Hi all,
I thought this was interesting enough to carry over from another thread that had become derailed.
Navy writes:
I've heard about these ice sheets. My source said the layers were due to weather related events, not annual deposites. For example, storm, thaw, snow, storm, long thaw, lil storm..etc. I also, in a unrelated article read of a WWII plane squadren that was burried in 50 ft of ice. Since these layers are only an inch or so in depth, annual deposites doesn't seem to make sense, and as a method of dating, irrelevent.
I'll lay it all out again as it's a new thread.
There ARE annual bands that can be divided into summer & winter layers in the Greenland ice cores. We know this because we observe them being deposited. The summer layer is characterised by being more airy & layered. This is due to snowfall followed by frosting followed by more snow etc. In the summer days when temperatures are higher & the air can hold more moisture the snow sublimates into vapour. At night it falls to the ground as frost, known locally as
hoar, this is a phenomenon that occurs rarely in winter due to the low temperature. As such the winter band is much more homogenous. Eventually due to pressure the air gets squeezed out (not entirely) & or forms a clathrate with the ice as it becomes deeper.
There are a number of other phenomena that correlates to the higher level banding that allows the layers to be tracked in deeper ice even when the ice is entirely homogenous (which only occurs rarely in any case).
1/ Oxygen isotopes. Stable isotopes of oxygen (mostly Oxygen-16,17, & 18) preferentially precipitate depending on temperature. As such a summer/winter rise & fall of isotope ratios can be observed (& is observed in recently deposited bands).
2/ Conductivity. Summer snow contains more acid impurities that reduce the conductivity of the ice. As such rising & falling cycles can be observed (& is observed in recently deposited bands).
3/ Hydrogen Peroxide. The summer levels of sunlight produce more H2O2 than winter, which is reflected in the banded layers.
4/ Beryllium-10 isotope. Be-10 is formed in the atmosphere & corelates to the level of cosmic rays the sun outputs. This varies with the 11-year sunspot cycle, plus the 1700 "Maunder minimum" (when sunspots were rare). The Be-10 falls to the surface & can thus be measured in the ice cores. 11 year Be-10 blips are observed.
5/ Correlation with known events. Predicted high levels of acid precipitation & therefore anomolous low conductivity are correlated with known eruptions, eg Laki, Hekla, Katla, Eldgja (Icelandic eruptions), Vesuvius (79AD), & Mt St. Helens (1479AD), among others.
6/ Correlation of the above with other dating methods associated with the determining of climate change. Radiometric dating of bogs etc. & the banding seen of cold/warm climate species/pollens show excellent correlation with the ice core interpretations & inferred global temperature changes. In short all methods agree when the ice ages took place.
There are in the order of 110,000 banded layers in the Greenland ice cores. Given the overwhelming correlation for the banding being able to be correlated with annual precipitation patterns I maintain that the ice core record refutes a YEC timeline.
Appendix: Regarding the age old creationist "refutation" of ice core dating, namely buried WWII aircraft in many layers of snow. Firstly the aircraft were buried in an area of Greenland that has the highest snowfall in the country. Most glaciers move in the order of a foot or two per year, the region in which the aircraft were uncovered has glaciers moving
miles per year, commensurate with the level of snowfall. Secondly, creationists seem surprised that there are many layers, ie more than 50-ish. This is because individual heavy snowfalls can form their own narrow layers, & this can also be seen in the summer ice core record. The difference is that there is a homogenous layer between the airy summer
layers. Ergo a WWII aircraft buried deeply in many layers of snow is not a refutation. What
would be a refutation is having >> 50-60 airy/homogenous layers that display the correlations 1-4 above.
But they
don't.
Ref:
The Two Mile Time Machine - Ice Cores, Abrubt Climate Change, & Our Future by Richard B. Alley 2000. ISBN 0-691-00493-5
Mark
"Physical Reality of Matchette’s EVOLUTIONARY zero-atom-unit in a transcendental c/e illusion" - Brad McFall
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