What About Carbon-14 Dating?
A common question concerning the creation-evolution controversy is “What about carbon-14 dating?” This radiometric dating method appears often in the mass media news, probably because it is usually applied to fossil materials, particularly to those connected with ancient human remains. Many people are interested in what the fossils say, and carbon-14 (abbreviated C-14) dating seems to make them say they once lived ten, twenty, forty or fifty thousand years ago. As the reasoning apparently goes, with all this time available, perhaps evolution actually did take place. In earlier essays we have shown that the process of evolution can really not be demonstrated in the fossil record, nor can it be demonstrated in the world of living things today. But in the popular mind, C-14 dating is associated with an evolutionary history of life. Just how reliable, then, is this radiometric method for estimating the ages of fossils?
First, how does the method work?
High-energy cosmic rays (actually sub-atomic particles) from space continually crash into atoms in the earth’s upper atmosphere. The result of such a collision is a shower of sub-atomic debris, including many neutrons. Neutrons are found in the nuclei of all atoms except ordinary hydrogen atoms. The nucleus of an atom of ordinary hydrogen consists of a single positively charged particle called a proton. The nuclei of all other elements contain both positively charged protons and neutrons, which are neutral and have close to the same mass as do protons. The gas nitrogen makes up about 78% of earth’s atmosphere. Nitrogen atomic nuclei contain 7 neutrons and 7 protons. The 7 positive protons make it a nitrogen atom, and the 7+7 = 14 protons and neutrons give it an atomic mass of 14. It is an atom of nitrogen-14 (N-14). Common carbon atoms (C-12) have 6 protons and 6 neutrons in their nuclei. When a neutron produced by cosmic radiation hits an N-14 nucleus at the right speed, it can knock out a proton and replace it to produce a nucleus having 6 protons and 8 neutrons. The 6 protons make it an isotope of carbon, Carbon-14 (C-14). Carbon-14 is radioactive, decaying by expelling from its nucleus a single negatively charged electron (called a beta particle). This converts a proton into a neutron, so the C-14 becomes an N-14 atom. A quantity of radioactive C-14 decays at such a rate that half of it remains after 5730 years. This is called the half-life of C-14. Atoms of C-14 formed by cosmic rays in the upper atmosphere soon react with oxygen molecules to produce molecules of carbon dioxide (CO2).
How is this information applied to estimating the ages of fossils?
The atmosphere and living things today have roughly one atom of C-14 per trillion atoms C-12. If the carbon of a carbon-containing fossil is analyzed and found to contain only one-half atom of C-14 per trillion atoms of C-12, it is assumed that the organism died one C-14 half-life or 5730 years ago. A ratio of one-fourth C-14 atoms per trillion atoms of carbon would indicate an age since death of two half-lives or 11,460 years.
What are the assumptions of the C-14 method?
In Creation Essay 19 we explained that every dating method for the distant past involves assumptions. If those assumptions cannot be proved to be uniformly correct, the ages obtained are not certain to be correct. The basic assumptions for the C-14 method are: (1) the rate of radioactive decay of C-14 in a fossil organism has been constant; (2) the rate of formation of C-14 in the upper atmosphere has been constant for about 100,000 years; (3) the total circulating inventory of carbon in the atmosphere, in living organisms, in decaying organic matter, in soil and ground waters and in the oceans has remained constant; (4) the mixing of carbon between these different reservoirs has produced a constant equilibrium concentration of C-14 in living organisms and (5) the fossil being dated has neither lost nor gained any carbon since the death of the organism.
Are these assumptions valid? Can all C-14 ages be accepted as correct?
Assumption 1, constancy of decay rate, is probably a good assumption. The other assumptions, however, are problematic at best. Assumptions 2, 3 and 5 are all known not to be correct in many instances. Great care must be taken to assure that samples have gained or lost no carbon. The C-14 method then yields generally reliable results for historically dateable materials back to about 1500 B.C. For dates prior to 1500 B.C., however, there is an increasing error in C-14 ages, making them lower than the age determined by analysis of ancient tree rings. Tree ring wood 8,000 years old by tree ring count yields C-14 ages up to 650 years less. Furthermore, the comparison of C-14 ages with tree-ring ages in the period 1500 B.C. to the present shows that there were definite deviations of C-14 in living things from the present C-14 concentration in living things. Thus, though the tree ring dating method is subject to some potential errors, it is agreed that the C-14 concentration in living things has not been constant for the past 8,000 years. This and other evidence strongly suggest that the rate of cosmic ray production of C-14 has not been constant. Remember that there is no way to prove that it was constant prior to 6000 B.C.
Perhaps some of the deviations in C-14 concentration in living things were the result of variations in the rate of cosmic ray bombardment of the earth’s upper atmosphere. In any event the facts strongly indicate that assumption 2 above is not completely valid. But possibly, too, there may have been in the past some major disturbance of the C-14 production and distribution system that invalidates assumption 3.
Is there evidence for a major disruption of C-14 production and distribution?
There is, indeed, striking evidence for disruption of the steady state conditions on which the C-14 method for dating fossils is based. Buried in the sedimentary rocks of the earth’s crust are vast deposits of the carbon-containing fossil fuels, coal and petroleum, plus other carbonaceous materials. There are also huge formations of limestone containing carbon that once was undoubtedly in the circulating carbon inventory. The carbon in the fossil fuel and limestone deposits is not now in the circulating inventory, but it was in the past. This must mean that the circulating carbon inventory was formerly much greater than it is at present.
Would this affect C-14 ages?
In the current creation model it is postulated that a major part of the sedimentary rocks was deposited at the time of the Flood of Noah, as were most of the fossil fuel deposits. Dr. Robert H. Brown of Geoscience Research Institute estimates that at the time of the Flood, earth’s circulating inventory easily could have been reduced by a factor of 1 to 127. If this happened, what are the consequences for C-14 ages? Simply this: With a circulating carbon inventory 127 times greater than at present, and assuming the current rate of C-14 production, the equilibrium C-14 concentration in living things prior to the Flood was 1/127th of the current value. This means that plants and animals that died and were buried and fossilized prior to or during the flood had only 1/127th as much C-14 in their carbon as do modern living organisms. Consequently, C-14 age estimates of such fossils would be too high by about 40,000 years! If, in addition, it is assumed that the earth’s pre-flood C-14 magnetic field was four times greater than at present (not an unreasonable possibility), the resulting deflection of cosmic rays would have reduced the pre-flood C-14 production rate to about half the present rate. This would add an additional half-life, or about 6,000 years, to the error in C-14 age estimates for fossils interred at the time of the Flood or before. Thus, a fossil produced by the Flood, which is considered to have taken place perhaps 5,000 or more years ago, would now have an apparent C-14 “age” of at least 40,000 + 6,000 + 5,000 = 51,000 years. This is at the upper limit for the method and thus represents essentially an infinite C-14 age. [Note: New, more sensitive measures of C-14 content have some promise of extending the range of this method.]
If all of the necessary facts were known quantitatively, that is, how much carbon was buried and how strong the pre-flood magnetic field was, a correction factor could be deduced to correct all C-14 “ages” to values in the range consonant with the Genesis record of creation and the global catastrophic Flood of Noah.
What about carbon-14? We do not know the exact facts required to correct C-14 “ages” precisely. However, it is certain that the C-14 dating method does not prove that the evolutionary scenario for earth history is valid. It appears that the pertinent data can be accommodated to a very much shorter chronology that fits the Genesis account.
— Creation Essay by Dr. Robert Kofahl, Ph.D