geocreationism.com

One of the main criticisms that Young Earth Creationists (YECs) lobby against Old Earth Creationists (OECs) is that scientific methods of aging ancient rocks and fossils are unreliable.  Therefore, the reasoning goes, don’t rely on it.  In fact, if you are trying to age anything you think is older than 10,000 years old, don’t even try.  After all, according to scripture, nothing was around back then.  If you try using methods that suggest ages older than 10,000 years old, your findings will be filled with contradictions and inconsistencies, so do not be surprised when you find them.  You can try reconciling them, but don’t bother.  After all, if you already know the earth is younger than 10,000 years old, then what do you gain trying explain why two different techniques are off by 100 million years?

Now, I must clarify that if the earth is young, then the above line of reasoning is quite logical and reasonable.  If the earth is young.  The problem is that we do not really know from scripture that the earth is young, and I have explained several reasons why on this blog (Biblical Difficulties for a Young Earth - Part 1, Biblical Difficulties for a Young Earth - Part 2: Not so easy for a child to understand, and Biblical Difficulties for a Young Earth - Part 3: The sun is not in the sky).  However, besides explaining why I find the YEC position problematic, I believe I have a responsibility to seriously consider the YEC’s arguments against my own views.

In Effect of Zircon Discovery on other Early-Earth Theories, I wrote about the scientific evidence for geological conditions that completely match the Genesis account of what conditions were on Day 1 (the earth was formless and void, covered in water and darkness, waters above connected to waters below, no celestial bodies visible). The primary discovery on my part was a 2001 research article on how the discovery of zircon crystals might change our understanding of earth’s early history before 3.9 billion years ago.  I had never heard of zircon crystals before, and was thrilled when they explained why scripture’s description of the earth was correct. For similar reasons, I was also quite surprised when I happened on this 1995 article criticising the use of zircon crystals in aging the earth: http://www.answersingenesis.org/creation/v18/i1/earth.asp.  Hmmm… that article was 6 years before the study I cited.  “Uh oh,” I thought to myself, “was my 2001 citation just a repackaging of junk science from 1986? I hope not.”   If it was, then I would come clean about it; but if not?  Well, I purchased the article and read it… several times.  What I found confirmed what I already believed about how many YECs discard science.

Before I go on, I want to say that writing these kinds of blog posts is slightly distasteful to me, because I feel like I am simply bashing my fellow Christians.  That is not my intention.  I hope merely to show in this post that the scientific method is not used as haphazardly as YECs would have you think.

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Alexander R. Williams opened the answersingenesis.com article with the following:

In 1986 the world’s leading science journal, Nature, announced that the most ancient rock crystals on earth, according to isotope dating methods, are 4.3 billion years old and come from Jack Hills in Western Australia.

W. Compston and R.T. Pidgeon (Nature 321:766–769, 1986) obtained 140 zircon crystals from a single rock unit and subjected them to uranium/uranium Concordia (U/U) and uranium/thorium Concordia (U/Th) dating methods. One crystal showed a U/U date of 4.3 billion years, and the authors therefore claimed it to be the oldest rock crystal yet discovered.

A serious problem here is that all 140 crystals from the same rock unit gave statistically valid information about that rock unit. No statistician could ever condone a method which selected one value and discarded all the other 139. In fact, the other 139 crystals show such a confusion of information that a statistician could only conclude that no sensible dates could be extracted from the data.

Where to begin.

As I said before, I purchased a copy of the 1986 article, to see why the researchers would discard 139 of the 140 crystals they had in hand.  What I found was the following: 

…one zircon registers the exceptionally old age of 4,276 +- 6 Myr, which is, moreover, a minimum estimate for its original age; 16 other grains may have the same age or may be slightly younger.

The article then proceeds to describe the characteristics of the 17 old crystals, and how they compare to the overall lot of 140 crystals found.  It turns out that the 17 crystals were quite unique compared to the other 123.  Therefore, the 17 old crystals were likely all the same age as the oldest one found.

The 207Pb/206Pb ages that exceed 3,900 Myr belong to a much older population which may have had a single original age close to 4,300 Myr and have undergone early as well as recent Pb loss, or it may be a mixed-age population that formed during discrete events over an extended time period from 4,100 to 4,300 Myr ago.

Okay, so here we see the researchers in fact singled out 17 crystals, based on the fact that their chosen aging method showed them to be much older than the others.  They then determined that the oldest of them was probably the minimum age of all 17.  In other words, all 17 of them were most likely 4.3 billion years old, as determined from the age of the oldest one.  The question then is whether researchers’ line of reason is sound.  I believe it was.

First question to answer: why wouldn’t all of the zircons be the same age?  After all, they were all found together.  The answer to that turns out to be that zircons are pretty tough.

As their host rocks melt under magmatic conditions, the hard-to-melt yet buoyant zircons float up to the top of the magma, where they become part of new rocks.  As the new rocks form new zircons, they join the older ones which are there already.  According to the various age ranges of the zircons found, this type of cycle must therefore have happened several time.  Is this a logical proposition?  Is it possible that rocks would be melted, reform new rocks, then be melted again and again back when these zircons appear to have formed?  Well, according to the moon that is exactly what happened.  

The moon’s surface craters record catastrophic meteoric activity up until 3.9 billion years ago.  Given the quantity  and size of these craters, the earth most likely was impacted as well.  Such impacts would carry so much energy as to blow away the atmosphere, and melt the earth’s crust.  This is consistent with the scenario suggested by finding multiply aged zircon crystals.

So then, it turns out that the discovery of multiply-aged zircons is consistent with other scientific theories.  This means that singling out the 17 oldest zircons does not constitute ignoring the data in other 123, but rather focusing on a particular era of several that are recorded.

The next question is, why are there groups of zircons that seems close in age, but not quite identical?  And is the computed age a maximum age or a minimum?

The aging technique for zircons is based on the decay rate of Uranium isotopes.  Different Uranium isotopes decay into different Lead (Pb) isotopes at different rates.  U235 decays into Pb207, with a half life of 700 million years; U238 decays into Pb206, with a half life of 4 billion years.  Now, an actual half-life is based on the probably of decay, which means that decay is actually happening all along.  However, because the zircons would start with neither of these Lead isotopes, you can reliably take their ratio (referred to by Mr. Williams as U/U dating) and determine a possible age for old the crystal is.  This does make a big assumption however, which is that all of the Lead ever formed in the crystal is still there.

4.3 billion years is an awfully long time, and abrasion and corrosion both wear down the earth, including its mountains and its crust.  For zircons, it means that after Uranium has decomposed into Lead, some of it could be lost due to natural forces.  The result of losing lead over time would most likely result in a decrease of Pb207 (its shorter half-life makes it much more plentiful) versus Pb206, hence making the crystal appear younger than it is.  If Mr. Williams were to ask his statistician the odds of a 4 billion year old zircon crystal NOT losing any lead over time, the statistician would have to place those odds as being fairly low.  It would seem then that not only did we find zircon crystals that that were not dated to the exact same time, that fact was quite predictable, scientifically speaking.

This begs another question: how reasonable is it to believe that zircon crystals do in fact lose their lead over time?  Well, it turns out many of the samples were rounded on their edges, suggesting wear.  Others have lost their cores, suggesting wear.  The less compromised crystals appear to have older ages.  In other words, there is a correlation between apparent Lead loss, and potential causes for it.

What to conclude?  Well, it means that all of the crystals are older than U/U aging suggests.  It suggests that crystals that are close in age and proximity, and have similar characteristics are likely to have been formed together, then started losing little bits of Lead here and there as it transformed from Uranium.  It suggests that te oldest of the old is likely the minimum age for all 17 old crystals.  Far from ignoring the other crystals, this conclusion requires analyzing all of the others.  In fact, the ages of all 140 had to be understood in conjunction with phenomena suggested by the moon (the meteor strikes) in order to establish the potential conditions for the zircon formation in general.

Based on such a methodical processing of the data, I consider it irresponsible for a critic to dismiss research results so easily.  However, it doesn’t stop there.  Mr. Williams continues his article:

A further problem is that the 4.3 billion-year-old zircon, dated according to the U/U method, was identified by the U/Th method to be undatable. An unbiased observer would be forced to admit that this contradiction prevents any conclusion as to the age of the crystal. But these authors reached their conclusion by ignoring the contradictory data! If a scientist in any other field did this he would never be allowed to publish it. Yet here we have it condoned by the top scientific journal in the world.

Now, I read the entire article, and I had think about it for a while to see where the researchers were ignoring the “undatability” of the zircons suggested by U/Th methods.  However, I can see where he got it now.

In addition to looking at the ratio of Lead isotopes produced from Uranium isotopes, the researchers also looked at the ratios of Pb208 to Th232 and Pb207 to U235.  The Pb208 to Th232 ratio is the U/Th method that Mr. Williams is referring to.  Now, if there were no loss of Lead isotopes over time, then both of these dating methods should in theory give the same date that the U/U method predicts.  Furthermore, in normal cases, while U/U dating gives minimum ages, U/Th dating gives a maximum age.  Well, in this case, while the majority of U/Th samples predict dates that cluster around the same ages as the U/U aging, there are some samples (of the 140 total) that predict ages going all the way to an age of zero.  Despite all of the ages suggesting 4.1 billion years or older, the minimum of 4.1 billion and zero is zero.  To Mr. Williams, this means the crystals are undatable.  However, to make his statement, Mr. Williams needed to ignore the fact that most of the dates predicted by U/Th match most of the ages predicted by U/U. The proper conclusion then, when you find so much commonality accompanied by such discrepancy is that these discrepancies must have a cause.  And in fact, to the 1986 researchers, it was further proof that the zircons had been losing lead isotopes.  In fact, far from explaining why U/Th dating is no good, they were explaining why the anomalies the U/Th dating have same explanation as the anomalies of the U/U dating… where two different scientific anomalies are explainable by the same physical phenomenon, it is seen as evidence for that phenomenon.  For Mr. Williams however, it is proof that scientists ignore their data and then write papers explaining why they did it; I now see though at least in this case, it is Mr. Williams who has ignored the scientific data.

If I were to ask Mr. Williams’ statistician the odds of having two compromised dating techniques (U/U and U/Th) suggest the same compromising factor (i.e., loss of Lead), while simultaneously agreeing on the general range of the majority of the dates (i.e., 3.5 to 4.2 billion years), I would expect to hear that the odds are pretty small.  This inclines to me believe the researchers’ interpretation of the data, and their explanation for the anomalous findings.

Now, I will admit that Mr. Williams’ article did in fact make it seem like he might know more about the subject than the researchers, that the researchers were ignoring evidence that was right in from them.  However, they did not ignore it.  They analyzed it extensively.  It is clear from Mr. Williams’ characterizations of the research that he read the paper and understood it, but then dismissed it.  Had he dismissed it in a manner explaining why Uranium doesn’t decompose into Lead, or why zircons do not lose lead, or found a faulty assumption that found its way into all of the subsequent results, I would have considered it.  However, no such evidence is offered, and no citations for such evidence is offered.  The researchers however acknowledged the difficulties of their findings, and then explained how they could make sense, using evidence independently derived from other studies.

Will all of this convince Mr. Williams, or other YECs of his ilk? I do not expect it would.  After all, he read the same study I did.  Of course, his article is 12 years old, and so may not represent what he believes today.  However, it is the same type of approach (although better informed) as what I see over and over from YECs who criticize dating techniques.  Here is how he closes his article:

When I presented this and similar criticisms of isotope dating to a gathering of the Lucas Heights Scientific Society (Sydney, Australia) in 1989, the only response that came from the chief of the division responsible for isotope dating at the Australian Nuclear Science and Technology Organization was the question, ‘Do you have a better dating method?’

I said ’No’, and he appeared to be satisfied that if there are no better methods of dating, then these are good enough.  But can you ride a bicycle into the past simply because no one else has a better time-machine?  Of course not.  In the same way it is absurd to argue that an inadequate method is adequate because nothing better is available.

I agree that a scientist would never argue that, and I have yet to hear it from one.  However, I see it from YECs all the time.  Their bicycle is their interpretation of Genesis 1 (with all due respect to Mr. Williams):

When I present criticisms of a young earth interpretation of Genesis 1, the only response I get is why I do not believe the scriptures.  When I say, “I do believe the scriptures” the YEC typically appears satisfied that there are no better interpretations of Genesis 1 than that of a young earth.  But, can you ride a bicycle into the past simply because no one else has a better time-machine?  Of course not.  In the same way it is absurd to argue that an inadequate interpretation of Genesis 1 is adequate because nothing better is available.  But then, I do think a better interpretation is available: Geocreationism.

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NOTE: If you want to read the actual 1986 study, you can buy it here: http://www.nature.com/nature/journal/v409/n6817/pdf/409144a0.pdf

The 2001 article can be purchased here: http://www.nature.com/nature/journal/v409/n6817/pdf/409144a0.pdf 

This entry was posted on Friday, September 21st, 2007 at 10:01 pm and is filed under Day 1, The Science, Creationism, Evolution. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.