Skip to comments.Milankovitch Cycles Indistinguishable from Randomness (another Evo dating method bites the dust)
Posted on 06/02/2009 10:41:12 AM PDT by GodGunsGuts
June 2, 2009 A claim has often been made by geologists that the rock sediments record cyclical changes in Earths orbit. Milankovitch cycles, named for the man who analyzed them, are a set of regular periodic changes to the orbital eccentricy, obliquity, and axial precession. Such subtle changes, it is alleged, produce climate change and sea level elevations. The climate forcing, in turn, produces periodic differences in thickness of sedimentary layers. The search for Milankovitch signatures in rock records has been used as a method of dating sediments.
Geologists at Virginia State and Virginia Polytechnic tested this hypothesis with computer models. They specifically encoded Milankovitch-like cycles in the production of sediments. The layering produced was indistinguishable from randomness, according to their report in the Journal of Geology. Here was their conclusion:
(Excerpt) Read more at creationsafaris.com ...
For more on the various problems with Milankovitch Cycles, see Milankovitch Cycles And the Age of the Earth:
Variations in the Earth's eccentricity, axial tilt, and precession comprise the three dominant cycles, collectively known as the Milankovitch Cycles
And geologists do what?
The coming and going of periods of Great Glaciation over the last 2 million years (all 20 of them) are in sync with these cycles.
The direct linkage is not well understood.
“Real rock successions are very likely to have been historically more complex than our simulations governed by merely a few basic parameters. This poses a challenge to even most cleverly designed quantitative methods used to test for stratigraphic patterns, with their statistical outcomes being inherently ambiguous: does a given outcome indicate that the record was not formed in a cyclic fashion, or does it merely reflect the fact that an original cyclic driver has been masked by the complexity of depositional processes?”
In a nutshell the authors indicate that they lack the mathematical sophistication in their model to properly obtain any statistical certitude.
Why would M cycles show up in sedimentary rock layers? I’m not aware glaciation or the lack thereof can be detected in sedimentary layers.
We have two earlier “Snowball Earth” episodes. One of them is over a billion years ago, and another one is something like 600,000,000 years ago. What happens is the glaciers wear down rocks, turn them into gravel, and then dump them off the edge of the continental shelves into great heaping piles of stuff, all neatly layered, and then welded together with “crap”.
It sounds like that kind of record would not reveal shorter term cycles, like what we've seen over the last million years or so of around 100,000 years.
I’m always a little suspicious when computer models are used to “test” theories based on physical observation.
Somehow I think it should be the other way around.
Thanks for the ping!
You pick up the very large "climate signals" by looking for vast layers of gravel embedded in limestone or shale.
Fish crap, to be precise.
Absolutely ~ PLUS, anything else that can fall to the bottom of the ocean. Our own contribution to the definition of “crap” will be, of course, monumentally huge!
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.