Background
People who ask about carbon-14 (14C) dating usually want to know about the radiometric (also known as isotope or radioisotope) dating methods that are claimed to give millions and billions of years – carbon dating can only give thousands of years.
Technical data
Carbon has unique properties that are essential for life on Earth. Familiar to us as the black substance in charred wood, as diamonds, and the graphite in ‘lead’ pencils, carbon comes in several forms, or isotopes. One rare form has atoms that are 14 times as heavy as hydrogen atoms: carbon-14, or 14C, or radiocarbon.
Carbon-14 is made when cosmic rays knock neutrons out of atomic nuclei in the upper atmosphere. These displaced neutrons, now moving fast, hit ordinary nitrogen (14N) at lower altitudes, converting it into 14C. Unlike common carbon (12C), 14C is unstable and slowly decays, changing back into nitrogen and releasing energy. This instability makes it radioactive.
Ordinary carbon (12C) is found in the carbon dioxide (CO2) in the air, which is taken up by plants, which in turn are eaten by animals. So a bone, or a leaf of a tree, or even a piece of wooden furniture, contains carbon. When 14C has been formed, like ordinary carbon (12C), it combines with oxygen to give carbon dioxide (14CO2), and so it also gets cycled through the cells of plants and animals. We can take a sample of air, count how many 12C atoms there are for every 14C atom, and calculate the 14C/12C ratio. Because 14C is so well mixed up with 12C, we expect to find that this ratio is the same if we sample a leaf from a tree, or a part of your body. In living things, although 14C atoms are constantly changing back to 14N, they are still exchanging carbon with their surroundings, so the mixture remains about the same as in the atmosphere. However, as soon as a plant or animal dies, the 14C atoms which decay are no longer replaced, so the amount of 14C in that once-living thing decreases as time goes on (Figure 1). In other words, the 14C/12C ratio gets smaller. So, we have a ‘clock’ which starts ticking the moment something dies.
Obviously this works only for things that were once living. It cannot be used to date volcanic rocks, for example. The rate of decay of 14C is such that half of an amount will convert back to 14N in 5,730 +/- 40 years. This is the ‘half-life’. So, in two half-lives, or 11,460 years, only one-quarter will be left. Thus if the amount of 14C relative to 12C in a sample is one-quarter of that in living organisms at present, then it has a theoretical age of 11,460 years. Anything over about 50,000 years old, should theoretically have no detectable 14C left. That is why radiocarbon dating cannot give millions of years. In fact, if a sample contains 14C, it is good evidence that it is not millions of years old.
However, things are not quite so simple - Firstly, plants discriminate against carbon dioxide containing 14C. That is, they take up less than would be expected and so they test older than they really are. Furthermore, different types of plants discriminate differently. This also has to be corrected for. (Today, a stable carbon isotope, 13C, is measured as an indication of the level of discrimination against 14C.)
Secondly, the ratio of 14C/12C in the atmosphere has not been constant – for example it was higher before the industrial era when the massive burning of fossil fuels released a lot of carbon dioxide that was depleted in 14C. This would make things which died at that time appear older in terms of carbon dating. Then there was a rise in 14CO2 with the advent of atmospheric testing of atomic bombs in the 1950s. (Radiation from atomic testing, like cosmic rays, causes the conversion of 14N to 14C.) This would make things carbon-dated from that time appear younger than their true age.
Measurements of 14C in historically dated objects (e.g. seeds in the graves of historically dated tombs) enable the level of 14C in the atmosphere at that time to be estimated, and so partial calibration of the ‘clock’ is possible. Accordingly, carbon dating carefully applied to items from historical times can be useful. However, even with such historical calibration, archaeologists do not regard 14C dates as absolute because of frequent anomalies. They rely more on dating methods that link into historical records. Outside the range of recorded history, calibration of the 14C ‘clock’ is not possible.
Other factors affecting carbon dating
The amount of cosmic rays penetrating Earth’s atmosphere affects the amount of 14C produced and therefore the dating system. The amount of cosmic rays reaching the earth varies with the sun’s activity, and with the earth’s passage through magnetic clouds as the solar system travels around the Milky Way galaxy.
The strength of the earth’s magnetic field affects the amount of cosmic rays entering the atmosphere. A stronger magnetic field deflects more cosmic rays away from the earth. Overall, the energy of the earth’s magnetic field has been decreasing, 1 so more 14C is being produced now than in the past. This will make old things look older than they really are.
Effects from a Global Flood
(see also topic : Is there really any evidence of a Global Flood )
The Flood buried a huge amount of carbon, which became coal, oil, etc., lowering the total 12C in the biosphere (including the atmosphere – plants re-growing after the Flood absorb CO2 which is not replaced by the decay of the buried vegetation). Total 14C is also proportionately lowered at this time, but whereas no terrestrial process generates any more 12C, 14C is continually being produced, and at a rate which does not depend on carbon levels (it comes from nitrogen). Therefore the 14C level relative to 12C increases after the Flood. So the 14C/12C ratio in plants/animals/the atmosphere before the Flood had to be lower than what it is now. Unless this effect (which is additional to the magnetic field issue just discussed) were corrected for, carbon dating of fossils formed in the Flood would give ages much older than the true ages.
Also, volcanoes emit much CO2 depleted in 14C. Since the Flood was accompanied by much volcanism, fossils formed in the early post-Flood period would give radiocarbon ages older than they really are.
Other Radiometric dating methods – There are various other radiometric dating methods used today to give ages of millions or billions of years for rocks. These techniques, unlike carbon dating, mostly use the relative concentrations of parent and daughter products in radioactive decay chains. For example, potassium-40 decays to argon-40, uranium-238 decays to lead-206 via other elements like radium, uranium-235 decays to lead-207, rubidium-87 decays to strontium-87, etc. These techniques are applied to igneous rock, and are normally seen as giving the time since solidification.
The isotope concentrations can be measured very accurately, but isotope concentrations are not dates. To derive ages from such measurements, un-provable assumptions have to be made (see hourglass diagram below) such as,
The starting conditions are known (for example, that there was no daughter isotope present at the start, or that we know how much was there).
Decay rates have always been constant.
Systems were closed or isolated so that no parent or daughter isotopes were lost or added.
The hourglasses represent radiometric dating. It is assumed that we know the amount of parent and daughter elements in the original sample, the rate of decay is constant, and no parent or daughter material has been added or removed.
There is plenty of evidence that the radioisotope dating systems are not the infallible techniques many think, and that they are not measuring millions of years. However, there are still patterns to be explained. For example, deeper rocks often tend to give older ‘ages’. Creationists agree that the deeper rocks are generally older, but not by millions of years. Geologist John Woodmorappe, in his devastating critique of radioactive dating,2 points out that there are other large-scale trends in the rocks that have nothing to do with radioactive decay.
‘Bad’ Dates? – When a ‘date’ differs from that expected, researchers readily invent excuses for rejecting the result. The common application of such posterior reasoning shows that radiometric dating has serious problems. Woodmorappe cites hundreds of examples of excuses used to explain ‘bad’ dates.
For example, researchers applied posterior reasoning to the dating of Australopithecus ramidus fossils.3 Most samples of basalt closest to the fossil-bearing strata gave dates of about 23 Ma (Mega annum, million years) by the argon-argon method. The authors decided that was ‘too old’ according to their belief about the place of the fossils in the evolutionary grand scheme of things. So they looked at some basalt further removed from the fossils and selected 17 of 26 samples to get an acceptable maximum age of 4.4 Ma. The other nine samples again gave much older dates but the authors decided they must be contaminated and discarded them. That is how radiometric dating works. It is very much driven by the existing long-age worldview that pervades academia today.
A similar story surrounds the dating of the primate skull known as KNM-ER 1470.4,5 This started with an initial 212 to 230 Ma, which, according to the fossils, was considered way off the mark (humans ‘weren’t around then’). Various other attempts were made to date the volcanic rocks in the area. Over the years an age of 2.9 Ma was settled upon because of the agreement between several different published studies (although the studies involved selection of ‘good’ from ‘bad’ results, just like Australopithecus ramidus, above).
However, preconceived notions about human evolution could not cope with a skull like 1470 being ‘that old’. A study of pig fossils in Africa readily convinced most anthropologists that the 1470 skull was much younger. After this was widely accepted, further studies of the rocks brought the radiometric age down to about 1.9 Ma – again several studies ’confirmed’ this date. Such is the dating game.
Are we suggesting that evolutionists are conspiring to massage the data to get the answer they want? No, not generally. It is simply that all observations must fit the prevailing paradigm. The paradigm, or belief system, of molecules-to-man evolution over eons of time, is so strongly entrenched it is not questioned – it is ‘fact’. So every observation must fit this paradigm. Unconsciously, the researchers, who are supposedly ‘objective scientists’ in the eyes of the public, select the observations to fit the basic belief system.
We must remember that the past is not open to the normal processes of experimental science, that is, repeatable experiments in the present. A scientist cannot do experiments on events that happened in the past. Scientists do not measure the age of rocks, they measure isotope concentrations, and these can be measured extremely accurately. However, the ‘age’ is calculated using assumptions about the past that cannot be proven.
Williams, an expert in the environmental fate of radioactive elements, identified 17 flaws in the isotope dating reported in just three widely respected seminal papers that supposedly established the age of the earth at 4.6 billion years.6 John Woodmorappe has produced an incisive critique of these dating methods.2 He exposes hundreds of myths that have grown up around the techniques. He shows that the few ‘good’ dates left after the ‘bad’ dates are filtered out could easily be explained as fortunate coincidences.
What date would you like? – The forms issued by radioisotope laboratories for submission with samples to be dated commonly ask how old the sample is expected to be. Why? If the techniques were absolutely objective and reliable, such information should not be necessary . Presumably the laboratories know that anomalous dates are common, so they need some check on whether they have obtained a ‘good’ date.
Testing radiometric dating methods – If the long-age dating techniques were really objective means of finding the age of rocks, they should work in situations where we know the age. Furthermore, different techniques should consistently agree with one another.
Methods should work reliably on things of known age – There are many examples where the dating methods give ‘dates’ that are wrong for rocks of known age. One example is K-Ar ‘dating’ of five historical andesite lava flows from Mt Ngauruhoe in New Zealand. Although one lave flow occurred in 1949, three in 1954, and one in 1975, the ‘dates’ ranged from less than 0.27 to 3.5 Ma.7
Again, using hindsight, it is argued that ‘excess’ argon from the magna (molten rock) was retained in the rock when it solidified. The secular scientific literature lists many examples of excess argon causing dates of millions of years in rocks of known historical age.8 This excess appears to have come from the upper mantle, below the earth’s crust. This is consistent with a young world – the argon has had too little time to escape.9 If excess argon can cause exaggerated dates for rocks of known age, then why should we trust the method for rocks of unknown age?
Other techniques, such as the use of isochrones,10 make different assumptions about starting conditions, but there is a growing recognition that such ‘fool-proof’ techniques can also give ‘bad’ dates. So data are again selected according to what the researcher already believes about the age of the rock.
Geologist Dr Steve Austin sampled basalt from the base of the Grand Canyon strata and from lava that spilled over the edge of the canyon.11 By evolutionary reckoning, the latter should be a billion years younger than the basalt from the bottom. Standard laboratories analysed the isotopes. The rubidium-strontium isochron technique suggested that the recent lava flow was 270 Ma older than the basalts beneath the Grand Canyon – an impossibility.
Different dating techniques should consistently agree – If the dating methods are an objective and reliable means of determining ages, they should agree. If a chemist were measuring the sugar content of blood, all valid methods for the determination would give the same answer (within the limits of experimental error). However, with radiometric dating, the different techniques often give quite different results.
In the study of Grand Canyon rocks by Austin,11 different techniques gave different results (see table below). Again all sorts of reasons can be suggested for the ‘bad’ dates, but this is again posterior reasoning. Techniques that give results that can be dismissed just because they don’t agree with what we already believe cannot be considered objective.
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In Australia, some wood found in Tertiary basalt was clearly buried in the lava flow that formed the basalt, as can from the charing. The wood was ‘dated’ by radiocarbon (14C) analysis at about 45,000 years old, but the basalt was ‘dated’ by the potassium-argon method at 45 million years old!12
More evidence something is wrong
14C in fossils supposedly millions of years old - Carbon dating in many cases seriously embarrasses evolutionists by giving ages that are much younger than those expected from their model of Earth history. A specimen older than 50,000 years should have too little 14C to measure.
Laboratories that measure 14C would like a source of organic material with zero 14C to use as a blank to check that their lab procedures do not add 14C. Coal is an obvious candidate because the youngest coal is supposed to be millions of years old, and most of it is supposed to be 10s or 100s of millions of years old. Such old coal should be devoid of 14C. It isn’t. No source of coal has been found that completely lacks 14C.
Fossil wood found in ‘Upper Permian’ rock that is supposedly 250 Ma old still contains 14C.21 Recently a sample of wood found in rock classed as ‘middle Triassic’, supposedly some 230 million years old, gave a 14C date of 33,720+/- 430 years.14 The accompanying checks showed that the 14C date was not due to contamination and that the ‘date’ was valid, within the standard (long ages) understanding of this dating system.
It is an unsolved mystery to evolutionists as to why coal has 14C in it,15 or wood supposedly many millions of years old still has 14C present, but it makes perfect sense in a creationist worldview.
What then do the radiometric ‘dates’ of millions of years mean, if they are not true ages? To answer this question, it is necessary to scrutinise further the experimental results from the various dating techniques, the interpretations made on the basis of the results and the assumptions underlying those interpretations.16
The isochron dating technique10 was thought to be infallible because it supposedly covered the assumptions about starting conditions and closed systems.
Geologist Dr Andrew Snelling worked on ‘dating’ the Koongarra uranium deposits in the Northern Territory of Australia, primarily using the uranium-thorium-lead (U-Th-Pb) method. He found that even highly weathered soil samples from the area, which are definitely not closed systems, gave apparently valid ‘isochron’ lines with ‘ages’ of up to 1,445 Ma.
Such ‘false isochrons’ are so common that a whole terminology has grown up to describe them, such as apparent isochron, mantle isochron, pseudoisochron, secondary isochron, inherited isochron, erupted isochron, mixing line and mixing isochron. Zheng Wrote:
‘… some of the basic assumptions of the conventional Rb-Sr [rubidium-strontium] isochron does not certainly define valid age information for a geological system, even if a goodness of fit of the experimental results is obtained in plotting 87Sr/86Sr against 87Rb/86Sr. This problem cannot be overlooked, especially in evaluating the numerical time scale. Similar questions can also arise in applying Sm-Nd [samarium-neodymium] and U-Pb [uranium-lead] isochron methods.’17
Clearly, there are factors other than age responsible for the straight lines obtained from graphing isotope ratios. Again, the only way to know if an isochron is ‘good’ is by comparing the result with what is already believed.
Conclusion
There are many lines of evidence that the radiometric dates are not the objective evidence for an old Earth that many claim, and that the world is really only thousands of years old.
Batten D., Ham K., Sarfati J., Wieland C., The Answers Book
1. McDonald, K.L. and Gunst, R.H., 1965. An analysis of the earth’s magnetic filed from 1835 to 1965. ESSA Technical report IER 46-IES, U.S. Government Printing Office, Washington, D.C., p. 14.
2. Woodmorappe, J., 1999. The Mythology of Modern Dating Methods, Institute for creation Research, San Diego, California.
3. Wolde Gabriel, G., et al., 1994. Ecological and temporal placement of early Pliocene hominids at Aramis, Ethiopia. Nature 371:330-333
4. Lubenow, M., 1995. The pigs took it all. Creation 17(3): 36-38
5. Lubenow, M., 1993. Bones of contention, Baker Books, Grand Rapids, Michigan, pp. 247-266
6. Williams, A.R., Long-age isotope dating short on credibility. CEN Technical Journal 6(1): 2-5.
7. Snelling, A.A., 1998. The cause of anomalous potassium-argon ‘ages’ for recent andesite flows at Mt. Ngauruhoe, New Zealand, and the implications for potassium-argon ‘dating’. Proc. 4th ICC, pp. 503-525.
8. Ref. 7, list many instances. For example, six cases were reported by Krummenacher, D., 1970. Isotopic composition of argon in modern surface rocks. Earth and Planetary Science Letters 8:109-117; five were reported by Dalrymple, G.B., 1969. 40At/36Ar analysis of historic lava flows. Earth and Planetary Science Letters 6: 47-55. A large excess was reported in Fisher, D.E., 1970. Excess rare gases in a subaerial basalt from Nigeria, Nature 232:60-61
9. Ref. 7,p. 520
10. The isochron technique involves collecting a number of rock samples from different parts of the rock unit being dated. The concentration of a parent radioactive isotope, such as rubidium-87, is graphed against the concentration of a daughter isotope, such as strontium-87, for all the samples. A straight line is drawn through these points, representing the ratio of the parent:daughter, from which a ‘date’ is calculated. If the line is of good fit and the ‘age’ is acceptable it is considered a ‘good’ date. The method involves dividing both the parent and daughter concentrations by the concentration of a similar stable isotope – in this case, strontium-86.
11. Austin, S.A. (ed.) 1994 Grand Canyon: Monument to Catastrophe. Institute for creation Research, Santee, California, pp. 120-131
12. Snelling, A.A.,1998. Radiometric dating in conflict. Creation 20(1):24-27.
13. Maas, R., 1989. Nd-Sr isotope constraints on the age and origin of unconformity-type uranium deposits in Alligator Rivers Uranium Field, Northern Territory, Australia. Economic Geology 84:64-90
14. Snelling, A.A., 1999. Dating dilemma. Creation 21(3):39-41
15. Lowe, D.C., 1989. Problems associated with the use of coal as a source of 14C free background material. Radiocarbon 31:117-120
16. See Woodmorappe, Ref. 2, for one such thorough evaluation.
17. Zheng, Y.F., 1989. Influence of the narture of initial Rb-Sr system on isochron validity. Chemical Geology 80:1-16 (p. 14)