Using Radiocarbon Dating to Establish the Age of Iron-Based Artifacts
Archaeologists routinely use radiometric dating to determine the age of materials such as ancient campfires and mammoth teeth. Radiocarbon dating has been used to determine of the ages of ancient atmosphere is threatening to skew the accuracy of this technique for. We can also confirm that dating methods that use other radioactive accurately model the chemical composition of stars multiple billions of.
Recent advances include simplification in sample preparation and reduction in sample size for accelerator mass spectrometry measurements, and the potential use of rust as a viable source of material for radiocarbon dating.
Additionally, a summary is presented of all 63 previously published results for iron-based materials and 29 new results that have not been published previously. These materials range from low-carbon wrought irons to medium to very high-carbon steels and cast irons. Artifact dates range from several hundred years ago to several thousand years ago.
Brief descriptions are given of some of these examined samples to illustrate issues and complexities that can arise in determining the age of iron-based carbon materials using radiocarbon dating. A recent summary has been published 1 of techniques for dating that range from astronomical methods to cover time scales from the age of the universe e.
One well-known method for dating is based on the use of isotopic techniques. Included are reactions such as the uranium-to-lead transformation utilized for dates that range from 1 billion years to 4.
Perhaps the best-known isotopic technique, however, is that of radiocarbon [e. The present paper deals with an issue of great interest to materials scientists and archeologists—the dating of iron-based materials that contain carbon.
How reliable is geologic dating?
In addition, however, the corrosion products or rust from these materials is included since they can also be used for dating in some cases. For the case of iron-based materials, the time span of interest is from the start of the Iron Age in the regions of interest about B. The most appropriate method for this time span and group of materials is 14C dating. It is key to point out that the usefulness of the method of dating carbon in iron-based materials relies on the source of the carbon found in the materials see sidebar.
For the case of iron-based materials, van der Merwe and Stuiver 2 first demonstrated that it was feasible to extract the carbon from different iron-based materials and use it to establish their age using radiocarbon dating. A total of 15 samples of iron-based materials were dated by beta counting at Yale University 23 using a dependable method to extract carbon from iron utilizing flow-through combustion in oxygen with cryogenic trapping of CO2.
These studies showed that in a wide range of cases, the carbon in iron-based materials could be extracted and reliably radiocarbon dated. The Yale beta counter, however, required significant amounts of carbon compared to the amounts that were usually available from artifacts without consuming or damaging them. The amount of carbon required was 1g, equivalent to 50 g of a 2.How Carbon Dating Works
In the late s, radiocarbon dating by accelerator mass spectrometry AMS became common. This new methodology required only 1 mg instead of 1 g of carbon. Inthe present authors published 9 a new carbon-extraction method for iron based on a sealed-tube combustion with CuO in quartz.
This greatly simplified the previous technique and required only materials readily available in the standard AMS graphite-preparation laboratory: Unlike the previous techniques, no exotic gas-trapping equipment is required.
Thus, over the years, the sample-size requirement has been greatly reduced and the carbon-extraction procedure has been simplified. However, as has been mentioned, for a radiocarbon date on iron to be meaningful, the carbon extracted from the iron-based material must be from biomass contemporaneous with original manufacture. In addition to fossil fuels such as coal and coke, other carbon sources such as geological carbonates e.
Complications arising from the recycling of artifacts must also be considered. These limitations of the dating technique have been well summarized by van der Merwe 3 and Cresswell. If rust can be dated reliably, it opens up a large number of possibilities for dating iron artifacts.
Investigators will not need to cut into valuable artifacts for clean metal, but will be able to use surface corrosion products. This potentially opens the way for dating precious samples such as the iron plate found in the Great Pyramid at Gizeh, 1011 now at the British Museum.
It may also be possible to date completely rusted artifacts, commonly found in waterlogged early Iron-Age sites in Europe and in underwater shipwrecks. Previous investigators had been careful to remove rust from iron prior to dating for fear that it adds contamination. A key issue though, is whether any of the original carbon remains within the matrix of rust and other corrosion products. These isotopes have longer half-lives and so are found in greater abundance in older fossils.
Some of these other isotopes include: The assumptions are similar to the assumptions used in carbon dating. The mathematical premise undergirding the use of these elements in radiometric dating contains the similar confounding factors that we find in carbon dating method.
Most scientists today believe that life has existed on the earth for billions of years. This belief in long ages for the earth and the evolution of all life is based entirely on the hypothetical and non-empirical Theory of Evolution.
All dating methods that support this theory are embraced, while any evidence to the contrary, e. Prior to radiometric dating, evolution scientists used index fossils a. A paleontologist would take the discovered fossil to a geologist who would ask the paleontologist what other fossils searching for an index fossil were found near their discovery.
Carbon, Radiometric Dating - CSI
If it sounds like circular reasoning, it is because this process in reality is based upon circular reasoning. Henry Morris as follows: These long time periods are computed by measuring the ratio of daughter to parent substance in a rock, and inferring an age based on this ratio.
This age is computed under the assumption that the parent substance say, uranium gradually decays to the daughter substance say, leadso the higher the ratio of lead to uranium, the older the rock must be. While there are many problems with such dating methods, such as parent or daughter substances entering or leaving the rock, e. Geologists assert that generally speaking, older dates are found deeper down in the geologic column, which they take as evidence that radiometric dating is giving true ages, since it is apparent that rocks that are deeper must be older.
Everything Worth Knowing About ... Scientific Dating Methods
But even if it is true that older radiometric dates are found lower down in the geologic column which is open to questionthis can potentially be explained by processes occurring in magma chambers which cause the lava erupting earlier to appear older than the lava erupting later. Lava erupting earlier would come from the top of the magma chamber, and lava erupting later would come from lower down.
A number of processes could cause the parent substance to be depleted at the top of the magma chamber, or the daughter product to be enriched, both of which would cause the lava erupting earlier to appear very old according to radiometric dating, and lava erupting later to appear younger. Other possible confounding variables are the mechanisms that can alter daughter-to-parent ratios. We can see that many varieties of minerals are produced from the same magma by the different processes of crystallization, and these different minerals may have very different compositions.
It is possible that the ratio of daughter to parent substances for radiometric dating could differ in the different minerals. Clearly, it is important to have a good understanding of these processes in order to evaluate the reliability of radiometric dating. Other confounding factors such as contamination and fractionation issues are frankly acknowledged by the geologic community, but are not taken into consideration when the accuracy and validity of these dating methods are examined.
The following quotation from Elaine G. Kennedy addresses this problem. Contamination and fractionation issues are frankly acknowledged by the geologic community.
For example, if a magma chamber does not have homogeneously mixed isotopes, lighter daughter products could accumulate in the upper portion of the chamber. If this occurs, initial volcanic eruptions would have a preponderance of daughter products relative to the parent isotopes. Such a distribution would give the appearance of age.
As the magma chamber is depleted in daughter products, subsequent lava flows and ash beds would have younger dates. It does suggest at least one aspect of the problem that could be researched more thoroughly. The problems inherent in radiometric dating often cause them to be so unreliable that they contradict one another rather than validating each other. It would really be nice if geologists would just do a double blind study sometime to find out what the distributions of the ages are.
In practice, geologists carefully select what rocks they will date, and have many explanations for discordant dates, so it's not clear how such a study could be done, but it might be a good project for creationists. There is also evidence that many anomalies are never reported. There are so many complicated phenomena to consider like this that it calls the whole radiometric dating scheme into question. Only then can you gauge the accuracy and validity of that race. We need to observe when the race begins, how the race is run are there variations from the course, is the runner staying within the course, are they taking performance enhancing drugs, etc.
All bases must be covered if we are going to accurately time the race.