Its important to be reminded that, though many things many be measured on a rock whose origin has not been observed (size, weight, mass, composition, density, etc), age is not one of them. Therefore, to call radiometric dating an absolute dating method (which many textbooks do) is misleading. As we shall see, all radiometric dating consists of, in reality, is a study of the elemental composition of a particular specimen. Age is determined when certain assumptions are applied to these compositional findings. Note that these assumptions, all of them, are unproven and unprovable.
Authur N. Strahler, a committed anti-creationist, explains the concept behind radiometric dating (“Principles of Earth Science”, 1976, p. 23, 68):
“A key to the understanding of radioactivity is that isotopes are unstable. This instability can result in the flying off of a small part of the nucleus. The original element is thus transformed into a different element, having a different name. In this spontaneous breakdown, mass is converted into energy, released into the surrounding matter and finally transformed into sensible heat. The term radioactive decay covers the entire process…At the time of solidification of an igneous rock from its liquid state, minute amounts of minerals containing radioactive isotopes are trapped within the crystal lattices of the common rock-forming minerals, in some cases, forming distinctive radioactive minerals. At this initial point in time there are present none of the stable daughter products of that constitute that end of the decay series. However, as time passes the stable end member of each series is produced at a constant rate and accumulates in place.
Each radioactive isotope has its own rate of decay, which is absolutely constant….Knowing the half-life if the decay system, we can estimate closely the time elapsed since mineral crystallization occurred. An accurate chemical determination of the ratio between the radioactive isotope and the stable daughter product must be made. A fairly simple mathematical equation is used to derive the age in years of the mineral under analysis.”
At first blush, the methodology being applied seems scientifically sound. Under closer inspection, the problems with this form of “absolute” dating become apparent.
To begin with, its important to acknowledge that no one really understands just why isotopes decay in the first place.
From William D. Stansfield, Science of Evolution”, 1977, p. 82:
“For some inexplicable reason, the nuclei of certain elements becomes unstable and spontaneously release energy and/ or particles.”
Not knowing for certain why this process happens ought to make a thinking person leery about using radiometric dating a reliable method for peering into the distant past. For certain, one ought to think twice before hanging their eternity on a method based on a physical process whose fundamental nature is not fully understood.
David Harry Grinspoon has taken such a bold (I would say foolish) approach. An ardent anti-creationist, Grinspoon has used the radiometric dating method as proof positive that the Bible is errant (see: “Venus Revealed”, 1997). A lot of people share Grinspoon’s opinion that radiometric dating has safely proven the Bible wrong. The following data will hopefully help you make up your own mind.
Types of Radiometric Dating Methods
The Chart below outlines some of the most common forms of “absolute dating” and the basic premise behind each:
|Potassium-Argon (K-Ar) Dating||“40K, the radioactive form of potassium decays at an established rate and forms argon (40Ar). Since the half life (the amount of time it takes for half a given quantity of an isotope to decay) of 40K is a known quantity, the age of a material containing potassium can be measured by the amount of 40K compared to the amount of 40Ar it contains.”||“Anthropology” Seventh Ed., Carol R. Ember, Melvin Ember, 1993, p. 51|
|Uranium-Lead Dating||This technique is essentially the same as the K-Ar dating method, only here the “parent” isotope is Uranium and the “daughter” is lead.||Arthur N. Strahler, “Principles of Earth Science”, 1976, pp. 68-69|
|Rubidium-Strontium Dating||Essentially the same as U-Pb and K-Ar dating techniques, where Rubidium is the “parent” and Strontium is the “daughter”.||John D. Morris, “The Young Earth”, 2000, p.57|
|Fission Track Dating||“It entails counting the number of paths, or tracks, etched in the sample by the fission (explosive division) of uranium atoms as they disintegrate. Scientists know that U-238 decays at a slow steady rate. This decay takes the form of spontaneous fission, and each separate fission leaves a scar or track on the sample, which can be seen when chemically treated through a microscope. To find out how old a sample is, one counts the tracks then measures their ratio to the uranium content in the sample.”||“Anthropology” Seventh Ed., Carol R. Ember, Melvin Ember, 1993, pp. 51-51|
|Thermoluminescence Dating||“…makes use of the principle that if an object is heated at some point to a high temperature (as when clay is baked to form a pot), it will release all the trapped electrons it held previously. Over time, the object will continue to trap electrons from radioactive elements around it. The amount of thermoluminescence that is emitted when the object is heated during testing allows researchers to calculate the age of the object, if it is known what kind of radiation the object has been exposed to in its surroundings.”||Ibid., p. 91|
|Electron Spin Resonance Dating||“…is a technique that, like thermoluminescence dating, measures the trapped electrons from the surrounding radioactive material. But the method in this case is different. The material to be dated is exposed to varying magnetic fields and a spectrum of the microwaves absorbed by the tested material is obtained. Since no heating is required for this technique, electron spin resonance dating is especially useful for dating organic material such as bone and shell…”||Ibid., p. 91|