Opinion, bristlecone pine carbon dating directly. seems remarkable
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Great Basin Bristlecone pines Pinus longaeva are remarkable for their great age and their ability to survive adverse growing conditions. In fact, it seems one secret to their longevity is the harsh environment in which most bristlecone pines grow. Bristlecone pines in Great Basin National Park grow in isolated groves just below treeline. Conditions are harsh, with cold temperatures, a short growing season, and high winds. Bristlecone pines in these high-elevation environments grow very slowly, and in some years don't even add a ring of growth. This slow growth makes their wood very dense and resistant to insects, fungi, rot, and erosion. Vegetation is very sparse, limiting the role of fire.
There are two basic principles of tree-ring dating. The first can be simply stated: One year; one ring. That is, each year a tree forms one growth ring that can be seen when the trunk is cut. This principle is so well known that even school children deter mine the age of fallen trees by counting the rings of clean-cut stumps. However, botanists have long recognized certain pitfalls in this procedure.
Occasionally climatic conditions are such that no identifiable ring is formed in a given year, or on the other hand, two or more rings may form. The consequences are designated as "missing rings" or "multiple rings," respectively.
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If rings are missing in the count, a falsely low age will appear. The apparent age will be incorrectly long if there are multiple rings. The second basic principle is more elegant and relies on the fact that the width of a ring may depend to a large extent on the amount of rainfall in the year it was formed. Varying rainfall from year to year results in varying widths of rings. In certain locales the consequence is clearly defined ring width patterns reflecting distinct variations in climate.
The principle used for dating is that: If the same distinctive pattern of ring widths is observed in two wood specimens, those two specimens were contemporary and their similar rings may be correlated one by one, year by year. The value and application of this principle is illustrated on page This allows the count of rings to be extended to include the entire older specimen application of first principle.
Similarly, the count can be successively extended back in time as long as successively older wood specimens are found with the requisite matching distinctive ring width patterns. The major limitation to application of this principle is caused by the requirement of a series of specimens, each with distinctive overlapping patterns.!
As a matter of fact, most wood shows little variation in ring width from year to year. Such an indistinctive pattern is termed complacent.
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Complacent specimens are not suitable for use in tree-ring dating because there is no way to be sure which rings in one specimen match with specific rings in another. For a number of years, C.
Ferguson of the University of Arizona has been collecting and studying specimens of bristlecone pine wood from the White Mountains along the California-Nevada border.
A variety of factors combine to make these trees long-lived. The trees are not large but some of them do exhibit thousands of growth rings. By application of both principles of tree-ring dating, Dr. Ferguson has derived a chronology extending to as much as 9, years before the present. Ferguson states, "In bristlecone pines, problems of cross dating are caused by so-called 'missing' rings associated with the extremely slow growth rate of this species on arid sites.
One specimen, for example, contains more than 1, annual rings in In some in stances, 5 per cent or more of the annual rings may be missing along a given radius that spans many centuries.
In fact, nearly half of the samples used for the original 7,year chronology have mean sensitivities of less than. How did Ferguson cross match them? Consider the following:. Cross matching of one pattern with another is largely a matter of visual inspection and judgment. Researchers have usually relied on "skeleton plots," showing only the distinctive features of a distribution as visual aids.
This technique, though quite subjective is very useful; especially when dealing with short patterns.
And one could reason that it is not really important how a crossmatch is found as long as it is verified statistically. However, matching a specimen with hundreds of rings against a chronology with thousands of rings is not easy.
Therefore, in the case of the bristlecone pine chronology, the carbon date of the wood was used to determine the approximate location for crossmatching.
Says Ferguson, "I often am unable to date specimens with one or two thousand rings against a 7,year master chronology, even with the 'ball-park' placement provided by a radiocarbon date. From the foregoing it is evident that a bristlecone pine tree-ring date is at least partially dependent on carbon dating.
Bristlecone pine carbon dating
How dependent it really is can be inferred from the complacent nature of the specimens. Complacent specimens all rings about alike will fit about as well in one place in the chronology as another.
In fact, without a carbon date one would never know where they should fit.
This is a very important point since Ferguson claims that the bristlecone pine chronology "constitutes the first independent time control of such length for radiocarbon analysis. In reality, one wonders how the bristlecone pine chronology can be used to verify the accuracy of carbon dating when the researcher used carbon dating to assist him in developing the tree-ring chronology. This might not be so important if each crossmatch was statistically verified to be in harmony with the second principle of tree-ring dating.
But since the details of such verification have not been published and since the quality of the data is so poor highly complacent ring sequences the crossmatching has not been verified adequately.
Usually the conclusions of scientists are open for investigation. Such investigation rightfully includes the methods and data used in arriving at the conclusion. There should be no "secrets" in the prosecution of truth.
With respect to the bristlecone pine chronology, substantiating investigation has been hampered since the data upon which the conclusions have been based have not yet been made public.
This radiation cannot be totally eliminated from the laboratory, so one could probably get a "radiocarbon" date of fifty thousand years from a pure carbon-free piece of tin. However, you now know why this fact doesn't at all invalidate radiocarbon dates of objects younger than twenty thousand years and is certainly no evidence for the notion that coals and oils might be no older than fifty thousand years.
Question: Creationists such as Cook claim that cosmic radiation is now forming C in the atmosphere about one and one-third times faster than it is decaying. If we extrapolate backwards in time with the proper equations, we find that the earlier the historical period, the less C the atmosphere had. If we extrapolate. If they are right, this means all C ages greater than two or three thousand years need to be lowered drastically and that the earth can be no older than ten thousand years.
Answer: Yes, Cook is right that C is forming today faster than it's decaying.
However, the amount of C has not been rising steadily as Cook maintains; instead, it has fluctuated up and down over the past ten thousand years. How do we know this? From radiocarbon dates taken from bristlecone pines.
There are two ways of dating wood from bristlecone pines: one can count rings or one can radiocarbon-date the wood. Since the tree ring counts have reliably dated some specimens of wood all the way back to BC, one can check out the C dates against the tree-ring-count dates.
Admittedly, this old wood comes from trees that have been dead for hundreds of years, but you don't have to have an 8,year-old bristlecone pine tree alive today to validly determine that sort of date. It is easy to correlate the inner rings of a younger living tree with the outer rings of an older dead tree.
The correlation is possible because, in the Southwest region of the United States, the widths of tree rings vary from year to year with the rainfall, and trees all over the Southwest have the same pattern of variations. When experts compare the tree-ring dates with the C dates, they find that radiocarbon ages before BC are really too young-not too old as Cook maintains. For example, pieces of wood that date at about BC by tree-ring counts date at only BC by regular C dating and BC by Cook's creationist revision of C dating as we see in the article, "Dating, Relative and Absolute," in the Encyclopaedia Britannica.
So, despite creationist claims, C before three thousand years ago was decaying faster than it was being formed and C dating errs on the side of making objects from before BC look too youngnot too old.
Question: But don't trees sometimes produce more than one growth ring per year? Wouldn't that spoil the tree-ring count?
Answer: If anything, the tree-ring sequence suffers far more from missing rings than from double rings. This means that the tree-ring dates would be slightly too young, not too old. Of course, some species of tree tend to produce two or more growth rings per year. But other species produce scarcely any extra rings. Most of the tree-ring sequence is based on the bristlecone pine.
This tree rarely produces even a trace of an extra ring; on the contrary, a typical bristlecone pine has up to 5 percent of its rings missing.
Concerning the sequence of rings derived from the bristlecone pine, Ferguson says:. In certain species of conifers, especially those at lower elevations or in southern latitudes, one season's growth increment may be composed of two or more flushes of growth, each of which may strongly resemble an annual ring.
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In the growth-ring analyses of approximately one thousand trees in the White Mountains, we have, in fact, found no more than three or four occurrences of even incipient multiple growth layers.
In years of severe drought, a bristlecone pine may fail to grow a complete ring all the way around its perimeter; we may find the ring if we bore into the tree from one angle, but not from another.
Hence at least some of the missing rings can be found. Even so, the missing rings are a far more serious problem than any double rings. Other species of trees corroborate the work that Ferguson did with bristlecone pines. Before his work, the tree-ring sequence of the sequoias had been worked out back to BC. The archaeological ring sequence had been worked out back to 59 BC.
The limber pine sequence had been worked out back to 25 BC. The radiocarbon dates and tree-ring dates of these other trees agree with those Ferguson got from the bristlecone pine. But even if he had had no other trees with which to work except the bristlecone pines, that evidence alone would have allowed him to determine the tree-ring chronology back to BC.
See Renfrew for more details. So, creationists who complain about double rings in their attempts to disprove C dating are actually grasping at straws.
If the Flood of Noah occurred around BC, as some creationists claim, then all the bristlecone pines would have to be less than five thousand years old. This would mean that eighty-two hundred years worth of tree rings had to form in five thousand years, which would mean that one-third of all the bristlecone pine rings would have to be extra rings. Creationists are forced into accepting such outlandish conclusions as these in order to jam the facts of nature into the time frame upon which their "scientific" creation model is based.
Question: Creationist Thomas G.
Carbon dating assumes a bristlecone pine is what was introduced in recalibrating dendrochronology and radiocarbon dates. From other species on objects as old as absolute. Willard this longest-living of the bristlecone pine for a tough tree that its wood. In an attempt to bc has been developed, it is what was done independently, Although tree-ring dating is a valid scientific technique, evidence indicates that the most widely known application of this technique is uncertain because of poor quality data and dependency on carbon dating. This latter fact makes it questionable to cite the bristlecone pine chronology in support of carbon dating, or vice versa. Notes. bristlecone pine Rocky Mountain bristlecone pine (Pinus aristata). U.S. Forest Service; The Great Basin bristlecone pine (P. longaeva) has the longest life span of any conifer and is likely the oldest non-clonal tree on Earth. A stand of these pines on Wheeler Peak in eastern Nevada is known to contain several trees over 3, years old and was the site of the Prometheus tree, which was cut.
Barnes has claimed that the earth's magnetic field is decaying exponentially with a half-life of fourteen hundred years. Not only does he consider this proof that the earth can be no older than ten thousand years but he also points out that a greater magnetic strength in the past would reduce C dates.
Now if the magnetic field several thousand years ago was indeed many times stronger than it is today, there would have been less cosmic radiation entering the atmosphere back then and less C would have been produced. Therefore, any C dates taken from objects of that time period would be too high. How do you answer him? Answer: Like Cook, Barnes looks at only part of the evidence. What he ignores is the great body of archaeological and geological data showing that the strength of the magnetic field has been fluctuating up and down for thousands of years and that it has reversed polarity many times in the geological past.
So, when Barnes extrapolates ten thousand years into the past, he concludes that the magnetic field was nineteen times stronger in BC than it is today, when, actually, it was only half as intense then as now.
Nov 19, They have their work cut out for them, however, because radiocarbon (C) dating is one of the most reliable of all the radiometric dating methods. This article will answer several of the most common creationist attacks on carbon dating, using the question-answer format that has proved so useful to lecturers and debaters. Jul 04, In this case, the Bristlecone pine which bears its name was also a sort of a knowledge bringer, as its examination directly affected the development of carbon dating used every day by archeologists and paleontologists, as well as priceless climate data. dating, largely related to improving accuracy of the 14C method via contributions to calibration, stan-dards, and studies to understand processes that might influence results. In many cases, LTRR con-tributions are related to development of the bristlecone pine chronology from the White Mts of Cal-1Corresponding author. Email: [email protected]
This means that radiocarbon ages of objects from that time period will be too young, just as we saw from the bristlecone pine evidence. Question: But how does one know that the magnetic field has fluctuated and reversed polarity? Aren't these just excuses scientists give in order to neutralize Barnes's claims?
Answer: The evidence for fluctuations and reversals of the magnetic field is quite solid. Bucha, a Czech geophysicist, has used archaeological artifacts made of baked clay to determine the strength of the earth's magnetic field when they were manufactured. He found that the earth's magnetic field was 1. See Bailey, Renfrew, and Encyclopedia Britannica for details. In other words, it rose in intensity from 0. Even before the bristlecone pine calibration of C dating was worked out by Ferguson, Bucha predicted that this change in the magnetic field would make radiocarbon dates too young.
This idea [that the fluctuating magnetic field affects influx of cosmic rays, which in turn affects C formation rates] has been taken up by the Czech geophysicist, V. Bucha, who has been able to determine, using samples of baked clay from archeological sites, what the intensity of the earth's magnetic field was at the time in question.
Even before the tree-ring calibration data were available to them, he and the archeologist, Evzen Neustupny, were able to suggest how much this would affect the radiocarbon dates.
Renfrew, p. There is a good correlation between the strength of the earth's magnetic field as determined by Bucha and the deviation of the atmospheric radiocarbon concentration from its normal value as indicated by the tree-ring radiocarbon work. As for the question of polarity reversals, plate tectonics can teach us much.
It is a fact that new oceanic crust continually forms at the mid-oceanic ridges and spreads away from those ridges in opposite directions.
When lava at the ridges hardens, it keeps a trace of the magnetism of the earth's magnetic field. Therefore, every time the magnetic field reverses itself, bands of paleomagnetism of reversed polarity show up on the ocean floor alternated with bands of normal polarity.
These bands are thousands of kilometers long, they vary in width, they lie parallel, and the bands on either side of any given ridge form mirror images of each other. Thus it can be demonstrated that the magnetic field of the earth has reversed itself dozens of times throughout earth history. Barnes, writing inought to have known better than to quote the gropings and guesses of authors of the early sixties in an effort to debunk magnetic reversals.
Before plate tectonics and continental drift became established in the mid-sixties, the known evidence for magnetic reversals was rather scanty, and geophysicists often tried to invent ingenious mechanisms with which to account for this evidence rather than believe in magnetic reversals. However, bysea floor spreading and magnetic reversals had been documented to the satisfaction of almost the entire scientific community.
Yet, instead of seriously attempting to rebut them with up-to-date evidence, Barnes merely quoted the old guesses of authors who wrote before the facts were known. But, in spite of Barnes, paleomagnetism on the sea floor conclusively proves that the magnetic field of the earth oscillates in waves and even reverses itself on occasion.
It has not been decaying exponentially as Barnes maintains. Answer: Yes. When we know the age of a sample through archaeology or historical sources, the C method as corrected by bristlecone pines agrees with the age within the known margin of error.
For instance, Egyptian artifacts can be dated both historically and by radiocarbon, and the results agree. At first, archaeologists used to complain that the C method must be wrong, because it conflicted with well-established archaeological dates; but, as Renfrew has detailed, the archaeological dates were often based on false assumptions.
Radiocarbon Tree-Ring Calibration
One such assumption was that the megalith builders of western Europe learned the idea of megaliths from the Near-Eastern civilizations.
As a result, archaeologists believed that the Western megalith-building cultures had to be younger than the Near Eastern civilizations. Many archaeologists were skeptical when Ferguson's calibration with bristlecone pines was first published, because, according to his method, radiocarbon dates of the Western megaliths showed them to be much older than their Near-Eastern counterparts.
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