There are other sources of "old carbon" as well, these days - we've been putting "old carbon" into the atmosphere via burning of fossil fuels in the last odd years, so carbon dating will give a misleading result for anything that's been dead less than the odd years. Creationists who use this claim fail to note that the snails lived in an environment that did not have access to atmospheric C14 a pool formed from a limestone sinkhole. The C14 that the snails did have access to was dissolved out of the limestone, itself, and as a result, was "old" C The scientist didn't measure the living snails themselves. He measured their shells.
Shells are formed by the deposition of calcium carbonate crystals to an organic matrix, which is a protein called conchiolin.
This protein makes up only a few percent of the shell, hence the sample needed in the radiocarbon dating process is the inorganic portion. Although inorganic, the carbonate is still datable since its formation involves incorporation of carbon 14 from the biosphere.
The carbonate present in shells is usually in the form of the mineral aragonite although some shells are mixtures of aragonite and calcite while others, like oyster shell, is mostly calcite. Recrystallization, on the other hand, can affect even the inner layers of a shell.
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This phenomenon, accompanied by the conversion of aragonite to calcite, also alters the carbon 14 ratio. Recrystallization usually occurs when the shell exchanges carbon with modern calcite.
There are two source or reservoir effects relevant to the radiocarbon dating of shells-the marine effect and the hard water effect. Age offset evaluation must be done on radiocarbon dating results on shells because of these effects. The marine effect is a consequence of the slow mixing between surface waters and deep waters in the oceans.
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The rapid exchange of carbon between the atmosphere and the biosphere via the carbon dioxide pathway is not exactly the same between the atmosphere and the oceans. Carbon dioxide equilibrium between the atmosphere and surface waters is achieved relatively quickly.
Surface waters, however, exchange carbon dioxide with deeper waters in a rate that is so slow, the carbon 14 content of the incoming carbon dioxide from the surface water and the outgoing carbon dioxide from the deep waters may already be in different stages of radiocarbon decay.
Studies show that the residence time of carbon 14 in the atmosphere ranges between 6 years and 10 years while the residence time of carbon 14 in oceans could take thousands of years.
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Upwelling is another phenomenon that dilutes radiocarbon content of surface waters. In certain parts of the globe, the equatorial region in particular, deep waters move up.
This phenomenon is latitude dependent and occurs as a consequence of trade winds. Coastline shape, local climate and wind, and ocean bottom topography also contribute to upwelling. The slow mixing and the upwelling of deep waters mean that the surface water of oceans already have apparent radiocarbon age relative to the atmosphere.
No dating method cited by evolutionists is unbiased. 2. The Wild Dates of Carbon Dating. A few examples of wild dates by radiometric dating: Shells from living snails were carbon dated as being 27, years old. 3; Living mollusk shells were dated up to 2, years old. 4; A freshly killed seal was carbon dated as having died 1, years ago. 5. Dec 14, "Living snails were carbon dated at 2, and 27, years old, showing that the dating method is invalid. "This is not a logical statement. One data .
Freshwater shells may not be affected by the marine reservoir effect, but they are susceptible to the hard water effect-the presence of calcium ions resulting from the dissolution of infinite-age calcium carbonate.
The presence of calcium ions coincides with carbon depletion although the magnitude of the hard water effect is not directly correlated with the amount of calcium ions.
This effect causes the ages of samples to appear older than they actually are due to the incorporation of older CaCO3 that has been dissolved into the freshwater source from substances like limestone or marl that the lake or streams move through. This is sometimes tested by dating living shells in the same area to see if they yield modern results or older results.
This bias can be on the order of a few decades to several hundred years depending on different factors. Hard water effect can also affect marine shells deposited in areas where there is an influx of carbonate-rich freshwater like in river mouths.
Terrestrial shells, like snail shell, are also affected by the hard water effect in cases when the organism has been feeding on carbonate-rich areas like a chalkland. AMS lab analysts must know the reservoir effects that could affect any given shell sample so they will know the age offsets needed.
Radiocarbon Dating Shells. Shells are often sent to accelerator mass spectrometry (AMS) labs for radiocarbon dating. A great proportion of shell materials sent to AMS labs for carbon 14 dating are mollusk shells. Shells are not easy to radiocarbon date; there are many factors that contribute uncertainties to the results. Carbon dating is based on the assumption that the amount of C14 in the atmosphere has always been the same. But there is more carbon in the atmosphere now than there was 4 thousand years ago. (1) Since carbon dating measures the amount of carbon still in a fossil, then the date given is not accurate. Carbon contents as low as +/- percent modern (apparent age, 27, years) measured from the shells of snails Melanoides tuberculatus living in artesian springs in southern Nevada are attributed to fixation of dissolved HCO 3-with which the shells are in carbon isotope equilibrium.
AMS labs quantify the marine and hard water reservoir effects by assuming there has been no change in radiocarbon content and by dating known-age shells of the same species from the same locality that have been collected before the nuclear weapons testing of the s and s.
Depending on the age of the marine carbonate, a to year correction i.
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This automatic correction means the radiocarbon date gets more recent in time due to the fact that it takes years for present-day carbon dioxide in the atmosphere to be incorporated and distributed equilibrated through the ocean water column. Note: A negative Delta-R will make the date older typically presuming freshwater dilution from the global marine average.
The local environment of an organism assimilating the carbon is one of the factors to be considered before subjecting the sample to accelerator mass spectrometry radiocarbon dating. AMS lab analysts must know the types of contaminants the shell samples could have been exposed to.
Any carbon-containing substance that can change the carbon 14 content of a shell sample upon contact is a contaminant. This means that calcium carbonate, soil humic materials, and soil carbon dioxide are potential contaminants.
The most common contaminants of shell samples for radiocarbon dating are those that are caused by isotopic exchange and recrystallization. AMS labs perform pretreatment before carbon 14 dating to remove all possible contaminants that would lead to inaccurate results.
Either an acid etchsonication in alkali or no pretreatment. Given enough material, the lab typically etches off the outer half of the shell to eliminate any potential secondary carbonate.
Living penguins have been carbon dated and the results said that they had died 8, years ago! This is just one of many inaccurate dates given by Carbon dating.
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The shells of living mollusks have been dated using the carbon 14 method, only to find that the method gave it a date as having been dead for 23, years! Science vol. The body of a seal that had been dead for 30 years was carbon dated, and the results stated that the seal had died 4, years ago!
What about a freshly killed seal?
Radiometric Dating: Carbon-14 and Uranium-238
Well, they dated one of those too, the results stated that the seal had died 1, years ago. Antarctic Journal vol.
Consequently organisms living there dated by C14 give ages much older than their true age.