In contrast with the radiocarbon system of dating, the magnetism system was developed and refined solely by creationists because of its claim to limit the earth's age to ten thousand years. In fact, for the first decade of its existence noncreationist scientists never even took notice of Barnes's proposal. It wasn't until 1981 and 1982 when the creationist controversy erupted in the classrooms, when the Arkansas and Louisiana creationist legislation was being challenged in the courtrooms, and when scientific societies were beginning to have papers attacking creationism at their annual conventions that Barnes's ingenious method of dating the earth by its magnetism was brought to the attention of the scientific world. A comprehensive rebuttal of the magnetism-decay method of dating was recently published in the Journal of Geological Education by G. Brent Dalrymple, 2 who is employed by the U.S. Geological Survey as an expert in radioactive dating, especially the potassium-argon method. In reaction to Dalrymple's criticisms, Barnes has written a four-page response for the Institute of Creation Research's Impact series entitled "Earth's Magnetic Age: The Achilles Heel of Evolution," which begins with these words: "There is nothing more devastating to the doctrine of evolution than the scientific evidence of a young earth age. That evidence is provided by the rapid depletion of the energy in the earth's main magnet, its electromagnetic dipole magnet in the conductive core of the earth." 3
Creationists who believe in an old earth have also attacked Barnes's model because it limits the earth's age to a maximum of ten thousand years. For example, an associate professor of geology at Calvin College, Davis Young, has devoted a whole chapter in his latest book to pointing out the flaws in the magnetism method of determining the age of our planet. 4 As a result of Young's criticisms, Henry M. Morris, whose name is almost synonymous with creationism, wrote a pamphlet under the title Science, Scripture, and the Young Earth. 5 Three pages in this thirty-four-page work are devoted to rebutting Davis Young's critique of Thomas Barnes's model for the decay of the earth's magnetic field.
Because the controversy surrounding Barnes's geomagnetic age model has spilled over from the pages of creationist periodicals into the classroom, the court room, convention halls, and even into pulpits, it certainly behooves clergy and Christian laymen alike to be aware of its implications and to have the means whereby each can evaluate its validity from both a scriptural and a scientific standpoint.
Without becoming intricately involved in all the scientific ramifications, we can summarize what the model being proposed by Barnes is about. The earth can be compared to a gigantic magnet having two poles, which is why its magnetism is called dipolar. The two poles are oriented within the earth along the north-south axis of the earth's rotation. While the magnetic forces are very complex and are continually in a state of flux, we can clearly identify the main component of the total magnetic field, and it is called the dipole field. The other components, which are lumped under the nondipole field, comprise only a fraction of the total magnetic field. Barnes's theory is restricted solely to the dipole component.
The strength of the earth's dipole field can be described in terms of the geomagnetic moment. Precise measurements from various observatories have indicated that the magnetic dipole moment has been decreasing in intensity from 1835 to the present time. For understanding the magnetic record prior to 1835, scientists turn to geology and archeology and look for evidences of paleomagnetism in the earth's crust. The magnetic forces have left their imprint upon rocks, such as lava flows, and in loose sediments, such as lake beds and deep-sea sediments, and sensitive instruments can decipher what some of the magnetic forces were at the time the rocks and sediments were first deposited. One branch of paleomagnetism, called archeomagnetisrn, attempts to analyze the forces of the magnetic field as derived from archeological artifacts subjected to high temperatures, such as pottery and bricks from kilns. The imprint of the earth's magnetic field was left upon tiny slivers of magnetic minerals that were reoriented according to the lines of the earth's magnetism at the time the kilns were fired. The magnetic record then was "locked in" the ancient artifacts, allowing modern man to unlock through special instruments the intensity and direction of the earth's field in the past. The controversy centers upon the accuracy of these paleointensity measurements derived from rocks, sediments, and artifacts. Barnes contends that the only accurate measurement of the earth's dipole moment is through actual observatory measurements that are averaged on a worldwide basis.
The calculations for the earth's age using changes in the earth's magnetic moment are derived from thirty-four observatory measurements over a 150- year period starting in 1829. Such measurements of the earth's dipole moment can be graphed, showing the relationship between intensity and time (see figure 1). Equations can be developed for the continuous decrease In intensity, or "decay of the earth's magnetic field," as Barnes calls it. The graph can be extended backward in time. Assuming a more or less constant "decay rate," one can estimate what the intensity of the magnetic field was at any time in past history by means of extrapolation from present conditions. According to the equations used by Barnes, the strength of the earth's magnetic moment would have been fifty thousand times greater some twenty thousand years ago than what it presently is. Of course, this would be impossible because of the amount of heat energy generated through the flow of the associated electric currents--some 250 million times greater than today's values as estimated by Barnes. 6 With the presumed electrically generated heat twenty thousand years ago, according to Barnes, the entire earth would have been a molten liquid, and life could not have existed. Based upon a decaying magnetic field, Barnes feels that the earth could not be more than ten thousand years old, and more likely has an age of six thousand or seven thousand years, thus conforming with the Biblical record.
The magnetic decay method of age dating has been proclaimed as the most reliable evidence available for establishing a young age for the earth. As Henry Morris puts it, "If any process should be a reliable indicator of the earth's age, this should be--and it indicates an upper limit for the age of about ten thousand years!" 7 It merits therefore a close scrutiny by creationists first from a Biblical standpoint and second from a scientific one.
The Bible neither confirms nor denies the validity of age dating by the decay of the earth's magnetic field. However, some creationists feel that in general it addresses the question of whether physical processes are going from a high energy state to a lower energy state based upon the second law of thermodynamics. They feel that it is part of the curse placed upon the earth when man sinned (Gen. 3:17-19), thus becoming the reason why "the whole creation groaneth and travaileth in pain together until now" (Rom. 8:22). The "whole creation" would include the interior of the earth and the magnetic field that is generated from the earth's core. The fact that "the earth shall wax old like a garment" (Isa. 51:6) is thought to be another evidence of the inexorable law of decay affecting the physical world. Even the "foundation of the earth" its core is included in this aging process (Ps. 102:25, 26). Whether the second law of thermodynamics was indelibly inscribed on the fabric of nature because of man's sin, and whether this law mandates the decay of the earth's magnetic field, are essentially theological questions and therefore must be evaluated further by Biblical scholars.
Actually, the magnetic decay method of age dating must stand or fall upon its scientific evidence, even though there are scriptural implications as well. It is exhibit A among the various scientific evidences for a young earth--number one in a list of sixty-eight such evidences. 8 In spite of its seemingly impressive scientific credentials, it falls short of being a valid scientific method of dating because of at least four major weaknesses. (In my critiquing of this method of age dating please note that I am not criticizing the. Christian integrity and dedication of those who have promoted this view, nor am I departing from the theologically based creationist stance of MINISTRY magazine. The criticisms are from a creationist viewpoint.)
1. Magnetic age dating is mare rigidly uniformitarian than the principle of uniformitarianism as currently explicated by geologists. Uniformitarianism is the dogma that "the present is the key to the past"--that past conditions in earth history can be adequately understood in terms of present earth processes; When applied to radiometric age dating, geologists must assume that the rate of radioactive decay has been constant with respect to time. If it has not been, then all radiometric dates are spurious indicators of real time. Radioactive dating extrapolates backward in time on the basis of radioactive decay at a constant rate. However, the extrapolation is not done in the dark, because certain checkpoints are sought out that might be tied to the time scale being developed, and these are used to verify the accuracy of the method. The magnetic decay dating of Barnes looks for virtually no checkpoints prior to 1835; it ignores any possible evidence from archeomagnetism, paleomagnetism, geology, or historical records to test the validity of its extrapolation. It is based upon observations made solely in the past century and a half, which are then extended back ward into the unknown of the past. It is literally a "stab in the dark"--more rigorously uniformitarian than the age-dating methods used by geologists. Whether one accepts any validity for radiometric dating, one would have to recognize that each method of radiometric age dating must be calibrated with one or more other methods. The magnetic decay method has no such calibrations. It is a strictly theoretical extrapolation back into the past over a time range seventy-five times greater than the time range over which the magnetic measurements were made. Strange indeed is the fact that those who are most vocal in advocating this method, which is thoroughly uniformitarian in its logic, are the most outspoken in rejecting uniformitarianism as a means of understanding earth history!
2. Paleomagnetic measurements indicate that the earth's magnetic field several thousand years ago was the same as today's values, not drastically higher. Figure 2 portrays the global average for dipole intensity for the past ten thousand years based upon a 1982 study. 9 Obviously those who use the magnetic decay method of dating must disavow any connection between recent dipole intensity measurements and the paleomagnetic record. For example, Barnes states: "Over the last two centuries the work of Gauss et al. has shown a continuous depletion of the earth's magnetic field. That is generally accepted as fact, whereas the magnetized rock-artifact method fails to show any trace of this trend." 10 Such a statement is simply erroneous. Figure 2 demonstrates that for the past eight hundred years the paleomagrietic record depicts a sharp decrease in magnetic intensity, averaging 3.3 percent per century. The data based upon more accurate observatory methods of calculation indicates a corresponding decline of 4.6 percent per century since 1835. In light of the fact that bricks and pottery burned in kilns do not register the magnetic intensity as accurately as very sensitive laboratory instruments would, we are surprised to find a correlation so remarkably close. In fact, paleointensity measurements from archeological sites in Poland and the Ukraine spanning the past 750 years depict an average decrease in intensity of 4.7 percent per century--essentially no different from recent observatory data. 11 I have examined a half-dozen paleomagnetic studies of ocean and lake sediments, and in each case I have found a sizable constant decrease in paleointensity during the past several centuries.
Having established a fairly good link between observatory measurements and paleointensity data over the past few hundred years, we can be confident that the paleointensity data for the past several thousand years does give useful approximations for the earth's dipole moment in the past. Again examining figure 2, we find that on occasion the earth's paleointensity was the same as or even lower than today's values. This of itself is sufficient to invalidate the use of the earth's magnetic decay for dating purposes.
The magnetic decay dating method ignores what I have called the "roller coaster effect" upon the earth's dipole moment. Over a short term it may indeed appear that the magnetic field has been rapidly decaying, but over the long term we find rapid increases in intensity to counterbalance the sharp decreases. To use a method of extrapolation for dating purposes is no different than a nearsighted man who attempts to judge the original height of the roller coaster track at its start by examining the last hundred feet of the track only. If he finds a fifty-foot drop in the last hundred feet, and if he is told by the operators that the total length of the track is one thousand feet, then he calculates that the track must be five hundred feet high at its start! Likewise, to assert without observational data that the intensity of the earth's magnetic field must have been fifty thousand times greater some twenty thousand years ago is to ignore this crucial "roller coaster effect" upon the fluctuating magnetic field.
3. The magnetic decay method of age dating is inconsistent in its use of radiocarbon data. One outcome of the development of this method was that it offers an easy explanation as to how radiocarbon dates in the range of ten thousand to forty thousand radiocarbon years can be easily compressed to a span of fewer than ten thousand solar years. This is based upon the fact that there is an observable direct correlation between the intensity of the earth's magnetic field and the production of radiocarbon in the earth's upper atmosphere. Radioactive carbon atoms are produced when cosmic rays bombard the atmosphere, but the magnetic field acts as a shield to block the entry of cosmic rays. When the strength of the magnetic field increases, the production of radiocarbon decreases, and the radiocarbon time scale is altered. Radiocarbon ages then become older with respect to real time. Whereas if the magnetic field strength were to decrease, the opposite would be the case. Barnes suggests that the effects of cosmic ray intensity in producing radiocarbon were lowered by some 10 percent about 2,800 years ago when the earth's magnetic field was said to be four times stronger than today. u Radiocarbon ages going back to 800 or 900 B.C. then should be a few hundred years older than calendar ages.
Using the science of dendrochronology (tree-ring dating) as it has been applied to bristlecone pines of the American Southwest and the oaks in Northern Ireland and Germany, we can deduce the level of radiocarbon production at any particular century in the past five thousand years or so. A master tree-ring chronology is composed of hundreds of trees forming overlapping tree-ring sequences. This gives an age for any tree in the sequence. Certain trees in the sequence are then dated by radio carbon dating, and the radiocarbon age is compared with the dendrochronological age. If the intensity of the earth's magnetic field were many times higher five thousand years ago, the radiocarbon age should be hundreds if not thousands of years higher than the dendrochronological age, providing the dendrochronological age is equal to the calendar age. But the very opposite is the case; the radiocarbon age is consistently lower by several hundred years than the tree-ring age. This indicates that the earth's dipole moment in 3000 B.C. was actually weaker than today's values. It is interesting that the magnetic decay method of dating, which is supposed to offer a ready explanation as to how radiocarbon dates have become greatly expanded beyond real time, is now being challenged by the radiocarbon dating of tree rings.
The only way out of this dilemma is to deny the validity of dendrochronology, but in doing so one would have to proceed one step further and deny the validity of Egyptian chronology. That's because radiocarbon dating of Egyptian artifacts that have been dated historically yields radiocarbon ages that appear several hundred years too young, just as the dating of tree rings from the same period also yields radiocarbon ages several hundred years too young. An attempt to revise drastically Egyptian chronology for the first two millennia B.C. has repercussions on Biblical chronology that is linked with the Egyptian at certain points. The safest course is to allow the synchronisms between Egyptian and Biblical chronology to remain intact, thus calling into question the whole magnetic decay method of age dating.
4. The equation developed for predicting past intensities of the earth's magnetic field is entirely arbitrary. Basically there are two types of equations that can be used--exponential and linear. An exponential equation would describe a curved line when plotted on a graph with uniform scales, while a linear equation would give a straight line. The choice of an exponential equation is purely arbitrary and is based upon theoretical assumptions about how the earth's magnetic field ought to behave in the inner core of the earth, as stated in the following words: "One would expect the magnetic moment of the earth to decay exponentially because it is produced by real currents that dissipate energy through joule heating." 13 The existence of real currents dissipating energy within the earth's core is an assumption, and very little is known at present about the processes occurring within the core.
Observational data of the earth's magnetic dipole from 1829 to the present would suggest a linear decay process to be just as valid. Figure 1 has three data points marked "E." These points do not represent observational measurements, Figure 2 but rather they are estimates derived from the exponential equation developed by Barnes to calculate the earth's magnetic intensity. When one has only 150 years of observatory measurements, one finds it impossible to tell whether the decay should be linear or exponential.
(The dashed line in Figure 1 is linear.) However, there's a vast difference in results, depending upon which equation is adopted. Extrapolated backwards in time, an exponential equation would yield vastly higher paleointensity values ten thousand years ago than a linear equation would. For example, the paleointensity derived from the exponential equation at ten thousand years ago would be equal to the paleointensity derived from a linear equation extending back 120,000 years! Of course, we have already referred to the fact that such extrapolations are more intensely uniformitarian than the type of uniformitarianism practiced by scientists today. Any type of extrapolation needs check points. A recently published study gives the scant magnetic intensity data from the 16th century. According to Figure 3, such data provides greater support to a linear extrapolation of 19th- and 20thcentury data, than it does to an exponential one. 14
In summary, even though the magnetic decay method of providing upper limits on the age of the earth looks intriguing on the surface, it is riddled with problems and major inconsistencies. It is based upon uniformitarian logic, even though ostensibly it would reject uniformitarianism as a valid method of scientific research. It ignores paleomagnetic and archeomagnetic data covering the past several thousand years, even though such data over the past few hundred years is conformable with magnetic decay theory and observations. It is championed as a convenient way out of the problems to a short chronology that are caused by radiocarbon dating, although it fails to realize that the radiocarbon evidence over the past five thousand years would negate magnetic decay theory. And finally it arbitrarily uses an exponential decay relationship when a linear relationship is just as compatible with observatory data. The cause of creationism is not served very well by a speculative theory that is fraught with so many internal inconsistencies, and it is time for the theory to be taken back to the drawing board before it is launched again.
