Radioactive carbon dating and radiometric dating, radiometric dating
We will also get a distribution of averaged values for samples in each period.
I mentioned the presence of excess argon 40 in a sample as a problem leading to artificially old K-Ar dates. For each geologic period and each dating method, we will get a distribution of values. Closed System It is assumed that we are dealing with a closed system—no loss of either parent or daughter elements has occurred since the study material formed.
This could account for the observed distribution of potassium-argon dates, even if the great sedimantary layers were laid down very recently.
And how do we know that it could not be a much larger quantity in other cases? And since this agreement is the strongest argument for the reliability of radiometric dating, such an assumption of agreement appears to be without support so far. Visual Layers Summer ice has more bubbles and larger crystal sizes Observed to 60, years ago Dust Layers Measured by laser light scattering; most dust is deposited during spring and summer Observed toyears ago Layering of Elec-trical Conductivity Nitric Chase johnson dating from the stratosphere is deposited in the springtime, and causes a yearly layer in electrical conductivity measurement Observed through 60, years ago Contaminant Chemistry Layers Soot from summer forest fires, chemistry of dust, occasional volcanic ash Observed through 2, years; some older eruptions noted Hydrogen and Oxygen Isotope Layering Indicates temperature of precipitation.
These two independent and agreeing dating methods for of the age of two primary members of the solar system formed a strong case for the correctness of his answer within the scientific Radioactive carbon dating and radiometric dating.
We must conclude that all evidence points towards unchanging radioactive half-lives.
This indicates that some excess argon is present. Some Christians have argued that something may be slowly changing with time so all the ages look older than they really are. If they contained a hundred times more excess argon, their K-Ar ages would be a hundred times greater, I suppose.
Other flows with wide biostratigraphic limits have weak restrictions on allowable dates. A stronger magnetic field shields the upper atmosphere better from charged cosmic rays, resulting in less carbon production now than in the past.
Now, argon is very soluble in magma, which can hold a lot of it: Thus we can get an apparent correlation of different methods without much of a real correlation in nature.
Once 14C is produced, it combines with oxygen in the atmosphere 12C behaves like 14C and also combines with oxygen to form carbon dioxide CO2. The bottom two entries, uranium and thorium, are replenished as the long-lived uranium atoms decay.
Generally, excess 40Ar is observed in minerals that have been exposed to a high partial pressure of argon during regional metamorphism, in pegmatites However, since it is possible for argon to be formed in the rocks by cosmic radiation, the correction may also be in error.
However, this causes a problem for those who believe based on the Bible that life has only existed on the earth for a few thousand years, since fossils are found in rocks that are dated to be over million years old by radiometric methods, and some fossils are found in rocks that are dated to be billions of years old.
As it ages, some of its uranium decays to thorium It would be difficult to measure the tiny changes in concentration that would suffice to make large changes in the radiometric ages over long time periods. Intrusive bodies are deposited in the spaces between other rocks.
I looked up some information on bentonite.
I'm not claiming that anomalous results are being hidden, just that the agreement of a mass of results, none of which has much claim to reliability, does not necessarily mean much.
Since most cave formations have formed relatively recently, formations such as stalactites and stalagmites have been quite useful in cross-calibrating the carbon record. Modern lava flows often come down the sides of volcanoes, and thus become separated from their source by large distances.
Thus any method based on simple parent to daughter ratios such as Rb-Sr dating is bound to be unreliable, since there would have to be a lot of the daughter product in the magma already. Rubidium parent atoms can be leached out of the rock by water or volatilized by heat.
How radiometric dating works in general Radioactive elements decay gradually into other elements.