Archaeology and the Bible
Carbon-14 Dating
Most people, I think, are acquainted with the phenomenon of radioactivity, but at the risk of boring any scientists reading these pages, allow me to recap.
Atoms are made up of positive particles called protons and negative particles called neutrons (there are also neutral particles called neutrons, but let's not complicate matters). When there are an equal number of positive and negative particles the atom is stable, but if there is an excess of one or the other, the atom is unstable and sooner or later it is going to "decay" by ejecting a particle or some energy in the form of a gamma ray.
"Decay" takes three forms: gamma rays, alpha particles or beta particles. Beta particles are simply a single electron. Alpha particles are made up of two protons and two neutrons. It can sometimes take a whole chain of decay events before the unstable atom reaches a stable state as a form of lead. Although it is impossible to predict when any particular atom will "decay", when you consider a group of thousands or millions of atoms scientists have found that after a particular period, unique to each element, half of the unstable atoms will have decayed. Oddly enough, after the same period of time again, half the remaining unstable atoms (a quarter of the whole) will have decayed and after the third same period of time, another half the remaining unstable atoms (now an eighth of the whole) will have decayed. This is why that period of time is known as a "half-life".
The length of the half-life varies from element to element. With some elements it is tens of thousands or even millions of years long, in others it is tiny fractions of a second. In the case of carbon-14, the half-life is believed to be around 5730 years long.
Note, however, that these long half-lives are calculated, not observed. We have only known about radio-activity since the early years of the Twentieth Century and have only been able to measure it with any degree of exactness for fifty or sixty years. Scientists believe that the rate of decay has remained constant, but we cannot know that for certain. It may be that decay rates gradually alter over time or undergo some periodic perturbation every so often that reduces the half-life considerably. These things are unlikely, but the point is that we have not known about radio-activity long enough to be sure that nothing like them happens.
Back in 1949 a Dr Willard Libby at the University of Chicago realised that all living things use carbon in their make-up and to the cell, carbon-14 is just as acceptable as its stable cousin, carbon-12. Plants, which provide food at first or second hand for the entire animal kingdom, absorb carbon from the air, so their make-up will reflect the proportion of carbon-14 to carbon-12 in the atmosphere at the time they were alive.
When a plant dies, however, it ceases to take in carbon and therefore its ratio of carbon-14 to carbon-12 is frozen. If you examine it on the day of its death, that ratio will be the same as the present atmospheric ratio, but if you come back and examine it 5730 years later, the level of carbon-14 will have fallen by half - the half-life, remember? - while if you examine it 2865 years after it died, the level of carbon-14 will only have fallen by a quarter - half a half-life.
In theory, therefore, determining the age of a piece of wood is simplicity itself. All you do is measure the ratio of carbon-14 to carbon-12, perform a few simple calculations based on the half-life figure, and tell the world exactly how old it is. Modern instruments are so sensitive that we can measure carbon-14 back to ten half-lives, in other words, back to around 60,000 years ago.
In practice, however, things are not that simple. Over the years scientists have refined the length of the half-life of carbon-14. Libby believed that it was 5568 years; the currently accepted value is 5730, plus or minus 40 years. Oddly, in order to harmonise with earlier results, modern laboratories that engage in carbon-14 dating still use Libby's incorrect value for the half-life of carbon-14 - which does seem a bit like playing fast and loose with the facts!
A further problem is that the ratio of carbon-14 to carbon-12 in the atmosphere is not constant. For example, the ratio has fallen over the last couple of centuries as the Industrial Revolution has poured out thousands of tons of carbon into the atmosphere. In a similar way in the past, volcanoes have been responsible for putting significant amounts of carbon into the air. On the other hand, nuclear weapon tests in the last century have virtually doubled the amount of carbon-14 in the northern hemispere! In order to get an accurate age scientists have had to draw up tables of corrections: if the carbon-14 date is 3,000 years old, the object may in fact be 2,850 years old because of the pollution caused by, for example, an Icelandic volcano.
Dr Libby went to considerable trouble over his table of corrections, comparing samples from Egyptian objects whose date was believed to be secure and inserting the relevant correction into his table. According to the Cambridge Encyclopaedia of Archaeology by the time he reached the Middle Bronze Age, he was using a correction of 600 years - which is the number of years by which our Revised Chronology wishes to adjust the conventional chronology!
Of course scientists are making valiant efforts to improve these correction tables. Ice cores from Greenland, tree ring series from various continents, all are being used to provide correlation and validation for carbon-14 dating. However given that all carbon-14 dates are imprecise - 3,000 years old plus or minus 150 years, for example - one suspects that there is a degree of tweaking to get the results you expect rather than rock-solid confirmation of the theory.
Nowhere is this better seen than in the island of Santorini, an enormous volcano in the Mediterranean, which erupted, ejecting 24 cubic miles of rock and ash into the atmosphere, making the eruption four times larger than that of Krakatoa. The collapse of the caldera is believed to have sent tsunami racing across the Mediterranean which destroyed the Minoan civilisation on Crete, but the amount of material ejected into the upper atmosphere must have had a profound effect on the entire globe.
The problem is, when did this happen? When the island was excavated by Professor Spyridon Marinatos he found Minoan remains buried beneath 200 feet of white ash. By comparing the pottery with that found elsewhere, he dated the eruption to 1500-1450 BC, a fact that led many to suggest that the eruption of Santorini was somehow linked to the plagues of Egypt that preceded the Exodus. However a few years ago an olive tree was found beneath a lava flow associated with the eruption and it was carbon-14 dated to 1627-1600 BC with 95% accuracy.
The problem this has caused for historians is excellently summarised in the article on Wikipedia about the eruption (see the section "Date"). After pointing out that all the scientific evidence points to 1600 BC, the conclusion is:
Although radiocarbon consistently indicates a 1600 BCE eruption dating, some archaeologists still believe that the date is contradicted by findings in Egyptian and Theran excavations. For example, buried Egyptian and Cypriot pottery found on Thera were dated to a later period than the radiometric dates for the eruption, and, since the conventional Egyptian chronology has been established by numerous archaeological studies, the exact date of the eruption remains controversial.
Of course it is the position of this website that Egyptian chronology is not reliable. In fact, it is even less reliable than might appear from that quote, for the radio-carbon date of 1600 is probably not the raw date but the adjusted one (ironically, adjusted with reference to Egyptian chronology!) If that is so, then instead of the eruption occurring at a true date of 1600 BC it may have happened at a true date of 1000 BC - and that would put Middle Bronze IIB at the time of David, a time that would agree very closely with the requirements of the Revised Chronology.
However there is a more serious problem with carbon-14 dating than just imprecision and the contradiction between carbon-14 and Egyptian history, and this problem has to do with the very basis for the theory that underlies radio-active dating.
Carbon-14 is formed by events in the upper atmosphere, so conceivably there was a time when there was no carbon-14. Today the rate of formation is believed to match the rate of decay, so the ratio is more or less stable (volcanoes and Industrial Revolutions aside) and because carbon-14 dating is only reliable back to around 60,000 years, scientists are confident that the ratio has been more or less stable all through that period. After all, 60,000 years is only a very small fraction of the 4.5 billion year age of the earth. Thus their presupposition is a stable ratio of carbon-14 to carbon-12
If, however, we consider for a moment what the situation would be if the earth was only 10,000 years old, we face a very different scenario. In such a scenario, carbon-14 only began to be formed 10,000 years ago, so an object that was 10,000 years old would have zero carbon-14 and would register 60,000 years or more on the carbon-14 clock! As the level of carbon-14 in the atmosphere - and consequently in the plants - rose, so the apparent carbon-14 ages would decrease, but the effect would be that ages before the ratio stabilised would be stretched so as to appear longer than they really were.
It has been argued that before the Flood the earth was better shielded than it is today from cosmic radiation, so no carbon-14 formed in the atmosphere. After the Flood the level of carbon-14 began to rise until it reached a stable level. However let us consider an object which lived and died during that period when the level of carbon-14 was only half what it is today.
That means that as soon as it was born, our scientists would have concluded that it was 5730 years old! Today, following 5,000 years of decay, it still appears to be 5,730 years older than it really is. Something only a couple of centuries younger might appear to be 3,000 years older than it really is and something a couple of centuries older might appear to be 7,000 years older than it really is.
The Creationist, without in any way disparaging the science for which Libby received a Nobel prize, works from a presupposition of a rising ratio of carbon-14 to carbon-12. He is just as scientific, just as consistent - he merely has a different set of presuppositions. This is why I feel at liberty to doubt the great ages assigned to prehistory. A particular Neolithic city might have been inhabited for four or five centuries, but because of this stretching effect, the carbon-14 dates make it appear to have been inhabited for as many millennia.
Carbon-14 dates are useful for giving us relative ages: we can be pretty certain that an object with less carbon-14 is older than another object which has more carbon-14. What we cannot do with any safety is assign absolute dates to those objects. Even with objects within the historical period and conventionally dated, we need to remember that the carbon-14 dates are "corrected" and "adjusted" and local conditions may have skewed the ratio enough to render the date inaccurate.
I am told that archaeologists who send off half a dozen articles to be carbon-dated commonly receive back a set of dates, some of which may differ widely from the conventional chronology. For example, they may be working in a stratum which has Iron Age pottery, for which the conventional date is 1200 BC. The dates they receive back from three objects may point to 1300 BC, 1200 BC, and 900 BC. All those dates will have a margin of error associated with them - shall we say, plus or minus 75 years. The archaeologists will accept the first two carbon dates, because they are within the margin of error, and simply discard the third on the assumption that it is somehow contaminated. The report on their dig will announce that the date of 1200 BC has been confirmed by carbon-14 dating!
Please note that I am not accusing such archaeologists of dishonesty. Samples do get contaminated and it is not always possible to detect such contamination beforehand. Nevertheless, the fact that anomalous carbon-14 dates are simply discarded does mean that claims of carbon-14 support for the conventional chronology have to be taken with a degree of caution.
carbon-14 It is believed that carbon-14 is produced from nitrgen atoms hit by cosmic rays in the upper atmosphere between 30,000 and 50,000 feet and primarily in the higher latitudes. This cannot be the only source of carbon-14, however, as atmospheric nuclear tests have almost doubled the concentration of carbon-14 in the northern hemispere. It is conceivable, therefore, that natural radiation may have produced carbon-14 by some means not yet understood. Return
Cambridge Encyclopaedia of Archaeology This is what the encyclopaedia says - and note the figure of 600 years. In effect, our Revised Chronology claims that the raw carbon-14 dates are correct and the adjusted dates should be discarded.
"When the radio-carbon method was first tested, good agreement was found between radio-carbon dates and the historical dates for samples of known age (for example, from ancient Egyptian contexts). As measurements became more precise, however, it gradually became apparent that there were systematic discrepancies between the dates that were being obtained and those that could be expected from historical evidence. These differences were most marked in the period before about the mid-first millenium BC, in which radio-carbon dates appeared too recent, by up to several hundred years by comparison with historical dates. Dates for the earliest comparative material available, reeds used as bonding between mud-brick courses of tombs of the Egyptian Dynasty I, about 3100 BC, appeared to be as much as 600 years, or about 12%, too young."
Cambridge Encyclopaedia of Archaeology p. 424
In 2004 David Down, the editor of Diggings magazine, interviewed Professor Lord Colin Renfrew of Cambridge University. During the interview he touched on the question of carbon-14 dating.
DD: Concerning carbon 14 dating, do you feel it is 100 per cent reliable?
CR: Yes, though it cannot be considered to be absolutely precise and it is not unusual for archaeologists during their excavations to misinterpret their findings, and sometimes archaeologists find that radiocarbon dating is not what they expect. If it is possible to get a stratigraphic sequence of a site by radiocarbon dating, it is of great assistance. I m afraid there are some archaeological traditions where people don't like things that don't agree with their preconceptions. I don't know of any serious archaeologist who disputes the general validity of radiocarbon dating.
DD: In your University lectures do you deal with the question of chronology? In particular concerning the revision of dates at the time of the TIP (Third Intermediate Period)?
CR: The revision has taken place. I quite agree with what we said earlier, although we still have to study the details of about 1000 BC. But the broader picture of the overthrow of the diffusionist chronology, and the acceptance of chronology based on radiocarbon dating has been accepted, and that is lectured on not only by me but every lecturer in the University will say those things.
My understanding is - and I am open to correction on this point - that Lord Renfrew was advocating the unadjusted carbon-14 dates. Return
more or less stable Note that this is an assumption. In fact, as noted above, what has been observed, as opposed to what the theory requires, is a changing ratio of carbon-14 to carbon-12 owing to industrialisation and atomic bomb tests. It is entirely possible that the ratio is not at all stable and has been rising all through history and will continue to rise for some time to come on top of the anomalies caused by the factors mentioned. Return
began to rise Scientists claim that such a rapid rise is impossible as the amount of cosmic radiation require to produce so much carbon-14 would wipe out life on earth. I'm not about to argue with the experts; I'll merely suggest that if the scientists saw a need to explain such a rise they are ingenious enough to come up with an explanation - perhaps a reservoir of irradiated carbon-14 gas being released? Return
