The Creation Explanation
|The Age of the Earth|
The discussion thus far has dealt with radiometric clocks which have long half-lives and should be appropriate for obtaining ages for objects having ages from, say, one-tenth to several times their half-lives. However, what radiometric "clock" can be used to date objects from King Tut's tomb or from an ancient Inca temple? Dr. Willard Libby of the University of California at Los Angeles first suggested that carbon-14, which is formed in an distributed throughout our atmosphere and thus exists in all plants and animals, could be used to date objects of any age from recent times to about 40,000 years ago.
The discovery of this method was an important contribution to the study of ancient civilization(archaeology) and also to the study of ancient plant and animal fossils(paleontology). Events in fairly recent earth history of interest to geologists have been dated by this method. One example would be the dating of trees buried in a recent glacier.
As in the case of all other radiometric dating methods, the carbon-14 method is based upon a combination of reproducible scientific data and certain assumptions about events and processes in the ancient past. Here are the basic elements of the method:
1. Ordinary carbon atoms have nuclei composed of six positively charged protons and six neutrons having no electrical charge. The mass of a proton is about equal to that of a neutron, about one atomic mass unit (1 AMU). Thus an ordinary carbon atom can be represented by the symbol 12C6, where the subscript tells the number of protons in the nucleus, and the superscript tells the mass of the atom in AMUs. We will sometimes write this kind of carbon as carbon-12, or C-12. All carbon atoms have six protons, but some have different number of neutrons in their nuclei. These are different isotopes of the element carbon.
One isotope of carbon is carbon-14, which has six protons and eight neutrons. Its symbol is 14C6. Carbon-14 atoms are continually being produced in the upper atmosphere as a result of cosmic radiation from outer space. Cosmic radiation consists of atomic nuclei which are traveling at extremely high velocities approaching the speed of light. They therefore carry extremely large kinetic energy. When these particles smash into atoms in the upper atmosphere, the collisions disintegrate atomic nuclei and produce showers of various atomic particles. Among this atomic debris are many neutrons. When one of these neutrons has the proper velocity collides with a nitrogen-14 atom in the atmosphere, a nuclear reaction sometimes takes place.
Nitrogen (symbol 14N7) , which comprises about 78 percent by volume of the atmosphere, has seven protons and seven neutrons in the nuclei of its atoms. When a neutron reacts with a nitrogen-14 nucleus, it knocks a proton out of the nucleus and replaces it. The result is an atomic nucleus containing six protons and eight neutrons. Thus the atom has been transmuted from nitrogen-14 to carbon-14. This nuclear reaction can be represented as follows:
1n0 + 14N7 14C6 + 1p1
The symbol for the neutron, 1n0, means that its mass is 1 AMU and its charge zero. The symbol for the proton, 1p1, means that its mass is 1 AMU and its charge is +. About 10,000 grams (22 lbs) of carbon-14 are being produced annually by this reaction.
Ordinary carbon, carbon-12, is stable, but carbon-14 is unstable, decomposing radioactively with a half-life of about 5,730 years. The radioactive decay reaction is
14C6 14N7 + b-
2. This carbon-14 combines with oxygen to form carbon dioxide gas which diffuses down to mix with all the atmosphere.
3. Plants use carbon dioxide in their life cycles and become radioactive. Animals and people eat plants and become radioactive. Ordinarily C-12 from living things contains about 1.18 atoms of C-14 to every trillion atoms of C-12. This means that if we placed one gram of ordinary carbon from a living thing under a Geiger counter, we would observe about 816 counts(caused by beta particles from C-14 disintegrations) per hour. After the organism died, this count would decrease according to the curve in figure 8-3. The C-14 change back to N-14 with a half-life of 5,730 years.
4. When an organism dies it stops taking on more radioactive carbon-14, so the amount in the dead object begins from the moment of death to decrease at a rate which reduces the amount by a factor of one-half each 5,730 years, the half-life of carbon-14.
5. Thus, if we obtained some charcoal from an ancient Cro-Magnon campfire in France and found that one gram of purified carbon yielded a count 204 counts per hour, we would conclude that the date of campfire was about 11,460 years before the present, if the assumptions underlying the method are valid.
Most of the radio-carbon dates deter; for objects of known historical age back to about 1500 B.C. agree with their historical ages reasonably well. For instance, the Dead Sea Scrolls were found to yield a C-14 date of about 2,000 years before the present. However, this is not true of all objects of interest to geologists and paleontologists. Table 8-3 lists some of the discrepancies.50
table 8-3. Some Sample Carbon-14 Age Estimates
Carbon-14 dating requires assumptions.
For the method to be valid as a direct indicator of real time, the concentration of carbon-14 in the carbon of living organisms must have attained an equilibrium value in the biosphere and remained constant over the entire time period of interest. It must be assumed, then, that for a time of the order of 50,000 to 100,000 years the following factors have been essentially constant:
1. The rate of cosmic ray bombardment of the upper atmosphere and thus the resulting rate of production of neutrons.
2. The concentration in the upper atmosphere of water molecules(which absorb neutrons).
3. the amount of carbon-12 in the circulating carbon inventory from which living things derive their carbon, and into which the annual production of carbon-14 is dispersed.
Each of the above factors affects the concentration of carbon-14 atoms dispersed in the carbon-12 atoms of the circulating carbon inventory from which the bodies of living things obtain their carbon content. If any of these factors have, in periods in the past, been different from their modern values, the carbon-14 ages of organisms which died in those periods will not be real-time ages. If the extent of past deviations of these factors from present values could be determined, it might be possible to develop conversion factors to convert carbon-14 ages into real-time ages.
Can Carbon-14 Ages Be Corrected to Correlate them with a Biblical Chronology?
It is a fact that fossil organic remains yield carbon-14 ages up to and exceeding 50,000 years. On the other hand, the early chapters of Genesis provide valid historical data that planet Earth has supported life for around 10,000 years. Those who accept a straightforward grammatical-historical interpretation of Genesis 1-11 and yet do not ignore pertinent scientific data, have an obligation to seek a reasonable interpretation of carbon-14 age data that is different from the most direct interpretation based on laboratory data and the standard assumptions which have been discussed above. Their situation is comparable with that of an attempted reconstruction of an automobile accident, or a singular event of nature, based on eyewitness and after-the-event physical data, compared with an attempted reconstruction based only on after-the-event physical data. We are indebted to Dr. Robert H. Brown of Geoscience Research Institute, who has carefully analyzed the options open to those who wish to correlate a short chronology for the history of life on the earth with carbon-14 age estimates.51 Organized under three factors listed earlier, his conclusions are as follows:
1. There are two possible causes for substantial variation in cosmic ray flux at the top of the atmosphere: variations in the cosmic ray intensity in our galaxy, and variations in the geomagnetic field intensity. In the first instance, evidence from radioisotopes in meteorites indicates that the galactic cosmic ray intensity has not varied by more than a factor of two. This could produce errors in carbon-14 age estimates by only one half-life, or 5730 years. The geomagnetic field deflects cosmic rays from the earth, allowing only a portion to reach the atmosphere. And increase by a factor of 11 could have reduced the cosmic ray flux by a factor of four. this, however, could produce an error in carbon-14 age estimates of no more than two half-lives, or about 11,500 years. There is no evidence that the geomagnetic field intensity has ever been eleven times greater than at present. The actual evidence indicates that over the period for which there are reliable historical records the geomagnetic field intensity has never been greater than twice its present value. It is not unreasonable to presume that in the ancient past the geomagnetic field intensity could have been up to four times greater.
Dr. Brown points out that comparison of carbon-14 ages of growth ring wood from ancient trees in the White Mountains of eastern California with the ages from growth ring counts shows that carbon-14 ages for time earlier than 1500 B.C. become increasingly lower than the tree ring ages. The errors are as large as about 650 years. This suggests that there was a period a few thousand years ago in which cosmic ray interaction with the atmosphere was greater than at present, leading to up to nearly eight percent higher concentration of carbon-14 in the living organisms of that era. Eight percent would correspond to 650 years of radiocarbon time.
It can be seen, then, that variations in cosmic ray interaction could be responsible for some difference between carbon-14 ages and real-time ages, but it is not likely such variations could combine to produce more than one or two carbon-14 half-lives of difference, 6,000 to 12,000 years.
The conclusions we have drawn here rest on the assumption that the tree ring counts give actual historical ages of the wood in the rings. There are some sources of error in tree ring chronologies that raise some question about the accuracy. In some years no ring is formed, while in others two may be formed. In addition, the computerized overlapping of the ring counts of successive dead trees may not be entirely reliable. However, Dr. Gerald Aardsma of the Institute for Creation Research has published the results of an exhaustive statistical analysis of the published tree ring chronology.52 He concludes on the basis of consistent statistical evidence that the published tree ring chronologies are reliable. If this is so, then the divergence of the carbon-14 ages from the tree ring chronology supports the view that a fundamental assumption necessary for the validity of carbon-14 ages is in fact itself invalid. The concentration of carbon-14 in the circulating carbon inventory has not been constant for 50,000 years. Other types of information corroborate this conclusion. There are several possible causes of this variation.
2. The present concentration of water molecules in the upper atmosphere is now typically less than five per million molecules of nitrogen and oxygen. Thus very few cosmic-ray-generated neutrons are captured by water molecules, and 96 percent are captured by nitrogen-14 atoms to produce carbon-14 atoms. If the ancient stratosphere contained six times as many water molecules as oxygen and nitrogen molecules combined, only 40 percent of the neutrons would react with nitrogen atoms to produce carbon-14. The difference from 40 to 96 percent production amounts to 96/40 = 2.4 = 21.26 fold difference in carbon-14 production. The 1.26 half-lives is only 7200 years. There is no established mechanism which could have maintained such high concentration of water in the atmosphere.53 Thus it seems highly unlikely that stratospheric water could be an appreciable factor in causing significant differences between carbon-14 ages and real-time ages.
3. The third factor that is a possible cause of substantial difference between carbon-14 age and real-time age is variation in the circulating carbon inventory from which the carbon in living things is derived. The estimate of the total carbon in living and dead organisms, in the atmosphere, oceans, and water near the land surfaces very complex and subject to many possible errors. The same may be said for the estimates of the total carbon in coal, oil and other organic deposits and in sedimentary carbonate deposits. However, if it be assumed that this buried carbon was once a part of the circulating biosphere carbon inventory, it can be seen that there has, indeed, been at some time in the past a very large decrease in the size of the circulating inventory of carbon in the biosphere.
Dr. Brown's calculations indicate that if one-third of the combined known coal, oil and other organic deposits and only 20 percent of the sedimentary carbonates were deposited in geological formations by a global catastrophe, the size of the circulating biosphere carbon inventory would be reduced by a ratio of 1/127. This would mean that before this event, the cosmic-ray-produced carbon-14 was dispersed in 127 times as much circulating carbon inventory. Consequently, once equilibrium had been reestablished after the catastrophic event, the concentration of carbon-14 in living things as was 127 times larger than it was before the event. This corresponds to 40,000 years in carbon-14 age. If it is also assumed that the geomagnetic field strength before the global catastrophe was about four times the present value, the rate of production of carbon-14 was reduced to about one-half the present rate, reducing the carbon-14 concentration in the pre-catastrophe atmosphere by another factor of one-half. This corresponds to one half-life or about 6,000 years. Thus a fossil (buried before or during the global catastrophe) which today yields a carbon-14 age of 53,000 years would actually be only 7,000 years old (53,000 - 40,000 - 6,000).
Is Carbon-14 In Balance?
If the tree ring studies referred to earlier in this chapter provide a chronology that accurately represent real time, the carbon-14 content of the older rings indicates that less than 10,000 years ago the carbon-14 in the biosphere was not in balance with the annual production. For some unknown period the rate of production would have been greater than at present, making the biosphere carbon-14 at least eight percent greater than the present value.54 This means that carbon-14 equilibrium between all parts of the circulating carbon reservoir has not existed over the past 10,000 years, although the close agreement between carbon-14 age and real-time age over the past 3500 years indicates that probably the concentration of carbon-14 in the earth's atmosphere and surface waters had been approximately constant for the last 3000 to 4000 years. Due to decay of carbon-14 to nitrogen-14 during the transition time for transport of carbon-14 from the atmosphere to the various levels of the ocean the surface layers of the ocean are about 5% deficient and the deep ocean averages about 16% deficient in carbon-14 with respect to the atmosphere.55 Dr. Brown estimates that the deep oceanic carbon may now be at about 91% of the carbon-14 concentration it would ultimately attain at the present rates of production and mixing of carbon-14. If these rates were to be maintained the ocean should be at 97% of its ultimate carbon-14 content about 9000 years from now.
Thus not only is there evidence that carbon-14 production has not been in equilibrium with carbon-14 in the circulating carbon inventory at times in the past, but dynamic equilibrium of carbon-14 in the deep oceans has not been attained. Why is this so? The traditional views of geology and earth history allow millions of years for carbon-14 equilibrium to become established. There are two possible causes for lack of equilibrium in this system: 1) The system has not been in existence long enough to attain equilibrium, or 2) The system has been upset at some point not too far in the past. Both of these possibilities accord with the young-earth creation-flood model.
Creationist literature contains several carbon-14 models based on the assumption that carbon-14 in the biosphere is increasing toward the equilibrium value.56 As we have seen, however, a simple model is not sufficient. Furthermore, if a present degree of deficiency from equilibrium exists, it is apparently less than earlier estimates indicated. Equilibrium estimates must be based on a uniform continuation of processes and rates as presently estimated. The inadequacy of such an approach for harmonization of carbon-14 data with a short earth chronology becomes readily apparent from the realization that at the rate carbon-14 is presently produced in the atmosphere, the total accumulation of carbon-14 during the past 5000 years would be only about 31,000 kilograms. This is the time many creationists assume since a global, catastrophic burial of much of the earth's early circulating carbon inventory. But 31,000 kg would be no more than 70 percent, and most probably only about 45 percent of the present world inventory of carbon-14. And note that fossils from organisms buried in that catastrophe, in accord with Dr. Brown's model, would not contain carbon-14 measurable by currently established techniques.
Models In Competition
The traditional evolutionary carbon-14 model postulates almost unlimited time for the global carbon-14 production and distribution system to function, with essential equilibrium for a very long time, but with occasional events which have disturbed the system. On the other hand, most creationist carbon-14 models postulate a much more limited time for the system to exist, with at least one global catastrophe(a flood) which displaced the system extremely far from equilibrium. In the model proposed by Robert Brown it is postulated that the geomagnetic field strength was about four times the present value. It is further postulated that the circulating carbon inventory was reduced by a factor of about 127 by two effects: 1) the burial of about one-third of the present known fossil carbon deposits, and 2) the deposition of about one-fifth of the present carbonate sediments. The reduction of the carbon inventory by a factor or 127 resulted in the eventual increase in carbon-14 concentration in living organisms in the post-flood era by a like factor. The factor 127 equals 26.99, corresponding thus to 6.99 carbon-14 half-lives, or about 40,000 years. Thus carbon-14 ages for biological specimens which died before or during the global catastrophe are greater than their true historical ages by about 40,000 years. An additional postulate of this model has been mentioned earlier, i.e., a temporary increase in the rate of carbon-14 production. This model collapses the carbon-14 chronology to a range which accords with the young-earth creation model. The three effects and their resulting shortening of the carbon-14 chronology are displayed in Table 8-4. The values given in this table are only suggestive as to how a modeling compatible with a short earth chronology might be conducted.
table 8-4. Tentative Model for a Carbon-14 Young Earth Chronology
Figure 8-5. Speculative Model for C-14 Production and Relative Concentration Trends Associated with the Flood.51 Vertical scales are arbitrary and have no quantitative significance. Horizontal scale is solar years before (B.F.) and after (A.F.) the flood. Lines are drawn to indicate hypothetical changes only in trend, not magnitude. Total carbon is that in the atmosphere, fresh water, ocean surface, organisms, and undecomposed organic material. The lines are intended to give a suggested first-order approximation that conforms to the chronological data in the Masoretic text data, and the excess of total C-14 inventory over expected accumlation in 5000 years at 8.92 kg/yr.
In Robert Brown's model portrayed in figure 8.5 the global catastrophe, taken to be the flood of Noah, is assumed to have buried much of the earth's circulating carbon inventory. Prior to the flood, the much larger circulating carbon inventory in which the annual production of carbon-14 was absorbed and mixed kept the concentration of carbon-14 in the biosphere at a level considerably lower than it is today. After the flood, for undetermined reasons, the rate of production of carbon-14 increased rapidly to a value somewhat greater than the present rate, then decreased to the present value. After the flood, the concentration of carbon-14 in the atmosphere increased, primarily because of the much smaller circulating carbon inventory.
If the above scenario is correct, what would be the effect on carbon-14 age estimates for fossil materials? First, since the circulating carbon inventory was much larger before the flood than after, the concentration of carbon-14 in living organisms was smaller before the flood than after. The carbon-14 method in the hands of secular scientists includes the assumption that this concentration has been constant for, say, 100,000 years. Therefore, their use of the carbon-14 method on fossil plants and animals which lived and died prior to the flood or during the flood will yield excessively high ages.
On the other hand, the fact that the bristlecone tree ring chronology shows that carbon-14 ages for a time after the flood are up to 8 percent low suggests that in the immediate post-flood period there was a temporary disturbance that increased the production of carbon-14 for a limited time. Once the disturbance in the system ceased, the excess carbon-14 would have leveled off to the normal production rate. This effect is portrayed in figure 8-5.
Dr. Brown has also surveyed carbon-14 data which supply supporting evidence for an increase in carbon-14 concentration in the biosphere in the post-flood era. For example, different parts of some significant individual fossils have yielded discordant ages that are suggestive of increasing carbon-14 in the biosphere, as shown in table 8-5.
table 8-5. Anomalous Carbon-14 Ages of Individual fossils.57
Robert Brown has published a statistical analysis of the carbon-14 ages of peat bog and cave deposits versus depth in the deposits.58 He found a predominant universal trend for sediment, soil, and peat profiles. They have a larger carbon-14 age interval per centimeter of thickness as relative depth and the carbon-14 age increase. This trend is greater than can be accounted for satisfactorily by gravitational compaction, and it is consistent either with less rapid erosion, sedimentation, and peat growth or with a decreasing concentration of carbon-14 as one goes farther into the ancient past. Large, systematic inconsistencies in carbon-14 "ages" of a frozen Alaskan musk ox and of accumulated dung pellets left in Rampart Cave by ground sloths support this conclusion that the concentration of C-14 in the atmosphere was much less in the distant past.
In 1992 Dr. Brown took all of his previous studies into account to arrive at a conversion curve for correcting C-14 ages to real time. Figure 8-6 displays this curve which collapses C-14 ages up to 42,780 years down to 5350 years of real time.
figure 8-6. Plot of real-time (T) vs. radiocarbon time (R).59
It may be said that, although we lack much information about conditions and events in the past history of the earth, the above tentative model for correcting carbon-14 ages is both scientifically sound and consistent with a biblical chronology. The assumptions adopted for this model are reasonable, and the available data from radiocarbon literature provide considerable support for this interpretation of carbon-14 measurements. It can be hoped that future improvement of this model and more confirming evidence will provide us with a reliable procedure for converting radiocarbon ages to a time scale that conforms to a biblical a young earth chronology.
It should be mentioned that Dr. Brown's excellent work on the carbon-14 chronology is aimed only at providing a chronology for the human race which is in harmony with the biblical chronology. Unfortunately (from our perspective), Dr. Brown accepts and vigorously defends the standard secular chronology for the universe and an age of 4.6 billion years for the earth.
50. These samples, selected as representative of anomalies from the more than 15,000 radiocarbon dates published in Radiocarbon and Science, were reproduced in Boardman, William W., Jr., et al., Science and Creation (Creation-Science Research Center, San Diego, 1973), p. 176.
51. Brown, Robert H., Origins, Vol. 6, 1979, No. 1, pp. 30-44; updated in unpublished paper, "Interpretation of Carbon-14 Data," June 1982. We are greatful to Dr. Brown for permission to use this important material and for further updated information and editorial suggestions provided in July, 1984.
52. Aardsma, Gerald E., "Tree-Ring Dating and Multiple Ring Growth Per Year," Creation Research Society Quarterly, Vol. 29, March 1993, pp. 184-189.
53. Kofahl, Robert E., Creation Research Society Quarterly, Vol. 13, March 1977, pp. 202-206; Morton, Glenn R., ibid., Vol. 16, Dec. 1979, pp. 164-169.
54. Renfrew, Colin, Scientific American, Vol. 225, Oct. 1971, pp. 63-72; Ralph, E.K, et al., MASCA Newsletter, Vol. 9, No. 1 (Allied Science Center for Archaeology, Univ. Museum, Univ. of Pennsylvania, Philadelphia, 1973).
55. Siegenthaler, Ulrich, et al., Radiocarbon, Vol. 22, 1980, pp. 177-191.
56. Cook, Melvin, Prehistory and Earth Models (Max Parrish, London, 1966), pp. 1-10; Whitelaw, R.L., Creation Research Society Quarterly, Vol. 7, June 1970, pp. 56-71, 83.
57. Radiocarbon, Vol. 8, pp. 320, 321; ibid., Vol. 12, p. 203; ibid., Vol. 8, pp. 172, 173; ibid., Vol. 10, p. 216.
58. Brown, Robert H., unpublished paper cited in ref. 51.
59. _________, Creation Research Soc. Quarterly, Vol. 29, June 1992, pp. 45-47.