Learning from creationists; radiocarbon dating | Primate's Progress
Radiocarbon dating can easily establish that humans have been on the earth for over twenty thousand Therefore it should come as no surprise that creationists at the Institute for Creation Research (ICR) have How do you explain this?. The above is offered as a simple fact of research. Knowing how faulty creationist " facts" can be, let's do a little research of our own. That is, we can use carbon dating on a given tree-ring (the year sequence having been assembled. With our focus on one particular form of radiometric dating—carbon Genesis 1 defines the days of creation to be literal days (a number with the word Is the explanation of the data derived from empirical, observational.
Of course, some species of tree tend to produce two or more growth rings per year. But other species produce scarcely any extra rings. Most of the tree-ring sequence is based on the bristlecone pine. This tree rarely produces even a trace of an extra ring; on the contrary, a typical bristlecone pine has up to 5 percent of its rings missing.
Concerning the sequence of rings derived from the bristlecone pine, Ferguson says: In the growth-ring analyses of approximately one thousand trees in the White Mountains, we have, in fact, found no more than three or four occurrences of even incipient multiple growth layers. Hence at least some of the missing rings can be found. Even so, the missing rings are a far more serious problem than any double rings.
Other species of trees corroborate the work that Ferguson did with bristlecone pines. Before his work, the tree-ring sequence of the sequoias had been worked out back to BC. The archaeological ring sequence had been worked out back to 59 BC. The limber pine sequence had been worked out back to 25 BC. The radiocarbon dates and tree-ring dates of these other trees agree with those Ferguson got from the bristlecone pine. But even if he had had no other trees with which to work except the bristlecone pines, that evidence alone would have allowed him to determine the tree-ring chronology back to BC.
See Renfrew for more details. So, creationists who complain about double rings in their attempts to disprove C dating are actually grasping at straws. If the Flood of Noah occurred around BC, as some creationists claim, then all the bristlecone pines would have to be less than five thousand years old. This would mean that eighty-two hundred years worth of tree rings had to form in five thousand years, which would mean that one-third of all the bristlecone pine rings would have to be extra rings.
Creationists are forced into accepting such outlandish conclusions as these in order to jam the facts of nature into the time frame upon which their "scientific" creation model is based. Barnes has claimed that the earth's magnetic field is decaying exponentially with a half-life of fourteen hundred years.
Not only does he consider this proof that the earth can be no older than ten thousand years but he also points out that a greater magnetic strength in the past would reduce C dates. Now if the magnetic field several thousand years ago was indeed many times stronger than it is today, there would have been less cosmic radiation entering the atmosphere back then and less C would have been produced.
Therefore, any C dates taken from objects of that time period would be too high. How do you answer him? Like Cook, Barnes looks at only part of the evidence.
What he ignores is the great body of archaeological and geological data showing that the strength of the magnetic field has been fluctuating up and down for thousands of years and that it has reversed polarity many times in the geological past.
So, when Barnes extrapolates ten thousand years into the past, he concludes that the magnetic field was nineteen times stronger in BC than it is today, when, actually, it was only half as intense then as now. This means that radiocarbon ages of objects from that time period will be too young, just as we saw from the bristlecone pine evidence. But how does one know that the magnetic field has fluctuated and reversed polarity?
Aren't these just excuses scientists give in order to neutralize Barnes's claims? The evidence for fluctuations and reversals of the magnetic field is quite solid.
- How Good Are Those Young-Earth Arguments?
- Radiometric Dating and Creation Science
- Primate's Progress
Bucha, a Czech geophysicist, has used archaeological artifacts made of baked clay to determine the strength of the earth's magnetic field when they were manufactured. He found that the earth's magnetic field was 1. See Bailey, Renfrew, and Encyclopedia Britannica for details.
In other words, it rose in intensity from 0. Even before the bristlecone pine calibration of C dating was worked out by Ferguson, Bucha predicted that this change in the magnetic field would make radiocarbon dates too young. This idea [that the fluctuating magnetic field affects influx of cosmic rays, which in turn affects C formation rates] has been taken up by the Czech geophysicist, V.
Bucha, who has been able to determine, using samples of baked clay from archeological sites, what the intensity of the earth's magnetic field was at the time in question. Even before the tree-ring calibration data were available to them, he and the archeologist, Evzen Neustupny, were able to suggest how much this would affect the radiocarbon dates.
There is a good correlation between the strength of the earth's magnetic field as determined by Bucha and the deviation of the atmospheric radiocarbon concentration from its normal value as indicated by the tree-ring radiocarbon work. One of the lies you were probably told at school is that all isotopes of the same element have precisely the same chemical properties.
This is not true, and generally speaking, heavier isotopes are slightly more sluggish in their chemical reactions. These North Ronaldsay sheep, which feed on seaweed, will show different isotopic fraction from sheep fed on grass This effect has been measured for photosynthesis. Carbon dioxide in plants is, as expected, slightly depleted in carbon relative to carbon, and the effect is far from trivial; around 27 thousands of carbon abundance for most kinds of plant.
We expect the effect to be twice as large for carbon, which, using the known year halflife of carbon, corresponds to years; not trivial when dating historical artefacts. However, exactly the same effect will apply to the material used to set up the calibration, and the errors will systematically cancel out. Ideally, the fractional abundance of carbon should be measured, as well as that of carbon, to calibrate out any minor fractionation effects, and this is less arduous than it sounds because nowadays carbon abundance is measured by direct counting in a mass spectrometer rather than, as in the original studies, indirectly inferred from sample radioactivity.
For plants, it is straightforward to match like with like. Not so for material derived from animals, where the total amount of isotopic fractionation will depend on their diets, and also on what they have been eating. However, as already explained, we now have direct calibration back to 52, years before present, beyond which the amount of remaining carbon is so small that using current techniques the method becomes useless. If carbon had been buried in the flood, the appropriate amount of carbon would have been buried with it.
And the ideas of a changed rate of production or decay have been dealt with under 1 and 2 above. I have discussed this before. And marine specimens will always contain less carbon than terrestrial specimens of the same age, because of the time it takes for mixing between the atmosphere and surface waters, and again between surface waters and the depths. The first, and most difficult, thing is to realise that he is been perfectly sincere. He is certain that his reading of the Bible is true; but the facts of geology are also true; and it is therefore his mission to create an account that reconciles the two.
If this means the mountains must have skipped like rams, then that is how they must have skipped. He will feel no more absurd at this point, than the cosmologist feels in invoking a time when our Universe was smaller than a tennis ball and its temperature was trillions of degrees. Counter-arguments will be dismissed as so many minor anomalies that will no doubt be explained away in due course.
If the creationist repeats long-refuted claims, that is because he believes that there are refutations of the refutation, even if he cannot immediately call them to mind, or does not have time to explain them properly. With at least one notable exception on the books, plants and animals get their carbon from the atmosphere.
Plants take it in directly, and animals eat the plants. Thus, it gets passed up the food chain. It is not surprising, therefore, to find that the carbon in living plants and animals is in reasonable equilibrium with the atmospheric carbon Some creationists, however, have claimed that certain plants can reject carbon in favor of carbon Because of the chemical similarity of carbon and carbon, it is unlikely that such plants could deviate much from the ratio of C to C found in the atmosphere.
Neither freak cases nor small deviations pose much of a problem for radiocarbon dating, which, after all, works well with a wide variety of plant and animal species. Hence, we only have to worry about the initial concentration of C in the atmosphere. Topic R1 shows that the level of C in the atmosphere has not varied appreciably over tens of thousands of years. Therefore, the initial C content is known for any reasonable sample! The notable exception involves certain mollusks, which get much of their carbon from dissolved limestone.
Since limestone is very old it contains very little carbon Thus, in getting some of their carbon from limestone, these mollusks "inherit" some of the limestone's old age! That is, the limestone carbon skews the normal ratio between C and C found in living things. If one dates such mollusks, one must be extra careful in interpreting the data.
Not every mollusk shell presents such problems, and the dating of other material might yield a cross-check. Further study might even allow correction tables. The discovery has strengthened the carbon method, not weakened it!
By the way, shouldn't the creationist be worried over the old, carbon age of the limestone? Why is it that limestone has so little C in it? Partial contamination, say of a block of wood, may affect its different parts to different degrees.
Insect burrows, cracks, and partial decay may allow contamination later on to affect those portions of the sample unequally. However, there are laboratory techniques, often ingenious, for dealing with such problems. If the sample shows evidence of being hopelessly contaminated it is pitched. Some samples, such as a section of a tree trunk, may well contain material of considerably different ages. The interior portion of a tree trunk could easily be several hundred years older than the outer portions.
In summing up this point, we do know within good limits what the initial C was for any reasonable sample. A sample will not have different ratios of carbon unless it has been contaminated or reflects a genuine range of ages. It is very difficult or impossible to prove that a given sample has not been contaminated.
Parent or daughter products could have leached in or out of the sample. In the case of carbon dating, the daughter product is ordinary nitrogen and plays no role in the dating process. We are only interested in tallying the original C still present in the sample, the surviving "parent" isotope. The C that is incorporated in the carbon structure of cellulose and the other structural materials of living plants and animals is not going to do much migrating after burial.
If structural carbon migrated easily there soon wouldn't be any cellulose, lignin, chitin or other structural carbon compounds left in the soil! A piece of wood, for example, would soon turn into a formless cloud of graphite or soot in the soil, with perhaps a little ash marking the original shape! Clearly, that is not something which normally happens.
Residues or solutions which do migrate can usually be washed out of the structural matrix of the sample with various chemicals. To put it another way, we might imagine a piece of buried wood as being something like a sponge.
Answers to Creationist Attacks on Carbon-14 Dating
Any carbon-containing liquid originally possessed by that sponge might well leak over time and be replaced by something else. However, unless the sponge itself disintegrates, the carbon which holds its fibers together must stay put. Thus, by choosing a sample that is structurally intact, one may rule out any significant loss of C If the liquid impurities in our sponge can be washed and squeezed out, or estimated in some way, then we may be able to date the sponge structural component of our sample itself and get a good date even if non-structural carbon had been lost in a manner that would upset the isotope ratio.
A sample, of course, can be contaminated if organic material rich in fresh atmospheric C soaks or diffuses into it. Such contamination may occur in the ground or during the processing of the sample in the laboratory. However, such contamination will make the sample appear younger than its true age.
Consequently, with regards to carbon dating, creationists are barking up the wrong tree on the contamination issue! Laboratories, of course, do have techniques for identifying and correcting contamination. There are various methods of cleaning the material, and the activity of each rinse can be measured. Lab contamination and technique can be checked by running blanks. A careful choice of samples will often minimize contamination. Dating various portions of a sample is another kind of check that may be performed.
Often there are cross-checks. Samples from top to bottom of a peat bog gave reasonable time intervals Science, vol. The calibrated C method confirmed Egyptian records, and most of the Aegean dates which were cross-dated with Egyptian dates were confirmed American Scientist, May-June The marvelous agreement with tree-ring data, after correction for variations in the earth's magnetic field, has already been mentioned. Carbon dating thus presents a deadly challenge to young-earth creationists.
If an old date is reasonably accurate, they're out of business; if an old date is bad due to contamination, then they are still out of business because the true date is most likely older still. It hardly seems fair, but that's the way it is. With that in mind, let's look at a few carbon dates. Egyptian barley samples have been found which date to 17, years old Science, April 7, On page the author explains some of the professional care which stands behind his use of the carbon method.
Radiometric Dating and Creation Science
A wooden walkway buried in a peat bog in England has been dated to about BC by the carbon method Scientific American, Augustp. Odd, that Noah's flood neither destroyed it nor deposited thick sediments on top of it!
Jennifer Hillam of the University of Sheffield and Mike Baillie of Queen's University of Belfast and their colleagues were able to date the walkway by a second method, i. They found out that the walkway, known as the Sweet Track, was built from trees felled in the winter of BC. Pretty close agreement, huh? Stonehenge, as dated by carbon, was built over a period from BC to BC -- long before the Druids came to England.
Astronomer Gerald Hawkins found, after careful computer calculations, that the arrangement of the stones at Stonehenge are aligned with key positions of the sun and moon as they were almost years ago.
Weber,p. Thus, we have another remarkable confirmation of the C method. When did the volcano that destroyed Thera and probably the Minoan culture as well explode? Radiocarbon dating of seeds and wood buried in the ash, done by scientists at the University of Pennsylvania, pointed to no later than BC. Being that this was one of the biggest volcanic eruptions in recorded history, it almost certainly caused worldwide cooling which would, in turn, affect tree growth.
Sure enough, the growth rings among oaks buried in Ireland's bogs show the effect of unusual cooling from BC. Nor was that just an effect of local weather conditions. The bristlecone pines in the White Mountains of California show the same thing.
A third estimate came from studies in Greenland. Thus, we have a remarkable agreement between three different methods, all within two or three percentage points of each other!
Trees buried by the last advance of glacial ice at Two Creeks, Wisconsin were dated at 11, years.
How Good are those Young-Earth Arguments: Radiocarbon Dating
Between those trees, which are buried in Valders red till, and an earlier, deeper layer of till, the Woodfordian gray till, lay the remains of a forest bed! What is a forest, including developed soil and rooted stumps, doing between two advances of ice? That could be an interesting question for someone who believes in only one "ice age. By careful counting and cross-checking he was able to determine that the oldest glacial lakes, which would have formed at the start of the retreat of the ice, were 12, years old.