The field of radiocarbon dating has become a technical one far removed fromthe naive simplicity which characterized its initial introduction by Libbyin the late 1940's. It is, therefore, not surprising that manymisconceptions about what radiocarbon can or cannot do and what it has orhas not shown are prevalent among creationists and evolutionists—laypeople as well as scientists not directly involved in this field. In thefollowing article, some of the most common misunderstandings regardingradiocarbon dating are addressed, and corrective, up-to-date scientificcreationist thought is provided where appropriate.
MYTH #1. Radiocarbon is used to date the age of rocks, which enablesscientists to date the age of the earth.
Radiocarbon is not used to date the age of rocks or to determine the age ofthe earth. Other radiometric dating methods such as potassium-argon orrubidium-strontium are used for such purposes by those who believe that theearth is billions of years old. Radiocarbon is not suitable for this purposebecause it is only applicable: a) on a time scale of thousands of years andb) to remains of once-living organisms (with minor exceptions, from whichrocks are excluded).
MYTH #2 Radiocarbon dating has established the date of some organicmaterials (e.g., some peat deposits) to be well in excess of 50,000 years,thus rendering a recent creation (6 to 10 thousand years ago) impossible.
Some organic materials do give radiocarbon ages in excess of 50,000"radiocarbon years." However, it is important to distinguish between"radiocarbon years" and calendar years. These two measures of time will onlybe the same if all of the assumptions which go into the conventionalradiocarbon dating technique are valid. Comparison of ancient, historicallydated artifacts (from Egypt, for example) with their radiocarbon dates hasrevealed that radiocarbon years and calendar years are not the same even forthe last 5,000 calendar years. Since no reliable historically datedartifacts exist which are older than 5,000 years, it has not been possibleto determine the relationship of radiocarbon years to calendar years forobjects which yield dates of tens of thousands of radiocarbon years. Thus,it is possible (and, given the Flood, probable) that materials which giveradiocarbon dates of tens of thousands of radiocarbon years could have trueages of many fewer calendar years.
MYTH #3. The shells of live freshwater clams have been radiocarbon dated inexcess of 1600 years old, clearly showing that the radiocarbon datingtechnique is not valid.
The shells of live freshwater clams can, and often do, give anomalousradiocarbon results. However, the reason for this is understood and theproblem is restricted to only a few special cases, of which freshwater clamsare the best-known example. It is not correct to state or imply from thisevidence that the radiocarbon dating technique is thus shown to be generallyinvalid.
The problem with freshwater clams arises because these organisms derive thecarbon atoms which they use to build their shells from the water in theirenvironment. If this water is in contact with significant quantities oflimestone, it will contain many carbon atoms from dissolved limestone. Sincelimestone contains very little, if any, radiocarbon, clam shells willcontain less radiocarbon than would have been the case if they had gottentheir carbon atoms from the air. This gives the clam shell an artificiallyold radiocarbon age.
This problem, known as the "reservoir effect," is not of very greatpractical importance for radiocarbon dating since most of the artifactswhich are useful for radiocarbon dating purposes and are of interest toarchaeology derive from terrestrial organisms which ultimately obtain theircarbon atoms from air, not the water.
MYTH #4. Samples of coal have been found with radiocarbon ages of only20,000 radiocarbon years or less, thus proving the recent origin of fossilfuels, probably in the Flood.
I am not aware of any authentic research which supports this claim. Also, itdoes not coincide with what creationist scientists would currentlyanticipate based upon our understanding of the impact of the Flood onradiocarbon.
It is not difficult to see how such a claim could arise, however. There aretwo characteristics of the instrumental measurement of radiocarbon which, ifthe lay observer is unaware, could easily lead to such an idea.First, any instrument which is built to measure radiocarbon has a limitbeyond which it cannot separate the signal due to radiocarbon in the samplefrom the signal due to background processes within the measuring apparatus.Even a hypothetical sample containing absolutely no radiocarbon willregister counts in a radiocarbon counter because of background signalswithin the counter. In the early days of radiocarbon analysis this limit wasoften around 20,000 radiocarbon years. Thus, all the researcher was able tosay about samples with low levels of radiocarbon was that their age wasgreater than or equal to 20,000 radiocarbon years (or whatever thesensitivity limit of his apparatus was). Some may have mistaken this to meanthat the sample had been dated to 20,000 radiocarbon years.
The second characteristic of the measurement of radiocarbon is that it iseasy to contaminate a sample which contains very little radiocarbon withenough radiocarbon from the research environment to give it an apparentradiocarbon age which is much less than its actual radiocarbon age. Forexample, a sample with a true radiocarbon age of 100,000 radiocarbon yearswill yield a measured radiocarbon age of about 20,000 radiocarbon years ifthe sample is contaminated with a weight of modern carbon of just 5% of theweight of the sample's carbon. It is not too difficult to supplycontaminating radiocarbon since it is present in relatively highconcentrations in the air and in the tissues of all living things includingany individuals handling the sample. For this reason special precautionsneed to be exercised when sampling materials which contain only smallamounts of radiocarbon.
Reports of young radiocarbon ages for coal probably all stem from amisunderstanding of one or both of these two factors. Measurements madeusing specially designed, more elaborate apparatus and more astutesampling-handling techniques have yielded radiocarbon ages for anthracitegreater than 70,000 radiocarbon years, the sensitivity limit of thisequipment.
MYTH #5. Continuous series of tree-ring dated wood samples have beenobtained for roughly the past 10,000 years which give the approximatecorrect radiocarbon age, demonstrating the general validity of theconventional radiocarbon dating technique.
Several long tree-ring chronologies have been constructed specifically foruse in calibrating the radiocarbon time scale. By radiocarbon dating a pieceof wood which has been dated by counting the annual growth rings of treesback to when that piece of wood grew, a calibration table can be constructedto convert radiocarbon years to true calendar years. Of course, the table,so constructed, will only give the correct calibration if the tree-ringchronology which was used to construct it had placed each ring in the truecalendar year in which it grew.
Long tree-ring chronologies are rare (there are only two that I am aware ofwhich are of sufficient length to be of interest to radiocarbon) anddifficult to construct. They have been slowly built up by matching ringpatterns between trees of different ages, both living and dead, from a givenlocality. As one might expect, the further back the tree-ring chronologyextends, the more difficult it becomes to locate ancient tree specimens withwhich to extend the chronology. To alleviate this problem it seems, from thepublished literature, to be a common practice to first radiocarbon date alarge number of potential tree specimens and then select those withappropriate radiocarbon age for incorporation into the tree-ring chronology.Such a procedure introduces a bias into the construction of the tree-ringchronology for the earliest millennia which could possibly obscure anyunexpected radiocarbon behavior.
It is not clear to what extent this circular process has influenced thefinal tree-ring calibrations of radiocarbon. Efforts by creationistscientists to obtain the raw data from which the oldest tree-ring chronologyhas been constructed to investigate this possible source of bias have so farnot met with success. Until the raw data does become available for generalscrutiny, creationists are clearly justified in maintaining a high degree ofskepticism.
In any event, the calibration tables which have been produced from treerings do not support the conventional steady-state model of radiocarbonwhich Libby introduced. Rather, they lend support to the idea thatsignificant perturbations to radiocarbon have occurred in the past.
MYTH #6. Creationists are only interested in debunking radiocarbon.
Creationists are interested in the truth. This involves exposing areas ofweakness and error in the conventional interpretation of radiocarbon resultsas well as suggesting better understandings of radiocarbon congruent with aBiblical, catastrophist, Flood model of earth history. At ICR research intoalternative interpretations of radiocarbon which are not in conflict withthe Biblical record of the past continue to be actively pursued and aspecial radiocarbon laboratory is being developed for research into themethod.
Radiocarbon holds unique potential for the student of earth history whoadheres to a recent creation. It is doubtful that other radiometric datingtechniques such as potassium-argon or rubidium-strontium will ever be ofmuch value or interest to the young-earth creationist who desires to developfurther our understanding of the past because they are only applicable on atime scale of millions or billions of years. Radiocarbon, however, isapplicable on a time scale of thousands of years. A proper understanding ofradiocarbon will undoubtedly figure very significantly into the unravelingof such questions as when (and possibly why) the mammoths became extinct,the duration of the glacial period following the Flood, and the generalchronology of events from the Flood to the present.
Creationists are not so much interested in debunking radiocarbon as we arein developing a proper understanding of it to answer many of our ownquestions regarding the past. At the present time it appears that theconventional radiocarbon dating technique is on relatively firm ground fordates which fall within the past 3,000 years. For periods of time prior tothis, there are legitimate reasons to question the validity of theconventional results and seek for alternative interpretations.
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