Independent radiometric methods verify each other
Evolutionists claim the various methods of radiometric dating do not have the same sort of problems, so when different methods result in giving the same age for a rock, that must be the rock’s true age. For example, a rock might be dated by the uranium/lead method, and then by the potassium/argon method. Argon is a gas. Because it is a gas, when magma erupts out of the earth, argon escapes because the lava is still molten. The clock is reset. One can be certain that the initial concentration of argon is zero. Therefore, the equations for solving time since formation of the rock will be accurate because no assumption has to be made about the amount of argon present when the rock first formed. If the age from potassium/argon dating and the date derived from uranium/lead dating agree, then the date must be correct. This is a case where two independent methods verify one another. We could consider situations in which other methods could be done that also would agree, but let’s consider just these two.
Fractional crystallization might cause the magma to have an artificially old date, but could this happen with the potassium/argon method? First, there is no guarantee that all the argon initially in the rock escapes while it is still molten. There are many known instances of lava flows occurring in the last few hundred years. Yet, when the flows are dated, the ages are excessive, dating several million years old.
One oil geologist, a creationist, questioned Woodmorappe's remarks, saying that radiometric dating is reliable because there are more "too young" results than "too old" results. Woodmorappe replied:
Actually, the fact that there are more "too young" values means very little, for something being "too young" or "too old" presupposes that there already is a "correct" value with which to compare all other results! That there are more "too young" than "too old" values probably only means that geochronologists have come to believe that older results tend to be accurate and hence have come to accept older results (selected from the welter of contradictory results) as being "correct." [Woodmorappe, 1985]
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Gunter Faure explains that the U.S. Geological Survey used to have much younger uranium/lead ages accepted as correct. [Faure, p.282] When older dates were obtained by a different way of measuring the ratio of lead and uranium, geologists decided the older dates were correct. They had to explain away Holmes’ time scale as coming from argon-purged and strontium-purged samples, which made them too young. After all, if the argon in a sample were somehow removed, at least in part, the sample's age would appear younger since argon is the decay product of potassium (see below). This is one reason why Woodmorappe says, there is now a superabundance of too young results.
The Grand Canyon The Grand Canyon, long touted by evolutionists as clear evidence for long geological ages, holds many surprises and contradictions for evolutionists and their theory. Vastly different dates have been derived for the top and bottom layers of Grand Canyon. Rocks dated by the isochron method by five independent laboratories consistently showed that samples taken from lava flows at the top of Grand Canyon by Institute for Creation research geologists were about one billion years older than samples taken from the basement rocks in the canyon. The Moon Rock samples brought back from the moon were tested and dated. Some were only millions of years old, while others were 28 billion years old. The moon is assumed to be 4-4.5 billion years old by evolutionists. The following table shows the wide age spread scientists measured in moon rocks brought back during the Apollo program. [Whitcomb] |
| Apollo Sample |
Ages in Billions of Years |
Age Inconsistencies, | ||
| No. |
Uranium-Thorium-Lead Method |
Potassium- | extremes in billions | |
|
Low |
High |
Argon Method | of years | |
| 10017 | 3.60 | 4.79 | 2.2 | 2.59 |
| 10057 | 3.96 | 4.17 | 2.3 | 1.87 |
| 10060 | 3.36 | 5.76 | -- | 2.40 |
| 10084 | 4.31 | 8.20 | >7 | 3.89 |
| 12070 | 3.63 | 4.50 | >7 | >3.37 |
| 12032 | 3.38 | 4.40 | >7 | >3.62 |
| 12063 | 3.75 | 4.09 | 2.6 | 1.49 |
| 12013 | .7* | 4.6 | >6 | >5.3 |
| 14310 | 5.3 | 11.2 | -- | 5.9 |
| 14053 | 5.4 | 28.1 | -- | 22.7 |
| 15426 | 4.6 | 16.2 | -- | 11.6 |
| 66095 | 5.6 | 14.1 | -- | 8.5 |
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*Age determination using a Uranium-Thorium/Helium Technique |
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These are the results the investigators were willing to publish. It is often the case that discordant dates are withheld, ignored, or thrown out. Then when the accepted dates are presented, the comment is "See how close these results are in agreement with previous determinations!" Of course, they are going to be in agreement. How could they be anything else when discrepant dates are thrown out? Brent Dalrymple (USGS) excluded the discrepant moon rock dates from his book Age of the Earth. He affirmed that all the dates obtained from moon rocks agreed with one another within a few million years at most.
The Koongarra Uranium Deposit
Andrew Snelling, a geologist committed to creationism, questions the validity of radiometric dating procedures designed to produce isochrons. [Snelling, 1994] Isochron dating is supposed to be the most reliable means for getting the correct age of a rock and for assuring that the age is correct. The isochron methods have a built-in checking system
Sources of Error In The Laboratory
When scientists are dating a rock sample, Faure points out that there are several sources of laboratory error, which can greatly affect the results obtained. Let’s assume that the laboratories doing the dating have reliably overcome the obstacles and concentrate on more difficult problems in dating a rock.
If the ages of rocks measured in a laboratory do not agree with the assumed ages of the strata in which they were found (based on the index fossils), the dates are considered wrong and are usually discarded. If geologists find a rock in a Cambrian formation, its measured age must be near the 500-570 million year range, plus or minus 50 million years to be acceptable (some labs are more generous).
Faure says the most likely uncorrected laboratory error is unconfirmed lab results because the methods are time consuming, "which discourages replication of analyses and thereby results in inadequate documentation of analytical errors." [Faure, pp. 62-63]
If this is true, not many geologists spend the extra time and money to verify their results. What geologists often do if a date falls too far outside the predetermined age range, is either to discard the result or to declare the date discordant. There are established methods for deciding whether a result is discordant. Faure provides some basic guidelines for establishing "concordia" and "discordia," e.g., Uranium-Lead systems. [Faure, pp. 291-304].
Efforts are made to minimize laboratory errors, but they do crop up, and they probably crop up with greater frequency that the laboratories would like to admit. In summarizing his chapter on Uranium, Thorium-Lead methods of dating, he says that in many cases the resulting dates are discordant due to loss of Lead or Uranium.