[X] My Assistant

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I hope that this is posted in the correct area; if not, please move it to the most appropriate location.

I am struck by the fact that the layers in rocks at both Gusev & Meridiani are astonishingly regular in thickness. This is even more remarkable given the fact that the Home Plate deposits are thought to be volcanic instead of sedimentary (in a hydrological sense); yet the regularity persists.

Can anyone account for this perception? I realize that many non-mutually-dependent processes may be at work here, but overall it is striking that nearly all layered rocks to date have apparently almost equal layer thickness distributions (within a given example), and this periodicity is puzzling. Perhaps we are finally seeing evidence of highly regular climatic cycles al la Mikhailovitch?

This may well be my personal observational bias at work; still, sure would appreciate a reality check!

[Shaka]

Миланковић? Milankovic? Milankovitch?
Assuming that there isn't another Serbian astronomer, named "Mikhailovitch", who calculated the eccentricity, axial tilt, and precession cycles for Mars, I assume you are referring to the earth cycles by the former Serb
Milankovitch Cycles.
The earth climatic cycles have periods of about 100,000, 41,000 and 23,000 years (see link), and they can show up as sedimentological changes at those intervals, but the layering we have been examining close-up from the rovers on Mars have been attributed to processes that would 'normally' occur in a more rapid interval. In particular, the Meridiani layering reflects the migration of ancient sand dunes past a particular point. We have a very limited grasp of what actual time periods that involves, and the rates of movement could well change in response to longer-term Mars cycles "a la Milankovitch", but I doubt we have yet examined large enough sections to try and detect such 'coarse' patterns. Dune movement would probably remain more-or-less constant, to the extent that wind velocities in the region did so.
The PIs' story at the moment for the Home Plate layering may reflect series of volcanic eruptions rather than dune mobility, and, again, we are probably dealing with shorter-term processes than the Milankovitch type cycles. Volcanism would seem less likely to march to a Milankovitch drumbeat than are atmospheric activities.

(I wonder if either of us are less confused now than 10 minutes ago?)