This may be largely a repeat of what grumpy has written, but I will also respond to this post by otseng.
otseng wrote:micatala wrote:I think any inconsistency is due to there being two ( or maybe more) uses of the word "layers" that has been occurring.
This could be the case. And if so, ambiguous terminology leads to confusion and possibly even incorrect conclusions. (If an annual layer is not a single layer, then perhaps it should be referred to as an "annual layer-set" to avoid ambiguity.)
However, I'm not fully convinced that an annual layer means multiple layers. Several sources alludes to an annual layer that is comprised of one light and one dark band that corresponds to the seasons.
Counting the annual layers based on visual appearance (summer layers are often darker due to more dust content or ice that has melted and then refrozen)
http://www.gns.cri.nz/iceandsnow/about_icecores.html
One year of snow accumulation can be seen in the core as a couplet of a light-colored ice layer and a thinner, darker colored layer.
http://www2.umaine.edu/USITASE/teachers/icecores.html
A slightly darker layer that contains dust blown onto the ice sheet during summer, when not much new snow falls, marks each year's new ice. The winter layer consists of cleaner and lighter-colored ice.
http://www.k5geosource.org/content/dd/climate/pg6.html
I allow I may have been somewhat ambiguous in my language, and this is partly due to my learning things as we have been going through the thread.
Yes, as I have said before, it is possible to detect annual layers by visual inspection, at least for some ice cores. I would also allow that in some ice cores or snow pits you might be able to visually detect subannual layers.
It seems to me you are denying that one can tell the difference between the subannual layers and the annual layers. I believe scientists have no problem making this distinction, as I will explain again below.
otseng wrote:In fact, the Don Linday site linked to here says the following:
So, now we have a way to answer the basic question: how many layers per year? And the answer turns out to be: one. To be more precise, it is thought that in the last 50,000 years, the deviation from 1:1 is much less than 1%. That is, the best possible count to layer 50,000 would mis-date by much less than 500 years.
The oxygen ratio isn't the only method used to draw that conclusion. The deuterium ratio follows the same pattern. And then there's the ratio of Beryllium 10 to Beryllium 9. This is a little different, because Be10 comes from the upper atmosphere, not from the ocean. And, one cycle of this ratio represents a Solar sunspot cycle, which is to say, 11 years.
Note he refers to the oxygen ratio I alluded to above. There is also an 11 year Beryllium cycle against which the oxygen cylce can be checked.
Note that these two methods employ completely different mechanisms! The first depends on seasonal variations in temperature. The second on the solar sunspot cycle which is independent, at least largely so, of the temperature cycle.
The way I read it, Don Lindsay states that a single layer corresponds to a single year. As for Be10 dating, we can start looking into that.
Again, I believe Lindsay is taking into account that we can discern between annual and subannual layers.
Now, the question of course is, if we define annual layers in this way, can we distinguish between subannual layers and annual layers?
I think we can rule out visual determination.
I don't believe this is a valid conclusion. This only follows if you cannot tell the difference between subannual and annual layers. I would accept that it might be difficult in some cases to determine annual layers visually. However, you are ignoring that visual inspection is backed up by multiple other mechanisms, many of which have been discussed at length in the thread.
otseng wrote:
It is evidently possible in at least some places and at some depths for trained observers to tell which layers are annual and which are not. I have provided evidence that scientists have been making observations of how layers form going back to at least the 1950's.
I believe you are referring to this:
http://iahs.info/redbooks/a054/054023.pdf
Now, this is in China in at a glacier where melting occurs. They seem to be looking at a number of features of the glacier including how the ice forms and how it moves. They are not, that I can see, checking to see if dating techniques are detecting annual layers accurately as they are marking the layers as they form with a thin layer of sawdust.
However, it does show scientists, and this is in the 1950's, doing "as they form" observations of layers.
http://debatingchristianity.com/forum/v ... 629#263629
The location and conditions are different from where ice core dating takes place, so this article does not have much relevance to ice core dating. In particular, melting would invalidate ice core dating techniques. As for distinguishing between a subannual layer and an annual layer-set, I could not find in the article exactly what is the procedure.
You missed the point, even though I did try to make it explicit. Remember that you had challenged my claim that scientists had used observations of ice layers as they form to back up their counting of annual layers. I noted that scientists would have to be pretty dim-witted not to use this obvious check, but I went the extra mile to look for examples where they had done real-time observations of the formation of ice layers. The China example is an example where scientists have observed and kept track of the layers as they form.
I specifically allowed that in this case there is no indication they checked these layers against visual or other dating methods, but the point stands that they did make the observations of the layers as they formed.
And
here is an excerpt from a book, authored by Crary and Mellor, on snow and ice studies. This page specifically mentions observations in the Antarctica of ice layers as they form in regions where melting may occur. The page discusses the Ross ice shelf.
Prior to this article, I had thought that melting never occurs in the Antarctic. But it states "Melting in this area of Antarctica was observed only during a few abnormally warm days during the summer season 1957-1958". And it discusses ice layers forming by meltwater refreezing.
True enough, but again, this does not invalidate the point I was making.
We also have other non-visual methods of determining where the dividing lines between annual layers are. As I alluded to above, these include comparisons of O16 and O18 oxygen isotopes. There are also other chemical methods that we could perhaps go into in more detail.
We can start looking at that too.
We have already started. I've alluded to this several times already and noted that this method can be used even when visual layers are not discernible. I also noted this has been used to validate other methods.
We have also presented evidence that scientists can and have checked their methods for counting annual layers with "marker events" in the record like volcanic eruptions, the onset of the industrial revolution, known past changes in climate (e.g. the Little Ice Age), etc. If their methods of counting layers was actually counting snowfall events and their were many layers per year, these checks would be way off. They seem not to be so it is fair to say their methods seem to be at least fairly accurate.
As for marker events for those things that we can conclusively prove the dating for, it would be a valid dating technique. However, most of the events are during human history.
For now, let's assume we did only have marker events during human history. This would still not invalidate my point. If our counting of layers is valid during recorded human history, say 3 or 4 thousand years, this is an incredible validation of the technique and does allow us to apply it further back in time with some confidence.
In essence, what we have done is taken a yard stick that we want to check for validity. We put up a six inch ruler that we know is correct next to the first six inches of the yard stick and they match. We used the same mechanism to create the last 30 inches of the yardstick as we used for the first six. Is it not reasonable to have some confidence that the yardstick is correct all the way down?
I will allow this is not conclusive proof, but I would say it is clearly quite unreasonable to assume the ice layer counting technique, having been validated within small margins of error back say 4000 years, should be considered completely unreliable past that date, especially when the appearance and chemistry of the layers behaves very similarly after that point as before.
I would say absolutely not. We can tell, at least in some circumstances, which layers are annual and which are not.
Well, I acknowledge that if there was only one snowfall event in one year, then a layer would be annual. My point is that a single layer is not an artifact of summer/winter change, but a layer is a result of a snowfall event.
This continues to ignore that we can discern in many cases between annual layers and snowfall event layers. Even if this were not possible visually, it is possible by other means.
Also, can we agree the annual layers are NOT determined solely by visual inspection but by multiple and often independent mechanisms?
We can start investigating those other mechanisms.
Again, I understand you may not have time to investigate every post and especially every link in every post. However, you seem to be assuming we have not already considered other mechanisms already, and we have in fact been discussing other mechanisms for several pages.
otseng wrote:FInally, can we also agree that if scientists are correctly determining the annual layers, this pushes the date for any hypothesized flood back at least several hundred thousand years?
If ice core dating is true with the measurement of hundreds of thousands of years, it would not be in the timeline I claim for the flood.
Just to clarify what "it" means, I am assuming you are agreeing that if the ice core dating is true or at least not off by more than 20%, then no global flood occurred within some hundreds of thousands of years. I was admittedly not specific in my date, but scientists have claimed ice cores going back more than half a million years so we might use 500,000 as a fairly firm estimate.
As a final comment, I think we could clarify what happens in situations where there is melting. However, I will note that the cores which give the oldest dates are from areas where melting certainly does not happen now and indications are has not happened for hundreds of thousands of years. Thus, I don't think investigating areas where melting DOES occur periodically or even annually will invalidate the larger point of examining the ice cores in the first place, which was to prove beyond reasonable doubt that this one line of evidence by itself proves no global flood happened within several hundred thousand years.
" . . . 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
