely mirror the layered deposits at immensely larger scales found in craters all over the planet, most famously "White Rock", but in many, many other places, too. An example:
Nick's notion of ooze from below, without standing water/battery acid, may be spot on. But imagine the scale of it to provide the deposits we see in Meridiani and the craters. Is there anything comparable on Earth?
And what is the implication for near-surface water/battery acid now or in the past? How recently, in other words, might some of these deposits have formed?
Myself, I suspect not recently at all...