otseng wrote:micatala wrote:Keep in mind that, given the dating on some of the Antarctic cores, we would need an average of 4 or 5 layers or more per year for many tens of thousands of years to get a date down to even close to the 100,000 year window you postulate for the flood.
As far as precipition levels, I am not sure it is fair to say that only Greenland has sufficient precipitation to form discernible layers. Obviously there are many thousands of feet of ice over land areas in the Antarctic. How did all of it get there without being precipitated?
Let's first determine the average thickness of the ice cap on Antarctica.
"About 98% of Antarctica is covered by ice, which averages at least 1.6 kilometres (1.0 mi) in thickness."
http://en.wikipedia.org/wiki/Antarctica
"The average thickness of the ice sheet is about 2,200 metres."
http://www.kidcyber.com.au/topics/Antarctic.htm
We'll take the higher number, 2200 m.
Now, let's determine the average precipitation.
"In the interior of the continent the average annual precipitation (in *equivalent of water) is only about 50 mm (about 2 in), less than the Sahara. Along the coast, this increases, but is still only about 200 mm (8 in) in *equivalent of water."
CoolAntarctica.com
We'll take the lower number, 5 cm. (Water and ice do not have the same densities. But, their densities are not too far different, perhaps around 10% difference.)
So, 5 cm per year to accumulate 2200 meter would take around 44,000 years. So, given a constant rate that is the same as todays, the upper limit would be 44,000 years to deposit the entire Antarctica ice cap. So, it is well within the time range that I claim for the flood.
This is a good ball park calculation to do.
However, the previously cited link on the
Kohnen Station ice core has more specific data, so we can do better.
The site has an ice thickness of 3,309 plus or minus 22 m; the current drilling depth is 3,190 m, of which 3,139 m has been analysed for a wide range of constituents. The current mean annual surface temperature is -54.5 °C, and the snow accumulation rate is 25 kg m-2 yr-1 (2.5 cm water equivalent per year).
So, the current annual snowfall is half of your assumption in water equivalent and the thickness is 50% more. Based on this, keeping everthing else the same, we get 132,360 years.
So, even without considering the actual layers, if we do assume current snowfall averages can be extrapolated into the distance past, we are well over 100,000 years.
We still haven't been given any real reason to doubt the layer count yet. We have what I would consider a plausible suggestion that multiple layers can form, but not observational data to back this up.
I would say it is also just as plausible to suggest there are years when no layer forms. Especially given the paucity of precipitation alluded to by otseng, what would happen if the average of 2.5cm/year included some years where there were 0 cm? Would a layer form and if not, would we be able to determine that a year was "skipped?"
So, it seems just on thickness of the ice sheets alone, we have reason to believe, but I would allow less than solid proof, that the ice sheet is at least 130,000 years old.
We have layers which give even stronger evidence, as we do not need to assume conditions today are similar to those in the distant past, that the sheets are 500,000 years old or older.
We have no evidence, only a plausible suggestion, that the sheets could be as young as 40,000 years old ( or perhaps younger if you alter the ballpark assumptions).
One other question. Does the ball park calculation take into account the incredible compression that the lower layers are under? Could the water in these layers actually be significantly denser than water at atmospheric pressure? If so, this pushes the 130,000 year figure even higher.
And as one other possible factor, is it possible the lower layers have been extruded? In other words, could the pressure lead to the layers being spread out? Obviously this would require the volume, even under density, have some place to go. However, this seems plausible as ice calves off or melts off the edges of the ice sheet. Over time and very slowly, it might be that a section ice that originally took up 10 square cm ends up taking up 20 or 40 square cm at depth. This would have the effect of diminishing the 2.5 cm/year figure to half or a quarter of that, at least for the lower layers.
The question would be whether the underlying geographical configuration would allow the layers to be extruded out of the are where this particular core was taken and either have the volume accumulate in some other area, or migrate to the edge of the sheet. We would also want to take into account the possiblity of the opposite phenomenon. Namely, that ice volume in the layers was pushed INTO the area where the core was taken from.
" . . . the line separating good and evil passes, not through states, nor between classes, nor between political parties either, but right through every human heart . . . ." Alexander Solzhenitsyn
