This essay will consider both the inherent strengths and weaknesses of Radiocarbon dating and Dendrochronology, and also the ways in which these techniques can be applied inappropriately. As might be expected, each of the techniques has limitations and conditions under which it can be applied; it is when the technique is applied to conditions outside these limitations, perhaps for reasons of interpretative determinism, that the integrity of the technique is undermined. Additional to these factors could be a multitude of other considerations not strictly properties of the technique itself. For example, the processes by which the technique is performed and the associated skills and knowledge required to produce accurate determinations will necessarily impact the availability of the technique, but availability and the associated monetary cost is not an intrinsic property of the technique itself. In order to evaluate the technique itself, an idealised situation will be considered, whereby it is assumed that an archaeologist would have equal and otherwise unbiased access to a range of dating techniques, and it remains only to choose the one most appropriate to the situation at hand.
He found a piece that contained rings; another contained rings. Other times, he had to fit together pieces of tree like a jigsaw puzzle. According to Tom Gidwitz:. They've plotted rings from shipwreck timbers and roof beams, and wood from the Mediterranean, Russia, and China.
The bristlecone pine series, the longest built from a single species in a single location, stretches back to It is based on thousands of rings from 81 living trees and dead trees, and Michael found more than three-quarters of the samples. He also recovered one older piece of wood, carbon dated to more than 10, years ago, whose rings cannot yet be linked to the the sequence. Laws and news 2.
Gays in the military. Limitations to the C measurement: There are five main problems with this instrumental technique: If the sample died more than 50, years ago, it would have no measurable C14 left today.
Strengths and weaknesses of radiocarbon dating
Thus, the analysis technique cannot differentiate between samples which are 50 millennia or millennia BP. The ratio of C to Carbon in living matter has not been absolutely constant over the past 50, years: The ratio was higher before the industrial era started to release large amounts of carbon dioxide into the atmosphere. The measured age of any samples which died after the start of industrialization circa CE would appear older than they really are.
This, of course, would not affect the C dating of the shroud of Turin, which is the subject of hot debate between some scientists who believe that the shroud was created in medieval times and some conservative Christians who believe that the shroud was used in Jesus' burial and thus is dated to the 1st century CE.
These techniques utilize the physical parameters of the earth, such as ice cores, annual lake sediments, and astronomical cycles. Ice cores from Greenland and Antarctica show annual layers varves and can be traced up to about 40, years before the layers become too thin due to compaction. Similarly, annual lake sediments can be used to estimate relative age and conventional interpretation for the Green River varves suggests they have been formed over some 20 million years.
Carbon Dating-Strengths and Weaknesses
This implies the earth is at least 20 million years old. Astronomical cycles can also be used to measure relative age. The earth precesses wobbles like a spinning top around the sun in a series of cycles. These cycles affect sunlight and hence long-term can form layers in rock. In some cases these astronomical cycles in rock appear to have been laid down over some 25 million years and radiometric dating puts the absolute age of the rock at some million years.
Here we outline a few dating methods or 'clocks' that present a dating anomaly when referenced to the widely accepted OE age of 4. They appear to be inconsistent with an old earth. At the outset we note C cannot be used to directly date the earth for the simple reason that the unstable C isotope has a half-life of just 5, years. In other words, half of the radioactive isotope in a sample would have decayed to Nitrogen N in just 5, years.
C dating of carbon-bearing materials is therefore limited to roughly 50, years. But YE scientists point out some anomalies in relation to C and a very old earth. For instance, measurable amounts of C have been found in fossil material, such as coal traditionally Carboniferous period c mya. In fact, organic samples from every portion of the Phanerozoic record spanning the last million years on OE dating show detectable amounts of C The implication is that this organic material was either contaminated by new C, or it was buried much more recently and OE dating methods are suspect.
One early approach was based upon ocean salinity [John Joly, 's]. This assumed the ocean was initially pure water and that it's salinity was derived from continental erosion. The technique gave 90 million years, but took no account of the non-constant erosion rate, or the loss and recycling of salt, or the fact that salt is obtained from other sources as well as continents.
More recently, work has been done on ocean sediments [S. Nevins, Institute for Creation Research]. This suggests that, given the current annual rates of erosion some Clearly, this seems incompatible with an ocean billions of years old.
However, this may be a simplistic computation since there is Sediment Recycling as sediments accumulate and cause continental plates to collide, resulting in land uplift and subsequent errosion. The Earth's magnetic field is thought to arise from circulating electic currents in the Earth's molten metalic core, and scientists agree that the field is weakening.
At the current rate of decline it could take just 1, years to disappear, with increasing effects upon the electronic systems of satellites and spacecraft.
Magnetic field decrease applies to other planets. For instance, recent satellite measurements show that Mercury's magnetic field is rapidly decaying and YE Creationists claim this indicates a young field. OE scientists believe that a weakened magnetic field could herald a new magnetic pole reversal. Magnetic pole reversals are rebutted by YE creationists. Instead they claim that the field decrease can be used as a clock to date the earth since it has been decaying since the origin of the earth.
Taking the half-life of the decaying magnetic moment at years , the field is now only about one third as strong as it was at the time of Christ. Working further back in time, the value of the earth's magnetic field approaches that of a magnetic star at 10, years ago. Since this would need a huge nuclear power source, it seems magnetic field decay places an upper age limit on the earth of the order of 10, years.
Whilst the rigour of this YE theory is disputed see talkorigins , recent spacecraft observations have confirmed its planetary magnetic predicions made in !
The decay of uranium and thorium isotopes results in a net build-up of Helium-4 atoms in the atmosphere. It is claimed to be increasing at an annual rate of 3. From these figures and known decay rates, it can be shown that the current amount of atmospheric Helium can be generated in just 11, years not billions of years.
Short-period comets orbit the sun in less than years the Halley comet orbits about every 76 years. Each time they come close to the sun they lose material the comet tail and disintegrate.
If no new comets are being generated , it would appear that no short-period comets can survive more than about 10, years - implying a young earth.Why Carbon Dating Might Be in Danger
This claim is countered by the fact that the origin of short-period comets is still uncertain and that there may be a source of short-period comets e. This is perhaps one of the more challenging anomalies for OE science. It is claimed that Homo sapiens appeared some , to , years ago. But doesn't it seem strange that after more than , years earth's population is still only 7 billion?
After all, the population increased from 1 billion in to 7 billion in - a span of just years! Of course, population growth is exponential, but even then the numbers don't add up. Some claim a world-wide catastrophe may have occurred around 70, years ago, reducing the human population to maybe just 1, breeding pairs. Let's do the maths on these 'catastrophe' figures. Baillie Figure 1. The accuracy of the master chronologies themselves, for it is these that ultimately returns the value for the calendar date, is the determining factor that will return an accurate date or not.
Dendrochronologists use a series of crosslinks between chronologies as shown in Figure 3 above to provide reinforcement of the certainty that the chronology is correct.
Dendrochronology can allow the pinpointing in time of the felling of a single tree and the identification of the use of the wood of that tree across a given site. Dendrochronology can also give an insight into climatic conditions during the lifetime of the tree, as evidenced by dimensions and distinctness of the growth rings.
Dendrochronological dating shares with Radiocarbon dating some of the interpretative issues when the dates are used to provide a chronology or a narrative of a given event. The dates are for the end of the life of the tree, not of the artefact or context that is being interpreted. It has been shown, for example that some of the timbers in the Sweet Track were up to years old when used Baillie This question of residuality must be considered when constructing site chronologies, as the difference between seasoned and green timbers may make a considerable difference if one is looking to determine sub-decade-level chronologies.
Baillie Figure 4. A major strength of both of these techniques is the ability to give a chronological hook on which to hang an interpretation, and the large window of time that the techniques are applicable across see Figure 5.
The effective dating ranges of the different techniques discussed in this book. Walker Fig 1. Whilst Dendrochronology promises, and can deliver, precision and accuracy, the technique is weakened by the limited applicability.
Radiocarbon has a much wider suitability and potential for misuse but the inherent uncertainties of both the process and the determinations mean that accuracy and precision are lacking. However, the sheer number of caveats and adjustments that are required to be applied to the Radiocarbon determinations should be ever-present in the mind whilst using the resulting dates. Essentially, both techniques have their merits, and when used judiciously, and preferably in combinations, useful outcomes may be achieved.
Irish tree rings, Santorini and volcanic dust veils. Nature , , pp.
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