How reliable is geologic dating?
Is radiometric dating a reliable method for estimating the age of something? First, they tend to think that scientists can measure age. . As it turns out, there is compelling evidence that the half-lives of certain slow-decaying. Willard Libby invented the carbon dating technique in the early s. over a century before there were any radio- metric dating methods. Are radiometric dating methods accurate? Does Radiometric Dating Prove the Earth is Old? How accurate are carbon-dating methods?.
This assumption is backed by numerous scientific studies and is relatively sound. However, conditions may have been different in the past and could have influenced the rate of decay or formation of radioactive elements.
Evolutionists assume that the rate of cosmic bombardment of the atmosphere has always remained constant and that the rate of decay has remained constant. Thus radioactive dating relies purely on assumptions. We could put forward the following counter arguments to the constancy of these assumptions: The current high rate of entry might be a consequence of a disturbed post-Flood environment that altered the carbon to carbon ratio.
Pre-Flood dates would thus have to be discarded. Some scientists argue that the magnetic field of the earth has declined over time. Carbon comes from nitrogen and is independent of the carbon reservoir. If even a small percentage of the limestone deposits were still in the form of living marine organisms at the time of the Flood, then the small amount of carbon would have mixed with a much larger carbon reservoir, thus resulting in a drastically reduced ratio.
As another item of evidence, researchers studying a natural nuclear reactor in Africa have concluded that a certain key physical constant "alpha" has not changed measurably in hundreds of millions of years [ Barrowpg. Finally, researchers have just completed a study of the proton-electron mass ratio approximately Thus scientists are on very solid ground in asserting that rates of radioactivity have been constant over geologic time.
The issue of the "uniformitarian" assumption is discussed in significantly greater detail at Uniformitarian. Responses to specific creationist claims Wiens' online article, mentioned above, is an excellent resource for countering claims of creationists on the reliability of geologic dating.
In an appendix to this article, Wiens addresses and responds to a number of specific creationist criticisms. Here is a condensed summary of these items, quoted from Wiens' article [ Wiens ]: Radiometric dating is based on index fossils whose dates were assigned long before radioactivity was discovered.
This is not at all true, though it is implied by some young-earth literature. Radiometric dating is based on the half-lives of the radioactive isotopes.
- Radiometric Dating Does Work!
- 1. Rate of Decay
- Accuracy of Fossils and Dating Methods
These half-lives have been measured over the last years. They are not calibrated by fossils.
No one has measured the decay rates directly; we only know them from inference. Decay rates have been directly measured over the last years. In some cases a batch of the pure parent material is weighed and then set aside for a long time and then the resulting daughter material is weighed.
In many cases it is easier to detect radioactive decays by the energy burst that each decay gives off. For this a batch of the pure parent material is carefully weighed and then put in front of a Geiger counter or gamma-ray detector. These instruments count the number of decays over a long time. If the half-lives are billions of years, it is impossible to determine them from measuring over just a few years or decades. The example given in the section [in Wiens' article] titled, "The Radiometric Clocks" shows that an accurate determination of the half-life is easily achieved by direct counting of decays over a decade or shorter.
Additionally, lavas of historically known ages have been correctly dated even using methods with long half-lives. The decay rates are poorly known, so the dates are inaccurate. Most of the decay rates used for dating rocks are known to within two percent.
Such small uncertainties are no reason to dismiss radiometric dating. Whether a rock is million years or million years old does not make a great deal of difference. To date a rock one must know the original amount of the parent element. But there is no way to measure how much parent element was originally there. It is very easy to calculate the original parent abundance, but that information is not needed to date the rock. All of the dating schemes work from knowing the present abundances of the parent and daughter isotopes.
There is little or no way to tell how much of the decay product, that is, the daughter isotope, was originally in the rock, leading to anomalously old ages.
Radiometric Dating Does Work! | NCSE
A good part of [Wiens' article] is devoted to explaining how one can tell how much of a given element or isotope was originally present. Usually it involves using more than one sample from a given rock. It is done by comparing the ratios of parent and daughter isotopes relative to a stable isotope for samples with different relative amounts of the parent isotope.
From this one can determine how much of the daughter isotope would be present if there had been no parent isotope.
Radiocarbon dating gets a postmodern makeover
This is the same as the initial amount it would not change if there were no parent isotope to decay. Figures 4 and 5 [in Wiens' article], and the accompanying explanation, tell how this is done most of the time. There are only a few different dating methods. There are actually many more methods out there.
Well over forty different radiometric dating methods are in use, and a number of non-radiogenic methods not even mentioned here. A young-Earth research group reported that they sent a rock erupted in from Mount Saint Helens volcano to a dating lab and got back a potassium-argon age of several million years. This shows we should not trust radiometric dating. There are indeed ways to "trick" radiometric dating if a single dating method is improperly used on a sample.
Charlotte Pearson says it's ready for a makeover. Pearson, an assistant professor of dendrochronology at the University of Arizona, studies the past lives of trees to better understand the history of civilizations.
Dendrochronology and radiocarbon dating have intertwined histories, she explains, with roots firmly planted at the UA. Douglass was a polymath. In addition to his work as an astronomer at the UA's Steward Observatory, Douglass was the first to discover that tree rings record time. They are chronographs, recording clocks, by which the succeeding seasons are set down through definite imprints," he wrote in the pages of National Geographic.
Is Carbon-Dating Accurate? | Radiometric dating | Rate of Decay | Clock Reset | Closed System
In its most conventional form, dendrochronology works like this. A contemporary tree—that is, a tree that was either just cut down or still living—can tell you not just how many years it has lived, but which years in which it lived. If a Bigtooth Maple were cut down on Mount Lemmon in and it had rings, you would know the tree started growing in Tree rings just record. They are impartial recorders of change over time. They have no bias, and they have no political agenda; they just stand at locations all over the world," says Charlotte Pearson, an assistant professor of dendrochronology at the UA, studies samples under a microscope.
Mari Cleven But what if the wood is older? What if it's been used to build a home or a ship or a bonfire? The rings could still tell how many years the tree lived, but not necessarily when. This didn't sit well with Douglass. He set out on a series of expeditions across the southwest to bridge the gap between contemporary wood and wood beams from the ruins of civilizations long gone.
He noticed that trees across the same region, in the same climate, develop rings in the same patterns. Douglass, with his knack for pattern-recognition, discovered that he could take younger wood with a known date, and then match its rings alongside the pattern of an older sample. Inwith a beam from Show Low, Arizona, Douglass was able to bridge the gap for the first time ever. Dates were assigned to Southwestern ruins with certainty. Indeed, the "Secret Of The Southwest" was revealed.
An Isotope Called Carbon But alas, pattern-matching in order to date when a tree was cut isn't always possible. Sometimes a wood sample doesn't have enough tree rings or rings with growth patterns that match an already dated sample.