Assumptions of Radiometric Dating

Author: Doug Sharp
Subject: Geology
Date: updated 3/17/2003

I will attempt to give you a few answers to your questions concerning radiometric dating. If you want to study what creationists say about radiometric dating in depth, I recommend three books, The Mythology of Modern Dating Methods and Studies in Flood Geology, both by John Woodmorappe and Creation’s Tiny Mystery by Robert Gentry. John Woodmorappe’s books are advertised elsewhere on my web site. These books contain an exhaustive study of radiometric dates that do not fit the results evolutionists expect. There is also an exhaustive study of this subject called the RATE(Radioisotopes and the Age of the Earth) Group, a team of six scientists who are investigating the subject in depth, and have published the first of several studies.

There are several methods of radiometric dating. Carbon-14 dating has limited value for evolution because its half-life is too short. The method assumes that the production of Carbon-14 in the atmosphere from nitrogen is a process that is in equilibrium, and it is not.

The other methods deal with dating igneous rocks. Sedimentary rocks normally cannot be dated with radiometric methods (there are a few exceptions) because they do not have crystals that were consolidated at the time the rock was formed. Therefore, since sedimentary rock is the only kind of rock that bears fossils, a relative date is estimated by the position of a sedimentary rock in relation to an igneous outflow. There is a discussion of a few examples of radiometric methods with sedimentary rocks in Mythology of Modern Dating Methods.

Creationists believe that the assumptions of radiometric dating are invalid and cannot be proven. These assumptions are:
(1) the radioactive element decays at a constant rate
(2) the rock crystal being analyzed is not contaminated by infusion of excess end product
(3) the rock crystal contained no end product when it was formed
(4) leaching of the parent element out of the rock sample did not occur.

The Potassium-Argon dating method suffers from both leaching and contamination problems. Rubidium-Strontium and Uranium-Lead also has problems of the same kind. Potassium, Rubidium and Uranium salts are highly soluble. Leaching of the parent element out of the rock would increase the age of a K-Ar sample. One way to test this would be to analyze the sample before and after soaking it under pouring water. This would reduce the concentration of the potassium ions to the point that it would increase the date of the rock dramatically. I have heard that this experiment has been done, demonstrating this effect (I am searching for the reference).

Studies of Mt. St. Helens rock known to have come from the 1980 eruption (Creation Ex Nihilo Technical Journal) yielded erroneous dates in the millions of years. Similar studies at the Grand Canyon found volcanic rocks dated at the top of the canyon older than those found in the bottom. Something’s wrong here.

One of the tests that has not been done on the method is to subject it to a double blind study. That is where the sample of interest is tested along with several others of the same rock type, but from different areas. Check out Dr. Walt Brown’s book on-line at The Center for Scientific Creation.  On page 64 of his book he describes the double blind test needed to establish credibility for radiometric dating. We believe that since evolutionists expect certain rocks to yield dates that agree with their theory, no laboratory will publish dates that are wildly out of whack, or they wouldn’t get paid for producing a result that would be hotly contested as experimental error. Woodmorappe shows that even the published results are enough to render the method as unreliable.

In any event, radiometric dating doesn’t disprove the Bible. It never will unless somehow you could go back in time and observe the process from the formation of the rocks to the present and verify the assumptions to be true.