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Saturday, June 16, 2007

Can Tree Rings be used for dating?

Tree ring dating (dendrochronology)

Tree ring dating (dendrochronology) has been used in an attempt to extend the calibration of carbon-14 dating earlier than historical records allow, but this depends on temporal placement of fragments of wood (from long-dead trees) using carbon-14 dating.

by Don Batten, Ph.D.

Tree ring dating (dendrochronology) has been used in an attempt to extend the calibration of carbon-14 dating earlier than historical records allow. The oldest living trees, such as the Bristlecone Pines (Pinus longaeva) of the White Mountains of Eastern California, were dated in 1957 by counting tree rings at 4,723 years old. This would mean they pre-dated the Flood which occurred around 4,350 years ago, taking a straightforward approach to Biblical chronology.

However, when the interpretation of scientific data contradicts the true history of the world as revealed in the Bible, then it’s the interpretation of the data that is at fault. It’s important to remember that we have limited data, and new discoveries have often overturned previous ‘hard facts’.

Recent research on seasonal effects on tree rings in other trees in the same genus, the plantation pine Pinus radiata, has revealed that up to five rings per year can be produced and extra rings are often indistinguishable, even under the microscope, from annual rings. As a tree physiologist I would say that evidence of false rings in any woody tree species would cast doubt on claims that any particular species has never in the past produced false rings. Evidence from within the same genus surely counts much more strongly against such a notion. Creationists have shown that the Biblical kind is usually larger than the ‘species’ and in many cases even larger than the ’genus’ — see my article Ligers and wholphins? What next?.

Considering that the immediate post-Flood world would have been wetter with less contrasting seasons until the Ice Age waned (see Q&A: Ice Age), many extra growth rings would have been produced in the Bristlecone pines (even though extra rings are not produced today because of the seasonal extremes). Taking this into account would bring the age of the oldest living Bristlecone Pine into the post-Flood era.

Claimed older tree ring chronologies depend on the cross-matching of tree ring patterns of pieces of dead wood found near living trees. This procedure depends on temporal placement of fragments of wood using carbon-14 (14C) dating, assuming straight-line extrapolation backwards of the carbon dating. Having placed the fragment of wood approximately using the 14C data, a matching tree-ring pattern is sought with wood that has a part with overlapping 14C age and that also extends to a younger age. A tree ring pattern that matches is found close to where the carbon ‘dates’ are the same. And so the tree-ring sequence is extended from the living trees backwards.

Now superficially this sounds fairly reasonable. However, it is a circular process. It assumes that it is approximately correct to linearly extrapolate the carbon ‘clock’ backwards. There are good reasons for doubting this. The closer one gets back to the Flood the more inaccurate the linear extrapolation of the carbon clock would become, perhaps radically so. Conventional carbon-14 dating assumes that the system has been in equilibrium for tens or hundreds of thousands of years, and that 14C is thoroughly mixed in the atmosphere. However, the Flood buried large quantities of organic matter containing the common carbon isotope, 12C, so the 14C/12C ratio would rise after the Flood, because 14C is produced from nitrogen, not carbon. These factors mean that early post-Flood wood would look older than it really is and the ‘carbon clock’ is not linear in this period (see The Creation Answers Book, chapter 4).

The biggest problem with the process is that ring patterns are not unique. There are many points in a given sequence where a sequence from a new piece of wood match well (note that even two trees growing next to each other will not have identical growth ring patterns). Yamaguchi1 recognized that ring pattern matches are not unique. The best match (using statistical tests) is often rejected in favour of a less exact match because the best match is deemed to be ‘incorrect’ (particularly if it is too far away from the carbon-14 ‘age’). So the carbon ‘date’ is used to constrain just which match is acceptable. Consequently, the calibration is a circular process and the tree ring chronology extension is also a circular process that is dependent on assumptions about the carbon dating system.2

The extended tree ring chronologies are far from absolute, in spite of the popular hype. To illustrate this we only have to consider the publication and subsequent withdrawal of two European tree-ring chronologies. According to David Rohl,3 the Sweet Track chronology from Southwest England was ‘re-measured’ when it did not agree with the published dendrochronology from Northern Ireland (Belfast). Also, the construction of a detailed sequence from southern Germany was abandoned in deference to the Belfast chronology, even though the authors of the German study had been confident of its accuracy until the Belfast one was published. It is clear that dendrochronology is not a clear-cut, objective dating method despite the extravagant claims of some of its advocates.

Conclusion

Extended tree ring chronology is not an independent confirmation/calibration of carbon dating earlier than historically validated dates, as has been claimed.

References

  1. Yamaguchi, D.K., Interpretation of cross-correlation between tree-ring series. Tree Ring Bulletin 46:47–54, 1986.
  2. Newgrosh, B., Living with radiocarbon dates: a response to Mike Baillie. Journal of the Ancient Chronology Forum 5:59–67, 1992.
  3. Rohl, David, A Test of Time, Arrow Books, London, Appendix C, 1996.

~~~~~~~

I want to mention that there are plenty of other treatises on tree ring dating and they all mention one important point - trees can produce multiple rings in one year's time, just as ice can produce several layers within one season. Therefore, merely counting the rings (or the ice layers) and then simplistically announcing an age for the tree or ages for the layers is very dumbed-down science indeed!

My teenaged daughter knows that if she turns the key on the car, it starts, and if she puts it in gear and presses on the gas pedal, it goes! She has no idea of the inner workings of the automobile. We know, in fact, that there are transmissions and gears, there are controlled explosions and pistons and valves and rings and cams and electric impulses and all sorts of operations involved in a four-cycle internal combustion engine and automatic transmission doing the job of making a car move down the road.

Counting tree rings and then assigning that number as an age for that tree is as simplistic and ignorant as claiming that an automobile is powered by a key and a foot.

7 comments:

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Lava said...

A bit of spam in the comments recently...


I'm no scientist. So, like radar, I'll just point any other readers to another article.

http://razd.evcforum.net/dendrochronology.html

enjoy.

Anonymous said...

Excellent link, Lava.

"Counting tree rings and then assigning that number as an age for that tree is as simplistic and ignorant as claiming that an automobile is powered by a key and a foot."

And of course this is not what scientists do, Radar. Is that really the best argument you could make - something you made up entirely from scratch and based on nothing but your own willful ignorance? Because your (rather unconvincing and minor) point is thoroughly taken apart at the link Lava provided, as is the entirety of Don Batten's essay.

I take it you'll do anything but try to honestly address the points made by Paul Smith.

-- creeper

radar said...

Paul Smith also knows that species and genus and family are labels that are descriptors but are not the same as a biblical "kind." He spends a great deal of time going over differences in the type of tree that he considers important, while both Batten and myself would consider them to be immaterial.

Batten and I would both agree that a Collie and a Wolf are not the same animal, but they are the same kind of animal and similarities may well be compared. In this case, it is more like a Collie and a Labrador Retriever.

Batten is upfront about his presuppositions and Smith should be as upfront about his. He makes several claims in his post about ages of trees and ages proved by dendrochronolgy but doesn't support the claims with evidences. He knows that it is difficult-to-impossible to accurately characterize tree rings as real or false once we get beyond fairly recent recorded history because we have no historical markers or meteorological records to allow us to look for a "missing summer" or be sure that in one year 5-6-7 rings might have been produced.

In point of fact, from what we can determine from tree rings, it is incredibly simplistic to count 4800 rings and then assign an age of 4800 years. Many types of trees with 4800 years will be 3600 years old or even younger.

While Smith claims a continuous ongoing dendrochronology regarding the European Oak. But in actual years, how long have they been studied and by what means are the rings produced before specific recorded history being compared to any kind of data whatever?

Batten and Smith have given us a "he said, she said" dialogue. Since Patten's comes from a science-oriented website and Smith's from an opinion page apparently run by him, I think I will stick with Batten.

Anonymous said...

"Paul Smith also knows that species and genus and family are labels that are descriptors but are not the same as a biblical "kind." He spends a great deal of time going over differences in the type of tree that he considers important, while both Batten and myself would consider them to be immaterial."

1. So how are these two different plants classified according to biblical "kinds"? If "creation science" has nothing of value to offer on this front, then why bring it up? The point is that the plants are different, and that Batten did not see fit to make his point by using an appropriate comparison, which weakens his argument.

2. Looks like you completely missed the important element of this part of his argument: "What is certain is that he is comparing a very distantly related, very different coastal species to two high altitude species and saying it is the same - a species that grows in an entirely {different habitat\ecology}. Perhaps he intentionally chose a species cultivated for rapid growth (for the timber industry), living in an entirely different seasonal growth environment where he can intentionally take samples from trees that are known to frequently have false rings."

Why not compare apples and apples?


"He knows that it is difficult-to-impossible to accurately characterize tree rings as real or false once we get beyond fairly recent recorded history because we have no historical markers or meteorological records to allow us to look for a "missing summer" or be sure that in one year 5-6-7 rings might have been produced."

If only a single species in a single location were examined, then maybe you might have a point... BUT it looks like you skipped over or simply ignored the fact that the data was verified using data from different tree species on different continents. Here is the salient quote once again, just to make sure you don't miss it this time: "This "issue" of false rings and missing rings also would mean that there should be noticeable differences between the two different Bristlecone Pines, the European Oaks and the German Pines, for there is no reason for these trees to have same pattern of climate with age if the cause of the patterns seen is false and missing rings."

Again: "[...] there is no reason for these trees to have same pattern of climate with age if the cause of the patterns seen is false and missing rings."

Radar, if you disagree with that, could you explain your reasoning?

"In point of fact, from what we can determine from tree rings, it is incredibly simplistic to count 4800 rings and then assign an age of 4800 years. Many types of trees with 4800 years will be 3600 years old or even younger."

1. As was clearly pointed out to you more than once, this is not what scientists do. (Is there a reason why you're choosing to ignore this point?)

2. Not only that, but this line of argument completely ignores that this works in both directions, i.e. that not only can there be more than one line per year, it is also possible to skip years. Without additional specific data, it is not possible to simply assume that these aberrations will work in favor of a young Earth.

If "creation scientists" have come up with detailed studies on this subject that provide any coherent explanation (i.e. not just vague attempts to cast doubt on mainstream science) from a YEC perspective, by all means present it.

3. Re. "Many types of trees with 4800 years will be 3600 years old or even younger" - which types of trees with 4800 years will be 3600 years old or even younger? Can you be specific and let us know what you are basing your statement on?


"While Smith claims a continuous ongoing dendrochronology regarding the European Oak. But in actual years, how long have they been studied and by what means are the rings produced before specific recorded history being compared to any kind of data whatever?"

1. I'm not sure how long the study of European Oak dendrochronology has been going on. Why do you consider this significant?

2. By what means are the rings produced? Any simple introduction to dendrochronology would have that answer for you. Different growth rates according to season, that kind of thing.

"Batten and Smith have given us a "he said, she said" dialogue."

No, Batten presented an argument, and Smith exposed the arguments to be false - which you are pointedly choosing not to argue against. Which is why I'm highlighting the points again here.

"Since Patten's comes from a science-oriented website and Smith's from an opinion page apparently run by him, I think I will stick with Batten."

... which is a clear example of the "appeal to authority" fallacy. And I guess a weak attempt to avoid this whole area, which isn't working out all that great for you.

-- creeper

radar said...

Creeper, I pointed out that the differences in trees is not significant to a creationist since both are apparently the same "kind."

I also am trying to make the point that dendrochronology is making assumptions that I disagree with, assumptions that you do not even address. You gloss them over as if they were established scientific fact, whereas the assumptions are just that; assumptions.

The European Oak project is less than 100 years old and so they are captive to the same set of assumptions. Note that I am posting more on this matter in the posts above.

Anonymous said...

"Creeper, I pointed out that the differences in trees is not significant to a creationist since both are apparently the same "kind.""

That "kind" being what?

"Tree"?

Are you suggesting that all "trees" share exactly the same characteristics with respect to tree rings, regardless of their specific composition and environment?

I'll put aside the specific language that seems to bother you so much (even though so-called "creation science" seems to offer little to no alternative as regards the biblical classification of flora) and rephrase the argument you insist on ignoring like this:

"What is certain is that he is comparing a very distantly related, very different coastal [type] to two high altitude [types] and saying it is the same - a [type] that grows in an entirely {different habitat\ecology}. Perhaps he intentionally chose a [type] cultivated for rapid growth (for the timber industry), living in an entirely different seasonal growth environment where he can intentionally take samples from trees that are known to frequently have false rings."

Can you see how such different types of plants growing in such different types of environment would have different characteristics?

I also am trying to make the point that dendrochronology is making assumptions that I disagree with, assumptions that you do not even address."

I did address you disagreeing with those assumptions (though you failed to explain on what basis you disagreed with them...) and address them again here, as follows:

1. The creationist stance of denying the mainstream classification system offers nothing in terms of knowledge about plants. It simply and willfully denies existing knowledge and replaces it with... nothing.

2. You focus on the use of the word "species" but completely sidestep the thrust of the argument. I repeated it above minus the offensive language ("species") so that hopefully you can grasp it.


"You gloss them over as if they were established scientific fact, whereas the assumptions are just that; assumptions."

On the contrary, I put the specific wording of "species" aside and focused on the essential point that was made: that we are talking about different types of trees in different environments, and that the one Batten chose appeared selected to produce the outcome he desired. Batten is welcome to make his points regarding multiple tree rings in a year using the actual tree type and environment in question. If his argument is as solid as you think it is, it would be easy to demonstrate just that using a similar tree type and environment.

"The European Oak project is less than 100 years old and so they are captive to the same set of assumptions."

Would those pesky assumptions that you refer to differ in any way from the assumptions on which the scientific progress of the past century that we currently enjoy is based?

Or are you just saying that this project doesn't start with the a priori assumption that the entire Bible is literally true?

"Note that I am posting more on this matter in the posts above."

You've posted more on radiometric dating a few days ago, but not, as far as I can see, anything that contributes to the subject of this particular discussion.

-- creeper

P.S. To this point I stand thoroughly confirmed that you will do anything but try to honestly address the points made by Paul Smith.

P.P.S.: Questions you pointedly avoided in your response:

1. How are these two different plants classified according to biblical "kinds"?

2. "[...] there is no reason for these trees to have same pattern of climate with age if the cause of the patterns seen is false and missing rings."

Radar, if you disagree with that, could you explain your reasoning?

3. "In point of fact, from what we can determine from tree rings, it is incredibly simplistic to count 4800 rings and then assign an age of 4800 years. Many types of trees with 4800 years will be 3600 years old or even younger."

As was clearly pointed out to you more than once, this is not what scientists do. (Is there a reason why you're choosing to ignore this point?)

4. Not only that, but this line of argument completely ignores that this works in both directions, i.e. that not only can there be more than one line per year, it is also possible to skip years. Without additional specific data, it is not possible to simply assume that these aberrations will work in favor of a young Earth.

If "creation scientists" have come up with detailed studies on this subject that provide any coherent explanation (i.e. not just vague attempts to cast doubt on mainstream science) from a YEC perspective, by all means present it.

5. Re. "Many types of trees with 4800 years will be 3600 years old or even younger" - which types of trees with 4800 years will be 3600 years old or even younger? Can you be specific and let us know what you are basing your statement on?

And I'll take it you concede that your "appeal to authority" fallacy was a dud.