|Feature Article - February 1997|
|by Do-While Jones|
You may hear it said that certain rocks are so many million (or billion) years old. Most people assume that scientists really know how old the rocks are. The truth is, they don't. The more you study about the various methods for determining the age of the rocks, the more you will realize how unreliable those methods are. The accuracy of these dates is important because they are used to establish the theory of evolution. If these dates are wrong, then the theory of evolution is wrong.
The radioactive dating controversy of a fossil known as Skull KNM-ER 1470 is well-documented. 1 Skull 1470 was discovered by Richard Leakey in 1967. This skull, very modern in appearance, was found in a layer of rock that was believed to be too old to contain a modern skull. Since evolutionists considered this to be important evidence that would tell them when apes evolved into men, they wanted to know exactly how old the skull was. Fortunately, the skull was found beneath a layer of volcanic ash which they believed could be accurately dated. Since Skull 1470 was found in rocks under this layer of ash, the skull must be slightly older than this layer of ash.
Samples of the layer of ash were sent off to the laboratory. Richard Leakey hoped the lab would confirm his estimate of 2.9 million years. (That would make him the discoverer of the oldest human fossil.) But the laboratory results gave dates ranging from 212 to 230 million years old. This was far too old to fit the theory of evolution, so the lab results were rejected.
Over the next ten years the rocks surrounding Skull 1470 were dated dozens of times, using various methods, giving widely varying results. For example, two specimens from the same layer were analyzed by the same people (Fitch and Miller) using the same technique during the same analysis. One specimen was dated at 0.52 to 2.64 million years old. The other was dated at 8.43 to 17.5 million years old.
It is tempting to include a chart of all the different ages given for the rocks surrounding Skull 1470, but the numbers really don't mean much unless you know who did the measurements and what age they were trying to get. The Lubenow reference 1 gives all the numbers and puts them in perspective.
Of all the radioactive dating techniques, only the carbon 14 (abbreviated 14C) method gives generally accurate results for recent dates. We know this because 14C dates compare well with historical data. But 14C dating isn't of much interest to evolutionists because it only works for things that were once alive, and therefore doesn't work for rocks. Even if it did work for rocks, the evolutionists wouldn't care because the half-life of 14C is so short that it is all gone in several thousand years. It would not work on anything a million years old.
The radioisotope methods used for rocks, potassium-argon (K-Ar), rubidium-strontium (Rb-Sr), and lead-lead (Pb-Pb) don't give reliable results. That's because they actually measure the present ratio of elements in the rocks, which is more greatly influenced by the initial ratio of the elements in the rocks than it is by the age of the rocks.
Potassium decays to argon at a known rate. Therefore, if you know the initial amount of potassium and argon when the rock was formed, then you can measure the amount of potassium and argon that is still in the rock to see how much potassium has decayed to argon. Knowing this you can compute the age of the rock. (The same reasoning holds for the Rb-Sr and Pb-Pb methods.) A typical geology textbook will tell you,
The K-Ar method of dating differs from the other common methods by involving a decay product [argon] that is an inert gas. Even at moderately low temperatures (see discussion below), this gas is a fugitive component and is typically not incorporated in minerals. Thus a newly formed mineral contains no argon to begin with, but with time, 40K decays slowly to 40Ar; this argon remains in place as long as the system is not disturbed. The method, in principle, then is not affected by initial isotopic ratios, as is the Rb-Sr method. ( ) For an age determination by the K-Ar method to be accurate, the assumption that no radiogenic argon was present to begin with must be valid.2 [emphasis supplied]
So, the assumption is that when lava comes out of a volcano, all the argon gas escapes from the lava before the lava cools enough to harden. Therefore, all the argon trapped in the lava comes from decayed potassium. That is a plausible assumption, but is it correct?
One way to test this assumption is to measure the K-Ar age of several recent lava flows.3 The Sunset Crater lava flows (from an eruption around 1065 A.D.) have been dated at 210,000 to 230,000 years old. 4 Lava from the Mt. Rangitoto eruption which happened 300 years ago has been dated at 485,000 years old. 5 The Kaupelehu Flow (1800 - 1801 A.D.) has been dated several times, yielding 12 dates ranging from 140 million years to 2.96 billion years, with an average date of 1.41 billion years. 6
These references are nearly 30 years old, so you might think that radioactive dating has improved in recent years. It hasn't. Lava from a 1986 Mount St. Helens lava dome has just been dated at 2.8 +/- 0.6 million years old. 7
The previously quoted textbook said, "The [potassium-argon] method, in principle, then is not affected by initial isotopic ratios, as is the Rb-Sr method." In other words, for radioactive dating methods to work, you must know the initial ratio of the isotopes. The popularity of the potassium-argon method is due to the belief that you can assume the initial ratio of argon to potassium is zero. Laboratory tests, as we have just seen, have repeatedly shown that the initial ratio isn't zero. The assumption that young rocks are free of argon is wrong.
But the difficulties are even worse for Rb-Sr, Pb-Pb, and other radioactive methods because you don't even have the slightest justification for assuming any initial ratio. The evolutionist simply guesses an initial value that is likely to yield a date in the desired ball park. If the resulting date supports the evolutionist's theory, the date becomes gospel. If the date doesn't, then it is rejected as "discordant." It is scandalous that results are accepted or rejected simply on the basis of whether a scientist likes the answer or not.
Radioactive elements with short half-lives, like 14C, can only be used to determine young ages. Carbon 14 doesn't last long enough to measure old ages. More stable elements, like 206lead, which have very long half-lives, are used in age calculations that yield values in billions of years. They can't be used for short intervals because not enough of the element decays in a short time to be measured. This means that the range of possible outputs from the calculations will depend upon the half-life of the element you choose. Therefore, the choice of the dating method determines how old the rock will appear to be. One geology teacher said it this way,
After all field relationships have been established (i.e. stratigraphy, cross-cutting relationships, relative dating, etc.), samples from strata in question are thoroughly examined for their geochronological appropriateness. After sample(s) are deemed worthy of further analysis, then only the appropriate dating technique with an appropriate effective dating range is used. 8 [emphasis his]
This is not a valid approach for a scientist to take. It does not give an independent confirmation of the age of the rock. Selecting a dating method based on the presumed age of the rock merely puts a numerical value on a subjective prejudice.
Radioactive methods cannot determine the age of rocks because there is a fundamental flaw in the method. Yes, we know how rapidly radioactive elements decay. Yes, we can measure the amount of the isotopes in the rock now. But without knowing how much of each isotope was there to begin with, it isn't possible to tell how long the decay has been going on because we don't know how much of the daughter product is the result of decay.
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1 Lubenow, Marvin L.,
Bones of Contention Appendix: The Dating Game
2 Philpotts, Anthony R., Principles of Igneous and Metamorphic Petrology, page 430 (Ev)
3 Morris, John, The Young Earth, pages 54-55 (Cr+)
4 Dalrymple, G. B., "40Ar/36Ar Analyses of Historical Lava Flows," Earth and Planetary Letters, Vol. 6, 1969, pages 47-55 (Ev)
5 McDougall, I., et al., "Excess Radiogenic Argon in Young Subaerial Basalts from Auckland Volcanic Field, New Zealand," Geochemica et Cosmochemica Acta, Vol. 33, 1969, pages 1485-1520 (Ev)
6 Funkhouser, John G., and Naughton, John J., "Radiogenic Helium and Argon in Ultramafic Inclusions from Hawaii," Journal of Geophysical Research, Vol. 73, No. 14, July 1968, pages 4601-4607 (Ev)
7 Austin, S. A., "Excess Argon within Mineral Concentrates from the New Dacite Lava Dome at Mount St Helens Volcano", Creation Ex Nihilo Technical Journal, Vol. 10, No. 3, 1996, page 355 (Cr+)
8 Sabin, A. "Geochronology Overview, Ch. 9", October 30, 1996 (Ev-)