Constructing a Time Framework for Past Events
A NOTE ON AGE DETERMINATION AND ANCIENT HUMAN HISTORY.
Under existing technology, chemically derived dates of the truly ancient geologic past are more likely to be reliable than those of recent events, such as the rise of Man. Exceptions to this rule include the age of the earth itself, and of other celestial bodies; and that portion of human history covering roughly 2,500BC to present, where there is incontestable calibration against human artifacts. There are very strong arguments for increasing the 2,500BC limit to 10,000BC or more, chiefly on the basis of calibration against tree-rings. Further exceptions to this rule are possible and advancing technology may dramatically change this chemical dating scenario at any time.
Dating of celestial objects often involves different methods to those employed in dating objects on the earth. The proposed age of Earth itself is such a case. Since no-one can seriously argue that they have a piece of the very first substance formed as part of this planet, standard radiometric dating of earth rock cannot fix our planet's origin date.
The four thousand, six hundred million-odd years attributed to the earth is the radiometric date of meteorites. Since the meteorites that have been dated cannot be proved to have formed at the same time as Earth, this does not establish our planet's age. However, in the case of celestial bodies, we may turn to other methods. The sun may reasonably be assumed to have been consuming itself at a somewhat steady rate, giving it an age of four to five thousand million years. It may be reasonably argued that the sun, some meteorites, and the earth have been in association for considerable time. The age of the meteorites fits this supposition. At least one other indicator also fits our proposed age. This indicator is the estimated ratio of elements making up the earth. Elements that radioactively decay become more and more depleted as time passes. Elements are not being new-formed on the earth. Manufacture of elements requires the pressure of collapsing stars. Elements that radioactively decay have been steadily depleting in the earth. Therefore calculations of the estimated bulk chemistry of the earth can give some guidance as to its likely formation date. These calculations are not inconsistent with the proposed age of the sun and of the meteorite samples. And the earth and the solar system themselves do have an appearance of extreme antiquity, not inconsistent with the ages proposed.
Were it not for this corroboration from a variety of sources, old-age radiometric dating techniques would rightly be regarded with skepticism.
It is common knowledge that radiometric dating relies on the decay of parent material, giving rise to daughter material, and thus, via measurement of the rate of decay (half life), to a "clock". Often, the parent and daughter are different elements, made different through radioactive decay. In some instances the parent and daughter are the same element, but are different, radioactive isotopes or atom-variants of it. Perhaps the greatest challenge to these methods has been the problem of contamination. When a rock is strongly heated or perhaps melted, the "slate is wiped clean". Elements recombine in new sites and settings within the rock. There is a new beginning, a new opportunity for accumulation of new daughter. Notwithstanding this clearing effect, parent and daughter can migrate within some minerals under some circumstances. Clean, "tight" samples therefore are a priority.
Irrespective of such potential inaccuracies, it cannot reasonably be denied that radioactivity points to an old earth. Probably the only way to disprove an old earth would be to show that radioactive decay is not constant over time, but is subject to deviations from modern observed rates of decay. The story of the past four thousand million years of the earth gives no comfort to this notion. Ancient chemical compounds formed according to the same principles of chemistry as modern substances. Yet it is equally true that our knowledge of chemistry is so embryonic, and the pool of potential knowledge so vast, that the tantalizing possibility of some sort of radioactivity revolution cannot be entirely dismissed from the radar. This is the dawning of the quantum age. The real forces and processes driving chemical reactions are being glimpsed. Novel states of matter are being discovered. Today's challenges in the nuclear industry could yet become tomorrow's successes?
Returning to the accuracy of radiometric dating: it will be understood that a clean, "tight" sample, and sufficient time for accumulation of an accurately measurable quantity of daughter, are essentials. The old earth calls for slow decay elements. More recent events call for faster decay elements. Elements useful for ancient events may be unsuited to more recent dating, and vice-versa. And, especially in the case of geologically insignificant time such as that of Man, both clean, "tight", recently heated rock specimens, and suitable fast-decay elements, may not always be available.
The old earth's call for slow decay elements is answered. The Uranium to Lead Decay Series is eminently useful for ancient rocks. Rubidium to Strontium and Potassium to Argon are examples of methods complementary to Uranium-Lead; Potassium-Argon especially is suited to medium-age and perhaps even younger samples. There is workable coverage of almost all of geologic history. The applicability and accuracy of such "workhorse" radiometric dating techniques tends to drop as we approach recent times.
As we have deduced, chemical dating of human history is a different matter to that of the dating of aeons of geologic time. Radiometric dates are not regarded as irrefutable unless the method can be cross-checked or calibrated in some way. There is inherent uncertainty. In the case of the old earth and its strata, we have, if not calibration, then at least a form of corroboration - the dates fit the age of the sun, the chemistry of the earth, and the story of the solar system. At the other extreme - documented human history - we have forensic examination of the sample, backed by calibrated Carbon14, or perhaps some less popular methods. Carbon14, after being thoroughly tested against artifacts of known age, and adjusted, can presumably give reliable dates, only back as far as it can be tested. Once correctly adjusted for part of its time-coverage, it does not automatically adjust for all of its coverage. It is somewhat different to the methods used to build a time- frame for the geologic history of the earth.
Historically there have been several chemical dating methods which have been applied to human history. C14 has been and probably is the most widely utilized. Potassium-Argon is sometimes employed, even for the short time-span of human history. Uranium Isotope (not to be confused with Uranium-Lead) shows promise: it relies on decay of one isotope of Uranium to another. Uranium is a component of minerals such as occur in teeth, shells, and coral. This method, and several others broadly of the same category, find use if circumstances are suited to them. A range of newer, quantum-age techniques are being developed. These are not radioactive decay methods as such but are a broad range of techniques purporting to discover an object's age by analyzing the amount of sub-atomic disturbance remaining from past events. Luminescence techniques, and Electron Spin Resonance, are included here. They seek to determine age by measuring the residual effects of natural radiation of all relevant types - e.g., radioactive particles, cosmic rays, even sunlight - on the sample. Natural radiation has something of a cumulative effect upon the behaviour of subatomic particles in, say, a bone or pottery sample, thus perhaps giving an indication of the time-span over which the object existed. Such innovative lines of enquiry may yet be a key to building a time framework for archaeology.
Methods such as these certainly have potential. In all cases accurate calibration is essential, and is sought. C14 is widely regarded as authoritative above most if not all other methods because it has been at least partly calibrated, is relatively easy to apply, and samples containing carbon are easy to find. It potentially can date specimens 40 or more(?) thousand years old. Can we be certain of its reliability, for dates prior to approximately 2,500BC - the limit set by the oldest C14-testable (organic) artifacts of certified age, from ancient Egypt?
Carbon14 is a radioactive isotope (atom variant) of carbon. A secondary effect of cosmic radiation penetrating the earth's atmosphere is the triggering of nitrogen14 to carbon 14 conversion. Like all chemical reactions, this conversion is an equilibrium seeking process. While events set in train by a cosmic ray are changing N14 to C14, C14 itself is naturally reverting to N14. A balance or equilibrium is reached when the rate of production of C14 equals its rate of decay. Equilibrium can only exist if factors such as atmospheric carbon content and cosmic radiation intensity are constant. They need to remain constant for 30,000 years for equilibrium to be attained. Thus, a date of 40,000years - which some laboratories say is at the limit of their measuring capacity - implies an atmosphere stable in terms of carbon content and cosmic ray intensity, for the last 70,000 years. If C14 production was not in equilibrium for all that period of time, then the "clock" is thrown. This timepiece assumes that carbon isotope ratios in the atmosphere, as measured during the 1950's, were constant back in time. When the organism in question died, it ceased carbon interchange with the atmosphere, and the relative proportion of C14 in its remains steadily declined through radioactive decay. Theoretically, it is a beautiful dating method. At very least, it has the potential to tell us something about the earth's atmosphere, even if it can be argued that its results prior to 2,500BC call for circumspection.
Arguments that have been directed against this method include: 1). When calibrating C14 against samples of known age, substantial adjustments, of the order of hundreds of years, were needed. The method itself was not questioned. Arbitrary adjustment is a feature of radiometric dating. 2). The atmospheric measurements taken in the 1950's (prior to extensive atmospheric nuclear testing and major recent industrial carbon output) suggested C14 production exceeding its rate of decay perhaps by 15-20%. If this measurement has any meaning, it can scarcely be that atmospheric C14 production is in equilibrium. 3). The geologic record of human times - such as it is - suggests that Man originally inhabited a world of small and few deserts; of salubrious climate; of diversity and even gigantism amongst animal species; and of long life. The geologic record of more recent times contains abundant evidences of desertification, and animal extinction. Some changes, such as the onset of ice-ages and encroachment of the Sahara Desert, were relatively sudden and by definition involved the atmosphere.
The measurements taken as part and parcel of radiocarbon dating therefore corroborate the idea of major atmospheric and climatic change within human history. There was the failure to establish C14 -N14 equilibrium by measurement. There was the uncomfortable discovery that some dates were in error by hundreds of years, necessitating arbitrary adjustment. Then, the assumption that there has been no major atmospheric change led to the blithe certainty that the measurements give an actual age, rather than an exponentially exaggerated unlikelihood pointing not to a date but to atmosphere-altering event(s).
Such objections have been countered: The anomalies in measurement mentioned above, need not carry weight; they are overshadowed by tree-ring and some other measurements which go close to proving a near-steady equilibrium in atmospheric C14 for some tens of thousands of years. (Individual tree rings give every appearance of absorbing the C14 of their year, exclusively. If the rings are counted correctly, and if each one represents a year, there should be reliable calibration. Dead trees believed to have been living nearly 12,000 years ago have been analyzed.) Furthermore, dates obtained by other methods do agree with C14 dates. Thus, experts argue convincingly that this technique is reliably calibrated at least to 10,000BC - the approximate limit of tree-rings. They do have sound reasons for accepting its results far beyond that time.
But has the atmospheric carbon question, of itself, settled into a steady and unperturbable equilibrium, in the same way that the atmospheric C14/N14 exchange is thought to have settled into equilibrium? Are there questions yet to be addressed, after all, in relation to C14? From the viewpoint of a layman, consider this: The published wisdom, relying heavily upon meticulous analyses of dead trees, assumes a more-or-less constant atmospheric C14 mix, back to 12,000 years ago, and well beyond even that date.
Climate and especially climate
change study are in their infancy. Some might suggest that aspects of
climate change research are approximately in the same category as alchemy.
Alchemists needed to tell a good story to get funding, and likewise,
climate change experts. Yet even alchemy produced spinoffs for science.
Let us give climate change research an ounce of credibility for a moment.
(11th May 2007) published the following. Quote: "A University
of Colorado at Boulder-led research team tracing the origin of a large
carbon dioxide increase in Earth's atmosphere at the end of the last
ice age has detected two ancient "burps" that originated from
the deepest parts of the oceans. The new study indicated carbon that
had built up in the oceans over millennia was released in two big pulses,
one about 18,000 years ago and one 13,000 years ago ...... ". To
attempt to understand this startlingly positive assertion, it may be
helpful to factor in the following:
We shall not entangle ourselves in questions of the historicity of the Bible, other than to note that the best of scholars have been divided in their opinions as to the accuracy and intent of its genealogies. Some in the past have been embarrassed through placing too much emphasis on dating by biblical genealogy. Perhaps the most likely candidate for a date-fixing genealogy is the first. It details the lineage from Adam to Noah. If taken at face value, it gives approximately 1,500 years between the advent of Mankind and his near-destruction. Taking genealogies at face value has not been a rewarding exercise. Wherever Man can learn something for himself, divine Wisdom tends to leave him to do so - sometimes in a way that deliberately overthrows any attempt to turn the Bible into a rod of "knowledge" with which to beat people over the head!
Noah's flood remains and will remain shrouded in mystery until technology fully enlightens our understanding. There are four points to ponder, relevant to this ancient tragedy. 1). By comparing the genetic information retained in human DNA with that of other primates it is apparent that humanity once went to the brink of extinction. Our genetic heritage has been severely impoverished. (See Brookes, M., 1999, New Scientist,163 (2199), pp. 33-35.) 2). The world we first inhabited was host to a more diverse and robust fauna and flora than the world subsequent to it. 3). Going backwards from about 4,000BC, human historic records rapidly "drop out". If mankind left any significant record prior to about 4,000BC, something obliterated it. 4). The biblical narrative is strongly suggestive of capture by the earth of a comet into geostationary orbit. The comet probably came in over the north polar region and finally became stationary over the Middle Eastern region. Most comets are believed to contain water ice, but other atmospheric substances such as carbon dioxide, nitrogen, sulfur, etcetera theoretically may be present, along with rocky material. The melting of the comet may have resulted in a deluge of rain, whilst the upwards gravitational pull resulted in a steady tidal surge, high enough to cover mountains. The wind presaging the retreat of the waters could have been a global atmospheric event associated perhaps with either the disintegration or escape of the remnants of this extraterrestrial body. Where it says "I have set my rainbow in the clouds...whenever I bring clouds over the earth and the rainbow appears in the clouds, I will remember my covenant..." it is implying that everyday rain clouds, all of which have the capacity to show a rainbow, are not globally catastrophic. The cloud type associated with Noah's flood did not have rainbow potential. It was a foreign, exceptional atmospheric event. The Tunguska event of 1908 is suggestive of a comet fragment. Periodic interaction between comets and the earth may yet account for previously mysterious events such as the periodic onset of ice ages, the snap-freezing of woolly mammoths and resupply of our atmosphere with essential elements such as carbon.
We are referring to testable and potentially observable facts to which all chemical dating methods must defer. Man, above all other creatures, leaves an indelible fossil record. New York is a reasonable sort of a fossil. The most "primitive" of peoples at least break rocks and leave piles of bones. Where are the layers of cracked rocks and bones to support the proposed dates attributed to ancient Man?
The Australian landmass comprises about 7½ million square km. Take the human population prior to European settlement as ¼ million - a conservative estimate. Assume every member of this population discarded, lost, or broke, one stone axe every 25 years. This again is a conservative estimate. This gives ¼ million stone axes or axe fragments per 25 years: 1 million per century. Assuming these stones weren't collected by aliens, they fell onto the ground at a rate of 1per sq km every 7½ centuries. Round this up to 1 per millennium.
This gives 1 axe per sq km per millennium. The author is no archaeologist, but he has inspected some of the Australian surface. There aren't a lot of stone axes in his backyard. Whether there are enough in all of Australia to overflow the backyard at the Australia Museum, he couldn't say.
One millennium, one axe; two millennia, two axes; three millennia, three axes; forty millennia, forty axes. .. Chemical dates can only be realistically interpreted in the light of hard evidence. The hard evidence, visible, or in this case, invisible - suggests that human habitation of Australia on the balance of probability did not exceed more than one or perhaps two thousand years. Once archaeologists discover this, don't be surprised at how quickly the dating results confirm the new discovery!
It goes without saying that there may be coherent explanations
for the dearth of visible evidence of prolonged human habitation of
the globe. If indeed Man was here for any of those proposed ages, something
kept him very subdued, or something all but scrubbed out his remains.
On one hand there is a documented constancy in C14 content in atmospheric carbon, going back thousands of years. This constancy is relied upon to build a dating method. On the other hand it is being proposed that there were distinguishable carbon input events over the same time period, recognizable as such because the C14 content of the introduced carbon was significantly different. When one thinks of the variables in relation to atmospheric carbon - which is constantly being removed by natural processes and therefore has to somehow be replenished - and then thinks of the variables in relation to cosmic radiation intensity - which can vary not only as a result of events at its source but also as a result of variations in the earth's magnetic field and in the thickness and composition of our atmosphere - surely this earth exceeded itself. Here is constancy that gave us radiocarbon dating concurrent with variability that gave us carbon dioxide -related climate change.
Thawing tundra potentially throws yet another wild card into the human dating game. Soil is rich in microbes, many of which are not killed by being frozen but survive for periods of perhaps tens of thousands of years to once again become active once the ground thaws. Once thawed, they re-enter the food chain and animals higher in the chain imbibe their carbon-14 ratio. Man may mistakenly be thought to be incredibly old - because of snap frozen organic substances stored in the vast freezer space of previously ice- covered continents.
Return to anchor page