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Posted by: imipak Dec 6 2008, 10:16 PM

http://www.universetoday.com/2008/12/06/stairways-on-mars-lead-to-clues-on-cyclical-moderate-climate/ article on a new Science paper, "Quasi-Periodic Bedding in the Sedimentary Rock Record of Mars" (http://www.sciencemag.org/cgi/content/abstract/322/5907/1532. ) (UT just happened to be the first write-up I came across; there's plenty of coverage elsewhere.)

Posted by: Doc Dec 6 2008, 11:29 PM

This discovery is actually quite important and I'm glad someone has started a thread about it. The formation and structure are due to martian milankovitch cycles and seem to be similar to the layers being formed at the poles. Basically one could say that this supports the hypothesis that ice used to cover the the temperate & equitorial regions of Mars.

Posted by: Doc Dec 6 2008, 11:36 PM

Evidently the discovery is also renewing debates on similar processes taking place on Earth. Here we have mostly 5:1 layers due to the the stabilising effect of the moon. The 10:1 layers on Mars are because the planet is free to wobble by a larger degree.

Posted by: CosmicRocker Dec 7 2008, 06:40 AM

This is one of the most interesting things I've read about in months. It would be nice if someone could find the HiRise stereo-pair that was described, and make some full resolution anaglyphs. This link to a http://spaceflightnow.com/news/n0812/05mro/ was passed to me via IRC.

Posted by: tdemko Dec 7 2008, 11:39 AM

This branch of geosciences is called http://en.wikipedia.org/wiki/Cyclostratigraphy. Although cycles of sedimentation related to lunar, seasonal, and sunspot cycles had long been recognized, stable isotope analyses of fossil marine critters and sediments lead to the development of our current understanding of the relationships between incoming solar radiation (http://en.wikipedia.org/wiki/Insolation) and the planetary orbital parameters of eccentricity, precession, and obliquity. The orbital-induced insolation effects are called http://en.wikipedia.org/wiki/Milankovitch_cycles, after the Serbian mathematician and engineer http://en.wikipedia.org/wiki/Milutin_Milanković who first quantitatively elucidated them. On earth, the most dramatic connection between orbitally-modulated insolation, climate, and sedimentary processes is the control of the growth and decay of continental ice sheets and the resulting sea level changes (as much as 100's m), the "http://www.sciencemag.org/cgi/content/abstract/194/4270/1121" of the Ice Ages. Of course, many more connections and teleconnections have been documented (strength of monsoons, ENSO cycles, etc.), thus the emergence of this branch of stratigraphy and related branches of geochemistry and paleoclimatology.

On modern (and geologically recent) Mars, it seems that orbitally-modulated insolation changes also must control the distribution and phase of volatiles on the surface and in the near-surface environments. As, on earth, other related climatic affects, including atmospheric circulation patterns, also vary in this beat-like fashion. We are just starting to glimpse the large-scale (here visible from orbit) physical stratigraphic evidence of these cycles. Regional and outcrop-scale mapping, along with facies and geochemical analyses will tell us much more...

Posted by: imipak Dec 7 2008, 01:02 PM

CosmicRocker - the "http://www.sciencemag.org/cgi/data/322/5907/1532/DC1/1" (PDF) includes this table, plus the layer location and thickness data:

Posted by: CosmicRocker Dec 8 2008, 12:34 AM

Thanks. The images are amazing, but while at the HiRISE site I noticed a message that said http://hirise.lpl.arizona.edu/anaglyph-teaser.php I think I'll wait for the HiRISE versions. They say they will be releasing hundreds of anaglyphs next week.

Oh, heck. I'm sure they won't mind if I post one or two ahead of time. Here is one from Becquerel at 1/16th scale.

Posted by: CosmicRocker Dec 8 2008, 05:56 AM

Here is another from Becquerel at 1/4th scale. It would be really nice if we could view anaglyphs in IAS Viewer.

Posted by: imipak Dec 8 2008, 07:41 PM

Wow, those are great, thanks CR! What a happy coincidence that science and eye-candy turn up together. (Stepping gingerly around non-UMSF http://www.google.co.uk/search?q=mars%20site%3Arealclimate.org)... any idea what sort of vertical relief we're looking here? How tall is that spectacular spire half-way down the right-hand side of your second anaglyph, I wonder?

Posted by: jekbradbury Dec 8 2008, 10:41 PM

The HiRISE website has an amazing http://www.uahirise.org/media/clips/periodic-layering-becquerel.mov of Becquerel available.

Posted by: CosmicRocker Dec 10 2008, 04:00 AM

That flyover was outstanding.

The http://hirise.lpl.arizona.edu/e has published a gallery of 362 anaglyphs of Mars' surface. They have full resolution JPEG2000 images and lower res PNGs. Best of all, like the regular imagery these can be viewed with IAS viewer.

Here's the direct link to http://hirise.lpl.arizona.edu/anaglyph/singula.php?ID=PSP_001955_2015.

Posted by: MouseOnMars Feb 1 2009, 07:31 PM

So, if I've grasped this correctly, every layer we see in those images is a warm to ice age swing happening over ten's of thousands of years ?

Posted by: tty Feb 1 2009, 09:37 PM

QUOTE (MouseOnMars @ Feb 1 2009, 08:31 PM)

Posted by: rlorenz Feb 2 2009, 01:47 AM

QUOTE (tdemko @ Dec 7 2008, 06:39 AM)