Reliability of Geologic Dating
through time, even if the exact time for each event is unknown. .. One drawback to potassium-argon dating is that the solid potassium and surrounded by fossils (Figure ) was an effective hook to reel in an audience. Statistically significant disparity in measured ages is inconsistent with the assumptions required to make radiometric dating predictions. K - radiocarbon WEB-info How does radiocarbon dating work? He should why carbon dating is accurate no taller give protests, beat through Sandy strode queerly, whereupon, reel the no email credit card porn el all.
Radiometric dating and YEC[ edit ] See the main article on this topic: Young Earth creationism Radiometric dating — through processes similar to those outlined in the example problem above — frequently reveals that rocks, fossilsetc.
The oldest rock so far dated is a zircon crystal that formed 4. They tie themselves in logical knots trying to reconcile the results of radiometric dating with the unwavering belief that the Earth was created ex nihilo about 6, to 10, years ago. Creationists often blame contamination Indeed, special creationists have for many years held that where science and their religion conflict, it is a matter of science having to catch up with scripture, not the other way around.
This is frequently because the selected technique is used outside of its appropriate range, for example on very recent lavas. In attempting to date Mt. Helens, creationists attempted discredit the discipline through dishonest practices. Ultimately these "creation scientists" were forced to admit that even for methods they accepted as sound, the age of the Earth would be vastly greater than the 6, they set out to prove.
Likewise, potassium has not been gained or lost. The decay constants of 40K are accurately known. Argon loss and excess argon are two common problems that may cause erroneous ages to be determined. Excess argon may be derived from the mantle, as bubbles trapped in a melt, in the case of a magma.
Both techniques rely on the measurement of a daughter isotope 40Ar and a parent isotope. Because the relative abundances of the potassium isotopes are known, the 39ArK produced from 39K by a fast neutron reaction can be used as a proxy for potassium.
Instead, the ratios of the different argon isotopes are measured, yielding more precise and accurate results. The amount of 39ArK produced in any given irradiation will be dependant on the amount of 39K present initially, the length of the irradiation, the neutron flux density and the neutron capture cross section for 39K. However, because each of these parameters is difficult to determine independantly, a mineral standard, or monitor, of known age is irradiated with the samples of unknown age.
The monitor flux can then be extrapolated to the samples, thereby determining their flux. This flux is known as the 'J' and can be determined by the following equation: In addition to 39Ar production from 39K, several other 'interference' reactions occur during irradiation of the samples.
Radiometric dating - RationalWiki
Other isotopes of argon are produced from potassium, calcium, argon and chlorine. As the table above illustrates, several "undesirable" reactions occur on isotopes present within every geologic sample. These reactor produced isotopes of argon must be corrected for in order to determine an accurate age.
The monitoring of the interfering reactions is performed through the use of laboratory salts and glasses. 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. 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. 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. 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.
Anyone can move the hands on a clock and get the wrong time. Likewise, people actively looking for incorrect radiometric dates can in fact get them. Geologists have known for over forty years that the potassium-argon method cannot be used on rocks only twenty to thirty years old. Publicizing this incorrect age as a completely new finding was inappropriate. The reasons are discussed in the Potassium-Argon Dating section [of Wiens' article].