Carbon 14 Cultures

Carbon 14 Cultures

Mainstream academia warmly embraced Radiocarbon Dating when the technique was “presented to the world by Willard Libby in 1949”.

Radiocarbon dating (or simply carbon dating) is a radiometric dating technique that uses the decay of carbon-14 (14C) to estimate the age of organic materials, such as wood and leather, up to about 58,000 to 62,000 years Before Present (BP, present defined as CE 1950).

Carbon dating was presented to the world by Willard Libby in 1949, for which he was awarded the Nobel Prize in Chemistry.

The Earth’s atmosphere contains various isotopes of carbon, roughly in constant proportions.

These include the main stable isotope (12C) and an unstable isotope (14C).

Through photosynthesis, plants absorb both forms from carbon dioxide in the atmosphere.

When an organism dies, it contains the standard ratio of 14C to 12C, but as the 14C decays with no possibility of replenishment, the proportion of carbon 14 decreases at a known constant rate.

The time taken for it to reduce by half is known as the half-life of 14C.

The measurement of the remaining proportion of 14C in organic matter thus gives an estimate of its age (a raw radiocarbon age).

However, over time there are small fluctuations in the ratio of 14C to 12C in the atmosphere, fluctuations that have been noted in natural records of the past, such as sequences of tree rings and cave deposits.

These records allow fine-tuning, or “calibration”, of the raw radiocarbon age, to give a more accurate estimate of the calendar date of the material.

One of the most frequent uses of radiocarbon dating is to estimate the age of organic remains from archaeological sites.

Carbon has two stable, nonradioactive isotopes: carbon-12 (12C), and carbon-13 (13C), and a radioactive isotope, carbon-14 (14C), also known as radiocarbon.

The half-life of 14C (the time it takes for half of a given amount of 14C to decay) is about 5,730 years, so its concentration in the atmosphere might be expected to reduce over thousands of years.

However, 14C is constantly being produced in the lower stratosphere and upper troposphere by cosmic rays, which generate neutrons that in turn create 14C when they strike nitrogen-14 (14N) atoms.

http://en.wikipedia.org/wiki/Radiocarbon_dating

However, Radiocarbon Dating is not infallible.

The underlying assumption that the atmospheric isotopes of carbon are always produced “roughly in constant proportions” is a statement of faith [not science].

Similarly, the assumption that at the time of death an organism always “contains the standard ratio of 14C to 12C” is a statement of faith [not science].

Overall, there are numerous confounding factors that are known to influence the results produced by Radiocarbon Dating:

Carbon Exchange Between Reservoirs
The different elements of the carbon exchange reservoir vary in how much carbon they store, and in how long it takes for the 14C generated by cosmic rays to fully mix with them.

Atmospheric Variation
However, in 1958, Hessel de Vries pointed out that this was not the case, by testing wood samples of known ages and showing there was a significant deviation from the expected 14C/12C ratio.

Variations in 14C Production
Two different trends can be seen in the tree ring series. First, there is a long term oscillation with a period of about 9,000 years, which causes radiocarbon dates to be older than true dates for the last 2,000 years, and too young before that.

Variations by Latitude
Since the earth’s magnetic field varies with latitude, the rate of 14C production changes with latitude too, but atmospheric mixing is rapid enough that these variations amount to less than 0.5% of the global concentration.

Variations by Sea Temperature
Because the solubility of CO2 in water increases with lower temperatures, glacial periods would have led to the faster absorption of atmospheric CO2 by the oceans.

Effects of human activity
Coal and oil began to be burned in large quantities during the 1800s.
Dating an object from the early 20th century hence gives an apparent date older than the true date; and for the same reason, 14C concentrations in the neighbourhood of large cities are lower than the atmospheric average.
A much larger effect comes from above-ground nuclear testing, which released large numbers of neutrons and created 14C.

Isotopic Fractionation
The differential uptake of the three carbon isotopes leads to 13C/12C and 14C/12C ratios in plants that differ from the ratios in the atmosphere.
For marine organisms, the details of the photosynthesis reactions are less well understood.
The carbon exchange between atmospheric CO2 and carbonate at the ocean surface is also subject to fractionation.

Reservoir Effects
Libby’s original exchange reservoir hypothesis assumed that the exchange reservoir is constant all over the world, but it has since been discovered that there are several causes of variation in the 14C/12C ratio across the reservoir.

Marine Effect
The CO2 in the atmosphere transfers to the ocean by dissolving in the surface water as carbonate and bicarbonate ions; at the same time the carbonate ions in the water are returning to the air as CO2. This exchange process brings14C from the atmosphere into the surface waters of the ocean, but the 14C thus introduced takes a long time to percolate through the entire volume of the ocean.

Hard Water Effect
If the carbon in freshwater is partly acquired from aged carbon, such as rocks, then the result will be a reduction in the 14C/12C ratio in the water.

Volcanoes
Volcanic eruptions eject large amounts of carbon into the air. The carbon is of geological origin and has no detectable 14C, so the 14C/12C ratio in the vicinity of the volcano is depressed relative to surrounding areas.

Hemisphere Effect
The northern and southern hemispheres have atmospheric circulation systems that are sufficiently independent of each other that there is a noticeable time lag in mixing between the two.

Island Effect
It has been suggested that an “island effect” might exist, by analogy with the mechanism thought to explain the hemisphere effect – since islands are surrounded by water, the carbon exchange between the water and atmosphere might reduce the 14C/12C ratio on an island.

Contamination
Any addition of carbon to a sample of a different age will cause the measured date to be inaccurate. Contamination with modern carbon causes a sample to appear to be younger than it really is: the effect is greater for older samples.

Sample Size
How much sample material is needed to perform testing depends on what is being tested, and also which of the two testing technologies is being used: detectors that record radioactivity, known as beta counters, or atomic mass spectrometers (AMS).

Measurement Errors
For some time, beta counting methods were more accurate than AMS, but there is now little to choose between them, though AMS still cannot compete with the very highest-precision beta counting laboratories, which can provide results with a standard error of ± 20 years.

Conversion Errors
The calculations to convert measured data to an estimate of the age of the sample require the use of several standards. Since different materials have different δ13C values, it is possible for two samples of different materials, of the same age, to have different levels of radioactivity and different 14C/12C ratios. To compensate for this, the measurements are converted to the activity, or isotope ratio, that would have been measured if the sample had been made of wood.

Systematic Errors
It is also possible for laboratories to have systematic errors, caused by weaknesses in their methodologies. For example, if 1% of the benzene in a modern reference sample is allowed to evaporate, the resulting radiocarbon age will be too young by about 80 years.

Limit of Measurability
The limit of measurability is approximately eight half-lives, or about 45,000 years.
Samples older than this will typically be reported as having an infinite age.

Sheep on the beach in North Ronaldsay

See: http://en.wikipedia.org/wiki/Radiocarbon_dating#Dating_considerations

The gradual accumulation of Radiocarbon Discrepancies over the years has enabled the mainstream to develop and evolve a number Calibration Curves [aka consensus hymn sheets] that translate calculated radiocarbon years into calendar years.

The calculations given above produce dates in radiocarbon years: that is, dates which represent the age the sample would be if the 14C/12C ratio had been constant historically.

Although Libby had pointed out as early as 1955 the possibility that this assumption was incorrect, it was not until discrepancies began to accumulate between measured ages and known historical dates for artefacts that it became clear that a correction would need to be applied to radiocarbon ages to obtain calendar dates.

The uncalibrated, raw BP date underestimates the actual age by 3,000 years at 15000 BP.

The underestimation generally runs about 10% to 20%, with 3% of that underestimation attributable to the use of 5,568 years as the half-life of 14C instead of the more accurate 5,730 years.

The calibration curves can vary significantly from a straight line, so comparison of uncalibrated radiocarbon dates (e.g., plotting them on a graph or subtracting dates to give elapsed time) is likely to give misleading results.

There are also significant plateaus in the curves, such as the one from 11,000 to 10,000 radiocarbon years BP, which is believed to be associated with changing ocean circulation during the Younger Dryas period.
Radiocarbon Date Calibration Curve
Calibration curve for the radiocarbon dating scale.
Data sources: Reimer, P. J., et al. (1998).
http://en.wikipedia.org/wiki/Radiocarbon_dating#Calibration

Marine reservoir variations are partly handled by a special marine calibration curve.
http://en.wikipedia.org/wiki/Radiocarbon_dating#Marine_effect

The uncertainty associated with the calibrated calendar years up to 10,000 years ago is claimed to range between 113 and 801 years depending upon whether the sample is from an ill-behaved or well-behaved region.

The calibration method also assumes that the temporal variation in 14C level is global, such that a small number of samples from a specific year are sufficient for calibration.
This was experimentally verified in the 1980s.

Over the historical period (from 0 to 10,000 years BP), the average width of the uncertainty of calibrated dates was found to be 335 years – in well-behaved regions of the calibration curve the width decreased to about 113 years, while in ill-behaved regions it increased to a maximum of 801 years.

Significantly, in the ill-behaved regions of the calibration curve, increasing the precision of the measurements does not have a significant effect on increasing the accuracy of the dates.

http://en.wikipedia.org/wiki/Radiocarbon_dating#Calibration

However, these claimed uncertainty levels are extremely suspect for marine samples where the variable Marine Effect is said to average 440 years.

Marine Effect
This effect is not uniform – the average effect is about 440 years, but there are local deviations of several hundred years for areas that are geographically close to each other.

The effect also applies to marine organisms such as shells, and marine mammals such as whales and seals, which have radiocarbon ages that appear to be hundreds of years old.

http://en.wikipedia.org/wiki/Radiocarbon_dating#Dating_considerations

Gases in Air and Dissolved in Sea Water

Water Encyclopedia
http://www.waterencyclopedia.com/Re-St/Sea-Water-Gases-in.html

Beyond 10,000 years ago the Marine Effect is said to peak at about 900 years.

These marine reservoir effects vary over time as well as geographically; for example, there is evidence that during the Younger Dryas, a period of cold climatic conditions about 12,000 years ago, the apparent difference between the age of surface water and the contemporary atmosphere increased from between 400 and 600 years to about 900 years until the climate warmed again.
http://en.wikipedia.org/wiki/Radiocarbon_dating#Dating_considerations

This uncertainty is further increased when the Calibration Curve translation process returns more than one calendar year value.

Iceman Ötzi - Calibrated Age
The determination of the age of the Iceman from 14C measurements at the AMS laboratories of Zürich and Oxford.

The combined radiocarbon age from these measurements is 4550 ± 19 years BP (Before Present = 1950 AD).

The error is the 68.2% (1s) confidence value.

The uncalibrated age is translated into a calibrated age with the help of the computer program OxCal using the INTCAL98 tree-ring calibration curve.

(a) Calibration curve from 4000 to 2000 BC (Before Christ).
The straight line at 45° indicates a 1:1 transformation of the radiocarbon age into an uncalibrated calendar date.
The intersection of the radiocarbon age with this line and the tree-ring calibration curve shows that the calibrated date is approximately 650 years older.

(b) The enlarged “wiggly” section of the calibration curve leads to three different solutions for the calendar date spanning 250 years.

The small rectangular brackets beneath the peaks indicate the distribution of the 68.2% (1s) confidence ranges into three sections of 3360-3300 BC (29.3%), 3210-3190 BC (19.8%), and 3160-3130 BC (19.1%).

The large brackets indicate the 95.4% (2s) confidence ranges of 3370-3320 BC (34.3%), and 3230-3100 BC (61.1%)

Radiocarbon dating of the Iceman Ötzi with accelerator mass spectrometry
Walter Kutschera – VERA Laboratory, Institute for Isotope Research and Nuclear Physics
University of Vienna
http://www.nupecc.org/iai2001/report/B44.pdf

The confounding factors associated with Radiocarbon Dating are clearly illustrated by the 7,000 year date range associated with five samples from a single rhinoceros bone.

Rhinoceros Bone - Radio Carbon Dating

Archaeological dating using physical phenomena
M J Aitken, Le Garret, Augerolles, Puy-de-Dˆome, 63 930, France
Rep. Prog. Phys. 62 (1999)
http://hbar.phys.msu.su/gorm/dating/dating.pdf

Additionally, the Radiocarbon Dating of multiple specimens from a single site is not guaranteed to resolve the inherent challenges of Radiocarbon Dating because more specimens frequently means there are just more dates that require interpretation.

14C Dating of the Iceman
The AMS laboratories in Zürich and Oxford performed the first 14C measurements on
milligram amounts of bone and tissue from the Iceman.

It is apparent that the calibrated date covers a much larger time range than the uncalibrated radiocarbon age, which is obtained directly from the results of the AMS measurements.

This is due to the “wiggles” in the calibration curve, which results in a 95.4% (2s) confidence range of 3370 to 3100 BC.

Nevertheless, the 14C dating result unambiguously established that the Iceman lived before the Bronze Age (2400 – 800 BC), at the end of the Neolithic period.
Iceman Ötzi
Radiocarbon dating of the Iceman Ötzi with accelerator mass spectrometry
Walter Kutschera – VERA Laboratory, Institute for Isotope Research and Nuclear Physics
University of Vienna
http://www.nupecc.org/iai2001/report/B44.pdf

Unsurprisingly, different academic cultures respond to these challenges in different ways.

The work of Count Eigil Knuth [as presented by Bjarne Grønnow and Jens Fog Jensen] in The Northernmost Ruins of the Globe displays a very cautious approach to Radiocarbon Dating.

Count Eigil Knuth (1903 – 1996) was a Danish explorer, archaeologist, sculptor and writer.

He is referred to as the Nestor (“elder statesman”) of Danish polar explorers.

His most important contribution, however, was the first identification and demonstration of Independence I culture and Independence II culture, immigration waves of Paleo-Eskimo, spread apart by almost 3000 years.

He named the cultures “Independence” after the Independence Fjord located in Peary Land.

http://en.wikipedia.org/wiki/Eigil_Knuth

Count Eigil Knuth

The compilers are aware of the marine effect and also know “how careful one should be when dealing with surface sites”.

Screening the Radiocarbon Dates
Knuth’s series of 71 radiocarbon dates (fig. 11.1) should be sorted and screened prior to any cultural-historical reconstruction.

In order to verify the more reliable measurements we must sort out driftwood dates and dates on marine material, due to the well known difficulties of comparing such dates with dates for local terrestrial material.

Secondly, there are a few obviously erroneous dates which should be left out and, thirdly, the dates should be treated regionally in order to gain a reliable impression of the presence or absence of mankind in specific regions.

Three dates, K-135, K-870 and K-2835 are considered erroneous because they are way out of line with the expected.

All three of them are for musk-ox bone collected from surface deposits, and these dates illustrate how careful one should be when dealing with surface sites in a desert environment where archaeological sites may be palimpsests of many different cultural as well as zoological episodes.

Since the arctic fox is semi-marine, one should actually disregard the date for this reason alone.

When driftwood dates, marine dates and the erroneous dates are disregarded, we are left with 36 dates from Peary Land and the Independence Fjord – Danmark Fjord area, conducted on local wood or bone of musk ox.

These dates (fig. 11.2) clearly indicate the episodic character of the human presence in Peary Land.

The Northernmost Ruins of the Globe
Bjarne Grønnow and Jens Fog Jensen
http://www.oapen.org/download?type=document&docid=342372

The compilers also clearly display the uncertainties associated with Radiocarbon Dating.

Eigil Knuth - Calibrated Dates
The Northernmost Ruins of the Globe
Bjarne Grønnow and Jens Fog Jensen
http://www.oapen.org/download?type=document&docid=342372

On the other hand, when it comes to the Radiocarbon Dating of driftwood, there doesn’t appear to any reference to the marine effect and driftwood with “little decomposition” is deemed “suitable for radiocarbon dating.”

Small diameters and ring widths of driftwood from raised beaches in Arctic Canada are consistent with sources in the northern parts of boreal forests.

Most wood occurs as fragments, less than 20 cm in diameter and less than 1 m long, rather than as logs.

Exceptional pieces are several metres long and as much as 30 cm in diameter.

Growth rings are clear and mostly less than 2 mm, typically about 1 mm wide.

Except for a single occurrence of birch bark (without wood), all samples lacked bark.

Hence, the wood was derived mainly from small-diameter trees that suffered much abrasion and fragmentation in transit, probably by sea ice.

Most of the wood, especially older and larger embedded pieces, is extensively cracked along the grain and delaminated along growth rings.

It generally falls apart on removal from the raised beaches.

Fortunately, however, the wood exhibits little decomposition and is thus suitable for radiocarbon dating.

None of this wood shows any sign of human modification.

Radiocarbon dates - driftwood

Changes in Driftwood Delivery to the Canadian Arctic Archipelago:
The Hypothesis of Postglacial Oscillations of the Transpolar Drift
Arthur S. Dyke, John England, Erk Reimnitz and Helene Jette
Arctic – Volume 50 #1 – March 1997
http://pubs.aina.ucalgary.ca/arctic/Arctic50-1-1.pdf

However, when it comes to the Radiocarbon Dating of marine molluscs “a marine reservoir correction of 550 +/- 100 years” [aka fudge factor] is applied and a special Marine Calibration Curve is used.

Our chronology is derived from 96 radiocarbon dates (including two laboratory duplicates) of marine olluscs (Table 1, Fig. 2).

Of these, we interpret 92 to be either in situ or close to the original site of deposition.

We applied a marine reservoir correction of 550 +/- 100 years, based on dates of historical specimens of known age (Tauber and Funder, 1975) and converted the dates to calendar years using the INTCAL Marine04 dataset (Hughen et al., 2004; Reimer et al., 2004).

There is disagreement about whether the reservoir effect in parts of the North Atlantic region changed during the Younger Dryas (Bard et al., 1994; Halflidason et al., 2000; Waelbroeck et al., 2001; Jennings et al., 2002; Bondevik et al., 2006).

However, we note that reservoir changes during this time are not relevant to our investigation, as the Younger Dryas portion of our chronology comes from extrapolation of a relative sea-level (RSL) curve based almost entirely on Holocene dates.

A single pair of dates of terrestrial plant remains and presumably coeval marine shells from a delta in southern Jameson Land suggests a correction of as much as 700 years during the early Holocene (Funder and Hansen, 1996), which is somewhat greater than that applied here.

However, use of this slightly larger correction would not change the interpretations given below.

Relative Sea-level Changes, Schuchert Dal, East Greenland
B.L. Hall, C. Baroni, G.H. Denton
Quaternary Science Reviews – Volume 29, Issues 25–26, December 2010, Pages 3370–3378
http://www.geology.um.maine.edu/publications/halletal2010qsr.pdf

Sadly, this particular study of Greenland molluscs limited their data analysis to extrapolating “the marine limit” using an exponential curve because the felt it was the best fit.

No curve based on existing data would produce a date for the marine limit much older than ~12,300 cal yr B.P., unless a non-exponential fit was used.

Restricting the fitting exercise solely to exponential curves (typical of regions undergoing isostatic rebound) gave an age range of 11,900-12,300 cal yr B.P. for the marine limit, which we feel represents the best fit to the data.

Relative Sea-level Changes, Schuchert Dal, East Greenland
B.L. Hall, C. Baroni, G.H. Denton
Quaternary Science Reviews – Volume 29, Issues 25–26, December 2010, Pages 3370–3378
http://www.geology.um.maine.edu/publications/halletal2010qsr.pdf

However, the published data can be used to generate graphs for comparison with the [previously referenced] Terrestrial Settlements and Driftwood studies.

Tracking the specimens by species clearly shows there were two major disruptive events that especially disturbed the long running Mya Truncata series.

Schuchert Dal - Scoresby Sound - Species

Two major disruptions [plus three other significant events] are visible in the specimen histogram.

Schuchert Dal - Scoresby Sound - Count

These disruptions are also clearly visible in the Driftwood study.

Comparing the Terrestrial Settlements and Driftwood studies indicates that the periods of human settlement in Northern Greenland occurred during the peaceful gaps after the major disruptive events [which probably obliterated any previous evidence of human settlement].

The same pattern matching can be achieved with the Terrestrial Settlements and Marine Mollusc studies but the timescales of the mollusc study are mismatched by about 4,000 years.

Carbon 14 Cultures

The anomalous Radiocarbon Dates from the Marine Mollusc study are calculated using “a marine reservoir correction of 550 +/- 100 years” [aka fudge factor] and a Marine Calibration Curve based upon the “INTCAL Marine04 dataset”.

The net effect of this Marine Calibration procedure is that a 14C date of 10,000 BP translates to a calendar date of 10,765 which is 635 years younger than the equivalent Terrestrial Calibration.

Marine Calibration Curve

Therefore, the next step in this analysis is to examine the validity of Marine Calibration and the associated fudge factor…

Related Post
Axel Heiberg Island

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Gallery | This entry was posted in Catastrophism, Earth, Greenland, Inventions and Deceptions, Radiocarbon Dating. Bookmark the permalink.

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  1. Pingback: The Red Score: The Baffin Crucible | MalagaBay

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